1.首先查看原理图，确定按键的引脚
由上图可知，两个按键的引脚分别为：
GPIO5 1
GPIO4 14
2.修改设备树，在设备树中添加节点。
2.1进入设备树目录
/home/book/100ask_imx6ull-sdk/Linux-4.9.88/arch/arm/boot/dts
2.2打开设备树文件：
100ask_imx6ull-14x14.dts
2.3添加节点：
test_gpio_keys_100ask {compatible = "test_100ask,test_gpio_key";gpios = <&gpio5 1 GPIO_ACTIVE_HIGH&gpio4 14 GPIO_ACTIVE_HIGH>;pinctrl-names = "default";pinctrl-0 = <&key1_100ask &key2_100ask>;};
2.4编译设备树
2.5拷贝设备树文件到nfs目录下
cp arch/arm/boot/dts/100ask_imx6ull-14x14.dtb ~/nfs_rootfs/
2.6更新设备树
cp /mnt/100ask_imx6ull-14x14.dtb /boot/
3.代码
3.1完整代码
#include <linux/irqreturn.h>
#include <linux/module.h>#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/miscdevice.h>
#include <linux/kernel.h>
#include <linux/major.h>
#include <linux/mutex.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/stat.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/tty.h>
#include <linux/kmod.h>
#include <linux/gfp.h>
#include <linux/gpio/consumer.h>
#include <linux/platform_device.h>
#include <linux/of_gpio.h>
#include <linux/of_irq.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/slab.h>/* 定义结构体用来存储节点信息 */
struct gpio_key{int gpio;struct gpio_desc* gpiod;int flag;int irq;
};/* 定义全局变量来存储gpio信息 */
static struct gpio_key *gpio_keys_100ask;static irqreturn_t gpio_key_isr(int irq, void *dev_id)
{struct gpio_key *gpio_key =dev_id;int val;val = gpiod_get_value(gpio_key->gpiod);printk("key %d %d\n", gpio_key->gpio, val);return IRQ_HANDLED;
}static int gpio_key_probe(struct platform_device *pdev)
{struct device_node *node = pdev->dev.of_node;int count;int i;enum of_gpio_flags flag;int err;count = of_gpio_count(node);if (!count){printk("%s %s line %d, there isn't any gpio available\n", __FILE__, __FUNCTION__, __LINE__);return -1;}/* 分配存储按键的信息 */gpio_keys_100ask = kzalloc(sizeof(struct gpio_key) * count, GFP_KERNEL);if (!gpio_keys_100ask){printk("kzalloc error\n");return -1;}/* 初始化按键 */for(i = 0; i < count; i++){gpio_keys_100ask[i].gpio = of_get_gpio_flags(node, i, &flag);if (gpio_keys_100ask[i].gpio < 0){printk("%s %s line %d, of_get_gpio_flags fail\n", __FILE__, __FUNCTION__, __LINE__);return -1;}gpio_keys_100ask[i].gpiod = gpio_to_desc(gpio_keys_100ask[i].gpio);gpio_keys_100ask[i].irq = gpio_to_irq(gpio_keys_100ask[i].gpio);/* 申请中断 */err = request_irq(gpio_keys_100ask[i].irq, gpio_key_isr, IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING, "test_gpio_keys_100ask", &gpio_keys_100ask[i]);if (err) {printk("request_irq err\n");}}printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);return 0;
}
static int gpio_key_remove(struct platform_device *pdev)
{struct device_node *node = pdev->dev.of_node;int count;int i;count = of_gpio_count(node);printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);for(i = 0; i < count; i++){free_irq(gpio_keys_100ask[i].irq, &gpio_keys_100ask[i]);}kfree(gpio_keys_100ask);return 0;
}static const struct of_device_id gpio_key_of_match[] = {{ .compatible = "test_100ask,test_gpio_key" },{ /* sentinel */ }
};static struct platform_driver gpio_key_driver = {.driver = {.name = "test_gpio_keys_100ask",.of_match_table = gpio_key_of_match,},.probe = gpio_key_probe,.remove = gpio_key_remove,
};static int __init gpio_key_init(void)
{int ret;ret = platform_driver_register(&gpio_key_driver);if (ret){printk("platform_driver_register err\n");return -1;}printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);return 0;
}static void __exit gpio_key_exit(void)
{platform_driver_unregister(&gpio_key_driver);printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
}module_init(gpio_key_init);
module_exit(gpio_key_exit);
MODULE_LICENSE("GPL");3.2代码流程：
使用Source Insight 工具查看代码，从下往上看。3.2.1 定义驱动程序的入口和出口函数。
3.2.2在入口和出口函数中，分别注册和释放platform_driver结构体
3.2.3填充这个结构体
注意：通过gpio_key_of_match中的compatible属性和设备树中进行比较，当二者相同时，probe函数被调用。
