Android为Tiny4412设备驱动在proc目录下添加一个可读版本信息的文件

//定义proc文件系统节点
struct proc_dir_entry *dev_dir , *dev_version;
//创建一个目录
dev_dir = proc_mkdir("Tiny4412_leds", NULL); 
//创建一个文件
dev_version = create_proc_entry("version", S_IRUGO, dev_dir); 
//调用读版本的函数
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); //将字符串写入page,相当于copy到用户层
 return len ;
}

#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>
//添加必要的头文件
#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);
 }
 //杂类设备
 ret = misc_register(&tiny4412_led_dev);
 //定义proc文件系统节点
 struct proc_dir_entry *dev_dir , *dev_version;
 //创建一个目录
 dev_dir = proc_mkdir("Tiny4412_leds", NULL); 
 //创建一个文件
 dev_version = create_proc_entry("version", S_IRUGO, dev_dir); 
 //调用读版本的函数
 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");