spi: introduce `delay` field for `spi_transfer` + spi_transfer_delay_exec()

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>
Link: https://lore.kernel.org/r/20190926105147.7839-9-alexandru.ardelean@analog.com
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 307e440dd92d50f53209ee45df4289c4582e3eb7..2e448078a117f15c01989da6d6d36ffa3a4ef284 100644 (file)
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1248,8 +1248,7 @@ 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,
@@ -3026,10 +3025,11 @@ 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 ebeb272aeb0f6d38474e6d8386f4b336b426ee96..fe5b85df2c79830671f322b37e131a4ce8dd7370 100644 (file)
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -778,6 +778,9 @@ 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.
@@ -896,6 +899,7 @@ 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;
@@ -1003,6 +1007,20 @@ 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