1. 指定USB鍵盤驅動所需的頭文件:
#include<linux/kernel.h>/*內核頭文件,含有內核一些常用函數的原型定義*/
#include<linux/slab.h>/*定義內存分配的一些函數*/
#include<linux/module.h>/*模塊編譯必須的頭文件*/
#include<linux/input.h>/*輸入設備相關函數的頭文件*/
#include<linux/init.h>/*linux初始化模塊函數定義*/
#include<linux/usb.h> /*USB設備相關函數定義*/
2. 定義鍵盤碼錶數組:
/*使用第一套鍵盤掃描碼錶:A-1E;B-30;C-2E…*/
static unsigned char usb_kbd_keycode[256] = {
0, 0, 0, 0, 30, 48, 46, 32, 18, 33, 34, 35, 23, 36, 37, 38,
50, 49, 24, 25, 16, 19, 31, 20, 22, 47, 17, 45, 21, 44, 2, 3,
4, 5, 6, 7, 8, 9, 10, 11, 28, 1, 14, 15, 57, 12, 13, 26,
27, 43, 43, 39, 40, 41, 51, 52, 53, 58, 59, 60, 61, 62, 63, 64,
65, 66, 67, 68, 87, 88, 99, 70,119,110,102,104,111,107,109,106,
105,108,103, 69, 98, 55, 74, 78, 96, 79, 80, 81, 75, 76, 77, 71,
72, 73, 82, 83, 86,127,116,117,183,184,185,186,187,188,189,190,
191,192,193,194,134,138,130,132,128,129,131,137,133,135,136,113,
115,114, 0, 0, 0,121, 0, 89, 93,124, 92, 94, 95, 0, 0, 0,
122,123, 90, 91, 85, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
29, 42, 56,125, 97, 54,100,126,164,166,165,163,161,115,114,113,
150,158,159,128,136,177,178,176,142,152,173,140
};
3. 編寫設備ID表:
static struct usb_device_id usb_kbd_id_table [] = {
{ USB_INTERFACE_INFO(3, 1, 1) },/*3,1,1分別表示接口類,接口子類,接口協議;3,1,1爲鍵盤接口類;鼠標爲3,1,2*/
{ } /* Terminating entry */
};
MODULE_DEVICE_TABLE (usb, usb_kbd_id_table);/*指定設備ID表*/
4. 定義USB鍵盤結構體:
struct usb_kbd {
struct input_dev *dev; /*定義一個輸入設備*/
struct usb_device *usbdev;/*定義一個usb設備*/
unsigned char old[8]; /*按鍵離開時所用之數據緩衝區*/
struct urb *irq/*usb鍵盤之中斷請求塊*/, *led/*usb鍵盤之指示燈請求塊*/;
unsigned char newleds;/*目標指定燈狀態*/
char name[128];/*存放廠商名字及產品名字*/
char phys[64];/*設備之節點*/
unsigned char *new;/*
按鍵按下時所用之數據緩衝區*/
struct usb_ctrlrequest *cr;/*控制請求結構*/
unsigned char *leds;/*當前指示燈狀態*/
dma_addr_t cr_dma; /*控制請求DMA緩衝地址*/
dma_addr_t new_dma; /*中斷urb會使用該DMA緩衝區*/
dma_addr_t leds_dma; /*指示燈DAM緩衝地址*/
};
5. 編寫USB鍵盤驅動結構(任何一個LINUX下的驅動都有個類似的驅動結構):
/*USB鍵盤驅動結構體*/
static struct usb_driver usb_kbd_driver = {
.name = "usbkbd",/*驅動名字*/
.probe = usb_kbd_probe,/*驅動探測函數,加載時用到*/
.disconnect = usb_kbd_disconnect,/*驅動斷開函數,在卸載時用到*/
.id_table = usb_kbd_id_table,/*驅動設備ID表,用來指定設備或接口*/
};
6. 編寫模塊加載函數(每個驅動都會有一個加載函數,由module_init調用):
/*驅動程序生命週期的開始點,向 USB core 註冊這個鍵盤驅動程序。*/
static int __init usb_kbd_init(void)
{
int result = usb_register(&usb_kbd_driver);/*註冊USB鍵盤驅動*/
if (result == 0) /*註冊失敗*/
info(DRIVER_VERSION ":" DRIVER_DESC);
return result;
}
7. 編寫模塊卸載函數(每個驅動都會有一個卸載函數,由module_exit調用):
/*驅動程序生命週期的結束點,向 USB core 註銷這個鍵盤驅動程序。 */
static void __exit usb_kbd_exit(void)
{
printk("SUNWILL-USBKBD:usb_kbd_exit begin.../n");
usb_deregister(&usb_kbd_driver);/*註銷USB鍵盤驅動*/
}
8. 指定模塊初始化函數(被指定的函數在insmod驅動時調用):
module_init(usb_kbd_init);
9. 指定模塊退出函數(被指定的函數在rmmod驅動時調用):
module_exit(usb_kbd_exit);
10. 編寫中斷請求處理函數:
