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1// SPDX-License-Identifier: GPL-2.02/*3 * Keyboard backlight LED driver for the Wilco Embedded Controller4 *5 * Copyright 2019 Google LLC6 *7 * Since the EC will never change the backlight level of its own accord,8 * we don't need to implement a brightness_get() method.9 */10 11#include <linux/device.h>12#include <linux/kernel.h>13#include <linux/leds.h>14#include <linux/platform_data/wilco-ec.h>15#include <linux/slab.h>16 17#define WILCO_EC_COMMAND_KBBL 0x7518#define WILCO_KBBL_MODE_FLAG_PWM BIT(1) /* Set brightness by percent. */19#define WILCO_KBBL_DEFAULT_BRIGHTNESS 020 21struct wilco_keyboard_leds {22 struct wilco_ec_device *ec;23 struct led_classdev keyboard;24};25 26enum wilco_kbbl_subcommand {27 WILCO_KBBL_SUBCMD_GET_FEATURES = 0x00,28 WILCO_KBBL_SUBCMD_GET_STATE = 0x01,29 WILCO_KBBL_SUBCMD_SET_STATE = 0x02,30};31 32/**33 * struct wilco_keyboard_leds_msg - Message to/from EC for keyboard LED control.34 * @command: Always WILCO_EC_COMMAND_KBBL.35 * @status: Set by EC to 0 on success, 0xFF on failure.36 * @subcmd: One of enum wilco_kbbl_subcommand.37 * @reserved3: Should be 0.38 * @mode: Bit flags for used mode, we want to use WILCO_KBBL_MODE_FLAG_PWM.39 * @reserved5to8: Should be 0.40 * @percent: Brightness in 0-100. Only meaningful in PWM mode.41 * @reserved10to15: Should be 0.42 */43struct wilco_keyboard_leds_msg {44 u8 command;45 u8 status;46 u8 subcmd;47 u8 reserved3;48 u8 mode;49 u8 reserved5to8[4];50 u8 percent;51 u8 reserved10to15[6];52} __packed;53 54/* Send a request, get a response, and check that the response is good. */55static int send_kbbl_msg(struct wilco_ec_device *ec,56 struct wilco_keyboard_leds_msg *request,57 struct wilco_keyboard_leds_msg *response)58{59 struct wilco_ec_message msg;60 int ret;61 62 memset(&msg, 0, sizeof(msg));63 msg.type = WILCO_EC_MSG_LEGACY;64 msg.request_data = request;65 msg.request_size = sizeof(*request);66 msg.response_data = response;67 msg.response_size = sizeof(*response);68 69 ret = wilco_ec_mailbox(ec, &msg);70 if (ret < 0) {71 dev_err(ec->dev,72 "Failed sending keyboard LEDs command: %d\n", ret);73 return ret;74 }75 76 return 0;77}78 79static int set_kbbl(struct wilco_ec_device *ec, enum led_brightness brightness)80{81 struct wilco_keyboard_leds_msg request;82 struct wilco_keyboard_leds_msg response;83 int ret;84 85 memset(&request, 0, sizeof(request));86 request.command = WILCO_EC_COMMAND_KBBL;87 request.subcmd = WILCO_KBBL_SUBCMD_SET_STATE;88 request.mode = WILCO_KBBL_MODE_FLAG_PWM;89 request.percent = brightness;90 91 ret = send_kbbl_msg(ec, &request, &response);92 if (ret < 0)93 return ret;94 95 if (response.status) {96 dev_err(ec->dev,97 "EC reported failure sending keyboard LEDs command: %d\n",98 response.status);99 return -EIO;100 }101 102 return 0;103}104 105static int kbbl_exist(struct wilco_ec_device *ec, bool *exists)106{107 struct wilco_keyboard_leds_msg request;108 struct wilco_keyboard_leds_msg response;109 int ret;110 111 memset(&request, 0, sizeof(request));112 request.command = WILCO_EC_COMMAND_KBBL;113 request.subcmd = WILCO_KBBL_SUBCMD_GET_FEATURES;114 115 ret = send_kbbl_msg(ec, &request, &response);116 if (ret < 0)117 return ret;118 119 *exists = response.status != 0xFF;120 121 return 0;122}123 124/**125 * kbbl_init() - Initialize the state of the keyboard backlight.126 * @ec: EC device to talk to.127 *128 * Gets the current brightness, ensuring that the BIOS already initialized the129 * backlight to PWM mode. If not in PWM mode, then the current brightness is130 * meaningless, so set the brightness to WILCO_KBBL_DEFAULT_BRIGHTNESS.131 *132 * Return: Final brightness of the keyboard, or negative error code on failure.133 */134static int kbbl_init(struct wilco_ec_device *ec)135{136 struct wilco_keyboard_leds_msg request;137 struct wilco_keyboard_leds_msg response;138 int ret;139 140 memset(&request, 0, sizeof(request));141 request.command = WILCO_EC_COMMAND_KBBL;142 request.subcmd = WILCO_KBBL_SUBCMD_GET_STATE;143 144 ret = send_kbbl_msg(ec, &request, &response);145 if (ret < 0)146 return ret;147 148 if (response.status) {149 dev_err(ec->dev,150 "EC reported failure sending keyboard LEDs command: %d\n",151 response.status);152 return -EIO;153 }154 155 if (response.mode & WILCO_KBBL_MODE_FLAG_PWM)156 return response.percent;157 158 ret = set_kbbl(ec, WILCO_KBBL_DEFAULT_BRIGHTNESS);159 if (ret < 0)160 return ret;161 162 return WILCO_KBBL_DEFAULT_BRIGHTNESS;163}164 165static int wilco_keyboard_leds_set(struct led_classdev *cdev,166 enum led_brightness brightness)167{168 struct wilco_keyboard_leds *wkl =169 container_of(cdev, struct wilco_keyboard_leds, keyboard);170 return set_kbbl(wkl->ec, brightness);171}172 173int wilco_keyboard_leds_init(struct wilco_ec_device *ec)174{175 struct wilco_keyboard_leds *wkl;176 bool leds_exist;177 int ret;178 179 ret = kbbl_exist(ec, &leds_exist);180 if (ret < 0) {181 dev_err(ec->dev,182 "Failed checking keyboard LEDs support: %d\n", ret);183 return ret;184 }185 if (!leds_exist)186 return 0;187 188 wkl = devm_kzalloc(ec->dev, sizeof(*wkl), GFP_KERNEL);189 if (!wkl)190 return -ENOMEM;191 192 wkl->ec = ec;193 wkl->keyboard.name = "platform::kbd_backlight";194 wkl->keyboard.max_brightness = 100;195 wkl->keyboard.flags = LED_CORE_SUSPENDRESUME;196 wkl->keyboard.brightness_set_blocking = wilco_keyboard_leds_set;197 ret = kbbl_init(ec);198 if (ret < 0)199 return ret;200 wkl->keyboard.brightness = ret;201 202 return devm_led_classdev_register(ec->dev, &wkl->keyboard);203}204