3.2.4当二者匹配时，probe函数读取设备树的信息，得到GPIO信息，将得到的信息存储到结构体中。
3.2.5当按下按键时，中断处理函数被调用，打印信息。
4.Makefile文件
KERN_DIR = /home/book/100ask_imx6ull-sdk/Linux-4.9.88all:make -C $(KERN_DIR) M=`pwd` modulesclean:make -C $(KERN_DIR) M=`pwd` modules cleanrm -rf modules.orderobj-m += gpio_key_drv_test.o
5.实验流程：
5.1 2.6更新完设备树后，重启开发板
5.2按下按键后，屏幕有反应，表示成功了
6.重新修改的代码(逻辑一样，只是再次实现了一下)
dts
test1_gpio_keys_100ask{compatible ="test1_100ask,test1_gpio_key";gpios = <&gpio5 1 GPIO_ACTIVE_HIGH&gpio4 14 GPIO_ACTIVE_HIGH>;};
Makefile
KERN_DIR = /home/book/100ask_imx6ull-sdk/Linux-4.9.88all:make -C $(KERN_DIR) M=`pwd` modules
clean:make -C $(KERN_DIR) M=`pwd` modules cleanrm -rf modules.order
obj-m += test.o
code
#include <linux/irqreturn.h>
#include <linux/module.h>#include <linux/fs.h>
#include <linux/errno.h>
#include <linux/miscdevice.h>
#include <linux/kernel.h>
#include <linux/major.h>
#include <linux/mutex.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/stat.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/tty.h>
#include <linux/kmod.h>
#include <linux/gfp.h>
#include <linux/gpio/consumer.h>
#include <linux/platform_device.h>
#include <linux/of_gpio.h>
#include <linux/of_irq.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/slab.h>/* 定义结构体来描述gpio */
struct gpio_key{int gpio;struct gpio_desc* gpiod;int flag;int irq;
};/* 定义全局变量来存储设备树中的所有gpio节点信息 */
static struct gpio_key* gpio_keys_100ask;static irqreturn_t gpio_key_isr(int irq, void *dev_id)
{struct gpio_key* gpio_key = dev_id;int val;val = gpio_get_value(gpio_key->gpio);printk("key %d %d\n", gpio_key->gpio, val);return IRQ_HANDLED;
}static int gpio_probe(struct platform_device *pdev)
{int count, i;struct device_node *node;int err;node = pdev->dev.of_node;count = of_gpio_count(node);if (!count){printk("%s %s line %d, there isn't any gpio available\n", __FILE__, __FUNCTION__, __LINE__);return -1;}/* 申请资源 */gpio_keys_100ask = kzalloc(sizeof(struct gpio_key) * count, GFP_KERNEL);if (!gpio_keys_100ask){printk("kzalloc error\n");return -1;}/* 获得资源 */for (i = 0; i < count; i++){gpio_keys_100ask[i].gpio = of_get_gpio(node, i);if (gpio_keys_100ask[i].gpio < 0){printk("%s %s line %d, of_get_gpio_flags fail\n", __FILE__, __FUNCTION__, __LINE__);return -1;}gpio_keys_100ask[i].gpiod = gpio_to_desc(gpio_keys_100ask[i].gpio);gpio_keys_100ask[i].irq = gpio_to_irq(gpio_keys_100ask[i].gpio);/* 申请中断 */err = request_irq(gpio_keys_100ask[i].irq, gpio_key_isr, IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING, "test1_gpio_keys_100ask", &gpio_keys_100ask[i]);if (err) {printk("request_irq err\n");}}printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);return 0;
}static int gpio_remove(struct platform_device *pdev)
{int count, i;struct device_node *node;node = pdev->dev.of_node;count = of_gpio_count(node);for (i = 0; i < count; i++){free_irq(gpio_keys_100ask[i].irq, &gpio_keys_100ask[i]);}kfree(gpio_keys_100ask);printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);return 0;
}/*
* 在设备树中添加的节点的compatible属性为："test1_100ask,test1_gpio_key"
*/
static const struct of_device_id gpio_key_of_match[] = {{.compatible = "test1_100ask,test1_gpio_key"},{/* 这里必须要有一个空项，表示结束 */}
};static struct platform_driver gpio_driver = {.driver = {.name = "test1_gpio_keys_100ask",.of_match_table = gpio_key_of_match,},.probe = gpio_probe,.remove = gpio_remove,
};/* 基于platform总线来实现这个程序 */
static int gpio_init(void)
{int ret;ret = platform_driver_register(&gpio_driver);if (ret != 0){printk("platform_driver_register err\n");return -1;}printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);return ret;
}static void gpio_exit(void)
{platform_driver_unregister(&gpio_driver);printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
}module_init(gpio_init);
module_exit(gpio_exit);MODULE_LICENSE("GPL");7.文件路径
/home/book/nfs_rootfs/CSDN/01_gpio_irq/01_simple
