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authorLars-Peter Clausen <lars@metafoo.de>2013-01-09 21:31:00 +0400
committerJonathan Cameron <jic23@kernel.org>2013-02-09 15:02:07 +0400
commit6d9eecd418afb2c12e5db5be3d72f0f1df43bdd9 (patch)
tree6c9fc5330e8e6970ab08f1c1220d612caeb44344 /include/linux/spi
parentad76fda78318821fe8823b4b7c587a46a268eecf (diff)
downloadlinux-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/spi')
-rw-r--r--include/linux/spi/spi.h44
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,