Linux驱动开发之混杂设备驱动代码实例
1、平台设备 #include <linux/module.h> #include <linux/types.h> #include <linux/fs.h> #include <linux/init.h> #include <linux/platform_device.h> #include <asm/arch/regs-gpio.h> #include <linux/interrupt.h> #include <linux/device.h> #include <linux/io.h> /*平台资源的定义*/ static struct resource s3c_buttons_resource[] = { [0]={ .start = S3C24XX_PA_GPIO, .end = S3C24XX_PA_GPIO + S3C24XX_SZ_GPIO - 1, .flags = IORESOURCE_MEM, //IO内存 }, [1]={ .start = IRQ_EINT0, //注册外部中断0的中断号 .end = IRQ_EINT0, .flags = IORESOURCE_IRQ, }, [2]={ .start = IRQ_EINT2, //注册外部中断2的中断号 .end = IRQ_EINT2, .flags = IORESOURCE_IRQ, }, [3]={ .start = IRQ_EINT11, //注册外部中断11的中断号 .end = IRQ_EINT11, .flags = IORESOURCE_IRQ, }, [4]={ .start = IRQ_EINT19, //注册外部中断19的中断号 .end = IRQ_EINT19, .flags = IORESOURCE_IRQ, } }; static struct platform_device s3c_buttons = { .name = "s3c2440-buttons", //设备的名称 .id = 0, .num_resources = ARRAY_SIZE(s3c_buttons_resource), //资源数量 .resource = s3c_buttons_resource, //注册到内核中的资源 }; static int __init platform_init(void) { /*平台设备的注册*/ platform_device_register(&s3c_buttons); return 0; } static void __exit platform_exit(void) { platform_device_unregister(&s3c_buttons); //注销设备 } module_init(platform_init); module_exit(platform_exit); MODULE_LICENSE("GPL"); MODULE_ALIAS("platform:s3c2440buttons"); 2、平台驱动 #include <linux/module.h> #include <linux/types.h> #include <linux/miscdevice.h> #include <linux/fs.h> #include <linux/init.h> #include <linux/platform_device.h> #include <linux/interrupt.h> #include <linux/clk.h> #include <linux/uaccess.h> #include <linux/io.h> #include <asm/arch/regs-gpio.h> #include <linux/poll.h> #include <linux/irq.h> #include <asm/unistd.h> #include <linux/device.h> static DECLARE_WAIT_QUEUE_HEAD(button_waitq); static volatile int ev_press = 0; static int key_value; static struct device *buttons_dev; /* platform device attached to */ static struct resource *buttons_mem; static struct resource *buttons_irq; static void __iomem *buttons_base; static int button_irqs[4]; //中断处理函数 static irqreturn_t buttons_interrupt(int irq, void *dev_id) { int i; for(i=0; i<4; i++){ if(irq == button_irqs[i]){ //printk("==>interrput number:%d\n",irq); key_value = i; //根据中断号获得键值 ev_press =1; //标志位置1 wake_up_interruptible(&button_waitq);//在中断里面把读进程唤醒 } } return IRQ_RETVAL(IRQ_HANDLED); } static int s3c24xx_buttons_open(struct inode *inode, struct file *file) { int i; int err = 0; /*注册中断*/ for(i=0; i<4; i++){ if (button_irqs[i] < 0) continue; /*中断触发方式:上升沿触发*/ err = request_irq(button_irqs[i],buttons_interrupt,IRQ_TYPE_EDGE_RISING,NULL,NULL); if(err) break; } if (err) { i--; for (; i >= 0; i--) { if (button_irqs[i] < 0) { continue; } disable_irq(button_irqs[i]); free_irq(button_irqs[i], NULL); } return -EBUSY; } ev_press = 0; return 0; } static int s3c24xx_buttons_close(struct inode *inode, struct file *file) { int i; for (i=0; i<4; i++) { if (button_irqs[i] < 0) { continue; } free_irq(button_irqs[i],NULL); //注销中断 } return 0; } static int s3c24xx_buttons_read(struct file *filp, char __user *buff, size_t count, loff_t *offp) { unsigned long err; if (!ev_press) { if (filp->f_flags & O_NONBLOCK) //判断是否是非阻塞读 return -EAGAIN; else wait_event_interruptible(button_waitq, ev_press);//阻塞读 } ev_press = 0; //把标志位清零 err = copy_to_user(buff, &key_value, sizeof(key_value));//把键值传给用户 return sizeof(key_value); } static unsigned int s3c24xx_buttons_poll( struct file *file, struct poll_table_struct *wait) { unsigned int mask = 0; poll_wait(file, &button_waitq, wait);//把等待队列添加到poll_table_struct if (ev_press){ //标志位,中断控制的 