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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (c) 2020, NVIDIA CORPORATION. All rights reserved.
*/
#include <linux/acpi.h>
#include <linux/backlight.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/wmi.h>
/**
* enum wmi_brightness_method - WMI method IDs
* @WMI_BRIGHTNESS_METHOD_LEVEL: Get/Set EC brightness level status
* @WMI_BRIGHTNESS_METHOD_SOURCE: Get/Set EC Brightness Source
*/
enum wmi_brightness_method {
WMI_BRIGHTNESS_METHOD_LEVEL = 1,
WMI_BRIGHTNESS_METHOD_SOURCE = 2,
WMI_BRIGHTNESS_METHOD_MAX
};
/**
* enum wmi_brightness_mode - Operation mode for WMI-wrapped method
* @WMI_BRIGHTNESS_MODE_GET: Get the current brightness level/source.
* @WMI_BRIGHTNESS_MODE_SET: Set the brightness level.
* @WMI_BRIGHTNESS_MODE_GET_MAX_LEVEL: Get the maximum brightness level. This
* is only valid when the WMI method is
* %WMI_BRIGHTNESS_METHOD_LEVEL.
*/
enum wmi_brightness_mode {
WMI_BRIGHTNESS_MODE_GET = 0,
WMI_BRIGHTNESS_MODE_SET = 1,
WMI_BRIGHTNESS_MODE_GET_MAX_LEVEL = 2,
WMI_BRIGHTNESS_MODE_MAX
};
/**
* enum wmi_brightness_source - Backlight brightness control source selection
* @WMI_BRIGHTNESS_SOURCE_GPU: Backlight brightness is controlled by the GPU.
* @WMI_BRIGHTNESS_SOURCE_EC: Backlight brightness is controlled by the
* system's Embedded Controller (EC).
* @WMI_BRIGHTNESS_SOURCE_AUX: Backlight brightness is controlled over the
* DisplayPort AUX channel.
*/
enum wmi_brightness_source {
WMI_BRIGHTNESS_SOURCE_GPU = 1,
WMI_BRIGHTNESS_SOURCE_EC = 2,
WMI_BRIGHTNESS_SOURCE_AUX = 3,
WMI_BRIGHTNESS_SOURCE_MAX
};
/**
* struct wmi_brightness_args - arguments for the WMI-wrapped ACPI method
* @mode: Pass in an &enum wmi_brightness_mode value to select between
* getting or setting a value.
* @val: In parameter for value to set when using %WMI_BRIGHTNESS_MODE_SET
* mode. Not used in conjunction with %WMI_BRIGHTNESS_MODE_GET or
* %WMI_BRIGHTNESS_MODE_GET_MAX_LEVEL mode.
* @ret: Out parameter returning retrieved value when operating in
* %WMI_BRIGHTNESS_MODE_GET or %WMI_BRIGHTNESS_MODE_GET_MAX_LEVEL
* mode. Not used in %WMI_BRIGHTNESS_MODE_SET mode.
* @ignored: Padding; not used. The ACPI method expects a 24 byte params struct.
*
* This is the parameters structure for the WmiBrightnessNotify ACPI method as
* wrapped by WMI. The value passed in to @val or returned by @ret will be a
* brightness value when the WMI method ID is %WMI_BRIGHTNESS_METHOD_LEVEL, or
* an &enum wmi_brightness_source value with %WMI_BRIGHTNESS_METHOD_SOURCE.
*/
struct wmi_brightness_args {
u32 mode;
u32 val;
u32 ret;
u32 ignored[3];
};
/**
* wmi_brightness_notify() - helper function for calling WMI-wrapped ACPI method
* @w: Pointer to the struct wmi_device identified by %WMI_BRIGHTNESS_GUID
* @id: The WMI method ID to call (e.g. %WMI_BRIGHTNESS_METHOD_LEVEL or
* %WMI_BRIGHTNESS_METHOD_SOURCE)
* @mode: The operation to perform on the method (e.g. %WMI_BRIGHTNESS_MODE_SET
* or %WMI_BRIGHTNESS_MODE_GET)
* @val: Pointer to a value passed in by the caller when @mode is
* %WMI_BRIGHTNESS_MODE_SET, or a value passed out to caller when @mode
* is %WMI_BRIGHTNESS_MODE_GET or %WMI_BRIGHTNESS_MODE_GET_MAX_LEVEL.
