spi: spi-gpio: Fix compiler warning when building for 64 bit systems

The assignment of SPI_GPIO_NO_CHIPSELECT to cs_gpios[0] causes the following
compiler warning, when building for 64 bit systems:
"warning: overflow in implicit constant conversion [-Woverflow]".

This is because the SPI_GPIO_NO_CHIPSELECT flag is a '-1' type casted to
unsigned long and cs_gpios is of the type int.

Furthermore the chip select's GPIO number is locally stored as unsigned int
and compared with SPI_GPIO_NO_CHIPSELECT. Thus the result of the comparison
is always false, if unsigned long and unsigned int have a different size.

As part of the fix this patch adds a check for the device tree's cs-gpios
property.

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Signed-off-by: Torsten Fleischer <torfl6749@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 15 insertions, 9 deletions

diff --git a/drivers/spi/spi-gpio.c b/drivers/spi/spi-gpio.c
index f0492c99d145..4b600d4f8548 100644
--- a/drivers/spi/spi-gpio.c
+++ b/drivers/spi/spi-gpio.c
@@ -48,7 +48,7 @@ struct spi_gpio {
         struct spi_bitbang              bitbang;
         struct spi_gpio_platform_data   pdata;
         struct platform_device          *pdev;
-        int                             cs_gpios[0];
+        unsigned long                   cs_gpios[0];
 };
 
 /*----------------------------------------------------------------------*/
@@ -220,7 +220,7 @@ static u32 spi_gpio_spec_txrx_word_mode3(struct spi_device *spi,
 static void spi_gpio_chipselect(struct spi_device *spi, int is_active)
 {
         struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi);
-        unsigned int cs = spi_gpio->cs_gpios[spi->chip_select];
+        unsigned long cs = spi_gpio->cs_gpios[spi->chip_select];
 
         /* set initial clock polarity */
         if (is_active)
@@ -234,7 +234,7 @@ static void spi_gpio_chipselect(struct spi_device *spi, int is_active)
 
 static int spi_gpio_setup(struct spi_device *spi)
 {
-        unsigned int            cs;
+        unsigned long           cs;
         int                     status = 0;
         struct spi_gpio         *spi_gpio = spi_to_spi_gpio(spi);
         struct device_node      *np = spi->master->dev.of_node;
@@ -249,7 +249,7 @@ static int spi_gpio_setup(struct spi_device *spi)
                 /*
                  * ... otherwise, take it from spi->controller_data
                  */
-                cs = (unsigned int)(uintptr_t) spi->controller_data;
+                cs = (uintptr_t) spi->controller_data;
         }
 
         if (!spi->controller_state) {
@@ -277,7 +277,7 @@ static int spi_gpio_setup(struct spi_device *spi)
 static void spi_gpio_cleanup(struct spi_device *spi)
 {
         struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi);
-        unsigned int cs = spi_gpio->cs_gpios[spi->chip_select];
+        unsigned long cs = spi_gpio->cs_gpios[spi->chip_select];
 
         if (cs != SPI_GPIO_NO_CHIPSELECT)
                 gpio_free(cs);
@@ -437,7 +437,7 @@ static int spi_gpio_probe(struct platform_device *pdev)
                 return status;
 
         master = spi_alloc_master(&pdev->dev, sizeof(*spi_gpio) +
-                                        (sizeof(int) * num_devices));
+                                        (sizeof(unsigned long) * num_devices));
         if (!master) {
                 status = -ENOMEM;
                 goto gpio_free;
@@ -470,9 +470,15 @@ static int spi_gpio_probe(struct platform_device *pdev)
                 if (!SPI_N_CHIPSEL)
                         spi_gpio->cs_gpios[0] = SPI_GPIO_NO_CHIPSELECT;
                 else
-                        for (i = 0; i < SPI_N_CHIPSEL; i++)
-                                spi_gpio->cs_gpios[i] =
-                                        of_get_named_gpio(np, "cs-gpios", i);
+                        for (i = 0; i < SPI_N_CHIPSEL; i++) {
+                                status = of_get_named_gpio(np, "cs-gpios", i);
+                                if (status < 0) {
+                                        dev_err(&pdev->dev,
+                                                "invalid cs-gpios property\n");
+                                        goto gpio_free;
+                                }
+                                spi_gpio->cs_gpios[i] = status;
+                        }
         }
 #endif