/*中斷請求處理函數,有中斷請求到達時調用該函數*/
static void usb_kbd_irq(struct urb *urb, struct pt_regs *regs)
{
struct usb_kbd *kbd = urb->context;
int i;
switch (urb->status) {
case 0: /* success */
break;
case -ECONNRESET: /* unlink */
case -ENOENT:
case -ESHUTDOWN:
return;
/* -EPIPE: should clear the halt */
default: /* error */
goto resubmit;
}
//input_regs(kbd->dev, regs);
/*
不知道其用意, 註釋掉該部分仍可正常工作*/
for (i = 0; i < 8; i++)/*8次的值依次是:29-42-56-125-97-54-100-126*/
{
input_report_key(kbd->dev, usb_kbd_keycode[i + 224], (kbd->new[0] >> i) & 1);
}
/*若同時只按下1個按鍵則在第[2]個字節,若同時有兩個按鍵則第二個在第[3]字節,類推最多可有6個按鍵同時按下*/
for (i = 2; i < 8; i++) {
/*獲取鍵盤離開的中斷*/
if (kbd->old > 3 && memscan(kbd->new + 2, kbd->old, 6) == kbd->new + 8) {/*同時沒有該KEY的按下狀態*/
if (usb_kbd_keycode[kbd->old])
{
input_report_key(kbd->dev, usb_kbd_keycode[kbd->old], 0);
}
else
info("Unknown key (scancode %#x) released.", kbd->old);
}
/*
獲取鍵盤按下的中斷*/
if (kbd->new > 3 && memscan(kbd->old + 2, kbd->new, 6) == kbd->old + 8) {/*同時沒有該KEY的離開狀態*/
if (usb_kbd_keycode[kbd->new])
{
input_report_key(kbd->dev, usb_kbd_keycode[kbd->new], 1);
}
else
info("Unknown key (scancode %#x) pressed.", kbd->new);
}
}
/*同步設備,告知事件的接收者驅動已經發出了一個完整的報告*/
input_sync(kbd->dev);
memcpy(kbd->old, kbd->new, 8);/*防止未鬆開時被當成新的按鍵處理*/
resubmit:
i = usb_submit_urb (urb, GFP_ATOMIC);/*發送USB請求塊*/
if (i)
err ("can't resubmit intr, %s-%s/input0, status %d",
kbd->usbdev->bus->bus_name,
kbd->usbdev->devpath, i);
}
11. 編寫事件處理函數:
/*事件處理函數*/
static int usb_kbd_event(struct input_dev *dev, unsigned int type,
unsigned int code, int value)
{
struct usb_kbd *kbd = dev->private;
if (type != EV_LED) /*不支持LED事件 */
return -1;
/*獲取指示燈的目標狀態*/
kbd->newleds = (!!test_bit(LED_KANA, dev->led) << 3) | (!!test_bit(LED_COMPOSE, dev->led) << 3) |
(!!test_bit(LED_SCROLLL, dev->led) << 2) | (!!test_bit(LED_CAPSL, dev->led) << 1) |
(!!test_bit(LED_NUML, dev->led));
if (kbd->led->status == -EINPROGRESS)
return 0;
/*
指示燈狀態已經是目標狀態則不需要再做任何操作*/
if (*(kbd->leds) == kbd->newleds)
return 0;
*(kbd->leds) = kbd->newleds;
kbd->led->dev = kbd->usbdev;
/*發送usb請求塊*/
if (usb_submit_urb(kbd->led, GFP_ATOMIC))
err("usb_submit_urb(leds) failed");
return 0;
}
12. 編寫LED事件處理函數:
/*接在event之後操作,該功能其實usb_kbd_event中已經有了,該函數的作用可能是防止event的操作失敗,一般註釋掉該函數中的所有行都可以正常工作*/
static void usb_kbd_led(struct urb *urb, struct pt_regs *regs)
{
struct usb_kbd *kbd = urb->context;
if (urb->status)
warn("led urb status %d received", urb->status);
if (*(kbd->leds) == kbd->newleds)/*
指示燈狀態已經是目標狀態則不需要再做任何操作*/
return;
*(kbd->leds) = kbd->newleds;
kbd->led->dev = kbd->usbdev;
if (usb_submit_urb(kbd->led, GFP_ATOMIC))
err("usb_submit_urb(leds) failed");
}
13. 編寫USB設備打開函數:
/*打開鍵盤設備時,開始提交在 probe 函數中構建的 urb,進入 urb 週期。 */
static int usb_kbd_open(struct input_dev *dev)
{
struct usb_kbd *kbd = dev->private;
