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Subject[PATCH 2/2] power_supply: wilco_ec: Add charging config driver for Wilco EC
Date
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.

Signed-off-by: Nick Crews <ncrews@chromium.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 | 182 ++++++++++++++++++
drivers/platform/chrome/wilco_ec/core.c | 14 ++
drivers/platform/chrome/wilco_ec/properties.c | 129 +++++++++++++
drivers/platform/chrome/wilco_ec/properties.h | 68 +++++++
include/linux/platform_data/wilco-ec.h | 2 +
8 files changed, 436 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..ef78e3d4a4bd
--- /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: 5.1
+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 for users who use
+ their Chromebooks 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: 5.1
+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: 5.1
+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..907526829444
--- /dev/null
+++ b/drivers/platform/chrome/wilco_ec/charge_config.c
@@ -0,0 +1,182 @@
+// 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_PCC_MODE 0x0710
+#define PID_PCC_LOWER_LIMIT 0x0711
+#define PID_PCC_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 PCC_LOWER_LIMIT_MIN 50
+#define PCC_LOWER_LIMIT_MAX 95
+#define PCC_UPPER_LIMIT_MIN 55
+#define PCC_UPPER_LIMIT_MAX 100
+
+static int set_charge_type(struct wilco_ec_device *ec, int psp_val)
+{
+ enum charge_mode mode;
+
+ switch (psp_val) {
+ case (POWER_SUPPLY_CHARGE_TYPE_TRICKLE):
+ mode = CHARGE_MODE_AC;
+ break;
+ case (POWER_SUPPLY_CHARGE_TYPE_FAST):
+ mode = CHARGE_MODE_EXP;
+ break;
+ case (POWER_SUPPLY_CHARGE_TYPE_STANDARD):
+ mode = CHARGE_MODE_STD;
+ break;
+ case (POWER_SUPPLY_CHARGE_TYPE_ADAPTIVE):
+ mode = CHARGE_MODE_AUTO;
+ break;
+ case (POWER_SUPPLY_CHARGE_TYPE_CUSTOM):
+ mode = CHARGE_MODE_CUSTOM;
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ return wilco_ec_set_byte_property(ec, PID_PCC_MODE, mode);
+}
+
+static enum power_supply_property wilco_pcc_props[] = {
+ POWER_SUPPLY_PROP_CHARGE_TYPE,
+ POWER_SUPPLY_PROP_CHARGE_CONTROL_START_THRESHOLD,
+ POWER_SUPPLY_PROP_CHARGE_CONTROL_END_THRESHOLD,
+};
+
+struct wilco_pcc_data {
+ struct wilco_ec_device *ec;
+ struct power_supply *psy;
+};
+
+static int wilco_pcc_get_property(struct power_supply *psy,
+ enum power_supply_property psp,
+ union power_supply_propval *val)
+{
+ struct wilco_pcc_data *data = power_supply_get_drvdata(psy);
+ struct wilco_ec_device *ec = data->ec;
+
+ switch (psp) {
+ case POWER_SUPPLY_PROP_CHARGE_TYPE:
+ return wilco_ec_get_byte_property(ec, PID_PCC_MODE,
+ (u8 *)&val->intval);
+ case POWER_SUPPLY_PROP_CHARGE_CONTROL_START_THRESHOLD:
+ return wilco_ec_get_byte_property(ec, PID_PCC_LOWER_LIMIT,
+ (u8 *)&val->intval);
+ case POWER_SUPPLY_PROP_CHARGE_CONTROL_END_THRESHOLD:
+ return wilco_ec_get_byte_property(ec, PID_PCC_UPPER_LIMIT,
+ (u8 *)&val->intval);
+ default:
+ return -EINVAL;
+ }
+}
+
+static int wilco_pcc_set_property(struct power_supply *psy,
+ enum power_supply_property psp,
+ const union power_supply_propval *val)
+{
+ struct wilco_pcc_data *data = power_supply_get_drvdata(psy);
+ struct wilco_ec_device *ec = data->ec;
+
+ switch (psp) {
+ case POWER_SUPPLY_PROP_CHARGE_TYPE:
+ return set_charge_type(ec, val->intval);
+ case POWER_SUPPLY_PROP_CHARGE_CONTROL_START_THRESHOLD:
+ if (val->intval < PCC_LOWER_LIMIT_MIN ||
+ val->intval > PCC_LOWER_LIMIT_MAX)
+ return -EINVAL;
+ return wilco_ec_set_byte_property(ec, PID_PCC_LOWER_LIMIT,
+ val->intval);
+ case POWER_SUPPLY_PROP_CHARGE_CONTROL_END_THRESHOLD:
+ if (val->intval < PCC_UPPER_LIMIT_MIN ||
+ val->intval > PCC_UPPER_LIMIT_MAX)
+ return -EINVAL;
+ return wilco_ec_set_byte_property(ec, PID_PCC_UPPER_LIMIT,
+ val->intval);
+ default:
+ return -EINVAL;
+ }
+}
+
+static int wilco_pcc_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_pcc_props,
+ .num_properties = ARRAY_SIZE(wilco_pcc_props),
+ .get_property = wilco_pcc_get_property,
+ .set_property = wilco_pcc_set_property,
+ .property_is_writeable = wilco_pcc_property_is_writeable,
+ .name = "wilco-charger",
+ .type = POWER_SUPPLY_TYPE_MAINS,
+};
+
+static int wilco_pcc_probe(struct platform_device *pdev)
+{
+ struct wilco_ec_device *ec = dev_get_drvdata(pdev->dev.parent);
+ struct power_supply_config psy_cfg = {};
+ struct wilco_pcc_data *data;
+
+ data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ data->ec = ec;
+ psy_cfg.drv_data = data;
+ platform_set_drvdata(pdev, data);
+
+ data->psy = power_supply_register(&pdev->dev, &wilco_ps_desc, &psy_cfg);
+ if (IS_ERR(data->psy))
+ return PTR_ERR(data->psy);
+
+ return 0;
+}
+
+static int wilco_pcc_remove(struct platform_device *pdev)
+{
+ struct wilco_pcc_data *data = platform_get_drvdata(pdev);
+
+ power_supply_unregister(data->psy);
+ return 0;
+}
+
+static struct platform_driver wilco_pcc_driver = {
+ .probe = wilco_pcc_probe,
+ .remove = wilco_pcc_remove,
+ .driver = {
+ .name = DRV_NAME,
+ }
+};
+module_platform_driver(wilco_pcc_driver);
+
+MODULE_ALIAS("platform:" DRV_NAME);
+MODULE_AUTHOR("Nick Crews <ncrews@chromium.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..67fdf6208a9c
--- /dev/null
+++ b/drivers/platform/chrome/wilco_ec/properties.c
@@ -0,0 +1,129 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2019 Google LLC
+ */
+
+#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;
+
+/* Store a 32 bit property ID into a byte array, LSB first */
+static inline void fill_property_id(u32 property_id, u8 field[])
+{
+ field[0] = property_id & 0xff;
+ field[1] = (property_id >> 8) & 0xff;
+ field[2] = (property_id >> 16) & 0xff;
+ field[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;
+
+ 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_property_id(prop_msg->property_id, (u8 *)&rq.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_property_id(prop_msg->property_id, (u8 *)&rq.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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