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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
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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[] = {
[] = {
.start= 0x56000050,
.end= 0x56000050 + - ,
.flags= IORESOURCE_MEM,
},
[] = {
.start= , //第4个引脚
.end= ,
.flags= IORESOURCE_IRQ,
},
}; void led_release(struct device * dev)
{ } static struct platform_device led_dev = {
.name= "myled",
.id= -,
.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 ;
} 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*));
*gpio_con |= 0x1<<(pin*);
return ;
} ssize_t led_write(struct file *file, const char *buff, size_t len, loff_t *pos )
{
int val;
copy_from_user(&val, buff, );
val &= 0x1;
*gpio_dat &= ~(<<pin);
*gpio_dat |= (val<<pin); return ;
} 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\n"); res = platform_get_resource(pdev,IORESOURCE_MEM,);
gpio_con = ioremap(res->start,res->end-res->start + );
gpio_dat = gpio_con + ; res = platform_get_resource(pdev,IORESOURCE_IRQ,);
pin = res->start; major = register_chrdev(,"myled", &led_fops );
led_class = class_create(THIS_MODULE,"myled");
led_class_dev = class_device_create(led_class,NULL,MKDEV(major,),NULL,"led%d",pin); return ;
} 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\n");
return ;
} 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 ;
} 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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