USB拓扑结构
USB通信模型
USB事件流程
USB设备枚举
hub守护线程hub_thread()监控hub端口状态，一旦有外设连接，经过加电、缺省、编址、配置、挂起等一些列状态配置后，设备处于挂起状态，等待中断输入。
USB数据传输类型
USB设备类型描述
USB是一种电缆总线，支持在主机和各式各样的即插即用的外设之间进行数据传输。由主机预定的标准的协议使各种设备分享USB带宽，当其它设备和主机在运行时，总线允许添加、设置、使用以及拆除外设。
一个USB系统主要被定义为三个部分：
·USB的互连；
·USB的设备；
·USB的主机。
USB的互连是指USB设备与主机之间进行连接和通信的操作，主要包括以下几方面：
·总线的拓扑结构：USB设备与主机之间的各种连接方式；
·内部层次关系：根据性能叠置，USB的任务被分配到系统的每一个层次；
·数据流模式：描述了数据在系统中通过USB从产生方到使用方的流动方式；
·USB的调度：USB提供了一个共享的连接。对可以使用的连接进行了调度以支持同步数据传输，并且避免的优先级判别的开销。
在任何USB系统中，只有一个主机。USB和主机系统的接口称作主机控制器，主机控制器可由硬件、固件和软件综合实现。根集线器是由主机系统整合的，用以提供更多的连接点
主机控制器的驱动程序(HCD)：它位于USB主机控制器与USB系统软件之间。主机控制器可以有一系列不同的实现，而系统软件独立于任何一个具体实现。一个驱动程序可以支持不同的控制器，而不必特别了解这个具体的控制器。一个USB控制器的实现者必须提供一个支持它自己的控制器的主机控制器驱动器（HCD）实现。
USB驱动程序(USBD)：USB系统软件与客户软件之间的接口，提供给客户软件一些方便的使用USB设备的功能。
相关数据结构：
struct input_dev {
void *private; //struct usb_kbd
const char *name; //usb_kbd->name
const char *phys; //usb_kbd->phys
const char *uniq;
struct input_id id;
unsigned long evbit[NBITS(EV_MAX)]; //event bit，产生或接受什么样的事件的指示位
unsigned long keybit[NBITS(KEY_MAX)]; //产生或接受什么样的按键代码
unsigned long relbit[NBITS(REL_MAX)]; //相对定位
unsigned long absbit[NBITS(ABS_MAX)]; //绝对定位
unsigned long mscbit[NBITS(MSC_MAX)]; /*Mouse Systems Corporation，参见[url][/url]，大意是一些厂商使用了5字节的串口鼠标协议，但微软使用了一种三字节协议，于是厂商造串口鼠标时，让设备有两种工作模式，一种是MSC模式，一种是微软的模式*/
unsigned long ledbit[NBITS(LED_MAX)]; //键盘指示灯事件的指示位
unsigned long sndbit[NBITS(SND_MAX)]; //键盘发出声音的指示位
unsigned long ffbit[NBITS(FF_MAX)]; //force feedback，强制反馈设备
unsigned long swbit[NBITS(SW_MAX)]; //switch，设备切换时产生的事件
int ff_effects_max;
unsigned int keycodemax;
unsigned int keycodesize;
void *keycode;
unsigned int repeat_key;
struct timer_list timer;
struct pt_regs *regs;
int state;
int sync;
int abs[ABS_MAX + 1];
int rep[REP_MAX + 1];
unsigned long key[NBITS(KEY_MAX)];
unsigned long led[NBITS(LED_MAX)];
unsigned long snd[NBITS(SND_MAX)];
unsigned long sw[NBITS(SW_MAX)];
int absmax[ABS_MAX + 1];
int absmin[ABS_MAX + 1];
int absfuzz[ABS_MAX + 1];
int absflat[ABS_MAX + 1];
int (*open)(struct input_dev *dev);
void (*close)(struct input_dev *dev);
int (*accept)(struct input_dev *dev, struct file *file);
int (*flush)(struct input_dev *dev, struct file *file);
int (*event)(struct input_dev *dev, unsigned int type, unsigned int code, int value);
int (*upload_effect)(struct input_dev *dev, struct ff_effect *effect);
int (*erase_effect)(struct input_dev *dev, int effect_id);
struct input_handle *grab;
struct semaphore sem; /* serializes open and close operations */
unsigned int users;
struct device *dev;
struct list_head h_list;
struct list_head node;
};
usbkbd.c代码分析
/*
* $Id: usbkbd.c,v 1.27 2001/12/27 10:37:41 vojtech Exp $
*
* Copyright (c) 1999-2001 Vojtech Pavlik
*
* USB HIDBP Keyboard support
*/
/*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* Should you need to contact me, the author, you can do so either by
* e-mail - mail your message to <>, or by paper mail:
* Vojtech Pavlik, Simunkova 1594, Prague 8, 182 00 Czech Republic
*/
#include
#include
#include
#include
#include
#include
#include
/*
* Version Information
*/
#define DRIVER_VERSION ""
