1 files changed, 62 insertions, 39 deletions

diff --git a/include/uapi/linux/uhid.h b/include/uapi/linux/uhid.h
index 0a08f2bbe642..116536eeae62 100644
--- a/include/uapi/linux/uhid.h
+++ b/include/uapi/linux/uhid.h
@@ -24,37 +24,21 @@
 #include <linux/hid.h>
 
 enum uhid_event_type {
-        UHID_CREATE,
+        __UHID_LEGACY_CREATE,
         UHID_DESTROY,
         UHID_START,
         UHID_STOP,
         UHID_OPEN,
         UHID_CLOSE,
         UHID_OUTPUT,
-        UHID_OUTPUT_EV,                 /* obsolete! */
-        UHID_INPUT,
-        UHID_FEATURE,                   /* obsolete! use UHID_GET_REPORT */
-        UHID_GET_REPORT = UHID_FEATURE,
-        UHID_FEATURE_ANSWER,            /* obsolete! use UHID_GET_REPORT_REPLY */
-        UHID_GET_REPORT_REPLY = UHID_FEATURE_ANSWER,
+        __UHID_LEGACY_OUTPUT_EV,
+        __UHID_LEGACY_INPUT,
+        UHID_GET_REPORT,
+        UHID_GET_REPORT_REPLY,
         UHID_CREATE2,
         UHID_INPUT2,
 };
 
-struct uhid_create_req {
-        __u8 name[128];
-        __u8 phys[64];
-        __u8 uniq[64];
-        __u8 __user *rd_data;
-        __u16 rd_size;
-
-        __u16 bus;
-        __u32 vendor;
-        __u32 product;
-        __u32 version;
-        __u32 country;
-} __attribute__((__packed__));
-
 struct uhid_create2_req {
         __u8 name[128];
         __u8 phys[64];
@@ -76,24 +60,67 @@ enum uhid_report_type {
         UHID_INPUT_REPORT,
 };
 
-struct uhid_input_req {
+struct uhid_input2_req {
+        __u16 size;
+        __u8 data[UHID_DATA_MAX];
+} __attribute__((__packed__));
+
+struct uhid_output_req {
         __u8 data[UHID_DATA_MAX];
         __u16 size;
+        __u8 rtype;
 } __attribute__((__packed__));
 
-struct uhid_input2_req {
+struct uhid_get_report_req {
+        __u32 id;
+        __u8 rnum;
+        __u8 rtype;
+} __attribute__((__packed__));
+
+struct uhid_get_report_reply_req {
+        __u32 id;
+        __u16 err;
         __u16 size;
         __u8 data[UHID_DATA_MAX];
 } __attribute__((__packed__));
 
-struct uhid_output_req {
+/*
+ * Compat Layer
+ * All these commands and requests are obsolete. You should avoid using them in
+ * new code. We support them for backwards-compatibility, but you might not get
+ * access to new feature in case you use them.
+ */
+
+enum uhid_legacy_event_type {
+        UHID_CREATE                     = __UHID_LEGACY_CREATE,
+        UHID_OUTPUT_EV                  = __UHID_LEGACY_OUTPUT_EV,
+        UHID_INPUT                      = __UHID_LEGACY_INPUT,
+        UHID_FEATURE                    = UHID_GET_REPORT,
+        UHID_FEATURE_ANSWER             = UHID_GET_REPORT_REPLY,
+};
+
+/* Obsolete! Use UHID_CREATE2. */
+struct uhid_create_req {
+        __u8 name[128];
+        __u8 phys[64];
+        __u8 uniq[64];
+        __u8 __user *rd_data;
+        __u16 rd_size;
+
+        __u16 bus;
+        __u32 vendor;
+        __u32 product;
+        __u32 version;
+        __u32 country;
+} __attribute__((__packed__));
+
+/* Obsolete! Use UHID_INPUT2. */
+struct uhid_input_req {
         __u8 data[UHID_DATA_MAX];
         __u16 size;
-        __u8 rtype;
 } __attribute__((__packed__));
 
-/* Obsolete! Newer kernels will no longer send these events but instead convert
- * it into raw output reports via UHID_OUTPUT. */
+/* Obsolete! Kernel uses UHID_OUTPUT exclusively now. */
 struct uhid_output_ev_req {
         __u16 type;
         __u16 code;
@@ -107,12 +134,6 @@ struct uhid_feature_req {
         __u8 rtype;
 } __attribute__((__packed__));
 
-struct uhid_get_report_req {
-        __u32 id;
-        __u8 rnum;
-        __u8 rtype;
-} __attribute__((__packed__));
-
 /* Obsolete! Use ABI compatible UHID_GET_REPORT_REPLY. */
 struct uhid_feature_answer_req {
         __u32 id;
@@ -121,12 +142,14 @@ struct uhid_feature_answer_req {
         __u8 data[UHID_DATA_MAX];
 } __attribute__((__packed__));
 
-struct uhid_get_report_reply_req {
-        __u32 id;
-        __u16 err;
-        __u16 size;
-        __u8 data[UHID_DATA_MAX];
-} __attribute__((__packed__));
+/*
+ * UHID Events
+ * All UHID events from and to the kernel are encoded as "struct uhid_event".
+ * The "type" field contains a UHID_* type identifier. All payload depends on
+ * that type and can be accessed via ev->u.XYZ accordingly.
+ * If user-space writes short events, they're extended with 0s by the kernel. If
+ * the kernel writes short events, user-space shall extend them with 0s.
+ */
 
 struct uhid_event {
         __u32 type;