From: Anton Vorontsov Date: Mon, 28 Apr 2008 09:14:47 +0000 (-0700) Subject: gpiochip_reserve() X-Git-Tag: v2.6.26-rc1~847 X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Ftorvalds%2Flinux-2.6.git;a=commitdiff_plain;h=169b6a7a6e91e1ea32136681b475cbaf2074bf35 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: Anton Vorontsov Signed-off-by: David Brownell Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -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; } } @@ -108,6 +111,47 @@ static int gpiochip_find_base(int ngpio) } /** + * 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 * Context: potentially before irqs or kmalloc will work --- a/include/asm-generic/gpio.h +++ b/include/asm-generic/gpio.h @@ -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);