| Message ID | 7895cce04cd4d140fb519a02315a8309c4c3ebb5.1561756511.git.mchehab+samsung@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Convert misc-devices, i2c, w1, spi and some markdown files to ReST | expand |
On Fri, 28 Jun 2019 18:23:16 -0300 Mauro Carvalho Chehab <mchehab+samsung@kernel.org> wrote: > While there's one file there with briefily describes the uAPI, > the documentation was written just like most subsystems: focused > on kernel developers. So, add it together with driver-api books. > > Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> For the minimal touch on IIO. Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Thanks, > --- > Documentation/index.rst | 1 + > .../spi/{butterfly => butterfly.rst} | 44 ++++---- > Documentation/spi/index.rst | 23 ++++ > Documentation/spi/{pxa2xx => pxa2xx.rst} | 94 ++++++++-------- > .../spi/{spi-lm70llp => spi-lm70llp.rst} | 17 ++- > .../spi/{spi-sc18is602 => spi-sc18is602.rst} | 3 + > .../spi/{spi-summary => spi-summary.rst} | 103 ++++++++++-------- > Documentation/spi/{spidev => spidev.rst} | 30 +++-- > drivers/iio/dummy/iio_simple_dummy.c | 2 +- > drivers/spi/Kconfig | 2 +- > drivers/spi/spi-butterfly.c | 2 +- > drivers/spi/spi-lm70llp.c | 2 +- > include/linux/platform_data/sc18is602.h | 2 +- > 13 files changed, 198 insertions(+), 127 deletions(-) > rename Documentation/spi/{butterfly => butterfly.rst} (71%) > create mode 100644 Documentation/spi/index.rst > rename Documentation/spi/{pxa2xx => pxa2xx.rst} (83%) > rename Documentation/spi/{spi-lm70llp => spi-lm70llp.rst} (88%) > rename Documentation/spi/{spi-sc18is602 => spi-sc18is602.rst} (97%) > rename Documentation/spi/{spi-summary => spi-summary.rst} (93%) > rename Documentation/spi/{spidev => spidev.rst} (90%) > > diff --git a/Documentation/index.rst b/Documentation/index.rst > index 38ece18f5d1e..bcaddbfa817f 100644 > --- a/Documentation/index.rst > +++ b/Documentation/index.rst > @@ -115,6 +115,7 @@ needed). > power/index > target/index > timers/index > + spi/index > w1/index > watchdog/index > input/index > diff --git a/Documentation/spi/butterfly b/Documentation/spi/butterfly.rst > similarity index 71% > rename from Documentation/spi/butterfly > rename to Documentation/spi/butterfly.rst > index 9927af7a629c..e614a589547c 100644 > --- a/Documentation/spi/butterfly > +++ b/Documentation/spi/butterfly.rst > @@ -1,3 +1,4 @@ > +=================================================== > spi_butterfly - parport-to-butterfly adapter driver > =================================================== > > @@ -27,25 +28,29 @@ need to reflash the firmware, and the pins are the standard Atmel "ISP" > connector pins (used also on non-Butterfly AVR boards). On the parport > side this is like "sp12" programming cables. > > + ====== ============= =================== > Signal Butterfly Parport (DB-25) > - ------ --------- --------------- > - SCK = J403.PB1/SCK = pin 2/D0 > - RESET = J403.nRST = pin 3/D1 > - VCC = J403.VCC_EXT = pin 8/D6 > - MOSI = J403.PB2/MOSI = pin 9/D7 > - MISO = J403.PB3/MISO = pin 11/S7,nBUSY > - GND = J403.GND = pin 23/GND > + ====== ============= =================== > + SCK J403.PB1/SCK pin 2/D0 > + RESET J403.nRST pin 3/D1 > + VCC J403.VCC_EXT pin 8/D6 > + MOSI J403.PB2/MOSI pin 9/D7 > + MISO J403.PB3/MISO pin 11/S7,nBUSY > + GND J403.GND pin 23/GND > + ====== ============= =================== > > Then to let Linux master that bus to talk to the DataFlash chip, you must > (a) flash new firmware that disables SPI (set PRR.2, and disable pullups > by clearing PORTB.[0-3]); (b) configure the mtd_dataflash driver; and > (c) cable in the chipselect. > > + ====== ============ =================== > Signal Butterfly Parport (DB-25) > - ------ --------- --------------- > - VCC = J400.VCC_EXT = pin 7/D5 > - SELECT = J400.PB0/nSS = pin 17/C3,nSELECT > - GND = J400.GND = pin 24/GND > + ====== ============ =================== > + VCC J400.VCC_EXT pin 7/D5 > + SELECT J400.PB0/nSS pin 17/C3,nSELECT > + GND J400.GND pin 24/GND > + ====== ============ =================== > > Or you could flash firmware making the AVR into an SPI slave (keeping the > DataFlash in reset) and tweak the spi_butterfly driver to make it bind to > @@ -56,13 +61,14 @@ That would let you talk to the AVR using custom SPI-with-USI firmware, > while letting either Linux or the AVR use the DataFlash. There are plenty > of spare parport pins to wire this one up, such as: > > + ====== ============= =================== > Signal Butterfly Parport (DB-25) > - ------ --------- --------------- > - SCK = J403.PE4/USCK = pin 5/D3 > - MOSI = J403.PE5/DI = pin 6/D4 > - MISO = J403.PE6/DO = pin 12/S5,nPAPEROUT > - GND = J403.GND = pin 22/GND > - > - IRQ = J402.PF4 = pin 10/S6,ACK > - GND = J402.GND(P2) = pin 25/GND > + ====== ============= =================== > + SCK J403.PE4/USCK pin 5/D3 > + MOSI J403.PE5/DI pin 6/D4 > + MISO J403.PE6/DO pin 12/S5,nPAPEROUT > + GND J403.GND pin 22/GND > > + IRQ J402.PF4 pin 10/S6,ACK > + GND J402.GND(P2) pin 25/GND > + ====== ============= =================== > diff --git a/Documentation/spi/index.rst b/Documentation/spi/index.rst > new file mode 100644 > index 000000000000..bad6259a7bb6 > --- /dev/null > +++ b/Documentation/spi/index.rst > @@ -0,0 +1,23 @@ > +.. SPDX-License-Identifier: GPL-2.0 > + > +================================= > +Serial Peripheral Interface (SPI) > +================================= > + > +.. toctree:: > + :maxdepth: 1 > + > + spi-summary > + spidev > + butterfly > + pxa2xx > + spi-lm70llp > + spi-sc18is602 > + > +.. only:: subproject and html > + > + Indices > + ======= > + > + * :ref:`genindex` > + > diff --git a/Documentation/spi/pxa2xx b/Documentation/spi/pxa2xx.rst > similarity index 83% > rename from Documentation/spi/pxa2xx > rename to Documentation/spi/pxa2xx.rst > index 551325b66b23..457faef8be74 100644 > --- a/Documentation/spi/pxa2xx > +++ b/Documentation/spi/pxa2xx.rst > @@ -1,8 +1,10 @@ > +============================== > PXA2xx SPI on SSP driver HOWTO > -=================================================== > +============================== > + > This a mini howto on the pxa2xx_spi driver. The driver turns a PXA2xx > synchronous serial port into a SPI master controller > -(see Documentation/spi/spi-summary). The driver has the following features > +(see Documentation/spi/spi-summary.rst). The driver has the following features > > - Support for any PXA2xx SSP > - SSP PIO and SSP DMA data transfers. > @@ -19,12 +21,12 @@ Declaring PXA2xx Master Controllers > ----------------------------------- > Typically a SPI master is defined in the arch/.../mach-*/board-*.c as a > "platform device". The master configuration is passed to the driver via a table > -found in include/linux/spi/pxa2xx_spi.h: > +found in include/linux/spi/pxa2xx_spi.h:: > > -struct pxa2xx_spi_controller { > + struct pxa2xx_spi_controller { > u16 num_chipselect; > u8 enable_dma; > -}; > + }; > > The "pxa2xx_spi_controller.num_chipselect" field is used to determine the number of > slave device (chips) attached to this SPI master. > @@ -36,9 +38,9 @@ See the "PXA2xx Developer Manual" section "DMA Controller". > > NSSP MASTER SAMPLE > ------------------ > -Below is a sample configuration using the PXA255 NSSP. > +Below is a sample configuration using the PXA255 NSSP:: > > -static struct resource pxa_spi_nssp_resources[] = { > + static struct resource pxa_spi_nssp_resources[] = { > [0] = { > .start = __PREG(SSCR0_P(2)), /* Start address of NSSP */ > .end = __PREG(SSCR0_P(2)) + 0x2c, /* Range of registers */ > @@ -49,14 +51,14 @@ static struct resource pxa_spi_nssp_resources[] = { > .end = IRQ_NSSP, > .flags = IORESOURCE_IRQ, > }, > -}; > + }; > > -static struct pxa2xx_spi_controller pxa_nssp_master_info = { > + static struct pxa2xx_spi_controller pxa_nssp_master_info = { > .num_chipselect = 1, /* Matches the number of chips attached to NSSP */ > .enable_dma = 1, /* Enables NSSP DMA */ > -}; > + }; > > -static struct platform_device pxa_spi_nssp = { > + static struct platform_device pxa_spi_nssp = { > .name = "pxa2xx-spi", /* MUST BE THIS VALUE, so device match driver */ > .id = 2, /* Bus number, MUST MATCH SSP number 1..n */ > .resource = pxa_spi_nssp_resources, > @@ -64,22 +66,22 @@ static struct platform_device pxa_spi_nssp = { > .dev = { > .platform_data = &pxa_nssp_master_info, /* Passed to driver */ > }, > -}; > + }; > > -static struct platform_device *devices[] __initdata = { > + static struct platform_device *devices[] __initdata = { > &pxa_spi_nssp, > -}; > + }; > > -static void __init board_init(void) > -{ > + static void __init board_init(void) > + { > (void)platform_add_device(devices, ARRAY_SIZE(devices)); > -} > + } > > Declaring Slave Devices > ----------------------- > Typically each SPI slave (chip) is defined in the arch/.../mach-*/board-*.c > using the "spi_board_info" structure found in "linux/spi/spi.h". See > -"Documentation/spi/spi-summary" for additional information. > +"Documentation/spi/spi-summary.rst" for additional information. > > Each slave device attached to the PXA must provide slave specific configuration > information via the structure "pxa2xx_spi_chip" found in > @@ -87,19 +89,21 @@ information via the structure "pxa2xx_spi_chip" found in > will uses the configuration whenever the driver communicates with the slave > device. All fields are optional. > > -struct pxa2xx_spi_chip { > +:: > + > + struct pxa2xx_spi_chip { > u8 tx_threshold; > u8 rx_threshold; > u8 dma_burst_size; > u32 timeout; > u8 enable_loopback; > void (*cs_control)(u32 command); > -}; > + }; > > The "pxa2xx_spi_chip.tx_threshold" and "pxa2xx_spi_chip.rx_threshold" fields are > used to configure the SSP hardware fifo. These fields are critical to the > performance of pxa2xx_spi driver and misconfiguration will result in rx > -fifo overruns (especially in PIO mode transfers). Good default values are > +fifo overruns (especially in PIO mode transfers). Good default values are:: > > .tx_threshold = 8, > .rx_threshold = 8, > @@ -141,41 +145,43 @@ The pxa2xx_spi_chip structure is passed to the pxa2xx_spi driver in the > "spi_board_info.controller_data" field. Below is a sample configuration using > the PXA255 NSSP. > > -/* Chip Select control for the CS8415A SPI slave device */ > -static void cs8415a_cs_control(u32 command) > -{ > +:: > + > + /* Chip Select control for the CS8415A SPI slave device */ > + static void cs8415a_cs_control(u32 command) > + { > if (command & PXA2XX_CS_ASSERT) > GPCR(2) = GPIO_bit(2); > else > GPSR(2) = GPIO_bit(2); > -} > + } > > -/* Chip Select control for the CS8405A SPI slave device */ > -static void cs8405a_cs_control(u32 command) > -{ > + /* Chip Select control for the CS8405A SPI slave device */ > + static void cs8405a_cs_control(u32 command) > + { > if (command & PXA2XX_CS_ASSERT) > GPCR(3) = GPIO_bit(3); > else > GPSR(3) = GPIO_bit(3); > -} > + } > > -static struct pxa2xx_spi_chip cs8415a_chip_info = { > + static struct pxa2xx_spi_chip cs8415a_chip_info = { > .tx_threshold = 8, /* SSP hardward FIFO threshold */ > .rx_threshold = 8, /* SSP hardward FIFO threshold */ > .dma_burst_size = 8, /* Byte wide transfers used so 8 byte bursts */ > .timeout = 235, /* See Intel documentation */ > .cs_control = cs8415a_cs_control, /* Use external chip select */ > -}; > + }; > > -static struct pxa2xx_spi_chip cs8405a_chip_info = { > + static struct pxa2xx_spi_chip cs8405a_chip_info = { > .tx_threshold = 8, /* SSP hardward FIFO threshold */ > .rx_threshold = 8, /* SSP hardward FIFO threshold */ > .dma_burst_size = 8, /* Byte wide transfers used so 8 byte bursts */ > .timeout = 235, /* See Intel documentation */ > .cs_control = cs8405a_cs_control, /* Use external chip select */ > -}; > + }; > > -static struct spi_board_info streetracer_spi_board_info[] __initdata = { > + static struct spi_board_info streetracer_spi_board_info[] __initdata = { > { > .modalias = "cs8415a", /* Name of spi_driver for this device */ > .max_speed_hz = 3686400, /* Run SSP as fast a possbile */ > @@ -193,13 +199,13 @@ static struct spi_board_info streetracer_spi_board_info[] __initdata = { > .controller_data = &cs8405a_chip_info, /* Master chip config */ > .irq = STREETRACER_APCI_IRQ, /* Slave device interrupt */ > }, > -}; > + }; > > -static void __init streetracer_init(void) > -{ > + static void __init streetracer_init(void) > + { > spi_register_board_info(streetracer_spi_board_info, > ARRAY_SIZE(streetracer_spi_board_info)); > -} > + } > > > DMA and PIO I/O Support > @@ -210,22 +216,22 @@ by setting the "enable_dma" flag in the "pxa2xx_spi_controller" structure. The > mode supports both coherent and stream based DMA mappings. > > The following logic is used to determine the type of I/O to be used on > -a per "spi_transfer" basis: > +a per "spi_transfer" basis:: > > -if !enable_dma then > + if !enable_dma then > always use PIO transfers > > -if spi_message.len > 8191 then > + if spi_message.len > 8191 then > print "rate limited" warning > use PIO transfers > > -if spi_message.is_dma_mapped and rx_dma_buf != 0 and tx_dma_buf != 0 then > + if spi_message.is_dma_mapped and rx_dma_buf != 0 and tx_dma_buf != 0 then > use coherent DMA mode > > -if rx_buf and tx_buf are aligned on 8 byte boundary then > + if rx_buf and tx_buf are aligned on 8 byte boundary then > use streaming DMA mode > > -otherwise > + otherwise > use PIO transfer > > THANKS TO > diff --git a/Documentation/spi/spi-lm70llp b/Documentation/spi/spi-lm70llp.rst > similarity index 88% > rename from Documentation/spi/spi-lm70llp > rename to Documentation/spi/spi-lm70llp.rst > index 463f6d01fa15..07631aef4343 100644 > --- a/Documentation/spi/spi-lm70llp > +++ b/Documentation/spi/spi-lm70llp.rst > @@ -1,8 +1,11 @@ > +============================================== > spi_lm70llp : LM70-LLP parport-to-SPI adapter > ============================================== > > Supported board/chip: > + > * National Semiconductor LM70 LLP evaluation board > + > Datasheet: http://www.national.com/pf/LM/LM70.html > > Author: > @@ -29,9 +32,10 @@ available (on page 4) here: > > The hardware interfacing on the LM70 LLP eval board is as follows: > > + ======== == ========= ========== > Parallel LM70 LLP > - Port Direction JP2 Header > - ----------- --------- ---------------- > + Port . Direction JP2 Header > + ======== == ========= ========== > D0 2 - - > D1 3 --> V+ 5 > D2 4 --> V+ 5 > @@ -42,7 +46,7 @@ The hardware interfacing on the LM70 LLP eval board is as follows: > D7 9 --> SI/O 5 > GND 25 - GND 7 > Select 13 <-- SI/O 1 > - ----------- --------- ---------------- > + ======== == ========= ========== > > Note that since the LM70 uses a "3-wire" variant of SPI, the SI/SO pin > is connected to both pin D7 (as Master Out) and Select (as Master In) > @@ -74,6 +78,7 @@ inverting the value read at pin 13. > > Thanks to > --------- > -o David Brownell for mentoring the SPI-side driver development. > -o Dr.Craig Hollabaugh for the (early) "manual" bitbanging driver version. > -o Nadir Billimoria for help interpreting the circuit schematic. > + > +- David Brownell for mentoring the SPI-side driver development. > +- Dr.Craig Hollabaugh for the (early) "manual" bitbanging driver version. > +- Nadir Billimoria for help interpreting the circuit schematic. > diff --git a/Documentation/spi/spi-sc18is602 b/Documentation/spi/spi-sc18is602.rst > similarity index 97% > rename from Documentation/spi/spi-sc18is602 > rename to Documentation/spi/spi-sc18is602.rst > index 0feffd5af411..2a31dc722321 100644 > --- a/Documentation/spi/spi-sc18is602 > +++ b/Documentation/spi/spi-sc18is602.rst > @@ -1,8 +1,11 @@ > +=========================== > Kernel driver spi-sc18is602 > =========================== > > Supported chips: > + > * NXP SI18IS602/602B/603 > + > Datasheet: http://www.nxp.com/documents/data_sheet/SC18IS602_602B_603.pdf > > Author: > diff --git a/Documentation/spi/spi-summary b/Documentation/spi/spi-summary.rst > similarity index 93% > rename from Documentation/spi/spi-summary > rename to Documentation/spi/spi-summary.rst > index 1a63194b74d7..96b3f8b8b3db 100644 > --- a/Documentation/spi/spi-summary > +++ b/Documentation/spi/spi-summary.rst > @@ -1,3 +1,4 @@ > +==================================== > Overview of Linux kernel SPI support > ==================================== > > @@ -139,12 +140,14 @@ a command and then reading its response. > > There are two types of SPI driver, here called: > > - Controller drivers ... controllers may be built into System-On-Chip > + Controller drivers ... > + controllers may be built into System-On-Chip > processors, and often support both Master and Slave roles. > These drivers touch hardware registers and may use DMA. > Or they can be PIO bitbangers, needing just GPIO pins. > > - Protocol drivers ... these pass messages through the controller > + Protocol drivers ... > + these pass messages through the controller > driver to communicate with a Slave or Master device on the > other side of an SPI link. > > @@ -160,7 +163,7 @@ those two types of drivers. > There is a minimal core of SPI programming interfaces, focussing on > using the driver model to connect controller and protocol drivers using > device tables provided by board specific initialization code. SPI > -shows up in sysfs in several locations: > +shows up in sysfs in several locations:: > > /sys/devices/.../CTLR ... physical node for a given SPI controller > > @@ -206,7 +209,8 @@ Linux needs several kinds of information to properly configure SPI devices. > That information is normally provided by board-specific code, even for > chips that do support some of automated discovery/enumeration. > > -DECLARE CONTROLLERS > +Declare Controllers > +^^^^^^^^^^^^^^^^^^^ > > The first kind of information is a list of what SPI controllers exist. > For System-on-Chip (SOC) based boards, these will usually be platform > @@ -221,7 +225,7 @@ same basic controller setup code. This is because most SOCs have several > SPI-capable controllers, and only the ones actually usable on a given > board should normally be set up and registered. > > -So for example arch/.../mach-*/board-*.c files might have code like: > +So for example arch/.../mach-*/board-*.c files might have code like:: > > #include <mach/spi.h> /* for mysoc_spi_data */ > > @@ -238,7 +242,7 @@ So for example arch/.../mach-*/board-*.c files might have code like: > ... > } > > -And SOC-specific utility code might look something like: > +And SOC-specific utility code might look something like:: > > #include <mach/spi.h> > > @@ -269,8 +273,8 @@ same SOC controller is used. For example, on one board SPI might use > an external clock, where another derives the SPI clock from current > settings of some master clock. > > - > -DECLARE SLAVE DEVICES > +Declare Slave Devices > +^^^^^^^^^^^^^^^^^^^^^ > > The second kind of information is a list of what SPI slave devices exist > on the target board, often with some board-specific data needed for the > @@ -278,7 +282,7 @@ driver to work correctly. > > Normally your arch/.../mach-*/board-*.c files would provide a small table > listing the SPI devices on each board. (This would typically be only a > -small handful.) That might look like: > +small handful.) That might look like:: > > static struct ads7846_platform_data ads_info = { > .vref_delay_usecs = 100, > @@ -316,7 +320,7 @@ not possible until the infrastructure knows how to deselect it. > > Then your board initialization code would register that table with the SPI > infrastructure, so that it's available later when the SPI master controller > -driver is registered: > +driver is registered:: > > spi_register_board_info(spi_board_info, ARRAY_SIZE(spi_board_info)); > > @@ -324,12 +328,13 @@ Like with other static board-specific setup, you won't unregister those. > > The widely used "card" style computers bundle memory, cpu, and little else > onto a card that's maybe just thirty square centimeters. On such systems, > -your arch/.../mach-.../board-*.c file would primarily provide information > +your ``arch/.../mach-.../board-*.c`` file would primarily provide information > about the devices on the mainboard into which such a card is plugged. That > certainly includes SPI devices hooked up through the card connectors! > > > -NON-STATIC CONFIGURATIONS > +Non-static Configurations > +^^^^^^^^^^^^^^^^^^^^^^^^^ > > Developer boards often play by different rules than product boards, and one > example is the potential need to hotplug SPI devices and/or controllers. > @@ -349,7 +354,7 @@ How do I write an "SPI Protocol Driver"? > Most SPI drivers are currently kernel drivers, but there's also support > for userspace drivers. Here we talk only about kernel drivers. > > -SPI protocol drivers somewhat resemble platform device drivers: > +SPI protocol drivers somewhat resemble platform device drivers:: > > static struct spi_driver CHIP_driver = { > .driver = { > @@ -367,6 +372,8 @@ device whose board_info gave a modalias of "CHIP". Your probe() code > might look like this unless you're creating a device which is managing > a bus (appearing under /sys/class/spi_master). > > +:: > + > static int CHIP_probe(struct spi_device *spi) > { > struct CHIP *chip; > @@ -479,6 +486,8 @@ The main task of this type of driver is to provide an "spi_master". > Use spi_alloc_master() to allocate the master, and spi_master_get_devdata() > to get the driver-private data allocated for that device. > > +:: > + > struct spi_master *master; > struct CONTROLLER *c; > > @@ -503,7 +512,8 @@ If you need to remove your SPI controller driver, spi_unregister_master() > will reverse the effect of spi_register_master(). > > > -BUS NUMBERING > +Bus Numbering > +^^^^^^^^^^^^^ > > Bus numbering is important, since that's how Linux identifies a given > SPI bus (shared SCK, MOSI, MISO). Valid bus numbers start at zero. On > @@ -517,9 +527,10 @@ then be replaced by a dynamically assigned number. You'd then need to treat > this as a non-static configuration (see above). > > > -SPI MASTER METHODS > +SPI Master Methods > +^^^^^^^^^^^^^^^^^^ > > - master->setup(struct spi_device *spi) > +``master->setup(struct spi_device *spi)`` > This sets up the device clock rate, SPI mode, and word sizes. > Drivers may change the defaults provided by board_info, and then > call spi_setup(spi) to invoke this routine. It may sleep. > @@ -528,37 +539,37 @@ SPI MASTER METHODS > change them right away ... otherwise drivers could corrupt I/O > that's in progress for other SPI devices. > > - ** BUG ALERT: for some reason the first version of > - ** many spi_master drivers seems to get this wrong. > - ** When you code setup(), ASSUME that the controller > - ** is actively processing transfers for another device. > + .. note:: > > - master->cleanup(struct spi_device *spi) > + BUG ALERT: for some reason the first version of > + many spi_master drivers seems to get this wrong. > + When you code setup(), ASSUME that the controller > + is actively processing transfers for another device. > + > +``master->cleanup(struct spi_device *spi)`` > Your controller driver may use spi_device.controller_state to hold > state it dynamically associates with that device. If you do that, > be sure to provide the cleanup() method to free that state. > > - master->prepare_transfer_hardware(struct spi_master *master) > +``master->prepare_transfer_hardware(struct spi_master *master)`` > This will be called by the queue mechanism to signal to the driver > that a message is coming in soon, so the subsystem requests the > driver to prepare the transfer hardware by issuing this call. > This may sleep. > > - master->unprepare_transfer_hardware(struct spi_master *master) > +``master->unprepare_transfer_hardware(struct spi_master *master)`` > This will be called by the queue mechanism to signal to the driver > that there are no more messages pending in the queue and it may > relax the hardware (e.g. by power management calls). This may sleep. > > - master->transfer_one_message(struct