spi: Add APIs in spi core to set/get spi->chip_select and spi->cs_gpiod

Supporting multi-cs in spi core and spi controller drivers would require
the chip_select & cs_gpiod members of struct spi_device to be an array.
But changing the type of these members to array would break the spi driver
functionality. To make the transition smoother introduced four new APIs to
get/set the spi->chip_select & spi->cs_gpiod and replaced all
spi->chip_select and spi->cs_gpiod references in spi core with the API
calls.
While adding multi-cs support in further patches the chip_select & cs_gpiod
members of the spi_device structure would be converted to arrays & the
"idx" parameter of the APIs would be used as array index i.e.,
spi->chip_select[idx] & spi->cs_gpiod[idx] respectively.

Suggested-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Amit Kumar Mahapatra <amit.kumar-mahapatra@amd.com>
Reviewed-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/20230119185342.2093323-2-amit.kumar-mahapatra@amd.com
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi.c

@@ -604,7 +604,7 @@ static void spi_dev_set_name(struct spi_device *spi)
 	}
 
 	dev_set_name(&spi->dev, "%s.%u", dev_name(&spi->controller->dev),
-		     spi->chip_select);
+		     spi_get_chipselect(spi, 0));
 }
 
 static int spi_dev_check(struct device *dev, void *data)
@@ -613,7 +613,7 @@ static int spi_dev_check(struct device *dev, void *data)
 	struct spi_device *new_spi = data;
 
 	if (spi->controller == new_spi->controller &&
-	    spi->chip_select == new_spi->chip_select)
+	    spi_get_chipselect(spi, 0) == spi_get_chipselect(new_spi, 0))
 		return -EBUSY;
 	return 0;
 }
@@ -638,7 +638,7 @@ static int __spi_add_device(struct spi_device *spi)
 	status = bus_for_each_dev(&spi_bus_type, NULL, spi, spi_dev_check);
 	if (status) {
 		dev_err(dev, "chipselect %d already in use\n",
-				spi->chip_select);
+				spi_get_chipselect(spi, 0));
 		return status;
 	}
 
@@ -649,7 +649,7 @@ static int __spi_add_device(struct spi_device *spi)
 	}
 
 	if (ctlr->cs_gpiods)
-		spi->cs_gpiod = ctlr->cs_gpiods[spi->chip_select];
+		spi_set_csgpiod(spi, 0, ctlr->cs_gpiods[spi_get_chipselect(spi, 0)]);
 
 	/*
 	 * Drivers may modify this initial i/o setup, but will
@@ -692,8 +692,8 @@ int spi_add_device(struct spi_device *spi)
 	int status;
 
 	/* Chipselects are numbered 0..max; validate. */
-	if (spi->chip_select >= ctlr->num_chipselect) {
-		dev_err(dev, "cs%d >= max %d\n", spi->chip_select,
+	if (spi_get_chipselect(spi, 0) >= ctlr->num_chipselect) {
+		dev_err(dev, "cs%d >= max %d\n", spi_get_chipselect(spi, 0),
 			ctlr->num_chipselect);
 		return -EINVAL;
 	}
@@ -714,8 +714,8 @@ static int spi_add_device_locked(struct spi_device *spi)
 	struct device *dev = ctlr->dev.parent;
 
 	/* Chipselects are numbered 0..max; validate. */
-	if (spi->chip_select >= ctlr->num_chipselect) {
-		dev_err(dev, "cs%d >= max %d\n", spi->chip_select,
+	if (spi_get_chipselect(spi, 0) >= ctlr->num_chipselect) {
+		dev_err(dev, "cs%d >= max %d\n", spi_get_chipselect(spi, 0),
 			ctlr->num_chipselect);
 		return -EINVAL;
 	}
@@ -761,7 +761,7 @@ struct spi_device *spi_new_device(struct spi_controller *ctlr,
 
 	WARN_ON(strlen(chip->modalias) >= sizeof(proxy->modalias));
 
-	proxy->chip_select = chip->chip_select;
+	spi_set_chipselect(proxy, 0, chip->chip_select);
 	proxy->max_speed_hz = chip->max_speed_hz;
 	proxy->mode = chip->mode;
 	proxy->irq = chip->irq;
@@ -970,24 +970,23 @@ static void spi_set_cs(struct spi_device *spi, bool enable, bool force)
 	 * Avoid calling into the driver (or doing delays) if the chip select
 	 * isn't actually changing from the last time this was called.
 	 */
-	if (!force && ((enable && spi->controller->last_cs == spi->chip_select) ||
-				(!enable && spi->controller->last_cs != spi->chip_select)) &&
+	if (!force && ((enable && spi->controller->last_cs == spi_get_chipselect(spi, 0)) ||
+		       (!enable && spi->controller->last_cs != spi_get_chipselect(spi, 0))) &&
 	    (spi->controller->last_cs_mode_high == (spi->mode & SPI_CS_HIGH)))
 		return;
 
 	trace_spi_set_cs(spi, activate);
 
-	spi->controller->last_cs = enable ? spi->chip_select : -1;
+	spi->controller->last_cs = enable ? spi_get_chipselect(spi, 0) : -1;
 	spi->controller->last_cs_mode_high = spi->mode & SPI_CS_HIGH;
 
