diff mbox series

[v3,4/5] spi: spi-geni-qcom: Add support for GPI dma

Message ID 20210625052213.32260-5-vkoul@kernel.org (mailing list archive)
State New, archived
Headers show
Series Add and enable GPI DMA users | expand

Commit Message

Vinod Koul June 25, 2021, 5:22 a.m. UTC
We can use GPI DMA for devices where it is enabled by firmware. Add
support for this mode

Signed-off-by: Vinod Koul <vkoul@kernel.org>
---
 drivers/spi/spi-geni-qcom.c | 329 ++++++++++++++++++++++++++++++++++--
 1 file changed, 315 insertions(+), 14 deletions(-)

Comments

kernel test robot June 25, 2021, 12:10 p.m. UTC | #1
Hi Vinod,

I love your patch! Perhaps something to improve:

[auto build test WARNING on spi/for-next]
[also build test WARNING on wsa/i2c/for-next asoc/for-next linus/master v5.13-rc7 next-20210624]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Vinod-Koul/Add-and-enable-GPI-DMA-users/20210625-132320
base:   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git for-next
config: x86_64-randconfig-a012-20210625 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 9ca0171a9ffdef5fdb1511d197a3fd72490362de)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # install x86_64 cross compiling tool for clang build
        # apt-get install binutils-x86-64-linux-gnu
        # https://github.com/0day-ci/linux/commit/3632ac4a40c3ef7f86f081d462bf17b45e4c0085
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Vinod-Koul/Add-and-enable-GPI-DMA-users/20210625-132320
        git checkout 3632ac4a40c3ef7f86f081d462bf17b45e4c0085
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

>> drivers/spi/spi-geni-qcom.c:496:44: warning: variable 'i' is uninitialized when used here [-Wuninitialized]
                   dev_err(mas->dev, "Tx[%d] timeout%lu\n", i, timeout);
                                                            ^
   include/linux/dev_printk.h:112:32: note: expanded from macro 'dev_err'
           _dev_err(dev, dev_fmt(fmt), ##__VA_ARGS__)
                                         ^~~~~~~~~~~
   drivers/spi/spi-geni-qcom.c:407:12: note: initialize the variable 'i' to silence this warning
           int ret, i;
                     ^
                      = 0
>> drivers/spi/spi-geni-qcom.c:579:6: warning: variable 'ret' is used uninitialized whenever 'if' condition is true [-Wsometimes-uninitialized]
           if (IS_ERR_OR_NULL(mas->gsi))
               ^~~~~~~~~~~~~~~~~~~~~~~~
   drivers/spi/spi-geni-qcom.c:590:9: note: uninitialized use occurs here
           return ret;
                  ^~~
   drivers/spi/spi-geni-qcom.c:579:2: note: remove the 'if' if its condition is always false
           if (IS_ERR_OR_NULL(mas->gsi))
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   drivers/spi/spi-geni-qcom.c:562:9: note: initialize the variable 'ret' to silence this warning
           int ret;
                  ^
                   = 0
   2 warnings generated.


vim +/i +496 drivers/spi/spi-geni-qcom.c

   398	
   399	static int setup_gsi_xfer(struct spi_transfer *xfer, struct spi_geni_master *mas,
   400				  struct spi_device *spi_slv, struct spi_master *spi)
   401	{
   402		unsigned long flags = DMA_PREP_INTERRUPT | DMA_CTRL_ACK;
   403		struct spi_geni_gsi *gsi;
   404		struct dma_slave_config config = {};
   405		struct gpi_spi_config peripheral = {};
   406		unsigned long timeout, jiffies;
   407		int ret, i;
   408	
   409		config.peripheral_config = &peripheral;
   410		config.peripheral_size = sizeof(peripheral);
   411		peripheral.set_config = true;
   412	
   413		if (xfer->bits_per_word != mas->cur_bits_per_word ||
   414		    xfer->speed_hz != mas->cur_speed_hz) {
   415			mas->cur_bits_per_word = xfer->bits_per_word;
   416			mas->cur_speed_hz = xfer->speed_hz;
   417		}
   418	
   419		if (!(mas->cur_bits_per_word % MIN_WORD_LEN)) {
   420			peripheral.rx_len = ((xfer->len << 3) / mas->cur_bits_per_word);
   421		} else {
   422			int bytes_per_word = (mas->cur_bits_per_word / BITS_PER_BYTE) + 1;
   423	
   424			peripheral.rx_len = (xfer->len / bytes_per_word);
   425		}
   426	
   427		if (xfer->tx_buf && xfer->rx_buf) {
   428			peripheral.cmd = SPI_DUPLEX;
   429		} else if (xfer->tx_buf) {
   430			peripheral.cmd = SPI_TX;
   431			peripheral.rx_len = 0;
   432		} else if (xfer->rx_buf) {
   433			peripheral.cmd = SPI_RX;
   434		}
   435	
   436		if (spi_slv->mode & SPI_LOOP)
   437			peripheral.loopback_en = true;
   438		if (spi_slv->mode & SPI_CPOL)
   439			peripheral.clock_pol_high = true;
   440		if (spi_slv->mode & SPI_CPHA)
   441			peripheral.data_pol_high = true;
   442	
   443		peripheral.cs = spi_slv->chip_select;
   444		peripheral.pack_en = true;
   445		peripheral.word_len = xfer->bits_per_word - MIN_WORD_LEN;
   446		peripheral.fragmentation = FRAGMENTATION;
   447	
   448		ret = get_spi_clk_cfg(mas->cur_speed_hz, mas,
   449				      &peripheral.clk_src, &peripheral.clk_div);
   450		if (ret) {
   451			dev_err(mas->dev, "Err in get_spi_clk_cfg() :%d\n", ret);
   452			return ret;
   453		}
   454	
   455		gsi = &mas->gsi[mas->num_xfers];
   456		gsi->rx_cb.mas = mas;
   457		gsi->rx_cb.xfer = xfer;
   458	
   459		if (peripheral.cmd & SPI_RX) {
   460			dmaengine_slave_config(mas->rx, &config);
   461			gsi->rx_desc = dmaengine_prep_slave_sg(mas->rx, xfer->rx_sg.sgl, xfer->rx_sg.nents,
   462							       DMA_DEV_TO_MEM, flags);
   463			if (!gsi->rx_desc) {
   464				dev_err(mas->dev, "Err setting up rx desc\n");
   465				return -EIO;
   466			}
   467			gsi->rx_desc->callback_result = spi_gsi_rx_callback_result;
   468			gsi->rx_desc->callback_param = &gsi->rx_cb;
   469		}
   470	
   471		dmaengine_slave_config(mas->tx, &config);
   472		gsi->tx_desc = dmaengine_prep_slave_sg(mas->tx, xfer->tx_sg.sgl, xfer->tx_sg.nents,
   473						       DMA_MEM_TO_DEV, flags);
   474		if (!gsi->tx_desc) {
   475			dev_err(mas->dev, "Err setting up tx desc\n");
   476			return -EIO;
   477		}
   478	
   479		gsi->tx_cb.mas = mas;
   480		gsi->tx_cb.xfer = xfer;
   481		gsi->tx_desc->callback_result = spi_gsi_tx_callback_result;
   482		gsi->tx_desc->callback_param = &gsi->tx_cb;
   483	
   484		if (peripheral.cmd & SPI_RX)
   485			gsi->rx_cookie = dmaengine_submit(gsi->rx_desc);
   486		gsi->tx_cookie = dmaengine_submit(gsi->tx_desc);
   487	
   488		if (peripheral.cmd & SPI_RX)
   489			dma_async_issue_pending(mas->rx);
   490		dma_async_issue_pending(mas->tx);
   491		mas->num_xfers++;
   492	
   493		jiffies = msecs_to_jiffies(SPI_XFER_TIMEOUT_MS);
   494		timeout = wait_for_completion_timeout(&mas->tx_cb, jiffies);
   495		if (timeout <= 0) {
 > 496			dev_err(mas->dev, "Tx[%d] timeout%lu\n", i, timeout);
   497			ret = -ETIMEDOUT;
   498			goto err_gsi_geni_transfer_one;
   499		}
   500	
   501		if (peripheral.cmd & SPI_RX) {
   502			jiffies = msecs_to_jiffies(SPI_XFER_TIMEOUT_MS);
   503			timeout = wait_for_completion_timeout(&mas->rx_cb, jiffies);
   504			if (timeout <= 0) {
   505				dev_err(mas->dev, "Rx[%d] timeout%lu\n", i, timeout);
   506				ret = -ETIMEDOUT;
   507				goto err_gsi_geni_transfer_one;
   508			}
   509		}
   510	
   511		spi_finalize_current_transfer(spi);
   512		return 0;
   513	
   514	err_gsi_geni_transfer_one:
   515		dmaengine_terminate_all(mas->tx);
   516		return ret;
   517	}
   518	
   519	static bool geni_can_dma(struct spi_controller *ctlr,
   520				 struct spi_device *slv, struct spi_transfer *xfer)
   521	{
   522		struct spi_geni_master *mas = spi_master_get_devdata(slv->master);
   523	
   524		/* check if dma is supported */
   525		if (mas->cur_xfer_mode == GENI_GPI_DMA)
   526			return true;
   527	
   528		return false;
   529	}
   530	
   531	static int spi_geni_prepare_message(struct spi_master *spi,
   532						struct spi_message *spi_msg)
   533	{
   534		struct spi_geni_master *mas = spi_master_get_devdata(spi);
   535		int ret;
   536	
   537		switch (mas->cur_xfer_mode) {
   538		case GENI_SE_FIFO:
   539			if (spi_geni_is_abort_still_pending(mas))
   540				return -EBUSY;
   541			ret = setup_fifo_params(spi_msg->spi, spi);
   542			if (ret)
   543				dev_err(mas->dev, "Couldn't select mode %d\n", ret);
   544			return ret;
   545	
   546		case GENI_GPI_DMA:
   547			mas->num_xfers = 0;
   548			reinit_completion(&mas->tx_cb);
   549			reinit_completion(&mas->rx_cb);
   550			memset(mas->gsi, 0, (sizeof(struct spi_geni_gsi) * NUM_SPI_XFER));
   551	
   552			return 0;
   553		}
   554	
   555		dev_err(mas->dev, "Mode not supported %d", mas->cur_xfer_mode);
   556		return -EINVAL;
   557	}
   558	
   559	static int spi_geni_grab_gpi_chan(struct spi_geni_master *mas)
   560	{
   561		size_t gsi_sz;
   562		int ret;
   563	
   564		mas->tx = dma_request_chan(mas->dev, "tx");
   565		if (IS_ERR_OR_NULL(mas->tx)) {
   566			dev_err(mas->dev, "Failed to get tx DMA ch %ld", PTR_ERR(mas->tx));
   567			ret = PTR_ERR(mas->tx);
   568			goto err_tx;
   569		}
   570		mas->rx = dma_request_chan(mas->dev, "rx");
   571		if (IS_ERR_OR_NULL(mas->rx)) {
   572			dev_err(mas->dev, "Failed to get rx DMA ch %ld", PTR_ERR(mas->rx));
   573			ret = PTR_ERR(mas->rx);
   574			goto err_rx;
   575		}
   576	
   577		gsi_sz = sizeof(struct spi_geni_gsi) * NUM_SPI_XFER;
   578		mas->gsi = devm_kzalloc(mas->dev, gsi_sz, GFP_KERNEL);
 > 579		if (IS_ERR_OR_NULL(mas->gsi))
   580			goto err_mem;
   581		return 0;
   582	
   583	err_mem:
   584		dma_release_channel(mas->rx);
   585	err_rx:
   586		dma_release_channel(mas->tx);
   587	err_tx:
   588		mas->tx = NULL;
   589		mas->rx = NULL;
   590		return ret;
   591	}
   592	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
Doug Anderson June 28, 2021, 11:37 p.m. UTC | #2
Hi,

