diff options
Diffstat (limited to 'drivers/platform/chrome/wilco_ec/keyboard_leds.c')
| -rw-r--r-- | drivers/platform/chrome/wilco_ec/keyboard_leds.c | 191 |
1 files changed, 191 insertions, 0 deletions
diff --git a/drivers/platform/chrome/wilco_ec/keyboard_leds.c b/drivers/platform/chrome/wilco_ec/keyboard_leds.c new file mode 100644 index 000000000000..bb0edf51dfda --- /dev/null +++ b/drivers/platform/chrome/wilco_ec/keyboard_leds.c @@ -0,0 +1,191 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Keyboard backlight LED driver for the Wilco Embedded Controller + * + * Copyright 2019 Google LLC + * + * Since the EC will never change the backlight level of its own accord, + * we don't need to implement a brightness_get() method. + */ + +#include <linux/device.h> +#include <linux/kernel.h> +#include <linux/leds.h> +#include <linux/platform_data/wilco-ec.h> +#include <linux/slab.h> + +#define WILCO_EC_COMMAND_KBBL 0x75 +#define WILCO_KBBL_MODE_FLAG_PWM BIT(1) /* Set brightness by percent. */ +#define WILCO_KBBL_DEFAULT_BRIGHTNESS 0 + +struct wilco_keyboard_leds { + struct wilco_ec_device *ec; + struct led_classdev keyboard; +}; + +enum wilco_kbbl_subcommand { + WILCO_KBBL_SUBCMD_GET_FEATURES = 0x00, + WILCO_KBBL_SUBCMD_GET_STATE = 0x01, + WILCO_KBBL_SUBCMD_SET_STATE = 0x02, +}; + +/** + * struct wilco_keyboard_leds_msg - Message to/from EC for keyboard LED control. + * @command: Always WILCO_EC_COMMAND_KBBL. + * @status: Set by EC to 0 on success, 0xFF on failure. + * @subcmd: One of enum wilco_kbbl_subcommand. + * @reserved3: Should be 0. + * @mode: Bit flags for used mode, we want to use WILCO_KBBL_MODE_FLAG_PWM. + * @reserved5to8: Should be 0. + * @percent: Brightness in 0-100. Only meaningful in PWM mode. + * @reserved10to15: Should be 0. + */ +struct wilco_keyboard_leds_msg { + u8 command; + u8 status; + u8 subcmd; + u8 reserved3; + u8 mode; + u8 reserved5to8[4]; + u8 percent; + u8 reserved10to15[6]; +} __packed; + +/* Send a request, get a response, and check that the response is good. */ +static int send_kbbl_msg(struct wilco_ec_device *ec, + struct wilco_keyboard_leds_msg *request, + struct wilco_keyboard_leds_msg *response) +{ + struct wilco_ec_message msg; + int ret; + + memset(&msg, 0, sizeof(msg)); + msg.type = WILCO_EC_MSG_LEGACY; + msg.request_data = request; + msg.request_size = sizeof(*request); + msg.response_data = response; + msg.response_size = sizeof(*response); + + ret = wilco_ec_mailbox(ec, &msg); + if (ret < 0) { + dev_err(ec->dev, + "Failed sending keyboard LEDs command: %d", ret); + return ret; + } + + if (response->status) { + dev_err(ec->dev, + "EC reported failure sending keyboard LEDs command: %d", + response->status); + return -EIO; + } + + return 0; +} + +static int set_kbbl(struct wilco_ec_device *ec, enum led_brightness brightness) +{ + struct wilco_keyboard_leds_msg request; + struct wilco_keyboard_leds_msg response; + + memset(&request, 0, sizeof(request)); + request.command = WILCO_EC_COMMAND_KBBL; + request.subcmd = WILCO_KBBL_SUBCMD_SET_STATE; + request.mode = WILCO_KBBL_MODE_FLAG_PWM; + request.percent = brightness; + + return send_kbbl_msg(ec, &request, &response); +} + +static int kbbl_exist(struct wilco_ec_device *ec, bool *exists) +{ + struct wilco_keyboard_leds_msg request; + struct wilco_keyboard_leds_msg response; + int ret; + + memset(&request, 0, sizeof(request)); + request.command = WILCO_EC_COMMAND_KBBL; + request.subcmd = WILCO_KBBL_SUBCMD_GET_FEATURES; + + ret = send_kbbl_msg(ec, &request, &response); + if (ret < 0) + return ret; + + *exists = response.status != 0xFF; + + return 0; +} + +/** + * kbbl_init() - Initialize the state of the keyboard backlight. + * @ec: EC device to talk to. + * + * Gets the current brightness, ensuring that the BIOS already initialized the + * backlight to PWM mode. If not in PWM mode, then the current brightness is + * meaningless, so set the brightness to WILCO_KBBL_DEFAULT_BRIGHTNESS. + * + * Return: Final brightness of the keyboard, or negative error code on failure. + */ +static int kbbl_init(struct wilco_ec_device *ec) +{ + struct wilco_keyboard_leds_msg request; + struct wilco_keyboard_leds_msg response; + int ret; + + memset(&request, 0, sizeof(request)); + request.command = WILCO_EC_COMMAND_KBBL; + request.subcmd = WILCO_KBBL_SUBCMD_GET_STATE; + + ret = send_kbbl_msg(ec, &request, &response); + if (ret < 0) + return ret; + + if (response.mode & WILCO_KBBL_MODE_FLAG_PWM) + return response.percent; + + ret = set_kbbl(ec, WILCO_KBBL_DEFAULT_BRIGHTNESS); + if (ret < 0) + return ret; + + return WILCO_KBBL_DEFAULT_BRIGHTNESS; +} + +static int wilco_keyboard_leds_set(struct led_classdev *cdev, + enum led_brightness brightness) +{ + struct wilco_keyboard_leds *wkl = + container_of(cdev, struct wilco_keyboard_leds, keyboard); + return set_kbbl(wkl->ec, brightness); +} + +int wilco_keyboard_leds_init(struct wilco_ec_device *ec) +{ + struct wilco_keyboard_leds *wkl; + bool leds_exist; + int ret; + + ret = kbbl_exist(ec, &leds_exist); + if (ret < 0) { + dev_err(ec->dev, + "Failed checking keyboard LEDs support: %d", ret); + return ret; + } + if (!leds_exist) + return 0; + + wkl = devm_kzalloc(ec->dev, sizeof(*wkl), GFP_KERNEL); + if (!wkl) + return -ENOMEM; + + wkl->ec = ec; + wkl->keyboard.name = "platform::kbd_backlight"; + wkl->keyboard.max_brightness = 100; + wkl->keyboard.flags = LED_CORE_SUSPENDRESUME; + wkl->keyboard.brightness_set_blocking = wilco_keyboard_leds_set; + ret = kbbl_init(ec); + if (ret < 0) + return ret; + wkl->keyboard.brightness = ret; + + return devm_led_classdev_register(ec->dev, &wkl->keyboard); +} |