HID: google: add google hammer HID driver
Add Google hammer HID driver. This driver allow us to control hammer
keyboard backlight and support future features.
Signed-off-by: Wei-Ning Huang <wnhuang@google.com>
Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/drivers/hid/hid-google-hammer.c b/drivers/hid/hid-google-hammer.c
new file mode 100644
index 0000000..6486469
--- /dev/null
+++ b/drivers/hid/hid-google-hammer.c
@@ -0,0 +1,124 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * HID driver for Google Hammer device.
+ *
+ * Copyright (c) 2017 Google Inc.
+ * Author: Wei-Ning Huang <wnhuang@google.com>
+ */
+
+/*
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ */
+
+#include <linux/hid.h>
+#include <linux/leds.h>
+#include <linux/module.h>
+
+#include "hid-ids.h"
+
+#define MAX_BRIGHTNESS 100
+
+/* HID usage for keyboard backlight (Alphanumeric display brightness) */
+#define HID_AD_BRIGHTNESS 0x00140046
+
+struct hammer_kbd_leds {
+ struct led_classdev cdev;
+ struct hid_device *hdev;
+ u8 buf[2] ____cacheline_aligned;
+};
+
+static int hammer_kbd_brightness_set_blocking(struct led_classdev *cdev,
+ enum led_brightness br)
+{
+ struct hammer_kbd_leds *led = container_of(cdev,
+ struct hammer_kbd_leds,
+ cdev);
+ int ret;
+
+ led->buf[0] = 0;
+ led->buf[1] = br;
+
+ ret = hid_hw_output_report(led->hdev, led->buf, sizeof(led->buf));
+ if (ret == -ENOSYS)
+ ret = hid_hw_raw_request(led->hdev, 0, led->buf,
+ sizeof(led->buf),
+ HID_OUTPUT_REPORT,
+ HID_REQ_SET_REPORT);
+ if (ret < 0)
+ hid_err(led->hdev, "failed to set keyboard backlight: %d\n",
+ ret);
+ return ret;
+}
+
+static int hammer_register_leds(struct hid_device *hdev)
+{
+ struct hammer_kbd_leds *kbd_backlight;
+
+ kbd_backlight = devm_kzalloc(&hdev->dev,
+ sizeof(*kbd_backlight),
+ GFP_KERNEL);
+ if (!kbd_backlight)
+ return -ENOMEM;
+
+ kbd_backlight->hdev = hdev;
+ kbd_backlight->cdev.name = "hammer::kbd_backlight";
+ kbd_backlight->cdev.max_brightness = MAX_BRIGHTNESS;
+ kbd_backlight->cdev.brightness_set_blocking =
+ hammer_kbd_brightness_set_blocking;
+ kbd_backlight->cdev.flags = LED_HW_PLUGGABLE;
+
+ /* Set backlight to 0% initially. */
+ hammer_kbd_brightness_set_blocking(&kbd_backlight->cdev, 0);
+
+ return devm_led_classdev_register(&hdev->dev, &kbd_backlight->cdev);
+}
+
+static int hammer_input_configured(struct hid_device *hdev,
+ struct hid_input *hi)
+{
+ struct list_head *report_list =
+ &hdev->report_enum[HID_OUTPUT_REPORT].report_list;
+ struct hid_report *report;
+
+ if (list_empty(report_list))
+ return 0;
+
+ report = list_first_entry(report_list, struct hid_report, list);
+
+ if (report->maxfield == 1 &&
+ report->field[0]->application == HID_GD_KEYBOARD &&
+ report->field[0]->maxusage == 1 &&
+ report->field[0]->usage[0].hid == HID_AD_BRIGHTNESS) {
+ int err = hammer_register_leds(hdev);
+
+ if (err)
+ hid_warn(hdev,
+ "Failed to register keyboard backlight: %d\n",
+ err);
+ }
+
+ return 0;
+}
+
+static const struct hid_device_id hammer_devices[] = {
+ { HID_DEVICE(BUS_USB, HID_GROUP_GENERIC,
+ USB_VENDOR_ID_GOOGLE, USB_DEVICE_ID_GOOGLE_HAMMER) },
+ { HID_DEVICE(BUS_USB, HID_GROUP_GENERIC,
+ USB_VENDOR_ID_GOOGLE, USB_DEVICE_ID_GOOGLE_STAFF) },
+ { HID_DEVICE(BUS_USB, HID_GROUP_GENERIC,
+ USB_VENDOR_ID_GOOGLE, USB_DEVICE_ID_GOOGLE_WAND) },
+ { }
+};
+MODULE_DEVICE_TABLE(hid, hammer_devices);
+
+static struct hid_driver hammer_driver = {
+ .name = "hammer",
+ .id_table = hammer_devices,
+ .input_configured = hammer_input_configured,
+};
+module_hid_driver(hammer_driver);
+
+MODULE_LICENSE("GPL");