On Thu, Jun 24, 2021 at 10:22 PM Vinod Koul <vkoul@kernel.org> wrote:
>
> We can use GPI DMA for devices where it is enabled by firmware. Add
> support for this mode
>
> Signed-off-by: Vinod Koul <vkoul@kernel.org>
> ---
>  drivers/spi/spi-geni-qcom.c | 329 ++++++++++++++++++++++++++++++++++--
>  1 file changed, 315 insertions(+), 14 deletions(-)

Not a truly full review since I haven't looked into the whole GSI DMA
driver, but I tried to go over most of your changes.


> +#define GSI_LOOPBACK_EN                (BIT(0))
> +#define GSI_CS_TOGGLE          (BIT(3))
> +#define GSI_CPHA               (BIT(4))
> +#define GSI_CPOL               (BIT(5))
> +
> +#define MAX_TX_SG              (3)
> +#define NUM_SPI_XFER           (8)
> +#define SPI_XFER_TIMEOUT_MS    (250)

nit: don't need the extra parenthesis around everything above and it
doesn't match the existing definitions too.


> +struct gsi_desc_cb {
> +       struct spi_geni_master *mas;
> +       struct spi_transfer *xfer;
> +};
> +
> +struct spi_geni_gsi {
> +       dma_cookie_t tx_cookie;
> +       dma_cookie_t rx_cookie;
> +       struct dma_async_tx_descriptor *tx_desc;
> +       struct dma_async_tx_descriptor *rx_desc;
> +       struct gsi_desc_cb tx_cb;
> +       struct gsi_desc_cb rx_cb;
> +};

I'd be curious if others feel the same way, but to me it kinda feels
like this should be:

struct spi_geni_gsi_pipe {
  dma_cookie_t cookie;
  struct dma_async_tx_descriptor *desc;
  struct gsi_desc_cb cb;
};

struct spi_geni_gsi {
  spi_geni_gsi_pipe tx;
  spi_geni_gsi_pipe rx;
};

That would actually make spi_gsi_callback_result() more elegant
because you could pass in the correct structure and then a string "RX"
or "TX" and get rid of the bool.


> @@ -84,6 +110,13 @@ struct spi_geni_master {
>         int irq;
>         bool cs_flag;
>         bool abort_failed;
> +       struct spi_geni_gsi *gsi;

Maybe do something to make it obvious that this points to an array of
NUM_SPI_XFER transfers.

If my math is right then "gsi" is expected to be about 256 bytes big.
I guess you made this a pointer and only allocated it in GSI mode to
save those 256 bytes in non-GSI mode?


> +static void
> +spi_gsi_callback_result(void *cb, const struct dmaengine_result *result, bool tx)
> +{
> +       struct gsi_desc_cb *gsi = cb;
> +
> +       if (result->result != DMA_TRANS_NOERROR) {id'd do
> +               dev_err(gsi->mas->dev, "%s DMA txn failed\n", tx ? "TX" : "RX");
> +               return;
> +       }
> +
> +       if (!result->residue) {
> +               if (tx)
> +                       complete(&gsi->mas->tx_cb);
> +               else
> +                       complete(&gsi->mas->rx_cb);
> +       } else {
> +               dev_err(gsi->mas->dev, "%s DMA txn has pending %d data\n",
> +                       tx ? "TX" : "RX", result->residue);

I guess you just wait for the timeout in this case since you don't complete?


> +static int setup_gsi_xfer(struct spi_transfer *xfer, struct spi_geni_master *mas,
> +                         struct spi_device *spi_slv, struct spi_master *spi)
> +{
> +       unsigned long flags = DMA_PREP_INTERRUPT | DMA_CTRL_ACK;
> +       struct spi_geni_gsi *gsi;
> +       struct dma_slave_config config = {};
> +       struct gpi_spi_config peripheral = {};
> +       unsigned long timeout, jiffies;

Is it really a good idea to have a local variable called "jiffies"?
Isn't the global called "jiffies"?


> +       int ret, i;
> +
> +       config.peripheral_config = &peripheral;
> +       config.peripheral_size = sizeof(peripheral);
> +       peripheral.set_config = true;
> +
> +       if (xfer->bits_per_word != mas->cur_bits_per_word ||
> +           xfer->speed_hz != mas->cur_speed_hz) {
> +               mas->cur_bits_per_word = xfer->bits_per_word;
> +               mas->cur_speed_hz = xfer->speed_hz;
> +       }

It seems a bit pointless to copy these things into "mas" for GSI mode
and even more pointless to have the "if" test first.

In FIFO mode I believe we stored them in "mas" because we needed them
from the interrupt handler. It also lets us optimize and avoid calls
if the config didn't change. You don't need them for either of these
reasons, do you?

Actually, you might possibly want to keep "cur_speed_hz" and use it to
avoid a call to get_spi_clk_cfg() which, at least at one point in
time, was a bit slow.


> +       if (!(mas->cur_bits_per_word % MIN_WORD_LEN)) {
> +               peripheral.rx_len = ((xfer->len << 3) / mas->cur_bits_per_word);
> +       } else {
> +               int bytes_per_word = (mas->cur_bits_per_word / BITS_PER_BYTE) + 1;
> +
> +               peripheral.rx_len = (xfer->len / bytes_per_word);
> +       }

I guess you could only do the above if "rx_buf" and then you don't
have to zero it back out below.


> +       if (xfer->tx_buf && xfer->rx_buf) {
> +               peripheral.cmd = SPI_DUPLEX;
> +       } else if (xfer->tx_buf) {
> +               peripheral.cmd = SPI_TX;
> +               peripheral.rx_len = 0;
> +       } else if (xfer->rx_buf) {
> +               peripheral.cmd = SPI_RX;
> +       }
> +
> +       if (spi_slv->mode & SPI_LOOP)
> +               peripheral.loopback_en = true;
> +       if (spi_slv->mode & SPI_CPOL)
> +               peripheral.clock_pol_high = true;
> +       if (spi_slv->mode & SPI_CPHA)
> +               peripheral.data_pol_high = true;

nit: I'd do it without the "if"s.

peripheral.loopback_en = spi_slv->mode & SPI_LOOP;

In theory much of this could also be done at function init time but I
dunno if it makes a huge difference, like:

struct gpi_spi_config peripheral = {
  .loopback_en = spi_slv->mode & SPI_LOOP,
  .clock_pol_high = spi_slv->mode & SPI_CPOL,
  ...
};


> +       peripheral.cs = spi_slv->chip_select;
> +       peripheral.pack_en = true;
> +       peripheral.word_len = xfer->bits_per_word - MIN_WORD_LEN;
> +       peripheral.fragmentation = FRAGMENTATION;
> +
> +       ret = get_spi_clk_cfg(mas->cur_speed_hz, mas,
> +                             &peripheral.clk_src, &peripheral.clk_div);
> +       if (ret) {
> +               dev_err(mas->dev, "Err in get_spi_clk_cfg() :%d\n", ret);
> +               return ret;
> +       }
> +
> +       gsi = &mas->gsi[mas->num_xfers];

It sure feels like you should error-check this against NUM_SPI_XFER.
Otherwise if someone does a transfer with more than 8 parts you're
totally hosed, right?

Actually, why do you even need an array here? It seems like by the
time this function exits the transfer will be all done, right? So you
can just keep using the same structure over and over again? It can
even be on the stack?


> +       gsi->rx_cb.mas = mas;
> +       gsi->rx_cb.xfer = xfer;
> +
> +       if (peripheral.cmd & SPI_RX) {
> +               dmaengine_slave_config(mas->rx, &config);
> +               gsi->rx_desc = dmaengine_prep_slave_sg(mas->rx, xfer->rx_sg.sgl, xfer->rx_sg.nents,
> +                                                      DMA_DEV_TO_MEM, flags);
> +               if (!gsi->rx_desc) {
> +                       dev_err(mas->dev, "Err setting up rx desc\n");
> +                       return -EIO;
> +               }
> +               gsi->rx_desc->callback_result = spi_gsi_rx_callback_result;
> +               gsi->rx_desc->callback_param = &gsi->rx_cb;
> +       }
> +
> +       dmaengine_slave_config(mas->tx, &config);
> +       gsi->tx_desc = dmaengine_prep_slave_sg(mas->tx, xfer->tx_sg.sgl, xfer->tx_sg.nents,
> +                                              DMA_MEM_TO_DEV, flags);
> +       if (!gsi->tx_desc) {
> +               dev_err(mas->dev, "Err setting up tx desc\n");
> +               return -EIO;
> +       }

I haven't dug deeply, but it surprises me that we do all the TX config
even if "xfer->tx_buf" is NULL.


> +       gsi->tx_cb.mas = mas;
> +       gsi->tx_cb.xfer = xfer;
> +       gsi->tx_desc->callback_result = spi_gsi_tx_callback_result;
> +       gsi->tx_desc->callback_param = &gsi->tx_cb;
> +
> +       if (peripheral.cmd & SPI_RX)
> +               gsi->rx_cookie = dmaengine_submit(gsi->rx_desc);
> +       gsi->tx_cookie = dmaengine_submit(gsi->tx_desc);
> +
> +       if (peripheral.cmd & SPI_RX)
> +               dma_async_issue_pending(mas->rx);
> +       dma_async_issue_pending(mas->tx);
> +       mas->num_xfers++;
> +
> +       jiffies = msecs_to_jiffies(SPI_XFER_TIMEOUT_MS);
> +       timeout = wait_for_completion_timeout(&mas->tx_cb, jiffies);

You're waiting a hardcoded 250 ms for every transfer. That could be
too short for a long transfer. Can you use some logic like the SPI
framework?