spi_master *master, > - struct spi_message *mesg) > +``master->transfer_one_message(struct spi_master *master, struct spi_message *mesg)`` > The subsystem calls the driver to transfer a single message while > queuing transfers that arrive in the meantime. When the driver is > finished with this message, it must call > spi_finalize_current_message() so the subsystem can issue the next > message. This may sleep. > > - master->transfer_one(struct spi_master *master, struct spi_device *spi, > - struct spi_transfer *transfer) > +``master->transfer_one(struct spi_master *master, struct spi_device *spi, struct spi_transfer *transfer)`` > The subsystem calls the driver to transfer a single transfer while > queuing transfers that arrive in the meantime. When the driver is > finished with this transfer, it must call > @@ -568,19 +579,20 @@ SPI MASTER METHODS > not call your transfer_one callback. > > Return values: > - negative errno: error > - 0: transfer is finished > - 1: transfer is still in progress > > - master->set_cs_timing(struct spi_device *spi, u8 setup_clk_cycles, > - u8 hold_clk_cycles, u8 inactive_clk_cycles) > + * negative errno: error > + * 0: transfer is finished > + * 1: transfer is still in progress > + > +``master->set_cs_timing(struct spi_device *spi, u8 setup_clk_cycles, u8 hold_clk_cycles, u8 inactive_clk_cycles)`` > This method allows SPI client drivers to request SPI master controller > for configuring device specific CS setup, hold and inactive timing > requirements. > > - DEPRECATED METHODS > +Deprecated Methods > +^^^^^^^^^^^^^^^^^^ > > - master->transfer(struct spi_device *spi, struct spi_message *message) > +``master->transfer(struct spi_device *spi, struct spi_message *message)`` > This must not sleep. Its responsibility is to arrange that the > transfer happens and its complete() callback is issued. The two > will normally happen later, after other transfers complete, and > @@ -590,7 +602,8 @@ SPI MASTER METHODS > implemented. > > > -SPI MESSAGE QUEUE > +SPI Message Queue > +^^^^^^^^^^^^^^^^^ > > If you are happy with the standard queueing mechanism provided by the > SPI subsystem, just implement the queued methods specified above. Using > @@ -619,13 +632,13 @@ THANKS TO > Contributors to Linux-SPI discussions include (in alphabetical order, > by last name): > > -Mark Brown > -David Brownell > -Russell King > -Grant Likely > -Dmitry Pervushin > -Stephen Street > -Mark Underwood > -Andrew Victor > -Linus Walleij > -Vitaly Wool > +- Mark Brown > +- David Brownell > +- Russell King > +- Grant Likely > +- Dmitry Pervushin > +- Stephen Street > +- Mark Underwood > +- Andrew Victor > +- Linus Walleij > +- Vitaly Wool > diff --git a/Documentation/spi/spidev b/Documentation/spi/spidev.rst > similarity index 90% > rename from Documentation/spi/spidev > rename to Documentation/spi/spidev.rst > index 3d14035b1766..f05dbc5ccdbc 100644 > --- a/Documentation/spi/spidev > +++ b/Documentation/spi/spidev.rst > @@ -1,7 +1,13 @@ > +================= > +SPI userspace API > +================= > + > SPI devices have a limited userspace API, supporting basic half-duplex > read() and write() access to SPI slave devices. Using ioctl() requests, > full duplex transfers and device I/O configuration are also available. > > +:: > + > #include <fcntl.h> > #include <unistd.h> > #include <sys/ioctl.h> > @@ -39,14 +45,17 @@ device node with a "dev" attribute that will be understood by udev or mdev. > busybox; it's less featureful, but often enough.) For a SPI device with > chipselect C on bus B, you should see: > > - /dev/spidevB.C ... character special device, major number 153 with > + /dev/spidevB.C ... > + character special device, major number 153 with > a dynamically chosen minor device number. This is the node > that userspace programs will open, created by "udev" or "mdev". > > - /sys/devices/.../spiB.C ... as usual, the SPI device node will > + /sys/devices/.../spiB.C ... > + as usual, the SPI device node will > be a child of its SPI master controller. > > - /sys/class/spidev/spidevB.C ... created when the "spidev" driver > + /sys/class/spidev/spidevB.C ... > + created when the "spidev" driver > binds to that device. (Directory or symlink, based on whether > or not you enabled the "deprecated sysfs files" Kconfig option.) > > @@ -80,7 +89,8 @@ the SPI_IOC_MESSAGE(N) request. > Several ioctl() requests let your driver read or override the device's current > settings for data transfer parameters: > > - SPI_IOC_RD_MODE, SPI_IOC_WR_MODE ... pass a pointer to a byte which will > + SPI_IOC_RD_MODE, SPI_IOC_WR_MODE ... > + pass a pointer to a byte which will > return (RD) or assign (WR) the SPI transfer mode. Use the constants > SPI_MODE_0..SPI_MODE_3; or if you prefer you can combine SPI_CPOL > (clock polarity, idle high iff this is set) or SPI_CPHA (clock phase, > @@ -88,22 +98,26 @@ settings for data transfer parameters: > Note that this request is limited to SPI mode flags that fit in a > single byte. > > - SPI_IOC_RD_MODE32, SPI_IOC_WR_MODE32 ... pass a pointer to a uin32_t > + SPI_IOC_RD_MODE32, SPI_IOC_WR_MODE32 ... > + pass a pointer to a uin32_t > which will return (RD) or assign (WR) the full SPI transfer mode, > not limited to the bits that fit in one byte. > > - SPI_IOC_RD_LSB_FIRST, SPI_IOC_WR_LSB_FIRST ... pass a pointer to a byte > + SPI_IOC_RD_LSB_FIRST, SPI_IOC_WR_LSB_FIRST ... > + pass a pointer to a byte > which will return (RD) or assign (WR) the bit justification used to > transfer SPI words. Zero indicates MSB-first; other values indicate > the less common LSB-first encoding. In both cases the specified value > is right-justified in each word, so that unused (TX) or undefined (RX) > bits are in the MSBs. > > - SPI_IOC_RD_BITS_PER_WORD, SPI_IOC_WR_BITS_PER_WORD ... pass a pointer to > + SPI_IOC_RD_BITS_PER_WORD, SPI_IOC_WR_BITS_PER_WORD ... > + pass a pointer to > a byte which will return (RD) or assign (WR) the number of bits in > each SPI transfer word. The value zero signifies eight bits. > > - SPI_IOC_RD_MAX_SPEED_HZ, SPI_IOC_WR_MAX_SPEED_HZ ... pass a pointer to a > + SPI_IOC_RD_MAX_SPEED_HZ, SPI_IOC_WR_MAX_SPEED_HZ ... > + pass a pointer to a > u32 which will return (RD) or assign (WR) the maximum SPI transfer > speed, in Hz. The controller can't necessarily assign that specific > clock speed. > diff --git a/drivers/iio/dummy/iio_simple_dummy.c b/drivers/iio/dummy/iio_simple_dummy.c > index d28974ad9e0e..6cb02299a215 100644 > --- a/drivers/iio/dummy/iio_simple_dummy.c > +++ b/drivers/iio/dummy/iio_simple_dummy.c > @@ -695,7 +695,7 @@ static int iio_dummy_remove(struct iio_sw_device *swd) > * i2c: > * Documentation/i2c/writing-clients.rst > * spi: > - * Documentation/spi/spi-summary > + * Documentation/spi/spi-summary.rst > */ > static const struct iio_sw_device_ops iio_dummy_device_ops = { > .probe = iio_dummy_probe, > diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig > index 3a1d8f1170de..d5a24fe983e7 100644 > --- a/drivers/spi/Kconfig > +++ b/drivers/spi/Kconfig > @@ -543,7 +543,7 @@ config SPI_PXA2XX > help > This enables using a PXA2xx or Sodaville SSP port as a SPI master > controller. The driver can be configured to use any SSP port and > - additional documentation can be found a Documentation/spi/pxa2xx. > + additional documentation can be found a Documentation/spi/pxa2xx.rst. > > config SPI_PXA2XX_PCI > def_tristate SPI_PXA2XX && PCI && COMMON_CLK > diff --git a/drivers/spi/spi-butterfly.c b/drivers/spi/spi-butterfly.c > index 8c77d1114ad3..7e71a351f3b7 100644 > --- a/drivers/spi/spi-butterfly.c > +++ b/drivers/spi/spi-butterfly.c > @@ -23,7 +23,7 @@ > * with a battery powered AVR microcontroller and lots of goodies. You > * can use GCC to develop firmware for this. > * > - * See Documentation/spi/butterfly for information about how to build > + * See Documentation/spi/butterfly.rst for information about how to build > * and use this custom parallel port cable. > */ > > diff --git a/drivers/spi/spi-lm70llp.c b/drivers/spi/spi-lm70llp.c > index f18f912c9dea..174dba29b1dd 100644 > --- a/drivers/spi/spi-lm70llp.c > +++ b/drivers/spi/spi-lm70llp.c > @@ -34,7 +34,7 @@ > * available (on page 4) here: > * http://www.national.com/appinfo/tempsensors/files/LM70LLPEVALmanual.pdf > * > - * Also see Documentation/spi/spi-lm70llp. The SPI<->parport code here is > + * Also see Documentation/spi/spi-lm70llp.rst. The SPI<->parport code here is > * (heavily) based on spi-butterfly by David Brownell. > * > * The LM70 LLP connects to the PC parallel port in the following manner: > diff --git a/include/linux/platform_data/sc18is602.h b/include/linux/platform_data/sc18is602.h > index e066d3b0d6d8..0e91489edfe6 100644 > --- a/include/linux/platform_data/sc18is602.h > +++ b/include/linux/platform_data/sc18is602.h > @@ -4,7 +4,7 @@ > * > * Copyright (C) 2012 Guenter Roeck <linux@roeck-us.net> > * > - * For further information, see the Documentation/spi/spi-sc18is602 file. > + * For further information, see the Documentation/spi/spi-sc18is602.rst file. > */ > > /**
