工作队列是在内核的线程的上下文中执行的
工作队列中有多个 work,前一个 work 没处理完会影响后面的 work。解决方法有如下2种:
比如自己创建一个内核线程,不跟别的 work 在一块。例如存储设备比如 SD/TF采用的就是单独一个线程。
使用线程化的中断处理。中断的处理仍然可以认为分为上半部、下半部。上半部用来处理紧急的事情,下半部用一个内核线程来处理,这个内核线程专用于这个中断。
只需要提供 thread_fn,系统会为这个函数创建一个内核线程。发生中断时,系统会立刻调用 handler 函数,然后唤醒某个内核线程,内核线程再来执行 thread_fn 函数。
调用 request_threaded_irq
函数注册中断,调用 free_irq
卸载中断。
request_threaded_irq可以提供上半部函数,也可以不提供
IRQ_WAKE_THREAD
。在 thread_fn 中,如果中断被正确处理了,应该返回 IRQ_HANDLED
。
#include
#include
#include
#include
#include
#include
#include
#include
static int fd;
/*
* ./button_test /dev/my_button0 &
*
*/
int main(int argc, char **argv)
{
int val;
struct pollfd fds[1];
int timeout_ms = 5000;
int ret;
int flags;
int i;
/* 1. 判断参数 */
if (argc != 2)
{
printf("Usage: %s \n" , argv[0]);
return -1;
}
/* 2. 打开文件 */
fd = open(argv[1], O_RDWR | O_NONBLOCK);
if (fd == -1)
{
printf("can not open file %s\n", argv[1]);
return -1;
}
for (i = 0; i < 10; i++)
{
if (read(fd, &val, 4) == 4)
printf("get button: 0x%x\n", val);
else
printf("get button: -1\n");
}
flags = fcntl(fd, F_GETFL);
fcntl(fd, F_SETFL, flags & ~O_NONBLOCK);
while (1)
{
if (read(fd, &val, 4) == 4)
printf("get button: 0x%x\n", val);
else
printf("while get button: -1\n");
}
close(fd);
return 0;
}
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include //打印内核线程的id需要的头文件
struct gpio_key{
int gpio;
struct gpio_desc *gpiod;
int flag;
int irq;
struct timer_list key_timer;
struct tasklet_struct tasklet;
struct work_struct work;//每个按键都有工作队列
} ;
static struct gpio_key *gpio_keys_first;
/* 主设备号 */
static int major = 0;
static struct class *gpio_key_class;
/* 环形缓冲区 */
#define BUF_LEN 128
static int g_keys[BUF_LEN];
static int r, w;
struct fasync_struct *button_fasync;
#define NEXT_POS(x) ((x+1) % BUF_LEN)
static int is_key_buf_empty(void)
{
return (r == w);
}
static int is_key_buf_full(void)
{
return (r == NEXT_POS(w));
}
static void put_key(int key)
{
if (!is_key_buf_full())
{
g_keys[w] = key;
w = NEXT_POS(w);
}
}
static int get_key(void)
{
int key = 0;
if (!is_key_buf_empty())
{
key = g_keys[r];
r = NEXT_POS(r);
}
return key;
}
static DECLARE_WAIT_QUEUE_HEAD(gpio_key_wait);
static void key_timer_expire(struct timer_list *t)
{
struct gpio_key *gpio_key = from_timer(gpio_key, t, key_timer);
int val;
int key;
val = gpiod_get_value(gpio_key->gpiod);
printk("key_timer_expire key %d %d\n", gpio_key->gpio, val);
key = (gpio_key->gpio << 8) | val;
put_key(key);
wake_up_interruptible(&gpio_key_wait);
kill_fasync(&button_fasync, SIGIO, POLL_IN);
}
static void key_tasklet_func(unsigned long data)
{
/* data ==> gpio */
struct gpio_key *gpio_key = data;
int val;
int key;
val = gpiod_get_value(gpio_key->gpiod);
printk("key_tasklet_func key %d %d\n", gpio_key->gpio, val);
}
static void key_work_func(struct work_struct *work)
{
struct gpio_key *gpio_key = container_of(work, struct gpio_key, work);//根据work成员的地址反推结构体地址
int val;
val = gpiod_get_value(gpio_key->gpiod);
printk("key_work_func: the process is %s pid %d\n",current->comm, current->pid);//打印内核线程的id
printk("key_work_func key %d %d\n", gpio_key->gpio, val);
}
/* 实现对应的open/read/write等函数,填入file_operations结构体 */
static ssize_t gpio_key_drv_read (struct file *file, char __user *buf, size_t size, loff_t *offset)
{
//printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
int err;
