Hi Nick,
On 3/4/19 4:05, Nick Crews wrote:
> The EC is in charge of controlling the keyboard backlight on
> the Wilco platform. We expose a standard LED class device at
> /sys/class/leds/chromeos::kbd_backlight. This driver is modeled
> after the standard Chrome OS keyboard backlight driver at
> drivers/platform/chrome/cros_kbd_led_backlight.c
>
> Some Wilco devices do not support a keyboard backlight. This
> is checked via wilco_ec_keyboard_leds_exist() in the core driver,
> and a platform_device will only be registered by the core if
> a backlight is supported.
>
> After an EC reset the backlight could be in a non-PWM mode.
> Earlier in the boot sequence the BIOS should send a command to
> the EC to set the brightness, so things **should** be set up,
> but we double check in probe() as we query the initial brightness.
> If not set up, then set the brightness to 0.
>
> Since the EC will never change the backlight level of its own accord,
> we don't need to implement a brightness_get() method.
>
> v3 changes:
> -Since this behaves the same as the standard Chrome OS keyboard
> backlight, rename the led device to "chromeos::kbd_backlight"
> -Move wilco_ec_keyboard_backlight_exists() into core module, so
> that the core does not depend upon the keyboard backlight driver.
> -This required moving some code into wilco-ec.h
> -Refactor out some common code in set_brightness() and
> initialize_brightness()
>
> v2 changes:
> -Remove and fix uses of led vs LED in kconfig
> -Assume BIOS initializes brightness, but double check in probe()
> -Remove get_brightness() callback, as EC never changes brightness
> by itself.
> -Use a __packed struct as message instead of opaque array
> -Add exported wilco_ec_keyboard_leds_exist() so the core driver
> now only creates a platform _device if relevant
> -Fix use of keyboard_led_set_brightness() since it can sleep
>
> Signed-off-by: Nick Crews <ncrews@xxxxxxxxxxxx>
> ---
> drivers/platform/chrome/wilco_ec/Kconfig | 9 +
> drivers/platform/chrome/wilco_ec/Makefile | 2 +
> drivers/platform/chrome/wilco_ec/core.c | 58 ++++++
> .../chrome/wilco_ec/kbd_led_backlight.c | 167 ++++++++++++++++++
I'm fine with this patch, I'll wait to see if any of the LEDS subsystem
maintainer can give you an ack or review.
Thanks,
Enric
> include/linux/platform_data/wilco-ec.h | 38 ++++
> 5 files changed, 274 insertions(+)
> create mode 100644 drivers/platform/chrome/wilco_ec/kbd_led_backlight.c
>
> diff --git a/drivers/platform/chrome/wilco_ec/Kconfig b/drivers/platform/chrome/wilco_ec/Kconfig
> index e09e4cebe9b4..d8cf4a60d1b5 100644
> --- a/drivers/platform/chrome/wilco_ec/Kconfig
> +++ b/drivers/platform/chrome/wilco_ec/Kconfig
> @@ -18,3 +18,12 @@ config WILCO_EC_DEBUGFS
> manipulation and allow for testing arbitrary commands. This
> interface is intended for debug only and will not be present
> on production devices.
> +
> +config WILCO_EC_KBD_BACKLIGHT
> + tristate "Enable keyboard backlight control"
> + depends on WILCO_EC
> + help
> + If you say Y here, you get support to set the keyboard backlight
> + brightness. This happens via a standard LED driver that uses the
> + Wilco EC mailbox interface. A standard LED class device will
> + appear under /sys/class/leds/chromeos::kbd_backlight
> diff --git a/drivers/platform/chrome/wilco_ec/Makefile b/drivers/platform/chrome/wilco_ec/Makefile
> index 063e7fb4ea17..8436539813cd 100644
> --- a/drivers/platform/chrome/wilco_ec/Makefile
> +++ b/drivers/platform/chrome/wilco_ec/Makefile
> @@ -4,3 +4,5 @@ wilco_ec-objs := core.o mailbox.o
> obj-$(CONFIG_WILCO_EC) += wilco_ec.o
> wilco_ec_debugfs-objs := debugfs.o
> obj-$(CONFIG_WILCO_EC_DEBUGFS) += wilco_ec_debugfs.o
> +wilco_kbd_backlight-objs := kbd_led_backlight.o
> +obj-$(CONFIG_WILCO_EC_KBD_BACKLIGHT) += wilco_kbd_backlight.o
> diff --git a/drivers/platform/chrome/wilco_ec/core.c b/drivers/platform/chrome/wilco_ec/core.c
> index 05e1e2be1c91..3c45c157b7da 100644
> --- a/drivers/platform/chrome/wilco_ec/core.c
> +++ b/drivers/platform/chrome/wilco_ec/core.c
> @@ -38,11 +38,47 @@ static struct resource *wilco_get_resource(struct platform_device *pdev,
> dev_name(dev));
> }
>
> +/**
> + * wilco_ec_keyboard_backlight_exists() - Is the keyboad backlight supported?
