Introduce Embedded Controller driver for Acer A500

Add binding document for the ENE KB930 Embedded Controller.

Reviewed-by Rob Herring <[email protected]>

Signed-off-by Dmitry Osipenko <[email protected]>

---
 .../devicetree/bindings/mfd/ene-kb930.yaml    | 65 +++++++++++++++++++
 1 file changed, 65 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/mfd/ene-kb930.yaml

Acer Iconia Tab A500 is an Android tablet device, it has ENE KB930 Embedded Controller which provides battery-gauge, LED, GPIO and some other functions. The EC uses firmware that is specifically customized for Acer A500. This patch adds MFD driver for the Embedded Controller which allows to power-off / reboot the A500 device, it also provides a common register read/write API that will be used by the sub-devices.

Signed-off-by Dmitry Osipenko <[email protected]>

---
 drivers/mfd/Kconfig        |  11 ++
 drivers/mfd/Makefile       |   1 +
 drivers/mfd/acer-ec-a500.c | 202 +++++++++++++++++++++++++++++++++++++
 3 files changed, 214 insertions(+)
 create mode 100644 drivers/mfd/acer-ec-a500.c

Quoted 8 lines

Acer Iconia Tab A500 is an Android tablet device, it has ENE KB930 Embedded Controller which provides battery-gauge, LED, GPIO and some other functions. The EC uses firmware that is specifically customized for Acer A500. This patch adds MFD driver for the Embedded Controller which allows to power-off / reboot the A500 device, it also provides a common register read/write API that will be used by the sub-devices.

Quoted 7 lines

Signed-off-by Dmitry Osipenko <[email protected]>

---
 drivers/mfd/Kconfig        |  11 ++
 drivers/mfd/Makefile       |   1 +
 drivers/mfd/acer-ec-a500.c | 202 +++++++++++++++++++++++++++++++++++++
 3 files changed, 214 insertions(+)
 create mode 100644 drivers/mfd/acer-ec-a500.c

Looks good to me:

For my own reference (apply this as-is to your sign-off block):

Acked-for-MFD-by Lee Jones <[email protected]>

Do you have a merge plan?

Acer Iconia Tab A500 is an Android tablet device, it has ENE KB930 Embedded Controller which provides battery-gauge, LED, GPIO and some other functions. The EC uses firmware that is specifically customized for Acer A500. This patch adds MFD driver for the Embedded Controller which allows to power-off / reboot the A500 device, it also provides a common register read/write API that will be used by the sub-devices.

Signed-off-by Dmitry Osipenko <[email protected]>

---
 drivers/mfd/Kconfig        |  11 ++
 drivers/mfd/Makefile       |   1 +
 drivers/mfd/acer-ec-a500.c | 202 +++++++++++++++++++++++++++++++++++++
 3 files changed, 214 insertions(+)
 create mode 100644 drivers/mfd/acer-ec-a500.c

This patch adds battery gauge driver for Acer Iconia Tab A500 device. The battery gauge function is provided via the Embedded Controller, which is found on the Acer A500.

Reviewed-by Sebastian Reichel <[email protected]>

Signed-off-by Dmitry Osipenko <[email protected]>

---

 drivers/power/supply/Kconfig             |   6 +
 drivers/power/supply/Makefile            |   1 +
 drivers/power/supply/acer_a500_battery.c | 297 +++++++++++++++++++++++
 3 files changed, 304 insertions(+)
 create mode 100644 drivers/power/supply/acer_a500_battery.c

drivers/power/supply/Kconfig +6 -0

index eec646c568b7..bc493173ddbc 100644
@@ -774,4 +774,10 @@ config RN5T618_POWER
 	  This driver can also be built as a module. If so, the module will be
 	  called rn5t618_power.
 
+config BATTERY_ACER_A500
+	tristate "Acer Iconia Tab A500 battery driver"
+	depends on MFD_ACER_A500_EC
+	help
+	  Say Y to include support for Acer Iconia Tab A500 battery fuel gauge.
+
 endif # POWER_SUPPLY

drivers/power/supply/Makefile +1 -0

index dd4b86318cd9..0607a3d64c0f 100644
@@ -98,3 +98,4 @@ obj-$(CONFIG_CHARGER_BD70528)	+= bd70528-charger.o
 obj-$(CONFIG_CHARGER_BD99954)	+= bd99954-charger.o
 obj-$(CONFIG_CHARGER_WILCO)	+= wilco-charger.o
 obj-$(CONFIG_RN5T618_POWER)	+= rn5t618_power.o
+obj-$(CONFIG_BATTERY_ACER_A500)	+= acer_a500_battery.o

