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authorSimon Que <sque@chromium.org>2016-03-08 11:12:46 -0800
committerOlof Johansson <olof@lixom.net>2016-05-11 11:55:47 -0700
commit492ef7829d2d09428803bffb187d5781bbc12ca5 (patch)
treed6f242596a5864505e3664d0f1a5e6861e0cff2f /drivers/platform/chrome/cros_kbd_led_backlight.c
parent48b9b6d4699e23cda45756b6a1fe5d481ba45914 (diff)
platform/chrome: Add Chrome OS keyboard backlight LEDs support
This is a driver for ACPI-based keyboard backlight LEDs found on Chromebooks. The driver locates \\_SB.KBLT ACPI device and exports backlight as "chromeos::kbd_backlight" LED class device in sysfs. Signed-off-by: Simon Que <sque@chromium.org> Signed-off-by: Duncan Laurie <dlaurie@chromium.org> Tested-by: Evan McClain <aeroevan@gmail.com> Signed-off-by: Dmitry Torokhov <dtor@chromium.org> Signed-off-by: Olof Johansson <olof@lixom.net>
Diffstat (limited to 'drivers/platform/chrome/cros_kbd_led_backlight.c')
-rw-r--r--drivers/platform/chrome/cros_kbd_led_backlight.c122
1 files changed, 122 insertions, 0 deletions
diff --git a/drivers/platform/chrome/cros_kbd_led_backlight.c b/drivers/platform/chrome/cros_kbd_led_backlight.c
new file mode 100644
index 000000000000..ca3e4da852b4
--- /dev/null
+++ b/drivers/platform/chrome/cros_kbd_led_backlight.c
@@ -0,0 +1,122 @@
+/*
+ * Keyboard backlight LED driver for Chrome OS.
+ *
+ * Copyright (C) 2012 Google, Inc.
+ *
+ * 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.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/acpi.h>
+#include <linux/leds.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+
+/* Keyboard LED ACPI Device must be defined in firmware */
+#define ACPI_KEYBOARD_BACKLIGHT_DEVICE "\\_SB.KBLT"
+#define ACPI_KEYBOARD_BACKLIGHT_READ ACPI_KEYBOARD_BACKLIGHT_DEVICE ".KBQC"
+#define ACPI_KEYBOARD_BACKLIGHT_WRITE ACPI_KEYBOARD_BACKLIGHT_DEVICE ".KBCM"
+
+#define ACPI_KEYBOARD_BACKLIGHT_MAX 100
+
+static void keyboard_led_set_brightness(struct led_classdev *cdev,
+ enum led_brightness brightness)
+{
+ union acpi_object param;
+ struct acpi_object_list input;
+ acpi_status status;
+
+ param.type = ACPI_TYPE_INTEGER;
+ param.integer.value = brightness;
+ input.count = 1;
+ input.pointer = &param;
+
+ status = acpi_evaluate_object(NULL, ACPI_KEYBOARD_BACKLIGHT_WRITE,
+ &input, NULL);
+ if (ACPI_FAILURE(status))
+ dev_err(cdev->dev, "Error setting keyboard LED value: %d\n",
+ status);
+}
+
+static enum led_brightness
+keyboard_led_get_brightness(struct led_classdev *cdev)
+{
+ unsigned long long brightness;
+ acpi_status status;
+
+ status = acpi_evaluate_integer(NULL, ACPI_KEYBOARD_BACKLIGHT_READ,
+ NULL, &brightness);
+ if (ACPI_FAILURE(status)) {
+ dev_err(cdev->dev, "Error getting keyboard LED value: %d\n",
+ status);
+ return -EIO;
+ }
+
+ return brightness;
+}
+
+static int keyboard_led_probe(struct platform_device *pdev)
+{
+ struct led_classdev *cdev;
+ acpi_handle handle;
+ acpi_status status;
+ int error;
+
+ /* Look for the keyboard LED ACPI Device */
+ status = acpi_get_handle(ACPI_ROOT_OBJECT,
+ ACPI_KEYBOARD_BACKLIGHT_DEVICE,
+ &handle);
+ if (ACPI_FAILURE(status)) {
+ dev_err(&pdev->dev, "Unable to find ACPI device %s: %d\n",
+ ACPI_KEYBOARD_BACKLIGHT_DEVICE, status);
+ return -ENXIO;
+ }
+
+ cdev = devm_kzalloc(&pdev->dev, sizeof(*cdev), GFP_KERNEL);
+ if (!cdev)
+ return -ENOMEM;
+
+ cdev->name = "chromeos::kbd_backlight";
+ cdev->max_brightness = ACPI_KEYBOARD_BACKLIGHT_MAX;
+ cdev->flags |= LED_CORE_SUSPENDRESUME;
+ cdev->brightness_set = keyboard_led_set_brightness;
+ cdev->brightness_get = keyboard_led_get_brightness;
+
+ error = devm_led_classdev_register(&pdev->dev, cdev);
+ if (error)
+ return error;
+
+ return 0;
+}
+
+static const struct acpi_device_id keyboard_led_id[] = {
+ { "GOOG0002", 0 },
+ { }
+};
+MODULE_DEVICE_TABLE(acpi, keyboard_led_id);
+
+static struct platform_driver keyboard_led_driver = {
+ .driver = {
+ .name = "chromeos-keyboard-leds",
+ .acpi_match_table = ACPI_PTR(keyboard_led_id),
+ },
+ .probe = keyboard_led_probe,
+};
+module_platform_driver(keyboard_led_driver);
+
+MODULE_AUTHOR("Simon Que <sque@chromium.org>");
+MODULE_DESCRIPTION("ChromeOS Keyboard backlight LED Driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:chromeos-keyboard-leds");