Messages in this thread Patch in this message | | | Date | Tue, 11 Mar 2008 20:41:18 +0300 | From | Anton Vorontsov <> | Subject | [PATCH 2/3] gpiolib: implement gpiochip_reserve |
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Function gpiochip_reserve() reserves range of gpios to use with platform code only, that is, this function used to mark specified range of gpios unavailable for the dynamic gpio base allocator.
Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com> --- drivers/gpio/gpiolib.c | 51 +++++++++++++++++++++++++++++++++++++++++-- include/asm-generic/gpio.h | 1 + 2 files changed, 49 insertions(+), 3 deletions(-)
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 81d81c9..2149e0c 100644 --- 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; @@ -80,6 +81,48 @@ static inline struct gpio_chip *gpio_to_chip(unsigned gpio) return gpio_desc[gpio].chip; } +/** + * gpiochip_reserve() - reserve range of gpios to use with platform code only + * @start: starting gpio number + * @ngpio: number of gpios to reserve + * Context: potentially before irqs or kmalloc will work + * + * Returns a negative errno if any gpio within the range already reserved + * or registered. Otherwise it returns zero as a success code. + * Use this function to mark specified range of gpios unavailable for the + * dynamic gpio base allocator. + */ +int __must_check 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; +} +EXPORT_SYMBOL_GPL(gpiochip_reserve); + static int gpiochip_find_base(int ngpio) { int i; @@ -87,9 +130,10 @@ 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; @@ -97,7 +141,8 @@ static int gpiochip_find_base(int ngpio) } } else { spare = 0; - i -= chip->ngpio - 1; + if (chip) + i -= chip->ngpio - 1; } } diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h index 464c5b3..20f5d67 100644 --- 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 __must_check gpiochip_reserve(int start, int ngpio); /* add/remove chips */ extern int gpiochip_add(struct gpio_chip *chip); -- 1.5.2.2
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