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author | Ingo Molnar <mingo@elte.hu> | 2010-10-07 09:43:11 +0200 |
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committer | Ingo Molnar <mingo@elte.hu> | 2010-10-07 09:43:11 +0200 |
commit | d4f8f217b8a5d5bd02af979650418dca4caec472 (patch) | |
tree | af047bfa9729c975e24cb7624107574e884d3a57 /include/asm-generic/gpio.h | |
parent | 2dfbf4dfbe47a484bae20456c12b40763b9b6af7 (diff) | |
parent | 773e3f93577ffb493fb7c39b1a6ecf39b5748e87 (diff) | |
download | kernel_samsung_smdk4412-d4f8f217b8a5d5bd02af979650418dca4caec472.zip kernel_samsung_smdk4412-d4f8f217b8a5d5bd02af979650418dca4caec472.tar.gz kernel_samsung_smdk4412-d4f8f217b8a5d5bd02af979650418dca4caec472.tar.bz2 |
Merge branch 'rcu/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-2.6-rcu into core/rcu
Diffstat (limited to 'include/asm-generic/gpio.h')
-rw-r--r-- | include/asm-generic/gpio.h | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h index c7376bf..8ca18e2 100644 --- a/include/asm-generic/gpio.h +++ b/include/asm-generic/gpio.h @@ -16,15 +16,27 @@ * While the GPIO programming interface defines valid GPIO numbers * to be in the range 0..MAX_INT, this library restricts them to the * smaller range 0..ARCH_NR_GPIOS-1. + * + * ARCH_NR_GPIOS is somewhat arbitrary; it usually reflects the sum of + * builtin/SoC GPIOs plus a number of GPIOs on expanders; the latter is + * actually an estimate of a board-specific value. */ #ifndef ARCH_NR_GPIOS #define ARCH_NR_GPIOS 256 #endif +/* + * "valid" GPIO numbers are nonnegative and may be passed to + * setup routines like gpio_request(). only some valid numbers + * can successfully be requested and used. + * + * Invalid GPIO numbers are useful for indicating no-such-GPIO in + * platform data and other tables. + */ + static inline int gpio_is_valid(int number) { - /* only some non-negative numbers are valid */ return ((unsigned)number) < ARCH_NR_GPIOS; } |