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Message-Id: <200802101622.20913.david-b@pacbell.net>
Date: Sun, 10 Feb 2008 16:22:20 -0800
From: David Brownell <david-b@...bell.net>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: lkml <linux-kernel@...r.kernel.org>,
Guennadi Liakhovetski <g.liakhovetski@...gutronix.de>
Subject: [patch 2.6.25-rc1 3/3] gpio: define gpio_is_valid()
From: Guennadi Liakhovetski <g.liakhovetski@...gutronix.de>
Introduce a gpio_is_valid() predicate; use it in gpiolib.
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@...gutronix.de>
[ use inline function; follow the gpio_* naming convention;
work without gpiolib; all programming interfaces need docs ]
Signed-off-by: David Brownell <dbrownell@...rs.sourceforge.net>
---
Documentation/gpio.txt | 10 ++++++++++
drivers/gpio/gpiolib.c | 14 +++++++-------
include/asm-generic/gpio.h | 12 ++++++++++++
3 files changed, 29 insertions(+), 7 deletions(-)
--- g26.orig/Documentation/gpio.txt 2008-02-10 16:06:30.000000000 -0800
+++ g26/Documentation/gpio.txt 2008-02-10 16:09:54.000000000 -0800
@@ -102,6 +102,16 @@ type of GPIO controller, and on one part
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.
--- g26.orig/drivers/gpio/gpiolib.c 2008-02-10 16:09:51.000000000 -0800
+++ g26/drivers/gpio/gpiolib.c 2008-02-10 16:09:54.000000000 -0800
@@ -96,7 +96,7 @@ 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;
}
@@ -171,7 +171,7 @@ int gpio_request(unsigned gpio, const ch
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)
@@ -206,7 +206,7 @@ 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;
}
@@ -242,7 +242,7 @@ const char *gpiochip_is_requested(struct
{
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;
@@ -273,7 +273,7 @@ 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)
@@ -311,7 +311,7 @@ int gpio_direction_output(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->set || !chip->direction_output)
@@ -528,7 +528,7 @@ static int gpiolib_show(struct seq_file
/* 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;
--- g26.orig/include/asm-generic/gpio.h 2008-02-10 16:09:51.000000000 -0800
+++ g26/include/asm-generic/gpio.h 2008-02-10 16:09:54.000000000 -0800
@@ -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.
*/
--
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