int key;
if (is_key_buf_empty() && (file->f_flags & O_NONBLOCK))
return -EAGAIN;
wait_event_interruptible(gpio_key_wait, !is_key_buf_empty());
key = get_key();
err = copy_to_user(buf, &key, 4);
return 4;
}
static unsigned int gpio_key_drv_poll(struct file *fp, poll_table * wait)
{
printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
poll_wait(fp, &gpio_key_wait, wait);
return is_key_buf_empty() ? 0 : POLLIN | POLLRDNORM;
}
static int gpio_key_drv_fasync(int fd, struct file *file, int on)
{
if (fasync_helper(fd, file, on, &button_fasync) >= 0)
return 0;
else
return -EIO;
}
/* 定义自己的file_operations结构体 */
static struct file_operations gpio_key_drv = {
.owner = THIS_MODULE,
.read = gpio_key_drv_read,
.poll = gpio_key_drv_poll,
.fasync = gpio_key_drv_fasync,
};
static irqreturn_t gpio_key_isr(int irq, void *dev_id)
{
struct gpio_key *gpio_key = dev_id;
//printk("gpio_key_isr key %d irq happened\n", gpio_key->gpio);
tasklet_schedule(&gpio_key->tasklet);
mod_timer(&gpio_key->key_timer, jiffies + HZ/50);
schedule_work(&gpio_key->work);
return IRQ_WAKE_THREAD;//指定上半部分函数返回值指定为:IRQ_WAKE_THREAD
}
static irqreturn_t gpio_key_thread_func(int irq, void *data)
{
struct gpio_key *gpio_key = data;
int val;
val = gpiod_get_value(gpio_key->gpiod);
printk("gpio_key_thread_func: the process is %s pid %d\n",current->comm, current->pid); //打印线程id
printk("gpio_key_thread_func key %d %d\n", gpio_key->gpio, val);
return IRQ_HANDLED;//指定下半部分函数返回值指定为:IRQ_WAKE_THREAD
}
/* 1. 从platform_device获得GPIO
* 2. gpio=>irq
* 3. request_irq
*/
static int gpio_key_probe(struct platform_device *pdev)
{
int err;
struct device_node *node = pdev->dev.of_node;
int count;
int i;
enum of_gpio_flags flag;
printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
count = of_gpio_count(node);
if (!count)
{
printk("%s %s line %d, there isn't any gpio available\n", __FILE__, __FUNCTION__, __LINE__);
return -1;
}
gpio_keys_first= kzalloc(sizeof(struct gpio_key) * count, GFP_KERNEL);
for (i = 0; i < count; i++)
{
gpio_keys_first[i].gpio = of_get_gpio_flags(node, i, &flag);
if (gpio_keys_first[i].gpio < 0)
{
printk("%s %s line %d, of_get_gpio_flags fail\n", __FILE__, __FUNCTION__, __LINE__);
return -1;
}
gpio_keys_first[i].gpiod = gpio_to_desc(gpio_keys_first[i].gpio);
gpio_keys_first[i].flag = flag & OF_GPIO_ACTIVE_LOW;
gpio_keys_first[i].irq = gpio_to_irq(gpio_keys_first[i].gpio);
//setup_timer(&gpio_keys_first[i].key_timer, key_timer_expire, &gpio_keys_first[i]);
timer_setup(&gpio_keys_first[i].key_timer, key_timer_expire, 0);
gpio_keys_first[i].key_timer.expires = ~0;
add_timer(&gpio_keys_first[i].key_timer);
tasklet_init(&gpio_keys_first[i].tasklet, key_tasklet_func, &gpio_keys_first[i]);
INIT_WORK(&gpio_keys_first[i].work, key_work_func);//初始化工作队列
}
for (i = 0; i < count; i++)
{
//err = request_irq(gpio_keys_first[i].irq, gpio_key_isr, IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING, "my_gpio_key", &gpio_keys_first[i]);
err = request_threaded_irq(gpio_keys_first[i].irq, gpio_key_isr, gpio_key_thread_func, IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING, "my_gpio_key", &gpio_keys_first[i]);
}
/* 注册file_operations */
major = register_chrdev(0, "my_gpio_key", &gpio_key_drv); /* /dev/gpio_key */
gpio_key_class = class_create(THIS_MODULE, "my_gpio_key_class");
