[PATCH 14/15] power: supply: Add driver for Cherry Trail Whiskey Cove PMIC Fuel Gauge

[Hans de Goede <hdegoede@redhat.com>]

Add a driver for the Cherry Trail Whiskey Cove PMIC Fuel Gauge, note
the Cherry Trail Whiskey Cove PMIC Fuel Gauge block is purely a fuel gauge
and not a full battery controller. As such it offers a platform_data
callback for extra power_supply properties for the actual external-charger
ic driver and does not register a power_supply itself.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/power/supply/Kconfig             |   9 ++
 drivers/power/supply/Makefile            |   1 +
 drivers/power/supply/cht_wc_fuel_gauge.c | 209 +++++++++++++++++++++++++++++++
 include/linux/power/cht_wc_fuel_gauge.h  |  21 ++++
 4 files changed, 240 insertions(+)
 create mode 100644 drivers/power/supply/cht_wc_fuel_gauge.c
 create mode 100644 include/linux/power/cht_wc_fuel_gauge.h

diff --git a/drivers/power/supply/Kconfig b/drivers/power/supply/Kconfig
index fd93110..34ebfca 100644
--- a/drivers/power/supply/Kconfig
+++ b/drivers/power/supply/Kconfig
@@ -538,4 +538,13 @@ config AXP20X_POWER
 	  This driver provides support for the power supply features of
 	  AXP20x PMIC.
 