kbd->irq->dev = kbd->usbdev;
if (usb_submit_urb(kbd->irq, GFP_KERNEL))
return -EIO;
return 0;
}
14. 編寫USB設備關閉函數
/*關閉鍵盤設備時,結束 urb 生命週期。 */
static void usb_kbd_close(struct input_dev *dev)
{
struct usb_kbd *kbd = dev->private;
usb_kill_urb(kbd->irq); /*取消kbd->irq這個usb請求塊*/
}
15. 創建URB
/*分配URB內存空間即創建URB*/
static int usb_kbd_alloc_mem(struct usb_device *dev, struct usb_kbd *kbd)
{
if (!(kbd->irq = usb_alloc_urb(0, GFP_KERNEL)))
return -1;
if (!(kbd->led = usb_alloc_urb(0, GFP_KERNEL)))
return -1;
if (!(kbd->new = usb_buffer_alloc(dev, 8, GFP_ATOMIC, &kbd->new_dma)))
return -1;
if (!(kbd->cr = usb_buffer_alloc(dev, sizeof(struct usb_ctrlrequest), GFP_ATOMIC, &kbd->cr_dma)))
return -1;
if (!(kbd->leds = usb_buffer_alloc(dev, 1, GFP_ATOMIC, &kbd->leds_dma)))
return -1;
return 0;
}
16. 銷燬URB
/*釋放URB內存空間即銷燬URB*/
static void usb_kbd_free_mem(struct usb_device *dev, struct usb_kbd *kbd)
{
if (kbd->irq)
usb_free_urb(kbd->irq);
if (kbd->led)
usb_free_urb(kbd->led);
if (kbd->new)
usb_buffer_free(dev, 8, kbd->new, kbd->new_dma);
if (kbd->cr)
usb_buffer_free(dev, sizeof(struct usb_ctrlrequest), kbd->cr, kbd->cr_dma);
if (kbd->leds)
usb_buffer_free(dev, 1, kbd->leds, kbd->leds_dma);
}
17. USB鍵盤驅動探測函數:
/*USB鍵盤驅動探測函數,初始化設備並指定一些處理函數的地址*/
static int usb_kbd_probe(struct usb_interface *iface,
const struct usb_device_id *id)
{
struct usb_device *dev = interface_to_usbdev(iface);
struct usb_host_interface *interface;
struct usb_endpoint_descriptor *endpoint;
struct usb_kbd *kbd;
struct input_dev *input_dev;
int i, pipe, maxp;
/*當前選擇的interface*/
interface = iface->cur_altsetting;
/*鍵盤只有一箇中斷IN端點*/
if (interface->desc.bNumEndpoints != 1)
return -ENODEV;
/*獲取端點描述符*/
endpoint = &interface->endpoint[0].desc;
if (!(endpoint->bEndpointAddress & USB_DIR_IN))
return -ENODEV;
if ((endpoint->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) != USB_ENDPOINT_XFER_INT)
return -ENODEV;
/*將endpoint設置爲中斷IN端點*/
pipe = usb_rcvintpipe(dev, endpoint->bEndpointAddress);
/*獲取包的最大值*/
maxp = usb_maxpacket(dev, pipe, usb_pipeout(pipe));
kbd = kzalloc(sizeof(struct usb_kbd), GFP_KERNEL);
input_dev = input_allocate_device();
if (!kbd || !input_dev)
goto fail1;
if (usb_kbd_alloc_mem(dev, kbd))
goto fail2;
/*填充 usb 設備結構體和輸入設備結構體 */
kbd->usbdev = dev;
kbd->dev = input_dev;
/*
以"廠商名字 產品名字"的格式將其寫入kbd->name*/
if (dev->manufacturer)
strlcpy(kbd->name, dev->manufacturer, sizeof(kbd->name));
if (dev->product) {
if (dev->manufacturer)
strlcat(kbd->name, " ", sizeof(kbd->name));
strlcat(kbd->name, dev->product, sizeof(kbd->name));
}
/*
檢測不到廠商名字*/
if (!strlen(kbd->name))
snprintf(kbd->name, sizeof(kbd->name),
"USB HIDBP Keyboard %04x:%04x",
le16_to_cpu(dev->descriptor.idVendor),
le16_to_cpu(dev->descriptor.idProduct));
/*設備鏈接地址*/
