gpio: mcp23s08: Bug fix of SPI device tree registration.

The chips variable needs to be incremented for each chip that is
found in the spi_present_mask when registering via device tree.
Without this and the checking a negative index is passed to the
data->chip array in a subsequent loop.

Cc: stable@vger.kernel.org
Signed-off-by: Michael Welling <mwelling@ieee.org>
Acked-by: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 7 insertions, 5 deletions

diff --git a/drivers/gpio/gpio-mcp23s08.c b/drivers/gpio/gpio-mcp23s08.c
index 99a68310e7c0..3d53fd6880d1 100644
--- a/drivers/gpio/gpio-mcp23s08.c
+++ b/drivers/gpio/gpio-mcp23s08.c
@@ -894,9 +894,11 @@ static int mcp23s08_probe(struct spi_device *spi)
                         dev_err(&spi->dev, "invalid spi-present-mask\n");
                         return -ENODEV;
                 }
-
-                for (addr = 0; addr < ARRAY_SIZE(pdata->chip); addr++)
+                for (addr = 0; addr < ARRAY_SIZE(pdata->chip); addr++) {
+                        if ((spi_present_mask & (1 << addr)))
+                                chips++;
                         pullups[addr] = 0;
+                }
         } else {
                 type = spi_get_device_id(spi)->driver_data;
                 pdata = dev_get_platdata(&spi->dev);
@@ -919,12 +921,12 @@ static int mcp23s08_probe(struct spi_device *spi)
                         pullups[addr] = pdata->chip[addr].pullups;
                 }
 
-                if (!chips)
-                        return -ENODEV;
-
                 base = pdata->base;
         }
 
+        if (!chips)
+                return -ENODEV;
+
         data = kzalloc(sizeof(*data) + chips * sizeof(struct mcp23s08),
                         GFP_KERNEL);
         if (!data)