题目
使用驱动代码实现如下要求:文章来源:https://www.toymoban.com/news/detail-599427.html
- 使用驱动通过阻塞 io 模型读取 number 变量的值
- number 是内核驱动中的一个变量
- number 的值随着按键按下而改变(按键中断)
- 例如 number = 0 按下按键 number = 1,再次按下按键 number = 0
- 在按下按键的时候需要同时将 led1 的状态取反>
- 驱动中需要编写字符设备驱动
- 驱动中需要自动创建设备节点
- 在这个驱动需要的所有设备信息放在设备树的同一个节点中
Repo文章来源地址https://www.toymoban.com/news/detail-599427.html
设备树文件
/dts-v1/;
#include "stm32mp157.dtsi"
#include "stm32mp15xa.dtsi"
#include "stm32mp15-pinctrl.dtsi"
#include "stm32mp15xxac-pinctrl.dtsi"
#include "stm32mp15xx-fsmp1x.dtsi"
/ {
model = "HQYJ STM32MP157 FSMP1A Discovery Board";
compatible = "st,stm32mp157a-dk1", "st,stm32mp157";
aliases {
serial0 = &uart4;
serial5 = &usart3;
};
chosen {
stdout-path = "serial0:115200n8";
};
reserved-memory {
gpu_reserved: gpu@d4000000 {
reg = <0xd4000000 0x4000000>;
no-map;
};
optee_memory: optee@0xde000000 {
reg = <0xde000000 0x02000000>;
no-map;
};
};
//自定义设备树
mynode@0x12345678{
compatible = "hqyj,mynode";
astring="hello 23031";
uint =<0xaabbccdd 0x11223344>;
binarry=[00 0c 29 7b f9 be];
mixed ="hello",[11 22],<0x12345678>;
};
mychrdev {
led=<&gpioe 10 0>;
interrupt-parent=<&gpiof>;
interrupts=<9 0>;
};
};
驱动代码
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/of_irq.h>
#include <linux/of_gpio.h>
#include <linux/interrupt.h>
int major;
struct class *cls;
struct device *dev;
int number = 0;
unsigned int condition = 0;
wait_queue_head_t wq_head;
// 所有的设备都在同一个节点下
struct device_node *dnode;
unsigned int irqno;
struct gpio_desc *gpiono;
ssize_t mycdev_read(struct file *file, char *ubuf, size_t size, loff_t *lof)
{
int ret;
wait_event_interruptible(wq_head, condition);
ret = copy_to_user(ubuf, &number, sizeof(number));
if (ret) {
printk("copy_to_user failed\n");
return -EIO;
}
condition = 0;
return 0;
}
struct file_operations fops = {
.read = mycdev_read,
};
// 中断处理函数
irqreturn_t myirq_handler(int irq, void *dev_id)
{
number = !number;
gpiod_set_value(gpiono, number);
printk("key pressed, number=%d\n", number);
return IRQ_HANDLED;
}
static int __init mycdev_init(void)
{
int ret;
// 初始化等待队列头
init_waitqueue_head(&wq_head);
// 字符设备注册
major = register_chrdev(0, "mycdev", &fops);
if (major < 0) {
printk("register_chrdev failed\n");
return major;
}
// 向上提交目录
cls = class_create(THIS_MODULE, "mycdev");
if (IS_ERR(cls)) {
printk("class_create failed\n");
return -PTR_ERR(cls);
}
// 创建设备文件
dev = device_create(cls, NULL, MKDEV(major, 0), NULL, "led");
if (IS_ERR(dev)) {
printk("device_create failed\n");
return -PTR_ERR(dev);
}
dev = device_create(cls, NULL, MKDEV(major, 1), NULL, "key");
if (IS_ERR(dev)) {
printk("device_create failed\n");
return -PTR_ERR(dev);
}
dnode = of_find_node_by_path("/mychrdev");
if (!dnode) {
printk("of_find_node_by_path failed\n");
return -ENXIO;
}
irqno = irq_of_parse_and_map(dnode, 0);
if (!irqno) {
printk("irq_of_parse_and_map failed\n");
return -ENXIO;
}
ret = request_irq(irqno, myirq_handler, IRQF_TRIGGER_FALLING, "key",
NULL);
if (ret) {
printk("request_irq failed\n");
return ret;
}
gpiono = gpiod_get_from_of_node(dnode, "led", 0, GPIOD_OUT_LOW, NULL);
if (IS_ERR(gpiono)) {
printk("gpiod_get_from_of_node failed\n");
return -PTR_ERR(gpiono);
}
return 0;
}
static void __exit mycdev_exit(void)
{
// 注销设备文件
device_destroy(cls, MKDEV(major, 0));
device_destroy(cls, MKDEV(major, 1));
// 注销目录
class_destroy(cls);
// 注销字符设备
unregister_chrdev(major, "mycdev");
// 注销中断号
free_irq(irqno, NULL);
// 释放gpio
gpiod_put(gpiono);
}
module_init(mycdev_init);
module_exit(mycdev_exit);
MODULE_LICENSE("GPL");
测试代码
#include <stdlib.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <string.h>
#include <sys/ioctl.h>
int main(int argc, char const *argv[])
{
int number;
int fd = open("/dev/led", O_RDWR);
if (fd < 0) {
printf("打开设备文件失败\n");
exit(-1);
}
while (1) {
read(fd, &number, sizeof(number)); //读取数据
printf("read:%d\n", number);
}
close(fd);
return 0;
}
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