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>

diff --git a/drivers/gpio/gpio-mcp23s08.c b/drivers/gpio/gpio-mcp23s08.c
index 99a6831..3d53fd6 100644 (file)
--- 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)