+config CHT_WC_FUEL_GAUGE
+	tristate "Intel Cherry Trail Whiskey Cove PMIC Fuel Gauge"
+	depends on INTEL_SOC_PMIC_CHTWC
+	help
+	  This adds support for the battery fuel gauge found in the Intel
+	  Cherry Trail Whiskey Cove PMIC. This driver allows monitoring
+	  of the charge level of the battery on Intel Cherry Trail systems
+	  with a Whiskey Cove PMIC.
+
 endif # POWER_SUPPLY
diff --git a/drivers/power/supply/Makefile b/drivers/power/supply/Makefile
index 3789a2c..702e28a 100644
--- a/drivers/power/supply/Makefile
+++ b/drivers/power/supply/Makefile
@@ -74,3 +74,4 @@ obj-$(CONFIG_CHARGER_TPS65090)	+= tps65090-charger.o
 obj-$(CONFIG_CHARGER_TPS65217)	+= tps65217_charger.o
 obj-$(CONFIG_AXP288_FUEL_GAUGE) += axp288_fuel_gauge.o
 obj-$(CONFIG_AXP288_CHARGER)	+= axp288_charger.o
+obj-$(CONFIG_CHT_WC_FUEL_GAUGE)	+= cht_wc_fuel_gauge.o
diff --git a/drivers/power/supply/cht_wc_fuel_gauge.c b/drivers/power/supply/cht_wc_fuel_gauge.c
new file mode 100644
index 0000000..56f6e5a
--- /dev/null
+++ b/drivers/power/supply/cht_wc_fuel_gauge.c
@@ -0,0 +1,209 @@
+/*
+ * Intel CHT Whiskey Cove Fuel Gauge driver
+ * Copyright (C) 2017 Hans de Goede <hdegoede@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version
+ * 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * Cherrytrail Whiskey Cove devices have 2 functional blocks which interact
+ * with the battery.
+ *
+ * 1) The fuel-gauge which is build into the Whiskey Cove PMIC, but has its
+ * own i2c bus and i2c client addresses separately from the rest of the PMIC.
+ * That block is what this driver is for.
+ *
+ * 2) An external charger IC, which is connected to the SMBUS controller
+ * which is part of the rest of the Whiskey Cove PMIC, mfd/intel_cht_wc.c
+ * registers a platform device for the SMBUS controller and
+ * i2c/busses/i2c-cht-wc.c contains the i2c-adapter driver for this.
+ *
+ * However we want to present this as a single power_supply device to
+ * userspace. So this driver offers a callback to get the fuel-gauge
+ * power_supply properties, which gets passed to the external charger
+ * driver via i2c_board_info when i2c-cht-wc.c calls i2c_new_device().
+ */
+
+#include <linux/acpi.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/mfd/intel_soc_pmic.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/power_supply.h>
+#include <linux/power/cht_wc_fuel_gauge.h>
+#include <linux/slab.h>
+
+#define REG_CHARGE_NOW		0x05
+#define REG_VOLTAGE_NOW		0x09
+#define REG_CURRENT_NOW		0x0a
+#define REG_CURRENT_AVG		0x0b
+#define REG_CHARGE_FULL		0x10
+#define REG_CHARGE_DESIGN	0x18
+#define REG_VOLTAGE_AVG		0x19
+#define REG_VOLTAGE_OCV		0x1b /* Only updated during charging */
+
+#define CHT_WC_FG_PTYPE		4
+
+struct cht_wc_fg_data {
+	struct device *dev;
+	struct i2c_client *client;
+};
+
+static DEFINE_MUTEX(cht_wc_fg_mutex);
+static struct cht_wc_fg_data *cht_wc_fg;
+
+static int cht_wc_fg_read(struct cht_wc_fg_data *fg, u8 reg,
+			  union power_supply_propval *val, int scale,
+			  int sign_extend)
+{
+	int ret;
+
+	ret = i2c_smbus_read_word_data(fg->client, reg);
+	if (ret < 0)
+		return ret;
+
+	if (sign_extend)
+		ret = sign_extend32(ret, 15);
+
+	val->intval = ret * scale;
+
+	return 0;
+}
+
+int cht_wc_fg_get_property(enum power_supply_property prop,
+			   union power_supply_propval *val)
+{
+	int ret = 0;
+
+	mutex_lock(&cht_wc_fg_mutex);
+
+	if (!cht_wc_fg) {
+		ret = -ENXIO;
+		goto out_unlock;
+	}
+
+	switch (prop) {
+	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
+		ret = cht_wc_fg_read(cht_wc_fg, REG_VOLTAGE_NOW, val, 75, 0);
+		break;
+	case POWER_SUPPLY_PROP_VOLTAGE_AVG:
+		ret = cht_wc_fg_read(cht_wc_fg, REG_VOLTAGE_AVG, val, 75, 0);
+		break;
+	case POWER_SUPPLY_PROP_VOLTAGE_OCV:
+		ret = cht_wc_fg_read(cht_wc_fg, REG_VOLTAGE_OCV, val, 75, 0);
+		break;
+	case POWER_SUPPLY_PROP_CURRENT_NOW:
+		ret = cht_wc_fg_read(cht_wc_fg, REG_CURRENT_NOW, val, 150, 1);
+		break;
+	case POWER_SUPPLY_PROP_CURRENT_AVG:
+		ret = cht_wc_fg_read(cht_wc_fg, REG_CURRENT_AVG, val, 150, 1);
+		break;
+	case POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN:
+		ret = cht_wc_fg_read(cht_wc_fg, REG_CHARGE_DESIGN, val, 500, 0);
+		break;
+	case POWER_SUPPLY_PROP_CHARGE_FULL:
+		ret = cht_wc_fg_read(cht_wc_fg, REG_CHARGE_FULL, val, 500, 0);
+		break;
+	case POWER_SUPPLY_PROP_CHARGE_NOW:
+		ret = cht_wc_fg_read(cht_wc_fg, REG_CHARGE_NOW, val, 500, 0);
+		break;
+	default:
+		ret = -ENODATA;
+	}
+out_unlock:
+	mutex_unlock(&cht_wc_fg_mutex);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(cht_wc_fg_get_property);
+
+static int cht_wc_fg_probe(struct i2c_client *client,
+			const struct i2c_device_id *i2c_id)
+{
+	struct device *dev = &client->dev;
+	struct cht_wc_fg_data *fg;
+	acpi_status status;
+	unsigned long long ptyp;
+
+	fg = devm_kzalloc(dev, sizeof(*fg), GFP_KERNEL);
+	if (!fg)
+		return -ENOMEM;
+
+	status = acpi_evaluate_integer(ACPI_HANDLE(dev), "PTYP", NULL, &ptyp);
+	if (ACPI_FAILURE(status)) {
+		dev_err(dev, "Failed to get PTYPE\n");
+		return -ENODEV;
+	}
+
+	/*
+	 * The same ACPI HID is used with different PMICs check PTYP to
+	 * ensure that we are dealing with a Whiskey Cove PMIC.
+	 */
+	if (ptyp != CHT_WC_FG_PTYPE)
+		return -ENODEV;
+
+	fg->dev = dev;
+	/*
+	 * The current resource settings table for the fuel gauge contains
+	 * multiple i2c devices on 2 different i2c-busses. The one we actually
+	 * want is the second resource (index 1).
+	 */
+	fg->client = i2c_acpi_new_device(dev, 1);
+	if (!fg->client)
+		return -EPROBE_DEFER;
+
+	i2c_set_clientdata(client, fg);
+
+	mutex_lock(&cht_wc_fg_mutex);
+	cht_wc_fg = fg;
+	mutex_unlock(&cht_wc_fg_mutex);
+
+	return 0;
+}
+
+static int cht_wc_fg_remove(struct i2c_client *i2c)
+{
+	struct cht_wc_fg_data *fg = i2c_get_clientdata(i2c);
+
+	mutex_lock(&cht_wc_fg_mutex);
+	cht_wc_fg = NULL;
+	mutex_unlock(&cht_wc_fg_mutex);
+
+	i2c_unregister_device(fg->client);
+
+	return 0;
+}
+
+static const struct i2c_device_id cht_wc_fg_i2c_id[] = {
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, cht_wc_fg_i2c_id);
+
+static const struct acpi_device_id cht_wc_fg_acpi_ids[] = {
+	{ "INT33FE", },
+	{ }
+};
+MODULE_DEVICE_TABLE(acpi, cht_wc_fg_acpi_ids);
+
+static struct i2c_driver cht_wc_fg_driver = {
+	.driver	= {
+		.name	= "CHT Whiskey Cove PMIC Fuel Gauge",
+		.acpi_match_table = ACPI_PTR(cht_wc_fg_acpi_ids),
+	},
+	.probe = cht_wc_fg_probe,
+	.remove = cht_wc_fg_remove,
+	.id_table = cht_wc_fg_i2c_id,
+	.irq_index = 1,
+};
+
+module_i2c_driver(cht_wc_fg_driver);
+
+MODULE_DESCRIPTION("Intel CHT Whiskey Cove PMIC Fuel Gauge driver");
+MODULE_AUTHOR("Hans de Goede <hdegoede@redhat.com>");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/power/cht_wc_fuel_gauge.h b/include/linux/power/cht_wc_fuel_gauge.h
new file mode 100644
index 0000000..4b4e051
--- /dev/null
+++ b/include/linux/power/cht_wc_fuel_gauge.h
@@ -0,0 +1,21 @@
+/*
+ * Intel CHT Whiskey Cove Fuel Gauge driver
+ * Copyright (C) 2017 Hans de Goede <hdegoede@redhat.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License version
+ * 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef __CHT_WC_FUEL_GAUGE_H
+#define __CHT_WC_FUEL_GAUGE_H
+
+int cht_wc_fg_get_property(enum power_supply_property prop,
+			   union power_supply_propval *val);
+
+#endif
-- 
2.9.3