linux HID驱动分析
http://blog.csdn.net/walkingman321/article/details/7213710
HID 总线
HID的总线在hid-core.c的hid-init中初始化:
bus_register(&hid_bus_type);
hid_bus_type的定义:
static struct bus_type hid_bus_type = {
.name = "hid",*.match = hid_bus_match,*.probe = hid_device_probe,*.remove = hid_device_remove,*.uevent = hid_uevent,*
};
一般来说,HID驱动很少定义自己的probe函数,所以HID设备的匹配基本都是由总线probe和match函数完成。
HID的匹配
hid_bus_match用于检查设备和驱动的VID、PID是否匹配,代码如下:
*static int hid_bus_match(struct device *dev, struct device_driver drv)
struct hid_driver *hdrv = container_of(drv, struct hid_driver, driver);*struct hid_device *hdev = container_of(dev, struct hid_device, dev);*// 匹配hdev和hdrv的vendorID和productID*
if (!hid_match_device(hdev, hdrv))
return 0;*// 如果是generic-开头的驱动,那么只要不在黑名单中即可匹配*if (!strncmp(hdrv->name, "generic-", 8))*return !hid_match_id(hdev, hid_blacklist);*return 1;*
匹配了PID、VID之后,就进入到hid_device_probe函数:
*static int hid_device_probe(struct device dev)
struct hid_driver *hdrv = container_of(dev->driver, struct hid_driver, driver);*struct hid_device *hdev = container_of(dev, struct hid_device, dev);*const struct hid_device_id *id;*int ret = 0;*if (!hdev->driver) {*// 再匹配一次,这里似乎与前面的hid_bus_match有些重复*
id = hid_match_device(hdev, hdrv);
if (id == NULL)*return -ENODEV;*hdev->driver = hdrv;*if (hdrv->probe) { // 若驱动定义了自己的probe函数则调用该probe,但一般HID驱动不会定义*ret = hdrv->probe(hdev, id);*} else { // 默认的probe过程*ret = hid_parse(hdev);*if (!ret)*ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);*}*if (ret)*hdev->driver = NULL;*}*return ret;*
hid_parse函数的作用是解析HID描述符,具体实现由hid_device->ll_driver->parse函数完成。关于HID描述符的文档可在www.usb.org下载。
*static inline int __must_check hid_parse(struct hid_device hdev)
ret = hdev->ll_driver->parse(hdev);*
由于HID描述符的解析是通用操作,所以HID框架中实现了一个解析函数hid_parse_report。一般来说,hdev->ll_driver->parse函数中只要调用hid_parse_report即可。
hid_parse_report比较复杂,其功能是解析HID描述符,然后把解析出的结果放在hid_device->report_enum[type]-> report_list中。每个解析出的HID结构由一个hid_report描述。report_enum中的type可以是HID_INPUT_REPORT、HID_OUTPUT_REPORT或者HID_FEATURE_REPORT。
parse之后,probe函数又会调用hid_hw_start启动HID设备:
hid_hw_start(hdev, HID_CONNECT_DEFAULT);*
注意这里的HID_CONNECT_DEFAULT被定义为:
*#define HID_CONNECT_DEFAULT (HID_CONNECT_HIDINPUT|HID_CONNECT_HIDRAW| *
HID_CONNECT_HIDDEV|HID_CONNECT_FF)*
在hid_hw_start中,首先会调用hdev->ll_driver->start启动设备,然后是hid_connect将设备与HID框架关联起来。
hdev->ll_driver->start函数由hid的具体设备提供,由该设备所属的总线提供,用于底层的初始化,这里暂不讨论。
hid_connect会将hid_dev与具体驱动关联起来。
*int hid_connect(struct hid_device hdev, unsigned int connect_mask)
