am335x led驱动。

来源：互联网发布：淘宝排名收费编辑：程序博客网时间：2024/06/18 13:45

今天尝试用两种方式实现AM335X的点灯驱动。

第一种使用ioremap实现操作相关寄存器去控制点灯，灭灯

#include <linux/init.h>
#include <linux/export.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/errno.h>
#include <linux/miscdevice.h>
#include <linux/types.h>
#include <linux/io.h>
#include <linux/fs.h>
#include <linux/gpio.h>
#include <asm/gpio.h>
#include <asm/uaccess.h>
#include <mach/hardware.h>
#include <mach/board-am335xevm.h>
#include <asm-generic/gpio.h>

static struct class *firstdrv_class;
volatile unsigned long *GPIO_OE = NULL;
volatile unsigned long *GPIO_DATAOUT = NULL;

static int first_drv_open(struct inode *inode, struct file *file)
{
printk("first_drv_open\n");
*GPIO_OE &= ~((1<<21)|(1<<22));
return 0;
}

static ssize_t first_drv_write(struct file *file, const char __user *buf, size_t count, loff_t * ppos)
{
int val;
//printk("first_drv_write\n");
copy_from_user(&val, buf, count);
if (val == 1)
{
// 点灯
*GPIO_DATAOUT &= ~((1<<21)|(1<<22));
}
else
{
// 灭灯
*GPIO_DATAOUT |= (1<<21)|(1<<22);
}
return 0;
}

static struct file_operations first_drv_fops = {
.owner = THIS_MODULE,
.open = first_drv_open,
.write = first_drv_write,
};

int major;
static int first_drv_init(void)
{
major = register_chrdev(0, "first_drv", &first_drv_fops);

firstdrv_class = class_create(THIS_MODULE, "firstdrv");
device_create(firstdrv_class, NULL, MKDEV(major, 0), NULL, "xyz"); /* /dev/xyz */

GPIO_OE = (volatile unsigned long *)ioremap(0x4804c134, sizeof(GPIO_OE));
//GPIO_DATAOUT = (volatile unsigned long *)ioremap(0x4804c13c, 16);
GPIO_DATAOUT = GPIO_OE+2;
return 0;
}

static void first_drv_exit(void)
{
unregister_chrdev(major, "first_drv");
device_destroy(firstdrv_class,MKDEV(major, 0));
class_destroy(firstdrv_class);
iounmap(GPIO_OE);
//iounmap(GPIO_DATAOUT);
}
module_init(first_drv_init);
module_exit(first_drv_exit);
MODULE_LICENSE("GPL");

第二种使用内核提供的操作GPIO函数

static int first_drv_open(struct inode *inode, struct file *file)
{
printk("first_drv_open\n");
gpio_direction_output(53, 1);
gpio_direction_output(54, 1);
return 0;
}

static ssize_t first_drv_write(struct file *file, const char __user *buf, size_t count, loff_t * ppos)
{
int val;
//printk("first_drv_write\n");
copy_from_user(&val, buf, count);
if (val == 1)
{
// 点灯
gpio_set_value(GPIO_TO_PIN(1, 21), 0);
gpio_set_value(GPIO_TO_PIN(1, 22), 0);
printk("open led\n");
}
else
{
// 灭灯
gpio_set_value(GPIO_TO_PIN(1, 21), 1);
gpio_set_value(GPIO_TO_PIN(1, 22), 1);
printk("close led\n");
}
return 0;
}

static struct file_operations first_drv_fops = {
.owner = THIS_MODULE,
.open = first_drv_open,
.write = first_drv_write,
};

int major;
static int first_drv_init(void)
{
major = register_chrdev(0, "first_drv", &first_drv_fops);

firstdrv_class = class_create(THIS_MODULE, "firstdrv");
device_create(firstdrv_class, NULL, MKDEV(major, 0), NULL, "xyz"); /* /dev/xyz */
return 0;
}

static void first_drv_exit(void)
{
unregister_chrdev(major, "first_drv");
device_destroy(firstdrv_class,MKDEV(major, 0));
class_destroy(firstdrv_class);
}

module_init(first_drv_init);

module_exit(first_drv_exit);

MODULE_LICENSE("GPL");

----------------------------------------------------------------------------------------------------

am335x -- led 控制

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
int main(void)
{

FILE *p=NULL;
int i=0;
p = fopen("/sys/class/gpio/export","w");
fprintf(p,"%d",38);
fclose(p);
p = fopen("/sys/class/gpio/gpio38/direction","w");
fprintf(p,"out");
fclose(p);
for(i=0;i<100;i++)
{
  p = fopen("/sys/class/gpio/gpio38/value","w");
  fprintf(p,"%d",1);
  sleep(1);
  fclose(p);
  p = fopen("/sys/class/gpio/gpio38/value","w");
  fprintf(p,"%d",0);
  sleep(1);
  fclose(p);
}
p = fopen("/sys/class/gpio/unexport","w");
fprintf(p,"%d",38);
fclose(p);
return 0;
}

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