diff --git a/Documentation/index.rst b/Documentation/index.rst index 38ece18f5d1e..bcaddbfa817f 100644 --- a/Documentation/index.rst +++ b/Documentation/index.rst @@ -115,6 +115,7 @@ needed). power/index target/index timers/index + spi/index w1/index watchdog/index input/index diff --git a/Documentation/spi/butterfly b/Documentation/spi/butterfly.rst similarity index 71% rename from Documentation/spi/butterfly rename to Documentation/spi/butterfly.rst index 9927af7a629c..e614a589547c 100644 --- a/Documentation/spi/butterfly +++ b/Documentation/spi/butterfly.rst @@ -1,3 +1,4 @@ +=================================================== spi_butterfly - parport-to-butterfly adapter driver =================================================== @@ -27,25 +28,29 @@ need to reflash the firmware, and the pins are the standard Atmel "ISP" connector pins (used also on non-Butterfly AVR boards). On the parport side this is like "sp12" programming cables. + ====== ============= =================== Signal Butterfly Parport (DB-25) - ------ --------- --------------- - SCK = J403.PB1/SCK = pin 2/D0 - RESET = J403.nRST = pin 3/D1 - VCC = J403.VCC_EXT = pin 8/D6 - MOSI = J403.PB2/MOSI = pin 9/D7 - MISO = J403.PB3/MISO = pin 11/S7,nBUSY - GND = J403.GND = pin 23/GND + ====== ============= =================== + SCK J403.PB1/SCK pin 2/D0 + RESET J403.nRST pin 3/D1 + VCC J403.VCC_EXT pin 8/D6 + MOSI J403.PB2/MOSI pin 9/D7 + MISO J403.PB3/MISO pin 11/S7,nBUSY + GND J403.GND pin 23/GND + ====== ============= =================== Then to let Linux master that bus to talk to the DataFlash chip, you must (a) flash new firmware that disables SPI (set PRR.2, and disable pullups by clearing PORTB.[0-3]); (b) configure the mtd_dataflash driver; and (c) cable in the chipselect. + ====== ============ =================== Signal Butterfly Parport (DB-25) - ------ --------- --------------- - VCC = J400.VCC_EXT = pin 7/D5 - SELECT = J400.PB0/nSS = pin 17/C3,nSELECT - GND = J400.GND = pin 24/GND + ====== ============ =================== + VCC J400.VCC_EXT pin 7/D5 + SELECT J400.PB0/nSS pin 17/C3,nSELECT + GND J400.GND pin 24/GND + ====== ============ =================== Or you could flash firmware making the AVR into an SPI slave (keeping the DataFlash in reset) and tweak the spi_butterfly driver to make it bind to @@ -56,13 +61,14 @@ That would let you talk to the AVR using custom SPI-with-USI firmware, while letting either Linux or the AVR use the DataFlash. There are plenty of spare parport pins to wire this one up, such as: + ====== ============= =================== Signal Butterfly Parport (DB-25) - ------ --------- --------------- - SCK = J403.PE4/USCK = pin 5/D3 - MOSI = J403.PE5/DI = pin 6/D4 - MISO = J403.PE6/DO = pin 12/S5,nPAPEROUT - GND = J403.GND = pin 22/GND - - IRQ = J402.PF4 = pin 10/S6,ACK - GND = J402.GND(P2) = pin 25/GND + ====== ============= =================== + SCK J403.PE4/USCK pin 5/D3 + MOSI J403.PE5/DI pin 6/D4 + MISO J403.PE6/DO pin 12/S5,nPAPEROUT + GND J403.GND pin 22/GND + IRQ J402.PF4 pin 10/S6,ACK + GND J402.GND(P2) pin 25/GND + ====== ============= =================== diff --git a/Documentation/spi/index.rst b/Documentation/spi/index.rst new file mode 100644 index 000000000000..bad6259a7bb6 --- /dev/null +++ b/Documentation/spi/index.rst @@ -0,0 +1,23 @@ +.. SPDX-License-Identifier: GPL-2.0 + +================================= +Serial Peripheral Interface (SPI) +================================= + +.. toctree:: + :maxdepth: 1 + + spi-summary + spidev + butterfly + pxa2xx + spi-lm70llp + spi-sc18is602 + +.. only:: subproject and html + + Indices + ======= + + * :ref:`genindex` + diff --git a/Documentation/spi/pxa2xx b/Documentation/spi/pxa2xx.rst similarity index 83% rename from Documentation/spi/pxa2xx rename to Documentation/spi/pxa2xx.rst index 551325b66b23..457faef8be74 100644 --- a/Documentation/spi/pxa2xx +++ b/Documentation/spi/pxa2xx.rst @@ -1,8 +1,10 @@ +============================== PXA2xx SPI on SSP driver HOWTO -=================================================== +============================== + This a mini howto on the pxa2xx_spi driver. The driver turns a PXA2xx synchronous serial port into a SPI master controller -(see Documentation/spi/spi-summary). The driver has the following features +(see Documentation/spi/spi-summary.rst). The driver has the following features - Support for any PXA2xx SSP - SSP PIO and SSP DMA data transfers. @@ -19,12 +21,12 @@ Declaring PXA2xx Master Controllers ----------------------------------- Typically a SPI master is defined in the arch/.../mach-*/board-*.c as a "platform device". The master configuration is passed to the driver via a table -found in include/linux/spi/pxa2xx_spi.h: +found in include/linux/spi/pxa2xx_spi.h:: -struct pxa2xx_spi_controller { + struct pxa2xx_spi_controller { u16 num_chipselect; u8 enable_dma; -}; + }; The "pxa2xx_spi_controller.num_chipselect" field is used to determine the number of slave device (chips) attached to this SPI master. @@ -36,9 +38,9 @@ See the "PXA2xx Developer Manual" section "DMA Controller". NSSP MASTER SAMPLE ------------------ -Below is a sample configuration using the PXA255 NSSP. +Below is a sample configuration using the PXA255 NSSP:: -static struct resource pxa_spi_nssp_resources[] = { + static struct resource pxa_spi_nssp_resources[] = { [0] = { .start = __PREG(SSCR0_P(2)), /* Start address of NSSP */ .end = __PREG(SSCR0_P(2)) + 0x2c, /* Range of registers */ @@ -49,14 +51,14 @@ static struct resource pxa_spi_nssp_resources[] = { .end = IRQ_NSSP, .flags = IORESOURCE_IRQ, }, -}; + }; -static struct pxa2xx_spi_controller pxa_nssp_master_info = { + static struct pxa2xx_spi_controller pxa_nssp_master_info = { .num_chipselect = 1, /* Matches the number of chips attached to NSSP */ .enable_dma = 1, /* Enables NSSP DMA */ -}; + }; -static struct platform_device pxa_spi_nssp = { + static struct platform_device pxa_spi_nssp = { .name = "pxa2xx-spi", /* MUST BE THIS VALUE, so device match driver */ .id = 2, /* Bus number, MUST MATCH SSP number 1..n */ .resource = pxa_spi_nssp_resources, @@ -64,22 +66,22 @@ static struct platform_device pxa_spi_nssp = { .dev = { .platform_data = &pxa_nssp_master_info, /* Passed to driver */ }, -}; + }; -static struct platform_device *devices[] __initdata = { + static struct platform_device *devices[] __initdata = { &pxa_spi_nssp, -}; + }; -static void __init board_init(void) -{ + static void __init board_init(void) + { (void)platform_add_device(devices, ARRAY_SIZE(devices)); -} + } Declaring Slave Devices ----------------------- Typically each SPI slave (chip) is defined in the arch/.../mach-*/board-*.c using the "spi_board_info" structure found in "linux/spi/spi.h". See -"Documentation/spi/spi-summary" for additional information. +"Documentation/spi/spi-summary.rst" for additional information. Each slave device attached to the PXA must provide slave specific configuration information