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标题: usb_register_dev 沒有在/dev底下新增裝置節點 [打印本页]

作者: rockwalking 时间: 2015-1-12 09:58
标题: usb_register_dev 沒有在/dev底下新增裝置節點
Dear Firefly:
      I encountered a problem for USB drivers that usb_register_dev do not create device under /dev
Here is the code

static char *flv_devnode(struct device *dev, umode_t *mode)
{
      return kasprintf(GFP_KERNEL, "%s", dev_name(dev));
}

static struct usb_class_driver flv_class_driver = {
      .name =          "flv%d",
      .fops =          &flv_fops_nop,
      .devnode = flv_devnode,
      .minor_base = FLV_MINOR_BASE,
};

Static int flv_probe(struct usb_interface dev_if, …)
{

      usb_set_intfdata(dev_if, &flv_class_driver);

      retval = usb_register_dev(dev_if, &flv_class_driver);
      if (retval != 0) {
            /* something prevented us from registering this driver */
            printk(KERN_INFO "%s() unable to get a minor for this device.\n", __func__);
            usb_set_intfdata(dev_if, NULL);
            goto _safe_exit;
      }
}

The function usb_register_dev should create file not only under /sys/class/usbmisc/flv0, but under /dev/flv0.
However, I cannot see the device file under /dev.

I also refer to snd_register_device(), which successfully create device under /dev/snd, but can not find the key place.

Could you give me some suggestions?  Thank you very much.

Thanks,

作者: rockwalking 时间: 2015-1-13 14:48
Android init process will ignore usb uevent, so please modified  ~/$proj/system/core/init/device.c

...
if (!strncmp(uevent->subsystem, "usb", 3)) {
      if (!strcmp(uevent->subsystem, "usb")) {
         if (uevent->device_name) {
            /*
               * create device node provided by kernel if present
               * see drivers/base/core.c
               */
            char *p = devpath;
            snprintf(devpath, sizeof(devpath), "/dev/%s", uevent->device_name);
            /* skip leading /dev/ */
            p += 5;
            /* build directories */
            while (*p) {
                  if (*p == '/') {
                     *p = 0;
                     make_dir(devpath, 0755);
                     *p = '/';
                  }
                  p++;
            }
         }
         else {
               /* This imitates the file system that would be created
               * if we were using devfs instead.
               * Minors are broken up into groups of 128, starting at "001"
               */
               int bus_id = uevent->minor / 128 + 1;
               int device_id = uevent->minor % 128 + 1;
               /* build directories */
               make_dir("/dev/bus", 0755);
               make_dir("/dev/bus/usb", 0755);
               snprintf(devpath, sizeof(devpath), "/dev/bus/usb/%03d", bus_id);
               make_dir(devpath, 0755);
               snprintf(devpath, sizeof(devpath), "/dev/bus/usb/%03d/%03d", bus_id, device_id);
         }
      } else {
         /* ignore other USB events */
   if(!strncmp(name, "flv",3)){
   base = "/dev/";
   }
   else
return;
      }
...

作者: zhansb 时间: 2015-1-13 19:08
{:3_48:}nice

作者: huoooooo 时间: 2017-1-18 11:05

thx.

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