为什么我做出来的驱动无法使用echo对设备进行控制呢？

seven_spark

为什么我做出来的驱动无法使用echo对设备进行控制呢？ [复制链接]

我编写了一个LED的驱动程序，为什么我无法使用echo 的方式对该设备节点进行写呢？驱动模块的处理流程是在init中先alloc_chrdev_region后，使用cdev_init初始化cdev，然后使用cdev_add将file_operations的操作函数添加到字符设备中，再使用class_create和device_create。该流程有啥问题吗？有没有知道这原因的大佬帮忙指点一下。。

tagetage

我编写了一个LED的驱动程序，为什么我无法使用echo 的方式对该设备节点进行写呢？--------LED驱动？？不就是GPIO驱动吗？？  GPIO驱动不都是现成的嘛，，你自己写的话你参考linux开源代码怎么写的。

seven_spark

<i class="pstatus"> 本帖最后由 seven_spark 于 2024-7-28 10:20 编辑 </i> 就是GPIO的驱动，我没有参照现成的，没有使用设备树，为什么这种方式不行呢？ #include <linux/types.h> #include <linux/kernel.h> #include <linux/delay.h> #include <linux/ide.h> #include <linux/init.h> #include <linux/module.h> #include <linux/errno.h> #include <linux/gpio.h> #include <asm/mach/map.h> #include <asm/io.h> #include <linux/uaccess.h> #include <linux/cdev.h> #include <linux/device.h> /* 头文件，是与芯片物理属性相关的，寄存器值 */ #define CCM_CCGR1_BASE (0X020C406C) #define SW_MUX_GPIO1_IO03_BASE (0X020E0068) #define SW_PAD_GPIO1_IO03_BASE (0X020E02F4) #define GPIO1_DR_BASE (0X0209C000) #define GPIO1_GDIR_BASE (0X0209C004) /* 虚实映射的地址，是虚拟地址 */ static void __iomem *IMX6U_CCM_CCGR1; static void __iomem *SW_MUX_GPIO1_IO03; static void __iomem *SW_PAD_GPIO1_IO03; static void __iomem *GPIO1_DR; static void __iomem *GPIO1_GDIR; /* 宏定义 */ #define LED_NAME "led_us" #define LEDOFF 0 #define LEDON 1 #define LED_NUM 1 static struct led_st { int major; int minor; int num; char *name; dev_t devno; struct cdev cdev; struct class *cls; struct device *dvs; unsigned char buf[1]; }; static struct led_st *led = NULL; static void led_switch(unsigned char sta) { unsigned int val = 0; if(sta == LEDON) { val = readl(GPIO1_DR);//GPIO_DR是控制电平的寄存器 val &= ~(1 << 3); writel(val, GPIO1_DR); } else if(sta == LEDOFF) { val = readl(GPIO1_DR); val |= (1 << 3); writel(val, GPIO1_DR); } else { printk("please input valid value.\n"); } } static int led_open(struct inode *pinode, struct file *filp) { filp->private_data = (void*)(container_of(pinode->i_cdev, struct led_st, cdev)); return 0; } static ssize_t led_read(struct file *filp, char __user *buf, size_t cnt, loff_t *offt) { return 0; } static ssize_t led_write(struct file *pfilp, const char __user *buf, size_t cnt, loff_t *offt) { int retvalue; unsigned char ledstat; struct led_st *ptemp = (struct led_st *)pfilp->private_data; retvalue = copy_from_user(ptemp->buf, buf, cnt); if(retvalue < 0) { printk("kernel write failed.\n"); return -EFAULT; } ledstat = ptemp->buf[0]; if(ledstat == LEDON) { led_switch(LEDON); } else if(ledstat == LEDOFF) { led_switch(LEDOFF); } else { return -EFAULT; } *offt += cnt; return cnt; } static int led_release(struct inode *inode, struct file *filp) { return 0; } static struct file_operations led_fops = { .owner = THIS_MODULE, .open = led_open, .read = led_read, .write = led_write, .release = led_release, }; static int __init led_init(void) { int val = 0; led = kzalloc(sizeof(struct led_st), GFP_KERNEL); if(NULL == led) { printk("led kzalloc failed\n"); return -1; } else { led->major = 0; led->minor = 0; led->num = LED_NUM; led->name = LED_NAME; } IMX6U_CCM_CCGR1 = ioremap(CCM_CCGR1_BASE, 4); SW_MUX_GPIO1_IO03 = ioremap(SW_MUX_GPIO1_IO03_BASE, 4); SW_PAD_GPIO1_IO03 = ioremap(SW_PAD_GPIO1_IO03_BASE, 4); GPIO1_DR = ioremap(GPIO1_DR_BASE, 4); GPIO1_GDIR = ioremap(GPIO1_GDIR_BASE, 4); val = readl(IMX6U_CCM_CCGR1); val &= ~(3 << 26); val |= (3 << 26); writel(val, IMX6U_CCM_CCGR1); writel(5, SW_MUX_GPIO1_IO03); writel(0x10b0, SW_PAD_GPIO1_IO03); val = readl(GPIO1_GDIR); val &= ~(1 << 3); val |= (1 << 3); writel(val, GPIO1_GDIR); val = readl(GPIO1_DR); val |= (1 << 3); writel(val, GPIO1_DR); if(alloc_chrdev_region(&(led->devno), 0, led->num, led->name)) { printk("alloc chrdev region failed\n"); return -1; } else { cdev_init(&(led->cdev), &led_fops); if(cdev_add(&(led->cdev), led->devno, led->num)) { unregister_chrdev_region(led->devno, led->num); printk("cdev add failed\n"); return -2; } } led->cls = class_create(THIS_MODULE, led->name); if(led->cls == NULL) { printk("class create failed\n"); cdev_del(&(led->cdev)); unregister_chrdev_region(led->devno, led->num); return -3; } led->dvs = device_create(led->cls, NULL, led->devno, NULL, led->name); if(led->dvs == NULL) { printk("device create failed\n"); class_destroy(led->cls); cdev_del(&(led->cdev)); unregister_chrdev_region(led->devno, led->num); return -4; } return 0; } static void __exit led_exit(void) { iounmap(IMX6U_CCM_CCGR1); iounmap(SW_MUX_GPIO1_IO03); iounmap(SW_PAD_GPIO1_IO03); iounmap(GPIO1_DR); iounmap(GPIO1_GDIR); device_destroy(led->cls, led->devno); class_destroy(led->cls); cdev_del(&(led->cdev)); unregister_chrdev_region(led->devno, led->num); led = NULL; } module_init(led_init); module_exit(led_exit); MODULE_LICENSE("GPL");