rename target/linux/generic-2.6 to generic

[openwrt.git] / target / linux / generic / patches-2.6.25 / 962-backport_gpiolib_dynamic_gpio_number_allocation.patch

diff --git a/target/linux/generic/patches-2.6.25/962-backport_gpiolib_dynamic_gpio_number_allocation.patch b/target/linux/generic/patches-2.6.25/962-backport_gpiolib_dynamic_gpio_number_allocation.patch
new file mode 100644 (file)
index 0000000..0960f67
--- /dev/null
+++ b/target/linux/generic/patches-2.6.25/962-backport_gpiolib_dynamic_gpio_number_allocation.patch
@@ -0,0 +1,116 @@
+From: Anton Vorontsov <avorontsov@ru.mvista.com>
+Date: Mon, 28 Apr 2008 09:14:46 +0000 (-0700)
+Subject: gpiolib: dynamic gpio number allocation
+X-Git-Tag: v2.6.26-rc1~848
+X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Ftorvalds%2Flinux-2.6.git;a=commitdiff_plain;h=8d0aab2f16c4fa170f32e7a74a52cd0122bbafef
+
+gpiolib: dynamic gpio number allocation
+
+If gpio_chip->base is negative during registration, gpiolib performs dynamic
+base allocation.  This is useful for devices that aren't always present, such
+as GPIOs on hotplugged devices rather than mainboards.  (This behavior was
+previously specified but not implemented.)
+
+To avoid using any numbers that may have been explicitly assigned but not yet
+registered, this dynamic allocation assigns GPIO numbers from the biggest
+number on down, instead of from the smallest on up.
+
+Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
+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>
+---
+
+--- a/drivers/gpio/gpiolib.c
++++ b/drivers/gpio/gpiolib.c
+@@ -80,6 +80,33 @@ static inline struct gpio_chip *gpio_to_
+       return gpio_desc[gpio].chip;
+ }
+ 
++/* dynamic allocation of GPIOs, e.g. on a hotplugged device */
++static int gpiochip_find_base(int ngpio)
++{
++      int i;
++      int spare = 0;
++      int base = -ENOSPC;
++
++      for (i = ARCH_NR_GPIOS - 1; i >= 0 ; i--) {
++              struct gpio_chip *chip = gpio_desc[i].chip;
++
++              if (!chip) {
++                      spare++;
++                      if (spare == ngpio) {
++                              base = i;
++                              break;
++                      }
++              } else {
++                      spare = 0;
++                      i -= chip->ngpio - 1;
++              }
++      }
++
++      if (gpio_is_valid(base))
++              pr_debug("%s: found new base at %d\n", __func__, base);
++      return base;
++}
++
+ /**
+  * gpiochip_add() - register a gpio_chip
+  * @chip: the chip to register, with chip->base initialized
+@@ -88,38 +115,49 @@ static inline struct gpio_chip *gpio_to_
+  * Returns a negative errno if the chip can't be registered, such as
+  * because the chip->base is invalid or already associated with a
+  * different chip.  Otherwise it returns zero as a success code.
++ *
++ * If chip->base is negative, this requests dynamic assignment of
++ * a range of valid GPIOs.
+  */
+ int gpiochip_add(struct gpio_chip *chip)
+ {
+       unsigned long   flags;
+       int             status = 0;
+       unsigned        id;
++      int             base = chip->base;
+ 
+-      /* NOTE chip->base negative is reserved to mean a request for
+-       * dynamic allocation.  We don't currently support that.
+-       */
+-
+-      if (chip->base < 0 || !gpio_is_valid(chip->base  + chip->ngpio)) {
++      if ((!gpio_is_valid(base) || !gpio_is_valid(base + chip->ngpio))
++                      && base >= 0) {
+               status = -EINVAL;
+               goto fail;
+       }
+ 
+       spin_lock_irqsave(&gpio_lock, flags);
+ 
++      if (base < 0) {
++              base = gpiochip_find_base(chip->ngpio);
++              if (base < 0) {
++                      status = base;
++                      goto fail_unlock;
++              }
++              chip->base = base;
++      }
++
+       /* these GPIO numbers must not be managed by another gpio_chip */
+-      for (id = chip->base; id < chip->base + chip->ngpio; id++) {
++      for (id = base; id < base + chip->ngpio; id++) {
+               if (gpio_desc[id].chip != NULL) {
+                       status = -EBUSY;
+                       break;
+               }
+       }
+       if (status == 0) {
+-              for (id = chip->base; id < chip->base + chip->ngpio; id++) {
++              for (id = base; id < base + chip->ngpio; id++) {
+                       gpio_desc[id].chip = chip;
+                       gpio_desc[id].flags = 0;
+               }
+       }
+ 
++fail_unlock:
+       spin_unlock_irqrestore(&gpio_lock, flags);
+ fail:
+       /* failures here can mean systems won't boot... */