读不到内核数据，请各位看看啥原因

lilysulia 发表于 2011-01-21 15:55

小弟刚接触驱动，写了个程序结果内核数据却无法读出请给位看一下问题出在那谢谢！
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>

#define DEVICE_NAME "/dev/key_test_by_atmel"

int main()
{
int fd;
   int i;
int buf;

fd = open(DEVICE_NAME,O_RDWR);
printf("fd == %d\n",fd);

if(fd == -1)
{
printf("open failed!\n");
}
else
{
while(1)
{
i = read(fd,buf,1);

printf("i == %d\n",i);

printf("keyvalue == %d\n",buf);
}
}
return 0;
}

这是我的read函数读的时候总是返回-1
static int keypad_read(struct file *filp ,int *buf,size_t count,loff_t *f_pos)
{
intdate;

memset(date,0,5);
   date = keyvalue;
__copy_to_user(buf, date, count);


return 0;

}

EZWORD 发表于 2011-01-21 16:37

return 0;
?

lilysulia 发表于 2011-01-21 16:42

就是回复一个返回值，函数是INT 型的，这个地方有错了？

0vk0 发表于 2011-01-21 18:04

请把你的代码贴全一点，我说的是驱动代码

amarant 发表于 2011-01-22 08:30

不能返回0，否则会一直读

amarant 发表于 2011-01-22 08:31

你试试改成return 1; 看看~

lilysulia 发表于 2011-01-24 08:56

本帖最后由 lilysulia 于 2011-01-24 08:57 编辑

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/kthread.h>
#include <linux/init.h>
#include <linux/sched.h>
#include <mach/board.h>
#include <mach/gpio.h>
#include <linux/err.h>
#include <linux/delay.h>
#include <linux/poll.h>
#include "gpio.h"

static struct task_struct *test_task;
extern void msleep(unsigned int msecs);
int keyvalue;

int get_key7_stat(void)
{
at91_set_gpio_input(AT91_PIN_PB7,1);
return at91_get_gpio_value(AT91_PIN_PB7);
}
int get_key6_stat(void)
{
   at91_set_gpio_input(AT91_PIN_PB6,1);
   return at91_get_gpio_value(AT91_PIN_PB6);
}

void led_init(void)
{
at91_set_GPIO_periph(AT91_PIN_PB7,1);
at91_set_GPIO_periph(AT91_PIN_PB6,1);

at91_set_A_periph(AT91_PIN_PB7,1);
at91_set_A_periph(AT91_PIN_PB6,1);

}

static int example_kernel_thread(void *k)
{
unsigned int i = 0;
unsigned int j = 0;

set_current_state(TASK_UNINTERRUPTIBLE);
   while(1){
      if(kthread_should_stop()) break;
      //printk(KERN_WARNING "sss\n");


if(get_key7_stat() == 0)
{
                           msleep(10);
i++;
if(i == 4)
{
                              keyvalue = 1;
      printk("kernel1111 keyvalue == %d\n",keyvalue);

}
if(i == 12)
{
i = 0;
keyvalue = 0;
}
//msleep(100);

}
else if(get_key6_stat() == 0)
{


msleep(10);
                           j++;
                           if(j == 4)
                           {
keyvalue = 2;
printk("kernel2222 keyvalue == %d\n",keyvalue);
                           }
                           if(j == 12)
                              {
                                    j = 0;
keyvalue = 0;
                              }

      }
}
   return 0;
}

ssize_t keypad_open(struct inode *inode ,struct file *file)
{
return 0;
}

ssize_t keypad_read(struct file *filp ,char *buf,size_t count,loff_t *f_pos)
{
chardate;

printk("kernel keyvalue == %d\n",keyvalue);
if(keyvalue)
{
memset(date,0,5);
memset(buf,0,5);
      date = keyvalue;
__copy_to_user(buf, date, count);
   }
   return 1;

}

static void hello_exit(void)
{
      if(test_task){
            kthread_stop(test_task);
            test_task = NULL;
      }
      printk(KERN_WARNING "exit gpio\n");
}

static struct file_operations keypad_fops =
{
         open: keypad_open,
         read: keypad_read,
};

static int hello_init(void)
{

   int ret;
   int err;
   err = register_chrdev(0, "key_test_by_zkw", &keypad_fops);
   printk(" register device NO. is: %x\n",err);

   if (err < 0)
            {
            printk("%s (%s,%d) : Error registering s3c2410-keypad.\n",
                     __FUNCTION__, __FILE__, __LINE__);
               return err;
            }
   else
         {
            printk("%s (%s,%d) : s3c2410telekeypad registered.\n",
                     __FUNCTION__, __FILE__, __LINE__);
            }

      test_task = kthread_create(example_kernel_thread, NULL, "gpio");

if(IS_ERR(test_task)){
      printk(KERN_ALERT "kernel_thread gpio create failed \n");
      ret = PTR_ERR(test_task);
      test_task = NULL;
      return ret;
}else{
printk(KERN_WARNING "kernel_thread gpio create success \n");
wake_up_process(test_task);
led_init();
}

return 0;
}

module_init(hello_init);
module_exit(hello_exit);

MODULE_DESCRIPTION("gpio test");
MODULE_LICENSE("GPL");

lilysulia 发表于 2011-01-24 08:59

我发现现在的问题是Main函数根本调不到驱动中的read函数，打印语句根本出不来，请各位看看什么原因谢谢！

EZWORD 发表于 2011-01-24 09:40

能再把步骤详细的写出来看看吗？所有打印信息也贴出来

lilysulia 发表于 2011-01-24 09:58

# insmod gpio.ko
register device NO. is: fb
hello_init (/home/sulia/qudong/keyctl/gpio.c,180) : s3c2410telekeypad registere.
kernel_thread gpio create success
证明驱动注册成功

# ./main
fd == 3
文件读取成功，

下面按键

kernel2222 keyvalue == 2
kernel2222 keyvalue == 2
kernel2222 keyvalue == 2
kernel2222 keyvalue == 2
kernel1111 keyvalue == 1
kernel1111 keyvalue == 1
kernel2222 keyvalue == 2
kernel2222 keyvalue == 2
kernel1111 keyvalue == 1

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读不到内核数据，请各位看看啥原因