It's probably also worth adding a comment about why you can't just
return "1" from transfer_one() for GSI mode and let the SPI framework
handle the timeout calculations. My guess is that you might need extra
time because another processor might hold the SPI bus and keep you
from starting your transfer right away and thus your timeout needs to
be somehow longer than the normal SPI framework. Is that true?

Actually, it looks like spi_transfer_wait() already has 200 ms of
slop. Is that enough for you? Can you just let the SPI framework
handle the timeout?


> +       if (timeout <= 0) {

Just "== 0". "timeout" is unsigned, right?


> +               dev_err(mas->dev, "Tx[%d] timeout%lu\n", i, timeout);

timeout is always 0 in this printout.


> +               ret = -ETIMEDOUT;
> +               goto err_gsi_geni_transfer_one;
> +       }
> +
> +       if (peripheral.cmd & SPI_RX) {
> +               jiffies = msecs_to_jiffies(SPI_XFER_TIMEOUT_MS);
> +               timeout = wait_for_completion_timeout(&mas->rx_cb, jiffies);

Why do you need to re-init the timeout? You should just wait for
however much is left from the previous wait? The TX and RX should be
happening in parallel, right? So you don't want to wait for a full
second transfer.


> +               if (timeout <= 0) {
> +                       dev_err(mas->dev, "Rx[%d] timeout%lu\n", i, timeout);
> +                       ret = -ETIMEDOUT;
> +                       goto err_gsi_geni_transfer_one;
> +               }
> +       }
> +
> +       spi_finalize_current_transfer(spi);
> +       return 0;
> +
> +err_gsi_geni_transfer_one:
> +       dmaengine_terminate_all(mas->tx);

I know not what I'm talking about, but the description of
dmaengine_terminate_all says "This function is DEPRECATED". It also
seems like the old "terminate_all" is async? That's bad because you
gave it stack pointers...

You almost certainly want a WARN_ON or something like that if you fail
to terminate the transfer because, presumably, the DMA engine will
keep looking at your config that's stored on the stack (that you're
freeing by ending the function). That's super bad and I'd want a
pretty serious warning in my logs if it might be happening.


> +static bool geni_can_dma(struct spi_controller *ctlr,
> +                        struct spi_device *slv, struct spi_transfer *xfer)
> +{
> +       struct spi_geni_master *mas = spi_master_get_devdata(slv->master);
> +
> +       /* check if dma is supported */
> +       if (mas->cur_xfer_mode == GENI_GPI_DMA)
> +               return true;
> +
> +       return false;
> +}

nit: might as well handle GENI_SE_DMA as well since it's just as easy
to test against GENI_SE_FIFO?

nit: no need for an if.

So just: return mas->cur_xfer_mode != GENI_SE_FIFO;


>  static int spi_geni_prepare_message(struct spi_master *spi,
>                                         struct spi_message *spi_msg)
>  {
> -       int ret;
>         struct spi_geni_master *mas = spi_master_get_devdata(spi);
> +       int ret;
>
> -       if (spi_geni_is_abort_still_pending(mas))
> -               return -EBUSY;
> +       switch (mas->cur_xfer_mode) {
> +       case GENI_SE_FIFO:
> +               if (spi_geni_is_abort_still_pending(mas))
> +                       return -EBUSY;
> +               ret = setup_fifo_params(spi_msg->spi, spi);
> +               if (ret)
> +                       dev_err(mas->dev, "Couldn't select mode %d\n", ret);
> +               return ret;
>
> -       ret = setup_fifo_params(spi_msg->spi, spi);
> -       if (ret)
> -               dev_err(mas->dev, "Couldn't select mode %d\n", ret);
> +       case GENI_GPI_DMA:
> +               mas->num_xfers = 0;
> +               reinit_completion(&mas->tx_cb);
> +               reinit_completion(&mas->rx_cb);
> +               memset(mas->gsi, 0, (sizeof(struct spi_geni_gsi) * NUM_SPI_XFER));

nit: make a #define for the size and use it here and in allocation?


> +static int spi_geni_grab_gpi_chan(struct spi_geni_master *mas)
> +{
> +       size_t gsi_sz;
> +       int ret;
> +
> +       mas->tx = dma_request_chan(mas->dev, "tx");
> +       if (IS_ERR_OR_NULL(mas->tx)) {

I don't think dma_request_chan() can return NULL.


> +               dev_err(mas->dev, "Failed to get tx DMA ch %ld", PTR_ERR(mas->tx));
> +               ret = PTR_ERR(mas->tx);

niftier: ret = dev_err_probe(mas->dev, PTR_ERR(mas->tx), "Failed to
get tx DMA ch\n");

If you don't think that's nifty, at least you should add a "\n" to
your error message.


> +               goto err_tx;
> +       }

Personally I'm a fan of devm_add_action_or_reset() to simplify error
handling like this. Everything becomes easier to handle then.

ret = devm_add_action_or_reset(mas->dev, spi_geni_dma_release_chan, mas->tx);
if (ret)
  return ret;

You've got to make a tiny spi_geni_dma_release_chan() function that
just wraps dma_release_chan() (or cast and violate the C standard) but
then you get rid of all error handling in this function, get rid of
the code you had to add to remove and the code you forgot to add the
the probe() function (see below). :-)


> +       mas->rx = dma_request_chan(mas->dev, "rx");
> +       if (IS_ERR_OR_NULL(mas->rx)) {
> +               dev_err(mas->dev, "Failed to get rx DMA ch %ld", PTR_ERR(mas->rx));
> +               ret = PTR_ERR(mas->rx);
> +               goto err_rx;
> +       }
> +
> +       gsi_sz = sizeof(struct spi_geni_gsi) * NUM_SPI_XFER;
> +       mas->gsi = devm_kzalloc(mas->dev, gsi_sz, GFP_KERNEL);
> +       if (IS_ERR_OR_NULL(mas->gsi))
> +               goto err_mem;

This is not correct. kzalloc() never returns errors, just NULL. ...and
you don't set "ret".

Also: since you re-use this over and over and zero it before each
transfer, you could probably avoid the zero-allocation.


> @@ -349,15 +594,15 @@ static int spi_geni_init(struct spi_geni_master *mas)
>  {
>         struct geni_se *se = &mas->se;
>         unsigned int proto, major, minor, ver;
> -       u32 spi_tx_cfg;
> +       u32 spi_tx_cfg, fifo_disable;
> +       int ret = -ENXIO;
>
>         pm_runtime_get_sync(mas->dev);
>
>         proto = geni_se_read_proto(se);
>         if (proto != GENI_SE_SPI) {
>                 dev_err(mas->dev, "Invalid proto %d\n", proto);
> -               pm_runtime_put(mas->dev);
> -               return -ENXIO;
> +               goto out_pm;

nit: In theory this change could be relegated to a tiny cleanup patch
just to make your GPI change smaller to review, but I won't insist.


> @@ -380,15 +625,38 @@ static int spi_geni_init(struct spi_geni_master *mas)
>         else
>                 mas->oversampling = 1;
>
> -       geni_se_select_mode(se, GENI_SE_FIFO);
> +       fifo_disable = readl(se->base + GENI_IF_DISABLE_RO) & FIFO_IF_DISABLE;
> +       switch (fifo_disable) {
> +       case 1:
> +               ret = spi_geni_grab_gpi_chan(mas);
> +               if (!ret) { /* success case */
> +                       mas->cur_xfer_mode = GENI_GPI_DMA;
> +                       geni_se_select_mode(se, GENI_GPI_DMA);
> +                       dev_dbg(mas->dev, "Using GPI DMA mode for SPI\n");
> +                       break;
> +               }
> +               /*
> +                * in case of failure to get dma channel, we can till do the
> +                * FIFO mode, so fallthrough

s/till/still/

> +                */
> +               dev_warn(mas->dev, "FIFO mode disabled, but couldn't get DMA, fall back to FIFO mode\n");
> +               fallthrough;

I was under the impression that if `FIFO_IF_DISABLE` was set that the
FIFO was, how shall we say it, "disabled". ;-) If you can in fact fall
back to FIFO mode then that bit seems pretty poorly named.


>  static irqreturn_t geni_spi_isr(int irq, void *data)
> @@ -671,6 +942,15 @@ static int spi_geni_probe(struct platform_device *pdev)
>         if (irq < 0)
>                 return irq;
>
> +       ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));

nit: this function already has the line:

struct device *dev = &pdev->dev;

...so you can use "dev". :-)


> +       if (ret) {
> +               ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
> +               if (ret) {
> +                       dev_err(&pdev->dev, "could not set DMA mask\n");
> +                       return ret;

niftier: return dev_err_probe(dev, ret, "could not set DMA mask\n");


> @@ -710,14 +990,17 @@ static int spi_geni_probe(struct platform_device *pdev)
>         spi->max_speed_hz = 50000000;
>         spi->prepare_message = spi_geni_prepare_message;
>         spi->transfer_one = spi_geni_transfer_one;
> +       spi->can_dma = geni_can_dma;
> +       spi->dma_map_dev = mas->dev->parent;

mas->dev->parent == dev->parent ?


> @@ -738,6 +1021,14 @@ static int spi_geni_probe(struct platform_device *pdev)
>         if (ret)
>                 goto spi_geni_probe_runtime_disable;
>
> +       /*
> +        * check the mode supported and set_cs for fifo mode only
> +        * for dma (gsi) mode, the gsi will set cs based on params passed in
> +        * TRE
> +        */
> +       if (mas->cur_xfer_mode == GENI_SE_FIFO)
> +               spi->set_cs = spi_geni_set_cs;

I'm curious: is there no way to get set_cs() working in GPI mode? In
an off-thread conversation Qualcomm seemed to indicate that it was
possible, but maybe they didn't quite understand what I was asking.

Without an implementation of set_cs() there will be drivers in Linux
that simply aren't compatible because they make the assumption that
they can lock the bus, set the CS, and do several transfers that are
part of some logical "transaction". I believe that both of the SPI
peripherals on boards that I work on, cros-ec and the SPI TPM make
this assumption. I don't even believe that the drivers can be "fixed"
because the requirement is more at the protocol level. The protocol
requires you to do things like:

0. Lock the bus.
1. Set the CS.
2. Transfer a few bytes, reading the response as you go.
3. Once you see the other side respond that it's ready, transfer some
more bytes.
4. Release the CS.
5. Unlock the bus.

