字符设备支持单驱动多设备.

Signed-off-by: ithink.chan <chenyang@autoai.com>

Linux/KernelDriver/3.2/Char/demo_char.c

@@ -32,15 +32,17 @@ MODULE_LICENSE("GPL");
 #define DEMO_CTL_MAX    5
 #define DEMO_MODULE_NAME    "demo_char"
 
+#define DEMO_DEV_CNT    2
+
 static int demo_major = 0;
 
 struct demo_dev
 {
     struct cdev cdev;
-    struct class *uclass;
+    struct device *dev;
-    struct device *udevice;
 };
 
+struct class *class;
 struct demo_dev* demo_devp;
 
 static int demo_open(struct inode *inode, struct file* filp)
@@ -149,57 +151,88 @@ static struct file_operations demo_fops = {
     .mmap           = demo_mmap
 };
 
+static int demo_setup_cdev(struct demo_dev *devp, int index)
+{
+    char name[16];
+    int err, devno = MKDEV(demo_major, index);
+
+    cdev_init(&devp->cdev, &demo_fops);
+    devp->cdev.owner = THIS_MODULE;
+    devp->cdev.ops = &demo_fops;
+    err = cdev_add(&devp->cdev, devno, 1);
+    if(err)
+    {
+        printk(KERN_ERR "Error(%d) %d.\r\n", index, err);
+        goto out_cdev;
+    }
+
+    memset(name, 0, 16);
+    sprintf(name, DEMO_MODULE_NAME"%d", index);
+    printk(KERN_INFO "New dev name:%s", name);
+    devp->dev = device_create(class, NULL, devp->cdev.dev, NULL, name);
+    return 0;
+out_cdev:
+    cdev_del(&devp->cdev);
+    kfree(devp);
+    return err;
+}
+
 static int __init demo_init(void)
 {
-    int result;
+    int err, i;
     dev_t devno = MKDEV(demo_major, 0);
 
     if(demo_major)
-        result = register_chrdev_region(devno, 1, DEMO_MODULE_NAME);
+        err = register_chrdev_region(devno, DEMO_DEV_CNT, DEMO_MODULE_NAME);
     else
     {
-        result = alloc_chrdev_region(&devno, 0, 1, DEMO_MODULE_NAME);
+        err = alloc_chrdev_region(&devno, 0, DEMO_DEV_CNT, DEMO_MODULE_NAME);
         demo_major = MAJOR(devno);
     }
 
-    if(result < 0)
+    if(err<0)
-        return result;
+        return err;
 
-    demo_devp = kzalloc(sizeof(struct demo_dev), GFP_KERNEL);
+    demo_devp = kzalloc(DEMO_DEV_CNT*sizeof(struct demo_dev), GFP_KERNEL);
     if(!demo_devp)
     {
-        result = - ENOMEM;
+        err = -ENOMEM;
-        goto out_kmalloc;
+        goto out;
     }
 
-    cdev_init(&demo_devp->cdev, &demo_fops);
+    class = class_create(THIS_MODULE, DEMO_MODULE_NAME);
-    demo_devp->cdev.owner = THIS_MODULE;
+    for(i=0; i<DEMO_DEV_CNT; i++)
-    demo_devp->cdev.ops = &demo_fops;
-    result = cdev_add(&demo_devp->cdev, devno, 1);
-    if(result)
     {
-        printk(KERN_NOTICE "Error %d.\r\n", result);
+        err = demo_setup_cdev(&demo_devp[i], i);
-        goto out_cdev;
+        if(err)
+            goto out_class;
     }
-    demo_devp->uclass = class_create(THIS_MODULE, DEMO_MODULE_NAME);
-    demo_devp->udevice = device_create(demo_devp->uclass, NULL, demo_devp->cdev.dev, NULL, DEMO_MODULE_NAME"0");
 
     return 0;
-out_cdev:
+
-    cdev_del(&demo_devp->cdev);
+out_class:
-    kfree(demo_devp);
+    class_destroy(class);
-out_kmalloc:
+out:
-    unregister_chrdev_region(devno, 1);
+    unregister_chrdev_region(devno, DEMO_DEV_CNT);
-    return result;
+    return err;
+}
+
+static void demo_clean_cdev(struct demo_dev *devp)
+{
+    device_destroy(class, devp->cdev.dev);
+    cdev_del(&devp->cdev);
 }
 
