Linux 驱动开发基础知识——编写LED驱动程序（三）

 
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/delay.h>
#include <linux/poll.h>
#include <linux/mutex.h>
#include <linux/wait.h>
#include <linux/uaccess.h>
#include <linux/device.h>
#include <asm/io.h>
 
static int major;
static struct class *led_class;
 
/* registers */
// IOMUXC_SNVS_SW_MUX_CTL_PAD_SNVS_TAMPER3 地址：0x02290000 + 0x14
static volatile unsigned int *IOMUXC_SNVS_SW_MUX_CTL_PAD_SNVS_TAMPER3;
 
// GPIO5_GDIR 地址：0x020AC004
static volatile unsigned int *GPIO5_GDIR;
 
//GPIO5_DR 地址：0x020AC000
static volatile unsigned int *GPIO5_DR;
 
static ssize_t led_write(struct file *filp, const char __user *buf,
       size_t count, loff_t *ppos)
{
  char val;
  int ret;
  
  /* copy_from_user : get data from app */
  ret = copy_from_user(&val, buf, 1);
 
  /* to set gpio register: out 1/0 */
  if (val)
  {
    /* set gpio to let led on */
    *GPIO5_DR &= ~(1<<3);
  }
  else
  {
 
    /* set gpio to let led off */
    *GPIO5_DR |= (1<<3);
  }
  return 1;
}
 
static int led_open(struct inode *inode, struct file *filp)
{
  /* enable gpio5
   * configure gpio5_io3 as gpio
   * configure gpio5_io3 as output 
   */
  *IOMUXC_SNVS_SW_MUX_CTL_PAD_SNVS_TAMPER3 &= ~0xf;
  *IOMUXC_SNVS_SW_MUX_CTL_PAD_SNVS_TAMPER3 |= 0x5;
 
  *GPIO5_GDIR |= (1<<3);
  
  return 0;
}
 
static struct file_operations led_fops = {
  .owner    = THIS_MODULE,
  .write    = led_write,
  .open   = led_open,
};
 
/* 入口函数 */
static int __init led_init(void)
{
  printk("%s %s %d\n", __FILE__, __FUNCTION__, __LINE__);
  
  major = register_chrdev(0, "100ask_led", &led_fops);
 
  /* ioremap */
  // IOMUXC_SNVS_SW_MUX_CTL_PAD_SNVS_TAMPER3 地址：0x02290000 + 0x14
  IOMUXC_SNVS_SW_MUX_CTL_PAD_SNVS_TAMPER3 = ioremap(0x02290000 + 0x14, 4);
  
  // GPIO5_GDIR 地址：0x020AC004
  GPIO5_GDIR = ioremap(0x020AC004, 4);
  
  //GPIO5_DR 地址：0x020AC000
  GPIO5_DR  = ioremap(0x020AC000, 4);
 
  led_class = class_create(THIS_MODULE, "myled");
  device_create(led_class, NULL, MKDEV(major, 0), NULL, "myled"); /* /dev/myled */
  
  return 0;
}
 
static void __exit led_exit(void)
{
  iounmap(IOMUXC_SNVS_SW_MUX_CTL_PAD_SNVS_TAMPER3);
  iounmap(GPIO5_GDIR);
  iounmap(GPIO5_DR);
  
  device_destroy(led_class, MKDEV(major, 0));
  class_destroy(led_class);
  
  unregister_chrdev(major, "100ask_led");
}
 
module_init(led_init);
module_exit(led_exit);
MODULE_LICENSE("GPL");
 
 

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>
#include <stdio.h>
 
 
// ledtest /dev/myled on
// ledtest /dev/myled off
 
int main(int argc, char **argv)
{
  int fd;
  char status = 0;
  
  if (argc != 3)
  {
    printf("Usage: %s <dev> <on|off>\n", argv[0]);
    printf("  eg: %s /dev/myled on\n", argv[0]);
    printf("  eg: %s /dev/myled off\n", argv[0]);
    return -1;
  }
  // open
  fd = open(argv[1], O_RDWR);
  if (fd < 0)
  {
    printf("can not open %s\n", argv[0]);
    return -1;
  }
 
  // write
  if (strcmp(argv[2], "on") == 0)
  {
    status = 1;
  }
 
  write(fd, &status, 1);
  return 0; 
}
 

 
# 1. 使用不同的开发板内核时, 一定要修改KERN_DIR
# 2. KERN_DIR中的内核要事先配置、编译, 为了能编译内核, 要先设置下列环境变量:
# 2.1 ARCH,          比如: export ARCH=arm64
# 2.2 CROSS_COMPILE, 比如: export CROSS_COMPILE=aarch64-linux-gnu-
# 2.3 PATH,          比如: export PATH=$PATH:/home/book/100ask_roc-rk3399-pc/ToolChain-6.3.1/gcc-linaro-6.3.1-2017.05-x86_64_aarch64-linux-gnu/bin 
# 注意: 不同的开发板不同的编译器上述3个环境变量不一定相同,
#       请参考各开发板的高级用户使用手册
 
KERN_DIR = /home/book/100ask_imx6ull-sdk/Linux-4.9.88
 
all:
  make -C $(KERN_DIR) M=`pwd` modules 
  $(CROSS_COMPILE)gcc -o ledtest ledtest.c 
 
clean:
  make -C $(KERN_DIR) M=`pwd` modules clean
  rm -rf modules.order
  rm -f ledtest
 
obj-m += led_drv.o
 

[root@100ask:~]# echo "7 4 1 7" > /proc/sys/kernel/printk // 打开内核的打印信息，有些
板子默认打开了
[ 1426.505931] /home/book/05_嵌入式Linux驱动开发基础知识/source/02_led_drv/00_led_drv_simple/imx6ull/led_drv.c led_init 75    //安装后打印的信息
[root@100ask:~]# insmod /mnt/led_drv.ko    //安装驱动
[root@100ask:~]# lsmod                     //查询驱动
[root@100ask:~]# rmmod /mnt/led_drv.ko     //卸载驱动
/mnt/ledtest /dev/myled on                 // 点灯
/mnt/ledtest /dev/myled off                // 关灯