usb: sandbox: Fix emulator device select logic in usb_emul_find_devnum()

Current emulator select logic in usb_emul_find_devnum() is to test
the USB address. The USB address of the device being enumerated is
initialized to zero at the beginning of the enumeration process in
usb_setup_device(). At this point, the saved USB address in the
platform data has not been assigned to any valid USB address either.
This means: the logic will select an emulator device according to
its sequence of declaring order in the device tree. Take test.dts
for example, flash-stick@0 will be selected before flash-stick@1.
But unfortunately such logic is wrong.

In fact USB devices show up in a random order during the enumeration
which means usb_emul_find_devnum() may be called on port 3 for keyb@3
before on port 0 for flash-stick@0.

To fix this, we introduce a new emulator uclass specific platdata
to store the USB device's port number on its parent hub, and update
the logic to test the port number instead.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>

1 files changed, 16 insertions, 2 deletions

diff --git a/include/usb.h b/include/usb.h
index 3d517316e5b..63eddddc914 100644
--- a/include/usb.h
+++ b/include/usb.h
@@ -653,6 +653,18 @@ struct usb_bus_priv {
 };
 
 /**
+ * struct usb_emul_platdata - platform data about the USB emulator
+ *
+ * Given a USB emulator (UCLASS_USB_EMUL) 'dev', this is
+ * dev_get_uclass_platdata(dev).
+ *
+ * @port1:	USB emulator device port number on the parent hub
+ */
+struct usb_emul_platdata {
+	int port1;	/* Port number (numbered from 1) */
+};
+
+/**
  * struct dm_usb_ops - USB controller operations
  *
  * This defines the operations supoorted on a USB controller. Common
@@ -1023,14 +1035,16 @@ int usb_emul_int(struct udevice *emul, struct usb_device *udev,
 /**
  * usb_emul_find() - Find an emulator for a particular device
  *
- * Check @pipe to find a device number on bus @bus and return it.
+ * Check @pipe and @port1 to find a device number on bus @bus and return it.
  *
  * @bus:	USB bus (controller)
  * @pipe:	Describes pipe being used, and includes the device number
+ * @port1:	Describes port number on the parent hub
  * @emulp:	Returns pointer to emulator, or NULL if not found
  * @return 0 if found, -ve on error
  */
-int usb_emul_find(struct udevice *bus, ulong pipe, struct udevice **emulp);
+int usb_emul_find(struct udevice *bus, ulong pipe, int port1,
+		  struct udevice **emulp);
 
 /**
  * usb_emul_find_for_dev() - Find an emulator for a particular device