http://blog.csdn.net/morixinguan/article/details/77808088
上節，我們明白了proc文件系統的作用，接下來我們在友善之臂已經寫好的led驅動的基礎上，在proc目錄下創建一個文件夾，然后加入led驅動的版本信息讀取。
我們在init函數的最后加入:
//定義proc文件系統節點
struct proc_dir_entry *dev_dir , *dev_version;
//創建一個目錄
dev_dir = proc_mkdir("Tiny4412_leds", NULL);
//創建一個文件
dev_version = create_proc_entry("version", S_IRUGO, dev_dir);
//調用讀版本的函數
dev_version->read_proc = proc_read_version ;#define VERSION_LEN 20
char Tiny4412_LED_version[VERSION_LEN] = "20170908\n";
int proc_read_version(char *page, char **start, off_t off, int count, int *eof, void *data)
{int len ; len = sprintf(page,Tiny4412_LED_version); //將字符串寫入page,相當于copy到用戶層return len ;
}接下來編譯完成，將kenel刷入開發板后卡機，用adb shell進入可以看到如下：
修改的源碼：
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/miscdevice.h>
#include <linux/fs.h>
#include <linux/types.h>
#include <linux/moduleparam.h>
#include <linux/slab.h>
#include <linux/ioctl.h>
#include <linux/cdev.h>
#include <linux/delay.h>#include <linux/gpio.h>
#include <mach/gpio.h>
#include <plat/gpio-cfg.h>//添加必要的頭文件
#include <linux/proc_fs.h>
#include <linux/uaccess.h>#define DEVICE_NAME "leds"static int led_gpios[] = {EXYNOS4212_GPM4(0),EXYNOS4212_GPM4(1),EXYNOS4212_GPM4(2),EXYNOS4212_GPM4(3),
};#define LED_NUM ARRAY_SIZE(led_gpios)static long tiny4412_leds_ioctl(struct file *filp, unsigned int cmd,unsigned long arg)
{switch(cmd) {case 0:case 1:if (arg > LED_NUM) {return -EINVAL;}gpio_set_value(led_gpios[arg], !cmd);//printk(DEVICE_NAME": %d %d\n", arg, cmd);break;default:return -EINVAL;}return 0;
}static struct file_operations tiny4412_led_dev_fops = {.owner = THIS_MODULE,.unlocked_ioctl = tiny4412_leds_ioctl,
};static struct miscdevice tiny4412_led_dev = {.minor = MISC_DYNAMIC_MINOR,.name = DEVICE_NAME,.fops = &tiny4412_led_dev_fops,
};#define VERSION_LEN 20
char Tiny4412_LED_version[VERSION_LEN] = "20170908\n";
int proc_read_version(char *page, char **start, off_t off, int count, int *eof, void *data)
{int len ; len = sprintf(page,Tiny4412_LED_version);return len ;
}static int __init tiny4412_led_dev_init(void) {int ret;int i;for (i = 0; i < LED_NUM; i++) {ret = gpio_request(led_gpios[i], "LED");if (ret) {printk("%s: request GPIO %d for LED failed, ret = %d\n", DEVICE_NAME,led_gpios[i], ret);return ret;}s3c_gpio_cfgpin(led_gpios[i], S3C_GPIO_OUTPUT);gpio_set_value(led_gpios[i], 1);}//雜類設備ret = misc_register(&tiny4412_led_dev);//定義proc文件系統節點struct proc_dir_entry *dev_dir , *dev_version;//創建一個目錄dev_dir = proc_mkdir("Tiny4412_leds", NULL); //創建一個文件dev_version = create_proc_entry("version", S_IRUGO, dev_dir); //調用讀版本的函數dev_version->read_proc = proc_read_version ;printk(DEVICE_NAME"\tinitialized\n");return ret;
}static void __exit tiny4412_led_dev_exit(void) {int i;for (i = 0; i < LED_NUM; i++) {gpio_free(led_gpios[i]);}misc_deregister(&tiny4412_led_dev);
}module_init(tiny4412_led_dev_init);
module_exit(tiny4412_led_dev_exit);MODULE_LICENSE("GPL");
MODULE_AUTHOR("FriendlyARM Inc & Y.X.YANG modify");
