嵌入式Linux驱动学习之路(十七)驱动程序分层分离概念-平台设备驱动

 平台设备驱动：

　　包含BUS（总线)、DEVICE、DRIVER。

　　DEVICE：硬件相关的代码

　　DRIVER：比较稳定的代码　　

　　BUS有一个driver链表和device链表。

　　　　①把device放入bus的device链表中

　　　　②从bus的drv链表中取出每一个drv，用bus的match函数判断drv能否支持dev。

　　　　③如果可以执行，则调用probe函数。

　　driver和device类似。

device驱动程序代码：

/**
  * file name： led_dev.c
  */
#include <linux/platform_device.h>
#include <asm/mach/arch.h>
#include <asm/mach/map.h>


/* 分配注册一个平台device结构体 */
static struct resource led_resources[] = {
    [0] = {
        .start= 0x56000050,
        .end= 0x56000050 + 8 - 1,
        .flags= IORESOURCE_MEM,
    },
    [1] = {
        .start= 5,  //第4个引脚
        .end= 5,
        .flags= IORESOURCE_IRQ,      
    },
};

void led_release(struct device * dev)
{ }

static struct platform_device led_dev = {
    .name= "myled",
    .id= -1,
    .resource= led_resources,
    .num_resources= ARRAY_SIZE(led_resources),
    .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);
    return ;
}

module_init(led_dev_init);
module_exit(led_dev_exit);
MODULE_LICENSE("GPL");

driver驱动程序代码：

/**
   * file name:led_driver.c
   */
#include <linux/platform_device.h>
#include <asm/mach/arch.h>
#include <asm/mach/map.h>
#include <linux/sched.h>
#include <linux/signal.h>
#include <linux/spinlock.h>
#include <linux/errno.h>
#include <linux/random.h>
#include <linux/poll.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/wait.h>
#include <linux/mutex.h>
#include <linux/io.h>
#include <linux/fs.h>

static int major;

struct class *led_class;
struct class_device *led_class_dev;
static volatile unsigned long *gpio_con;
static volatile unsigned long *gpio_dat;
static int pin;

static int led_open(struct inode *inode, struct file *file)
{
    *gpio_con &= ~(0x3<<(pin*2));
    *gpio_con |= 0x1<<(pin*2);
    return 0;
}

ssize_t led_write(struct file *file, const char  *buff, size_t len, loff_t *pos )
{
    int val;
    copy_from_user(&val, buff, 1);
    val &= 0x1;
    *gpio_dat &= ~(1<<pin);
    *gpio_dat |= (val<<pin);

    return 0; 
}

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


static int led_probe(struct platform_device *pdev)
{
    struct resource *res;

    printk("led drv probe
");
    
    res = platform_get_resource(pdev,IORESOURCE_MEM,0);
    gpio_con = ioremap(res->start,res->end-res->start + 1);
    gpio_dat = gpio_con + 1;
    
    res = platform_get_resource(pdev,IORESOURCE_IRQ,0);
    pin = res->start;
    
    major = register_chrdev(0,"myled", &led_fops );
    led_class = class_create(THIS_MODULE,"myled");
    led_class_dev = class_device_create(led_class,NULL,MKDEV(major,0),NULL,"led%d",pin);
    
    return 0;
}


static int led_remove(struct platform_device *pdev)
{
    iounmap(gpio_con);
    class_device_unregister(led_class_dev);
    class_destroy(led_class);
    unregister_chrdev( major,"myled");
    printk("led remove
");
    return 0;
}

struct platform_driver led_drv = {
    .driver={
        .owner=THIS_MODULE,
        .name = "myled",
    },
    .probe = led_probe,
    .remove= led_remove,
};

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

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

module_init(led_drv_init);
module_exit(led_drv_exit);
MODULE_LICENSE("GPL");

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