*
* Returns 0 on success, or a negative error number on failure.
*/
static int wmi_brightness_notify(struct wmi_device *w, enum wmi_brightness_method id, enum wmi_brightness_mode mode, u32 *val)
{
struct wmi_brightness_args args = {
.mode = mode,
.val = 0,
.ret = 0,
};
struct acpi_buffer buf = { (acpi_size)sizeof(args), &args };
acpi_status status;
if (id < WMI_BRIGHTNESS_METHOD_LEVEL ||
id >= WMI_BRIGHTNESS_METHOD_MAX ||
mode < WMI_BRIGHTNESS_MODE_GET || mode >= WMI_BRIGHTNESS_MODE_MAX)
return -EINVAL;
if (mode == WMI_BRIGHTNESS_MODE_SET)
args.val = *val;
status = wmidev_evaluate_method(w, 0, id, &buf, &buf);
if (ACPI_FAILURE(status)) {
dev_err(&w->dev, "EC backlight control failed: %s\n",
acpi_format_exception(status));
return -EIO;
}
if (mode != WMI_BRIGHTNESS_MODE_SET)
*val = args.ret;
return 0;
}
static int nvidia_wmi_ec_backlight_update_status(struct backlight_device *bd)
{
struct wmi_device *wdev = bl_get_data(bd);
return wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_LEVEL,
WMI_BRIGHTNESS_MODE_SET,
&bd->props.brightness);
}
static int nvidia_wmi_ec_backlight_get_brightness(struct backlight_device *bd)
{
struct wmi_device *wdev = bl_get_data(bd);
u32 level;
int ret;
ret = wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_LEVEL,
WMI_BRIGHTNESS_MODE_GET, &level);
if (ret < 0)
return ret;
return level;
}
static const struct backlight_ops nvidia_wmi_ec_backlight_ops = {
.update_status = nvidia_wmi_ec_backlight_update_status,
.get_brightness = nvidia_wmi_ec_backlight_get_brightness,
};
static int nvidia_wmi_ec_backlight_probe(struct wmi_device *wdev, const void *ctx)
{
struct backlight_properties props = {};
struct backlight_device *bdev;
u32 source;
int ret;
ret = wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_SOURCE,
WMI_BRIGHTNESS_MODE_GET, &source);
if (ret)
return ret;
/*
* This driver is only to be used when brightness control is handled
* by the EC; otherwise, the GPU driver(s) should control brightness.
*/
if (source != WMI_BRIGHTNESS_SOURCE_EC)
return -ENODEV;
/*
* Identify this backlight device as a firmware device so that it can
* be prioritized over any exposed GPU-driven raw device(s).
*/
props.type = BACKLIGHT_FIRMWARE;
ret = wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_LEVEL,
WMI_BRIGHTNESS_MODE_GET_MAX_LEVEL,
&props.max_brightness);
if (ret)
return ret;
ret = wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_LEVEL,
WMI_BRIGHTNESS_MODE_GET, &props.brightness);
if (ret)
return ret;
bdev = devm_backlight_device_register(&wdev->dev,
"nvidia_wmi_ec_backlight",
&wdev->dev, wdev,
&nvidia_wmi_ec_backlight_ops,
&props);
return PTR_ERR_OR_ZERO(bdev);
}
#define WMI_BRIGHTNESS_GUID "603E9613-EF25-4338-A3D0-C46177516DB7"
static const struct wmi_device_id nvidia_wmi_ec_backlight_id_table[] = {
{ .guid_string = WMI_BRIGHTNESS_GUID },
{ }
};
MODULE_DEVICE_TABLE(wmi, nvidia_wmi_ec_backlight_id_table);
static struct wmi_driver nvidia_wmi_ec_backlight_driver = {
.driver = {
.name = "nvidia-wmi-ec-backlight",
},
.probe = nvidia_wmi_ec_backlight_probe,
.id_table = nvidia_wmi_ec_backlight_id_table,
};
module_wmi_driver(nvidia_wmi_ec_backlight_driver);
MODULE_AUTHOR("Daniel Dadap <ddadap@nvidia.com>");
MODULE_DESCRIPTION("NVIDIA WMI EC Backlight driver");
MODULE_LICENSE("GPL");
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