You can't do this without a set_cs() implementation because of the
requirement to read the responses of the other side before moving on
to the next phase of the transfer.

As I understand it this is roughly the equivalent of i2c clock
stretching but much more ad-hoc and defined peripherals-by-peripheral.

In any case, I guess you must have examples of peripherals that need
GPI mode and don't need set_cs() so we shouldn't block your way
forward, but I'm just curious if you had more info on this.


>  static int spi_geni_remove(struct platform_device *pdev)
>  {
>         struct spi_master *spi = platform_get_drvdata(pdev);
> @@ -762,6 +1061,8 @@ static int spi_geni_remove(struct platform_device *pdev)
>         /* Unregister _before_ disabling pm_runtime() so we stop transfers */
>         spi_unregister_master(spi);
>
> +       spi_geni_release_dma_chan(mas);
> +

Why isn't there a call to spi_geni_release_dma_chan() in the error
paths for probe?


-Doug
Vinod Koul Oct. 14, 2021, 4:04 p.m. UTC | #3
Hi Doug,

On 28-06-21, 16:37, Doug Anderson wrote:
> Hi,
> 
> On Thu, Jun 24, 2021 at 10:22 PM Vinod Koul <vkoul@kernel.org> wrote:
> >
> > We can use GPI DMA for devices where it is enabled by firmware. Add
> > support for this mode
> >
> > Signed-off-by: Vinod Koul <vkoul@kernel.org>
> > ---
> >  drivers/spi/spi-geni-qcom.c | 329 ++++++++++++++++++++++++++++++++++--
> >  1 file changed, 315 insertions(+), 14 deletions(-)
> 
> Not a truly full review since I haven't looked into the whole GSI DMA
> driver, but I tried to go over most of your changes.
> 
> 
> > +#define GSI_LOOPBACK_EN                (BIT(0))
> > +#define GSI_CS_TOGGLE          (BIT(3))
> > +#define GSI_CPHA               (BIT(4))
> > +#define GSI_CPOL               (BIT(5))
> > +
> > +#define MAX_TX_SG              (3)
> > +#define NUM_SPI_XFER           (8)
> > +#define SPI_XFER_TIMEOUT_MS    (250)
> 
> nit: don't need the extra parenthesis around everything above and it
> doesn't match the existing definitions too.

yes, fixed it

> > +struct gsi_desc_cb {
> > +       struct spi_geni_master *mas;
> > +       struct spi_transfer *xfer;
> > +};
> > +
> > +struct spi_geni_gsi {
> > +       dma_cookie_t tx_cookie;
> > +       dma_cookie_t rx_cookie;
> > +       struct dma_async_tx_descriptor *tx_desc;
> > +       struct dma_async_tx_descriptor *rx_desc;
> > +       struct gsi_desc_cb tx_cb;
> > +       struct gsi_desc_cb rx_cb;
> > +};
> 
> I'd be curious if others feel the same way, but to me it kinda feels
> like this should be:
> 
> struct spi_geni_gsi_pipe {
>   dma_cookie_t cookie;
>   struct dma_async_tx_descriptor *desc;
>   struct gsi_desc_cb cb;
> };
> 
> struct spi_geni_gsi {
>   spi_geni_gsi_pipe tx;
>   spi_geni_gsi_pipe rx;
> };
> 
> That would actually make spi_gsi_callback_result() more elegant
> because you could pass in the correct structure and then a string "RX"
> or "TX" and get rid of the bool.

So this and the below comment about using spi fwk to do that wait, made
me ponder upon this bit. So I went ahead with scissors and managed to
chop this off as well as the waiting routines below. This makes code
simpler to read as well.

So we dont need these structs here and wait code anymore.

> > @@ -84,6 +110,13 @@ struct spi_geni_master {
> >         int irq;
> >         bool cs_flag;
> >         bool abort_failed;
> > +       struct spi_geni_gsi *gsi;
> 
> Maybe do something to make it obvious that this points to an array of
> NUM_SPI_XFER transfers.

> If my math is right then "gsi" is expected to be about 256 bytes big.
> I guess you made this a pointer and only allocated it in GSI mode to
> save those 256 bytes in non-GSI mode?
> > +static void
> > +spi_gsi_callback_result(void *cb, const struct dmaengine_result *result, bool tx)
> > +{
> > +       struct gsi_desc_cb *gsi = cb;
> > +
> > +       if (result->result != DMA_TRANS_NOERROR) {id'd do
> > +               dev_err(gsi->mas->dev, "%s DMA txn failed\n", tx ? "TX" : "RX");
> > +               return;
> > +       }
> > +
> > +       if (!result->residue) {
> > +               if (tx)
> > +                       complete(&gsi->mas->tx_cb);
> > +               else
> > +                       complete(&gsi->mas->rx_cb);
> > +       } else {
> > +               dev_err(gsi->mas->dev, "%s DMA txn has pending %d data\n",
> > +                       tx ? "TX" : "RX", result->residue);
> 
> I guess you just wait for the timeout in this case since you don't complete?

> > +static int setup_gsi_xfer(struct spi_transfer *xfer, struct spi_geni_master *mas,
> > +                         struct spi_device *spi_slv, struct spi_master *spi)
> > +{
> > +       unsigned long flags = DMA_PREP_INTERRUPT | DMA_CTRL_ACK;
> > +       struct spi_geni_gsi *gsi;
> > +       struct dma_slave_config config = {};
> > +       struct gpi_spi_config peripheral = {};
> > +       unsigned long timeout, jiffies;
> 
> Is it really a good idea to have a local variable called "jiffies"?
> Isn't the global called "jiffies"?

removed now

> > +       int ret, i;
> > +
> > +       config.peripheral_config = &peripheral;
> > +       config.peripheral_size = sizeof(peripheral);
> > +       peripheral.set_config = true;
> > +
> > +       if (xfer->bits_per_word != mas->cur_bits_per_word ||
> > +           xfer->speed_hz != mas->cur_speed_hz) {
> > +               mas->cur_bits_per_word = xfer->bits_per_word;
> > +               mas->cur_speed_hz = xfer->speed_hz;
> > +       }
> 
> It seems a bit pointless to copy these things into "mas" for GSI mode
> and even more pointless to have the "if" test first.
> 
> In FIFO mode I believe we stored them in "mas" because we needed them
> from the interrupt handler. It also lets us optimize and avoid calls
> if the config didn't change. You don't need them for either of these
> reasons, do you?

agreed, cleaned that up

> Actually, you might possibly want to keep "cur_speed_hz" and use it to
> avoid a call to get_spi_clk_cfg() which, at least at one point in
> time, was a bit slow.

Okay, thanks for suggestion, I can do that.

> > +       if (!(mas->cur_bits_per_word % MIN_WORD_LEN)) {
> > +               peripheral.rx_len = ((xfer->len << 3) / mas->cur_bits_per_word);
> > +       } else {
> > +               int bytes_per_word = (mas->cur_bits_per_word / BITS_PER_BYTE) + 1;
> > +
> > +               peripheral.rx_len = (xfer->len / bytes_per_word);
> > +       }
> 
> I guess you could only do the above if "rx_buf" and then you don't
> have to zero it back out below.

yes updated

> > +       if (xfer->tx_buf && xfer->rx_buf) {
> > +               peripheral.cmd = SPI_DUPLEX;
> > +       } else if (xfer->tx_buf) {
> > +               peripheral.cmd = SPI_TX;
> > +               peripheral.rx_len = 0;
> > +       } else if (xfer->rx_buf) {
> > +               peripheral.cmd = SPI_RX;
> > +       }
> > +
> > +       if (spi_slv->mode & SPI_LOOP)
> > +               peripheral.loopback_en = true;
> > +       if (spi_slv->mode & SPI_CPOL)
> > +               peripheral.clock_pol_high = true;
> > +       if (spi_slv->mode & SPI_CPHA)
> > +               peripheral.data_pol_high = true;
> 
> nit: I'd do it without the "if"s.
> 
> peripheral.loopback_en = spi_slv->mode & SPI_LOOP;

Good suggestion, updated now.

> In theory much of this could also be done at function init time but I
> dunno if it makes a huge difference, like:
> 
> struct gpi_spi_config peripheral = {
>   .loopback_en = spi_slv->mode & SPI_LOOP,
>   .clock_pol_high = spi_slv->mode & SPI_CPOL,
>   ...
> };

Still kept it runtime, lets me know in next rev if we can do better :)

> > +       peripheral.cs = spi_slv->chip_select;
> > +       peripheral.pack_en = true;
> > +       peripheral.word_len = xfer->bits_per_word - MIN_WORD_LEN;
> > +       peripheral.fragmentation = FRAGMENTATION;
> > +
> > +       ret = get_spi_clk_cfg(mas->cur_speed_hz, mas,
> > +                             &peripheral.clk_src, &peripheral.clk_div);
> > +       if (ret) {
> > +               dev_err(mas->dev, "Err in get_spi_clk_cfg() :%d\n", ret);
> > +               return ret;
> > +       }
> > +
> > +       gsi = &mas->gsi[mas->num_xfers];
> 
> It sure feels like you should error-check this against NUM_SPI_XFER.
> Otherwise if someone does a transfer with more than 8 parts you're
> totally hosed, right?
> 
> Actually, why do you even need an array here? It seems like by the
> time this function exits the transfer will be all done, right? So you
> can just keep using the same structure over and over again? It can
> even be on the stack?

This was the trigger so things are on stack now and cleaned, pls see
next rev, should be out in next few days

> > +       gsi->rx_cb.mas = mas;
> > +       gsi->rx_cb.xfer = xfer;
> > +
> > +       if (peripheral.cmd & SPI_RX) {
> > +               dmaengine_slave_config(mas->rx, &config);
> > +               gsi->rx_desc = dmaengine_prep_slave_sg(mas->rx, xfer->rx_sg.sgl, xfer->rx_sg.nents,
> > +                                                      DMA_DEV_TO_MEM, flags);
> > +               if (!gsi->rx_desc) {
> > +                       dev_err(mas->dev, "Err setting up rx desc\n");
> > +                       return -EIO;
> > +               }
> > +               gsi->rx_desc->callback_result = spi_gsi_rx_callback_result;
> > +               gsi->rx_desc->callback_param = &gsi->rx_cb;
> > +       }
> > +
> > +       dmaengine_slave_config(mas->tx, &config);
> > +       gsi->tx_desc = dmaengine_prep_slave_sg(mas->tx, xfer->tx_sg.sgl, xfer->tx_sg.nents,
> > +                                              DMA_MEM_TO_DEV, flags);
> > +       if (!gsi->tx_desc) {
> > +               dev_err(mas->dev, "Err setting up tx desc\n");
> > +               return -EIO;
> > +       }
> 
> I haven't dug deeply, but it surprises me that we do all the TX config
> even if "xfer->tx_buf" is NULL.

