2025-03-25
struct work_struct是Linux内核中用于实现延迟工作（deferred work）机制的重要数据结构，属于工作队列（workqueue）子系统的一部分。
延迟执行：允许将任务推迟到内核线程上下文中执行
进程上下文：工作在进程上下文中运行，可以睡眠
异步处理：常用于中断下半部（bottom half）处理
// test.dst
/dts-v1/;
/ {
#address-cells = <1>;
#size-cells = <1>;
// 模拟数据
gpioe:gpio@50006000 {
#gpio-cells = <0x2>;
reg = <0x50006000 0x4 0x50006014 0x4 0x50000a28 0x4>;
};
// 模拟数据
gpiof:gpio@50008000 {
gpio-controller;
#gpio-cells = <0x2>;
interrupt-controller;
#interrupt-cells = <0x2>;
reg = <0x50008000 0x4 0x50008014 0x4 0x50008a28 0x4>;
gpio-ranges = <0x55 0x0 0x50 0x10>;
status = "okay";
};
// 该节点会被转换为`struct platform_device`设备对象
led {
model = "This is LED";
dev-type = "LED";
// 参数：gpio对象引用，第几个引脚，是否使能
led-gpios = <&gpioe 10 0>,<&gpiof 10 0>,<&gpioe 8 0>;
// 与驱动匹配的关键设置
compatible = "my_device_001";
// 表示启用设备节点
status = "okay";
};
key {
model = "This is key";
dev-type = "KEY";
interrupt-parent = <&gpiof>;
interrupts = <9 0>,<7 0>,<8 0>;
key-gpios = <&gpiof 9 0>,<&gpiof 7 0>,<&gpiof 8 0>;
// 与驱动匹配的关键设置
compatible = "my_device_002";
// 表示启用设备节点
status = "okay";
};
};
// simple.c
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/of_gpio.h>
#include <linux/of_irq.h>
#include <linux/platform_device.h>
#include <linux/workqueue.h>
#define PLATFORM_DEVICE_BASENAME "my_device"
#define PLATFORM_DEVICE_NAME_1 "my_device_001"
#define PLATFORM_DEVICE_NAME_2 "my_device_002"
static u32 led1_gpios;
static u32 key1_gpios;
static u32 key1_interrupts;
static int current_irq;
static struct work_struct work;
static irqreturn_t _key_ISR(int irq, void *dev) {
pr_info("call key_ISR irq = %d\n", irq);
current_irq = irq;
// 中断上文执行完后，会执行中断下文，即`_work`函数
schedule_work(&work);
return IRQ_HANDLED;
}
static void _work(struct work_struct *work) {
pr_info("call timeout\n");
msleep(100); // 阻塞延时100毫秒, 会放弃cpu的使用权
int irq = current_irq;
if (irq == key1_interrupts) {
if (gpio_get_value(key1_gpios) == 0) {
pr_info("key1 pressed\n");
} else {
pr_info("key1 released\n");
}
}
}
static int _probe(struct platform_device *device) {
pr_info("key_driver_probe\n");
// 初始化gpio资源, 第二个参数要与test.dts中的资源名称要一致
led1_gpios = of_get_named_gpio(device->dev.of_node, "led-gpios", 0);
gpio_request(led1_gpios, "led1-gpios");
gpio_direction_output(led1_gpios, 0);
struct device_node *key_node = of_find_node_by_path("/key");
if (!key_node) {
pr_err("simple of_find_node_by_path('\\key') failed\n");
return -1;
}
// 初始化gpio资源, 第二个参数要与test.dts中的资源名称要一致
key1_gpios = of_get_named_gpio(key_node, "key-gpios", 0);
gpio_request(key1_gpios, "key1-gpios");
gpio_direction_input(key1_gpios);
key1_interrupts = of_irq_get(key_node, 0);
// 会创建`/proc/irq/key1-interrupts`目录
int ret = request_irq(key1_interrupts, _key_ISR,
IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
"key1-interrupts", NULL);
if (ret) {
pr_err("request_irq for key1 failed\n");
return -1;
}
INIT_WORK(&work, _work);
return 0;
}
// 当平台设备驱动卸载时，会自动调用该函数
static int _remove(struct platform_device *device) {
pr_info("key_driver_remove\n");
free_irq(key1_interrupts, NULL);
gpio_free(key1_gpios);
gpio_free(led1_gpios);
cancel_work_sync(&work);
return 0;
}
// 会与insmod安装的platform_device进行匹配
struct platform_device_id id_table_match[] = {
// 名称要在20个字节以内
[0] = {PLATFORM_DEVICE_NAME_1, 1},
[1] = {PLATFORM_DEVICE_NAME_2, 2},
[2] = {}, // 空元素代表结束
};
// 会与设备树安装的platform_device进行匹配
struct of_device_id of_node_match_table[] = {
[0] = {.compatible = PLATFORM_DEVICE_NAME_1},
[1] = {.compatible = PLATFORM_DEVICE_NAME_2},
[2] = {}, // 空元素代表结束
};
struct platform_driver key_driver = {
.probe = _probe,
.remove = _remove,
// 通过id_table匹配, 实现一个驱动对多个设备
.driver =
{
.name = PLATFORM_DEVICE_BASENAME,
// 设备树的匹配方式
.of_match_table = of_node_match_table,
},
.id_table = id_table_match,
};
static int __init key_driver_init(void) {
pr_info("key_driver_init\n");
int ret = platform_driver_register(&key_driver);
if (ret < 0) {
pr_err("key_driver_register failed\n");
return -1;
}
return 0;
}
static void __exit key_driver_exit(void) {
pr_info("key_driver_exit\n");
platform_driver_unregister(&key_driver);
}
module_init(key_driver_init);
module_exit(key_driver_exit);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("heng30");
MODULE_VERSION("v0.0.1");
MODULE_DESCRIPTION("A simple key_driver kernel module");
#!/bin/sh
top-dir = $(shell pwd)
kernel-version = $(shell uname -r)
kernel-dir ?= /lib/modules/$(kernel-version)/build
obj-m += simple.o
all: dt driver
driver:
make -C $(kernel-dir) modules M=$(top-dir)
dt:
dtc -@ -I dts -O dtb -o test.dtbo test.dts
clean:
rm -f *.o *.ko *.mod *.mod.c *.order *.symvers *.dtbo
make -C $(kernel-dir) clean m=$(top-dir)