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Subject[PATCH v4 08/19] spi: introduce `delay` field for `spi_transfer` + spi_transfer_delay_exec()
Date
The change introduces the `delay` field to the `spi_transfer` struct as an
`struct spi_delay` type.
This intends to eventually replace `delay_usecs`.

But, since there are many users of `delay_usecs`, this needs some
intermediate work.
A helper called `spi_transfer_delay_exec()` is also added, which maintains
backwards compatibility with `delay_usecs`, by assigning the value to
`delay` if non-zero.
This should maintain backwards compatibility with current users of
`udelay_usecs`.

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
---
drivers/spi/spi.c | 6 +++---
include/linux/spi/spi.h | 18 ++++++++++++++++++
2 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index ba8731b77753..489eb64d9ee0 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1238,8 +1238,7 @@ static int spi_transfer_one_message(struct spi_controller *ctlr,
if (msg->status != -EINPROGRESS)
goto out;

- if (xfer->delay_usecs)
- _spi_transfer_delay_ns(xfer->delay_usecs * 1000);
+ spi_transfer_delay_exec(xfer);

if (xfer->cs_change) {
if (list_is_last(&xfer->transfer_list,
@@ -2904,10 +2903,11 @@ struct spi_replaced_transfers *spi_replace_transfers(
/* add to list */
list_add(&xfer->transfer_list, rxfer->replaced_after);

- /* clear cs_change and delay_usecs for all but the last */
+ /* clear cs_change and delay for all but the last */
if (i) {
xfer->cs_change = false;
xfer->delay_usecs = 0;
+ xfer->delay.value = 0;
}
}

diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index e7ec0be16a82..2cee9ac35737 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -754,6 +754,9 @@ extern void spi_res_release(struct spi_controller *ctlr,
* @cs_change: affects chipselect after this transfer completes
* @cs_change_delay: delay between cs deassert and assert when
* @cs_change is set and @spi_transfer is not the last in @spi_message
+ * @delay: delay to be introduced after this transfer before
+ * (optionally) changing the chipselect status, then starting
+ * the next transfer or completing this @spi_message.
* @delay_usecs: microseconds to delay after this transfer before
* (optionally) changing the chipselect status, then starting
* the next transfer or completing this @spi_message.
@@ -843,6 +846,7 @@ struct spi_transfer {
#define SPI_NBITS_QUAD 0x04 /* 4bits transfer */
u8 bits_per_word;
u16 delay_usecs;
+ struct spi_delay delay;
struct spi_delay cs_change_delay;
struct spi_delay word_delay;
u32 speed_hz;
@@ -942,6 +946,20 @@ spi_transfer_del(struct spi_transfer *t)
list_del(&t->transfer_list);
}

+static inline int
+spi_transfer_delay_exec(struct spi_transfer *t)
+{
+ struct spi_delay d;
+
+ if (t->delay_usecs) {
+ d.value = t->delay_usecs;
+ d.unit = SPI_DELAY_UNIT_USECS;
+ return spi_delay_exec(&d, NULL);
+ }
+
+ return spi_delay_exec(&t->delay, t);
+}
+
/**
* spi_message_init_with_transfers - Initialize spi_message and append transfers
* @m: spi_message to be initialized
--
2.20.1
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