via the structure "pxa2xx_spi_chip" found in @@ -87,19 +89,21 @@ information via the structure "pxa2xx_spi_chip" found in will uses the configuration whenever the driver communicates with the slave device. All fields are optional. -struct pxa2xx_spi_chip { +:: + + struct pxa2xx_spi_chip { u8 tx_threshold; u8 rx_threshold; u8 dma_burst_size; u32 timeout; u8 enable_loopback; void (*cs_control)(u32 command); -}; + }; The "pxa2xx_spi_chip.tx_threshold" and "pxa2xx_spi_chip.rx_threshold" fields are used to configure the SSP hardware fifo. These fields are critical to the performance of pxa2xx_spi driver and misconfiguration will result in rx -fifo overruns (especially in PIO mode transfers). Good default values are +fifo overruns (especially in PIO mode transfers). Good default values are:: .tx_threshold = 8, .rx_threshold = 8, @@ -141,41 +145,43 @@ The pxa2xx_spi_chip structure is passed to the pxa2xx_spi driver in the "spi_board_info.controller_data" field. Below is a sample configuration using the PXA255 NSSP. -/* Chip Select control for the CS8415A SPI slave device */ -static void cs8415a_cs_control(u32 command) -{ +:: + + /* Chip Select control for the CS8415A SPI slave device */ + static void cs8415a_cs_control(u32 command) + { if (command & PXA2XX_CS_ASSERT) GPCR(2) = GPIO_bit(2); else GPSR(2) = GPIO_bit(2); -} + } -/* Chip Select control for the CS8405A SPI slave device */ -static void cs8405a_cs_control(u32 command) -{ + /* Chip Select control for the CS8405A SPI slave device */ + static void cs8405a_cs_control(u32 command) + { if (command & PXA2XX_CS_ASSERT) GPCR(3) = GPIO_bit(3); else GPSR(3) = GPIO_bit(3); -} + } -static struct pxa2xx_spi_chip cs8415a_chip_info = { + static struct pxa2xx_spi_chip cs8415a_chip_info = { .tx_threshold = 8, /* SSP hardward FIFO threshold */ .rx_threshold = 8, /* SSP hardward FIFO threshold */ .dma_burst_size = 8, /* Byte wide transfers used so 8 byte bursts */ .timeout = 235, /* See Intel documentation */ .cs_control = cs8415a_cs_control, /* Use external chip select */ -}; + }; -static struct pxa2xx_spi_chip cs8405a_chip_info = { + static struct pxa2xx_spi_chip cs8405a_chip_info = { .tx_threshold = 8, /* SSP hardward FIFO threshold */ .rx_threshold = 8, /* SSP hardward FIFO threshold */ .dma_burst_size = 8, /* Byte wide transfers used so 8 byte bursts */ .timeout = 235, /* See Intel documentation */ .cs_control = cs8405a_cs_control, /* Use external chip select */ -}; + }; -static struct spi_board_info streetracer_spi_board_info[] __initdata = { + static struct spi_board_info streetracer_spi_board_info[] __initdata = { { .modalias = "cs8415a", /* Name of spi_driver for this device */ .max_speed_hz = 3686400, /* Run SSP as fast a possbile */ @@ -193,13 +199,13 @@ static struct spi_board_info streetracer_spi_board_info[] __initdata = { .controller_data = &cs8405a_chip_info, /* Master chip config */ .irq = STREETRACER_APCI_IRQ, /* Slave device interrupt */ }, -}; + }; -static void __init streetracer_init(void) -{ + static void __init streetracer_init(void) + { spi_register_board_info(streetracer_spi_board_info, ARRAY_SIZE(streetracer_spi_board_info)); -} + } DMA and PIO I/O Support @@ -210,22 +216,22 @@ by setting the "enable_dma" flag in the "pxa2xx_spi_controller" structure. The mode supports both coherent and stream based DMA mappings. The following logic is used to determine the type of I/O to be used on -a per "spi_transfer" basis: +a per "spi_transfer" basis:: -if !enable_dma then + if !enable_dma then always use PIO transfers -if spi_message.len > 8191 then + if spi_message.len > 8191 then print "rate limited" warning use PIO transfers -if spi_message.is_dma_mapped and rx_dma_buf != 0 and tx_dma_buf != 0 then + if spi_message.is_dma_mapped and rx_dma_buf != 0 and tx_dma_buf != 0 then use coherent DMA mode -if rx_buf and tx_buf are aligned on 8 byte boundary then + if rx_buf and tx_buf are aligned on 8 byte boundary then use streaming DMA mode -otherwise + otherwise use PIO transfer THANKS TO diff --git a/Documentation/spi/spi-lm70llp b/Documentation/spi/spi-lm70llp.rst similarity index 88% rename from Documentation/spi/spi-lm70llp rename to Documentation/spi/spi-lm70llp.rst index 463f6d01fa15..07631aef4343 100644 --- a/Documentation/spi/spi-lm70llp +++ b/Documentation/spi/spi-lm70llp.rst @@ -1,8 +1,11 @@ +============================================== spi_lm70llp : LM70-LLP parport-to-SPI adapter ============================================== Supported board/chip: + * National Semiconductor LM70 LLP evaluation board + Datasheet: http://www.national.com/pf/LM/LM70.html Author: @@ -29,9 +32,10 @@ available (on page 4) here: The hardware interfacing on the LM70 LLP eval board is as follows: + ======== == ========= ========== Parallel LM70 LLP - Port Direction JP2 Header - ----------- --------- ---------------- + Port . Direction JP2 Header + ======== == ========= ========== D0 2 - - D1 3 --> V+ 5 D2 4 --> V+ 5 @@ -42,7 +46,7 @@ The hardware interfacing on the LM70 LLP eval board is as follows: D7 9 --> SI/O 5 GND 25 - GND 7 Select 13 <-- SI/O 1 - ----------- --------- ---------------- + ======== == ========= ========== Note that since the LM70 uses a "3-wire" variant of SPI, the SI/SO pin is connected to both pin D7 (as Master Out) and Select (as Master In) @@ -74,6 +78,7 @@ inverting the value read at pin 13. Thanks to --------- -o David Brownell for mentoring the SPI-side driver development. -o Dr.Craig Hollabaugh for the (early) "manual" bitbanging driver version. -o Nadir Billimoria for help interpreting the circuit schematic. + +- David Brownell for mentoring the SPI-side driver development. +- Dr.Craig Hollabaugh for the (early) "manual" bitbanging driver version. +- Nadir Billimoria for help interpreting the circuit schematic. diff --git a/Documentation/spi/spi-sc18is602 b/Documentation/spi/spi-sc18is602.rst similarity index 97% rename from Documentation/spi/spi-sc18is602 rename to Documentation/spi/spi-sc18is602.rst index 0feffd5af411..2a31dc722321 100644 --- a/Documentation/spi/spi-sc18is602 +++ b/Documentation/spi/spi-sc18is602.rst @@ -1,8 +1,11 @@ +=========================== Kernel driver spi-sc18is602 =========================== Supported chips: + * NXP SI18IS602/602B/603 + Datasheet: http://www.nxp.com/documents/data_sheet/SC18IS602_602B_603.pdf Author: diff --git a/Documentation/spi/spi-summary b/Documentation/spi/spi-summary.rst similarity index 93% rename from Documentation/spi/spi-summary rename to Documentation/spi/spi-summary.rst index 1a63194b74d7..96b3f8b8b3db 100644 --- a/Documentation/spi/spi-summary +++ b/Documentation/spi/spi-summary.rst @@ -1,3 +1,4 @@ +==================================== Overview of Linux kernel SPI support ==================================== @@ -139,12 +140,14 @@ a command and then reading its response. There are two types of SPI driver, here called: - Controller drivers ... controllers may be built into System-On-Chip + Controller drivers ... + controllers may be built into System-On-Chip processors, and often support both Master and Slave roles. These drivers touch hardware registers and may use DMA. Or they can be PIO bitbangers, needing just GPIO pins. - Protocol drivers ... these pass messages through the controller + Protocol drivers ... + these pass messages through the controller driver to communicate with a Slave or Master device on the other side of an SPI link. @@ -160,7 +163,7 @@ those two types of drivers. There is a minimal core of SPI programming interfaces, focussing on using the driver model to connect controller and protocol drivers using device tables provided by board specific initialization code. SPI -shows up in sysfs in several locations: +shows up in sysfs in several locations:: /sys/devices/.../CTLR ... physical node for a given SPI controller @@ -206,7 +209,8 @@ Linux needs several kinds of information to properly configure SPI devices. That information is normally provided by board-specific code, even for chips that do