power: supply: Add support for MAX14656 USB charger detector

The MAX14656 USB charger detector, also known as "AL32" is used to detect
the presence and capabilities of attached USB chargers. The device is
attached via I2C plus one interrupt line to signalize events.

The device can be found in LG smartphones like LS665 and LS770, compatible
devices are present in 4th/5th generation Amazon Kindle readers referenced
in source code packages as "Maxim AL32".

The initial version of this driver has been extracted from LG source code
package LGLS665_Android_Lollipop_LS665ZV3, enriched with information from
the Kindle_src_4.1.3 source code package and adapted to the current power
class sysfs interface. Non-Standard Apple chargers which the device may
detect are mapped to the USB Battery Charging Specification Revision 1.2
class USB_DCP.

Signed-off-by: Alexander Kurz <akurz@blala.de>
Signed-off-by: Sebastian Reichel <sre@kernel.org>

drivers/power/supply/Kconfig

@@ -369,6 +369,16 @@ config CHARGER_MAX14577
 	  Say Y to enable support for the battery charger control sysfs and
 	  platform data of MAX14577/77836 MUICs.
 
+config CHARGER_DETECTOR_MAX14656
+	tristate "Maxim MAX14656 USB charger detector"
+	depends on I2C
+	depends on OF
+	help
+	  Say Y to enable support for the Maxim MAX14656 USB charger detector.
+	  The device is compliant with the USB Battery Charging Specification
+	  Revision 1.2 and can be found e.g. in Kindle 4/5th generation
+	  readers and certain LG devices.
+
 config CHARGER_MAX77693
 	tristate "Maxim MAX77693 battery charger driver"
 	depends on MFD_MAX77693

drivers/power/supply/Makefile

@@ -58,6 +58,7 @@ obj-$(CONFIG_CHARGER_LP8788)	+= lp8788-charger.o
 obj-$(CONFIG_CHARGER_GPIO)	+= gpio-charger.o
 obj-$(CONFIG_CHARGER_MANAGER)	+= charger-manager.o
 obj-$(CONFIG_CHARGER_MAX14577)	+= max14577_charger.o
+obj-$(CONFIG_CHARGER_DETECTOR_MAX14656)	+= max14656_charger_detector.o
 obj-$(CONFIG_CHARGER_MAX77693)	+= max77693_charger.o
 obj-$(CONFIG_CHARGER_MAX8997)	+= max8997_charger.o
 obj-$(CONFIG_CHARGER_MAX8998)	+= max8998_charger.o