if (hdev->quirks & HID_QUIRK_HIDDEV_FORCE) // 一般不会到这里*connect_mask |= (HID_CONNECT_HIDDEV_FORCE | HID_CONNECT_HIDDEV);*if (hdev->bus != BUS_USB) // 如果不是USB总线,那么去掉HID_CONNECT_HIDDEV标记*connect_mask &= ~HID_CONNECT_HIDDEV;*if (hid_hiddev(hdev)) // 匹配某些特定vendorID和productID*connect_mask |= HID_CONNECT_HIDDEV_FORCE;*if ((connect_mask & HID_CONNECT_HIDINPUT) && !hidinput_connect(hdev,*connect_mask & HID_CONNECT_HIDINPUT_FORCE))*hdev->claimed |= HID_CLAIMED_INPUT;*if ((connect_mask & HID_CONNECT_HIDDEV) && hdev->hiddev_connect &&*!hdev->hiddev_connect(hdev,*connect_mask & HID_CONNECT_HIDDEV_FORCE))*hdev->claimed |= HID_CLAIMED_HIDDEV;*if ((connect_mask & HID_CONNECT_HIDRAW) && !hidraw_connect(hdev))*hdev->claimed |= HID_CLAIMED_HIDRAW;*
由此可见,hid_connect共支持3种设备,首先是input设备,调用hidinput_connect登记;其次是hid_dev设备,调用hdev->hiddev_connect登记;最后是raw设备,调用hidraw_connect登记。
HID input
HID中最常用的是input设备,使用hidinput_connect登记到系统。hidinput_connect的主要作用是对hiddev中的每一个report,都建立一个input_dev设备,并登记到input框架中。
*int hidinput_connect(struct hid_device hid, unsigned int force)
// 对每一个report,建立一个input设备*
for (k = HID_INPUT_REPORT; k <= max_report_type; k++)
list_for_each_entry(report, &hid->report_enum[k].report_list, list) {*if (!hidinput) {*hidinput = kzalloc(sizeof(*hidinput), GFP_KERNEL);*input_dev = input_allocate_device();*。。。*input_set_drvdata(input_dev, hid);*input_dev->event = hid->ll_driver->hidinput_input_event;*input_dev->open = hidinput_open;*input_dev->close = hidinput_close;*input_dev->setkeycode = hidinput_setkeycode;*input_dev->getkeycode = hidinput_getkeycode;*input_dev->name = hid->name;*input_dev->phys = hid->phys;*input_dev->uniq = hid->uniq;*input_dev->id.bustype = hid->bus;*input_dev->id.vendor = hid->vendor;*input_dev->id.product = hid->product;*input_dev->id.version = hid->version;*input_dev->dev.parent = hid->dev.parent;*hidinput->input = input_dev;*list_add_tail(&hidinput->list, &hid->inputs);*}*for (i = 0; i < report->maxfield; i++)*for (j = 0; j < report->field[i]->maxusage; j++)*hidinput_configure_usage(hidinput, report->field[i],*report->field[i]->usage + j);*}*
HID dev
HID dev设备目前仅在USB总线中用到,其用于登记的hiddev_connect函数指针目前仅有一个实例hiddev_connect,在usbhid_probe函数中被赋值。
hid->hiddev_connect = hiddev_connect;
HID raw dev
hidraw.c中定义了一个class hidraw,并创建设备设备驱动
alloc_chrdev_region(&dev_id, HIDRAW_FIRST_MINOR, HIDRAW_MAX_DEVICES, "hidraw");
cdev_init(&hidraw_cdev, &hidraw_ops);
hidraw_ops中定义了一个基本的字符设备驱动
static const struct file_operations hidraw_ops = {
.owner = THIS_MODULE,*.read = hidraw_read,*.write = hidraw_write,*.poll = hidraw_poll,*.open = hidraw_open,*.release = hidraw_release,*.unlocked_ioctl = hidraw_ioctl,*
};
由于是raw设备,所以这个驱动中不会解析任何数据,只是简单的将应用层数据传给下层设备,以及将设备产生的数据传给应用层。具体实现可查看代码。
hid-core.c
http://www.cs.fsu.edu/~baker/devices/lxr/http/source/linux/drivers/hid/hid-core.c#L495
hid-sersor-gyro-3d.c
http://lxr.free-electrons.com/source/drivers/iio/gyro/hid-sensor-gyro-3d.c#L264
android 驱动学习
http://blog.csdn.net/vv0_0vv/article/category/1067351











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