驱动调试(五)寄存器读写

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title: 驱动调试(五)寄存器读写
date: 2019/1/14 22:30:32
toc: true

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:
");
	printf("%s <r8 | r16 | r32> <phy addr> [num]
", file);
	printf("%s <w8 | w16 | w32> <phy addr> <val>
", 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
");
		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
", 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
", 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
", 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;
	
}