Commit 3f57fe28 authored by Nick Crews's avatar Nick Crews Committed by Sebastian Reichel
Browse files

power_supply: wilco_ec: Add charging config driver 



Add a driver to control the charging algorithm used on Wilco
devices. See Documentation/ABI/testing/sysfs-class-power-wilco
for the userspace interface and other info.

Signed-off-by: default avatarNick Crews <ncrews@chromium.org>
Reviewed-by: default avatarEnric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: default avatarSebastian Reichel <sebastian.reichel@collabora.com>
parent 1e10694d

Documentation/ABI/testing/sysfs-class-power-wilco

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What:		/sys/class/power_supply/wilco-charger/charge_type

Date:		April 2019

KernelVersion:	5.2

Description:

		What charging algorithm to use:



		Standard: Fully charges battery at a standard rate.

		Adaptive: Battery settings adaptively optimized based on

			typical battery usage pattern.

		Fast: Battery charges over a shorter period.

		Trickle: Extends battery lifespan, intended for users who

			primarily use their Chromebook while connected to AC.

		Custom: A low and high threshold percentage is specified.

			Charging begins when level drops below

			charge_control_start_threshold, and ceases when

			level is above charge_control_end_threshold.



What:		/sys/class/power_supply/wilco-charger/charge_control_start_threshold

Date:		April 2019

KernelVersion:	5.2

Description:

		Used when charge_type="Custom", as described above. Measured in

		percentages. The valid range is [50, 95].



What:		/sys/class/power_supply/wilco-charger/charge_control_end_threshold

Date:		April 2019

KernelVersion:	5.2

Description:

		Used when charge_type="Custom", as described above. Measured in

		percentages. The valid range is [55, 100].

drivers/power/supply/Kconfig

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@@ -702,4 +702,13 @@ config CHARGER_UCS1002 
	  Say Y to enable support for Microchip UCS1002 Programmable

	  Say Y to enable support for Microchip UCS1002 Programmable

	  USB Port Power Controller with Charger Emulation.

	  USB Port Power Controller with Charger Emulation.





config CHARGER_WILCO

	tristate "Wilco EC based charger for ChromeOS"

	depends on WILCO_EC

	help

	  Say Y here to enable control of the charging routines performed

	  by the Embedded Controller on the Chromebook named Wilco. Further

	  information can be found in

	  Documentation/ABI/testing/sysfs-class-power-wilco



endif # POWER_SUPPLY
 
endif # POWER_SUPPLY

drivers/power/supply/Makefile

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@@ -91,3 +91,4 @@ obj-$(CONFIG_CHARGER_CROS_USBPD) += cros_usbpd-charger.o 
obj-$(CONFIG_CHARGER_SC2731)	+= sc2731_charger.o

obj-$(CONFIG_CHARGER_SC2731)	+= sc2731_charger.o

obj-$(CONFIG_FUEL_GAUGE_SC27XX)	+= sc27xx_fuel_gauge.o

obj-$(CONFIG_FUEL_GAUGE_SC27XX)	+= sc27xx_fuel_gauge.o

obj-$(CONFIG_CHARGER_UCS1002)	+= ucs1002_power.o

obj-$(CONFIG_CHARGER_UCS1002)	+= ucs1002_power.o

obj-$(CONFIG_CHARGER_WILCO)	+= wilco-charger.o

drivers/power/supply/wilco-charger.c

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// SPDX-License-Identifier: GPL-2.0

/*

 * Charging control driver for the Wilco EC

 *

 * Copyright 2019 Google LLC

 *

 * See Documentation/ABI/testing/sysfs-class-power and

 * Documentation/ABI/testing/sysfs-class-power-wilco for userspace interface

 * and other info.

 */



#include <linux/module.h>

#include <linux/platform_device.h>

#include <linux/platform_data/wilco-ec.h>

#include <linux/power_supply.h>



#define DRV_NAME "wilco-charger"



/* Property IDs and related EC constants */

#define PID_CHARGE_MODE		0x0710

#define PID_CHARGE_LOWER_LIMIT	0x0711

#define PID_CHARGE_UPPER_LIMIT	0x0712



enum charge_mode {

	CHARGE_MODE_STD = 1,	/* Used for Standard */

	CHARGE_MODE_EXP = 2,	/* Express Charge, used for Fast */

	CHARGE_MODE_AC = 3,	/* Mostly AC use, used for Trickle */

	CHARGE_MODE_AUTO = 4,	/* Used for Adaptive */

	CHARGE_MODE_CUSTOM = 5,	/* Used for Custom */

};



#define CHARGE_LOWER_LIMIT_MIN	50

#define CHARGE_LOWER_LIMIT_MAX	95

#define CHARGE_UPPER_LIMIT_MIN	55

#define CHARGE_UPPER_LIMIT_MAX	100



/* Convert from POWER_SUPPLY_PROP_CHARGE_TYPE value to the EC's charge mode */

static int psp_val_to_charge_mode(int psp_val)

{

	switch (psp_val) {

	case POWER_SUPPLY_CHARGE_TYPE_TRICKLE:

		return CHARGE_MODE_AC;

	case POWER_SUPPLY_CHARGE_TYPE_FAST:

		return CHARGE_MODE_EXP;

	case POWER_SUPPLY_CHARGE_TYPE_STANDARD:

		return CHARGE_MODE_STD;

	case POWER_SUPPLY_CHARGE_TYPE_ADAPTIVE:

		return CHARGE_MODE_AUTO;

	case POWER_SUPPLY_CHARGE_TYPE_CUSTOM:

		return CHARGE_MODE_CUSTOM;

	default:

		return -EINVAL;