Typo s/keyboad/keyboard/ don't need to resend for this.
> + * @ec: EC device to query.
> + * @exists: Return value to fill in.
> + *
> + * Return: 0 on success, negative error code on failure.
> + */
> +static int wilco_ec_keyboard_backlight_exists(struct wilco_ec_device *ec,
> + bool *exists)
> +{
> + struct wilco_ec_kbbl_msg request;
> + struct wilco_ec_kbbl_msg response;
> + struct wilco_ec_message msg;
> + int ret;
> +
> + memset(&request, 0, sizeof(request));
> + request.command = WILCO_EC_COMMAND_KBBL;
> + request.subcmd = WILCO_KBBL_SUBCMD_GET_FEATURES;
> +
> + 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)
> + return ret;
> +
> + *exists = response.status != 0xFF;
> +
> + return 0;
> +}
> +
> static int wilco_ec_probe(struct platform_device *pdev)
> {
> struct device *dev = &pdev->dev;
> struct wilco_ec_device *ec;
> int ret;
> + bool kbbl_exists;
>
> ec = devm_kzalloc(dev, sizeof(*ec), GFP_KERNEL);
> if (!ec)
> @@ -89,8 +125,29 @@ static int wilco_ec_probe(struct platform_device *pdev)
> goto unregister_debugfs;
> }
>
> + /* Register child dev to be found by the keyboard backlight driver. */
> + ret = wilco_ec_keyboard_backlight_exists(ec, &kbbl_exists);
> + if (ret) {
> + dev_err(ec->dev,
> + "Failed checking keyboard backlight support: %d", ret);
> + goto unregister_rtc;
> + }
> + if (kbbl_exists) {
> + ec->kbbl_pdev = platform_device_register_data(dev,
> + "wilco-kbd-backlight",
> + PLATFORM_DEVID_AUTO, NULL, 0);
> + if (IS_ERR(ec->kbbl_pdev)) {
> + dev_err(dev,
> + "Failed to create keyboard backlight pdev\n");
> + ret = PTR_ERR(ec->kbbl_pdev);
> + goto unregister_rtc;
> + }
> + }
> +
> return 0;
>
> +unregister_rtc:
> + platform_device_unregister(ec->rtc_pdev);
> unregister_debugfs:
> if (ec->debugfs_pdev)
> platform_device_unregister(ec->debugfs_pdev);
> @@ -102,6 +159,7 @@ static int wilco_ec_remove(struct platform_device *pdev)
> {
> struct wilco_ec_device *ec = platform_get_drvdata(pdev);
>
> + platform_device_unregister(ec->kbbl_pdev);
> platform_device_unregister(ec->rtc_pdev);
> if (ec->debugfs_pdev)
> platform_device_unregister(ec->debugfs_pdev);
> diff --git a/drivers/platform/chrome/wilco_ec/kbd_led_backlight.c b/drivers/platform/chrome/wilco_ec/kbd_led_backlight.c
> new file mode 100644
> index 000000000000..922ac8717b23
> --- /dev/null
> +++ b/drivers/platform/chrome/wilco_ec/kbd_led_backlight.c
> @@ -0,0 +1,167 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Keyboard backlight LED driver for the Wilco Embedded Controller
> + *
> + * Copyright 2019 Google LLC
> + *
> + * The EC is in charge of controlling the keyboard backlight on
> + * the Wilco platform. We expose a standard LED class device at
> + * /sys/class/leds/chromeos::kbd_backlight. Power Manager normally
> + * controls the backlight by writing a percentage in range [0, 100]
> + * to the brightness property. This driver is modeled after the
> + * standard Chrome OS keyboard backlight driver at
> + * drivers/platform/chrome/cros_kbd_led_backlight.c
> + *
> + * Some Wilco devices do not support a keyboard backlight. This
> + * is checked via wilco_ec_keyboard_backlight_exists() in the core driver,
> + * and a platform_device will only be registered by the core if
> + * a backlight is supported.
