From 6d9eecd418afb2c12e5db5be3d72f0f1df43bdd9 Mon Sep 17 00:00:00 2001 From: Lars-Peter Clausen Date: Wed, 9 Jan 2013 17:31:00 +0000 Subject: [PATCH] spi: Add helper functions for setting up transfers Quite often the pattern used for setting up and transferring a synchronous SPI transaction looks very much like the following: struct spi_message msg; struct spi_transfer xfers[] = { ... }; spi_message_init(&msg); spi_message_add_tail(&xfers[0], &msg); ... spi_message_add_tail(&xfers[ARRAY_SIZE(xfers) - 1], &msg); ret = spi_sync(&msg); This patch adds two new helper functions for handling this case. The first helper function spi_message_init_with_transfers() takes a spi_message and an array of spi_transfers. It will initialize the message and then call spi_message_add_tail() for each transfer in the array. E.g. the following spi_message_init(&msg); spi_message_add_tail(&xfers[0], &msg); ... spi_message_add_tail(&xfers[ARRAY_SIZE(xfers) - 1], &msg); can be rewritten as spi_message_init_with_transfers(&msg, xfers, ARRAY_SIZE(xfers)); The second function spi_sync_transfer() takes a SPI device and an array of spi_transfers. It will allocate a new spi_message (on the stack) and add all transfers in the array to the message. Finally it will call spi_sync() on the message. E.g. the follwing struct spi_message msg; struct spi_transfer xfers[] = { ... }; spi_message_init(&msg); spi_message_add_tail(&xfers[0], &msg); ... spi_message_add_tail(&xfers[ARRAY_SIZE(xfers) - 1], &msg); ret = spi_sync(spi, &msg); can be rewritten as struct spi_transfer xfers[] = { ... }; ret = spi_sync_transfer(spi, xfers, ARRAY_SIZE(xfers)); A coccinelle script to find such instances will follow. Signed-off-by: Lars-Peter Clausen Reviewed-by: Mark Brown Signed-off-by: Jonathan Cameron --- include/linux/spi/spi.h | 44 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index f62918946d86..7dbe58642525 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -591,6 +591,26 @@ spi_transfer_del(struct spi_transfer *t) list_del(&t->transfer_list); } +/** + * spi_message_init_with_transfers - Initialize spi_message and append transfers + * @m: spi_message to be initialized + * @xfers: An array of spi transfers + * @num_xfers: Number of items in the xfer array + * + * This function initializes the given spi_message and adds each spi_transfer in + * the given array to the message. + */ +static inline void +spi_message_init_with_transfers(struct spi_message *m, +struct spi_transfer *xfers, unsigned int num_xfers) +{ + unsigned int i; + + spi_message_init(m); + for (i = 0; i < num_xfers; ++i) + spi_message_add_tail(&xfers[i], m); +} + /* It's fine to embed message and transaction structures in other data * structures so long as you don't free them while they're in use. */ @@ -683,6 +703,30 @@ spi_read(struct spi_device *spi, void *buf, size_t len) return spi_sync(spi, &m); } +/** + * spi_sync_transfer - synchronous SPI data transfer + * @spi: device with which data will be exchanged + * @xfers: An array of spi_transfers + * @num_xfers: Number of items in the xfer array + * Context: can sleep + * + * Does a synchronous SPI data transfer of the given spi_transfer array. + * + * For more specific semantics see spi_sync(). + * + * It returns zero on success, else a negative error code. + */ +static inline int +spi_sync_transfer(struct spi_device *spi, struct spi_transfer *xfers, + unsigned int num_xfers) +{ + struct spi_message msg; + + spi_message_init_with_transfers(&msg, xfers, num_xfers); + + return spi_sync(spi, &msg); +} + /* this copies txbuf and rxbuf data; for small transfers only! */ extern int spi_write_then_read(struct spi_device *spi, const void *txbuf, unsigned n_tx, -- 2.20.1