From 027781f3920ad16f40133890fc87247b8baa2d8d Mon Sep 17 00:00:00 2001 From: =?utf8?q?Leonard=20G=C3=B6hrs?= Date: Fri, 10 Mar 2023 10:20:52 +0100 Subject: [PATCH] spi: core: add spi_split_transfers_maxwords MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Add spi_split_transfers_maxwords() function that splits spi_transfers transparently into multiple transfers that are below a given number of SPI words. This function reuses most of its code from spi_split_transfers_maxsize() and for transfers with eight or less bits per word actually behaves the same. Signed-off-by: Leonard Göhrs Link: https://lore.kernel.org/r/20230310092053.1006459-1-l.goehrs@pengutronix.de Signed-off-by: Mark Brown --- drivers/spi/spi.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++ include/linux/spi/spi.h | 4 ++++ 2 files changed, 53 insertions(+) diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index c725b4bab7af..9036d7a50674 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -3622,6 +3622,55 @@ int spi_split_transfers_maxsize(struct spi_controller *ctlr, } EXPORT_SYMBOL_GPL(spi_split_transfers_maxsize); + +/** + * spi_split_transfers_maxwords - split spi transfers into multiple transfers + * when an individual transfer exceeds a + * certain number of SPI words + * @ctlr: the @spi_controller for this transfer + * @msg: the @spi_message to transform + * @maxwords: the number of words to limit each transfer to + * @gfp: GFP allocation flags + * + * Return: status of transformation + */ +int spi_split_transfers_maxwords(struct spi_controller *ctlr, + struct spi_message *msg, + size_t maxwords, + gfp_t gfp) +{ + struct spi_transfer *xfer; + + /* + * Iterate over the transfer_list, + * but note that xfer is advanced to the last transfer inserted + * to avoid checking sizes again unnecessarily (also xfer does + * potentially belong to a different list by the time the + * replacement has happened). + */ + list_for_each_entry(xfer, &msg->transfers, transfer_list) { + size_t maxsize; + int ret; + + if (xfer->bits_per_word <= 8) + maxsize = maxwords; + else if (xfer->bits_per_word <= 16) + maxsize = 2 * maxwords; + else + maxsize = 4 * maxwords; + + if (xfer->len > maxsize) { + ret = __spi_split_transfer_maxsize(ctlr, msg, &xfer, + maxsize, gfp); + if (ret) + return ret; + } + } + + return 0; +} +EXPORT_SYMBOL_GPL(spi_split_transfers_maxwords); + /*-------------------------------------------------------------------------*/ /* Core methods for SPI controller protocol drivers. Some of the diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index 74bff5a2f53d..873ced6ae4ca 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -1295,6 +1295,10 @@ extern int spi_split_transfers_maxsize(struct spi_controller *ctlr, struct spi_message *msg, size_t maxsize, gfp_t gfp); +extern int spi_split_transfers_maxwords(struct spi_controller *ctlr, + struct spi_message *msg, + size_t maxwords, + gfp_t gfp); /*---------------------------------------------------------------------------*/ -- 2.11.0