diff options
author | Lars-Peter Clausen <lars@metafoo.de> | 2013-01-09 21:31:00 +0400 |
---|---|---|
committer | Jonathan Cameron <jic23@kernel.org> | 2013-02-09 15:02:07 +0400 |
commit | 6d9eecd418afb2c12e5db5be3d72f0f1df43bdd9 (patch) | |
tree | 6c9fc5330e8e6970ab08f1c1220d612caeb44344 /include/linux | |
parent | ad76fda78318821fe8823b4b7c587a46a268eecf (diff) | |
download | linux-6d9eecd418afb2c12e5db5be3d72f0f1df43bdd9.tar.xz |
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 <lars@metafoo.de>
Reviewed-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Diffstat (limited to 'include/linux')
-rw-r--r-- | include/linux/spi/spi.h | 44 |
1 files changed, 44 insertions, 0 deletions
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, |