drivers/power/supply/max14656_charger_detector.c

@@ -0,0 +1,326 @@
+/*
+ * Maxim MAX14656 / AL32 USB Charger Detector driver
+ *
+ * Copyright (C) 2014 LG Electronics, Inc
+ * Copyright (C) 2016 Alexander Kurz <akurz@blala.de>
+ *
+ * Components from Maxim AL32 Charger detection Driver for MX50 Yoshi Board
+ * Copyright (C) Amazon Technologies Inc. All rights reserved.
+ * Manish Lachwani (lachwani@lab126.com)
+ *
+ * This package is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 and
+ * only version 2 as published by the Free Software Foundation.
+ *
+ */
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/slab.h>
+#include <linux/gpio.h>
+#include <linux/of_gpio.h>
+#include <linux/of_device.h>
+#include <linux/workqueue.h>
+#include <linux/power_supply.h>
+
+#define MAX14656_MANUFACTURER	"Maxim Integrated"
+#define MAX14656_NAME		"max14656"
+
+#define MAX14656_DEVICE_ID	0x00
+#define MAX14656_INTERRUPT_1	0x01
+#define MAX14656_INTERRUPT_2	0x02
+#define MAX14656_STATUS_1	0x03
+#define MAX14656_STATUS_2	0x04
+#define MAX14656_INTMASK_1	0x05
+#define MAX14656_INTMASK_2	0x06
+#define MAX14656_CONTROL_1	0x07
+#define MAX14656_CONTROL_2	0x08
+#define MAX14656_CONTROL_3	0x09
+
+#define DEVICE_VENDOR_MASK	0xf0
+#define DEVICE_REV_MASK		0x0f
+#define INT_EN_REG_MASK		BIT(4)
+#define CHG_TYPE_INT_MASK	BIT(0)
+#define STATUS1_VB_VALID_MASK	BIT(4)
+#define STATUS1_CHG_TYPE_MASK	0xf
+#define INT1_DCD_TIMEOUT_MASK	BIT(7)
+#define CONTROL1_DEFAULT	0x0d
+#define CONTROL1_INT_EN		BIT(4)
+#define CONTROL1_INT_ACTIVE_HIGH	BIT(5)
+#define CONTROL1_EDGE		BIT(7)
+#define CONTROL2_DEFAULT	0x8e
+#define CONTROL2_ADC_EN		BIT(0)
+#define CONTROL3_DEFAULT	0x8d
+
+enum max14656_chg_type {
+	MAX14656_NO_CHARGER	= 0,
+	MAX14656_SDP_CHARGER,
+	MAX14656_CDP_CHARGER,
+	MAX14656_DCP_CHARGER,
+	MAX14656_APPLE_500MA_CHARGER,
+	MAX14656_APPLE_1A_CHARGER,
+	MAX14656_APPLE_2A_CHARGER,
+	MAX14656_SPECIAL_500MA_CHARGER,
+	MAX14656_APPLE_12W,
+	MAX14656_CHARGER_LAST
+};
+
+static const struct max14656_chg_type_props {
+	enum power_supply_type type;
+} chg_type_props[] = {
+	{ POWER_SUPPLY_TYPE_UNKNOWN },
+	{ POWER_SUPPLY_TYPE_USB },
+	{ POWER_SUPPLY_TYPE_USB_CDP },
+	{ POWER_SUPPLY_TYPE_USB_DCP },
+	{ POWER_SUPPLY_TYPE_USB_DCP },
+	{ POWER_SUPPLY_TYPE_USB_DCP },
+	{ POWER_SUPPLY_TYPE_USB_DCP },
+	{ POWER_SUPPLY_TYPE_USB_DCP },
+	{ POWER_SUPPLY_TYPE_USB },
+};
+
+struct max14656_chip {
+	struct i2c_client	*client;
+	struct power_supply	*detect_psy;
+	struct power_supply_desc psy_desc;
+	struct delayed_work	irq_work;
+
+	int irq;
+	int online;
+};
+
+static int max14656_read_reg(struct i2c_client *client, int reg, u8 *val)
+{
+	s32 ret;
+
+	ret = i2c_smbus_read_byte_data(client, reg);
+	if (ret < 0) {
+		dev_err(&client->dev,
+			"i2c read fail: can't read from %02x: %d\n",
+			reg, ret);
+		return ret;
+	}
+	*val = ret;
+	return 0;
+}
+
+static int max14656_write_reg(struct i2c_client *client, int reg, u8 val)
+{
+	s32 ret;
+
+	ret = i2c_smbus_write_byte_data(client, reg, val);
+	if (ret < 0) {
+		dev_err(&client->dev,
+			"i2c write fail: can't write %02x to %02x: %d\n",
+			val, reg, ret);
+		return ret;
+	}
+	return 0;
+}
+
+static int max14656_read_block_reg(struct i2c_client *client, u8 reg,
+				  u8 length, u8 *val)
+{
+	int ret;
+
+	ret = i2c_smbus_read_i2c_block_data(client, reg, length, val);
+	if (ret < 0) {
+		dev_err(&client->dev, "failed to block read reg 0x%x: %d\n",
+				reg, ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+#define        REG_TOTAL_NUM   5
+static void max14656_irq_worker(struct work_struct *work)
+{
+	struct max14656_chip *chip =
+		container_of(work, struct max14656_chip, irq_work.work);
