[U-Boot] [PATCH v2 3/4] dm: spi: Check cs number before accessing slaves

[Bin Meng <bmeng.cn@gmail.com>]

Add chip select number check in spi_find_chip_select().

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>

---

Changes in v2:
- move the chip select number check to spi_find_chip_select()

 drivers/spi/spi-uclass.c | 45 ++++++++++++++++++++++++++-------------------
 include/spi.h            |  3 ++-
 2 files changed, 28 insertions(+), 20 deletions(-)

diff --git a/drivers/spi/spi-uclass.c b/drivers/spi/spi-uclass.c
index 24de0b5..cdeceb5 100644
--- a/drivers/spi/spi-uclass.c
+++ b/drivers/spi/spi-uclass.c
@@ -179,7 +179,32 @@ int spi_chip_select(struct udevice *dev)
 
 int spi_find_chip_select(struct udevice *bus, int cs, struct udevice **devp)
 {
+	struct dm_spi_ops *ops;
+	struct spi_cs_info info;
 	struct udevice *dev;
+	int ret;
+
+	/*
+	 * Ask the driver. For the moment we don't have CS info.
+	 * When we do we could provide the driver with a helper function
+	 * to figure out what chip selects are valid, or just handle the
+	 * request.
+	 */
+	ops = spi_get_ops(bus);
+	if (ops->cs_info) {
+		ret = ops->cs_info(bus, cs, &info);
+	} else {
+		/*
+		 * We could assume there is at least one valid chip select.
+		 * The driver didn't care enough to tell us.
+		 */
+		ret = 0;
+	}
+
+	if (ret) {
+		printf("Invalid cs %d (err=%d)\n", cs, ret);
+		return ret;
+	}
 
 	for (device_find_first_child(bus, &dev); dev;
 	     device_find_next_child(&dev)) {
@@ -214,7 +239,6 @@ int spi_cs_is_valid(unsigned int busnum, unsigned int cs)
 int spi_cs_info(struct udevice *bus, uint cs, struct spi_cs_info *info)
 {
 	struct spi_cs_info local_info;
-	struct dm_spi_ops *ops;
 	int ret;
 
 	if (!info)
@@ -223,24 +247,7 @@ int spi_cs_info(struct udevice *bus, uint cs, struct spi_cs_info *info)
 	/* If there is a device attached, return it */
 	info->dev = NULL;
 	ret = spi_find_chip_select(bus, cs, &info->dev);
-	if (!ret)
-		return 0;
-
-	/*
-	 * Otherwise ask the driver. For the moment we don't have CS info.
-	 * When we do we could provide the driver with a helper function
-	 * to figure out what chip selects are valid, or just handle the
-	 * request.
-	 */
-	ops = spi_get_ops(bus);
-	if (ops->cs_info)
-		return ops->cs_info(bus, cs, info);
-
-	/*
-	 * We could assume there is at least one valid chip select.
-	 * The driver didn't care enough to tell us.
-	 */
-	return 0;
+	return ret == -ENODEV ? 0 : ret;
 }
 
 int spi_find_bus_and_cs(int busnum, int cs, struct udevice **busp,
diff --git a/include/spi.h b/include/spi.h
index cc344de..6b144bc 100644
--- a/include/spi.h
+++ b/include/spi.h
@@ -528,7 +528,8 @@ int spi_chip_select(struct udevice *slave);
  * @bus:	SPI bus to search
  * @cs:		Chip select to look for
  * @devp:	Returns the slave device if found
- * @return 0 if found, -ENODEV on error
+ * @return 0 if found, -EINVAL if cs is invalid, -ENODEV if no device attached,
+ *	   other -ve value on error
  */
 int spi_find_chip_select(struct udevice *bus, int cs, struct udevice **devp);
 
-- 
2.7.4