// 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);
}
