queue-4.4/hid-core-move-usage-page-concatenation-to-main-item.patch

   1 From 51878761d65fa02c43a15d339bd1a756bbf6a03d Mon Sep 17 00:00:00 2001
   2 From: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
   3 Date: Wed, 27 Mar 2019 11:18:48 +0100
   4 Subject: HID: core: move Usage Page concatenation to Main item
   5
   6 [ Upstream commit 58e75155009cc800005629955d3482f36a1e0eec ]
   7
   8 As seen on some USB wireless keyboards manufactured by Primax, the HID
   9 parser was using some assumptions that are not always true. In this case
  10 it's s the fact that, inside the scope of a main item, an Usage Page
  11 will always precede an Usage.
  12
  13 The spec is not pretty clear as 6.2.2.7 states "Any usage that follows
  14 is interpreted as a Usage ID and concatenated with the Usage Page".
  15 While 6.2.2.8 states "When the parser encounters a main item it
  16 concatenates the last declared Usage Page with a Usage to form a
  17 complete usage value." Being somewhat contradictory it was decided to
  18 match Window's implementation, which follows 6.2.2.8.
  19
  20 In summary, the patch moves the Usage Page concatenation from the local
  21 item parsing function to the main item parsing function.
  22
  23 Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
  24 Reviewed-by: Terry Junge <terry.junge@poly.com>
  25 Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
  26 Signed-off-by: Sasha Levin <sashal@kernel.org>
  27 ---
  28  drivers/hid/hid-core.c | 36 ++++++++++++++++++++++++------------
  29  include/linux/hid.h    |  1 +
  30  2 files changed, 25 insertions(+), 12 deletions(-)
  31
  32 diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
  33 index 4564ecf711815..9b2b41d683dea 100644
  34 --- a/drivers/hid/hid-core.c
  35 +++ b/drivers/hid/hid-core.c
  36 @@ -200,13 +200,14 @@ static unsigned hid_lookup_collection(struct hid_parser *parser, unsigned type)
  37   * Add a usage to the temporary parser table.
  38   */
  39
  40 -static int hid_add_usage(struct hid_parser *parser, unsigned usage)
  41 +static int hid_add_usage(struct hid_parser *parser, unsigned usage, u8 size)
  42  {
  43         if (parser->local.usage_index >= HID_MAX_USAGES) {
  44                 hid_err(parser->device, "usage index exceeded\n");
  45                 return -1;
  46         }
  47         parser->local.usage[parser->local.usage_index] = usage;
  48 +       parser->local.usage_size[parser->local.usage_index] = size;
  49         parser->local.collection_index[parser->local.usage_index] =
  50                 parser->collection_stack_ptr ?
  51                 parser->collection_stack[parser->collection_stack_ptr - 1] : 0;
  52 @@ -463,10 +464,7 @@ static int hid_parser_local(struct hid_parser *parser, struct hid_item *item)
  53                         return 0;
  54                 }
  55
  56 -               if (item->size <= 2)
  57 -                       data = (parser->global.usage_page << 16) + data;
  58 -
  59 -               return hid_add_usage(parser, data);
  60 +               return hid_add_usage(parser, data, item->size);
  61
  62         case HID_LOCAL_ITEM_TAG_USAGE_MINIMUM:
  63
  64 @@ -475,9 +473,6 @@ static int hid_parser_local(struct hid_parser *parser, struct hid_item *item)
  65                         return 0;
  66                 }
  67
  68 -               if (item->size <= 2)
  69 -                       data = (parser->global.usage_page << 16) + data;
  70 -
  71                 parser->local.usage_minimum = data;
  72                 return 0;
  73
  74 @@ -488,9 +483,6 @@ static int hid_parser_local(struct hid_parser *parser, struct hid_item *item)
  75                         return 0;
  76                 }
  77
  78 -               if (item->size <= 2)
  79 -                       data = (parser->global.usage_page << 16) + data;
  80 -
  81                 count = data - parser->local.usage_minimum;
  82                 if (count + parser->local.usage_index >= HID_MAX_USAGES) {
  83                         /*
  84 @@ -510,7 +502,7 @@ static int hid_parser_local(struct hid_parser *parser, struct hid_item *item)
  85                 }
  86
  87                 for (n = parser->local.usage_minimum; n <= data; n++)
  88 -                       if (hid_add_usage(parser, n)) {
  89 +                       if (hid_add_usage(parser, n, item->size)) {
  90                                 dbg_hid("hid_add_usage failed\n");
  91                                 return -1;
  92                         }
  93 @@ -524,6 +516,22 @@ static int hid_parser_local(struct hid_parser *parser, struct hid_item *item)
  94         return 0;
  95  }
  96
  97 +/*
  98 + * Concatenate Usage Pages into Usages where relevant:
  99 + * As per specification, 6.2.2.8: "When the parser encounters a main item it
 100 + * concatenates the last declared Usage Page with a Usage to form a complete
 101 + * usage value."
 102 + */
 103 +
 104 +static void hid_concatenate_usage_page(struct hid_parser *parser)
 105 +{
 106 +       int i;
 107 +
 108 +       for (i = 0; i < parser->local.usage_index; i++)
 109 +               if (parser->local.usage_size[i] <= 2)
 110 +                       parser->local.usage[i] += parser->global.usage_page << 16;
 111 +}
 112 +
 113  /*
 114   * Process a main item.
 115   */
 116 @@ -533,6 +541,8 @@ static int hid_parser_main(struct hid_parser *parser, struct hid_item *item)
 117         __u32 data;
 118         int ret;
 119
 120 +       hid_concatenate_usage_page(parser);
 121 +
 122         data = item_udata(item);
 123
 124         switch (item->tag) {
 125 @@ -746,6 +756,8 @@ static int hid_scan_main(struct hid_parser *parser, struct hid_item *item)
 126         __u32 data;
 127         int i;
 128
 129 +       hid_concatenate_usage_page(parser);
 130 +
 131         data = item_udata(item);
 132
 133         switch (item->tag) {
 134 diff --git a/include/linux/hid.h b/include/linux/hid.h
 135 index fd86687f81196..5f31318851366 100644
 136 --- a/include/linux/hid.h
 137 +++ b/include/linux/hid.h
 138 @@ -372,6 +372,7 @@ struct hid_global {
 139
 140  struct hid_local {
 141         unsigned usage[HID_MAX_USAGES]; /* usage array */
 142 +       u8 usage_size[HID_MAX_USAGES]; /* usage size array */
 143         unsigned collection_index[HID_MAX_USAGES]; /* collection index array */
 144         unsigned usage_index;
 145         unsigned usage_minimum;
 146 --
 147 2.20.1
 148