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1使用GPIO子系统编写LED灯驱动,应用程序测试
应用程序
#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <sys/ioctl.h>
#include "head.h"int main(int argc, char const *argv[])
{int a, b;int fd = open("/dev/myled0", O_RDWR);if (fd < 0){printf("打开设备文件失败\n");exit(-1);}while (1){// 从终端读取printf("请输入要实现的功能\n");printf("0(关灯) 1(开灯)\n");printf("请输入>");scanf("%d", &a);switch (a){case 1:ioctl(fd, LED_ON);break;case 0:ioctl(fd, LED_OFF);break;}}close(fd);return 0;
}
驱动程序
#include <linux/init.h>
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/io.h>
#include <linux/device.h>
#include <linux/slab.h>
#include <linux/cdev.h>
#include <linux/uaccess.h>
#include <linux/of.h>
#include <linux/of_gpio.h>
#include <linux/gpio.h>
#include "head.h"struct cdev *cdev;
char kbuf[128] = {0};
unsigned int major = 0; // 主设备号
unsigned int minor = 0; // 次设备号
dev_t devno;
struct class *cls;
struct device *dev;
// 保存解析到的设备树节点地址
struct device_node *dnode;
struct gpio_desc *gpiono1;
struct gpio_desc *gpiono2;
struct gpio_desc *gpiono3;// 封装操作方法
// 定义操作方法对象并初始化
int mycdev_open(struct inode *inode, struct file *file)
{// 获取打开文件的设备号dev_t d = inode->i_rdev;// 保存次设备号file->private_data = (void *)MINOR(d);printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);return 0;
}
ssize_t mycdev_read(struct file *file, char *ubuf, size_t size, loff_t *lof)
{printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);unsigned long ret;// 向用户空间读取拷贝if (size > sizeof(kbuf))size = sizeof(kbuf);ret = copy_to_user(ubuf, kbuf, size);if (ret) // 拷贝失败{printk("copy_to_user filed\n");return ret;}return 0;
}
ssize_t mycdev_write(struct file *file, const char *ubuf, size_t size, loff_t *lof)
{unsigned long ret;// 从用户空间读取数据if (size > sizeof(kbuf))size = sizeof(kbuf);ret = copy_from_user(kbuf, ubuf, size);if (ret) // 拷贝失败{printk("copy_to_user filed\n");return ret;}return 0;
}long mycdev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{// 获取次设备号unsigned int mon = (unsigned int)file->private_data;switch (mon){case 0:switch (cmd){case LED_ON:gpiod_set_value(gpiono1, 1);break;case LED_OFF:gpiod_set_value(gpiono1, 0);break;}break;case 1:switch (cmd){case LED_ON:gpiod_set_value(gpiono2, 1);break;case LED_OFF:gpiod_set_value(gpiono2, 0);break;}break;case 2:switch (cmd){case LED_ON:gpiod_set_value(gpiono3, 1);break;case LED_OFF:gpiod_set_value(gpiono3, 0);break;}break;}return 0;
}int mycdev_close(struct inode *inode, struct file *file)
{printk("%s:%s:%d\n", __FILE__, __func__, __LINE__);return 0;
}// 定义操作方法结构体变量并赋值
struct file_operations fops = {.open = mycdev_open,.read = mycdev_read,.write = mycdev_write,.unlocked_ioctl = mycdev_ioctl,.release = mycdev_close,
};
static int __init mycdev_init(void)
{int ret;// 1.申请字符设备驱动对象空间cdev = cdev_alloc();if (cdev == NULL){return -EFAULT;}printk("字符设备驱动对象申请成功\n");// 2.初始化字符设备驱动对象cdev_init(cdev, &fops);// 3.申请设备号if (major == 0) // 动态申请{ret = alloc_chrdev_region(&devno, minor, 3, "myled");if (ret){printk("动态申请设备号失败\n");goto A;}major = MAJOR(devno);minor = MINOR(devno);}else // 静态指定{ret = register_chrdev_region(MKDEV(major, minor), 3, "myled");if (ret){printk("静态申请设备号失败\n");goto A;}}printk("设备号申请成功\n");// 4.注册驱动ret = cdev_add(cdev, MKDEV(major, minor), 3);if (ret){printk("注册驱动失败\n");goto B;}printk("注册驱动成功\n");// 5.