GPI DMA :) We _always_ need TX even for RX. I am adding a note here for
that

> > +       gsi->tx_cb.mas = mas;
> > +       gsi->tx_cb.xfer = xfer;
> > +       gsi->tx_desc->callback_result = spi_gsi_tx_callback_result;
> > +       gsi->tx_desc->callback_param = &gsi->tx_cb;
> > +
> > +       if (peripheral.cmd & SPI_RX)
> > +               gsi->rx_cookie = dmaengine_submit(gsi->rx_desc);
> > +       gsi->tx_cookie = dmaengine_submit(gsi->tx_desc);
> > +
> > +       if (peripheral.cmd & SPI_RX)
> > +               dma_async_issue_pending(mas->rx);
> > +       dma_async_issue_pending(mas->tx);
> > +       mas->num_xfers++;
> > +
> > +       jiffies = msecs_to_jiffies(SPI_XFER_TIMEOUT_MS);
> > +       timeout = wait_for_completion_timeout(&mas->tx_cb, jiffies);
> 
> You're waiting a hardcoded 250 ms for every transfer. That could be
> too short for a long transfer. Can you use some logic like the SPI
> framework?
> 
> It's probably also worth adding a comment about why you can't just
> return "1" from transfer_one() for GSI mode and let the SPI framework
> handle the timeout calculations. My guess is that you might need extra
> time because another processor might hold the SPI bus and keep you
> from starting your transfer right away and thus your timeout needs to
> be somehow longer than the normal SPI framework. Is that true?
> 
> Actually, it looks like spi_transfer_wait() already has 200 ms of
> slop. Is that enough for you? Can you just let the SPI framework
> handle the timeout?

I have removed the code and returned 1 :)

> 
> > +       if (timeout <= 0) {
> 
> Just "== 0". "timeout" is unsigned, right?
> 
> 
> > +               dev_err(mas->dev, "Tx[%d] timeout%lu\n", i, timeout);
> 
> timeout is always 0 in this printout.
> > +               ret = -ETIMEDOUT;
> > +               goto err_gsi_geni_transfer_one;
> > +       }
> > +
> > +       if (peripheral.cmd & SPI_RX) {
> > +               jiffies = msecs_to_jiffies(SPI_XFER_TIMEOUT_MS);
> > +               timeout = wait_for_completion_timeout(&mas->rx_cb, jiffies);
> 
> Why do you need to re-init the timeout? You should just wait for
> however much is left from the previous wait? The TX and RX should be
> happening in parallel, right? So you don't want to wait for a full
> second transfer.
> 
> > +               if (timeout <= 0) {
> > +                       dev_err(mas->dev, "Rx[%d] timeout%lu\n", i, timeout);
> > +                       ret = -ETIMEDOUT;
> > +                       goto err_gsi_geni_transfer_one;
> > +               }
> > +       }
> > +
> > +       spi_finalize_current_transfer(spi);
> > +       return 0;
> > +
> > +err_gsi_geni_transfer_one:
> > +       dmaengine_terminate_all(mas->tx);
> 
> I know not what I'm talking about, but the description of
> dmaengine_terminate_all says "This function is DEPRECATED". It also
> seems like the old "terminate_all" is async? That's bad because you
> gave it stack pointers...
> 
> You almost certainly want a WARN_ON or something like that if you fail
> to terminate the transfer because, presumably, the DMA engine will
> keep looking at your config that's stored on the stack (that you're
> freeing by ending the function). That's super bad and I'd want a
> pretty serious warning in my logs if it might be happening.

Oops, somehow this got missed, we are supposed to use
dmaengine_terminate_sync() here... I think I have updated i2c one but
missed here

> > +static bool geni_can_dma(struct spi_controller *ctlr,
> > +                        struct spi_device *slv, struct spi_transfer *xfer)
> > +{
> > +       struct spi_geni_master *mas = spi_master_get_devdata(slv->master);
> > +
> > +       /* check if dma is supported */
> > +       if (mas->cur_xfer_mode == GENI_GPI_DMA)
> > +               return true;
> > +
> > +       return false;
> > +}
> 
> nit: might as well handle GENI_SE_DMA as well since it's just as easy
> to test against GENI_SE_FIFO?

I think I will leave that for the person adding GENI_SE_DMA support :)

> nit: no need for an if.
> 
> So just: return mas->cur_xfer_mode != GENI_SE_FIFO;

Done

> >  static int spi_geni_prepare_message(struct spi_master *spi,
> >                                         struct spi_message *spi_msg)
> >  {
> > -       int ret;
> >         struct spi_geni_master *mas = spi_master_get_devdata(spi);
> > +       int ret;
> >
> > -       if (spi_geni_is_abort_still_pending(mas))
> > -               return -EBUSY;
> > +       switch (mas->cur_xfer_mode) {
> > +       case GENI_SE_FIFO:
> > +               if (spi_geni_is_abort_still_pending(mas))
> > +                       return -EBUSY;
> > +               ret = setup_fifo_params(spi_msg->spi, spi);
> > +               if (ret)
> > +                       dev_err(mas->dev, "Couldn't select mode %d\n", ret);
> > +               return ret;
> >
> > -       ret = setup_fifo_params(spi_msg->spi, spi);
> > -       if (ret)
> > -               dev_err(mas->dev, "Couldn't select mode %d\n", ret);
> > +       case GENI_GPI_DMA:
> > +               mas->num_xfers = 0;
> > +               reinit_completion(&mas->tx_cb);
> > +               reinit_completion(&mas->rx_cb);
> > +               memset(mas->gsi, 0, (sizeof(struct spi_geni_gsi) * NUM_SPI_XFER));
> 
> nit: make a #define for the size and use it here and in allocation?

Removed the struct so no longer needed

> > +static int spi_geni_grab_gpi_chan(struct spi_geni_master *mas)
> > +{
> > +       size_t gsi_sz;
> > +       int ret;
> > +
> > +       mas->tx = dma_request_chan(mas->dev, "tx");
> > +       if (IS_ERR_OR_NULL(mas->tx)) {
> 
> I don't think dma_request_chan() can return NULL.

No it cant, updated now!

> 
> 
> > +               dev_err(mas->dev, "Failed to get tx DMA ch %ld", PTR_ERR(mas->tx));
> > +               ret = PTR_ERR(mas->tx);
> 
> niftier: ret = dev_err_probe(mas->dev, PTR_ERR(mas->tx), "Failed to
> get tx DMA ch\n");
> 
> If you don't think that's nifty, at least you should add a "\n" to
> your error message.

I like dev_err_probe(), updated along with missing "\n"
> 
> 
> > +               goto err_tx;
> > +       }
> 
> Personally I'm a fan of devm_add_action_or_reset() to simplify error
> handling like this. Everything becomes easier to handle then.
> 
> ret = devm_add_action_or_reset(mas->dev, spi_geni_dma_release_chan, mas->tx);
> if (ret)
>   return ret;
> 
> You've got to make a tiny spi_geni_dma_release_chan() function that
> just wraps dma_release_chan() (or cast and violate the C standard) but
> then you get rid of all error handling in this function, get rid of
> the code you had to add to remove and the code you forgot to add the
> the probe() function (see below). :-)

So after reworking code, there is little error handling, so I am
skipping it for next rev

> > +       mas->rx = dma_request_chan(mas->dev, "rx");
> > +       if (IS_ERR_OR_NULL(mas->rx)) {
> > +               dev_err(mas->dev, "Failed to get rx DMA ch %ld", PTR_ERR(mas->rx));
> > +               ret = PTR_ERR(mas->rx);
> > +               goto err_rx;
> > +       }
> > +
> > +       gsi_sz = sizeof(struct spi_geni_gsi) * NUM_SPI_XFER;
> > +       mas->gsi = devm_kzalloc(mas->dev, gsi_sz, GFP_KERNEL);
> > +       if (IS_ERR_OR_NULL(mas->gsi))
> > +               goto err_mem;
> 
> This is not correct. kzalloc() never returns errors, just NULL. ...and
> you don't set "ret".
> 
> Also: since you re-use this over and over and zero it before each
> transfer, you could probably avoid the zero-allocation.
> 
> 
> > @@ -349,15 +594,15 @@ static int spi_geni_init(struct spi_geni_master *mas)
> >  {
> >         struct geni_se *se = &mas->se;
> >         unsigned int proto, major, minor, ver;
> > -       u32 spi_tx_cfg;
> > +       u32 spi_tx_cfg, fifo_disable;
> > +       int ret = -ENXIO;
> >
> >         pm_runtime_get_sync(mas->dev);
> >
> >         proto = geni_se_read_proto(se);
> >         if (proto != GENI_SE_SPI) {
> >                 dev_err(mas->dev, "Invalid proto %d\n", proto);
> > -               pm_runtime_put(mas->dev);
> > -               return -ENXIO;
> > +               goto out_pm;
> 
> nit: In theory this change could be relegated to a tiny cleanup patch
> just to make your GPI change smaller to review, but I won't insist.

This is looking better in next rev :)

> > @@ -380,15 +625,38 @@ static int spi_geni_init(struct spi_geni_master *mas)
> >         else
> >                 mas->oversampling = 1;
> >
> > -       geni_se_select_mode(se, GENI_SE_FIFO);
> > +       fifo_disable = readl(se->base + GENI_IF_DISABLE_RO) & FIFO_IF_DISABLE;
> > +       switch (fifo_disable) {
> > +       case 1:
> > +               ret = spi_geni_grab_gpi_chan(mas);
> > +               if (!ret) { /* success case */
> > +                       mas->cur_xfer_mode = GENI_GPI_DMA;
> > +                       geni_se_select_mode(se, GENI_GPI_DMA);
> > +                       dev_dbg(mas->dev, "Using GPI DMA mode for SPI\n");
> > +                       break;
> > +               }
> > +               /*
> > +                * in case of failure to get dma channel, we can till do the
> > +                * FIFO mode, so fallthrough
> 
> s/till/still/

ack

> 
> > +                */
> > +               dev_warn(mas->dev, "FIFO mode disabled, but couldn't get DMA, fall back to FIFO mode\n");
> > +               fallthrough;
> 
> I was under the impression that if `FIFO_IF_DISABLE` was set that the
> FIFO was, how shall we say it, "disabled". ;-) If you can in fact fall
> back to FIFO mode then that bit seems pretty poorly named.

