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gpiochip_reserve()

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Add a new function gpiochip_reserve() to reserve ranges of gpios that platform
code has pre-allocated.  That is, this marks gpio numbers which will be
claimed by drivers that haven't yet been loaded, and thus are not available
for dynamic gpio number allocation.

[akpm@linux-foundation.org: remove unneeded __must_check]
[david-b@pacbell.net: don't export gpiochip_reserve (section fix)]
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>
This commit is contained in:
Anton Vorontsov 2008-04-28 02:14:47 -07:00 committed by Linus Torvalds
parent 8d0aab2f16
commit 169b6a7a6e
2 changed files with 48 additions and 3 deletions
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50
drivers/gpio/gpiolib.c
View File

@ -43,6 +43,7 @@ struct gpio_desc {
/* flag symbols are bit numbers */
#define FLAG_REQUESTED 0
#define FLAG_IS_OUT 1
#define FLAG_RESERVED 2
#ifdef CONFIG_DEBUG_FS
const char *label;
@ -88,9 +89,10 @@ static int gpiochip_find_base(int ngpio)
int base = -ENOSPC;
for (i = ARCH_NR_GPIOS - 1; i >= 0 ; i--) {
struct gpio_chip *chip = gpio_desc[i].chip;
struct gpio_desc *desc = &gpio_desc[i];
struct gpio_chip *chip = desc->chip;
if (!chip) {
if (!chip && !test_bit(FLAG_RESERVED, &desc->flags)) {
spare++;
if (spare == ngpio) {
base = i;
@ -98,7 +100,8 @@ static int gpiochip_find_base(int ngpio)
}
} else {
spare = 0;
i -= chip->ngpio - 1;
if (chip)
i -= chip->ngpio - 1;
}
}
@ -107,6 +110,47 @@ static int gpiochip_find_base(int ngpio)
return base;
}
/**
* gpiochip_reserve() - reserve range of gpios to use with platform code only
* @start: starting gpio number
* @ngpio: number of gpios to reserve
* Context: platform init, potentially before irqs or kmalloc will work
*
* Returns a negative errno if any gpio within the range is already reserved
* or registered, else returns zero as a success code. Use this function
* to mark a range of gpios as unavailable for dynamic gpio number allocation,
* for example because its driver support is not yet loaded.
*/
int __init gpiochip_reserve(int start, int ngpio)
{
int ret = 0;
unsigned long flags;
int i;
if (!gpio_is_valid(start) || !gpio_is_valid(start + ngpio))
return -EINVAL;
spin_lock_irqsave(&gpio_lock, flags);
for (i = start; i < start + ngpio; i++) {
struct gpio_desc *desc = &gpio_desc[i];
if (desc->chip || test_bit(FLAG_RESERVED, &desc->flags)) {
ret = -EBUSY;
goto err;
}
set_bit(FLAG_RESERVED, &desc->flags);
}
pr_debug("%s: reserved gpios from %d to %d\n",
__func__, start, start + ngpio - 1);
err:
spin_unlock_irqrestore(&gpio_lock, flags);
return ret;
}
/**
* gpiochip_add() - register a gpio_chip
* @chip: the chip to register, with chip->base initialized

1
include/asm-generic/gpio.h
View File

@ -74,6 +74,7 @@ struct gpio_chip {
extern const char *gpiochip_is_requested(struct gpio_chip *chip,
unsigned offset);
extern int __init __must_check gpiochip_reserve(int start, int ngpio);
/* add/remove chips */
extern int gpiochip_add(struct gpio_chip *chip);