spi: Consistently use BIT for cs_index_mask

Some of the parts related to the chip select are using BIT() macro
the rest are using plain numbers. Unify all of them to use BIT().

While at it, make the (repetitive) comment clearer when assigning
cs_index_mask during SPI target device enumeration.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://msgid.link/r/20240307150256.3789138-2-andriy.shevchenko@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi.c

@@ -1021,7 +1021,7 @@ static inline bool spi_is_last_cs(struct spi_device *spi)
 	bool last = false;
 
 	for (idx = 0; idx < SPI_CS_CNT_MAX; idx++) {
-		if ((spi->cs_index_mask >> idx) & 0x01) {
+		if (spi->cs_index_mask & BIT(idx)) {
 			if (spi->controller->last_cs[idx] == spi_get_chipselect(spi, idx))
 				last = true;
 		}
@@ -1072,8 +1072,7 @@ static void spi_set_cs(struct spi_device *spi, bool enable, bool force)
 			 * into account.
 			 */
 			for (idx = 0; idx < SPI_CS_CNT_MAX; idx++) {
-				if (((spi->cs_index_mask >> idx) & 0x01) &&
-				    spi_get_csgpiod(spi, idx)) {
+				if ((spi->cs_index_mask & BIT(idx)) && spi_get_csgpiod(spi, idx)) {
 					if (has_acpi_companion(&spi->dev))
 						gpiod_set_value_cansleep(spi_get_csgpiod(spi, idx),
 									 !enable);
@@ -2456,14 +2455,10 @@ static int of_spi_parse_dt(struct spi_controller *ctlr, struct spi_device *spi,
 		spi_set_chipselect(spi, idx, cs[idx]);
 
 	/*
-	 * spi->chip_select[i] gives the corresponding physical CS for logical CS i
-	 * logical CS number is represented by setting the ith bit in spi->cs_index_mask
-	 * So, for example, if spi->cs_index_mask = 0x01 then logical CS number is 0 and
-	 * spi->chip_select[0] will give the physical CS.
-	 * By default spi->chip_select[0] will hold the physical CS number so, set
-	 * spi->cs_index_mask as 0x01.
+	 * By default spi->chip_select[0] will hold the physical CS number,
+	 * so set bit 0 in spi->cs_index_mask.
 	 */
-	spi->cs_index_mask = 0x01;
+	spi->cs_index_mask = BIT(0);
 
 	/* Device speed */
 	if (!of_property_read_u32(nc, "spi-max-frequency", &value))
@@ -2587,14 +2582,10 @@ struct spi_device *spi_new_ancillary_device(struct spi_device *spi,
 	ancillary->max_speed_hz = spi->max_speed_hz;
 	ancillary->mode = spi->mode;
 	/*
-	 * spi->chip_select[i] gives the corresponding physical CS for logical CS i
-	 * logical CS number is represented by setting the ith bit in spi->cs_index_mask
-	 * So, for example, if spi->cs_index_mask = 0x01 then logical CS number is 0 and
-	 * spi->chip_select[0] will give the physical CS.
-	 * By default spi->chip_select[0] will hold the physical CS number so, set
-	 * spi->cs_index_mask as 0x01.
+	 * By default spi->chip_select[0] will hold the physical CS number,
+	 * so set bit 0 in spi->cs_index_mask.
 	 */
-	ancillary->cs_index_mask = 0x01;
+	ancillary->cs_index_mask = BIT(0);
 
 	WARN_ON(!mutex_is_locked(&ctlr->add_lock));
 
@@ -2841,14 +2832,10 @@ struct spi_device *acpi_spi_device_alloc(struct spi_controller *ctlr,
 	spi->irq		= lookup.irq;
 	spi->bits_per_word	= lookup.bits_per_word;
 	/*
-	 * spi->chip_select[i] gives the corresponding physical CS for logical CS i
-	 * logical CS number is represented by setting the ith bit in spi->cs_index_mask
-	 * So, for example, if spi->cs_index_mask = 0x01 then logical CS number is 0 and
-	 * spi->chip_select[0] will give the physical CS.
-	 * By default spi->chip_select[0] will hold the physical CS number so, set
-	 * spi->cs_index_mask as 0x01.
+	 * By default spi->chip_select[0] will hold the physical CS number,
+	 * so set bit 0 in spi->cs_index_mask.
 	 */
-	spi->cs_index_mask	= 0x01;
+	spi->cs_index_mask	= BIT(0);
 
 	return spi;
 }