-	if ((spi->cs_gpiod || !spi->controller->set_cs_timing) && !activate) {
+	if ((spi_get_csgpiod(spi, 0) || !spi->controller->set_cs_timing) && !activate)
 		spi_delay_exec(&spi->cs_hold, NULL);
-	}
 
 	if (spi->mode & SPI_CS_HIGH)
 		enable = !enable;
 
-	if (spi->cs_gpiod) {
+	if (spi_get_csgpiod(spi, 0)) {
 		if (!(spi->mode & SPI_NO_CS)) {
 			/*
 			 * Historically ACPI has no means of the GPIO polarity and
@@ -1000,10 +999,10 @@ static void spi_set_cs(struct spi_device *spi, bool enable, bool force)
 			 * into account.
 			 */
 			if (has_acpi_companion(&spi->dev))
-				gpiod_set_value_cansleep(spi->cs_gpiod, !enable);
+				gpiod_set_value_cansleep(spi_get_csgpiod(spi, 0), !enable);
 			else
 				/* Polarity handled by GPIO library */
-				gpiod_set_value_cansleep(spi->cs_gpiod, activate);
+				gpiod_set_value_cansleep(spi_get_csgpiod(spi, 0), activate);
 		}
 		/* Some SPI masters need both GPIO CS & slave_select */
 		if ((spi->controller->flags & SPI_MASTER_GPIO_SS) &&
@@ -1013,7 +1012,7 @@ static void spi_set_cs(struct spi_device *spi, bool enable, bool force)
 		spi->controller->set_cs(spi, !enable);
 	}
 
-	if (spi->cs_gpiod || !spi->controller->set_cs_timing) {
+	if (spi_get_csgpiod(spi, 0) || !spi->controller->set_cs_timing) {
 		if (activate)
 			spi_delay_exec(&spi->cs_setup, NULL);
 		else
@@ -2304,7 +2303,7 @@ static int of_spi_parse_dt(struct spi_controller *ctlr, struct spi_device *spi,
 			nc, rc);
 		return rc;
 	}
-	spi->chip_select = value;
+	spi_set_chipselect(spi, 0, value);
 
 	/* Device speed */
 	if (!of_property_read_u32(nc, "spi-max-frequency", &value))
@@ -2423,7 +2422,7 @@ struct spi_device *spi_new_ancillary_device(struct spi_device *spi,
 	strscpy(ancillary->modalias, "dummy", sizeof(ancillary->modalias));
 
 	/* Use provided chip-select for ancillary device */
-	ancillary->chip_select = chip_select;
+	spi_set_chipselect(ancillary, 0, chip_select);
 
 	/* Take over SPI mode/speed from SPI main device */
 	ancillary->max_speed_hz = spi->max_speed_hz;
@@ -2670,7 +2669,7 @@ struct spi_device *acpi_spi_device_alloc(struct spi_controller *ctlr,
 	spi->mode		|= lookup.mode;
 	spi->irq		= lookup.irq;
 	spi->bits_per_word	= lookup.bits_per_word;
-	spi->chip_select	= lookup.chip_select;
+	spi_set_chipselect(spi, 0, lookup.chip_select);
 
 	return spi;
 }
@@ -3632,7 +3631,7 @@ static int spi_set_cs_timing(struct spi_device *spi)
 	struct device *parent = spi->controller->dev.parent;
 	int status = 0;
 
-	if (spi->controller->set_cs_timing && !spi->cs_gpiod) {
+	if (spi->controller->set_cs_timing && !spi_get_csgpiod(spi, 0)) {
 		if (spi->controller->auto_runtime_pm) {
 			status = pm_runtime_get_sync(parent);
 			if (status < 0) {
@@ -3837,7 +3836,7 @@ static int __spi_validate(struct spi_device *spi, struct spi_message *message)
 	 * cs_change is set for each transfer.
 	 */
 	if ((spi->mode & SPI_CS_WORD) && (!(ctlr->mode_bits & SPI_CS_WORD) ||
-					  spi->cs_gpiod)) {
+					  spi_get_csgpiod(spi, 0))) {
 		size_t maxsize;
 		int ret;
 

include/linux/spi/spi.h

@@ -263,6 +263,26 @@ static inline void *spi_get_drvdata(struct spi_device *spi)
 	return dev_get_drvdata(&spi->dev);
 }
 
+static inline u8 spi_get_chipselect(struct spi_device *spi, u8 idx)
+{
+	return spi->chip_select;
+}
+
+static inline void spi_set_chipselect(struct spi_device *spi, u8 idx, u8 chipselect)
+{
+	spi->chip_select = chipselect;
+}
+
+static inline struct gpio_desc *spi_get_csgpiod(struct spi_device *spi, u8 idx)
+{
+	return spi->cs_gpiod;
+}
+
+static inline void spi_set_csgpiod(struct spi_device *spi, u8 idx, struct gpio_desc *csgpiod)
+{
+	spi->cs_gpiod = csgpiod;
+}
+
 struct spi_message;
 
 /**