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Date:   Sun, 06 Oct 2019 01:04:39 +0000
To:     "linux-input@vger.kernel.org" <linux-input@vger.kernel.org>
From:   Mazin Rezk <mnrzk@protonmail.com>
Cc:     "benjamin.tissoires@redhat.com" <benjamin.tissoires@redhat.com>,
        "jikos@kernel.org" <jikos@kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "lains@archlinux.org" <lains@archlinux.org>,
        "mnrzk@protonmail.com" <mnrzk@protonmail.com>
Reply-To: Mazin Rezk <mnrzk@protonmail.com>
Subject: [PATCH v3 3/4] HID: logitech: Add feature 0x0001: FeatureSet
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This patch adds support for the 0x0001 (FeatureSet) feature. This feature
is used to look up the feature ID of a feature index on a device and list
the total count of features on the device.

I also added the hidpp20_get_features function which iterates through all
feature indexes on the device and stores a map of them in features an
hidpp_device struct. This function runs when an HID++ 2.0 device is probed.

Signed-off-by: Mazin Rezk <mnrzk@protonmail.com>
---
 drivers/hid/hid-logitech-hidpp.c | 92 ++++++++++++++++++++++++++++++++
 1 file changed, 92 insertions(+)

diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hi=
dpp.c
index a0efa8a43213..64ac94c581aa 100644
--- a/drivers/hid/hid-logitech-hidpp.c
+++ b/drivers/hid/hid-logitech-hidpp.c
@@ -190,6 +190,9 @@ struct hidpp_device {

 =09struct hidpp_battery battery;
 =09struct hidpp_scroll_counter vertical_wheel_counter;
+
+=09u16 *features;
+=09u8 feature_count;
 };

 /* HID++ 1.0 error codes */
@@ -911,6 +914,84 @@ static int hidpp_root_get_protocol_version(struct hidp=
p_device *hidpp)
 =09return 0;
 }

+/* -----------------------------------------------------------------------=
--- */
+/* 0x0001: FeatureSet                                                     =
    */
+/* -----------------------------------------------------------------------=
--- */
+
+#define HIDPP_PAGE_FEATURESET=09=09=09=090x0001
+
+#define CMD_FEATURESET_GET_COUNT=09=09=090x00
+#define CMD_FEATURESET_GET_FEATURE=09=09=090x11
+
+static int hidpp20_featureset_get_feature(struct hidpp_device *hidpp,
+=09u8 featureset_index, u8 feature_index, u16 *feature_id)
+{
+=09struct hidpp_report response;
+=09int ret;
+
+=09ret =3D hidpp_send_fap_command_sync(hidpp, featureset_index,
+=09=09CMD_FEATURESET_GET_FEATURE, &feature_index, 1, &response);
+
+=09if (ret)
+=09=09return ret;
+
+=09*feature_id =3D (response.fap.params[0] << 8) | response.fap.params[1];
+
+=09return ret;
+}
+
+static int hidpp20_featureset_get_count(struct hidpp_device *hidpp,
+=09u8 feature_index, u8 *count)
+{
+=09struct hidpp_report response;
+=09int ret;
+
+=09ret =3D hidpp_send_fap_command_sync(hidpp, feature_index,
+=09=09CMD_FEATURESET_GET_COUNT, NULL, 0, &response);
+
+=09if (ret)
+=09=09return ret;
+
+=09*count =3D response.fap.params[0];
+
+=09return ret;
+}
+
+static int hidpp20_get_features(struct hidpp_device *hidpp)
+{
+=09int ret;
+=09u8 featureset_index, featureset_type;
+=09u8 i;
+
+=09hidpp->feature_count =3D 0;
+
+=09ret =3D hidpp_root_get_feature(hidpp, HIDPP_PAGE_FEATURESET,
+=09=09=09=09     &featureset_index, &featureset_type);
+
+=09if (ret =3D=3D -ENOENT) {
+=09=09hid_warn(hidpp->hid_dev, "Unable to retrieve feature set.");
+=09=09return 0;
+=09}
+
+=09if (ret)
+=09=09return ret;
+
+=09ret =3D hidpp20_featureset_get_count(hidpp, featureset_index,
+=09=09&hidpp->feature_count);
+
+=09if (ret)
+=09=09return ret;
+
+=09hidpp->features =3D devm_kzalloc(&hidpp->hid_dev->dev,
+=09=09=09hidpp->feature_count * sizeof(u16), GFP_KERNEL);
+
+=09for (i =3D 0; i < hidpp->feature_count && !ret; i++)
+=09=09ret =3D hidpp20_featureset_get_feature(hidpp, featureset_index,
+=09=09=09=09i, &(hidpp->features[i]));
+
+=09return ret;
+}
+
 /* -----------------------------------------------------------------------=
--- */
 /* 0x0005: GetDeviceNameType                                              =
    */
 /* -----------------------------------------------------------------------=
--- */
@@ -3625,6 +3706,17 @@ static int hidpp_probe(struct hid_device *hdev, cons=
t struct hid_device_id *id)
 =09=09hidpp_overwrite_name(hdev);
 =09}

+=09/* Cache feature indexes and IDs to check reports faster */
+=09if (hidpp->protocol_major >=3D 2) {
+=09=09if (hidpp20_get_features(hidpp)) {
+=09=09=09hid_err(hdev, "%s:hidpp20_get_features returned error\n",
+=09=09=09=09__func__);
+=09=09=09goto hid_hw_init_fail;
+=09=09}
+=09} else {
+=09=09hidpp->feature_count =3D 0;
+=09}
+
 =09if (connected && (hidpp->quirks & HIDPP_QUIRK_CLASS_WTP)) {
 =09=09ret =3D wtp_get_config(hidpp);
 =09=09if (ret)
--
2.23.0