 static void __exit demo_exit(void)
 {
-    device_destroy(demo_devp->uclass, demo_devp->cdev.dev);
+    int i;
-    class_destroy(demo_devp->uclass);
+
-    cdev_del(&demo_devp->cdev);
+    for(i=0; i<DEMO_DEV_CNT; i++)
+        demo_clean_cdev(&demo_devp[i]);
+
+    class_destroy(class);
     kfree(demo_devp);
-    unregister_chrdev_region(MKDEV(demo_major, 0), 1);
+    unregister_chrdev_region(MKDEV(demo_major, 0), DEMO_DEV_CNT);
 }
 
 module_param(demo_major, int, S_IRUGO);

Linux/KernelDriver/3.2/Misc/demo_misc.c

@@ -1,23 +1,8 @@
 /**
- * @file    demo_misc.c
+ * @file    demo_char.c
  * @author  Rick Chan (cy187lion@sina.com)
- * @brief   Linux misc driver demo.
+ * @brief   Linux char driver demo.
-            在 Linux 驱动中，会把一些无法归类的设备定义为混杂设备，它们是拥
+ * @version 0.1.0
-            有着共同的特性的简单字符设备。它们的特点是共享统一的主设备号 10，
-            但每个设备可以选择一个单独的次设备号。
-
-            通常情况下，一个字符设备都不得不在初始化的过程中进行下面的步骤：
-
-            1.通过alloc_chrdev_region()分配主/次设备号
-            2.使用cdev_init()和cdev_add()来以一个字符设备注册自己
-
-            而一个misc驱动，则可以只用一个调用misc_register()来完成这所有
-            的步骤。
-
-            所有的 miscdevice 设备形成一个链表，对设备访问时，内核根据次设
-            备号查找对应的 miscdevice 设备，然后调用其 file_operations 
-            中注册的文件操作方法进行操作。
- * @version 0.1.1
  * @date    2020-04-27
  * 
  * @copyright Copyright (c) 2020
@@ -30,6 +15,10 @@
 #include <linux/uaccess.h>
 #include <linux/fs.h>
 
+#include <linux/cdev.h>
+#include <linux/slab.h>
+#include <linux/device.h>
+
 MODULE_AUTHOR("Rick Chan");
 MODULE_LICENSE("GPL");
 
@@ -41,9 +30,27 @@ MODULE_LICENSE("GPL");
 #define DEMO_CTL_IOW   _IOW(DEMO_MAGIC, 3, int32_t)
 #define DEMO_CTL_IOWR  _IOWR(DEMO_MAGIC, 4, uint32_t)
 #define DEMO_CTL_MAX    5
+#define DEMO_MODULE_NAME    "demo_char"
+
+#define DEMO_DEV_CNT    2
+
+static int demo_major = 0;
+
+struct demo_dev
+{
+    struct cdev cdev;
+    struct device *dev;
+};
+
+struct class *class;
+struct demo_dev* demo_devp;
 
 static int demo_open(struct inode *inode, struct file* filp)
 {
+    struct demo_dev *demo;
+    demo = container_of(inode->i_cdev, struct demo_dev, cdev);
+    filp->private_data = demo;
+
     return 0;
 }
 
@@ -54,41 +61,41 @@ static int demo_release(struct inode *inode, struct file* filp)
 
 static loff_t demo_llseek(struct file *filp, loff_t offset, int origin)
 {
+    struct demo_dev *devp = filp->private_data;
+
+    (void)devp;
     return filp->f_pos;
 }
 
 static ssize_t demo_read(struct file *filp, char __user *buffer, size_t count, loff_t *offset)
 {
+    struct demo_dev *devp = filp->private_data;
     const char __user *p = buffer;
+
+    (void)devp;
     return p-buffer;
 }
 
 static ssize_t demo_write(struct file *filp, const char __user *buffer, size_t count, loff_t *offset)
 {
+    struct demo_dev *devp = filp->private_data;
     const char __user *p = buffer;
+
+    (void)devp;
     return p-buffer;
 }
 
 static long demo_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 {
-    static int err = 0;
+    struct demo_dev *devp = filp->private_data;
+    (void)devp;
 
