Message-Id: <20190412002055.92529-2-ncrews@chromium.org>
Date:   Thu, 11 Apr 2019 18:20:55 -0600
From:   Nick Crews <ncrews@...omium.org>
To:     enric.balletbo@...labora.com, bleung@...omium.org, sre@...nel.org,
        linux-pm@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, dlaurie@...omium.org,
        lamzin@...gle.com, bartfab@...gle.com, derat@...gle.com,
        groeck@...gle.com, dtor@...gle.com, sjg@...omium.org,
        jchwong@...omium.org, Nick Crews <ncrews@...omium.org>
Subject: [PATCH v3 2/2] power_supply: platform/chrome: wilco_ec: Add charging config driver

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

v3 changes:
-Add this changelog
-Fix commit message tags
v2 changes:
-Update Documentation to say KernelVersion 5.2
-Update Documentation to explain Trickle mode better.
-rename things from using *PCC* to *CHARGE*
-Split up conversions between POWER_SUPPLY_PROP_CHARGE_TYPE values
and Wilco EC codes
-Use devm_ flavor of power_supply_register(), which simplifies things
-Add extra error checking on property messages received from the EC
-Fix bug in memcpy() calls in properties.c
-Refactor fill_property_id()
-Add valid input checks to charge_type
-Properly convert charge_type when get()ting

Signed-off-by: Nick Crews <ncrews@...omium.org>
---
 .../ABI/testing/sysfs-class-power-wilco       |  30 +++
 drivers/platform/chrome/wilco_ec/Kconfig      |   9 +
 drivers/platform/chrome/wilco_ec/Makefile     |   2 +
 .../platform/chrome/wilco_ec/charge_config.c  | 190 ++++++++++++++++++
 drivers/platform/chrome/wilco_ec/core.c       |  14 ++
 drivers/platform/chrome/wilco_ec/properties.c | 134 ++++++++++++
 drivers/platform/chrome/wilco_ec/properties.h |  68 +++++++
 include/linux/platform_data/wilco-ec.h        |   2 +
 8 files changed, 449 insertions(+)
 create mode 100644 Documentation/ABI/testing/sysfs-class-power-wilco
 create mode 100644 drivers/platform/chrome/wilco_ec/charge_config.c
 create mode 100644 drivers/platform/chrome/wilco_ec/properties.c
 create mode 100644 drivers/platform/chrome/wilco_ec/properties.h

diff --git a/Documentation/ABI/testing/sysfs-class-power-wilco b/Documentation/ABI/testing/sysfs-class-power-wilco
new file mode 100644
index 000000000000..7f3b01310476
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-power-wilco
@@ -0,0 +1,30 @@
+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].
diff --git a/drivers/platform/chrome/wilco_ec/Kconfig b/drivers/platform/chrome/wilco_ec/Kconfig
index e09e4cebe9b4..1c427830bd57 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_CHARGE_CNTL
+	tristate "Enable charging control"
+	depends on WILCO_EC
+	help
+	  If you say Y here, you get support to control the charging
+	  routines performed by the Wilco Embedded Controller.
+	  Further information can be found in
+	  Documentation/ABI/testing/sysfs-class-power-wilco)
diff --git a/drivers/platform/chrome/wilco_ec/Makefile b/drivers/platform/chrome/wilco_ec/Makefile
index 063e7fb4ea17..7e980f56f793 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_ec_charging-objs			:= charge_config.o properties.o
+obj-$(CONFIG_WILCO_EC_CHARGE_CNTL)	+= wilco_ec_charging.o
diff --git a/drivers/platform/chrome/wilco_ec/charge_config.c b/drivers/platform/chrome/wilco_ec/charge_config.c
new file mode 100644
index 000000000000..7c41b847396d
--- /dev/null
+++ b/drivers/platform/chrome/wilco_ec/charge_config.c
@@ -0,0 +1,190 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Charging control driver for the Wilco EC
+ *
+ * Copyright 2019 Google LLC
+ *
+ * See 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>
+
+#include "properties.h"
+
+#define DRV_NAME "wilco-ec-charging"
+
+/* 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 enum charge_mode 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 == -EINVAL)
+			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);
+	enum charge_mode mode;
+
+	switch (psp) {
+	case POWER_SUPPLY_PROP_CHARGE_TYPE:
+		mode = psp_val_to_charge_mode(val->intval);
+		if (mode == -EINVAL)
+			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			= "wilco-charger",
+	.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);
+	if (IS_ERR(psy))
+		return PTR_ERR(psy);
+
+	return 0;
+}
+
+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@...omium.org>");
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Wilco EC charge control driver");
diff --git a/drivers/platform/chrome/wilco_ec/core.c b/drivers/platform/chrome/wilco_ec/core.c
index 05e1e2be1c91..b6f3b061f37b 100644
--- a/drivers/platform/chrome/wilco_ec/core.c
+++ b/drivers/platform/chrome/wilco_ec/core.c
@@ -89,8 +89,21 @@ static int wilco_ec_probe(struct platform_device *pdev)
 		goto unregister_debugfs;
 	}
 