> + *
> + * After an EC reset the backlight could be in a non-PWM mode.
> + * Earlier in the boot sequence the BIOS should send a command to
> + * the EC to set the brightness, so things **should** be set up,
> + * but we double check in probe() as we query the initial brightness.
> + * If not set up, then we set the brightness to KBBL_DEFAULT_BRIGHTNESS.
> + *
> + * 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/err.h>
> +#include <linux/init.h>
> +#include <linux/kernel.h>
> +#include <linux/leds.h>
> +#include <linux/module.h>
> +#include <linux/platform_data/wilco-ec.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +
> +#define DRV_NAME "wilco-kbd-backlight"
> +
> +#define KBBL_DEFAULT_BRIGHTNESS 0
> +
> +struct wilco_keyboard_led_data {
> + struct wilco_ec_device *ec;
> + struct led_classdev keyboard;
> +};
> +
> +/* Send a request, get a response, and check that the response is good. */
> +static int send_kbbl_msg(struct wilco_ec_device *ec,
> + const struct wilco_ec_kbbl_msg *request,
> + struct wilco_ec_kbbl_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 brightness command: %d", ret);
> +
> + if (response->status) {
> + dev_err(ec->dev,
> + "EC reported failure sending brightness command: %d",
> + response->status);
> + return -EIO;
> + }
> +
> + return 0;
> +}
> +
> +/* This may sleep because it uses wilco_ec_mailbox() */
> +static int keyboard_led_set_brightness(struct led_classdev *cdev,
> + enum led_brightness brightness)
> +{
> + struct wilco_ec_kbbl_msg request;
> + struct wilco_ec_kbbl_msg response;
> + struct wilco_keyboard_led_data *data;
> +
> + memset(&request, 0, sizeof(request));
> + request.command = WILCO_EC_COMMAND_KBBL;
> + request.subcmd = WILCO_KBBL_SUBCMD_GET_STATE;
> + request.mode = WILCO_KBBL_MODE_FLAG_PWM;
> + request.percent = brightness;
> +
> + data = container_of(cdev, struct wilco_keyboard_led_data, keyboard);
> + return send_kbbl_msg(data->ec, &request, &response);
> +}
> +
> +/*
> + * Get the current brightness, ensuring that we are in PWM mode. If not
> + * in PWM mode, then the current brightness is meaningless, so set the
> + * brightness to KBBL_DEFAULT_BRIGHTNESS.
> + *
> + * Return: Final brightness of the keyboard, or negative error code on failure.
