target/linux/generic-2.6/patches-2.6.25/961-backport_gpio_define_gpio_valid.patch

   1 From: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
   2 Date: Mon, 28 Apr 2008 09:14:46 +0000 (-0700)
   3 Subject: gpio: define gpio_is_valid()
   4 X-Git-Tag: v2.6.26-rc1~849
   5 X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Ftorvalds%2Flinux-2.6.git;a=commitdiff_plain;h=e6de1808f8ebfeb7e49f3c5a30cb8f2032beb287
   6
   7 gpio: define gpio_is_valid()
   8
   9 Introduce a gpio_is_valid() predicate; use it in gpiolib.
  10
  11 Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@pengutronix.de>
  12     [ use inline function; follow the gpio_* naming convention;
  13       work without gpiolib; all programming interfaces need docs ]
  14 Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
  15 Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
  16 Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
  17 ---
  18
  19 diff --git a/Documentation/gpio.txt b/Documentation/gpio.txt
  20 index 5463009..c35ca9e 100644
  21 --- a/Documentation/gpio.txt
  22 +++ b/Documentation/gpio.txt
  23 @@ -107,6 +107,16 @@ type of GPIO controller, and on one particular board 80-95 with an FPGA.
  24  The numbers need not be contiguous; either of those platforms could also
  25  use numbers 2000-2063 to identify GPIOs in a bank of I2C GPIO expanders.
  26
  27 +If you want to initialize a structure with an invalid GPIO number, use
  28 +some negative number (perhaps "-EINVAL"); that will never be valid.  To
  29 +test if a number could reference a GPIO, you may use this predicate:
  30 +
  31 +       int gpio_is_valid(int number);
  32 +
  33 +A number that's not valid will be rejected by calls which may request
  34 +or free GPIOs (see below).  Other numbers may also be rejected; for
  35 +example, a number might be valid but unused on a given board.
  36 +
  37  Whether a platform supports multiple GPIO controllers is currently a
  38  platform-specific implementation issue.
  39
  40 diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
  41 index eb75d12..623fcd9 100644
  42 --- a/drivers/gpio/gpiolib.c
  43 +++ b/drivers/gpio/gpiolib.c
  44 @@ -99,7 +99,7 @@ int gpiochip_add(struct gpio_chip *chip)
  45          * dynamic allocation.  We don't currently support that.
  46          */
  47
  48 -       if (chip->base < 0 || (chip->base  + chip->ngpio) >= ARCH_NR_GPIOS) {
  49 +       if (chip->base < 0 || !gpio_is_valid(chip->base  + chip->ngpio)) {
  50                 status = -EINVAL;
  51                 goto fail;
  52         }
  53 @@ -174,7 +174,7 @@ int gpio_request(unsigned gpio, const char *label)
  54
  55         spin_lock_irqsave(&gpio_lock, flags);
  56
  57 -       if (gpio >= ARCH_NR_GPIOS)
  58 +       if (!gpio_is_valid(gpio))
  59                 goto done;
  60         desc = &gpio_desc[gpio];
  61         if (desc->chip == NULL)
  62 @@ -209,7 +209,7 @@ void gpio_free(unsigned gpio)
  63         unsigned long           flags;
  64         struct gpio_desc        *desc;
  65
  66 -       if (gpio >= ARCH_NR_GPIOS) {
  67 +       if (!gpio_is_valid(gpio)) {
  68                 WARN_ON(extra_checks);
  69                 return;
  70         }
  71 @@ -245,7 +245,7 @@ const char *gpiochip_is_requested(struct gpio_chip *chip, unsigned offset)
  72  {
  73         unsigned gpio = chip->base + offset;
  74
  75 -       if (gpio >= ARCH_NR_GPIOS || gpio_desc[gpio].chip != chip)
  76 +       if (!gpio_is_valid(gpio) || gpio_desc[gpio].chip != chip)
  77                 return NULL;
  78         if (test_bit(FLAG_REQUESTED, &gpio_desc[gpio].flags) == 0)
  79                 return NULL;
  80 @@ -276,7 +276,7 @@ int gpio_direction_input(unsigned gpio)
  81
  82         spin_lock_irqsave(&gpio_lock, flags);
  83
  84 -       if (gpio >= ARCH_NR_GPIOS)
  85 +       if (!gpio_is_valid(gpio))
  86                 goto fail;
  87         chip = desc->chip;
  88         if (!chip || !chip->get || !chip->direction_input)
  89 @@ -314,7 +314,7 @@ int gpio_direction_output(unsigned gpio, int value)
  90
  91         spin_lock_irqsave(&gpio_lock, flags);
  92
  93 -       if (gpio >= ARCH_NR_GPIOS)
  94 +       if (!gpio_is_valid(gpio))
  95                 goto fail;
  96         chip = desc->chip;
  97         if (!chip || !chip->set || !chip->direction_output)
  98 @@ -531,7 +531,7 @@ static int gpiolib_show(struct seq_file *s, void *unused)
  99
 100         /* REVISIT this isn't locked against gpio_chip removal ... */
 101
 102 -       for (gpio = 0; gpio < ARCH_NR_GPIOS; gpio++) {
 103 +       for (gpio = 0; gpio_is_valid(gpio); gpio++) {
 104                 if (chip == gpio_desc[gpio].chip)
 105                         continue;
 106                 chip = gpio_desc[gpio].chip;
 107 diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h
 108 index 7e77b6f..464c5b3 100644
 109 --- a/include/asm-generic/gpio.h
 110 +++ b/include/asm-generic/gpio.h
 111 @@ -16,6 +16,12 @@
 112  #define ARCH_NR_GPIOS          256
 113  #endif
 114
 115 +static inline int gpio_is_valid(int number)
 116 +{
 117 +       /* only some non-negative numbers are valid */
 118 +       return ((unsigned)number) < ARCH_NR_GPIOS;
 119 +}
 120 +
 121  struct seq_file;
 122  struct module;
 123
 124 @@ -99,6 +105,12 @@ extern int __gpio_cansleep(unsigned gpio);
 125
 126  #else
 127
 128 +static inline int gpio_is_valid(int number)
 129 +{
 130 +       /* only non-negative numbers are valid */
 131 +       return number >= 0;
 132 +}
 133 +
 134  /* platforms that don't directly support access to GPIOs through I2C, SPI,
 135   * or other blocking infrastructure can use these wrappers.
 136   */