驱动调试(五)寄存器读写
驱动调试(五)寄存器读写
这个章节没什么新知识,就是先写一个能够读写寄存器的驱动,再写一个app调用提供的读写接口
bug
这里应该有个问题,就是当传入的地址不是4字节对齐的时候,读取u32的时候,指针转换是有问题的,但实际上这也属于app传输进来的错误
驱动程序
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/irq.h>
#include <asm/uaccess.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <asm/arch/regs-gpio.h>
#include <asm/hardware.h>
#include <linux/poll.h>
#include <linux/device.h>
#define KER_RW_R8 0
#define KER_RW_R16 1
#define KER_RW_R32 2
#define KER_RW_W8 3
#define KER_RW_W16 4
#define KER_RW_W32 5
static int major;
static struct class *class;
static struct class_device *ker_dev;
static int ker_rw_ioctl(struct inode *inode, struct file *file, unsigned int cmd, unsigned long arg)
{
volatile unsigned char *p8;
volatile unsigned short *p16;
volatile unsigned int *p32;
unsigned int val;
unsigned int addr;
unsigned int buf[2];
copy_from_user(buf, (const void __user *)arg, 8);
addr = buf[0];
val = buf[1];
p8 = (volatile unsigned char *)ioremap(addr, 4);
p16 = p8;
p32 = p8;
switch (cmd)
{
case KER_RW_R8:
{
val = *p8;
copy_to_user((void __user *)(arg+4), &val, 4);
break;
}
case KER_RW_R16:
{
val = *p16;
copy_to_user((void __user *)(arg+4), &val, 4);
break;
}
case KER_RW_R32:
{
val = *p32;
copy_to_user((void __user *)(arg+4), &val, 4);
break;
}
case KER_RW_W8:
{
*p8 = val;
break;
}
case KER_RW_W16:
{
*p16 = val;
break;
}
case KER_RW_W32:
{
*p32 = val;
break;
}
}
iounmap(p8);
return 0;
}
static struct file_operations ker_rw_ops = {
.owner = THIS_MODULE,
.ioctl = ker_rw_ioctl,
};
static int ker_rw_init(void)
{
major = register_chrdev(0, "ker_rw", &ker_rw_ops);
class = class_create(THIS_MODULE, "ker_rw");
/* 为了让mdev根据这些信息来创建设备节点 */
ker_dev = class_device_create(class, NULL, MKDEV(major, 0), NULL, "ker_rw"); /* /dev/ker_rw */
return 0;
}
static void ker_rw_exit(void)
{
class_device_unregister(ker_dev);
class_destroy(class);
unregister_chrdev(major, "ker_rw");
}
module_init(ker_rw_init);
module_exit(ker_rw_exit);
MODULE_LICENSE("GPL");
APP程序
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <poll.h>
#include <signal.h>
#include <sys/types.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#define KER_RW_R8 0
#define KER_RW_R16 1
#define KER_RW_R32 2
#define KER_RW_W8 3
#define KER_RW_W16 4
#define KER_RW_W32 5
/* Usage:
* ./regeditor r8 addr [num]
* ./regeditor r16 addr [num]
* ./regeditor r32 addr [num]
*
* ./regeditor w8 addr val
* ./regeditor w16 addr val
* ./regeditor w32 addr val
*/
void print_usage(char *file)
{
printf("Usage:\n");
printf("%s <r8 | r16 | r32> <phy addr> [num]\n", file);
printf("%s <w8 | w16 | w32> <phy addr> <val>\n", file);
}
int main(int argc, char **argv)
{
int fd;
unsigned int buf[2];
unsigned int i;
unsigned int num;
if ((argc != 3) && (argc != 4))
{
print_usage(argv[0]);
return -1;
}
fd = open("/dev/ker_rw", O_RDWR);
if (fd < 0)
{
printf("can't open /dev/ker_rw\n");
return -2;
}
/* addr */
buf[0] = strtoul(argv[2], NULL, 0);
if (argc == 4)
{
buf[1] = strtoul(argv[3], NULL, 0);
num = buf[1];
}
else
{
num = 1;
}
if (strcmp(argv[1], "r8") == 0)
{
for ( i = 0; i < num; i++)
{
ioctl(fd, KER_RW_R8, buf); /* val = buf[1] */
printf("%02d. [%08x] = %02x\n", i, buf[0], (unsigned char)buf[1]);
buf[0] += 1;
}
}
else if (strcmp(argv[1], "r16") == 0)
{
for ( i = 0; i < num; i++)
{
ioctl(fd, KER_RW_R16, buf); /* val = buf[1] */
printf("%02d. [%08x] = %02x\n", i, buf[0], (unsigned short)buf[1]);
buf[0] += 2;
}
}
else if (strcmp(argv[1], "r32") == 0)
{
for ( i = 0; i < num; i++)
{
ioctl(fd, KER_RW_R32, buf); /* val = buf[1] */
printf("%02d. [%08x] = %02x\n", i, buf[0], (unsigned int)buf[1]);
buf[0] += 4;
}
}
else if (strcmp(argv[1], "w8") == 0)
{
ioctl(fd, KER_RW_W8, buf); /* val = buf[1] */
}
else if (strcmp(argv[1], "w16") == 0)
{
ioctl(fd, KER_RW_W16, buf); /* val = buf[1] */
}
else if (strcmp(argv[1], "w32") == 0)
{
ioctl(fd, KER_RW_W32, buf); /* val = buf[1] */
}
else
{
printf(argv[0]);
return -1;
}
return 0;
}