So on few places I have seen fall back work and some it doesn't so name
seems correct. Now the question is should we _try_ to fallback on
disabled fifo or not.. :)

> >  static irqreturn_t geni_spi_isr(int irq, void *data)
> > @@ -671,6 +942,15 @@ static int spi_geni_probe(struct platform_device *pdev)
> >         if (irq < 0)
> >                 return irq;
> >
> > +       ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
> 
> nit: this function already has the line:
> 
> struct device *dev = &pdev->dev;
> 
> ...so you can use "dev". :-)

updated here and few more places


> 
> 
> > +       if (ret) {
> > +               ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
> > +               if (ret) {
> > +                       dev_err(&pdev->dev, "could not set DMA mask\n");
> > +                       return ret;
> 
> niftier: return dev_err_probe(dev, ret, "could not set DMA mask\n");
> 
> 
> > @@ -710,14 +990,17 @@ static int spi_geni_probe(struct platform_device *pdev)
> >         spi->max_speed_hz = 50000000;
> >         spi->prepare_message = spi_geni_prepare_message;
> >         spi->transfer_one = spi_geni_transfer_one;
> > +       spi->can_dma = geni_can_dma;
> > +       spi->dma_map_dev = mas->dev->parent;
> 
> mas->dev->parent == dev->parent ?
> 
> 
> > @@ -738,6 +1021,14 @@ static int spi_geni_probe(struct platform_device *pdev)
> >         if (ret)
> >                 goto spi_geni_probe_runtime_disable;
> >
> > +       /*
> > +        * check the mode supported and set_cs for fifo mode only
> > +        * for dma (gsi) mode, the gsi will set cs based on params passed in
> > +        * TRE
> > +        */
> > +       if (mas->cur_xfer_mode == GENI_SE_FIFO)
> > +               spi->set_cs = spi_geni_set_cs;
> 
> I'm curious: is there no way to get set_cs() working in GPI mode? In
> an off-thread conversation Qualcomm seemed to indicate that it was
> possible, but maybe they didn't quite understand what I was asking.
> 
> Without an implementation of set_cs() there will be drivers in Linux
> that simply aren't compatible because they make the assumption that
> they can lock the bus, set the CS, and do several transfers that are
> part of some logical "transaction". I believe that both of the SPI
> peripherals on boards that I work on, cros-ec and the SPI TPM make
> this assumption. I don't even believe that the drivers can be "fixed"
> because the requirement is more at the protocol level. The protocol
> requires you to do things like:
> 
> 0. Lock the bus.
> 1. Set the CS.
> 2. Transfer a few bytes, reading the response as you go.
> 3. Once you see the other side respond that it's ready, transfer some
> more bytes.
> 4. Release the CS.
> 5. Unlock the bus.
> 
> You can't do this without a set_cs() implementation because of the
> requirement to read the responses of the other side before moving on
> to the next phase of the transfer.
> 
> As I understand it this is roughly the equivalent of i2c clock
> stretching but much more ad-hoc and defined peripherals-by-peripheral.
> 
> In any case, I guess you must have examples of peripherals that need
> GPI mode and don't need set_cs() so we shouldn't block your way
> forward, but I'm just curious if you had more info on this.

So I have asked some qcom folks, they tell me it is _possible_ to use
the cs bit in the TRE and it can work. But TBH I am not yet convinced it
would work as advertised. So do you enable the GPI mode for chrome books
or it is SE DMA mode (i think SE DMA mode might be simpler to use for
your case)

> 
> 
> >  static int spi_geni_remove(struct platform_device *pdev)
> >  {
> >         struct spi_master *spi = platform_get_drvdata(pdev);
> > @@ -762,6 +1061,8 @@ static int spi_geni_remove(struct platform_device *pdev)
> >         /* Unregister _before_ disabling pm_runtime() so we stop transfers */
> >         spi_unregister_master(spi);
> >
> > +       spi_geni_release_dma_chan(mas);
> > +
> 
> Why isn't there a call to spi_geni_release_dma_chan() in the error
> paths for probe?

Fixed
Doug Anderson Oct. 14, 2021, 4:55 p.m. UTC | #4
Hi,


On Thu, Oct 14, 2021 at 9:04 AM Vinod Koul <vkoul@kernel.org> wrote:
> > > +static bool geni_can_dma(struct spi_controller *ctlr,
> > > +                        struct spi_device *slv, struct spi_transfer *xfer)
> > > +{
> > > +       struct spi_geni_master *mas = spi_master_get_devdata(slv->master);
> > > +
> > > +       /* check if dma is supported */
> > > +       if (mas->cur_xfer_mode == GENI_GPI_DMA)
> > > +               return true;
> > > +
> > > +       return false;
> > > +}
> >
> > nit: might as well handle GENI_SE_DMA as well since it's just as easy
> > to test against GENI_SE_FIFO?
>
> I think I will leave that for the person adding GENI_SE_DMA support :)

I was just thinking of changing the "if" statement:

if (mas->cur_xfer_mode != GENI_SE_FIFO)

It's no skin off your teeth and would make one fewer line to change
if/when the other DMA mode is supported. In any case, I won't push it.
;-)


> > > @@ -738,6 +1021,14 @@ static int spi_geni_probe(struct platform_device *pdev)
> > >         if (ret)
> > >                 goto spi_geni_probe_runtime_disable;
> > >
> > > +       /*
> > > +        * check the mode supported and set_cs for fifo mode only
> > > +        * for dma (gsi) mode, the gsi will set cs based on params passed in
> > > +        * TRE
> > > +        */
> > > +       if (mas->cur_xfer_mode == GENI_SE_FIFO)
> > > +               spi->set_cs = spi_geni_set_cs;
> >
> > I'm curious: is there no way to get set_cs() working in GPI mode? In
> > an off-thread conversation Qualcomm seemed to indicate that it was
> > possible, but maybe they didn't quite understand what I was asking.
> >
> > Without an implementation of set_cs() there will be drivers in Linux
> > that simply aren't compatible because they make the assumption that
> > they can lock the bus, set the CS, and do several transfers that are
> > part of some logical "transaction". I believe that both of the SPI
> > peripherals on boards that I work on, cros-ec and the SPI TPM make
> > this assumption. I don't even believe that the drivers can be "fixed"
> > because the requirement is more at the protocol level. The protocol
> > requires you to do things like:
> >
> > 0. Lock the bus.
> > 1. Set the CS.
> > 2. Transfer a few bytes, reading the response as you go.
> > 3. Once you see the other side respond that it's ready, transfer some
> > more bytes.
> > 4. Release the CS.
> > 5. Unlock the bus.
> >
> > You can't do this without a set_cs() implementation because of the
> > requirement to read the responses of the other side before moving on
> > to the next phase of the transfer.
> >
> > As I understand it this is roughly the equivalent of i2c clock
> > stretching but much more ad-hoc and defined peripherals-by-peripheral.
> >
> > In any case, I guess you must have examples of peripherals that need
> > GPI mode and don't need set_cs() so we shouldn't block your way
> > forward, but I'm just curious if you had more info on this.
>
> So I have asked some qcom folks, they tell me it is _possible_ to use
> the cs bit in the TRE and it can work. But TBH I am not yet convinced it
> would work as advertised. So do you enable the GPI mode for chrome books
> or it is SE DMA mode (i think SE DMA mode might be simpler to use for
> your case)

Sounds promising. I'm curious about why you're not convinced it would
work as advertised? Right now we have all our SPI devices running in
FIFO mode (!) and we've been trying to find a way to get them in DMA
mode. I think Qualcomm is trying to avoid supporting both SE DMA and
GPI DMA mode so they are saying that once GPI mode works then we can
just use that.

I don't really have a huge objection to that, but I also have zero
experience with GPI DMA mode. We don't have any need (at the moment)
to share our SPI bus with multiple execution environments, but it
seems like GPI mode _could_ still work as long as the chip select
problem is solved. I did manage to get some more documentation and I
do see a "LOCK" command, so maybe that combined with leaving the CS
asserted would solve the problem? Maybe Mark would allow your driver
to get called from spi_bus_lock() and spi_bus_unlock(). That seems
like it would be important to do anyway to match the Linux SPI client
model...

NOTE: in reality, we sorta paper over the "chip select" problem anyway
on Chromebooks. We just configure the chip select lines as GPIOs and
let Linux manage them. There is much less overhead in setting a GPIO
compared to messaging a QUP, so this improves performance. As long as
this continues to work, perhaps we don't care about whether we can
really tell GPI mode to leave the CS asserted.

-Doug
Vinod Koul Oct. 18, 2021, 4:53 p.m. UTC | #5
Hi,

On 14-10-21, 09:55, Doug Anderson wrote:
> On Thu, Oct 14, 2021 at 9:04 AM Vinod Koul <vkoul@kernel.org> wrote:
> > > > +static bool geni_can_dma(struct spi_controller *ctlr,
> > > > +                        struct spi_device *slv, struct spi_transfer *xfer)
> > > > +{
> > > > +       struct spi_geni_master *mas = spi_master_get_devdata(slv->master);
> > > > +
> > > > +       /* check if dma is supported */
> > > > +       if (mas->cur_xfer_mode == GENI_GPI_DMA)
> > > > +               return true;
> > > > +
> > > > +       return false;
> > > > +}
> > >
> > > nit: might as well handle GENI_SE_DMA as well since it's just as easy
> > > to test against GENI_SE_FIFO?
> >
> > I think I will leave that for the person adding GENI_SE_DMA support :)
> 
> I was just thinking of changing the "if" statement:
> 
> if (mas->cur_xfer_mode != GENI_SE_FIFO)
> 
> It's no skin off your teeth and would make one fewer line to change
> if/when the other DMA mode is supported. In any case, I won't push it.
> ;-)

I can do that!

> > > > @@ -738,6 +1021,14 @@ static int spi_geni_probe(struct platform_device *pdev)
> > > >         if (ret)
> > > >                 goto spi_geni_probe_runtime_disable;
> > > >
> > > > +       /*
> > > > +        * check the mode supported and set_cs for fifo mode only
> > > > +        * for dma (gsi) mode, the gsi will set cs based on params passed in
> > > > +        * TRE
> > > > +        */
> > > > +       if (mas->cur_xfer_mode == GENI_SE_FIFO)
> > > > +               spi->set_cs = spi_geni_set_cs;
> > >
> > > I'm curious: is there no way to get set_cs() working in GPI mode? In
> > > an off-thread conversation Qualcomm seemed to indicate that it was
> > > possible, but maybe they didn't quite understand what I was asking.