+	/* Register child device to be found by charging config driver. */
+	ec->charging_pdev = platform_device_register_data(dev,
+							  "wilco-ec-charging",
+							  PLATFORM_DEVID_AUTO,
+							  NULL, 0);
+	if (IS_ERR(ec->charging_pdev)) {
+		dev_err(dev, "Failed to create charging platform device\n");
+		ret = PTR_ERR(ec->charging_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 +115,7 @@ static int wilco_ec_remove(struct platform_device *pdev)
 {
 	struct wilco_ec_device *ec = platform_get_drvdata(pdev);
 
+	platform_device_unregister(ec->charging_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/properties.c b/drivers/platform/chrome/wilco_ec/properties.c
new file mode 100644
index 000000000000..d74eb1208afd
--- /dev/null
+++ b/drivers/platform/chrome/wilco_ec/properties.c
@@ -0,0 +1,134 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2019 Google LLC
+ */
+
+#include <linux/string.h>
+#include "properties.h"
+
+struct ec_property_request {
+	u8 op;
+	u8 property_id[4];
+	u8 length;
+	u8 data[WILCO_EC_PROPERTY_MAX_SIZE];
+} __packed;
+
+struct ec_property_response {
+	u8 reserved[2];
+	u8 op;
+	u8 property_id[4];
+	u8 length;
+	u8 data[WILCO_EC_PROPERTY_MAX_SIZE];
+} __packed;
+
+static inline void fill_request_property_id(struct ec_property_request *rq,
+					    u32 property_id)
+{
+	rq->property_id[0] =  property_id        & 0xff;
+	rq->property_id[1] = (property_id >> 8)  & 0xff;
+	rq->property_id[2] = (property_id >> 16) & 0xff;
+	rq->property_id[3] = (property_id >> 24) & 0xff;
+}
+
+static int send_property_msg(struct wilco_ec_device *ec,
+			     struct ec_property_request *rq,
+			     struct ec_property_response *rs)
+{
+	struct wilco_ec_message ec_msg;
+	int ret;
+
+	memset(&ec_msg, 0, sizeof(ec_msg));
+	ec_msg.type = WILCO_EC_MSG_PROPERTY;
+	ec_msg.request_data = rq;
+	ec_msg.request_size = sizeof(*rq);
+	ec_msg.response_data = rs;
+	ec_msg.response_size = sizeof(*rs);
+	ret = wilco_ec_mailbox(ec, &ec_msg);
+	if (ret < 0)
+		return ret;
+
+	if (rs->op != rq->op)
+		return -EBADMSG;
+	if (memcmp(rq->property_id, rs->property_id, sizeof(rs->property_id)))
+		return -EBADMSG;
+	if (rs->length > sizeof(rs->data))
+		return -EMSGSIZE;
+
+	return 0;
+}
+
+int wilco_ec_get_property(struct wilco_ec_device *ec,
+			  struct ec_property_get_msg *prop_msg)
+{
+	struct ec_property_request rq;
+	struct ec_property_response rs;
+	int ret;
+
+	memset(&rq, 0, sizeof(rq));
+	rq.op = OP_GET;
+	fill_request_property_id(&rq, prop_msg->property_id);
+
+	ret = send_property_msg(ec, &rq, &rs);
+	if (ret < 0)
+		return ret;
+
+	prop_msg->length = rs.length;
+	memcpy(prop_msg->data, rs.data, rs.length);
+
+	return 0;
+}
+
+int wilco_ec_set_property(struct wilco_ec_device *ec,
+			  struct ec_property_set_msg *prop_msg)
+{
+	struct ec_property_request rq;
+	struct ec_property_response rs;
+	int ret;
+
+	memset(&rq, 0, sizeof(rq));
+	rq.op = prop_msg->op;
+	fill_request_property_id(&rq, prop_msg->property_id);
+	rq.length = prop_msg->length;
+	memcpy(rq.data, prop_msg->data, prop_msg->length);
+
+	ret = send_property_msg(ec, &rq, &rs);
+	if (ret < 0)
+		return ret;
+
+	if (rs.length != prop_msg->length)
+		return -EBADMSG;
+
+	return 0;
+}
+
+int wilco_ec_get_byte_property(struct wilco_ec_device *ec, u32 property_id,
+			       u8 *val)
+{
+	struct ec_property_get_msg msg;
+	int ret;
+
+	msg.property_id = property_id;
