Linux中的GPIO口使用方法

Linux中的IO使用方法
应该是新版本内核才有的方法。
请参考：./Documentation/gpio.txt文件

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头文件：#include <linux/gpio.h>#include<linux/delay.h>(驱动使用延时函数mdelay)判断一个IO是否合法：int gpio_is_valid(int number);设置GPIO的方向，如果是输出同时设置电平：/* set as input or output, returning 0 or negative errno */int gpio_direction_input(unsigned gpio);int gpio_direction_output(unsigned gpio, int value);获取输入引脚的电平：/* GPIO INPUT: return zero or nonzero */int gpio_get_value(unsigned gpio);/* GPIO OUTPUT */void gpio_set_value(unsigned gpio, int value);int gpio_cansleep(unsigned gpio);To access such GPIOs, a different set of accessors is defined:/* GPIO INPUT: return zero or nonzero, might sleep */int gpio_get_value_cansleep(unsigned gpio);/* GPIO OUTPUT, might sleep */void gpio_set_value_cansleep(unsigned gpio, int value);获取一个GPIO并声明标签：/* request GPIO, returning 0 or negative errno.* non-null labels may be useful for diagnostics.*/int gpio_request(unsigned gpio, const char *label);/* release previously-claimed GPIO */void gpio_free(unsigned gpio);将GPIO映射为IRQ中断：/* map GPIO numbers to IRQ numbers */int gpio_to_irq(unsigned gpio);/* map IRQ numbers to GPIO numbers (avoid using this) */int irq_to_gpio(unsigned irq);设置GPIO IRQ中断类型：if (!sw->both_edges) {if (gpio_get_value(sw->gpio))set_irq_type(gpio_to_irq(sw->gpio), IRQ_TYPE_EDGE_FALLING);elseset_irq_type(gpio_to_irq(sw->gpio), IRQ_TYPE_EDGE_RISING);