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-rw-r--r--drivers/spi/spi.c59
-rw-r--r--include/linux/spi/spi.h7
2 files changed, 56 insertions, 10 deletions
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 5e75944ad5d1..7e8ffe3fdc00 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1090,6 +1090,52 @@ static int spi_transfer_wait(struct spi_controller *ctlr,
return 0;
}
+static void _spi_transfer_delay_ns(u32 ns)
+{
+ if (!ns)
+ return;
+ if (ns <= 1000) {
+ ndelay(ns);
+ } else {
+ u32 us = DIV_ROUND_UP(ns, 1000);
+
+ if (us <= 10)
+ udelay(us);
+ else
+ usleep_range(us, us + DIV_ROUND_UP(us, 10));
+ }
+}
+
+static void _spi_transfer_cs_change_delay(struct spi_message *msg,
+ struct spi_transfer *xfer)
+{
+ u32 delay = xfer->cs_change_delay;
+ u32 unit = xfer->cs_change_delay_unit;
+
+ /* return early on "fast" mode - for everything but USECS */
+ if (!delay && unit != SPI_DELAY_UNIT_USECS)
+ return;
+
+ switch (unit) {
+ case SPI_DELAY_UNIT_USECS:
+ /* for compatibility use default of 10us */
+ if (!delay)
+ delay = 10000;
+ else
+ delay *= 1000;
+ break;
+ case SPI_DELAY_UNIT_NSECS: /* nothing to do here */
+ break;
+ default:
+ dev_err_once(&msg->spi->dev,
+ "Use of unsupported delay unit %i, using default of 10us\n",
+ xfer->cs_change_delay_unit);
+ delay = 10000;
+ }
+ /* now sleep for the requested amount of time */
+ _spi_transfer_delay_ns(delay);
+}
+
/*
* spi_transfer_one_message - Default implementation of transfer_one_message()
*
@@ -1148,14 +1194,8 @@ static int spi_transfer_one_message(struct spi_controller *ctlr,
if (msg->status != -EINPROGRESS)
goto out;
- if (xfer->delay_usecs) {
- u16 us = xfer->delay_usecs;
-
- if (us <= 10)
- udelay(us);
- else
- usleep_range(us, us + DIV_ROUND_UP(us, 10));
- }
+ if (xfer->delay_usecs)
+ _spi_transfer_delay_ns(xfer->delay_usecs * 1000);
if (xfer->cs_change) {
if (list_is_last(&xfer->transfer_list,
@@ -1163,7 +1203,7 @@ static int spi_transfer_one_message(struct spi_controller *ctlr,
keep_cs = true;
} else {
spi_set_cs(msg->spi, false);
- udelay(10);
+ _spi_transfer_cs_change_delay(msg, xfer);
spi_set_cs(msg->spi, true);
}
}
@@ -3757,4 +3797,3 @@ err0:
* include needing to have boardinfo data structures be much more public.
*/
postcore_initcall(spi_init);
-
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 053abd22ad31..023beb9e9e4b 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -735,6 +735,9 @@ extern void spi_res_release(struct spi_controller *ctlr,
* @bits_per_word: select a bits_per_word other than the device default
* for this transfer. If 0 the default (from @spi_device) is used.
* @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
+ * @cs_change_delay_unit: unit of cs_change_delay
* @delay_usecs: microseconds to delay after this transfer before
* (optionally) changing the chipselect status, then starting
* the next transfer or completing this @spi_message.
@@ -824,6 +827,10 @@ struct spi_transfer {
u8 bits_per_word;
u8 word_delay_usecs;
u16 delay_usecs;
+ u16 cs_change_delay;
+ u8 cs_change_delay_unit;
+#define SPI_DELAY_UNIT_USECS 0
+#define SPI_DELAY_UNIT_NSECS 1
u32 speed_hz;
u16 word_delay;