+	ret = wilco_ec_get_property(ec, &msg);
+	if (ret)
+		return ret;
+
+	if (msg.length != 1)
+		return -EBADMSG;
+
+	*val = msg.data[0];
+
+	return 0;
+}
+
+int wilco_ec_set_byte_property(struct wilco_ec_device *ec, u32 property_id,
+			       u8 val)
+{
+	struct ec_property_set_msg msg;
+
+	msg.property_id = property_id;
+	msg.op = OP_SET;
+	msg.data[0] = val;
+	msg.length = 1;
+
+	return wilco_ec_set_property(ec, &msg);
+}
diff --git a/drivers/platform/chrome/wilco_ec/properties.h b/drivers/platform/chrome/wilco_ec/properties.h
new file mode 100644
index 000000000000..da0bb3b869af
--- /dev/null
+++ b/drivers/platform/chrome/wilco_ec/properties.h
@@ -0,0 +1,68 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Helper library for property access on the Wilco EC.
+ *
+ * Copyright 2019 Google LLC
+ *
+ * A Property is typically a data item that is stored to NVRAM
+ * by the EC. Each of these data items has an index associated
+ * with it known as the Property ID (PID). Properties may have
+ * variable lengths, up to a max of WILCO_EC_PROPERTY_MAX_SIZE
+ * bytes. Properties can be simple integers, or they may be more
+ * complex binary data.
+ */
+
+#include <linux/platform_data/wilco-ec.h>
+
+#define WILCO_EC_PROPERTY_MAX_SIZE	4
+
+/*
+ * Properties are accessed with an subcommand, or "op". OP_GET
+ * requests the property from the EC. OP_SET and OP_SYNC do the
+ * exact same thing from our perspective: save a property. Only
+ * one of them works for a given property, so each property uses
+ * either OP_GET and OP_SET, or OP_GET and OP_SYNC.
+ */
+enum get_set_sync_op {
+	OP_GET = 0,
+	OP_SET = 1,
+	OP_SYNC = 4
+};
+
+/**
+ * struct ec_property_get_msg - Message to retrieve a property.
+ * @property_id: PID of property to retrieve.
+ * @length: number of bytes received, set by wilco_ec_get_property().
+ * @data: actual property data, set by wilco_ec_get_property().
+ */
+struct ec_property_get_msg {
+	u32 property_id;
+	int length;
+	u8 data[WILCO_EC_PROPERTY_MAX_SIZE];
+};
+
+/**
+ * struct ec_property_set_msg - Message to save a property.
+ * @op: Which subcommand to use, either OP_SET or OP_SYNC
+ * @property_id: PID of property to save.
+ * @length: number of bytes to save, must not exceed WILCO_EC_PROPERTY_MAX_SIZE.
+ * @data: actual property data.
+ */
+struct ec_property_set_msg {
+	enum get_set_sync_op op;
+	u32 property_id;
+	int length;
+	u8 data[WILCO_EC_PROPERTY_MAX_SIZE];
+};
+
+/* Both of these will return 0 on success, negative error code on failure */
+int wilco_ec_get_property(struct wilco_ec_device *ec,
+			  struct ec_property_get_msg *prop_msg);
+int wilco_ec_set_property(struct wilco_ec_device *ec,
+			  struct ec_property_set_msg *prop_msg);
+
+/* Both of these will return 0 on success, negative error code on failure */
+int wilco_ec_get_byte_property(struct wilco_ec_device *ec, u32 property_id,
+			       u8 *val);
+int wilco_ec_set_byte_property(struct wilco_ec_device *ec, u32 property_id,
+			       u8 val);
diff --git a/include/linux/platform_data/wilco-ec.h b/include/linux/platform_data/wilco-ec.h
index 1ff224793c99..4e7dce897500 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.
+ * @charging_pdev: Child platform_device used by the charging config 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 *charging_pdev;
 };
 
 /**
-- 
2.20.1

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