HID: Add device group to modalias

HID devices are only partially presented to userland.  Hotplugged
devices emit events containing a modalias based on the basic bus,
vendor and product entities. However, in practise a hid device can
depend on details such as a single usb interface or a particular item
in a report descriptor.

This patch adds a device group to the hid device id, and broadcasts it
using uevent and the device modalias.  The module alias generation is
modified to match. As a consequence, a device with a non-zero group
will be processed by the corresponding group driver instead of by the
generic hid driver.

Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
Acked-by: Benjamin Tissoires <benjamin.tissoires@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

1 files changed, 22 insertions, 2 deletions

diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 9ed4ff37dc2..cfcb69eb17d 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -1222,6 +1222,7 @@ static bool hid_match_one_id(struct hid_device *hdev,
 		const struct hid_device_id *id)
 {
 	return id->bus == hdev->bus &&
+		(id->group == HID_GROUP_ANY || id->group == hdev->group) &&
 		(id->vendor == HID_ANY_ID || id->vendor == hdev->vendor) &&
 		(id->product == HID_ANY_ID || id->product == hdev->product);
 }
@@ -1694,6 +1695,7 @@ static ssize_t store_new_id(struct device_driver *drv, const char *buf,
 		return -ENOMEM;
 
 	dynid->id.bus = bus;
+	dynid->id.group = HID_GROUP_ANY;
 	dynid->id.vendor = vendor;
 	dynid->id.product = product;
 	dynid->id.driver_data = driver_data;
@@ -1817,6 +1819,23 @@ static int hid_device_remove(struct device *dev)
 	return 0;
 }
 
+static ssize_t modalias_show(struct device *dev, struct device_attribute *a,
+			     char *buf)
+{
+	struct hid_device *hdev = container_of(dev, struct hid_device, dev);
+	int len;
+
+	len = snprintf(buf, PAGE_SIZE, "hid:b%04Xg%04Xv%08Xp%08X\n",
+		       hdev->bus, hdev->group, hdev->vendor, hdev->product);
+
+	return (len >= PAGE_SIZE) ? (PAGE_SIZE - 1) : len;
+}
+
+static struct device_attribute hid_dev_attrs[] = {
+	__ATTR_RO(modalias),
+	__ATTR_NULL,
+};
+
 static int hid_uevent(struct device *dev, struct kobj_uevent_env *env)
 {
 	struct hid_device *hdev = container_of(dev, struct hid_device, dev);
@@ -1834,8 +1853,8 @@ static int hid_uevent(struct device *dev, struct kobj_uevent_env *env)
 	if (add_uevent_var(env, "HID_UNIQ=%s", hdev->uniq))
 		return -ENOMEM;
 
-	if (add_uevent_var(env, "MODALIAS=hid:b%04Xv%08Xp%08X",
-			hdev->bus, hdev->vendor, hdev->product))
+	if (add_uevent_var(env, "MODALIAS=hid:b%04Xg%04Xv%08Xp%08X",
+			   hdev->bus, hdev->group, hdev->vendor, hdev->product))
 		return -ENOMEM;
 
 	return 0;
@@ -1843,6 +1862,7 @@ static int hid_uevent(struct device *dev, struct kobj_uevent_env *env)
 
 static struct bus_type hid_bus_type = {
 	.name		= "hid",
+	.dev_attrs	= hid_dev_attrs,
 	.match		= hid_bus_match,
 	.probe		= hid_device_probe,
 	.remove		= hid_device_remove,