使用Gadget 做usb鼠标键盘设备

使用Gadget 做usb鼠标键盘设备

感谢TI社区提供的好帮助啊！http://e2e.ti.com/support/arm/sitara_arm/f/791/p/571771/2103409?pi316653=2
虽然海思平台和TI平台不一样 ，但也大同小异。

具体的步骤如下：
转到内核目录：
//加载配置文件

>cp xxx .config
修改配置
make xxxx menuconfig
>-> Device Drivers -> USB support -> USB Gadget Support -> <M> USB Gadget Drivers -> <M> HID Gadget
进到：
>-> Device Drivers -> USB support > USB Gadget Support-> USB Peripheral Controller
> ->Device Drivers ->USB support > USB Gadget Support -> USB Peripheral Controller -> Hisilicon USB2. Device Controller SUPPORT
+ [*] Hisilicon USB2. Device auto switch

打开自动切换功能。
需要注意的是gadget子项的驱动依赖于udc模块和composite模块，而composite模块又依赖于udc模块，udc是硬件接口模块，直接操作USB寄存器等。composite为上层驱动提供操作UDC。

所以加载顺序必要是udc-hisi.ko 、libcomposite.ko 、g_hid.ko

加载发现出现问题，某些函数不能用，经过研究要打开

> File systems > Pseudo filesystems
+ {*} Userspace-driven configuration filesystem  

即可，加载g_hid.ko后出现：

insmod: can't insert 'g_hid.ko': No such device

原因在于没有注册设备报告描述符！！！修改hid.c文件， 头文件：

```
+#include <linux/usb/g_hid.h>
```

添加键盘报告描述符

+static struct hidg_func_descriptor keyboard_report_data =
+{
+    .subclass       = , /* No subclass */
+    .protocol       = , /* Keyboard */
+    .report_length      = ,
+    .report_desc_length = ,
+    .report_desc        = {
+    0x05, 0x01, /* USAGE_PAGE (Generic Desktop)           */
+        0x09, 0x06, /* USAGE (Keyboard)                       */
+        0xa1, 0x01, /* COLLECTION (Application)               */
+        0x05, 0x07, /*   USAGE_PAGE (Keyboard)                */
+        0x19, 0xe0, /*   USAGE_MINIMUM (Keyboard LeftControl) */
+        0x29, 0xe7, /*   USAGE_MAXIMUM (Keyboard Right GUI)   */
+        0x15, 0x00, /*   LOGICAL_MINIMUM (0)                  */
+        0x25, 0x01, /*   LOGICAL_MAXIMUM (1)                  */
+        0x75, 0x01, /*   REPORT_SIZE (1)                      */
+        0x95, 0x08, /*   REPORT_COUNT (8)                     */
+        0x81, 0x02, /*   INPUT (Data,Var,Abs)                 */
    +    0x95, 0x01, /*   REPORT_COUNT (1)                     */
    +    0x75, 0x08, /*   REPORT_SIZE (8)                      */
    +    0x81, 0x03, /*   INPUT (Cnst,Var,Abs)                 */
    +    0x95, 0x05, /*   REPORT_COUNT (5)                     */
    +    0x75, 0x01, /*   REPORT_SIZE (1)                      */
    +    0x05, 0x08, /*   USAGE_PAGE (LEDs)                    */
    +    0x19, 0x01, /*   USAGE_MINIMUM (Num Lock)             */
    +    0x29, 0x05, /*   USAGE_MAXIMUM (Kana)                 */
    +    0x91, 0x02, /*   OUTPUT (Data,Var,Abs)                */
    +    0x95, 0x01, /*   REPORT_COUNT (1)                     */
    +    0x75, 0x03, /*   REPORT_SIZE (3)                      */
    +    0x91, 0x03, /*   OUTPUT (Cnst,Var,Abs)                */
    +    0x95, 0x06, /*   REPORT_COUNT (6)                     */
    +    0x75, 0x08, /*   REPORT_SIZE (8)                      */
    +    0x15, 0x00, /*   LOGICAL_MINIMUM (0)                  */
    +    0x25, 0x65, /*   LOGICAL_MAXIMUM (101)                */
    +    0x05, 0x07, /*   USAGE_PAGE (Keyboard)                */
    +    0x19, 0x00, /*   USAGE_MINIMUM (Reserved)             */
    +    0x29, 0x65, /*   USAGE_MAXIMUM (Keyboard Application) */
    +    0x81, 0x00, /*   INPUT (Data,Ary,Abs)                 */
    +    0xc0        /* END_COLLECTION                         */
+};