I dont think so, as the GPI firmware controls CS here. IIRC set_cs() was
causing issues with gpi mode

> > > Without an implementation of set_cs() there will be drivers in Linux
> > > that simply aren't compatible because they make the assumption that
> > > they can lock the bus, set the CS, and do several transfers that are
> > > part of some logical "transaction". I believe that both of the SPI
> > > peripherals on boards that I work on, cros-ec and the SPI TPM make
> > > this assumption. I don't even believe that the drivers can be "fixed"
> > > because the requirement is more at the protocol level. The protocol
> > > requires you to do things like:
> > >
> > > 0. Lock the bus.
> > > 1. Set the CS.
> > > 2. Transfer a few bytes, reading the response as you go.
> > > 3. Once you see the other side respond that it's ready, transfer some
> > > more bytes.
> > > 4. Release the CS.
> > > 5. Unlock the bus.
> > >
> > > You can't do this without a set_cs() implementation because of the
> > > requirement to read the responses of the other side before moving on
> > > to the next phase of the transfer.
> > >
> > > As I understand it this is roughly the equivalent of i2c clock
> > > stretching but much more ad-hoc and defined peripherals-by-peripheral.
> > >
> > > In any case, I guess you must have examples of peripherals that need
> > > GPI mode and don't need set_cs() so we shouldn't block your way
> > > forward, but I'm just curious if you had more info on this.

Yes, I am testing with CAN bus on Rb3.

> > So I have asked some qcom folks, they tell me it is _possible_ to use
> > the cs bit in the TRE and it can work. But TBH I am not yet convinced it
> > would work as advertised. So do you enable the GPI mode for chrome books
> > or it is SE DMA mode (i think SE DMA mode might be simpler to use for
> > your case)
> 
> Sounds promising. I'm curious about why you're not convinced it would
> work as advertised? Right now we have all our SPI devices running in
> FIFO mode (!) and we've been trying to find a way to get them in DMA
> mode. I think Qualcomm is trying to avoid supporting both SE DMA and
> GPI DMA mode so they are saying that once GPI mode works then we can
> just use that.
> 
> I don't really have a huge objection to that, but I also have zero
> experience with GPI DMA mode. We don't have any need (at the moment)
> to share our SPI bus with multiple execution environments, but it
> seems like GPI mode _could_ still work as long as the chip select
> problem is solved. I did manage to get some more documentation and I
> do see a "LOCK" command, so maybe that combined with leaving the CS
> asserted would solve the problem? Maybe Mark would allow your driver
> to get called from spi_bus_lock() and spi_bus_unlock(). That seems
> like it would be important to do anyway to match the Linux SPI client
> model...

We can add lock support, but IIUC it was to prevent other EEs from
running, it may not help with chip select. It also needs someone loading
firmware on the controller.

For us, since some boards are shipping with firmware loaded, fifo and se
dma mode will not work, only option is to get gpi mode working.

> NOTE: in reality, we sorta paper over the "chip select" problem anyway
> on Chromebooks. We just configure the chip select lines as GPIOs and
> let Linux manage them. There is much less overhead in setting a GPIO
> compared to messaging a QUP, so this improves performance. As long as
> this continues to work, perhaps we don't care about whether we can
> really tell GPI mode to leave the CS asserted.

I think it would be good experiment to get it working with chromebooks.
I am sure it wont be trivial and may not work out of box, but would be a
good experiment to do :)
diff mbox series

Patch

diff --git a/drivers/spi/spi-geni-qcom.c b/drivers/spi/spi-geni-qcom.c
index 3d0d8ddd5772..c64355c246be 100644
--- a/drivers/spi/spi-geni-qcom.c
+++ b/drivers/spi/spi-geni-qcom.c
@@ -2,6 +2,9 @@ 
 // Copyright (c) 2017-2018, The Linux foundation. All rights reserved.
 
 #include <linux/clk.h>
+#include <linux/dmaengine.h>
+#include <linux/dma-mapping.h>
+#include <linux/dma/qcom-gpi-dma.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/log2.h>
@@ -63,6 +66,29 @@ 
 #define TIMESTAMP_AFTER		BIT(3)
 #define POST_CMD_DELAY		BIT(4)
 
+#define GSI_LOOPBACK_EN		(BIT(0))
+#define GSI_CS_TOGGLE		(BIT(3))
+#define GSI_CPHA		(BIT(4))
+#define GSI_CPOL		(BIT(5))
+
+#define MAX_TX_SG		(3)
+#define NUM_SPI_XFER		(8)
+#define SPI_XFER_TIMEOUT_MS	(250)
+
+struct gsi_desc_cb {
+	struct spi_geni_master *mas;
+	struct spi_transfer *xfer;
+};
+
+struct spi_geni_gsi {
+	dma_cookie_t tx_cookie;
+	dma_cookie_t rx_cookie;
+	struct dma_async_tx_descriptor *tx_desc;
+	struct dma_async_tx_descriptor *rx_desc;
+	struct gsi_desc_cb tx_cb;
+	struct gsi_desc_cb rx_cb;
+};
+
 struct spi_geni_master {
 	struct geni_se se;
 	struct device *dev;
@@ -84,6 +110,13 @@  struct spi_geni_master {
 	int irq;
 	bool cs_flag;
 	bool abort_failed;
+	struct spi_geni_gsi *gsi;
+	struct dma_chan *tx;
+	struct dma_chan *rx;
+	struct completion tx_cb;
+	struct completion rx_cb;
+	int cur_xfer_mode;
+	int num_xfers;
 };
 
 static int get_spi_clk_cfg(unsigned int speed_hz,
@@ -330,18 +363,230 @@  static int setup_fifo_params(struct spi_device *spi_slv,
 	return geni_spi_set_clock_and_bw(mas, spi_slv->max_speed_hz);
 }
 
+static void
+spi_gsi_callback_result(void *cb, const struct dmaengine_result *result, bool tx)
+{
+	struct gsi_desc_cb *gsi = cb;
+
+	if (result->result != DMA_TRANS_NOERROR) {
+		dev_err(gsi->mas->dev, "%s DMA txn failed\n", tx ? "TX" : "RX");
+		return;
+	}
+
+	if (!result->residue) {
+		if (tx)
+			complete(&gsi->mas->tx_cb);
+		else
+			complete(&gsi->mas->rx_cb);
+	} else {
+		dev_err(gsi->mas->dev, "%s DMA txn has pending %d data\n",
+			tx ? "TX" : "RX", result->residue);
+	}
+}
+
+static void
+spi_gsi_rx_callback_result(void *cb, const struct dmaengine_result *result)
+{
+	spi_gsi_callback_result(cb, result, false);
+}
+
+static void
+spi_gsi_tx_callback_result(void *cb, const struct dmaengine_result *result)
+{
+	spi_gsi_callback_result(cb, result, true);
+}
+
+static int setup_gsi_xfer(struct spi_transfer *xfer, struct spi_geni_master *mas,
+			  struct spi_device *spi_slv, struct spi_master *spi)
+{
+	unsigned long flags = DMA_PREP_INTERRUPT | DMA_CTRL_ACK;
+	struct spi_geni_gsi *gsi;
+	struct dma_slave_config config = {};
+	struct gpi_spi_config peripheral = {};
+	unsigned long timeout, jiffies;
+	int ret, i;
+
+	config.peripheral_config = &peripheral;
+	config.peripheral_size = sizeof(peripheral);
+	peripheral.set_config = true;
+
+	if (xfer->bits_per_word != mas->cur_bits_per_word ||
+	    xfer->speed_hz != mas->cur_speed_hz) {
+		mas->cur_bits_per_word = xfer->bits_per_word;
+		mas->cur_speed_hz = xfer->speed_hz;
+	}
+
+	if (!(mas->cur_bits_per_word % MIN_WORD_LEN)) {
+		peripheral.rx_len = ((xfer->len << 3) / mas->cur_bits_per_word);
+	} else {
+		int bytes_per_word = (mas->cur_bits_per_word / BITS_PER_BYTE) + 1;
+
+		peripheral.rx_len = (xfer->len / bytes_per_word);
+	}
+
+	if (xfer->tx_buf && xfer->rx_buf) {
+		peripheral.cmd = SPI_DUPLEX;
+	} else if (xfer->tx_buf) {
+		peripheral.cmd = SPI_TX;
+		peripheral.rx_len = 0;
+	} else if (xfer->rx_buf) {
+		peripheral.cmd = SPI_RX;
+	}
+
+	if (spi_slv->mode & SPI_LOOP)
+		peripheral.loopback_en = true;
+	if (spi_slv->mode & SPI_CPOL)
+		peripheral.clock_pol_high = true;
+	if (spi_slv->mode & SPI_CPHA)
+		peripheral.data_pol_high = true;
+
+	peripheral.cs = spi_slv->chip_select;
+	peripheral.pack_en = true;
+	peripheral.word_len = xfer->bits_per_word - MIN_WORD_LEN;
+	peripheral.fragmentation = FRAGMENTATION;
+
+	ret = get_spi_clk_cfg(mas->cur_speed_hz, mas,
+			      &peripheral.clk_src, &peripheral.clk_div);
+	if (ret) {
+		dev_err(mas->dev, "Err in get_spi_clk_cfg() :%d\n", ret);
+		return ret;
+	}
+
+	gsi = &mas->gsi[mas->num_xfers];
+	gsi->rx_cb.mas = mas;
+	gsi->rx_cb.xfer = xfer;
+
+	if (peripheral.cmd & SPI_RX) {
+		dmaengine_slave_config(mas->rx, &config);
+		gsi->rx_desc = dmaengine_prep_slave_sg(mas->rx, xfer->rx_sg.sgl, xfer->rx_sg.nents,
+						       DMA_DEV_TO_MEM, flags);
+		if (!gsi->rx_desc) {
+			dev_err(mas->dev, "Err setting up rx desc\n");
+			return -EIO;
+		}
+		gsi->rx_desc->callback_result = spi_gsi_rx_callback_result;
+		gsi->rx_desc->callback_param = &gsi->rx_cb;
+	}
+
+	dmaengine_slave_config(mas->tx, &config);
+	gsi->tx_desc = dmaengine_prep_slave_sg(mas->tx, xfer->tx_sg.sgl, xfer->tx_sg.nents,
+					       DMA_MEM_TO_DEV, flags);
+	if (!gsi->tx_desc) {
+		dev_err(mas->dev, "Err setting up tx desc\n");
+		return -EIO;
+	}
+
+	gsi->tx_cb.mas = mas;
+	gsi->tx_cb.xfer = xfer;
+	gsi->tx_desc->callback_result = spi_gsi_tx_callback_result;
+	gsi->tx_desc->callback_param = &gsi->tx_cb;
+
+	if (peripheral.cmd & SPI_RX)
+		gsi->rx_cookie = dmaengine_submit(gsi->rx_desc);
+	gsi->tx_cookie = dmaengine_submit(gsi->tx_desc);
+
+	if (peripheral.cmd & SPI_RX)
+		dma_async_issue_pending(mas->rx);
+	dma_async_issue_pending(mas->tx);
+	mas->num_xfers++;
+
+	jiffies = msecs_to_jiffies(SPI_XFER_TIMEOUT_MS);
+	timeout = wait_for_completion_timeout(&mas->tx_cb, jiffies);
+	if (timeout <= 0) {
+		dev_err(mas->dev, "Tx[%d] timeout%lu\n", i, timeout);
+		ret = -ETIMEDOUT;
+		goto err_gsi_geni_transfer_one;
+	}
+
+	if (peripheral.cmd & SPI_RX) {
+		jiffies = msecs_to_jiffies(SPI_XFER_TIMEOUT_MS);
+		timeout = wait_for_completion_timeout(&mas->rx_cb, jiffies);
+		if (timeout <= 0) {
+			dev_err(mas->dev, "Rx[%d] timeout%lu\n", i, timeout);
+			ret = -ETIMEDOUT;
+			goto err_gsi_geni_transfer_one;
+		}
+	}
+
+	spi_finalize_current_transfer(spi);
+	return 0;
+
+err_gsi_geni_transfer_one:
+	dmaengine_terminate_all(mas->tx);
+	return ret;
+}
+
+static bool geni_can_dma(struct spi_controller *ctlr,
+			 struct spi_device *slv, struct spi_transfer *xfer)
+{
+	struct spi_geni_master *mas = spi_master_get_devdata(slv->master);
+
+	/* check if dma is supported */
+	if (mas->cur_xfer_mode == GENI_GPI_DMA)
+		return true;
+
+	return false;
+}
+
 static int spi_geni_prepare_message(struct spi_master *spi,
 					struct spi_message *spi_msg)
 {
-	int ret;
 	struct spi_geni_master *mas = spi_master_get_devdata(spi);
+	int ret;
 