support some of automated discovery/enumeration. -DECLARE CONTROLLERS +Declare Controllers +^^^^^^^^^^^^^^^^^^^ The first kind of information is a list of what SPI controllers exist. For System-on-Chip (SOC) based boards, these will usually be platform @@ -221,7 +225,7 @@ same basic controller setup code. This is because most SOCs have several SPI-capable controllers, and only the ones actually usable on a given board should normally be set up and registered. -So for example arch/.../mach-*/board-*.c files might have code like: +So for example arch/.../mach-*/board-*.c files might have code like:: #include <mach/spi.h> /* for mysoc_spi_data */ @@ -238,7 +242,7 @@ So for example arch/.../mach-*/board-*.c files might have code like: ... } -And SOC-specific utility code might look something like: +And SOC-specific utility code might look something like:: #include <mach/spi.h> @@ -269,8 +273,8 @@ same SOC controller is used. For example, on one board SPI might use an external clock, where another derives the SPI clock from current settings of some master clock. - -DECLARE SLAVE DEVICES +Declare Slave Devices +^^^^^^^^^^^^^^^^^^^^^ The second kind of information is a list of what SPI slave devices exist on the target board, often with some board-specific data needed for the @@ -278,7 +282,7 @@ driver to work correctly. Normally your arch/.../mach-*/board-*.c files would provide a small table listing the SPI devices on each board. (This would typically be only a -small handful.) That might look like: +small handful.) That might look like:: static struct ads7846_platform_data ads_info = { .vref_delay_usecs = 100, @@ -316,7 +320,7 @@ not possible until the infrastructure knows how to deselect it. Then your board initialization code would register that table with the SPI infrastructure, so that it's available later when the SPI master controller -driver is registered: +driver is registered:: spi_register_board_info(spi_board_info, ARRAY_SIZE(spi_board_info)); @@ -324,12 +328,13 @@ Like with other static board-specific setup, you won't unregister those. The widely used "card" style computers bundle memory, cpu, and little else onto a card that's maybe just thirty square centimeters. On such systems, -your arch/.../mach-.../board-*.c file would primarily provide information +your ``arch/.../mach-.../board-*.c`` file would primarily provide information about the devices on the mainboard into which such a card is plugged. That certainly includes SPI devices hooked up through the card connectors! -NON-STATIC CONFIGURATIONS +Non-static Configurations +^^^^^^^^^^^^^^^^^^^^^^^^^ Developer boards often play by different rules than product boards, and one example is the potential need to hotplug SPI devices and/or controllers. @@ -349,7 +354,7 @@ How do I write an "SPI Protocol Driver"? Most SPI drivers are currently kernel drivers, but there's also support for userspace drivers. Here we talk only about kernel drivers. -SPI protocol drivers somewhat resemble platform device drivers: +SPI protocol drivers somewhat resemble platform device drivers:: static struct spi_driver CHIP_driver = { .driver = { @@ -367,6 +372,8 @@ device whose board_info gave a modalias of "CHIP". Your probe() code might look like this unless you're creating a device which is managing a bus (appearing under /sys/class/spi_master). +:: + static int CHIP_probe(struct spi_device *spi) { struct CHIP *chip; @@ -479,6 +486,8 @@ The main task of this type of driver is to provide an "spi_master". Use spi_alloc_master() to allocate the master, and spi_master_get_devdata() to get the driver-private data allocated for that device. +:: + struct spi_master *master; struct CONTROLLER *c; @@ -503,7 +512,8 @@ If you need to remove your SPI controller driver, spi_unregister_master() will reverse the effect of spi_register_master(). -BUS NUMBERING +Bus Numbering +^^^^^^^^^^^^^ Bus numbering is important, since that's how Linux identifies a given SPI bus (shared SCK, MOSI, MISO). Valid bus numbers start at zero. On @@ -517,9 +527,10 @@ then be replaced by a dynamically assigned number. You'd then need to treat this as a non-static configuration (see above). -SPI MASTER METHODS +SPI Master Methods +^^^^^^^^^^^^^^^^^^ - master->setup(struct spi_device *spi) +``master->setup(struct spi_device *spi)`` This sets up the device clock rate, SPI mode, and word sizes. Drivers may change the defaults provided by board_info, and then call spi_setup(spi) to invoke this routine. It may sleep. @@ -528,37 +539,37 @@ SPI MASTER METHODS change them right away ... otherwise drivers could corrupt I/O that's in progress for other SPI devices. - ** BUG ALERT: for some reason the first version of - ** many spi_master drivers seems to get this wrong. - ** When you code setup(), ASSUME that the controller - ** is actively processing transfers for another device. + .. note:: - master->cleanup(struct spi_device *spi) + BUG ALERT: for some reason the first version of + many spi_master drivers seems to get this wrong. + When you code setup(), ASSUME that the controller + is actively processing transfers for another device. + +``master->cleanup(struct spi_device *spi)`` Your controller driver may use spi_device.controller_state to hold state it dynamically associates with that device. If you do that, be sure to provide the cleanup() method to free that state. - master->prepare_transfer_hardware(struct spi_master *master) +``master->prepare_transfer_hardware(struct spi_master *master)`` This will be called by the queue mechanism to signal to the driver that a message is coming in soon, so the subsystem requests the driver to prepare the transfer hardware by issuing this call. This may sleep. - master->unprepare_transfer_hardware(struct spi_master *master) +``master->unprepare_transfer_hardware(struct spi_master *master)`` This will be called by the queue mechanism to signal to the driver that there are no more messages pending in the queue and it may relax the hardware (e.g. by power management calls). This may sleep. - master->transfer_one_message(struct spi_master *master, - struct spi_message *mesg) +``master->transfer_one_message(struct spi_master *master, struct spi_message *mesg)`` The subsystem calls the driver to transfer a single message while queuing transfers that arrive in the meantime. When the driver is finished with this message, it must call spi_finalize_current_message() so the subsystem can issue the next message. This may sleep. - master->transfer_one(struct spi_master *master, struct spi_device *spi, - struct spi_transfer *transfer) +``master->transfer_one(struct spi_master *master, struct spi_device *spi, struct spi_transfer *transfer)`` The subsystem calls the driver to transfer a single transfer while queuing transfers that arrive in the meantime. When the driver is finished with this transfer, it must call @@ -568,19 +579,20 @@ SPI MASTER METHODS not call your transfer_one callback. Return values: - negative errno: error - 0: transfer is finished - 1: transfer is still in progress - master->set_cs_timing(struct spi_device *spi, u8 setup_clk_cycles, - u8 hold_clk_cycles, u8 inactive_clk_cycles) + * negative errno: error + * 0: transfer is finished + * 1: transfer is still in progress + +``master->set_cs_timing(struct spi_device *spi, u8 setup_clk_cycles, u8 hold_clk_cycles, u8 inactive_clk_cycles)`` This method allows SPI client drivers to request SPI master controller for configuring device specific CS setup, hold and inactive timing requirements. - DEPRECATED METHODS +Deprecated Methods +^^^^^^^^^^^^^^^^^^ - master->transfer(struct spi_device *spi, struct spi_message *message) +``master->transfer(struct spi_device *spi, struct spi_message *message)`` This must not sleep. Its responsibility is to arrange that the transfer happens and its complete() callback is issued. The two will normally happen later, after other transfers complete, and @@ -590,7 +602,8 @@ SPI MASTER METHODS implemented. -SPI MESSAGE QUEUE +SPI Message Queue +^^^^^^^^^^^^^^^^^ If you are happy with the standard queueing mechanism provided by the SPI subsystem, just implement the queued methods specified above. Using @@ -619,13 +632,13 @@ THANKS TO Contributors to Linux-SPI discussions include (in alphabetical order, by last name): -Mark Brown -David Brownell -Russell King -Grant Likely -Dmitry Pervushin -Stephen Street -Mark Underwood -Andrew Victor -Linus Walleij -Vitaly Wool +- Mark Brown +- David Brownell +- Russell King +- Grant Likely +- Dmitry Pervushin +- Stephen Street +- Mark Underwood +- Andrew Victor +- Linus Walleij +- Vitaly Wool diff --git a/Documentation/spi/spidev b/Documentation/spi/spidev.rst similarity index 90% rename from Documentation/spi/spidev rename to Documentation/spi/spidev.rst index 3d14035b1766..f05dbc5ccdbc 100644 --- a/Documentation/spi/spidev +++ b/Documentation/spi/spidev.rst @@ -1,7 +1,13 @@ +================= +SPI userspace API +================= + SPI devices have a limited userspace API, supporting basic half-duplex read() and write() access to SPI slave devices. Using ioctl() requests, full duplex transfers and device I/O configuration are also available. +:: + #include <fcntl.h> #include <unistd.h> #include <sys/ioctl.h> @@ -39,14 +45,17 @@ device node with a "dev" attribute that will be understood by udev or mdev. busybox; it's less featureful, but often enough.) For a SPI device with chipselect C on bus B, you should see: - /dev/spidevB.C ... character special device, major number 153 with + /dev/spidevB.C ... + character special device, major number 153 with a dynamically chosen minor device number. This is the node that userspace programs will open, created by "udev" or "mdev". - /sys/devices/.../spiB.C ... as usual, the SPI device node will + /sys/devices/.../spiB.C ... + as usual, the SPI device node will be a child of its SPI master controller. - /sys/class/spidev/spidevB.C ... created when the "spidev" driver + /sys/class/spidev/spidevB.C ... + created when the "spidev" driver binds to that device. (Directory or symlink, based on whether or not you enabled the "deprecated sysfs files" Kconfig option.) @@ -80,7 +89,8 @@ the SPI_IOC_MESSAGE(N) request. Several ioctl() requests let your driver read or override the device's current settings for data transfer parameters: - SPI_IOC_RD_MODE, SPI_IOC_WR_MODE ... pass a pointer to a byte which will + SPI_IOC_RD_MODE, SPI_IOC_WR_MODE ... + pass a pointer to a byte which will return (RD) or assign (WR) the SPI transfer mode. Use the constants SPI_MODE_0..SPI_MODE_3; or if you prefer you can combine SPI_CPOL (clock polarity, idle high iff this is set) or SPI_CPHA (clock phase, @@ -88,22 +98,26 @@ settings for data transfer parameters: Note that this request is limited to SPI mode flags that fit in a single byte. - SPI_IOC_RD_MODE32, SPI_IOC_WR_MODE32 ... pass a pointer to a uin32_t + SPI_IOC_RD_MODE32, SPI_IOC_WR_MODE32 ... + pass a pointer to a uin32_t which will return (RD) or assign (WR) the full SPI transfer mode, not limited to the bits that fit in one byte. - SPI_IOC_RD_LSB_FIRST, SPI_IOC_WR_LSB_FIRST ... pass a pointer to a byte + SPI_IOC_RD_LSB_FIRST, SPI_IOC_WR_LSB_FIRST ... + pass a pointer to a byte which will return (RD) or assign (WR) the bit justification used to transfer SPI words. Zero indicates MSB-first; other values indicate the less common LSB-first encoding. In both cases the specified value is right-justified in each word, so that unused (TX) or undefined (RX) bits are in the MSBs. - SPI_IOC_RD_BITS_PER_WORD, SPI_IOC_WR_BITS_PER_WORD ... pass a pointer to + SPI_IOC_RD_BITS_PER_WORD, SPI_IOC_WR_BITS_PER_WORD ... + pass a pointer to a byte which will return (RD) or assign (WR) the number of bits in each SPI transfer word. The value zero signifies eight bits. - SPI_IOC_RD_MAX_SPEED_HZ, SPI_IOC_WR_MAX_SPEED_HZ ... pass a pointer to a + SPI_IOC_RD_MAX_SPEED_HZ, SPI_IOC_WR_MAX_SPEED_HZ ... + pass a pointer to a u32 which will return (RD) or assign (WR) the maximum SPI transfer speed, in Hz. The controller can't necessarily assign that specific clock speed. diff --git a/drivers/iio/dummy/iio_simple_dummy.c b/drivers/iio/dummy/iio_simple_dummy.c index d28974ad9e0e..6cb02299a215 100644 --- a/drivers/iio/dummy/iio_simple_dummy.c +++ b/drivers/iio/dummy/iio_simple_dummy.c @@ -695,7 +695,7 @@ static int iio_dummy_remove(struct iio_sw_device *swd) * i2c: * Documentation/i2c/writing-clients.rst * spi: - * Documentation/spi/spi-summary + * Documentation/spi/spi-summary.rst */ static const struct iio_sw_device_ops iio_dummy_device_ops = { .probe = iio_dummy_probe, diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig index 3a1d8f1170de..d5a24fe983e7 100644 --- a/drivers/spi/Kconfig +++ b/drivers/spi/Kconfig @@ -543,7 +543,7 @@ config SPI_PXA2XX help This enables using a PXA2xx or Sodaville SSP port as a SPI master controller. The driver can be configured to use any SSP port and - additional documentation can be found a Documentation/spi/pxa2xx. + additional documentation can be found a Documentation/spi/pxa2xx.rst. config SPI_PXA2XX_PCI def_tristate SPI_PXA2XX && PCI && COMMON_CLK diff --git a/drivers/spi/spi-butterfly.c b/drivers/spi/spi-butterfly.c index 8c77d1114ad3..7e71a351f3b7 100644 --- a/drivers/spi/spi-butterfly.c +++ b/drivers/spi/spi-butterfly.c @@ -23,7 +23,7 @@ * with a battery powered AVR microcontroller and lots of goodies. You * can use GCC to develop firmware for this. * - * See Documentation/spi/butterfly for information about how to build + * See Documentation/spi/butterfly.rst for information about how to build * and use this custom parallel port cable. */ diff --git a/drivers/spi/spi-lm70llp.c b/drivers/spi/spi-lm70llp.c index f18f912c9dea..174dba29b1dd 100644 --- a/drivers/spi/spi-lm70llp.c +++ b/drivers/spi/spi-lm70llp.c @@ -34,7 +34,7 @@ * available (on page 4) here: * http://www.national.com/appinfo/tempsensors/files/LM70LLPEVALmanual.pdf * - * Also see Documentation/spi/spi-lm70llp. The SPI<->parport code here is + * Also see Documentation/spi/spi-lm70llp.rst. The SPI<->parport code here is * (heavily) based on spi-butterfly by David Brownell. * * The LM70 LLP connects to the PC parallel port in the following manner: diff --git a/include/linux/platform_data/sc18is602.h b/include/linux/platform_data/sc18is602.h index e066d3b0d6d8..0e91489edfe6 100644 --- a/include/linux/platform_data/sc18is602.h +++ b/include/linux/platform_data/sc18is602.h @@ -4,7 +4,7 @@ * * Copyright (C) 2012 Guenter Roeck <linux@roeck-us.net> * - * For further information, see the Documentation/spi/spi-sc18is602 file. + * For further information, see the Documentation/spi/spi-sc18is602.rst file. */ /**
While there's one file there with briefily describes the uAPI, the documentation was written just like most subsystems: focused on kernel developers. So, add it together with driver-api books. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> --- Documentation/index.rst | 1 + .../spi/{butterfly => butterfly.rst} | 44 ++++---- Documentation/spi/index.rst | 23 ++++ Documentation/spi/{pxa2xx => pxa2xx.rst} | 94 ++++++++-------- .../spi/{spi-lm70llp => spi-lm70llp.rst} | 17 ++- .../spi/{spi-sc18is602 => spi-sc18is602.rst} | 3 + .../spi/{spi-summary => spi-summary.rst} | 103 ++++++++++-------- Documentation/spi/{spidev => spidev.rst} | 30 +++-- drivers/iio/dummy/iio_simple_dummy.c | 2 +- drivers/spi/Kconfig | 2 +- drivers/spi/spi-butterfly.c | 2 +- drivers/spi/spi-lm70llp.c | 2 +- include/linux/platform_data/sc18is602.h | 2 +- 13 files changed, 198 insertions(+), 127 deletions(-) rename Documentation/spi/{butterfly => butterfly.rst} (71%) create mode 100644 Documentation/spi/index.rst rename Documentation/spi/{pxa2xx => pxa2xx.rst} (83%) rename Documentation/spi/{spi-lm70llp => spi-lm70llp.rst} (88%) rename Documentation/spi/{spi-sc18is602 => spi-sc18is602.rst} (97%) rename Documentation/spi/{spi-summary => spi-summary.rst} (93%) rename Documentation/spi/{spidev => spidev.rst} (90%)