[PATCH v6 2/2] power_supply: platform/chrome: wilco_ec: Add charging config driver

From: Nick Crews
Date: Mon Apr 22 2019 - 14:05:41 EST

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@xxxxxxxxxxxx>
---
v6 changes:
-Remove CHARGE_MODE_ILLEGAL from enum charge_mode. It's not a
public type, and error checking could be performed in other ways.
-Split up the commit so properties are added in a first commit
-Move CONFIG_CHARGER_WILCO to the power/supply Kconfig
-Use PTR_ERR_OR_ZERO() macro in probe()
v5 changes:
-Remove OP_SYNC, it has no immediate use case.
-Merge properties.h into wilco-ec.h
-Remove enum get_set_sync_op from the public interface,
since without OP_SYNC they are irrelevant.
-Fix Kconfigs and Makefiles so they actually work
with the v4 changes
-Tweak some formatting, spacing, and comments
-Fix validation of charge_type so illegal values
can't be set. Before negative error codes were
accidentally getting casted to positive numbers
-Remove more unneeded parentheses.
v4 changes:
-Use put_unaligned_le32() to store PID in request.
-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

.../ABI/testing/sysfs-class-power-wilco | 30 +++
drivers/platform/chrome/wilco_ec/core.c | 13 ++
drivers/power/supply/Kconfig | 9 +
drivers/power/supply/Makefile | 1 +
drivers/power/supply/wilco-charger.c | 187 ++++++++++++++++++
include/linux/platform_data/wilco-ec.h | 2 +
6 files changed, 242 insertions(+)
create mode 100644 Documentation/ABI/testing/sysfs-class-power-wilco
create mode 100644 drivers/power/supply/wilco-charger.c

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/core.c b/drivers/platform/chrome/wilco_ec/core.c
index 05e1e2be1c91..a8e3ef59f4ea 100644
--- a/drivers/platform/chrome/wilco_ec/core.c
+++ b/drivers/platform/chrome/wilco_ec/core.c
@@ -89,8 +89,20 @@ static int wilco_ec_probe(struct platform_device *pdev)
goto unregister_debugfs;
}

+ /* Register child device to be found by charger config driver. */
+ ec->charger_pdev = platform_device_register_data(dev, "wilco-charger",
+ PLATFORM_DEVID_AUTO,
+ NULL, 0);
+ if (IS_ERR(ec->charger_pdev)) {
+ dev_err(dev, "Failed to create charger platform device\n");
+ ret = PTR_ERR(ec->charger_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 +114,7 @@ static int wilco_ec_remove(struct platform_device *pdev)
{
struct wilco_ec_device *ec = platform_get_drvdata(pdev);

+ platform_device_unregister(ec->charger_pdev);
platform_device_unregister(ec->rtc_pdev);
if (ec->debugfs_pdev)
platform_device_unregister(ec->debugfs_pdev);
diff --git a/drivers/power/supply/Kconfig b/drivers/power/supply/Kconfig
index e901b9879e7e..a958b17b9c9d 100644
--- a/drivers/power/supply/Kconfig
+++ b/drivers/power/supply/Kconfig
@@ -660,4 +660,13 @@ config FUEL_GAUGE_SC27XX
Say Y here to enable support for fuel gauge with SC27XX
PMIC chips.

+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
diff --git a/drivers/power/supply/Makefile b/drivers/power/supply/Makefile
index b731c2a9b695..2b603a142701 100644
--- a/drivers/power/supply/Makefile
+++ b/drivers/power/supply/Makefile
@@ -87,3 +87,4 @@ obj-$(CONFIG_AXP288_CHARGER) += axp288_charger.o
obj-$(CONFIG_CHARGER_CROS_USBPD) += cros_usbpd-charger.o
obj-$(CONFIG_CHARGER_SC2731) += sc2731_charger.o
obj-$(CONFIG_FUEL_GAUGE_SC27XX) += sc27xx_fuel_gauge.o
+obj-$(CONFIG_CHARGER_WILCO) += wilco-charger.o
diff --git a/drivers/power/supply/wilco-charger.c b/drivers/power/supply/wilco-charger.c
new file mode 100644
index 000000000000..7ed78c9fd828
--- /dev/null
+++ b/drivers/power/supply/wilco-charger.c
@@ -0,0 +1,187 @@
+// 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 = "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);
+
+ 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@xxxxxxxxxxxx>");
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Wilco EC charge control driver");
diff --git a/include/linux/platform_data/wilco-ec.h b/include/linux/platform_data/wilco-ec.h
index 50a21bd5fd44..66d9f177bec2 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.
+ * @charger_pdev: Child platform_device used by the charger 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 *charger_pdev;
};

/**
--
2.20.1