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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 wmaa_method - WMI method IDs for ACPI WMAA
* @WMAA_METHOD_LEVEL: Get or set the brightness level,
* or get the maximum brightness level.
* @WMAA_METHOD_SOURCE: Get the source for backlight control.
*/
enum wmaa_method {
WMAA_METHOD_LEVEL = 1,
WMAA_METHOD_SOURCE = 2,
WMAA_METHOD_MAX
};
/**
* enum wmaa_mode - Operation mode for ACPI WMAA method
* @WMAA_MODE_GET: Get the current brightness level or source.
* @WMAA_MODE_SET: Set the brightness level.
* @WMAA_MODE_GET_MAX_LEVEL: Get the maximum brightness level. This is only
* valid when the WMI method is %WMAA_METHOD_LEVEL.
*/
enum wmaa_mode {
WMAA_MODE_GET = 0,
WMAA_MODE_SET = 1,
WMAA_MODE_GET_MAX_LEVEL = 2,
WMAA_MODE_MAX
};
/**
* enum wmaa_source - Backlight brightness control source identification
* @WMAA_SOURCE_GPU: Backlight brightness is controlled by the GPU.
* @WMAA_SOURCE_EC: Backlight brightness is controlled by the system's
* Embedded Controller (EC).
* @WMAA_SOURCE_AUX: Backlight brightness is controlled over the DisplayPort
* AUX channel.
*/
enum wmaa_source {
WMAA_SOURCE_GPU = 1,
WMAA_SOURCE_EC = 2,
WMAA_SOURCE_AUX = 3,
WMAA_SOURCE_MAX
};
/**
* struct wmaa_args - arguments for the ACPI WMAA method
* @mode: Pass in an &enum wmaa_mode value to select between getting or
* setting a value.
* @val: In parameter for value to set when operating in %WMAA_MODE_SET
* mode. Not used in %WMAA_MODE_GET or %WMAA_MODE_GET_MAX_LEVEL mode.
* @ret: Out parameter returning retrieved value when operating in
* %WMAA_MODE_GET or %WMAA_MODE_GET_MAX_LEVEL mode. Not used in
* %WMAA_MODE_SET mode.
* @ignored: Padding; not used. The ACPI method expects a 24 byte params struct.
*
* This is the parameters structure for the ACPI WMAA 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 %WMAA_METHOD_LEVEL, or an &enum wmaa_source value
* when the WMI method ID is %WMAA_METHOD_SOURCE.
*/
struct wmaa_args {
u32 mode;
u32 val;
u32 ret;
u32 ignored[3];
};
/**
* wmi_call_wmaa() - helper function for calling ACPI WMAA via its WMI wrapper
* @w: Pointer to the struct wmi_device identified by %WMAA_WMI_GUID
* @id: The method ID for the ACPI WMAA method (e.g. %WMAA_METHOD_LEVEL or
* %WMAA_METHOD_SOURCE)
* @mode: The operation to perform on the ACPI WMAA method (e.g. %WMAA_MODE_SET
* or %WMAA_MODE_GET)
* @val: Pointer to a value passed in by the caller when @mode is
* %WMAA_MODE_SET, or a value passed out to the caller when @mode is
* %WMAA_MODE_GET or %WMAA_MODE_GET_MAX_LEVEL.
*
* Returns 0 on success, or a negative error number on failure.
*/
static int wmi_call_wmaa(struct wmi_device *w, enum wmaa_method id, enum wmaa_mode mode, u32 *val)
{
struct wmaa_args args = {
.mode = mode,
.val = 0,
.ret = 0,
};
struct acpi_buffer buf = { (acpi_size)sizeof(args), &args };
acpi_status status;
if (id < WMAA_METHOD_LEVEL || id >= WMAA_METHOD_MAX ||
mode < WMAA_MODE_GET || mode >= WMAA_MODE_MAX)
return -EINVAL;
if (mode == WMAA_MODE_SET)
args.val = *val;
status = wmidev_evaluate_method(w, 0, id, &buf, &buf);
if (ACPI_FAILURE(status)) {
dev_err(&w->dev, "ACPI WMAA failed: %s\n",
acpi_format_exception(status));
return -EIO;
}
if (mode != WMAA_MODE_SET)
*val = args.ret;
return 0;
}
static int wmaa_backlight_update_status(struct backlight_device *bd)
{
struct wmi_device *wdev = bl_get_data(bd);
return wmi_call_wmaa(wdev, WMAA_METHOD_LEVEL, WMAA_MODE_SET,
&bd->props.brightness);
}
static int wmaa_backlight_get_brightness(struct backlight_device *bd)
{
struct wmi_device *wdev = bl_get_data(bd);
u32 level;
int ret;
ret = wmi_call_wmaa(wdev, WMAA_METHOD_LEVEL, WMAA_MODE_GET, &level);
if (ret < 0)
return ret;
return level;
}
static const struct backlight_ops wmaa_backlight_ops = {
.update_status = wmaa_backlight_update_status,
.get_brightness = wmaa_backlight_get_brightness,
};
static int wmaa_backlight_wmi_probe(struct wmi_device *wdev, const void *ctx)
{
struct backlight_properties props = {};
struct backlight_device *bdev;
u32 source;
int ret;
ret = wmi_call_wmaa(wdev, WMAA_METHOD_SOURCE, WMAA_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 != WMAA_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_call_wmaa(wdev, WMAA_METHOD_LEVEL, WMAA_MODE_GET_MAX_LEVEL,
&props.max_brightness);
if (ret)
return ret;
ret = wmi_call_wmaa(wdev, WMAA_METHOD_LEVEL, WMAA_MODE_GET,
&props.brightness);
if (ret)
return ret;
bdev = devm_backlight_device_register(&wdev->dev, "wmaa_backlight",
&wdev->dev, wdev,
&wmaa_backlight_ops, &props);
return PTR_ERR_OR_ZERO(bdev);
}
#define WMAA_WMI_GUID "603E9613-EF25-4338-A3D0-C46177516DB7"
static const struct wmi_device_id wmaa_backlight_wmi_id_table[] = {
{ .guid_string = WMAA_WMI_GUID },
{ }
};
MODULE_DEVICE_TABLE(wmi, wmaa_backlight_wmi_id_table);
static struct wmi_driver wmaa_backlight_wmi_driver = {
.driver = {
.name = "wmaa-backlight",
},
.probe = wmaa_backlight_wmi_probe,
.id_table = wmaa_backlight_wmi_id_table,
};
module_wmi_driver(wmaa_backlight_wmi_driver);
MODULE_AUTHOR("Daniel Dadap <ddadap@nvidia.com>");
MODULE_DESCRIPTION("WMAA Backlight WMI driver");
MODULE_LICENSE("GPL");
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