> + */
> +static int initialize_brightness(struct wilco_keyboard_led_data *data)
> +{
> + struct wilco_ec_kbbl_msg request;
> + struct wilco_ec_kbbl_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(data->ec, &request, &response);
> + if (ret < 0)
> + return ret;
> +
> + if (response.mode & WILCO_KBBL_MODE_FLAG_PWM)
> + return response.percent;
> +
> + dev_warn(data->ec->dev, "Keyboard brightness not initialized by BIOS");
> + ret = led_set_brightness_sync(&data->keyboard, KBBL_DEFAULT_BRIGHTNESS);
> + if (ret < 0)
> + return ret;
> +
> + return KBBL_DEFAULT_BRIGHTNESS;
> +}
> +
> +static int keyboard_led_probe(struct platform_device *pdev)
> +{
> + struct wilco_ec_device *ec = dev_get_drvdata(pdev->dev.parent);
> + struct wilco_keyboard_led_data *data;
> + int ret;
> +
> + data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
> + if (!data)
> + return -ENOMEM;
> +
> + data->ec = ec;
> + /* This acts the same as the CrOS backlight, so use the same name */
> + data->keyboard.name = "chromeos::kbd_backlight";
> + data->keyboard.max_brightness = 100;
> + data->keyboard.flags = LED_CORE_SUSPENDRESUME;
> + data->keyboard.brightness_set_blocking = keyboard_led_set_brightness;
> + ret = initialize_brightness(data);
> + if (ret < 0)
> + return ret;
> + data->keyboard.brightness = ret;
> +
> + ret = devm_led_classdev_register(&pdev->dev, &data->keyboard);
> + if (ret)
> + return ret;
> +
> + return 0;
> +}
> +
> +static struct platform_driver keyboard_led_driver = {
> + .driver = {
> + .name = DRV_NAME,
> + },
> + .probe = keyboard_led_probe,
> +};
> +module_platform_driver(keyboard_led_driver);
> +
> +MODULE_AUTHOR("Nick Crews <ncrews@xxxxxxxxxxxx>");
> +MODULE_DESCRIPTION("Wilco keyboard backlight LED driver");
> +MODULE_LICENSE("GPL v2");
> +MODULE_ALIAS("platform:" DRV_NAME);
> diff --git a/include/linux/platform_data/wilco-ec.h b/include/linux/platform_data/wilco-ec.h
> index 1ff224793c99..c3965b7f397d 100644
> --- a/include/linux/platform_data/wilco-ec.h
> +++ b/include/linux/platform_data/wilco-ec.h
> @@ -32,6 +32,7 @@
> * @data_size: Size of the data buffer used for EC communication.
> * @debugfs_pdev: The child platform_device used by the debugfs sub-driver.
> * @rtc_pdev: The child platform_device used by the RTC sub-driver.
> + * @kbbl_pdev: The child pdev used by the keyboard backlight sub-driver.
> */
> struct wilco_ec_device {
> struct device *dev;
> @@ -43,6 +44,7 @@ struct wilco_ec_device {
> size_t data_size;
> struct platform_device *debugfs_pdev;
> struct platform_device *rtc_pdev;
> + struct platform_device *kbbl_pdev;
> };
>
> /**
> @@ -114,6 +116,42 @@ struct wilco_ec_message {
> void *response_data;
> };
>
> +/* Constants and structs useful for keyboard backlight (KBBL) control */
> +
> +#define WILCO_EC_COMMAND_KBBL 0x75
> +#define WILCO_KBBL_MODE_FLAG_PWM BIT(1) /* Set brightness by percent. */
> +
> +/**
> + * enum kbbl_subcommand - What action does the EC perform?
> + * @WILCO_KBBL_SUBCMD_GET_FEATURES: Request available functionality from EC.
> + * @WILCO_KBBL_SUBCMD_GET_STATE: Request current mode and brightness from EC.
> + * @WILCO_KBBL_SUBCMD_SET_STATE: Write mode and brightness to EC.
> + */
> +enum kbbl_subcommand {
> + WILCO_KBBL_SUBCMD_GET_FEATURES = 0x00,
> + WILCO_KBBL_SUBCMD_GET_STATE = 0x01,
> + WILCO_KBBL_SUBCMD_SET_STATE = 0x02,
> +};
> +
> +/**
> + * struct wilco_ec_kbbl_msg - Message to/from EC for keyboard backlight control.
> + * @command: Always WILCO_EC_COMMAND_KBBL.
> + * @status: Set by EC to 0 on success, 0xFF on failure.
> + * @subcmd: One of enum kbbl_subcommand.
> + * @mode: Bit flags for used mode, we want to use WILCO_KBBL_MODE_FLAG_PWM.
> + * @percent: Brightness in 0-100. Only meaningful in PWM mode.
> + */
> +struct wilco_ec_kbbl_msg {
> + u8 command;
> + u8 status;
> + u8 subcmd;
> + u8 reserved3;
> + u8 mode;
> + u8 reserved5to8[4];
> + u8 percent;
> + u8 reserved10to15[6];
> +} __packed;
> +
> /**
> * wilco_ec_mailbox() - Send request to the EC and receive the response.
> * @ec: Wilco EC device.
>