#define DRIVER_AUTHOR "Vojtech Pavlik <>"
#define DRIVER_DESC "USB HID Boot Protocol keyboard driver"
#define DRIVER_LICENSE "GPL"
MODULE_AUTHOR(DRIVER_AUTHOR);
MODULE_DESCRIPTION(DRIVER_DESC);
MODULE_LICENSE(DRIVER_LICENSE);
//键盘键值映射表
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
};
//usb键盘结构体
struct usb_kbd {
struct input_dev dev; //输入设备结构体
struct usb_device *usbdev; //USB设备
unsigned char old[8];
struct urb *irq, *led; //
unsigned char newleds;
//制造商，产品名等描述
//例： kbd->name:CHESEN USB Keyboard,kbd->phys:usb-s3c24xx-1/input0
char name[128];
//路径
// kbd->phys:usb-s3c24xx-1/input0 (usb-%usb_device->bus->bus_name%-%usb_device->devpath%/input0)
char phys[64];
unsigned char *new;
struct usb_ctrlrequest *cr;
unsigned char *leds;
dma_addr_t cr_dma;
dma_addr_t new_dma;
dma_addr_t leds_dma;
};
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);
/*报告usb_kbd_keycode[224..231]8按键状态（KEY_LEFTCTRL,KEY_LEFTSHIFT,KEY_LEFTALT,KEY_LEFTMETA
,KEY_RIGHTCTRL,KEY_RIGHTSHIFT,KEY_RIGHTALT,KEY_RIGHTMETA）
*/
for (i = 0; i < 8; i++)
input_report_key(&kbd->dev, usb_kbd_keycode[i + 224], (kbd->new[0] >> i) & 1);
for (i = 2; i < 8; i++) {
if (kbd->old[i] > 3 && memscan(kbd->new + 2, kbd->old[i], 6) == kbd->new + 8) {
if (usb_kbd_keycode[kbd->old[i]])
input_report_key(&kbd->dev, usb_kbd_keycode[kbd->old[i]], 0);
else
info("Unknown key (scancode %#x) released.", kbd->old[i]);
}
if (kbd->new[i] > 3 && memscan(kbd->old + 2, kbd->new[i], 6) == kbd->old + 8) {
if (usb_kbd_keycode[kbd->new[i]])
input_report_key(&kbd->dev, usb_kbd_keycode[kbd->new[i]], 1);
else
info("Unknown key (scancode %#x) pressed.", kbd->new[i]);
}
}
input_sync(&kbd->dev);
memcpy(kbd->old, kbd->new, 8);
resubmit:
i = usb_submit_urb (urb, SLAB_ATOMIC);
if (i)
err ("can't resubmit intr, %s-%s/input0, status %d",
kbd->usbdev->bus->bus_name,
kbd->usbdev->devpath, i);
}
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)
return -1;
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;
if (*(kbd->leds) == kbd->newleds)
return 0;
*(kbd->leds) = kbd->newleds;
kbd->led->dev = kbd->usbdev;
if (usb_submit_urb(kbd->led, GFP_ATOMIC))
err("usb_submit_urb(leds) failed");
return 0;
}
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)
return;
*(kbd->leds) = kbd->newleds;
kbd->led->dev = kbd->usbdev;
if (usb_submit_urb(kbd->led, GFP_ATOMIC))
err("usb_submit_urb(leds) failed");
}
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;
}
static void usb_kbd_close(struct input_dev *dev)
{
struct usb_kbd *kbd = dev->private;
usb_kill_urb(kbd->irq);
}
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, SLAB_ATOMIC, &kbd->new_dma)))
return -1;
if (!(kbd->cr = usb_buffer_alloc(dev, sizeof(struct usb_ctrlrequest), SLAB_ATOMIC, &kbd->cr_dma)))
return -1;
if (!(kbd->leds = usb_buffer_alloc(dev, 1, SLAB_ATOMIC, &kbd->leds_dma)))
return -1;
return 0;
}
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);
}
static int usb_kbd_probe(struct usb_interface *iface,
const struct usb_device_id *id)
{
struct usb_device * dev = interface_to_usbdev(iface); //通过接口获取USB设备指针