定义键盘设备：

+static struct platform_device keyboard_device = {
+   .name           = "hidg",
+   .id         = ,
+   .num_resources      = ,
+   .resource       = ,
+   .dev.platform_data  = &keyboard_report_data,
+};  

在static int __init hidg_init(void)函数开始处注册键盘设备

+status = platform_device_register(&keyboard_device);
+    if (status < ) {
+        printk("____ reg failed\n");
+        platform_device_unregister(&keyboard_device);
+        return status;
+    } 

在驱动卸载处释放键盘设备

platform_driver_unregister(&hidg_plat_driver);
+platform_device_unregister(&keyboard_device);
usb_composite_unregister(&hidg_driver);

添加后即可识别为键盘设别如下图所示：

单个键盘和鼠标没有任何问题，然而同时设置鼠标和键盘加载后出现如下错误：

------------[ cut here ]------------
WARNING: CPU:  PID:  at fs/sysfs/dir.c: sysfs_warn_dup+0x60/0x70()
sysfs: cannot create duplicate filename ‘/devices/platform/hidg.’
Modules linked in: g_hid(+) libcomposite udc_hisi [last unloaded: g_hid]
CPU:  PID:  Comm: insmod Tainted: G W 3.18. #
[] (unwind_backtrace) from [] (show_stack+0x10/0x14)
[] (show_stack) from [] (dump_stack+0x88/0x98)
[] (dump_stack) from [] (warn_slowpath_common+0x6c/0x88)
[] (warn_slowpath_common) from [] (warn_slowpath_fmt+0x30/0x40)
[] (warn_slowpath_fmt) from [] (sysfs_warn_dup+0x60/0x70)
[] (sysfs_warn_dup) from [] (sysfs_create_dir_ns+0x88/0x98)
[] (sysfs_create_dir_ns) from [] (kobject_add_internal+0xb0/0x300)
[] (kobject_add_internal) from [] (kobject_add+0x48/0x94)
[] (kobject_add) from [] (device_add+0xd8/0x53c)
[] (device_add) from [] (platform_device_add+0xb4/0x21c)
[] (platform_device_add) from [] (hidg_init+0x38/0xc8 [g_hid])
[] (hidg_init [g_hid]) from [] (do_one_initcall+0x8c/0x1c8)
[] (do_one_initcall) from [] (load_module+0x1740/0x1e88)
[] (load_module) from [] (SyS_init_module+0xd8/0xec)
[] (SyS_init_module) from [] (ret_fast_syscall+0x0/0x38)
—[ end trace c7b2846a724052eb ]—

原因如下位置：

static struct platform_device mouse_device = {
.name = “hidg”,
.id = ,
.num_resources = ,
.resource = ,
.dev.platform_data = &mouse_report_desc,
};

id为0和keyboard的id也是0相同了冲突了！！ 经过这样子做，鼠标键盘在dev对应的是hidg0(键盘id 0) hidg1(鼠标id 1),只要打开这两个设备，往这两个设备发送键盘和鼠标报告就可以了

经过如此的配置只要按照顺序加载udc-hisi.ko、libcomposite.ko、以及g_hid.ko即可使用gadget鼠标键盘设备了，卸载这些驱动后，host又可以正常使用。