[RFC 4/5] HID: hid-logitech-hidpp: Add range sysfs for Logitech G920

[Simon Wood <simon@mungewell.org>]

The G920 can adjust the amount of 'turn' it permits, this patch adds
a sysfs file 'range' to control this.
---
 drivers/hid/hid-logitech-hidpp.c | 140 ++++++++++++++++++++++++++++++++++++++-
 1 file changed, 139 insertions(+), 1 deletion(-)

diff --git a/drivers/hid/hid-logitech-hidpp.c b/drivers/hid/hid-logitech-hidpp.c
index 76d7267..db05f55 100644
--- a/drivers/hid/hid-logitech-hidpp.c
+++ b/drivers/hid/hid-logitech-hidpp.c
@@ -1170,6 +1170,133 @@ static int m560_input_mapping(struct hid_device *hdev, struct hid_input *hi,
 	return -1;
 }
 
+/* ------------------------------------------------------------------------- */
+/* Logitech G920 Driving Force Racing Wheel for Xbox One                     */
+/* ------------------------------------------------------------------------- */
+
+#define HIDPP_PAGE_G920_FORCE_FEEDBACK			0x8123
+
+/* Using session ID = 1 */
+#define CMD_G920_FORCE_GET_APERTURE			0x51
+#define CMD_G920_FORCE_SET_APERTURE			0x61
+
+struct g920_private_data {
+	u8 force_feature;
+	u16 range;
+};
+
+#define to_hid_device(pdev) container_of(pdev, struct hid_device, dev)
+
+static ssize_t g920_range_show(struct device *dev, struct device_attribute *attr,
+				char *buf)
+{
+	struct hid_device *hid = to_hid_device(dev);
+	struct hidpp_device *hidpp = hid_get_drvdata(hid);
+	struct g920_private_data *pdata;
+
+	pdata = hidpp->private_data;
+	if (!pdata) {
+		hid_err(hid, "Private driver data not found!\n");
+		return -EINVAL;
+	}
+
+	return scnprintf(buf, PAGE_SIZE, "%u\n", pdata->range);
+}
+
+static ssize_t g920_range_store(struct device *dev, struct device_attribute *attr,
+				 const char *buf, size_t count)
+{
+	struct hid_device *hid = to_hid_device(dev);
+	struct hidpp_device *hidpp = hid_get_drvdata(hid);
+	struct g920_private_data *pdata;
+	struct hidpp_report response;
+	u8 params[2];
+	int ret;
+	u16 range = simple_strtoul(buf, NULL, 10);
+
+	pdata = hidpp->private_data;
+	if (!pdata) {
+		hid_err(hid, "Private driver data not found!\n");
+		return -EINVAL;
+	}
+
+	if (range < 180)
+		range = 180;
+	else if (range > 900)
+		range = 900;
+
+	params[0] = range >> 8;
+	params[1] = range & 0x00FF;
+
+	ret = hidpp_send_fap_command_sync(hidpp, pdata->force_feature,
+		CMD_G920_FORCE_SET_APERTURE, params, 2, &response);
+	if (ret)
+		return ret;
+
+	pdata->range = range;
+	return count;
+}
+
+static DEVICE_ATTR(range, S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP | S_IROTH, g920_range_show, g920_range_store);
+
+static int g920_allocate(struct hid_device *hdev)
+{
+	struct hidpp_device *hidpp = hid_get_drvdata(hdev);
+	struct g920_private_data *pdata;
+
+	pdata = devm_kzalloc(&hdev->dev, sizeof(struct g920_private_data),
+			GFP_KERNEL);
+	if (!pdata)
+		return -ENOMEM;
+
+	hidpp->private_data = pdata;
+
+	return 0;
+}
+
+static int g920_get_config(struct hidpp_device *hidpp)
+{
+	struct g920_private_data *pdata = hidpp->private_data;
+	struct hidpp_report response;
+	u8 feature_type;
+	u8 feature_index;
+	int ret;
+
+	pdata = hidpp->private_data;
+	if (!pdata) {
+		hid_err(hidpp->hid_dev, "Private driver data not found!\n");
+		return -EINVAL;
+	}
+
+	/* Find feature and store for later use */
+	ret = hidpp_root_get_feature(hidpp, HIDPP_PAGE_G920_FORCE_FEEDBACK,
+		&feature_index, &feature_type);
+	if (ret)
+		return ret;
+
+	pdata->force_feature = feature_index;
+
+	/* Read current Range */
+	ret = hidpp_send_fap_command_sync(hidpp, feature_index,
+		CMD_G920_FORCE_GET_APERTURE, NULL, 0, &response);
+	if (ret > 0) {
+		hid_err(hidpp->hid_dev, "%s: received protocol error 0x%02x\n",
+			__func__, ret);
+		return -EPROTO;
+	}
+	if (ret)
+		return ret;
+
+	pdata->range = get_unaligned_be16(&response.fap.params[0]);
+
+	/* Create sysfs interface */
+	ret = device_create_file(&(hidpp->hid_dev->dev), &dev_attr_range);
+	if (ret)
+		hid_warn(hidpp->hid_dev, "Unable to create sysfs interface for \"range\", errno %d\n", ret);
+
+	return 0;
+}
+
 /* -------------------------------------------------------------------------- */
 /* Generic HID++ devices                                                      */
 /* -------------------------------------------------------------------------- */
@@ -1456,6 +1583,10 @@ static int hidpp_probe(struct hid_device *hdev, const struct hid_device_id *id)
 		ret = m560_allocate(hdev);
 		if (ret)
 			goto allocate_fail;
+	} else if (hidpp->quirks & HIDPP_QUIRK_CLASS_G920) {
+		ret = g920_allocate(hdev);
+		if (ret)
+			goto allocate_fail;
 	}
 
 	INIT_WORK(&hidpp->work, delayed_work_cb);
@@ -1509,6 +1640,10 @@ static int hidpp_probe(struct hid_device *hdev, const struct hid_device_id *id)
 		ret = wtp_get_config(hidpp);
 		if (ret)
 			goto hid_hw_open_failed;
+	} else if (connected && (hidpp->quirks & HIDPP_QUIRK_CLASS_G920)) {
+		ret = g920_get_config(hidpp);
+		if (ret)
+			goto hid_hw_open_failed;
 	}
 
 	/* Block incoming packets */
@@ -1534,6 +1669,7 @@ static int hidpp_probe(struct hid_device *hdev, const struct hid_device_id *id)
 hid_hw_open_failed:
 	hid_device_io_stop(hdev);
 	if (hidpp->quirks & HIDPP_QUIRK_CLASS_G920) {
+		device_remove_file(&hdev->dev, &dev_attr_range);
 		hid_hw_close(hdev);
 		hid_hw_stop(hdev);
 	}
@@ -1550,8 +1686,10 @@ static void hidpp_remove(struct hid_device *hdev)
 {
 	struct hidpp_device *hidpp = hid_get_drvdata(hdev);
 
-	if (hidpp->quirks & HIDPP_QUIRK_CLASS_G920)
+	if (hidpp->quirks & HIDPP_QUIRK_CLASS_G920) {
+		device_remove_file(&hdev->dev, &dev_attr_range);
 		hid_hw_close(hdev);
+	}
 	hid_hw_stop(hdev);
 	cancel_work_sync(&hidpp->work);
 	mutex_destroy(&hidpp->send_mutex);
-- 
2.1.4