mask |= POLLIN | POLLRDNORM; } return mask; } static struct file_operations s3c2440buttons_fops = { .owner = THIS_MODULE, .open = s3c24xx_buttons_open, .release = s3c24xx_buttons_close, .read = s3c24xx_buttons_read, .poll = s3c24xx_buttons_poll, }; static struct miscdevice s3c2440_miscdev = { .minor = MISC_DYNAMIC_MINOR, //自动分配混杂设备的次设备号 .name ="buttons", //设备名字 .fops = &s3c2440buttons_fops, }; /* device interface */ static int s3c2440_buttons_probe(struct platform_device *pdev) { struct resource *res; struct device *dev; int ret; int size; int i; printk("probe:%s\n", __func__); dev = &pdev->dev; buttons_dev = &pdev->dev; /*平台资源获取*/ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);//获得平台设备注册的IO内存资源 if (res == NULL) { dev_err(dev, "no memory resource specified\n"); return -ENOENT; } size = (res->end - res->start) + 1; //计算IO内存资源的大小 buttons_mem = request_mem_region(res->start, size, pdev->name);//申请IO内存资源 if (buttons_mem == NULL) { dev_err(dev, "failed to get memory region\n"); ret = -ENOENT; goto err_req; } buttons_base = ioremap(res->start, size);//把物理地址映射为虚拟地址 返回值为虚拟地址 if (buttons_base == NULL) { dev_err(dev, "failed to ioremap() region\n"); ret = -EINVAL; goto err_req; } printk(KERN_DEBUG"probe: mapped buttons_base=%p\n", buttons_base); /*get irq number*/ for(i=0; i<4; i++){ //获取中断号 buttons_irq = platform_get_resource(pdev,IORESOURCE_IRQ,i);//获得平台设备注册的中断资源 if(buttons_irq == NULL){ dev_err(dev,"no irq resource specified\n"); ret = -ENOENT; goto err_map; } button_irqs[i] = buttons_irq->start; //中断资源里面获得中断号 //printk("button_irqs[%d]=%d\n",i,button_irqs[i]); } ret = misc_register(&s3c2440_miscdev); //注册混杂设备 return 0; err_map: iounmap(buttons_base); //解除映射 err_req: release_resource(buttons_mem); kfree(buttons_mem); return ret; } static int s3c2440_buttons_remove(struct platform_device *dev)//平台驱动移除的时候调用 { iounmap(buttons_base); //解除映射 misc_deregister(&s3c2440_miscdev); //注销混杂设备 release_resource(buttons_mem); //注销资源 kfree(buttons_mem); buttons_mem = NULL; return 0; } /*平台驱动定义*/ static struct platform_driver s3c2440buttons_driver = { .probe = s3c2440_buttons_probe, //平台设备和驱动匹配的时候调用 .remove = s3c2440_buttons_remove, //平台驱动移除的时候调用 .driver = { .owner = THIS_MODULE, .name = "s3c2440-buttons", //平台驱动的名称 }, }; static char banner[] __initdata = "s3c2440 Buttons Driver\n"; static int __init buttons_init(void) { printk(banner); /*平台驱动注册*/ platform_driver_register(&s3c2440buttons_driver); return 0; } static void __exit buttons_exit(void) { platform_driver_unregister(&s3c2440buttons_driver); } module_init(buttons_init); module_exit(buttons_exit); MODULE_DESCRIPTION("s3c2440 Buttons Driver"); MODULE_LICENSE("GPL"); 3、应用程序 #include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <sys/ioctl.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #include <sys/select.h> #include <sys/time.h> #include <errno.h> int main(void) { int buttons_fd=0; int key_value; buttons_fd = open("dev/buttons",O_RDWR);//打开设备文件 if (buttons_fd < 0) { perror("open device buttons"); exit(1); } for (;;) { fd_set rds; //读文件描述符集 int ret; FD_ZERO(&rds); //清空读文件描述符集 FD_SET(buttons_fd, &rds); //把读文件描述符添加到文件描述符集 ret = select(buttons_fd + 1, &rds, NULL, NULL, NULL);//条件不满足阻塞 if (ret < 0) { perror("select"); exit(1); } if (ret == 0) { printf("Timeout.\n"); } else if (FD_ISSET(buttons_fd, &rds)) {//判断文件是否可读 int ret = read(buttons_fd, &key_value, sizeof(key_value)); if (ret != sizeof(key_value)) { if (errno != EAGAIN) perror("read buttons\n"); continue; } else { printf("buttons_value: %d\n", key_value+1); } } } close(buttons_fd); return 0; }