向上提交目录cls = class_create(THIS_MODULE, "led");if (IS_ERR(cls)){printk("向上提交目录失败\n");ret = -PTR_ERR(cls);goto C;}printk("向上提交目录成功\n");// 6.向上提交设备节点int i;for (i = 0; i < 3; i++){dev = device_create(cls, NULL, MKDEV(major, i), NULL, "myled%d", i);if (IS_ERR(dev)){printk("向上提交设备信息失败\n");ret = -PTR_ERR(dev);goto D;}}printk("向上提交设备信息成功\n");dnode = of_find_node_by_path("/leds");if (dnode == NULL){printk("解析设备树节点失败\n");return -ENXIO;}printk("解析设备树节点成功\n");gpiono1 = gpiod_get_from_of_node(dnode, "led1-gpio", 0, GPIOD_OUT_LOW, NULL);if (gpiono1 == NULL){printk("解析gpio编号失败\n");return -ENXIO;}gpiono2 = gpiod_get_from_of_node(dnode, "led2-gpio", 0, GPIOD_OUT_LOW, NULL);if (gpiono1 == NULL){printk("解析gpio编号失败\n");return -ENXIO;}gpiono3 = gpiod_get_from_of_node(dnode, "led3-gpio", 0, GPIOD_OUT_LOW, NULL);if (gpiono1 == NULL){printk("解析gpio编号失败\n");return -ENXIO;}printk("解析gpio编号成功\n");return 0;
D:// 销毁提交成功的设备信息for (--i; i >= 0; i--){device_destroy(cls, MKDEV(major, i));}// 销毁目录class_destroy(cls);
C:cdev_del(cdev);
B:unregister_chrdev_region(MKDEV(major, minor), 3);
A:kfree(cdev);return ret;
}
static void __exit mycdev_exit(void)
{gpiod_set_value(gpiono1, 0);gpiod_put(gpiono1);gpiod_set_value(gpiono2, 0);gpiod_put(gpiono2);gpiod_set_value(gpiono3, 0);gpiod_put(gpiono3);// 1.释放设备信息int i;for (i = 0; i < 3; i++){device_destroy(cls, MKDEV(major, i));}// 2.销毁目录class_destroy(cls);// 3.注销驱动对象cdev_del(cdev);// 4.释放设备号unregister_chrdev_region(MKDEV(major, minor), 3);// 5.释放对象空间kfree(cdev);}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");
2.注册三个按键的中断,只需要写内核代码
#include <linux/init.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_gpio.h>
#include <linux/gpio.h>
#include <linux/timer.h>
#include <linux/interrupt.h>
#include <linux/of_irq.h>
// 保存解析到的设备树节点地址
struct device_node *dnode;unsigned int irqno1;
unsigned int irqno2;
unsigned int irqno3;
irqreturn_t myirq_handler1(int irq, void *dev)
{printk("按下按键1\n");return IRQ_HANDLED;
}
irqreturn_t myirq_handler2(int irq, void *dev)
{printk("按下按键2\n");return IRQ_HANDLED;
}
irqreturn_t myirq_handler3(int irq, void *dev)
{printk("按下按键3\n");return IRQ_HANDLED;
}
static int __init mycdev_init(void)
{dnode = of_find_node_by_path("/myirq");if (dnode == NULL){printk("解析设备树节点失败\n");return -ENXIO;}printk("解析设备树节点成功\n");// 解析按键1的软中断号irqno1 = irq_of_parse_and_map(dnode, 0);irqno2 = irq_of_parse_and_map(dnode, 1);irqno3 = irq_of_parse_and_map(dnode, 2);if (!irqno1){printk("解析软中断号1失败\n");}if (!irqno2){printk("解析软中断号2失败\n");}if (!irqno3){printk("解析软中断号3失败\n");}printk("解析软中断号1成功irqno1=%d\n", irqno1);printk("解析软中断号2成功irqno2=%d\n", irqno2);printk("解析软中断号3成功irqno3=%d\n", irqno3);// 注册按键1中断int ret1 = request_irq(irqno1, myirq_handler1, IRQF_TRIGGER_FALLING, "key1", (void *)1);int ret2 = request_irq(irqno2, myirq_handler2, IRQF_TRIGGER_FALLING, "key2", (void *)2);int ret3 = request_irq(irqno3, myirq_handler3, IRQF_TRIGGER_FALLING, "key3", (void *)3);if (ret1){printk("按键1中断注册失败\n");}printk("按键1中断注册成功\n");if (ret2){printk("按键2中断注册失败\n");}printk("按键2中断注册成功\n");if (ret3){printk("按键3中断注册失败\n");}printk("按键3中断注册成功\n");return 0;
}
static void __exit mycdev_exit(void)
{free_irq(irqno1, (void *)1);free_irq(irqno2, (void *)2);free_irq(irqno3, (void *)3);
}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");
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