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Subject[PATCH v2 1/6] hid: Add device group to modalias
Date
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>
---
drivers/hid/hid-core.c | 24 ++++++++++++++++++++++--
include/linux/hid.h | 1 +
include/linux/mod_devicetable.h | 3 ++-
scripts/mod/file2alias.c | 2 ++
4 files changed, 27 insertions(+), 3 deletions(-)
diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 9ed4ff3..cfcb69e 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,
diff --git a/include/linux/hid.h b/include/linux/hid.h
index d8e7cc7..a0e27dd 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -476,6 +476,7 @@ struct hid_device { /* device report descriptor */
unsigned maxcollection; /* Number of parsed collections */
unsigned maxapplication; /* Number of applications */
__u16 bus; /* BUS ID */
+ __u16 group; /* Report group */
__u32 vendor; /* Vendor ID */
__u32 product; /* Product ID */
__u32 version; /* HID version */
diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
index 501da4c..55ed0b0 100644
--- a/include/linux/mod_devicetable.h
+++ b/include/linux/mod_devicetable.h
@@ -132,10 +132,11 @@ struct usb_device_id {
#define USB_DEVICE_ID_MATCH_INT_PROTOCOL 0x0200

#define HID_ANY_ID (~0)
+#define HID_GROUP_ANY 0x0000

struct hid_device_id {
__u16 bus;
- __u16 pad1;
+ __u16 group;
__u32 vendor;
__u32 product;
kernel_ulong_t driver_data
diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c
index 8e730cc..fe967ce 100644
--- a/scripts/mod/file2alias.c
+++ b/scripts/mod/file2alias.c
@@ -336,10 +336,12 @@ static int do_hid_entry(const char *filename,
struct hid_device_id *id, char *alias)
{
id->bus = TO_NATIVE(id->bus);
+ id->group = TO_NATIVE(id->group);
id->vendor = TO_NATIVE(id->vendor);
id->product = TO_NATIVE(id->product);

sprintf(alias, "hid:b%04X", id->bus);
+ ADD(alias, "g", id->group != HID_GROUP_ANY, id->group);
ADD(alias, "v", id->vendor != HID_ANY_ID, id->vendor);
ADD(alias, "p", id->product != HID_ANY_ID, id->product);

--
1.7.10


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