[PATCH v4 2/2] power_supply: platform/chrome: wilco_ec: Add charging config driver

Nick Crews
2019-04-17T00:43:35Z

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.

v4 changes:
-Move implementation from
drivers/platform/chrome/wilco_ec/charge_config.c to
drivers/power/supply/wilco_charger.c
-Move drivers/platform/chrome/wilco_ec/properties.h to
include/linux/platform_data/wilco-ec-properties.h
-Remove parentheses in switch statement in psp_val_to_charge_mode()
-Check for any negatvie return code from psp_val_to_charge_mode()
instead of just -EINVAL so its less brittle
-Tweak comments in wilco-ec-properties.h
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@chromium.org>
---
.../ABI/testing/sysfs-class-power-wilco | 30 +++
drivers/platform/chrome/wilco_ec/Kconfig | 9 +
drivers/platform/chrome/wilco_ec/Makefile | 2 +
drivers/platform/chrome/wilco_ec/core.c | 16 ++
drivers/platform/chrome/wilco_ec/properties.c | 125 ++++++++++++
drivers/power/supply/wilco_charger.c | 190 ++++++++++++++++++
.../linux/platform_data/wilco-ec-properties.h | 68 +++++++
include/linux/platform_data/wilco-ec.h | 2 +
8 files changed, 442 insertions(+)
create mode 100644 Documentation/ABI/testing/sysfs-class-power-wilco
create mode 100644 drivers/platform/chrome/wilco_ec/properties.c
create mode 100644 drivers/power/supply/wilco_charger.c
create mode 100644 include/linux/platform_data/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/core.c b/drivers/platform/chrome/wilco_ec/core.c
index 05e1e2be1c91..c13f10d12285 100644
--- a/drivers/platform/chrome/wilco_ec/core.c
+++ b/drivers/platform/chrome/wilco_ec/core.c
@@ -89,8 +89,23 @@ 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_kbbl:
+ platform_device_unregister(ec->kbbl_pdev);
+unregister_rtc:
+ platform_device_unregister(ec->rtc_pdev);
unregister_debugfs:
if (ec->debugfs_pdev)
platform_device_unregister(ec->debugfs_pdev);
@@ -102,6 +117,7 @@ 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..49bcc413e378
--- /dev/null
+++ b/drivers/platform/chrome/wilco_ec/properties.c
@@ -0,0 +1,125 @@
+// 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 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;
+ put_unaligned_le32(prop_msg->property_id, 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;
+ put_unaligned_le32(prop_msg->property_id, 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/power/supply/wilco_charger.c b/drivers/power/supply/wilco_charger.c
new file mode 100644
index 000000000000..899b72720f63
--- /dev/null
+++ b/drivers/power/supply/wilco_charger.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 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/platform_data/wilco-ec-properties.h>
+#include <linux/power_supply.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 < 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);
+ enum charge_mode 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 = "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@chromium.org>");
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Wilco EC charge control driver");
diff --git a/include/linux/platform_data/wilco-ec-properties.h b/include/linux/platform_data/wilco-ec-properties.h
new file mode 100644
index 000000000000..acbd10d0fd0e
--- /dev/null
+++ b/include/linux/platform_data/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 "wilco-ec.h"
+
+#define WILCO_EC_PROPERTY_MAX_SIZE 4
+
+/*
+ * Properties are accessed with an operation, 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