Some drivers need to know whether the current transfer is the last in
the message in order to properly handle CS. A common way to achieve
this is to reimplement transfer_one_message() but this leads to
undesirable code duplication.
This patch adds a 'last' field to the spi_transfer structure and
populates it before passing the structure to the driver.
Signed-off-by: Beniamino Galvani <b.galvani@xxxxxxxxx>
---
drivers/spi/spi.c | 6 ++++++
include/linux/spi/spi.h | 2 ++
2 files changed, 8 insertions(+)
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index ebcb33d..fc7f02d 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -887,6 +887,7 @@ static void spi_pump_messages(struct kthread_work *work)
{
struct spi_master *master =
container_of(work, struct spi_master, pump_messages);
+ struct spi_transfer *xfer;
unsigned long flags;
bool was_busy = false;
int ret;
@@ -941,6 +942,11 @@ static void spi_pump_messages(struct kthread_work *work)
}
}
+ list_for_each_entry(xfer, &master->cur_msg->transfers, transfer_list) {
+ xfer->last = list_is_last(&xfer->transfer_list,
+ &master->cur_msg->transfers);
+ }
+
if (!was_busy)
trace_spi_master_busy(master);
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 46d188a..37f055a 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -535,6 +535,7 @@ extern struct spi_master *spi_busnum_to_master(u16 busnum);
* (SPI_NBITS_SINGLE) is used.
* @rx_nbits: number of bits used for reading. If 0 the default
* (SPI_NBITS_SINGLE) is used.
+ * @last: whether the transfer is the last in the message.
* @len: size of rx and tx buffers (in bytes)
* @speed_hz: Select a speed other than the device default for this
* transfer. If 0 the default (from @spi_device) is used.
@@ -620,6 +621,7 @@ struct spi_transfer {
unsigned cs_change:1;
unsigned tx_nbits:3;
unsigned rx_nbits:3;
+ unsigned last:1;
#define SPI_NBITS_SINGLE 0x01 /* 1bit transfer */
#define SPI_NBITS_DUAL 0x02 /* 2bits transfer */
#define SPI_NBITS_QUAD 0x04 /* 4bits transfer */
--
1.9.1
--
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