diff options
| -rw-r--r-- | Documentation/gpio.txt | 10 | ||||
| -rw-r--r-- | drivers/gpio/gpiolib.c | 14 | ||||
| -rw-r--r-- | include/asm-generic/gpio.h | 12 |
3 files changed, 29 insertions, 7 deletions
diff --git a/Documentation/gpio.txt b/Documentation/gpio.txt index 54630095aa3..c35ca9e40d4 100644 --- a/Documentation/gpio.txt +++ b/Documentation/gpio.txt @@ -107,6 +107,16 @@ type of GPIO controller, and on one particular board 80-95 with an FPGA. The numbers need not be contiguous; either of those platforms could also use numbers 2000-2063 to identify GPIOs in a bank of I2C GPIO expanders. +If you want to initialize a structure with an invalid GPIO number, use +some negative number (perhaps "-EINVAL"); that will never be valid. To +test if a number could reference a GPIO, you may use this predicate: + + int gpio_is_valid(int number); + +A number that's not valid will be rejected by calls which may request +or free GPIOs (see below). Other numbers may also be rejected; for +example, a number might be valid but unused on a given board. + Whether a platform supports multiple GPIO controllers is currently a platform-specific implementation issue. diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index eb75d12e83b..623fcd9b547 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -99,7 +99,7 @@ int gpiochip_add(struct gpio_chip *chip) * dynamic allocation. We don't currently support that. */ - if (chip->base < 0 || (chip->base + chip->ngpio) >= ARCH_NR_GPIOS) { + if (chip->base < 0 || !gpio_is_valid(chip->base + chip->ngpio)) { status = -EINVAL; goto fail; } @@ -174,7 +174,7 @@ int gpio_request(unsigned gpio, const char *label) spin_lock_irqsave(&gpio_lock, flags); - if (gpio >= ARCH_NR_GPIOS) + if (!gpio_is_valid(gpio)) goto done; desc = &gpio_desc[gpio]; if (desc->chip == NULL) @@ -209,7 +209,7 @@ void gpio_free(unsigned gpio) unsigned long flags; struct gpio_desc *desc; - if (gpio >= ARCH_NR_GPIOS) { + if (!gpio_is_valid(gpio)) { WARN_ON(extra_checks); return; } @@ -245,7 +245,7 @@ const char *gpiochip_is_requested(struct gpio_chip *chip, unsigned offset) { unsigned gpio = chip->base + offset; - if (gpio >= ARCH_NR_GPIOS || gpio_desc[gpio].chip != chip) + if (!gpio_is_valid(gpio) || gpio_desc[gpio].chip != chip) return NULL; if (test_bit(FLAG_REQUESTED, &gpio_desc[gpio].flags) == 0) return NULL; @@ -276,7 +276,7 @@ int gpio_direction_input(unsigned gpio) spin_lock_irqsave(&gpio_lock, flags); - if (gpio >= ARCH_NR_GPIOS) + if (!gpio_is_valid(gpio)) goto fail; chip = desc->chip; if (!chip || !chip->get || !chip->direction_input) @@ -314,7 +314,7 @@ int gpio_direction_output(unsigned gpio, int value) spin_lock_irqsave(&gpio_lock, flags); - if (gpio >= ARCH_NR_GPIOS) + if (!gpio_is_valid(gpio)) goto fail; chip = desc->chip; if (!chip || !chip->set || !chip->direction_output) @@ -531,7 +531,7 @@ static int gpiolib_show(struct seq_file *s, void *unused) /* REVISIT this isn't locked against gpio_chip removal ... */ - for (gpio = 0; gpio < ARCH_NR_GPIOS; gpio++) { + for (gpio = 0; gpio_is_valid(gpio); gpio++) { if (chip == gpio_desc[gpio].chip) continue; chip = gpio_desc[gpio].chip; diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h index 7e77b6ff45b..464c5b334dc 100644 --- a/include/asm-generic/gpio.h +++ b/include/asm-generic/gpio.h @@ -16,6 +16,12 @@ #define ARCH_NR_GPIOS 256 #endif +static inline int gpio_is_valid(int number) +{ + /* only some non-negative numbers are valid */ + return ((unsigned)number) < ARCH_NR_GPIOS; +} + struct seq_file; struct module; @@ -99,6 +105,12 @@ extern int __gpio_cansleep(unsigned gpio); #else +static inline int gpio_is_valid(int number) +{ + /* only non-negative numbers are valid */ + return number >= 0; +} + /* platforms that don't directly support access to GPIOs through I2C, SPI, * or other blocking infrastructure can use these wrappers. */ |