[2/3] spi: add initial set of spi_transfer transformation methods

Message ID	1448888695-2260-3-git-send-email-kernel@martin.sperl.org (mailing list archive)
State	New, archived
Headers	show Return-Path: <linux-spi-owner@kernel.org> From: kernel@martin.sperl.org To: Mark Brown <broonie@kernel.org>, Stephen Warren <swarren@wwwdotorg.org>, Lee Jones <lee@kernel.org>, Eric Anholt <eric@anholt.net>, linux-spi@vger.kernel.org, linux-rpi-kernel@lists.infradead.org Cc: Martin Sperl <kernel@martin.sperl.org> Subject: [PATCH 2/3] spi: add initial set of spi_transfer transformation methods Date: Mon, 30 Nov 2015 13:04:53 +0000 Message-Id: <1448888695-2260-3-git-send-email-kernel@martin.sperl.org> In-Reply-To: <1448888695-2260-1-git-send-email-kernel@martin.sperl.org> References: <1448888695-2260-1-git-send-email-kernel@martin.sperl.org> Sender: linux-spi-owner@vger.kernel.org Precedence: bulk

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index eecbbe1..7576131 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -145,6 +145,9 @@ SPI_STATISTICS_TRANSFER_BYTES_HISTO(14, "16384-32767"); SPI_STATISTICS_TRANSFER_BYTES_HISTO(15, "32768-65535"); SPI_STATISTICS_TRANSFER_BYTES_HISTO(16, "65536+"); +SPI_STATISTICS_SHOW(transfers_split_maxsize, "%lu"); +SPI_STATISTICS_SHOW(transfers_split_unaligned, "%lu"); + static struct attribute *spi_dev_attrs[] = { &dev_attr_modalias.attr, NULL, @@ -182,6 +185,8 @@ static struct attribute *spi_device_statistics_attrs[] = { &dev_attr_spi_device_transfer_bytes_histo14.attr, &dev_attr_spi_device_transfer_bytes_histo15.attr, &dev_attr_spi_device_transfer_bytes_histo16.attr, + &dev_attr_spi_device_transfers_split_maxsize.attr, + &dev_attr_spi_device_transfers_split_unaligned.attr, NULL, }; @@ -224,6 +229,8 @@ static struct attribute *spi_master_statistics_attrs[] = { &dev_attr_spi_master_transfer_bytes_histo14.attr, &dev_attr_spi_master_transfer_bytes_histo15.attr, &dev_attr_spi_master_transfer_bytes_histo16.attr, + &dev_attr_spi_master_transfers_split_maxsize.attr, + &dev_attr_spi_master_transfers_split_unaligned.attr, NULL, }; @@ -2103,6 +2110,391 @@ void spi_res_release(struct spi_master *master, } } EXPORT_SYMBOL_GPL(spi_res_release); +/*-------------------------------------------------------------------------*/ + +/* Core methods for spi_message alterations */ + +/* the spi_resource structure used */ +struct spi_res_replaced_transfers { + spi_res_release_t release; + struct list_head replaced_transfers; + int inserted; + struct spi_transfer xfers[]; +}; + +static void __spi_replace_transfers_release(struct spi_master *master, + struct spi_message *msg, + void *res) +{ + struct spi_res_replaced_transfers *srt = res; + int i; + + /* call extra callback */ + if (srt->release) + srt->release(master, msg, res); + + /* insert transfers back into the message ahead of xfers[0] */ + list_splice(&srt->replaced_transfers, &srt->xfers[0].transfer_list); + + /* remove the formerly inserted entries */ + for (i = 0; i < srt->inserted; i++) + list_del(&srt->xfers[i].transfer_list); +} + +/** + * spi_replace_transfers - replace transfers with several transfers + * and register change with spi_message.resources + * @msg: the spi_message we work upon + * @xfer: the spi_transfer we want to replace + * @remove: number of transfers to remove + * @insert: the number of transfers we want to insert + * @release: extra release code necessary in some circumstances + * + * Returns: pointer to array of newly inserted transfers, + * NULL in case of errors + */ +struct spi_transfer *spi_replace_transfers(struct spi_message *msg, + struct spi_transfer *xfer, + int remove, int insert, + spi_res_release_t release) +{ + int i; + size_t size = insert * sizeof(struct spi_transfer) + + sizeof(struct spi_res_replaced_transfers); + struct spi_res_replaced_transfers *srt; + struct spi_transfer *next; + + if (unlikely(insert < 1)) + return NULL; + + /* allocate the structure */ + srt = spi_res_alloc(msg->spi, __spi_replace_transfers_release, + size, 0); + if (unlikely(!srt)) + return NULL; + + /* the release code to use before running the generic release */ + srt->release = release; + + /* create copy of the given xfer with identical settings */ + srt->inserted = insert; + for (i = 0; i < insert ; i++) { + /* copy all settings */ + memcpy(&srt->xfers[i], xfer, sizeof(*xfer)); + + /* for anything but the last transfer, clear some settings */ + if (i < insert - 1) { + srt->xfers[i].cs_change = 0; + srt->xfers[i].delay_usecs = 0; + } + + /* add before the xfer to remove itself */ + list_add_tail(&srt->xfers[i].transfer_list, + &xfer->transfer_list); + } + + /* remove the requested number of transfers */ + for (i = 0; i < remove; i++, xfer = next) { + /* check for error case - we want to remove list_head...*/ + if (&xfer->transfer_list == &msg->transfers) { + dev_err(&msg->spi->dev, + "requested to remove more spi_transfers than are available\n"); + spi_res_free(srt); + return NULL; + } + /* get the next xfer for later */ + next = list_next_entry(xfer, transfer_list); + + /* and remove the current transfer from the list of transfers */ + list_del_init(&xfer->transfer_list); + + /* and add it to the list in spi_res_replaced_transfers */ + INIT_LIST_HEAD(&srt->replaced_transfers); + list_add(&xfer->transfer_list, &srt->replaced_transfers); + } + + /* and register it */ + spi_res_add(msg, srt); + + /* return the head of the list */ + return &srt->xfers[0]; +} +EXPORT_SYMBOL_GPL(spi_replace_transfers); + +/* core spi_transfer transformation */ + +static void __spi_split_transfers_fixup_transfer_addr_and_len( + struct spi_transfer *xfer, int count, int shift) +{ + int i; + + /* fix up transfer length */ + xfer[0].len = shift; + + /* shift all the addresses arround */ + for (i = 1; i < count; i++) { + xfer[i].len -= shift; + xfer[i].tx_buf += xfer[i].tx_buf ? shift : 0; + xfer[i].rx_buf += xfer[i].rx_buf ? shift : 0; + xfer[i].tx_dma += xfer[i].tx_dma ? shift : 0; + xfer[i].rx_dma += xfer[i].rx_dma ? shift : 0; + } +} + +static int __spi_split_transfers_first_page_len_not_aligned( + struct spi_master *master, + struct spi_message *message, + struct spi_transfer *xfer, + size_t alignment_mask) +{ + int count; + struct spi_transfer *xfers; + const char *tx_start, *rx_start; /* the rx/tx_buf address */ + const char *tx_end, *rx_end; /* the last byte of the transfer */ + size_t tx_start_page, rx_start_page; /* the "page address" for start */ + size_t tx_end_page, rx_end_page; /* the "page address" for end */ + size_t tx_start_align, rx_start_align; /* alignment of buf address */ + + /* calculate the necessary values */ + tx_start = xfer->tx_buf; + tx_start_page = (size_t)tx_start & (PAGE_SIZE - 1); + tx_start_align = ((size_t)tx_start & alignment_mask); + tx_end = tx_start ? &tx_start[xfer->len - 1] : NULL; + tx_end_page = (size_t)tx_end & (PAGE_SIZE - 1); + + rx_start = xfer->rx_buf; + rx_start_page = (size_t)rx_start & (PAGE_SIZE - 1); + rx_start_align = ((size_t)rx_start & alignment_mask); + rx_end = rx_start ? &tx_start[xfer->len - 1] : NULL; + rx_end_page = (size_t)rx_end & (PAGE_SIZE - 1); + + /* if we do not cross a page for either rx or tx, + * then there is nothing to do... + */ + if ((tx_start_page == tx_end_page) && + (rx_start_page == rx_end_page)) + return 0; + + /* calculate how many transfers we need to replace the current */ + count = 1; + if (rx_start_align) + count++; + if ((tx_start_align) && + (tx_start_align != rx_start_align) && + (tx_start != rx_start)) + count++; + + /* send a one-time warning */ + dev_warn_once(&message->spi->dev, + "unaligned spi_transfers produced by spi_device driver - please fix driver\n"); + + /* create replacement */ + xfers = spi_replace_transfers(message, xfer, 1, count, NULL); + if (!xfers) + return -ENOMEM; + + /* now we fix up the transfer pointer and transfer len */ + if (count == 2) { + __spi_split_transfers_fixup_transfer_addr_and_len( + xfers, 2, max(tx_start_align, rx_start_align)); + } else { + if (tx_start_align < rx_start_align) { + __spi_split_transfers_fixup_transfer_addr_and_len( + &xfers[0], 3, + tx_start_align); + __spi_split_transfers_fixup_transfer_addr_and_len( + &xfers[1], 2, + rx_start_align - tx_start_align); + } else { + __spi_split_transfers_fixup_transfer_addr_and_len( + &xfers[0], 3, + rx_start_align); + __spi_split_transfers_fixup_transfer_addr_and_len( + &xfers[1], 2, + tx_start_align - rx_start_align); + } + } + + /* increment statistics counters */ + SPI_STATISTICS_INCREMENT_FIELD(&master->statistics, + transfers_split_unaligned); + SPI_STATISTICS_INCREMENT_FIELD(&message->spi->statistics, + transfers_split_unaligned); + + return 0; +} + +/** + * spi_split_tranfers_first_page_len_not_aligned - split spi transfers into + * two transfers on the + * first page boundary, when + * the start address is not + * aligned + * @master: the @spi_master for this transfer + * @message: the @spi_message to transform + * @when_can_dma: true if we only should execute when we can use dma + * @alignment: the requested alignment + * @min_size: the minimum transfer when to apply this + * + * Return: status of transformation + * + * This implements one of the ways that (dma-enabled) HW may be constrained + * in this case the HW is able to do unaligned transfers, but a DMA-transfer + * is always of size align from a register perspective (even if it only + * writes < align bytes back to ram). + * As there is no guarantee that the next logical page is actually adjectant + * for the dma perspective, we need to split the first page of a transfer + * into separate transfers (1 or 2 depending on alignment of rx_buf and + * tx_buf respectively). + * this does not make sure that the individual transfers that are + * added are address, aligned, but it makes sure that each of those + * new transfers.len is < alignment. + * + */ +int spi_split_transfers_first_page_len_not_aligned( + struct spi_master *master, + struct spi_message *message, + bool when_can_dma, + size_t alignment) +{ + struct spi_device *spi = message->spi; + struct spi_transfer *_xfer, *xfer = NULL; + size_t alignment_mask = alignment - 1; + int ret; + + /* if when_can_dma is set, but can_dma is unset, + * something major is wrong... + */ + if (when_can_dma && (!master->can_dma)) { + dev_err(&master->dev, + "configured without can_dma, but requests can_dma to be set calling first_page_len_not_aligned\n"); + return -EINVAL; + } + + /* iterate over the transfer_list in a safe manner + * there is a posibility of replacement and we need to make sure + * we run over all the entries + */ + xfer = list_prepare_entry(xfer, &message->transfers, transfer_list); + list_for_each_entry_safe_continue(xfer, _xfer, + &message->transfers, + transfer_list) { + if (when_can_dma && (!master->can_dma(master, spi, xfer))) + continue; + if (((size_t)xfer->rx_buf & alignment_mask) || + ((size_t)xfer->tx_buf & alignment_mask)) { + ret = __spi_split_transfers_first_page_len_not_aligned( + master, message, xfer, alignment_mask); + if (ret) + return ret; + } + } + + return 0; +} +EXPORT_SYMBOL_GPL(spi_split_transfers_first_page_len_not_aligned); + +int __spi_split_transfer_maxsize(struct spi_master *master, + struct spi_message *msg, + struct spi_transfer *xfer, + size_t maxsize) +{ + int count = DIV_ROUND_UP(xfer->len, maxsize); + size_t offset = 0; + int i; + struct spi_transfer *xfers; + + /* create replacement */ + xfers = spi_replace_transfers(msg, xfer, 1, count, NULL); + if (!xfers) + return -ENOMEM; + + /* now handle each of those newly inserted xfers */ + for (i = 0; i < count; i++) { + /* the first transfer just needs the