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113 lines
3.4 KiB
Diff
113 lines
3.4 KiB
Diff
From: Anton Vorontsov <avorontsov@ru.mvista.com>
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Date: Mon, 28 Apr 2008 09:14:47 +0000 (-0700)
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Subject: gpiochip_reserve()
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X-Git-Tag: v2.6.26-rc1~847
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X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Ftorvalds%2Flinux-2.6.git;a=commitdiff_plain;h=169b6a7a6e91e1ea32136681b475cbaf2074bf35
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gpiochip_reserve()
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Add a new function gpiochip_reserve() to reserve ranges of gpios that platform
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code has pre-allocated. That is, this marks gpio numbers which will be
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claimed by drivers that haven't yet been loaded, and thus are not available
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for dynamic gpio number allocation.
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[akpm@linux-foundation.org: remove unneeded __must_check]
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[david-b@pacbell.net: don't export gpiochip_reserve (section fix)]
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Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
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Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
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Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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---
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--- a/drivers/gpio/gpiolib.c
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+++ b/drivers/gpio/gpiolib.c
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@@ -43,6 +43,7 @@ struct gpio_desc {
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/* flag symbols are bit numbers */
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#define FLAG_REQUESTED 0
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#define FLAG_IS_OUT 1
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+#define FLAG_RESERVED 2
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#ifdef CONFIG_DEBUG_FS
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const char *label;
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@@ -88,9 +89,10 @@ static int gpiochip_find_base(int ngpio)
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int base = -ENOSPC;
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for (i = ARCH_NR_GPIOS - 1; i >= 0 ; i--) {
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- struct gpio_chip *chip = gpio_desc[i].chip;
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+ struct gpio_desc *desc = &gpio_desc[i];
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+ struct gpio_chip *chip = desc->chip;
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- if (!chip) {
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+ if (!chip && !test_bit(FLAG_RESERVED, &desc->flags)) {
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spare++;
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if (spare == ngpio) {
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base = i;
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@@ -98,7 +100,8 @@ static int gpiochip_find_base(int ngpio)
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}
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} else {
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spare = 0;
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- i -= chip->ngpio - 1;
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+ if (chip)
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+ i -= chip->ngpio - 1;
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}
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}
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@@ -108,6 +111,47 @@ static int gpiochip_find_base(int ngpio)
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}
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/**
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+ * gpiochip_reserve() - reserve range of gpios to use with platform code only
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+ * @start: starting gpio number
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+ * @ngpio: number of gpios to reserve
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+ * Context: platform init, potentially before irqs or kmalloc will work
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+ *
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+ * Returns a negative errno if any gpio within the range is already reserved
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+ * or registered, else returns zero as a success code. Use this function
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+ * to mark a range of gpios as unavailable for dynamic gpio number allocation,
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+ * for example because its driver support is not yet loaded.
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+ */
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+int __init gpiochip_reserve(int start, int ngpio)
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+{
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+ int ret = 0;
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+ unsigned long flags;
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+ int i;
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+
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+ if (!gpio_is_valid(start) || !gpio_is_valid(start + ngpio))
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+ return -EINVAL;
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+
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+ spin_lock_irqsave(&gpio_lock, flags);
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+
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+ for (i = start; i < start + ngpio; i++) {
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+ struct gpio_desc *desc = &gpio_desc[i];
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+
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+ if (desc->chip || test_bit(FLAG_RESERVED, &desc->flags)) {
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+ ret = -EBUSY;
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+ goto err;
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+ }
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+
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+ set_bit(FLAG_RESERVED, &desc->flags);
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+ }
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+
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+ pr_debug("%s: reserved gpios from %d to %d\n",
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+ __func__, start, start + ngpio - 1);
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+err:
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+ spin_unlock_irqrestore(&gpio_lock, flags);
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+
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+ return ret;
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+}
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+
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+/**
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* gpiochip_add() - register a gpio_chip
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* @chip: the chip to register, with chip->base initialized
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* Context: potentially before irqs or kmalloc will work
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--- a/include/asm-generic/gpio.h
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+++ b/include/asm-generic/gpio.h
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@@ -74,6 +74,7 @@ struct gpio_chip {
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extern const char *gpiochip_is_requested(struct gpio_chip *chip,
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unsigned offset);
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+extern int __init __must_check gpiochip_reserve(int start, int ngpio);
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/* add/remove chips */
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extern int gpiochip_add(struct gpio_chip *chip);
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