USB: add remove_id sysfs attr for usb drivers

Accroding commit 0994375e, which is adding remove_id sysfs attr
for pci drivers, for management tools dynamically bind/unbind
a pci/usb devices to a specified drivers; with this patch,
the management tools can be simplied.

And the original code didn't handle the failure of
usb_create_newid_file, fixed in this patch.

Signed-off-by: CHENG Renquan <rqcheng@smu.edu.sg>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2 files changed, 104 insertions, 9 deletions

diff --git a/Documentation/ABI/testing/sysfs-bus-usb b/Documentation/ABI/testing/sysfs-bus-usb
index 7772928ee48f..deb6b489e4e5 100644
--- a/Documentation/ABI/testing/sysfs-bus-usb
+++ b/Documentation/ABI/testing/sysfs-bus-usb
@@ -144,3 +144,16 @@ Description:
 
                 Write a 1 to force the device to disconnect
                 (equivalent to unplugging a wired USB device).
+
+What:           /sys/bus/usb/drivers/.../remove_id
+Date:           November 2009
+Contact:        CHENG Renquan <rqcheng@smu.edu.sg>
+Description:
+                Writing a device ID to this file will remove an ID
+                that was dynamically added via the new_id sysfs entry.
+                The format for the device ID is:
+                idVendor idProduct.     After successfully
+                removing an ID, the driver will no longer support the
+                device.  This is useful to ensure auto probing won't
+                match the driver to the device.  For example:
+                # echo "046d c315" > /sys/bus/usb/drivers/foo/remove_id
diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index 7a05bab73960..60a45f1e3a67 100644
--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -83,6 +83,47 @@ static ssize_t store_new_id(struct device_driver *driver,
 }
 static DRIVER_ATTR(new_id, S_IWUSR, NULL, store_new_id);
 
+/**
+ * store_remove_id - remove a USB device ID from this driver
+ * @driver: target device driver
+ * @buf: buffer for scanning device ID data
+ * @count: input size
+ *
+ * Removes a dynamic usb device ID from this driver.
+ */
+static ssize_t
+store_remove_id(struct device_driver *driver, const char *buf, size_t count)
+{
+        struct usb_dynid *dynid, *n;
+        struct usb_driver *usb_driver = to_usb_driver(driver);
+        u32 idVendor = 0;
+        u32 idProduct = 0;
+        int fields = 0;
+        int retval = 0;
+
+        fields = sscanf(buf, "%x %x", &idVendor, &idProduct);
+        if (fields < 2)
+                return -EINVAL;
+
+        spin_lock(&usb_driver->dynids.lock);
+        list_for_each_entry_safe(dynid, n, &usb_driver->dynids.list, node) {
+                struct usb_device_id *id = &dynid->id;
+                if ((id->idVendor == idVendor) &&
+                    (id->idProduct == idProduct)) {
+                        list_del(&dynid->node);
+                        kfree(dynid);
+                        retval = 0;
+                        break;
+                }
+        }
+        spin_unlock(&usb_driver->dynids.lock);
+
+        if (retval)
+                return retval;
+        return count;
+}
+static DRIVER_ATTR(remove_id, S_IWUSR, NULL, store_remove_id);
+
 static int usb_create_newid_file(struct usb_driver *usb_drv)
 {
         int error = 0;
@@ -107,6 +148,21 @@ static void usb_remove_newid_file(struct usb_driver *usb_drv)
                                    &driver_attr_new_id);
 }
 
+static int
+usb_create_removeid_file(struct usb_driver *drv)
+{
+        int error = 0;
+        if (drv->probe != NULL)
+                error = driver_create_file(&drv->drvwrap.driver,
+                                &driver_attr_remove_id);
+        return error;
+}
+
+static void usb_remove_removeid_file(struct usb_driver *drv)
+{
+        driver_remove_file(&drv->drvwrap.driver, &driver_attr_remove_id);
+}
+
 static void usb_free_dynids(struct usb_driver *usb_drv)
 {
         struct usb_dynid *dynid, *n;
@@ -128,6 +184,16 @@ static void usb_remove_newid_file(struct usb_driver *usb_drv)
 {
 }
 
+static int
+usb_create_removeid_file(struct usb_driver *drv)
+{
+        return 0;
+}
+
+static void usb_remove_removeid_file(struct usb_driver *drv)
+{
+}
+
 static inline void usb_free_dynids(struct usb_driver *usb_drv)
 {
 }
@@ -774,19 +840,34 @@ int usb_register_driver(struct usb_driver *new_driver, struct module *owner,
         INIT_LIST_HEAD(&new_driver->dynids.list);
 
         retval = driver_register(&new_driver->drvwrap.driver);
+        if (retval)
+                goto out;
 
-        if (!retval) {
-                pr_info("%s: registered new interface driver %s\n",
+        usbfs_update_special();
+
+        retval = usb_create_newid_file(new_driver);
+        if (retval)
+                goto out_newid;
+
+        retval = usb_create_removeid_file(new_driver);
+        if (retval)
+                goto out_removeid;
+
+        pr_info("%s: registered new interface driver %s\n",
                         usbcore_name, new_driver->name);
-                usbfs_update_special();
-                usb_create_newid_file(new_driver);
-        } else {
-                printk(KERN_ERR "%s: error %d registering interface "
-                        "       driver %s\n",
-                        usbcore_name, retval, new_driver->name);
-        }
 
+out:
         return retval;
+
+out_removeid:
+        usb_remove_newid_file(new_driver);
+out_newid:
+        driver_unregister(&new_driver->drvwrap.driver);
+
+        printk(KERN_ERR "%s: error %d registering interface "
+                        "       driver %s\n",
+                        usbcore_name, retval, new_driver->name);
+        goto out;
 }
 EXPORT_SYMBOL_GPL(usb_register_driver);
 
@@ -806,6 +887,7 @@ void usb_deregister(struct usb_driver *driver)
         pr_info("%s: deregistering interface driver %s\n",
                         usbcore_name, driver->name);
 
+        usb_remove_removeid_file(driver);
         usb_remove_newid_file(driver);
         usb_free_dynids(driver);
         driver_unregister(&driver->drvwrap.driver);