usb_make_path(dev, kbd->phys, sizeof(kbd->phys));
strlcpy(kbd->phys, "/input0", sizeof(kbd->phys));
input_dev->name = kbd->name;
input_dev->phys = kbd->phys;
/*
* input_dev中的 input_id 結構體,用來存儲廠商、設備類型和設備的編號,這個函數是將設備描述符
*中的編號賦給內嵌的輸入子系統結構體
*/
usb_to_input_id(dev, &input_dev->id);
/* cdev是設備所屬類別(class device) */
input_dev->cdev.dev = &iface->dev;
/* input_dev的 private 數據項用於表示當前輸入設備的種類,這裏將鍵盤結構體對象賦給它 */
input_dev->private = kbd;
input_dev->evbit[0] = BIT(EV_KEY)/*鍵碼事件*/ | BIT(EV_LED)/*LED事件*/ | BIT(EV_REP)/*自動重覆數值*/;
input_dev->ledbit[0] = BIT(LED_NUML)/*數字燈*/ | BIT(LED_CAPSL)/*大小寫燈*/ | BIT(LED_SCROLLL)/*滾動燈*/ | BIT(LED_COMPOSE) | BIT(LED_KANA);
for (i = 0; i < 255; i++)
set_bit(usb_kbd_keycode, input_dev->keybit);
clear_bit(0, input_dev->keybit);
input_dev->event = usb_kbd_event;/*
註冊事件處理函數入口*/
input_dev->open = usb_kbd_open;/*註冊設備打開函數入口*/
input_dev->close = usb_kbd_close;/*註冊設備關閉函數入口*/
/*
初始化中斷URB*/
usb_fill_int_urb(kbd->irq/*初始化kbd->irq這個urb*/, dev/*這個urb要發送到dev這個設備*/, pipe/*這個urb要發送到pipe這個端點*/,
kbd->new/*指向緩衝的指針*/, (maxp > 8 ? 8 : maxp)/*緩衝長度*/,
usb_kbd_irq/*這個urb完成時調用的處理函數*/, kbd/*指向數據塊的指針,被添加到這個urb結構可被完成處理函數獲取*/, endpoint->bInterval/*urb應當被調度的間隔*/);
kbd->irq->transfer_dma = kbd->new_dma; /*指定urb需要傳輸的DMA緩衝區*/
kbd->irq->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;/*本urb有一個DMA緩衝區需要傳輸*/
kbd->cr->bRequestType = USB_TYPE_CLASS | USB_RECIP_INTERFACE;/*操作的是類接口對象*/
kbd->cr->bRequest = 0x09; /*中斷請求編號*/
kbd->cr->wValue = cpu_to_le16(0x200);
kbd->cr->wIndex = cpu_to_le16(interface->desc.bInterfaceNumber);/*接口號*/
kbd->cr->wLength = cpu_to_le16(1);/*數據傳輸階段傳輸多少個bytes*/
/*
初始化控制URB*/
usb_fill_control_urb(kbd->led, dev, usb_sndctrlpipe(dev, 0),
(void *) kbd->cr, kbd->leds, 1,
usb_kbd_led, kbd);
kbd->led->setup_dma = kbd->cr_dma;
kbd->led->transfer_dma = kbd->leds_dma;
kbd->led->transfer_flags |= (URB_NO_TRANSFER_DMA_MAP | URB_NO_SETUP_DMA_MAP/*如果使用DMA傳輸則urb中setup_dma指針所指向的緩衝區是DMA緩衝區而不是setup_packet所指向的緩衝區*/);
/*
註冊輸入設備*/
input_register_device(kbd->dev);
usb_set_intfdata(iface, kbd);/*設置接口私有數據*/
return 0;
fail2: usb_kbd_free_mem(dev, kbd);
fail1: input_free_device(input_dev);
kfree(kbd);
return -ENOMEM;
}
18. 編寫斷開連接的函數:
/*斷開連接(如鍵盤設備拔出)的處理函數*/
static void usb_kbd_disconnect(struct usb_interface *intf)
{
struct usb_kbd *kbd = usb_get_intfdata (intf);/*獲取接口的私有數據給kbd*/
usb_set_intfdata(intf, NULL);/*設置接口的私有數據爲NULL*/
if (kbd) {
usb_kill_urb(kbd->irq);/*取消中斷請求*/
input_unregister_device(kbd->dev);/*註銷設備*/
usb_kbd_free_mem(interface_to_usbdev(intf), kbd);/*釋放內存空間*/
kfree(kbd);
}
}
19. 編寫Makefile:
##############################
#usbkdb Makefile for linux
##############################
obj-m:=usbkbd.o
KERNELDIR ?= /lib/modules/$(shell uname -r)/build
PWD:=$(shell pwd)
default:
$(MAKE) -C $(KERNELDIR) M=$(PWD) modules