1.引入驅動的分離分層
input系統把驅動分成input_handler和input_device。讓內核專注於純軟件,驅動工程師專注於硬件。
我們引入驅動的分離分層
還是參考gpio_keys.c
它的入口函數是諸如一個平臺driver結構體
裏面有一個.probe函數,我們只關心probe函數
2.引入bus_drv_dev模型
bus虛擬總線類型,裏面有.match。用於device和driver建立聯繫
match裏使用到了strnmp函數,說明drv->name和pdev->name的有相同的名字,如platform_driver 變量gpio_keys_device_driver裏的.driver的name是"gpio-keys"。那麼必定,模型左邊的device必定有一個和它同名的設備,可惜gpio_keys.c只是一個例子。下面我們自己寫一個bus_drv_dev模型的驅動
分析:
0.bus是總線
1.driver和device向上註冊到bus的鏈表。device和driver建立聯繫是通過.match函數(在 platform_driver_register的platform_bus_type結構體中)
2.內核會從bus的drv鏈表取出每一個drv,用bus的match函數,判斷drv能否支持dev
3.若能夠支持(有同名的設備),就調用drv的probe函數。
4.這個模式只是一種機制,device和driver只不過是結構體,硬件相關,以及穩定的純軟件代碼
5.當我們修改代碼時,只需要修改左邊的硬件相關部分代碼
3. bus_drv_dev模型的驅動——新的點亮led
寫出兩個文件,myled_bus_driver.c和myled_bus_device.c
myled_bus_driver.c幫我們做好了一切:probe函數,映射地址,註冊,創建設備節點,讀寫函數等
myled_bus_device.c只需要設置改引腳的物理參數就行。
下面先寫兩個文件的框架,只打印,驗證同名設備driver和device的連接
myled_bus_driver.c:
/* 分配/設置/註冊一個platform_driver */
#include <linux/module.h>
#include <linux/version.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/sched.h>
#include <linux/pm.h>
#include <linux/sysctl.h>
#include <linux/proc_fs.h>
#include <linux/delay.h>
#include <linux/platform_device.h>
#include <linux/input.h>
#include <linux/irq.h>
#include <asm/uaccess.h>
#include <asm/io.h>
static int led_probe(struct platform_device *pdev)
{
printk("led_probe, insmod led\n");
return 0;
}
static int led_remove(struct platform_device *pdev)
{
/* 卸載字符設備驅動程序 */
/* iounmap */
printk("led_remove, remove led\n");
return 0;
}
struct platform_driver led_drv = {
.probe = led_probe,
.remove = led_remove,
.driver = {
.name = "myled", //設備名
}
};
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");
myled_bus_device.c:
#include <linux/module.h>
#include <linux/version.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/interrupt.h>
#include <linux/list.h>
#include <linux/timer.h>
#include <linux/init.h>
#include <linux/serial_core.h>
#include <linux/platform_device.h>
/* 分配/設置/註冊一個platform_device */
static struct resource led_resource[] = {
[0] = {
.start = 0x56000050,
.end = 0x56000050 + 8 - 1,
.flags = IORESOURCE_MEM,
},
[1] = {
.start = 4,
.end = 4,
.flags = IORESOURCE_IRQ,
}
};
static void led_release(struct device * dev) // release不做任何事情,自動會去調用bus的release
{
}
static struct platform_device led_dev = {
.name = "myled",
.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");
Makefile:
KERN_DIR = /work/system/linux-2.6.22.6
all:
make -C $(KERN_DIR) M=`pwd` modules
clean:
make -C $(KERN_DIR) M=`pwd` modules clean
rm -rf modules.order
obj-m += myled_bus_device.o
obj-m += myled_bus_driver.o
測試:
先裝載driver,再裝載device時,同名匹配成功,自動調用probe函數,卸載自動調用remove函數。
4.完善代碼
框架弄好後,就又回到以前的註冊,創建類設備,.....
只改 driver文件,只測試按鍵2
/* 分配/設置/註冊一個platform_driver */
#include <linux/module.h>
#include <linux/version.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/sched.h>
#include <linux/pm.h>
#include <linux/sysctl.h>
#include <linux/proc_fs.h>
#include <linux/delay.h>
#include <linux/platform_device.h>
#include <linux/input.h>
#include <linux/irq.h>
#include <asm/uaccess.h>
#include <asm/io.h>
static int major;
static struct class *cls;
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)
{
//printk("first_drv_open\n");
/* 配置爲輸出 */
*gpio_con &= ~(0x3<<(pin*2));
*gpio_con |= (0x1<<(pin*2));
return 0;
}
static ssize_t led_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); // copy_to_user();
if (val == 1)
{
// 點燈
*gpio_dat &= ~(1<<pin);
}
else
{
// 滅燈
*gpio_dat |= (1<<pin);
}
return 0;
}
static struct file_operations led_fops = {
.owner = THIS_MODULE, /* 這是一個宏,推向編譯模塊時自動創建的__this_module變量 */
.open = led_open,
.write = led_write,
};
static int led_probe(struct platform_device *pdev)
{
struct resource *res;
/* 根據platform_device的資源進行ioremap */
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;
/* 註冊字符設備驅動程序 */
printk("led_probe, found led\n");
major = register_chrdev(0, "myled", &led_fops);
cls = class_create(THIS_MODULE, "myled");
class_device_create(cls, NULL, MKDEV(major, 0), NULL, "myled"); /* /dev/led */
return 0;
}
static int led_remove(struct platform_device *pdev)
{
/* 卸載字符設備驅動程序 */
/* iounmap */
printk("led_remove, remove led\n");
class_device_destroy(cls, MKDEV(major, 0));
class_destroy(cls);
unregister_chrdev(major, "myled");
iounmap(gpio_con);
return 0;
}
struct platform_driver led_drv = {
.probe = led_probe,
.remove = led_remove,
.driver = {
.name = "myled",
}
};
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");
測試代碼:
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
/* led_test on
* led_test off
*/
int main(int argc, char **argv)
{
int fd;
int val = 1;
fd = open("/dev/myled", O_RDWR);
if (fd < 0)
{
printf("can't open!\n");
}
if (argc != 2)
{
printf("Usage :\n");
printf("%s <on|off>\n", argv[0]);
return 0;
}
if (strcmp(argv[1], "on") == 0)
{
val = 1;
}
else
{
val = 0;
}
write(fd, &val, 4);
return 0;
}