1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (c) 2020, NVIDIA CORPORATION. All rights reserved. 4 */ 5 6 #include <linux/acpi.h> 7 #include <linux/backlight.h> 8 #include <linux/mod_devicetable.h> 9 #include <linux/module.h> 10 #include <linux/platform_data/x86/nvidia-wmi-ec-backlight.h> 11 #include <linux/types.h> 12 #include <linux/wmi.h> 13 #include <acpi/video.h> 14 15 static bool force; 16 module_param(force, bool, 0444); 17 MODULE_PARM_DESC(force, "Force loading (disable acpi_backlight=xxx checks"); 18 19 /** 20 * wmi_brightness_notify() - helper function for calling WMI-wrapped ACPI method 21 * @w: Pointer to the struct wmi_device identified by %WMI_BRIGHTNESS_GUID 22 * @id: The WMI method ID to call (e.g. %WMI_BRIGHTNESS_METHOD_LEVEL or 23 * %WMI_BRIGHTNESS_METHOD_SOURCE) 24 * @mode: The operation to perform on the method (e.g. %WMI_BRIGHTNESS_MODE_SET 25 * or %WMI_BRIGHTNESS_MODE_GET) 26 * @val: Pointer to a value passed in by the caller when @mode is 27 * %WMI_BRIGHTNESS_MODE_SET, or a value passed out to caller when @mode 28 * is %WMI_BRIGHTNESS_MODE_GET or %WMI_BRIGHTNESS_MODE_GET_MAX_LEVEL. 29 * 30 * Returns 0 on success, or a negative error number on failure. 31 */ 32 static int wmi_brightness_notify(struct wmi_device *w, enum wmi_brightness_method id, enum wmi_brightness_mode mode, u32 *val) 33 { 34 struct wmi_brightness_args args = { 35 .mode = mode, 36 .val = 0, 37 .ret = 0, 38 }; 39 struct acpi_buffer buf = { (acpi_size)sizeof(args), &args }; 40 acpi_status status; 41 42 if (id < WMI_BRIGHTNESS_METHOD_LEVEL || 43 id >= WMI_BRIGHTNESS_METHOD_MAX || 44 mode < WMI_BRIGHTNESS_MODE_GET || mode >= WMI_BRIGHTNESS_MODE_MAX) 45 return -EINVAL; 46 47 if (mode == WMI_BRIGHTNESS_MODE_SET) 48 args.val = *val; 49 50 status = wmidev_evaluate_method(w, 0, id, &buf, &buf); 51 if (ACPI_FAILURE(status)) { 52 dev_err(&w->dev, "EC backlight control failed: %s\n", 53 acpi_format_exception(status)); 54 return -EIO; 55 } 56 57 if (mode != WMI_BRIGHTNESS_MODE_SET) 58 *val = args.ret; 59 60 return 0; 61 } 62 63 static int nvidia_wmi_ec_backlight_update_status(struct backlight_device *bd) 64 { 65 struct wmi_device *wdev = bl_get_data(bd); 66 67 return wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_LEVEL, 68 WMI_BRIGHTNESS_MODE_SET, 69 &bd->props.brightness); 70 } 71 72 static int nvidia_wmi_ec_backlight_get_brightness(struct backlight_device *bd) 73 { 74 struct wmi_device *wdev = bl_get_data(bd); 75 u32 level; 76 int ret; 77 78 ret = wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_LEVEL, 79 WMI_BRIGHTNESS_MODE_GET, &level); 80 if (ret < 0) 81 return ret; 82 83 return level; 84 } 85 86 static const struct backlight_ops nvidia_wmi_ec_backlight_ops = { 87 .update_status = nvidia_wmi_ec_backlight_update_status, 88 .get_brightness = nvidia_wmi_ec_backlight_get_brightness, 89 }; 90 91 static int nvidia_wmi_ec_backlight_probe(struct wmi_device *wdev, const void *ctx) 92 { 93 struct backlight_properties props = {}; 94 struct backlight_device *bdev; 95 int ret; 96 97 /* drivers/acpi/video_detect.c also checks that SOURCE == EC */ 98 if (!force && acpi_video_get_backlight_type() != acpi_backlight_nvidia_wmi_ec) 99 return -ENODEV; 100 101 /* 102 * Identify this backlight device as a firmware device so that it can 103 * be prioritized over any exposed GPU-driven raw device(s). 104 */ 105 props.type = BACKLIGHT_FIRMWARE; 106 107 ret = wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_LEVEL, 108 WMI_BRIGHTNESS_MODE_GET_MAX_LEVEL, 109 &props.max_brightness); 110 if (ret) 111 return ret; 112 113 ret = wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_LEVEL, 114 WMI_BRIGHTNESS_MODE_GET, &props.brightness); 115 if (ret) 116 return ret; 117 118 bdev = devm_backlight_device_register(&wdev->dev, 119 "nvidia_wmi_ec_backlight", 120 &wdev->dev, wdev, 121 &nvidia_wmi_ec_backlight_ops, 122 &props); 123 return PTR_ERR_OR_ZERO(bdev); 124 } 125 126 static const struct wmi_device_id nvidia_wmi_ec_backlight_id_table[] = { 127 { .guid_string = WMI_BRIGHTNESS_GUID }, 128 { } 129 }; 130 MODULE_DEVICE_TABLE(wmi, nvidia_wmi_ec_backlight_id_table); 131 132 static struct wmi_driver nvidia_wmi_ec_backlight_driver = { 133 .driver = { 134 .name = "nvidia-wmi-ec-backlight", 135 }, 136 .probe = nvidia_wmi_ec_backlight_probe, 137 .id_table = nvidia_wmi_ec_backlight_id_table, 138 }; 139 module_wmi_driver(nvidia_wmi_ec_backlight_driver); 140 141 MODULE_AUTHOR("Daniel Dadap <ddadap@nvidia.com>"); 142 MODULE_DESCRIPTION("NVIDIA WMI EC Backlight driver"); 143 MODULE_LICENSE("GPL"); 144