diff options
Diffstat (limited to 'drivers/platform/x86/nvidia-wmi-ec-backlight.c')
| -rw-r--r-- | drivers/platform/x86/nvidia-wmi-ec-backlight.c | 213 |
1 files changed, 213 insertions, 0 deletions
diff --git a/drivers/platform/x86/nvidia-wmi-ec-backlight.c b/drivers/platform/x86/nvidia-wmi-ec-backlight.c new file mode 100644 index 000000000000..61e37194df70 --- /dev/null +++ b/drivers/platform/x86/nvidia-wmi-ec-backlight.c @@ -0,0 +1,213 @@ +// 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"); |