[PATCH] spi: Fix probing SPI drivers without a cs-gpios node

[John Watts <contact@jookia.org>]

of_gpio_named_count returns a negative value on error but this
is discarded and cast to a u16, making error handling impossible.

With debug logging enabled this effectively halts booting so the board can
print an error over serial 65534 times.

Check for this error and proceed as if there are no gpios specified.

Signed-off-by: John Watts <contact@jookia.org>
---
 drivers/spi/atmel_spi.c | 8 +++++++-
 drivers/spi/imx_spi.c   | 8 +++++++-
 drivers/spi/stm32_spi.c | 8 +++++++-
 3 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/drivers/spi/atmel_spi.c b/drivers/spi/atmel_spi.c
index ec90330e53..a2314be8ee 100644
--- a/drivers/spi/atmel_spi.c
+++ b/drivers/spi/atmel_spi.c
@@ -388,6 +388,7 @@ static int atmel_spi_probe(struct device_d *dev)
 	struct resource *iores;
 	int ret = 0;
 	int i;
+	int num_gpios;
 	struct spi_master *master;
 	struct device_node *node = dev->device_node;
 	struct atmel_spi *as;
@@ -408,7 +409,12 @@ static int atmel_spi_probe(struct device_d *dev)
 		master->num_chipselect = pdata->num_chipselect;
 		as->cs_pins = pdata->chipselect;
 	} else {
-		master->num_chipselect = of_gpio_named_count(node, "cs-gpios");
+		num_gpios = of_gpio_named_count(node, "cs-gpios");
+		if (num_gpios < 0) {
+			num_gpios = 0;
+		}
+
+		master->num_chipselect = num_gpios;
 		as->cs_pins = xzalloc(sizeof(u32) * master->num_chipselect);
 
 		for (i = 0; i < master->num_chipselect; i++) {
diff --git a/drivers/spi/imx_spi.c b/drivers/spi/imx_spi.c
index 3e0ad2db00..b10076639a 100644
--- a/drivers/spi/imx_spi.c
+++ b/drivers/spi/imx_spi.c
@@ -564,11 +564,17 @@ static int imx_spi_dt_probe(struct imx_spi *imx)
 {
 	struct device_node *node = imx->master.dev->device_node;
 	int i;
+	int num_gpios;
 
 	if (!node)
 		return -ENODEV;
 
-	imx->master.num_chipselect = of_gpio_named_count(node, "cs-gpios");
+	num_gpios = of_gpio_named_count(node, "cs-gpios");
+	if (num_gpios < 0) {
+		num_gpios = 0;
+	}
+
+	imx->master.num_chipselect = num_gpios;
 	imx->cs_array = xzalloc(sizeof(u32) * imx->master.num_chipselect);
 
 	for (i = 0; i < imx->master.num_chipselect; i++)
diff --git a/drivers/spi/stm32_spi.c b/drivers/spi/stm32_spi.c
index 639c4f1740..a34e0b143d 100644
--- a/drivers/spi/stm32_spi.c
+++ b/drivers/spi/stm32_spi.c
@@ -513,8 +513,14 @@ static void stm32_spi_dt_probe(struct stm32_spi_priv *priv)
 {
 	struct device_node *node = priv->master.dev->device_node;
 	int i;
+	int num_gpios;
 
-	priv->master.num_chipselect = of_gpio_named_count(node, "cs-gpios");
+	num_gpios = of_gpio_named_count(node, "cs-gpios");
+	if (num_gpios < 0) {
+		num_gpios = 0;
+	}
+
+	priv->master.num_chipselect = num_gpios;
 	priv->cs_gpios = xzalloc(sizeof(u32) * priv->master.num_chipselect);
 
 	for (i = 0; i < priv->master.num_chipselect; i++)
-- 
2.39.0