iio: imu: adis: Use spi cs inactive delay

A delay is needed each time the chip selected becomes inactive,
even after burst data readings are performed.
Currently, there is no delay added after a burst reading
and in case a new SPI transfer is performed before
the needed delay, the adis device becomes unresponsive until
reset.

This commit is adding the needed delay directly to the spi driver,
using the cs_inactive parameter, in case it is not set and is
removing the additional chip select change delay present in adis
APIs to remove the double delay.
Signed-off-by: Ramona Gradinariu <ramona.gradinariu@analog.com>
Link: https://lore.kernel.org/r/20231027140358.328699-2-ramona.gradinariu@analog.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/imu/adis.c

@@ -44,8 +44,6 @@ int __adis_write_reg(struct adis *adis, unsigned int reg, unsigned int value,
 			.cs_change = 1,
 			.delay.value = adis->data->write_delay,
 			.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,
@@ -53,8 +51,6 @@ int __adis_write_reg(struct adis *adis, unsigned int reg, unsigned int value,
 			.cs_change = 1,
 			.delay.value = adis->data->write_delay,
 			.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,
@@ -62,8 +58,6 @@ int __adis_write_reg(struct adis *adis, unsigned int reg, unsigned int value,
 			.cs_change = 1,
 			.delay.value = adis->data->write_delay,
 			.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,
@@ -144,8 +138,6 @@ int __adis_read_reg(struct adis *adis, unsigned int reg, unsigned int *val,
 			.cs_change = 1,
 			.delay.value = adis->data->write_delay,
 			.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,
@@ -153,8 +145,6 @@ int __adis_read_reg(struct adis *adis, unsigned int reg, unsigned int *val,
 			.cs_change = 1,
 			.delay.value = adis->data->read_delay,
 			.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,
@@ -163,8 +153,6 @@ int __adis_read_reg(struct adis *adis, unsigned int reg, unsigned int *val,
 			.cs_change = 1,
 			.delay.value = adis->data->read_delay,
 			.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,
@@ -524,6 +512,12 @@ int adis_init(struct adis *adis, struct iio_dev *indio_dev,
 	}
 
 	mutex_init(&adis->state_lock);
+
+	if (!spi->cs_inactive.value) {
+		spi->cs_inactive.value = data->cs_change_delay;
+		spi->cs_inactive.unit = SPI_DELAY_UNIT_USECS;
+	}
+
 	adis->spi = spi;
 	adis->data = data;
 	iio_device_set_drvdata(indio_dev, adis);