Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753992Ab2KGQlN (ORCPT ); Wed, 7 Nov 2012 11:41:13 -0500 Received: from mail-ee0-f46.google.com ([74.125.83.46]:33927 "EHLO mail-ee0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752539Ab2KGQh6 (ORCPT ); Wed, 7 Nov 2012 11:37:58 -0500 From: Benjamin Tissoires To: "benjamin.tissoires" , Dmitry Torokhov , Henrik Rydberg , Jiri Kosina , Stephane Chatty , linux-input@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 03/13] HID: core: fix unit exponent parsing Date: Wed, 7 Nov 2012 17:37:26 +0100 Message-Id: <1352306256-12180-4-git-send-email-benjamin.tissoires@gmail.com> X-Mailer: git-send-email 1.7.11.7 In-Reply-To: <1352306256-12180-1-git-send-email-benjamin.tissoires@gmail.com> References: <1352306256-12180-1-git-send-email-benjamin.tissoires@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3591 Lines: 111 HID spec details special values for the HID field unit exponent. Basically, the range [0x8..0xf] correspond to [-8..-1], so this is a standard two's complement on a half-byte. Signed-off-by: Benjamin Tissoires --- drivers/hid/hid-core.c | 16 +++++++++++++++- drivers/hid/hid-input.c | 13 +++++++++---- include/linux/hid.h | 1 + 3 files changed, 25 insertions(+), 5 deletions(-) diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c index 3d0da29..9da3007 100644 --- a/drivers/hid/hid-core.c +++ b/drivers/hid/hid-core.c @@ -315,6 +315,7 @@ static s32 item_sdata(struct hid_item *item) static int hid_parser_global(struct hid_parser *parser, struct hid_item *item) { + __u32 raw_value; switch (item->tag) { case HID_GLOBAL_ITEM_TAG_PUSH: @@ -365,7 +366,14 @@ static int hid_parser_global(struct hid_parser *parser, struct hid_item *item) return 0; case HID_GLOBAL_ITEM_TAG_UNIT_EXPONENT: - parser->global.unit_exponent = item_sdata(item); + /* Units exponent negative numbers are given through a + * two's complement. + * See "6.2.2.7 Global Items" for more information. */ + raw_value = item_udata(item); + if (!(raw_value & 0xfffffff0)) + parser->global.unit_exponent = hid_snto32(raw_value, 4); + else + parser->global.unit_exponent = raw_value; return 0; case HID_GLOBAL_ITEM_TAG_UNIT: @@ -865,6 +873,12 @@ static s32 snto32(__u32 value, unsigned n) return value & (1 << (n - 1)) ? value | (-1 << n) : value; } +s32 hid_snto32(__u32 value, unsigned n) +{ + return snto32(value, n); +} +EXPORT_SYMBOL_GPL(hid_snto32); + /* * Convert a signed 32-bit integer to a signed n-bit integer. */ diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c index 67044f3..7015080 100644 --- a/drivers/hid/hid-input.c +++ b/drivers/hid/hid-input.c @@ -192,7 +192,6 @@ static int hidinput_setkeycode(struct input_dev *dev, return -EINVAL; } - /** * hidinput_calc_abs_res - calculate an absolute axis resolution * @field: the HID report field to calculate resolution for @@ -235,17 +234,23 @@ __s32 hidinput_calc_abs_res(const struct hid_field *field, __u16 code) case ABS_MT_TOOL_Y: case ABS_MT_TOUCH_MAJOR: case ABS_MT_TOUCH_MINOR: - if (field->unit == 0x11) { /* If centimeters */ + if (field->unit & 0xffffff00) /* Not a length */ + return 0; + unit_exponent += hid_snto32(field->unit >> 4, 4) - 1; + switch (field->unit & 0xf) { + case 0x1: /* If centimeters */ /* Convert to millimeters */ unit_exponent += 1; - } else if (field->unit == 0x13) { /* If inches */ + break; + case 0x3: /* If inches */ /* Convert to millimeters */ prev = physical_extents; physical_extents *= 254; if (physical_extents < prev) return 0; unit_exponent -= 1; - } else { + break; + default: return 0; } break; diff --git a/include/linux/hid.h b/include/linux/hid.h index 9edb06c..a110a3e 100644 --- a/include/linux/hid.h +++ b/include/linux/hid.h @@ -754,6 +754,7 @@ int hid_connect(struct hid_device *hid, unsigned int connect_mask); void hid_disconnect(struct hid_device *hid); const struct hid_device_id *hid_match_id(struct hid_device *hdev, const struct hid_device_id *id); +s32 hid_snto32(__u32 value, unsigned n); /** * hid_map_usage - map usage input bits -- 1.7.11.7 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/