spi: make `cs_change_delay` the first user of the `spi_delay` logic

Since the logic for `spi_delay` struct + `spi_delay_exec()` has been copied
from the `cs_change_delay` logic, it's natural to make this delay, the
first user.

The `cs_change_delay` logic requires that the default remain 10 uS, in case
it is unspecified/unconfigured. So, there is some special handling needed
to do that.

The ADIS library is one of the few users of the new `cs_change_delay`
parameter for an spi_transfer.

The introduction of the `spi_delay` struct, requires that the users of of
`cs_change_delay` get an update. This change also updates the ADIS library.

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20190926105147.7839-4-alexandru.ardelean@analog.com
Signed-off-by: Mark Brown <broonie@kernel.org>

2 files changed, 19 insertions, 33 deletions

diff --git a/drivers/iio/imu/adis.c b/drivers/iio/imu/adis.c
index 1631c255deab..2cd2cc2316c6 100644
--- a/drivers/iio/imu/adis.c
+++ b/drivers/iio/imu/adis.c
@@ -39,24 +39,24 @@ int adis_write_reg(struct adis *adis, unsigned int reg,
 			.len = 2,
 			.cs_change = 1,
 			.delay_usecs = adis->data->write_delay,
-			.cs_change_delay = adis->data->cs_change_delay,
-			.cs_change_delay_unit = SPI_DELAY_UNIT_USECS,
+			.cs_change_delay.value = adis->data->cs_change_delay,
+			.cs_change_delay.unit = SPI_DELAY_UNIT_USECS,
 		}, {
 			.tx_buf = adis->tx + 2,
 			.bits_per_word = 8,
 			.len = 2,
 			.cs_change = 1,
 			.delay_usecs = adis->data->write_delay,
-			.cs_change_delay = adis->data->cs_change_delay,
-			.cs_change_delay_unit = SPI_DELAY_UNIT_USECS,
+			.cs_change_delay.value = adis->data->cs_change_delay,
+			.cs_change_delay.unit = SPI_DELAY_UNIT_USECS,
 		}, {
 			.tx_buf = adis->tx + 4,
 			.bits_per_word = 8,
 			.len = 2,
 			.cs_change = 1,
 			.delay_usecs = adis->data->write_delay,
-			.cs_change_delay = adis->data->cs_change_delay,
-			.cs_change_delay_unit = SPI_DELAY_UNIT_USECS,
+			.cs_change_delay.value = adis->data->cs_change_delay,
+			.cs_change_delay.unit = SPI_DELAY_UNIT_USECS,
 		}, {
 			.tx_buf = adis->tx + 6,
 			.bits_per_word = 8,
@@ -139,16 +139,16 @@ int adis_read_reg(struct adis *adis, unsigned int reg,
 			.len = 2,
 			.cs_change = 1,
 			.delay_usecs = adis->data->write_delay,
-			.cs_change_delay = adis->data->cs_change_delay,
-			.cs_change_delay_unit = SPI_DELAY_UNIT_USECS,
+			.cs_change_delay.value = adis->data->cs_change_delay,
+			.cs_change_delay.unit = SPI_DELAY_UNIT_USECS,
 		}, {
 			.tx_buf = adis->tx + 2,
 			.bits_per_word = 8,
 			.len = 2,
 			.cs_change = 1,
 			.delay_usecs = adis->data->read_delay,
-			.cs_change_delay = adis->data->cs_change_delay,
-			.cs_change_delay_unit = SPI_DELAY_UNIT_USECS,
+			.cs_change_delay.value = adis->data->cs_change_delay,
+			.cs_change_delay.unit = SPI_DELAY_UNIT_USECS,
 		}, {
 			.tx_buf = adis->tx + 4,
 			.rx_buf = adis->rx,
@@ -156,8 +156,8 @@ int adis_read_reg(struct adis *adis, unsigned int reg,
 			.len = 2,
 			.cs_change = 1,
 			.delay_usecs = adis->data->read_delay,
-			.cs_change_delay = adis->data->cs_change_delay,
-			.cs_change_delay_unit = SPI_DELAY_UNIT_USECS,
+			.cs_change_delay.value = adis->data->cs_change_delay,
+			.cs_change_delay.unit = SPI_DELAY_UNIT_USECS,
 		}, {
 			.rx_buf = adis->rx + 2,
 			.bits_per_word = 8,
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 7499a4efbaba..b69c14082c52 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1160,9 +1160,9 @@ EXPORT_SYMBOL_GPL(spi_delay_exec);
 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;
-	u32 hz;
+	u32 delay = xfer->cs_change_delay.value;
+	u32 unit = xfer->cs_change_delay.unit;
+	int ret;
 
 	/* return early on "fast" mode - for everything but USECS */
 	if (!delay) {
@@ -1171,27 +1171,13 @@ static void _spi_transfer_cs_change_delay(struct spi_message *msg,
 		return;
 	}
 
-	switch (unit) {
-	case SPI_DELAY_UNIT_USECS:
-		delay *= 1000;
-		break;
-	case SPI_DELAY_UNIT_NSECS: /* nothing to do here */
-		break;
-	case SPI_DELAY_UNIT_SCK:
-		/* if there is no effective speed know, then approximate
-		 * by underestimating with half the requested hz
-		 */
-		hz = xfer->effective_speed_hz ?: xfer->speed_hz / 2;
-		delay *= DIV_ROUND_UP(1000000000, hz);
-		break;
-	default:
+	ret = spi_delay_exec(&xfer->cs_change_delay, xfer);
+	if (ret) {
 		dev_err_once(&msg->spi->dev,
 			     "Use of unsupported delay unit %i, using default of 10us\n",
-			     xfer->cs_change_delay_unit);
-		delay = 10000;
+			     unit);
+		_spi_transfer_delay_ns(10000);
 	}
-	/* now sleep for the requested amount of time */
-	_spi_transfer_delay_ns(delay);
 }
 
 /*