drivers/power/supply/acer_a500_battery.c new file +297 -0

new file mode 100644
index 000000000000..32a0bfcac08f
@@ -0,0 +1,297 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Battery driver for Acer Iconia Tab A500.
+ *
+ * Copyright 2020 GRATE-driver project.
+ *
+ * Based on downstream driver from Acer Inc.
+ * Based on NVIDIA Gas Gauge driver for SBS Compliant Batteries.
+ *
+ * Copyright (c) 2010, NVIDIA Corporation.
+ */
+
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/power_supply.h>
+#include <linux/regmap.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/workqueue.h>
+
+enum {
+	REG_CAPACITY,
+	REG_VOLTAGE,
+	REG_CURRENT,
+	REG_DESIGN_CAPACITY,
+	REG_TEMPERATURE,
+};
+
+#define EC_DATA(_reg, _psp) {			\
+	.psp = POWER_SUPPLY_PROP_ ## _psp,	\
+	.reg = _reg,				\
+}
+
+static const struct battery_register {
+	enum power_supply_property psp;
+	unsigned int reg;
+} ec_data[] = {
+	[REG_CAPACITY]		= EC_DATA(0x00, CAPACITY),
+	[REG_VOLTAGE]		= EC_DATA(0x01, VOLTAGE_NOW),
+	[REG_CURRENT]		= EC_DATA(0x03, CURRENT_NOW),
+	[REG_DESIGN_CAPACITY]	= EC_DATA(0x08, CHARGE_FULL_DESIGN),
+	[REG_TEMPERATURE]	= EC_DATA(0x0a, TEMP),
+};
+
+static const enum power_supply_property a500_battery_properties[] = {
+	POWER_SUPPLY_PROP_CAPACITY,
+	POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN,
+	POWER_SUPPLY_PROP_CURRENT_NOW,
+	POWER_SUPPLY_PROP_PRESENT,
+	POWER_SUPPLY_PROP_STATUS,
+	POWER_SUPPLY_PROP_TECHNOLOGY,
+	POWER_SUPPLY_PROP_TEMP,
+	POWER_SUPPLY_PROP_VOLTAGE_NOW,
+};
+
+struct a500_battery {
+	struct delayed_work poll_work;
+	struct power_supply *psy;
+	struct regmap *regmap;
+	unsigned int capacity;
+};
+
+static bool a500_battery_update_capacity(struct a500_battery *bat)
+{
+	unsigned int capacity;
+	int err;
+
+	err = regmap_read(bat->regmap, ec_data[REG_CAPACITY].reg, &capacity);
+	if (err)
+		return false;
+
+	/* capacity can be >100% even if max value is 100% */
+	capacity = min(capacity, 100u);
+
+	if (bat->capacity != capacity) {
+		bat->capacity = capacity;
+		return true;
+	}
+
+	return false;
+}
+
+static int a500_battery_get_status(struct a500_battery *bat)
+{
+	if (bat->capacity < 100) {
+		if (power_supply_am_i_supplied(bat->psy))
+			return POWER_SUPPLY_STATUS_CHARGING;
+		else
+			return POWER_SUPPLY_STATUS_DISCHARGING;
+	}
+
+	return POWER_SUPPLY_STATUS_FULL;
+}
+
+static void a500_battery_unit_adjustment(struct device *dev,
+					 enum power_supply_property psp,
+					 union power_supply_propval *val)
+{
+	const unsigned int base_unit_conversion = 1000;
+	const unsigned int temp_kelvin_to_celsius = 2731;
+
+	switch (psp) {
+	case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
+	case POWER_SUPPLY_PROP_CURRENT_NOW:
+	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
+		val->intval *= base_unit_conversion;
+		break;
+
+	case POWER_SUPPLY_PROP_TEMP:
+		val->intval -= temp_kelvin_to_celsius;
+		break;
+
+	case POWER_SUPPLY_PROP_PRESENT:
+		val->intval = !!val->intval;
+		break;
+
+	default:
+		dev_dbg(dev,
+			"%s: no need for unit conversion %d\n", __func__, psp);
+	}
+}
+
+static int a500_battery_get_ec_data_index(struct device *dev,
+					  enum power_supply_property psp)
+{
+	unsigned int i;
+
+	/*
+	 * DESIGN_CAPACITY register always returns a non-zero value if
+	 * battery is connected and zero if disconnected, hence we'll use
+	 * it for judging the battery presence.
+	 */
+	if (psp == POWER_SUPPLY_PROP_PRESENT)
+		psp = POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN;
+
+	for (i = 0; i < ARRAY_SIZE(ec_data); i++)
+		if (psp == ec_data[i].psp)
+			return i;
+
+	dev_dbg(dev, "%s: invalid property %u\n", __func__, psp);
+
+	return -EINVAL;
+}
+
+static int a500_battery_get_property(struct power_supply *psy,
+				     enum power_supply_property psp,
+				     union power_supply_propval *val)
+{
+	struct a500_battery *bat = power_supply_get_drvdata(psy);
+	struct device *dev = psy->dev.parent;
+	int ret = 0;
+
+	switch (psp) {
+	case POWER_SUPPLY_PROP_STATUS:
+		val->intval = a500_battery_get_status(bat);
+		break;
+
+	case POWER_SUPPLY_PROP_TECHNOLOGY:
+		val->intval = POWER_SUPPLY_TECHNOLOGY_LION;
