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 14 /** 15 * wmi_brightness_notify() - helper function for calling WMI-wrapped ACPI method 16 * @w: Pointer to the struct wmi_device identified by %WMI_BRIGHTNESS_GUID 17 * @id: The WMI method ID to call (e.g. %WMI_BRIGHTNESS_METHOD_LEVEL or 18 * %WMI_BRIGHTNESS_METHOD_SOURCE) 19 * @mode: The operation to perform on the method (e.g. %WMI_BRIGHTNESS_MODE_SET 20 * or %WMI_BRIGHTNESS_MODE_GET) 21 * @val: Pointer to a value passed in by the caller when @mode is 22 * %WMI_BRIGHTNESS_MODE_SET, or a value passed out to caller when @mode 23 * is %WMI_BRIGHTNESS_MODE_GET or %WMI_BRIGHTNESS_MODE_GET_MAX_LEVEL. 24 * 25 * Returns 0 on success, or a negative error number on failure. 26 */ 27 static int wmi_brightness_notify(struct wmi_device *w, enum wmi_brightness_method id, enum wmi_brightness_mode mode, u32 *val) 28 { 29 struct wmi_brightness_args args = { 30 .mode = mode, 31 .val = 0, 32 .ret = 0, 33 }; 34 struct acpi_buffer buf = { (acpi_size)sizeof(args), &args }; 35 acpi_status status; 36 37 if (id < WMI_BRIGHTNESS_METHOD_LEVEL || 38 id >= WMI_BRIGHTNESS_METHOD_MAX || 39 mode < WMI_BRIGHTNESS_MODE_GET || mode >= WMI_BRIGHTNESS_MODE_MAX) 40 return -EINVAL; 41 42 if (mode == WMI_BRIGHTNESS_MODE_SET) 43 args.val = *val; 44 45 status = wmidev_evaluate_method(w, 0, id, &buf, &buf); 46 if (ACPI_FAILURE(status)) { 47 dev_err(&w->dev, "EC backlight control failed: %s\n", 48 acpi_format_exception(status)); 49 return -EIO; 50 } 51 52 if (mode != WMI_BRIGHTNESS_MODE_SET) 53 *val = args.ret; 54 55 return 0; 56 } 57 58 static int nvidia_wmi_ec_backlight_update_status(struct backlight_device *bd) 59 { 60 struct wmi_device *wdev = bl_get_data(bd); 61 62 return wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_LEVEL, 63 WMI_BRIGHTNESS_MODE_SET, 64 &bd->props.brightness); 65 } 66 67 static int nvidia_wmi_ec_backlight_get_brightness(struct backlight_device *bd) 68 { 69 struct wmi_device *wdev = bl_get_data(bd); 70 u32 level; 71 int ret; 72 73 ret = wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_LEVEL, 74 WMI_BRIGHTNESS_MODE_GET, &level); 75 if (ret < 0) 76 return ret; 77 78 return level; 79 } 80 81 static const struct backlight_ops nvidia_wmi_ec_backlight_ops = { 82 .update_status = nvidia_wmi_ec_backlight_update_status, 83 .get_brightness = nvidia_wmi_ec_backlight_get_brightness, 84 }; 85 86 static int nvidia_wmi_ec_backlight_probe(struct wmi_device *wdev, const void *ctx) 87 { 88 struct backlight_properties props = {}; 89 struct backlight_device *bdev; 90 u32 source; 91 int ret; 92 93 ret = wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_SOURCE, 94 WMI_BRIGHTNESS_MODE_GET, &source); 95 if (ret) 96 return ret; 97 98 /* 99 * This driver is only to be used when brightness control is handled 100 * by the EC; otherwise, the GPU driver(s) should control brightness. 101 */ 102 if (source != WMI_BRIGHTNESS_SOURCE_EC) 103 return -ENODEV; 104 105 /* 106 * Identify this backlight device as a firmware device so that it can 107 * be prioritized over any exposed GPU-driven raw device(s). 108 */ 109 props.type = BACKLIGHT_FIRMWARE; 110 111 ret = wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_LEVEL, 112 WMI_BRIGHTNESS_MODE_GET_MAX_LEVEL, 113 &props.max_brightness); 114 if (ret) 115 return ret; 116 117 ret = wmi_brightness_notify(wdev, WMI_BRIGHTNESS_METHOD_LEVEL, 118 WMI_BRIGHTNESS_MODE_GET, &props.brightness); 119 if (ret) 120 return ret; 121 122 bdev = devm_backlight_device_register(&wdev->dev, 123 "nvidia_wmi_ec_backlight", 124 &wdev->dev, wdev, 125 &nvidia_wmi_ec_backlight_ops, 126 &props); 127 return PTR_ERR_OR_ZERO(bdev); 128 } 129 130 static const struct wmi_device_id nvidia_wmi_ec_backlight_id_table[] = { 131 { .guid_string = WMI_BRIGHTNESS_GUID }, 132 { } 133 }; 134 MODULE_DEVICE_TABLE(wmi, nvidia_wmi_ec_backlight_id_table); 135 136 static struct wmi_driver nvidia_wmi_ec_backlight_driver = { 137 .driver = { 138 .name = "nvidia-wmi-ec-backlight", 139 }, 140 .probe = nvidia_wmi_ec_backlight_probe, 141 .id_table = nvidia_wmi_ec_backlight_id_table, 142 }; 143 module_wmi_driver(nvidia_wmi_ec_backlight_driver); 144 145 MODULE_AUTHOR("Daniel Dadap <ddadap@nvidia.com>"); 146 MODULE_DESCRIPTION("NVIDIA WMI EC Backlight driver"); 147 MODULE_LICENSE("GPL"); 148