dm: spi: Change cs_info op to return -EINVAL for invalid cs num

We need distinguish the following two situations in various SPI APIs:

- given chip select num is invalid
- given chip select num is valid, but no device is attached

Currently -ENODEV is returned for both cases.

For the first case, it's more reasonable to return -EINVAL instead of
-ENODEV for invalid chip select numbers.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Tested-by: Jagan Teki <jagan@amarulasolutions.com> # SoPine
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>

doc/driver-model/spi-howto.rst

@@ -116,7 +116,7 @@ Put this code at the bottom of your existing driver file:
 	static int exynos_cs_info(struct udevice *bus, uint cs,
 				  struct spi_cs_info *info)
 	{
-		return -ENODEV;
+		return -EINVAL;
 	}
 
 	static const struct dm_spi_ops exynos_spi_ops = {
@@ -633,7 +633,7 @@ is not obvious from outside the driver. In this case you can provide a
 method for cs_info() to deal with this. If you don't provide it, then the
 device tree will be used to determine what chip selects are valid.
 
-Return -ENODEV if the supplied chip select is invalid, or 0 if it is valid.
+Return -EINVAL if the supplied chip select is invalid, or 0 if it is valid.
 If you don't provide the cs_info() method, 0 is assumed for all chip selects
 that do not appear in the device tree.
 

drivers/spi/ath79_spi.c

@@ -198,7 +198,7 @@ static int ath79_cs_info(struct udevice *bus, uint cs,
 {
 	/* Always allow activity on CS 0/1/2 */
 	if (cs >= 3)
-		return -ENODEV;
+		return -EINVAL;
 
 	return 0;
 }

drivers/spi/bcm63xx_hsspi.c

@@ -108,7 +108,7 @@ static int bcm63xx_hsspi_cs_info(struct udevice *bus, uint cs,
 
 	if (cs >= priv->num_cs) {
 		printf("no cs %u\n", cs);
-		return -ENODEV;
+		return -EINVAL;
 	}
 
 	return 0;

drivers/spi/bcm63xx_spi.c

@@ -130,7 +130,7 @@ static int bcm63xx_spi_cs_info(struct udevice *bus, uint cs,
 
 	if (cs >= priv->num_cs) {
 		printf("no cs %u\n", cs);
-		return -ENODEV;
+		return -EINVAL;
 	}
 
 	return 0;

drivers/spi/sandbox_spi.c

@@ -117,7 +117,7 @@ static int sandbox_cs_info(struct udevice *bus, uint cs,
 {
 	/* Always allow activity on CS 0 */
 	if (cs >= 1)
-		return -ENODEV;
+		return -EINVAL;
 
 	return 0;
 }

drivers/spi/tegra20_sflash.c

@@ -78,7 +78,7 @@ int tegra20_sflash_cs_info(struct udevice *bus, unsigned int cs,
 {
 	/* Tegra20 SPI-Flash - only 1 device ('bus/cs') */
 	if (cs != 0)
-		return -ENODEV;
+		return -EINVAL;
 	else
 		return 0;
 }

include/spi.h

@@ -458,7 +458,7 @@ struct dm_spi_ops {
 	 * @cs:		The chip select (0..n-1)
 	 * @info:	Returns information about the chip select, if valid.
 	 *		On entry info->dev is NULL
-	 * @return 0 if OK (and @info is set up), -ENODEV if the chip select
+	 * @return 0 if OK (and @info is set up), -EINVAL if the chip select
 	 *	   is invalid, other -ve value on error
 	 */
 	int (*cs_info)(struct udevice *bus, uint cs, struct spi_cs_info *info);