Linux平台设备驱动模型之led例程（TQ210）

首先编写设备层：
led_device.c

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <asm/uaccess.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <linux/device.h>//classcreate的定义
#include <linux/gpio.h>//gpio结构体的定义
#include <mach/regs-gpio.h>
//linux 3.10内核的regs-gpio.h位置不再是<asm/arch/regs-gpio.h>
#include <mach/hardware.h>
#include <linux/platform_device.h>

static struct resource led_resource[] = {
};

static void led_release(struct device * dev)
{
}

static struct platform_device led_dev = {
    .name = "s5pv210_led",
    .id = -1,
    .num_resources = ARRAY_SIZE(led_resource),
    .resource = led_resource,
    .dev = {
        .release = led_release,
    },
};



static int led_dev_init(void)
{
    platform_device_register(&led_dev);
    return 0;
}

static void led_dev_exit(void)
{
    platform_device_unregister(&led_dev);
}

module_init(led_dev_init);
module_exit(led_dev_exit);

MODULE_LICENSE("GPL");

接下来写驱动层：
led_driver.c

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <asm/uaccess.h>
#include <asm/irq.h>
#include <asm/io.h>
#include <linux/device.h>//classcreate的定义
#include <linux/gpio.h>//gpio结构体的定义
#include <mach/regs-gpio.h>
//linux 3.10内核的regs-gpio.h位置不再是<asm/arch/regs-gpio.h>
#include <mach/hardware.h>
#include <linux/platform_device.h>

volatile unsigned long *gpc0con = NULL;
volatile unsigned long *gpc0pud = NULL;
volatile unsigned long *gpc0dat = NULL;

static struct class *led_drv_class;
static struct device *led_drv_class_dev;

///static volatile unsigned long *gpio_con;
//static volatile unsigned long *gpio_dat;

static int led_open(struct inode *inode, struct file *file)
{
    printk("led_drv_open\n");

    *gpc0con &= ~(0xf<<3*4);
    *gpc0con |= (0x1<<3*4);//1为输出模式
    *gpc0dat &= ~(0x1<<3);//gpc0_3
    *gpc0dat |= (0x0<<3);//高电平亮

    return 0;
}

static ssize_t led_write(struct file *file, const char __user *buf, size_t count, loff_t * ppos)
{

    int val;
    int ret;
    printk("led_drv_write\n");

    ret = copy_from_user(&val, buf, count); //    copy_to_user();
    if(ret)
    {
        printk("copy_from_user error\n");
        return -EFAULT;
    }
    if (val == 1)
    {
        *gpc0dat &= ~(0x1<<3);//高电平亮
        *gpc0dat |= (0x1<<3);
    }
    else
    {
        // gpc0dat = (*gpc0dat & ~(0x1<<3)) | (0x1<<3);
        *gpc0dat &= ~(0x1<<3);//
        *gpc0dat |= (0x0<<3);
    }

    return 0;
}

static struct file_operations led_fops = {
    .owner = THIS_MODULE,
    .open = led_open,
    .write    =    led_write,
};

int major;
static int led_probe(struct platform_device *pdev)
{
    struct resource        *res;
    /* 根据platform_device的资源进行ioremap */
    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    if(!res){
        printk("get resource error\n");
        return -1;
    }
    gpc0con = ioremap(res->start, res->end - res->start + 1);
    gpc0dat = gpc0con + 1;

    major = register_chrdev(0, "led_cdev", &led_fops);
    led_drv_class = class_create(THIS_MODULE,"class_led_cdev");
    led_drv_class_dev = device_create(led_drv_class, NULL,MKDEV(major, 0), NULL, "led");
    //MKDEV将主设备号和次设备号转为dev_t类型
    //device_create创建设备信息，udev会自动根据设备信息创建设备节点/dev/led，应用程序根据设备节点(路径)访问设备
    //linux 3.10中，class_device_create替换为device_create
    printk("led initialize\n");
    return 0;
}

static int led_remove(struct platform_device *pdev)
{
    printk("led_drv_exit\n");
    unregister_chrdev(major, "led_cdev");
    device_unregister(led_drv_class_dev);//linux 3.10中，class_device_unregister替换为device_unregister
    class_destroy(led_drv_class);
    return 0;
}

struct platform_driver led_drv = {
    .probe        = led_probe,
    .remove        = led_remove,
    .driver        = {
        .owner    = THIS_MODULE,    /* 一定要加上这句，否则运行测试程序会出现段错误 */
        .name    = "s5pv210_led",
    }
};

static int __init led_drv_init(void)
{
    platform_driver_register(&led_drv);
    return 0;
}

static void __exit led_drv_exit(void)
{
    platform_driver_unregister(&led_drv);
}

module_init(led_drv_init);
module_exit(led_drv_exit);

MODULE_LICENSE("GPL");

测试程序ledtest.c：

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>

/*    ledtest on
  * ledtest off
  */
int main(int argc, char **argv)
{
    int fd;
    int val = 1;
    fd = open("/dev/led", O_RDWR);
    if (fd < 0)
    {
        printf("can't open!\n");
    }
    if (argc != 2)
    {
        printf("Usage :\n");
        printf("%s \n", argv[0]);
        return 0;
    }

    if (strcmp(argv[1], "on") == 0)
    {
        val = 1;
    }
    else
    {
        val = 0;
    }

    write(fd, &val, 4);
    return 0;
}

Makefile:

KERN_DIR = /home/richard/work/kernel/linux-3.10.80
obj-m += led_device.o led_driver.o

all:
    make -C $(KERN_DIR) M=`pwd` modules
    arm-linux-gnueabi-gcc -o ledtest ledtest.c
clean:
    rm -rf *.ko *.mod.c *.mod.o *.o *.order *.symvers *.cmd .*.o.* .*.ko.*

cdev_add方式参考
http://blog.chinaunix.net/uid-30031530-id-5096590.html
https://blog.csdn.net/wangdapao12138/article/details/82193246