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>

4 files changed, 134 insertions, 0 deletions

diff --git a/drivers/hid/Kconfig b/drivers/hid/Kconfig
index 19c499f5623d..a18e06b81165 100644
--- a/drivers/hid/Kconfig
+++ b/drivers/hid/Kconfig
@@ -331,6 +331,12 @@ config HOLTEK_FF
           Say Y here if you have a Holtek On Line Grip based game controller
           and want to have force feedback support for it.
 
+config HID_GOOGLE_HAMMER
+        tristate "Google Hammer Keyboard"
+        depends on USB_HID && LEDS_CLASS
+        ---help---
+        Say Y here if you have a Google Hammer device.
+
 config HID_GT683R
         tristate "MSI GT68xR LED support"
         depends on LEDS_CLASS && USB_HID
diff --git a/drivers/hid/Makefile b/drivers/hid/Makefile
index eb13b9e92d85..4e9b57a44e96 100644
--- a/drivers/hid/Makefile
+++ b/drivers/hid/Makefile
@@ -44,6 +44,7 @@ obj-$(CONFIG_HID_ELO)		+= hid-elo.o
 obj-$(CONFIG_HID_EZKEY)         += hid-ezkey.o
 obj-$(CONFIG_HID_GEMBIRD)       += hid-gembird.o
 obj-$(CONFIG_HID_GFRM)          += hid-gfrm.o
+obj-$(CONFIG_HID_GOOGLE_HAMMER) += hid-google-hammer.o
 obj-$(CONFIG_HID_GT683R)        += hid-gt683r.o
 obj-$(CONFIG_HID_GYRATION)      += hid-gyration.o
 obj-$(CONFIG_HID_HOLTEK)        += hid-holtek-kbd.o
diff --git a/drivers/hid/hid-google-hammer.c b/drivers/hid/hid-google-hammer.c
new file mode 100644
index 000000000000..6486469ce0f6
--- /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");
diff --git a/drivers/hid/hid-ids.h b/drivers/hid/hid-ids.h
index 43ddcdfbd0da..360c2893bb2d 100644
--- a/drivers/hid/hid-ids.h
+++ b/drivers/hid/hid-ids.h
@@ -445,7 +445,10 @@
 #define USB_DEVICE_ID_GOODTOUCH_000f    0x000f
 
 #define USB_VENDOR_ID_GOOGLE            0x18d1
+#define USB_DEVICE_ID_GOOGLE_HAMMER     0x5022
 #define USB_DEVICE_ID_GOOGLE_TOUCH_ROSE 0x5028
+#define USB_DEVICE_ID_GOOGLE_STAFF      0x502b
+#define USB_DEVICE_ID_GOOGLE_WAND       0x502d
 
 #define USB_VENDOR_ID_GOTOP             0x08f2
 #define USB_DEVICE_ID_SUPER_Q2          0x007f