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-rw-r--r--include/asm-generic/gpio.h14
1 files changed, 13 insertions, 1 deletions
diff --git a/include/asm-generic/gpio.h b/include/asm-generic/gpio.h
index c7376bf80b06..8ca18e26d7e3 100644
--- a/include/asm-generic/gpio.h
+++ b/include/asm-generic/gpio.h
@@ -16,15 +16,27 @@
16 * While the GPIO programming interface defines valid GPIO numbers 16 * While the GPIO programming interface defines valid GPIO numbers
17 * to be in the range 0..MAX_INT, this library restricts them to the 17 * to be in the range 0..MAX_INT, this library restricts them to the
18 * smaller range 0..ARCH_NR_GPIOS-1. 18 * smaller range 0..ARCH_NR_GPIOS-1.
19 *
20 * ARCH_NR_GPIOS is somewhat arbitrary; it usually reflects the sum of
21 * builtin/SoC GPIOs plus a number of GPIOs on expanders; the latter is
22 * actually an estimate of a board-specific value.
19 */ 23 */
20 24
21#ifndef ARCH_NR_GPIOS 25#ifndef ARCH_NR_GPIOS
22#define ARCH_NR_GPIOS 256 26#define ARCH_NR_GPIOS 256
23#endif 27#endif
24 28
29/*
30 * "valid" GPIO numbers are nonnegative and may be passed to
31 * setup routines like gpio_request(). only some valid numbers
32 * can successfully be requested and used.
33 *
34 * Invalid GPIO numbers are useful for indicating no-such-GPIO in
35 * platform data and other tables.
36 */
37
25static inline int gpio_is_valid(int number) 38static inline int gpio_is_valid(int number)
26{ 39{
27 /* only some non-negative numbers are valid */
28 return ((unsigned)number) < ARCH_NR_GPIOS; 40 return ((unsigned)number) < ARCH_NR_GPIOS;
29} 41}
30 42