length modified, + * so do not change the pointers + */ + if (i) { + /* update rx_buf if it is not tx_buf */ + if (xfers[i].rx_buf && + (xfers[i].tx_buf != xfers[i].rx_buf)) { + /* modify the rx_buf */ + xfers[i].rx_buf += offset; + /* this is actually not used with any + * scatter_lists, but it is still there, + * so we have to support it + */ + if (xfers[i].rx_dma) + xfers[i].rx_dma += offset; + } + /* update tx_buf */ + if (xfers[i].tx_buf) { + /* modify the rx_buf */ + xfers[i].tx_buf += offset; + /* this is actually not used with any + * scatter_lists, but it is still there, + * so we have to support it... + */ + if (xfers[i].tx_dma) + xfers[i].tx_dma += offset; + } + } + /* modify length */ + if (i < count - 1) /* for all but the last transfer */ + xfers[i].len = maxsize; + else /* the last one is most likley not max_size */ + xfers[i].len -= offset; + + /* increment offset */ + offset += maxsize; + } + + /* increment statistics counters */ + SPI_STATISTICS_INCREMENT_FIELD(&master->statistics, + transfers_split_maxsize); + SPI_STATISTICS_INCREMENT_FIELD(&msg->spi->statistics, + transfers_split_maxsize); + + return 0; +} + +/** + * spi_split_tranfers_maxsize - split spi transfers into multiple transfers + * when an individual transfer exceeds a + * certain size + * @master: the @spi_master for this transfer + * @message: the @spi_message to transform + * @max_size: the maximum when to apply this + * + * Return: status of transformation + */ + +int spi_split_transfers_maxsize(struct spi_master *master, + struct spi_message *msg, + size_t maxsize) +{ + struct spi_transfer *_xfer, *xfer = NULL; + int ret; + + /* iterate over the transfer_list in a safe manner + * there is a posibility of replacement and we need to make sure + * we run over all the entries + */ + xfer = list_prepare_entry(xfer, &msg->transfers, transfer_list); + list_for_each_entry_safe_continue(xfer, _xfer, + &msg->transfers, + transfer_list) { + if (xfer->len > maxsize) { + ret = __spi_split_transfer_maxsize( + master, msg, xfer, maxsize); + if (ret) + return ret; + } + } + + return 0; +} +EXPORT_SYMBOL_GPL(spi_split_transfers_maxsize); /*-------------------------------------------------------------------------*/ diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index 7e74e0e..8075c93 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -53,6 +53,11 @@ extern struct bus_type spi_bus_type; * * @transfer_bytes_histo: * transfer bytes histogramm + * + * @transfers_split_maxsize: + * number of transfers split because of len exceeds maxsize + * @transfers_split_unaligned: + * number of transfers split because of unaligned transfers */ struct spi_statistics { spinlock_t lock; /* lock for the whole structure */ @@ -72,6 +77,10 @@ struct spi_statistics { #define SPI_STATISTICS_HISTO_SIZE 17 unsigned long transfer_bytes_histo[SPI_STATISTICS_HISTO_SIZE]; + + unsigned long transfers_split_maxsize; + unsigned long transfers_split_unaligned; + }; void spi_statistics_add_transfer_stats(struct spi_statistics *stats, @@ -607,6 +616,24 @@ extern void spi_res_free(void *res); extern void spi_res_release(struct spi_master *master, struct spi_message *message); +/* SPI transfer modifications using spi_res */ + +extern struct spi_transfer *spi_replace_transfers( + struct spi_message *msg, + struct spi_transfer *xfer, + int remove, int insert, + spi_res_release_t release); + +extern int spi_split_transfers_first_page_len_not_aligned( + struct spi_master *master, + struct spi_message *message, + bool when_can_dma, + size_t alignment); + +extern int spi_split_transfers_maxsize(struct spi_master *master, + struct spi_message *msg, + size_t maxsize); + /*---------------------------------------------------------------------------*/ /*

[2/3] spi: add initial set of spi_transfer transformation methods

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