struct usb_host_interface *interface;
struct usb_endpoint_descriptor *endpoint;
struct usb_kbd *kbd;
int i, pipe, maxp;
char path[64];
interface = iface->cur_altsetting;
if (interface->desc.bNumEndpoints != 1)
return -ENODEV;
endpoint = &interface->endpoint[0].desc;
if (!(endpoint->bEndpointAddress & 0x80))
return -ENODEV;
if ((endpoint->bmAttributes & 3) != 3)
return -ENODEV;
pipe = usb_rcvintpipe(dev, endpoint->bEndpointAddress);
maxp = usb_maxpacket(dev, pipe, usb_pipeout(pipe));
if (!(kbd = kmalloc(sizeof(struct usb_kbd), GFP_KERNEL)))
return -ENOMEM;
memset(kbd, 0, sizeof(struct usb_kbd));
//分配 kbd相关变量内存
if (usb_kbd_alloc_mem(dev, kbd)) {
usb_kbd_free_mem(dev, kbd);
kfree(kbd);
return -ENOMEM;
}
kbd->usbdev = dev;
kbd->dev.evbit[0] = BIT(EV_KEY) | BIT(EV_LED) | BIT(EV_REP);
kbd->dev.ledbit[0] = BIT(LED_NUML) | BIT(LED_CAPSL) | BIT(LED_SCROLLL) | BIT(LED_COMPOSE) | BIT(LED_KANA);
for (i = 0; i < 255; i++)
set_bit(usb_kbd_keycode[i], kbd->dev.keybit);
clear_bit(0, kbd->dev.keybit);
kbd->dev.private = kbd;
kbd->dev.event = usb_kbd_event;
kbd->dev.open = usb_kbd_open;
kbd->dev.close = usb_kbd_close;
usb_fill_int_urb(kbd->irq, dev, pipe,
kbd->new, (maxp > 8 ? 8 : maxp),
usb_kbd_irq, kbd, endpoint->bInterval);
kbd->irq->transfer_dma = kbd->new_dma;
kbd->irq->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
kbd->cr->bRequestType = USB_TYPE_CLASS | USB_RECIP_INTERFACE;
kbd->cr->bRequest = 0x09;
kbd->cr->wValue = cpu_to_le16(0x200);
kbd->cr->wIndex = cpu_to_le16(interface->desc.bInterfaceNumber);
kbd->cr->wLength = cpu_to_le16(1);
usb_make_path(dev, path, 64);
sprintf(kbd->phys, "%s/input0", path);
kbd->dev.name = kbd->name;
kbd->dev.phys = kbd->phys;
usb_to_input_id(dev, &kbd->dev.id);
kbd->dev.dev = &iface->dev;
if (dev->manufacturer)
strcat(kbd->name, dev->manufacturer);
if (dev->product)
sprintf(kbd->name, "%s %s", kbd->name, dev->product);
if (!strlen(kbd->name))
sprintf(kbd->name, "USB HIDBP Keyboard %04x:%04x",
kbd->dev.id.vendor, kbd->dev.id.product);
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);
input_register_device(&kbd->dev);
printk(KERN_INFO "input: %s on %s\n", kbd->name, path);
usb_set_intfdata(iface, kbd);
return 0;
}
static void usb_kbd_disconnect(struct usb_interface *intf)
{
struct usb_kbd *kbd = usb_get_intfdata (intf);
usb_set_intfdata(intf, NULL);
if (kbd) {
usb_kill_urb(kbd->irq);
input_unregister_device(&kbd->dev);
usb_kbd_free_mem(interface_to_usbdev(intf), kbd);
kfree(kbd);
}
}
static struct usb_device_id usb_kbd_id_table [] = {
{ USB_INTERFACE_INFO(3, 1, 1) },
{ } /* Terminating entry */
};
MODULE_DEVICE_TABLE (usb, usb_kbd_id_table);
static struct usb_driver usb_kbd_driver = {
.owner = THIS_MODULE,
.name = "usbkbd",
.probe = usb_kbd_probe,
.disconnect = usb_kbd_disconnect,
.id_table = usb_kbd_id_table,
};
static int __init usb_kbd_init(void)
{
int result = usb_register(&usb_kbd_driver);
if (result == 0)
info(DRIVER_VERSION ":" DRIVER_DESC);
return result;
}
static void __exit usb_kbd_exit(void)
{
usb_deregister(&usb_kbd_driver);
}
module_init(usb_kbd_init);
module_exit(usb_kbd_exit);