+		break;
+
+	case POWER_SUPPLY_PROP_CAPACITY:
+		a500_battery_update_capacity(bat);
+		val->intval = bat->capacity;
+		break;
+
+	case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
+	case POWER_SUPPLY_PROP_CURRENT_NOW:
+	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
+	case POWER_SUPPLY_PROP_PRESENT:
+	case POWER_SUPPLY_PROP_TEMP:
+		ret = a500_battery_get_ec_data_index(dev, psp);
+		if (ret < 0)
+			break;
+
+		ret = regmap_read(bat->regmap, ec_data[ret].reg, &val->intval);
+		break;
+
+	default:
+		dev_err(dev, "%s: invalid property %u\n", __func__, psp);
+		return -EINVAL;
+	}
+
+	if (!ret) {
+		/* convert units to match requirements of power supply class */
+		a500_battery_unit_adjustment(dev, psp, val);
+	}
+
+	dev_dbg(dev, "%s: property = %d, value = %x\n",
+		__func__, psp, val->intval);
+
+	/* return NODATA for properties if battery not presents */
+	if (ret)
+		return -ENODATA;
+
+	return 0;
+}
+
+static void a500_battery_poll_work(struct work_struct *work)
+{
+	struct a500_battery *bat;
+	bool capacity_changed;
+
+	bat = container_of(work, struct a500_battery, poll_work.work);
+	capacity_changed = a500_battery_update_capacity(bat);
+
+	if (capacity_changed)
+		power_supply_changed(bat->psy);
+
+	/* continuously send uevent notification */
+	schedule_delayed_work(&bat->poll_work, 30 * HZ);
+}
+
+static const struct power_supply_desc a500_battery_desc = {
+	.name = "ec-battery",
+	.type = POWER_SUPPLY_TYPE_BATTERY,
+	.properties = a500_battery_properties,
+	.get_property = a500_battery_get_property,
+	.num_properties = ARRAY_SIZE(a500_battery_properties),
+	.external_power_changed = power_supply_changed,
+};
+
+static int a500_battery_probe(struct platform_device *pdev)
+{
+	struct power_supply_config psy_cfg = {};
+	struct a500_battery *bat;
+
+	bat = devm_kzalloc(&pdev->dev, sizeof(*bat), GFP_KERNEL);
+	if (!bat)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, bat);
+
+	psy_cfg.of_node = pdev->dev.parent->of_node;
+	psy_cfg.drv_data = bat;
+
+	bat->regmap = dev_get_regmap(pdev->dev.parent, "KB930");
+	if (!bat->regmap)
+		return -EINVAL;
+
+	bat->psy = devm_power_supply_register_no_ws(&pdev->dev,
+						    &a500_battery_desc,
+						    &psy_cfg);
+	if (IS_ERR(bat->psy))
+		return dev_err_probe(&pdev->dev, PTR_ERR(bat->psy),
+				     "failed to register battery\n");
+
+	INIT_DELAYED_WORK(&bat->poll_work, a500_battery_poll_work);
+	schedule_delayed_work(&bat->poll_work, HZ);
+
+	return 0;
+}
+
+static int a500_battery_remove(struct platform_device *pdev)
+{
+	struct a500_battery *bat = dev_get_drvdata(&pdev->dev);
+
+	cancel_delayed_work_sync(&bat->poll_work);
+
+	return 0;
+}
+
+static int __maybe_unused a500_battery_suspend(struct device *dev)
+{
+	struct a500_battery *bat = dev_get_drvdata(dev);
+
+	cancel_delayed_work_sync(&bat->poll_work);
+
+	return 0;
+}
+
+static int __maybe_unused a500_battery_resume(struct device *dev)
+{
+	struct a500_battery *bat = dev_get_drvdata(dev);
+
+	schedule_delayed_work(&bat->poll_work, HZ);
+
+	return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(a500_battery_pm_ops,
+			 a500_battery_suspend, a500_battery_resume);
+
+static struct platform_driver a500_battery_driver = {
+	.driver = {
+		.name = "acer-a500-iconia-battery",
+		.pm = &a500_battery_pm_ops,
+	},
+	.probe = a500_battery_probe,
+	.remove = a500_battery_remove,
+};
+module_platform_driver(a500_battery_driver);
+
+MODULE_DESCRIPTION("Battery gauge driver for Acer Iconia Tab A500");
+MODULE_AUTHOR("Dmitry Osipenko <[email protected]>");
+MODULE_ALIAS("platform:acer-a500-iconia-battery");
+MODULE_LICENSE("GPL");

Signature · 1 line

2.29.2

This series adds support for the Embedded Controller which is found on Acer Iconia Tab A500 (Android tablet device).

The Embedded Controller is ENE KB930 and it's running firmware customized for the A500. The firmware interface may be reused by some other sibling Acer tablets, although none of those tablets are supported in upstream yet.

Changelog:

v8: - This series partially missed v5.11 kernel release, hence resending

      for v5.12.