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Subject[PATCH v3] HID: core: check whether usage page item is after usage id item
Date
From: Candle Sun <candle.sun@unisoc.com>

Upstream commit 58e75155009c ("HID: core: move Usage Page concatenation
to Main item") adds support for Usage Page item after Usage ID items
(such as keyboards manufactured by Primax).

Usage Page concatenation in Main item works well for following report
descriptor patterns:

USAGE_PAGE (Keyboard) 05 07
USAGE_MINIMUM (Keyboard LeftControl) 19 E0
USAGE_MAXIMUM (Keyboard Right GUI) 29 E7
LOGICAL_MINIMUM (0) 15 00
LOGICAL_MAXIMUM (1) 25 01
REPORT_SIZE (1) 75 01
REPORT_COUNT (8) 95 08
INPUT (Data,Var,Abs) 81 02

-------------

USAGE_MINIMUM (Keyboard LeftControl) 19 E0
USAGE_MAXIMUM (Keyboard Right GUI) 29 E7
LOGICAL_MINIMUM (0) 15 00
LOGICAL_MAXIMUM (1) 25 01
REPORT_SIZE (1) 75 01
REPORT_COUNT (8) 95 08
USAGE_PAGE (Keyboard) 05 07
INPUT (Data,Var,Abs) 81 02

But it makes the parser act wrong for the following report
descriptor pattern(such as some Gamepads):

USAGE_PAGE (Button) 05 09
USAGE (Button 1) 09 01
USAGE (Button 2) 09 02
USAGE (Button 4) 09 04
USAGE (Button 5) 09 05
USAGE (Button 7) 09 07
USAGE (Button 8) 09 08
USAGE (Button 14) 09 0E
USAGE (Button 15) 09 0F
USAGE (Button 13) 09 0D
USAGE_PAGE (Consumer Devices) 05 0C
USAGE (Back) 0a 24 02
USAGE (HomePage) 0a 23 02
LOGICAL_MINIMUM (0) 15 00
LOGICAL_MAXIMUM (1) 25 01
REPORT_SIZE (1) 75 01
REPORT_COUNT (11) 95 0B
INPUT (Data,Var,Abs) 81 02

With Usage Page concatenation in Main item, parser recognizes all the
11 Usages as consumer keys, it is not the HID device's real intention.

This patch adds usage_page_last to flag whether Usage Page is after
Usage ID items. usage_page_last is false default, it is set as true
once Usage Page item is encountered and is reverted by next Usage ID
item.

Usage Page concatenation on the currently defined Usage Page will do
firstly in Local parsing when Usage ID items encountered.

When Main item is parsing, concatenation will do again with last
defined Usage Page if usage_page_last flag is true.

Signed-off-by: Candle Sun <candle.sun@unisoc.com>
Signed-off-by: Nianfu Bai <nianfu.bai@unisoc.com>
---
Changes in v3:
- Rework the GET_COMPLETE_USAGE macro as static complete_usage()
function
- Add some code comments for usage_page_last

Changes in v2:
- Update patch title
- Add GET_COMPLETE_USAGE macro
- Change the logic of checking whether to concatenate usage page again
in main parsing
---
drivers/hid/hid-core.c | 42 +++++++++++++++++++++++++++++++++++++-----
include/linux/hid.h | 1 +
2 files changed, 38 insertions(+), 5 deletions(-)

diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 3eaee2c37931..779b7798dae8 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -211,6 +211,18 @@ static unsigned hid_lookup_collection(struct hid_parser *parser, unsigned type)
return 0; /* we know nothing about this usage type */
}

+/*
+ * Concatenate usage which defines 16 bits or less with the
+ * currently defined usage page to form a 32 bit usage
+ */
+
+static void complete_usage(struct hid_parser *parser, unsigned int index)
+{
+ parser->local.usage[index] &= 0xFFFF;
+ parser->local.usage[index] |=
+ (parser->global.usage_page & 0xFFFF) << 16;
+}
+
/*
* Add a usage to the temporary parser table.
*/
@@ -221,7 +233,18 @@ static int hid_add_usage(struct hid_parser *parser, unsigned usage, u8 size)
hid_err(parser->device, "usage index exceeded\n");
return -1;
}
- parser->local.usage[parser->local.usage_index] = usage;
+
+ /*
+ * If Usage item only includes usage id, concatenate it with
+ * currently defined usage page and clear usage_page_last flag
+ */
+ if (size <= 2) {
+ parser->local.usage_page_last = false;
+ complete_usage(parser, parser->local.usage_index);
+ } else {
+ parser->local.usage[parser->local.usage_index] = usage;
+ }
+
parser->local.usage_size[parser->local.usage_index] = size;
parser->local.collection_index[parser->local.usage_index] =
parser->collection_stack_ptr ?
@@ -366,6 +389,8 @@ static int hid_parser_global(struct hid_parser *parser, struct hid_item *item)

case HID_GLOBAL_ITEM_TAG_USAGE_PAGE:
parser->global.usage_page = item_udata(item);
+ /* Regard Usage Page is after Usage ID items */
+ parser->local.usage_page_last = true;
return 0;

case HID_GLOBAL_ITEM_TAG_LOGICAL_MINIMUM:
@@ -543,13 +568,20 @@ static int hid_parser_local(struct hid_parser *parser, struct hid_item *item)
* usage value."
*/

-static void hid_concatenate_usage_page(struct hid_parser *parser)
+static void hid_concatenate_last_usage_page(struct hid_parser *parser)
{
int i;

+ /*
+ * Concatenate usage page again only on detecting some Usage Page
+ * is really after Usage ID items
+ */
+ if (!parser->local.usage_page_last)
+ return;
+
for (i = 0; i < parser->local.usage_index; i++)
if (parser->local.usage_size[i] <= 2)
- parser->local.usage[i] += parser->global.usage_page << 16;
+ complete_usage(parser, i);
}

/*
@@ -561,7 +593,7 @@ static int hid_parser_main(struct hid_parser *parser, struct hid_item *item)
__u32 data;
int ret;

- hid_concatenate_usage_page(parser);
+ hid_concatenate_last_usage_page(parser);

data = item_udata(item);

@@ -772,7 +804,7 @@ static int hid_scan_main(struct hid_parser *parser, struct hid_item *item)
__u32 data;
int i;

- hid_concatenate_usage_page(parser);
+ hid_concatenate_last_usage_page(parser);

data = item_udata(item);

diff --git a/include/linux/hid.h b/include/linux/hid.h
index cd41f209043f..2e0ea2f7ec5c 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -412,6 +412,7 @@ struct hid_local {
unsigned usage_minimum;
unsigned delimiter_depth;
unsigned delimiter_branch;
+ bool usage_page_last; /* whether usage page is after usage id */
};

/*
--
2.17.1
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