	}

}



/* Convert from EC's charge mode to POWER_SUPPLY_PROP_CHARGE_TYPE value */

static int charge_mode_to_psp_val(enum charge_mode mode)

{

	switch (mode) {

	case CHARGE_MODE_AC:

		return POWER_SUPPLY_CHARGE_TYPE_TRICKLE;

	case CHARGE_MODE_EXP:

		return POWER_SUPPLY_CHARGE_TYPE_FAST;

	case CHARGE_MODE_STD:

		return POWER_SUPPLY_CHARGE_TYPE_STANDARD;

	case CHARGE_MODE_AUTO:

		return POWER_SUPPLY_CHARGE_TYPE_ADAPTIVE;

	case CHARGE_MODE_CUSTOM:

		return POWER_SUPPLY_CHARGE_TYPE_CUSTOM;

	default:

		return -EINVAL;

	}

}



static enum power_supply_property wilco_charge_props[] = {

	POWER_SUPPLY_PROP_CHARGE_TYPE,

	POWER_SUPPLY_PROP_CHARGE_CONTROL_START_THRESHOLD,

	POWER_SUPPLY_PROP_CHARGE_CONTROL_END_THRESHOLD,

};



static int wilco_charge_get_property(struct power_supply *psy,

				     enum power_supply_property psp,

				     union power_supply_propval *val)

{

	struct wilco_ec_device *ec = power_supply_get_drvdata(psy);

	u32 property_id;

	int ret;

	u8 raw;



	switch (psp) {

	case POWER_SUPPLY_PROP_CHARGE_TYPE:

		property_id = PID_CHARGE_MODE;

		break;

	case POWER_SUPPLY_PROP_CHARGE_CONTROL_START_THRESHOLD:

		property_id = PID_CHARGE_LOWER_LIMIT;

		break;

	case POWER_SUPPLY_PROP_CHARGE_CONTROL_END_THRESHOLD:

		property_id = PID_CHARGE_UPPER_LIMIT;

		break;

	default:

		return -EINVAL;

	}



	ret = wilco_ec_get_byte_property(ec, property_id, &raw);

	if (ret < 0)

		return ret;

	if (property_id == PID_CHARGE_MODE) {

		ret = charge_mode_to_psp_val(raw);

		if (ret < 0)

			return -EBADMSG;

		raw = ret;

	}

	val->intval = raw;



	return 0;

}



static int wilco_charge_set_property(struct power_supply *psy,

				     enum power_supply_property psp,

				     const union power_supply_propval *val)

{

	struct wilco_ec_device *ec = power_supply_get_drvdata(psy);

	int mode;



	switch (psp) {

	case POWER_SUPPLY_PROP_CHARGE_TYPE:

		mode = psp_val_to_charge_mode(val->intval);

		if (mode < 0)

			return -EINVAL;

		return wilco_ec_set_byte_property(ec, PID_CHARGE_MODE, mode);

	case POWER_SUPPLY_PROP_CHARGE_CONTROL_START_THRESHOLD:

		if (val->intval < CHARGE_LOWER_LIMIT_MIN ||

		    val->intval > CHARGE_LOWER_LIMIT_MAX)

			return -EINVAL;

		return wilco_ec_set_byte_property(ec, PID_CHARGE_LOWER_LIMIT,

						  val->intval);

	case POWER_SUPPLY_PROP_CHARGE_CONTROL_END_THRESHOLD:

		if (val->intval < CHARGE_UPPER_LIMIT_MIN ||

		    val->intval > CHARGE_UPPER_LIMIT_MAX)

			return -EINVAL;

		return wilco_ec_set_byte_property(ec, PID_CHARGE_UPPER_LIMIT,

						  val->intval);

	default:

		return -EINVAL;

	}

}



static int wilco_charge_property_is_writeable(struct power_supply *psy,

					      enum power_supply_property psp)

{

	return 1;

}



static const struct power_supply_desc wilco_ps_desc = {

	.properties		= wilco_charge_props,

	.num_properties		= ARRAY_SIZE(wilco_charge_props),

	.get_property		= wilco_charge_get_property,

	.set_property		= wilco_charge_set_property,

	.property_is_writeable	= wilco_charge_property_is_writeable,

	.name			= DRV_NAME,

	.type			= POWER_SUPPLY_TYPE_MAINS,

};



static int wilco_charge_probe(struct platform_device *pdev)

{

	struct wilco_ec_device *ec = dev_get_drvdata(pdev->dev.parent);

	struct power_supply_config psy_cfg = {};

	struct power_supply *psy;



	psy_cfg.drv_data = ec;

	psy = devm_power_supply_register(&pdev->dev, &wilco_ps_desc, &psy_cfg);



	return PTR_ERR_OR_ZERO(psy);

}



static struct platform_driver wilco_charge_driver = {

	.probe	= wilco_charge_probe,

	.driver = {

		.name = DRV_NAME,

	}

};

module_platform_driver(wilco_charge_driver);



MODULE_ALIAS("platform:" DRV_NAME);

MODULE_AUTHOR("Nick Crews <ncrews@chromium.org>");

MODULE_LICENSE("GPL v2");

MODULE_DESCRIPTION("Wilco EC charge control driver");

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