linux驱动----驱动程序

设备驱动程序

设备驱动开发流程

设备操作方法的编写

（open/read/write/ioctl/close）

static int open(struct inode* node, struct file* file) 45 { 46 led_init(); 47 printk("led open...\n"); 48 return 0; 49 } 50 51 static ssize_t read(struct file* file, char __user* buf, size_t len, loff_t* offset) 52 { 53 // copy_to_user(); 54 printk("led read...\n"); 55 return 0; 56 } 57 58 static ssize_t write(struct file* file, const char __user* buf, size_t len, loff_t* offset) 59 { 60 // "ledon" on "ledoff" off 61 unsigned char data[10] = {0}; 62 size_t len_cp = len < sizeof(data) ? len : sizeof data; 63 int size_cp = copy_from_user(data, buf, len_cp); 64 if (size_cp < 0) 65 return size_cp; 66 67 if (!strcmp(buf, "ledon")) 68 led_on(); 69 else if (!(strcmp(buf, "ledoff"))) 70 led_off(); 71 else 72 return -EINVAL; 73 74 printk("led write...\n"); 75 76 return size_cp; 77 } static int close(struct inode* node, struct file* file) 80 { 81 led_off(); 82 printk("led close...\n"); 83 return 0; 84 }

设备号的编写以及创建设备节点

开机启动函数中：

int ret = 0; 103 //dev = MKDEV(MAJOR_NUM, MINOR_NUM); //(MAJOR_NUM << 20) | MINOR_NUM; 104 ret = alloc_chrdev_region(&dev,0,1,"led_driver"); 105 if(ret < 0) 106 goto err_alloc; 107 108 cdev_init(&cdev, &fops); 109 ret = cdev_add(&cdev, dev, 1); 110 if (ret < 0) 111 goto err_cdev; 112 113 #if 0 114 ret = register_chrdev_region(dev, 1, DEV_NAME); 115 if (ret < 0) 116 goto err_register_chrdev; 117 #endif 118 119 cls = class_create(THIS_MODULE,"led_class"); 120 if(IS_ERR(cls)) 121 { 122 ret = PTR_ERR(cls); 123 printk(KERN_ERR "class_create failed! ret = %d\n",ret); 124 goto err_class; 125 } 126 Dev = device_create(cls,NULL,dev,NULL,"led"); 127 if(IS_ERR(Dev)) 128 { 129 ret = PTR_ERR(Dev); 130 printk(KERN_ERR "device_create failed! ret = %d\n",ret); 131 goto err_device; 132 }

卸载清理函数中：

static void __exit led1_exit(void) 159 { 160 161 device_destroy(led_class, dev); // 销毁设备 162 class_destroy(led_class); // 销毁类 163 164 iounmap(gpio1_gdir); 165 iounmap(gpio1_dr); 166 iounmap(sw_pad); 167 iounmap(sw_mux); 168 169 unregister_chrdev_region(dev, 1); 170 cdev_del(&cdev); 171 172 printk("led_exit ##############\n"); 173 }

总的代码

#include <asm/io.h> #include <asm/string.h> #include <asm/uaccess.h> #include <linux/cdev.h> #include <linux/export.h> #include <linux/fs.h> #include <linux/init.h> #include <linux/kdev_t.h> #include <linux/printk.h> #include <linux/types.h> #include <linux/device.h> #define MAJOR_NUM 247 #define MINOR_NUM 0 #define DEV_NAME "led" #define IOMUXC_SW_MUX_CTL_PAD_GPIO1_IO03 0x20e0068U #define IOMUXC_SW_PAD_CTL_PAD_GPIO1_IO03 0x20E02F4U #define GPIO1_DR 0x209C000U #define GPIO1_GDIR 0x209C004U static volatile unsigned int* sw_mux; static volatile unsigned int* sw_pad; static volatile unsigned int* gpio1_dr; static volatile unsigned int* gpio1_gdir; static void led_init(void) { *sw_mux = 0x05; *sw_pad = 0x10b0; *gpio1_gdir |= (1 << 3); *gpio1_dr |= (1 << 3); } static void led_on(void) { *gpio1_dr &= ~(1 << 3); } static void led_off(void) { *gpio1_dr |= (1 << 3); } static int open(struct inode* node, struct file* file) { led_init(); printk("led open...\n"); return 0; } static ssize_t read(struct file* file, char __user* buf, size_t len, loff_t* offset) { // copy_to_user(); printk("led read...\n"); return 0; } static ssize_t write(struct file* file, const char __user* buf, size_t len, loff_t* offset) { // "ledon" on "ledoff" off unsigned char data[10] = {0}; size_t len_cp = len < sizeof(data) ? len : sizeof data; int size_cp = copy_from_user(data, buf, len_cp); if (size_cp < 0) return size_cp; if (!strcmp(buf, "ledon")) led_on(); else if (!(strcmp(buf, "ledoff"))) led_off(); else return -EINVAL; printk("led write...\n"); return size_cp; } static int close(struct inode* node, struct file* file) { led_off(); printk("led close...\n"); return 0; } static dev_t dev; static struct file_operations fops = { .owner = THIS_MODULE, .open = open, .read = read, .write = write, .release = close }; static struct cdev cdev; static struct class *cls; static struct device *Dev; static int __init led1_init(void) { int ret = 0; //dev = MKDEV(MAJOR_NUM, MINOR_NUM); //(MAJOR_NUM << 20) | MINOR_NUM; ret = alloc_chrdev_region(&dev,0,1,"led_driver"); if(ret < 0) goto err_alloc; cdev_init(&cdev, &fops); ret = cdev_add(&cdev, dev, 1); if (ret < 0) goto err_cdev; #if 0 ret = register_chrdev_region(dev, 1, DEV_NAME); if (ret < 0) goto err_register_chrdev; #endif cls = class_create(THIS_MODULE,"led_class"); if(IS_ERR(cls)) { ret = PTR_ERR(cls); printk(KERN_ERR "class_create failed! ret = %d\n",ret); goto err_class; } Dev = device_create(cls,NULL,dev,NULL,"led"); if(IS_ERR(Dev)) { ret = PTR_ERR(Dev); printk(KERN_ERR "device_create failed! ret = %d\n",ret); goto err_device; } sw_mux = ioremap(IOMUXC_SW_MUX_CTL_PAD_GPIO1_IO03, 4); sw_pad = ioremap(IOMUXC_SW_PAD_CTL_PAD_GPIO1_IO03, 4); gpio1_dr = ioremap(GPIO1_DR, 4); gpio1_gdir = ioremap(GPIO1_GDIR, 4); printk("led_init ##############\n"); return 0; #if 0 err_register_chrdev: unregister_chrdev_region(dev, 1); #endif err_device: class_destroy(cls); err_class: err_cdev: cdev_del(&cdev); err_alloc: printk("led_init failed ############## ret = %d\n", ret); return ret; } static void __exit led1_exit(void) { iounmap(gpio1_gdir); iounmap(gpio1_dr); iounmap(sw_pad); iounmap(sw_mux); unregister_chrdev_region(dev, 1); cdev_del(&cdev); printk("led_exit ##############\n"); } module_init(led1_init); module_exit(led1_exit);