if (IS_ERR(gpio_key_class)) {
printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
unregister_chrdev(major, "my_gpio_key");
return PTR_ERR(gpio_key_class);
}
device_create(gpio_key_class, NULL, MKDEV(major, 0), NULL, "my_gpio_key"); /* /dev/my_gpio_key */
return 0;
}
static int gpio_key_remove(struct platform_device *pdev)
{
//int err;
struct device_node *node = pdev->dev.of_node;
int count;
int i;
device_destroy(gpio_key_class, MKDEV(major, 0));
class_destroy(gpio_key_class);
unregister_chrdev(major, "my_gpio_key");
count = of_gpio_count(node);
for (i = 0; i < count; i++)
{
free_irq(gpio_keys_first[i].irq, &gpio_keys_first[i]);
del_timer(&gpio_keys_first[i].key_timer);
tasklet_kill(&gpio_keys_first[i].tasklet);
}
kfree(gpio_keys_first);
return 0;
}
static const struct of_device_id my_keys[] = {
{ .compatible = "first_key,gpio_key" },
{ },
};
/* 1. 定义platform_driver */
static struct platform_driver gpio_keys_driver = {
.probe = gpio_key_probe,
.remove = gpio_key_remove,
.driver = {
.name = "my_gpio_key",
.of_match_table = my_keys,
},
};
/* 2. 在入口函数注册platform_driver */
static int __init gpio_key_init(void)
{
int err;
printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
err = platform_driver_register(&gpio_keys_driver);
return err;
}
/* 3. 有入口函数就应该有出口函数:卸载驱动程序时,就会去调用这个出口函数
* 卸载platform_driver
*/
static void __exit gpio_key_exit(void)
{
printk("%s %s line %d\n", __FILE__, __FUNCTION__, __LINE__);
platform_driver_unregister(&gpio_keys_driver);
}
/* 7. 其他完善:提供设备信息,自动创建设备节点 */
module_init(gpio_key_init);
module_exit(gpio_key_exit);
MODULE_LICENSE("GPL");
# 1. 使用不同的开发板内核时, 一定要修改KERN_DIR
# 2. KERN_DIR中的内核要事先配置、编译, 为了能编译内核, 要先设置下列环境变量:
# 2.1 ARCH, 比如: export ARCH=arm64
# 2.2 CROSS_COMPILE, 比如: export CROSS_COMPILE=aarch64-linux-gnu-
# 2.3 PATH, 比如: export PATH=$PATH:/home/book/100ask_roc-rk3399-pc/ToolChain-6.3.1/gcc-linaro-6.3.1-2017.05-x86_64_aarch64-linux-gnu/bin
# 注意: 不同的开发板不同的编译器上述3个环境变量不一定相同,
# 请参考各开发板的高级用户使用手册
KERN_DIR = /home/book/100ask_stm32mp157_pro-sdk/Linux-5.4
all:
make -C $(KERN_DIR) M=`pwd` modules
$(CROSS_COMPILE)gcc -o button_test button_test.c
clean:
make -C $(KERN_DIR) M=`pwd` modules clean
rm -rf modules.order button_test
# 参考内核源码drivers/char/ipmi/Makefile
# 要想把a.c, b.c编译成ab.ko, 可以这样指定:
# ab-y := a.o b.o
# obj-m += ab.o
obj-m += gpio_key_drv.o
对于一个引脚要用作中断时,
打开内核的设备树文件:arch/arm/boot/dts/stm32mp157c-100ask-512d-lcd-v1.dts
gpio_keys_first {
compatible = "first_key,gpio_key";
gpios = <&gpiog 3 GPIO_ACTIVE_LOW
&gpiog 2 GPIO_ACTIVE_LOW>;
};
与此同时,需要把用到引脚的节点禁用
注意,如果其他设备树文件也用到该节点,需要设置属性为disabled状态,在arch/arm/boot/dts目录下执行如下指令查找哪些设备树用到该节点
grep "&gpiog" * -nr
如果用到该节点,需要添加属性去屏蔽:
status = "disabled";
首先要设置 ARCH、CROSS_COMPILE、PATH 这三个环境变量后,进入 ubuntu 上板子内核源码的目录,在Linux内核源码根目录下,执行如下命令即可编译 dtb 文件:
make dtbs V=1
编译好的文件在路径由DTC指定,移植设备树到开发板的共享文件夹中,先保存源文件,然后覆盖源文件,重启后会挂载新的设备树,进入该目录查看是否有新添加的设备节点
cd /sys/firmware/devicetree/base
编译驱动程序,在Makefile文件目录下执行make指令,此时,目录下有编译好的内核模块gpio_key_drv.ko和可执行文件button_test文件移植到开发板上
确定一下烧录系统:cat /proc/mounts
,查看boot分区挂载的位置,将其重新挂载在boot分区:mount /dev/mmcblk2p2 /boot
,然后将共享文件夹里面的设备树文件拷贝到boot目录下,这样的话设备树文件就在boot目录下
cp /mnt/stm32mp157c-100ask-512d-lcd-v1.dtb /boot
重启后挂载,运行
insmod -f gpio_key_drv.ko // 强制安装驱动程序
ls /dev/my_gpio_key
./button_test /dev/my_gpio_key & //后台运行,此时prink函数打印的内容看不到
然后按下按键