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Commit 169b6a7a authored by Anton Vorontsov's avatar Anton Vorontsov Committed by Linus Torvalds
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gpiochip_reserve() 



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: default avatarAnton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: default avatarDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 8d0aab2f

drivers/gpio/gpiolib.c

+47 −3
Original line number Diff line number Diff line
@@ -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;
@@ -98,6 +100,7 @@ static int gpiochip_find_base(int ngpio) 
			}

		} else {

			spare = 0;

			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

include/asm-generic/gpio.h

+1 −0
Original line number Diff line number Diff line
@@ -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);