gpio: define gpio_is_valid()
Introduce a gpio_is_valid() predicate; use it in gpiolib.
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
[ use inline function; follow the gpio_* naming convention;
work without gpiolib; all programming interfaces need docs ]
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/Documentation/gpio.txt b/Documentation/gpio.txt
index 54630095..c35ca9e 100644
--- a/Documentation/gpio.txt
+++ b/Documentation/gpio.txt
@@ -107,6 +107,16 @@
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 eb75d12e..623fcd9 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -99,7 +99,7 @@
* 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 @@
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 @@
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 @@
{
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 @@
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 @@
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 @@
/* 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 7e77b6f..464c5b3 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 @@
#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.
*/