-    // 检测 cmd 合法性.
+    // 检测 cmd 合法性
     if (DEMO_MAGIC!=_IOC_TYPE(cmd)) 
         return -EINVAL;
     if (DEMO_CTL_MAX<_IOC_NR(cmd)) 
         return -EINVAL;
 
-    // 根据命令类型, 检测参数空间是否可以访问.
-    if(_IOC_DIR(cmd)&_IOC_READ)
-        err = !access_ok(VERIFY_WRITE, (void *)arg, _IOC_SIZE(cmd));
-    else if(_IOC_DIR(cmd)&_IOC_WRITE)
-        err = !access_ok(VERIFY_READ, (void *)arg, _IOC_SIZE(cmd));
-
-    if (err) 
-        return -EFAULT;
-
-    // 根据命令, 来选择执行哪个分支.
     switch(cmd)
     {
     case DEMO_CTL_IOC:
@@ -127,6 +134,9 @@ static long demo_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 
 static int demo_mmap(struct file* filp, struct vm_area_struct* vma)
 {
+    struct demo_dev *devp = filp->private_data;
+    (void)devp;
+
     return 0;
 }
 
@@ -141,22 +151,91 @@ static struct file_operations demo_fops = {
     .mmap           = demo_mmap
 };
 
-static struct miscdevice demo_dev = {
+static int demo_setup_cdev(struct demo_dev *devp, int index)
-    .minor  = MISC_DYNAMIC_MINOR,   // Dynamically allocate minor.
+{
-    .name   = "demo_misc",
+    char name[16];
-    .fops   = &demo_fops,
+    int err, devno = MKDEV(demo_major, index);
-};
+
+    cdev_init(&devp->cdev, &demo_fops);
+    devp->cdev.owner = THIS_MODULE;
+    devp->cdev.ops = &demo_fops;
+    err = cdev_add(&devp->cdev, devno, 1);
+    if(err)
+    {
+        printk(KERN_ERR "Error(%d) %d.\r\n", index, err);
+        goto out_cdev;
+    }
+
+    memset(name, 0, 16);
+    sprintf(name, DEMO_MODULE_NAME"%d", index);
+    printk(KERN_INFO "New dev name:%s", name);
+    devp->dev = device_create(class, NULL, devp->cdev.dev, NULL, name);
+    return 0;
+out_cdev:
+    cdev_del(&devp->cdev);
+    kfree(devp);
+    return err;
+}
 
 static int __init demo_init(void)
 {
-    misc_register(&demo_dev);   // 注册混杂设备驱动.
+    int err, i;
+    dev_t devno = MKDEV(demo_major, 0);
+
+    if(demo_major)
+        err = register_chrdev_region(devno, DEMO_DEV_CNT, DEMO_MODULE_NAME);
+    else
+    {
+        err = alloc_chrdev_region(&devno, 0, DEMO_DEV_CNT, DEMO_MODULE_NAME);
+        demo_major = MAJOR(devno);
+    }
+
+    if(err<0)
+        return err;
+
+    demo_devp = kzalloc(DEMO_DEV_CNT*sizeof(struct demo_dev), GFP_KERNEL);
+    if(!demo_devp)
+    {
+        err = -ENOMEM;
+        goto out;
+    }
+
+    class = class_create(THIS_MODULE, DEMO_MODULE_NAME);
+    for(i=0; i<DEMO_DEV_CNT; i++)
+    {
+        err = demo_setup_cdev(&demo_devp[i], i);
+        if(err)
+            goto out_class;
+    }
+
     return 0;
+
+out_class:
+    class_destroy(class);
+out:
+    unregister_chrdev_region(devno, DEMO_DEV_CNT);
+    return err;
+}
+
+static void demo_clean_cdev(struct demo_dev *devp)
+{
+    device_destroy(class, devp->cdev.dev);
+    cdev_del(&devp->cdev);
 }
 
 static void __exit demo_exit(void)
 {
-    misc_deregister(&demo_dev); // 撤销混杂设备驱动.
+    int i;
+
+    for(i=0; i<DEMO_DEV_CNT; i++)
+        demo_clean_cdev(&demo_devp[i]);
+
+    class_destroy(class);
+    kfree(demo_devp);
+    unregister_chrdev_region(MKDEV(demo_major, 0), DEMO_DEV_CNT);
 }
 
+module_param(demo_major, int, S_IRUGO);
+
 module_init(demo_init);
 module_exit(demo_exit);