-	if (spi_geni_is_abort_still_pending(mas))
-		return -EBUSY;
+	switch (mas->cur_xfer_mode) {
+	case GENI_SE_FIFO:
+		if (spi_geni_is_abort_still_pending(mas))
+			return -EBUSY;
+		ret = setup_fifo_params(spi_msg->spi, spi);
+		if (ret)
+			dev_err(mas->dev, "Couldn't select mode %d\n", ret);
+		return ret;
 
-	ret = setup_fifo_params(spi_msg->spi, spi);
-	if (ret)
-		dev_err(mas->dev, "Couldn't select mode %d\n", ret);
+	case GENI_GPI_DMA:
+		mas->num_xfers = 0;
+		reinit_completion(&mas->tx_cb);
+		reinit_completion(&mas->rx_cb);
+		memset(mas->gsi, 0, (sizeof(struct spi_geni_gsi) * NUM_SPI_XFER));
+
+		return 0;
+	}
+
+	dev_err(mas->dev, "Mode not supported %d", mas->cur_xfer_mode);
+	return -EINVAL;
+}
+
+static int spi_geni_grab_gpi_chan(struct spi_geni_master *mas)
+{
+	size_t gsi_sz;
+	int ret;
+
+	mas->tx = dma_request_chan(mas->dev, "tx");
+	if (IS_ERR_OR_NULL(mas->tx)) {
+		dev_err(mas->dev, "Failed to get tx DMA ch %ld", PTR_ERR(mas->tx));
+		ret = PTR_ERR(mas->tx);
+		goto err_tx;
+	}
+	mas->rx = dma_request_chan(mas->dev, "rx");
+	if (IS_ERR_OR_NULL(mas->rx)) {
+		dev_err(mas->dev, "Failed to get rx DMA ch %ld", PTR_ERR(mas->rx));
+		ret = PTR_ERR(mas->rx);
+		goto err_rx;
+	}
+
+	gsi_sz = sizeof(struct spi_geni_gsi) * NUM_SPI_XFER;
+	mas->gsi = devm_kzalloc(mas->dev, gsi_sz, GFP_KERNEL);
+	if (IS_ERR_OR_NULL(mas->gsi))
+		goto err_mem;
+	return 0;
+
+err_mem:
+	dma_release_channel(mas->rx);
+err_rx:
+	dma_release_channel(mas->tx);
+err_tx:
+	mas->tx = NULL;
+	mas->rx = NULL;
 	return ret;
 }
 
@@ -349,15 +594,15 @@  static int spi_geni_init(struct spi_geni_master *mas)
 {
 	struct geni_se *se = &mas->se;
 	unsigned int proto, major, minor, ver;
-	u32 spi_tx_cfg;
+	u32 spi_tx_cfg, fifo_disable;
+	int ret = -ENXIO;
 
 	pm_runtime_get_sync(mas->dev);
 
 	proto = geni_se_read_proto(se);
 	if (proto != GENI_SE_SPI) {
 		dev_err(mas->dev, "Invalid proto %d\n", proto);
-		pm_runtime_put(mas->dev);
-		return -ENXIO;
+		goto out_pm;
 	}
 	mas->tx_fifo_depth = geni_se_get_tx_fifo_depth(se);
 
@@ -380,15 +625,38 @@  static int spi_geni_init(struct spi_geni_master *mas)
 	else
 		mas->oversampling = 1;
 
-	geni_se_select_mode(se, GENI_SE_FIFO);
+	fifo_disable = readl(se->base + GENI_IF_DISABLE_RO) & FIFO_IF_DISABLE;
+	switch (fifo_disable) {
+	case 1:
+		ret = spi_geni_grab_gpi_chan(mas);
+		if (!ret) { /* success case */
+			mas->cur_xfer_mode = GENI_GPI_DMA;
+			geni_se_select_mode(se, GENI_GPI_DMA);
+			dev_dbg(mas->dev, "Using GPI DMA mode for SPI\n");
+			break;
+		}
+		/*
+		 * in case of failure to get dma channel, we can till do the
+		 * FIFO mode, so fallthrough
+		 */
+		dev_warn(mas->dev, "FIFO mode disabled, but couldn't get DMA, fall back to FIFO mode\n");
+		fallthrough;
+
+	case 0:
+		mas->cur_xfer_mode = GENI_SE_FIFO;
+		geni_se_select_mode(se, GENI_SE_FIFO);
+		ret = 0;
+		break;
+	}
 
 	/* We always control CS manually */
 	spi_tx_cfg = readl(se->base + SE_SPI_TRANS_CFG);
 	spi_tx_cfg &= ~CS_TOGGLE;
 	writel(spi_tx_cfg, se->base + SE_SPI_TRANS_CFG);
 
+out_pm:
 	pm_runtime_put(mas->dev);
-	return 0;
+	return ret;
 }
 
 static unsigned int geni_byte_per_fifo_word(struct spi_geni_master *mas)
@@ -575,8 +843,11 @@  static int spi_geni_transfer_one(struct spi_master *spi,
 	if (!xfer->len)
 		return 0;
 
-	setup_fifo_xfer(xfer, mas, slv->mode, spi);
-	return 1;
+	if (mas->cur_xfer_mode == GENI_SE_FIFO) {
+		setup_fifo_xfer(xfer, mas, slv->mode, spi);
+		return 1;
+	}
+	return setup_gsi_xfer(xfer, mas, slv, spi);
 }
 
 static irqreturn_t geni_spi_isr(int irq, void *data)
@@ -671,6 +942,15 @@  static int spi_geni_probe(struct platform_device *pdev)
 	if (irq < 0)
 		return irq;
 
+	ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(64));
+	if (ret) {
+		ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(32));
+		if (ret) {
+			dev_err(&pdev->dev, "could not set DMA mask\n");
+			return ret;
+		}
+	}
+
 	base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(base))
 		return PTR_ERR(base);
@@ -710,14 +990,17 @@  static int spi_geni_probe(struct platform_device *pdev)
 	spi->max_speed_hz = 50000000;
 	spi->prepare_message = spi_geni_prepare_message;
 	spi->transfer_one = spi_geni_transfer_one;
+	spi->can_dma = geni_can_dma;
+	spi->dma_map_dev = mas->dev->parent;
 	spi->auto_runtime_pm = true;
 	spi->handle_err = handle_fifo_timeout;
-	spi->set_cs = spi_geni_set_cs;
 	spi->use_gpio_descriptors = true;
 
 	init_completion(&mas->cs_done);
 	init_completion(&mas->cancel_done);
 	init_completion(&mas->abort_done);
+	init_completion(&mas->tx_cb);
+	init_completion(&mas->rx_cb);
 	spin_lock_init(&mas->lock);
 	pm_runtime_use_autosuspend(&pdev->dev);
 	pm_runtime_set_autosuspend_delay(&pdev->dev, 250);
@@ -738,6 +1021,14 @@  static int spi_geni_probe(struct platform_device *pdev)
 	if (ret)
 		goto spi_geni_probe_runtime_disable;
 
+	/*
+	 * check the mode supported and set_cs for fifo mode only
+	 * for dma (gsi) mode, the gsi will set cs based on params passed in
+	 * TRE
+	 */
+	if (mas->cur_xfer_mode == GENI_SE_FIFO)
+		spi->set_cs = spi_geni_set_cs;
+
 	ret = request_irq(mas->irq, geni_spi_isr, 0, dev_name(dev), spi);
 	if (ret)
 		goto spi_geni_probe_runtime_disable;
@@ -754,6 +1045,14 @@  static int spi_geni_probe(struct platform_device *pdev)
 	return ret;
 }
 
+static void spi_geni_release_dma_chan(struct spi_geni_master *mas)
+{
+	if (mas->rx)
+		dma_release_channel(mas->rx);
+	if (mas->tx)
+		dma_release_channel(mas->tx);
+}
+
 static int spi_geni_remove(struct platform_device *pdev)
 {
 	struct spi_master *spi = platform_get_drvdata(pdev);
@@ -762,6 +1061,8 @@  static int spi_geni_remove(struct platform_device *pdev)
 	/* Unregister _before_ disabling pm_runtime() so we stop transfers */
 	spi_unregister_master(spi);
 
+	spi_geni_release_dma_chan(mas);
+
 	free_irq(mas->irq, spi);
 	pm_runtime_disable(&pdev->dev);
 	return 0;