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platform/chrome: wilco_ec: Add keyboard backlight LED support

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The EC is in charge of controlling the keyboard backlight on
the Wilco platform. We expose a standard LED class device
named platform::kbd_backlight.

Since the EC will never change the backlight level of its own accord,
we don't need to implement a brightness_get() method.

Signed-off-by: Nick Crews <ncrews@chromium.org>
Signed-off-by: Daniel Campello <campello@chromium.org>
Reviewed-by: Daniel Campello <campello@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
This commit is contained in:
Daniel Campello 2019-11-06 09:33:19 -07:00 committed by Enric Balletbo i Serra
parent 3c4d77b689
commit 119a3cb6d6
5 changed files with 216 additions and 6 deletions
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2
drivers/platform/chrome/wilco_ec/Kconfig
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@ -1,7 +1,7 @@
# SPDX-License-Identifier: GPL-2.0-only
config WILCO_EC
tristate "ChromeOS Wilco Embedded Controller"
depends on ACPI && X86 && CROS_EC_LPC
depends on ACPI && X86 && CROS_EC_LPC && LEDS_CLASS
help
If you say Y here, you get support for talking to the ChromeOS
Wilco EC over an eSPI bus. This uses a simple byte-level protocol

3
drivers/platform/chrome/wilco_ec/Makefile
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@ -1,6 +1,7 @@
# SPDX-License-Identifier: GPL-2.0
wilco_ec-objs := core.o mailbox.o properties.o sysfs.o
wilco_ec-objs := core.o keyboard_leds.o mailbox.o \
properties.o sysfs.o
obj-$(CONFIG_WILCO_EC) += wilco_ec.o
wilco_ec_debugfs-objs := debugfs.o
obj-$(CONFIG_WILCO_EC_DEBUGFS) += wilco_ec_debugfs.o

13
drivers/platform/chrome/wilco_ec/core.c
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@ -5,10 +5,6 @@
* Copyright 2018 Google LLC
*
* This is the entry point for the drivers that control the Wilco EC.
* This driver is responsible for several tasks:
* - Initialize the register interface that is used by wilco_ec_mailbox()
* - Create a platform device which is picked up by the debugfs driver
* - Create a platform device which is picked up by the RTC driver
*/
#include <linux/acpi.h>
@ -87,6 +83,15 @@ static int wilco_ec_probe(struct platform_device *pdev)
goto unregister_debugfs;
}
/* Set up the keyboard backlight LEDs. */
ret = wilco_keyboard_leds_init(ec);
if (ret < 0) {
dev_err(dev,
"Failed to initialize keyboard LEDs: %d\n",
ret);
goto unregister_rtc;
}
ret = wilco_ec_add_sysfs(ec);
if (ret < 0) {
dev_err(dev, "Failed to create sysfs entries: %d", ret);

191
drivers/platform/chrome/wilco_ec/keyboard_leds.c Normal file
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@ -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);
}

13
include/linux/platform_data/wilco-ec.h
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@ -122,6 +122,19 @@ struct wilco_ec_message {
*/
int wilco_ec_mailbox(struct wilco_ec_device *ec, struct wilco_ec_message *msg);
/**
* wilco_keyboard_leds_init() - Set up the keyboard backlight LEDs.
* @ec: EC device to query.
*
* After this call, the keyboard backlight will be exposed through a an LED
* device at /sys/class/leds.
*
* This may sleep because it uses wilco_ec_mailbox().
*
* Return: 0 on success, negative error code on failure.
*/
int wilco_keyboard_leds_init(struct wilco_ec_device *ec);
/*
* A Property is typically a data item that is stored to NVRAM
* by the EC. Each of these data items has an index associated