gpiolib: do not allow to insert an empty gpiochip

We need to check if number of gpio is positive if there is no
such check in devicetree or acpi or whatever called before
gpiochip_add.

I suppose that devicetree and acpi do not allow insert gpiochip
with zero number but I do not know if it is enough to ignore
this check in gpiochip_add.

Signed-off-by: Bamvor Jian Zhang <bamvor.zhangjian@linaro.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index eed70c36e8ac6eb266eefe85a1b72d1a0e02ca4c..89e01538e40ee845176460539551f2992b05eece 100644 (file)
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -325,6 +325,11 @@ int gpiochip_add(struct gpio_chip *chip)
        if (!descs)
                return -ENOMEM;
 
+       if (chip->ngpio == 0) {
+               chip_err(chip, "tried to insert a GPIO chip with zero lines\n");
+               return -EINVAL;
+       }
+
        spin_lock_irqsave(&gpio_lock, flags);
 
        if (base < 0) {