+
+	u8 buf[REG_TOTAL_NUM];
+	u8 chg_type;
+	int ret = 0;
+
+	ret = max14656_read_block_reg(chip->client, MAX14656_DEVICE_ID,
+				      REG_TOTAL_NUM, buf);
+
+	if ((buf[MAX14656_STATUS_1] & STATUS1_VB_VALID_MASK) &&
+		(buf[MAX14656_STATUS_1] & STATUS1_CHG_TYPE_MASK)) {
+		chg_type = buf[MAX14656_STATUS_1] & STATUS1_CHG_TYPE_MASK;
+		if (chg_type < MAX14656_CHARGER_LAST)
+			chip->psy_desc.type = chg_type_props[chg_type].type;
+		else
+			chip->psy_desc.type = POWER_SUPPLY_TYPE_UNKNOWN;
+		chip->online = 1;
+	} else {
+		chip->online = 0;
+		chip->psy_desc.type = POWER_SUPPLY_TYPE_UNKNOWN;
+	}
+
+	power_supply_changed(chip->detect_psy);
+}
+
+static irqreturn_t max14656_irq(int irq, void *dev_id)
+{
+	struct max14656_chip *chip = dev_id;
+
+	schedule_delayed_work(&chip->irq_work, msecs_to_jiffies(100));
+
+	return IRQ_HANDLED;
+}
+
+static int max14656_hw_init(struct max14656_chip *chip)
+{
+	uint8_t val = 0;
+	uint8_t rev;
+	struct i2c_client *client = chip->client;
+
+	if (max14656_read_reg(client, MAX14656_DEVICE_ID, &val))
+		return -ENODEV;
+
+	if ((val & DEVICE_VENDOR_MASK) != 0x20) {
+		dev_err(&client->dev, "wrong vendor ID %d\n",
+			((val & DEVICE_VENDOR_MASK) >> 4));
+		return -ENODEV;
+	}
+	rev = val & DEVICE_REV_MASK;
+
+	/* Turn on ADC_EN */
+	if (max14656_write_reg(client, MAX14656_CONTROL_2, CONTROL2_ADC_EN))
+		return -EINVAL;
+
+	/* turn on interrupts and low power mode */
+	if (max14656_write_reg(client, MAX14656_CONTROL_1,
+		CONTROL1_DEFAULT |
+		CONTROL1_INT_EN |
+		CONTROL1_INT_ACTIVE_HIGH |
+		CONTROL1_EDGE))
+		return -EINVAL;
+
+	if (max14656_write_reg(client, MAX14656_INTMASK_1, 0x3))
+		return -EINVAL;
+
+	if (max14656_write_reg(client, MAX14656_INTMASK_2, 0x1))
+		return -EINVAL;
+
+	dev_info(&client->dev, "detected revision %d\n", rev);
+	return 0;
+}
+
+static int max14656_get_property(struct power_supply *psy,
+			    enum power_supply_property psp,
+			    union power_supply_propval *val)
+{
+	struct max14656_chip *chip = power_supply_get_drvdata(psy);
+
+	switch (psp) {
+	case POWER_SUPPLY_PROP_ONLINE:
+		val->intval = chip->online;
+		break;
+	case POWER_SUPPLY_PROP_MODEL_NAME:
+		val->strval = MAX14656_NAME;
+		break;
+	case POWER_SUPPLY_PROP_MANUFACTURER:
+		val->strval = MAX14656_MANUFACTURER;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static enum power_supply_property max14656_battery_props[] = {
+	POWER_SUPPLY_PROP_ONLINE,
+	POWER_SUPPLY_PROP_MODEL_NAME,
+	POWER_SUPPLY_PROP_MANUFACTURER,
+};
+
+static int max14656_probe(struct i2c_client *client,
+			  const struct i2c_device_id *id)
+{
+	struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);
+	struct device *dev = &client->dev;
+	struct power_supply_config psy_cfg = {};
+	struct max14656_chip *chip;
+	int irq = client->irq;
+	int ret = 0;
+
+	if (irq <= 0) {
+		dev_err(dev, "invalid irq number: %d\n", irq);
+		return -ENODEV;
+	}
+
+	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA)) {
+		dev_err(dev, "No support for SMBUS_BYTE_DATA\n");
+		return -ENODEV;
+	}
+
+	chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
+	if (!chip)
+		return -ENOMEM;
+
+	psy_cfg.drv_data = chip;
+	chip->client = client;
+	chip->online = 0;
+	chip->psy_desc.name = MAX14656_NAME;
+	chip->psy_desc.type = POWER_SUPPLY_TYPE_UNKNOWN;
+	chip->psy_desc.properties = max14656_battery_props;
+	chip->psy_desc.num_properties = ARRAY_SIZE(max14656_battery_props);
+	chip->psy_desc.get_property = max14656_get_property;
+	chip->irq = irq;
+
+	ret = max14656_hw_init(chip);
+	if (ret)
+		return -ENODEV;
+
+	INIT_DELAYED_WORK(&chip->irq_work, max14656_irq_worker);
+
+	ret = devm_request_irq(dev, chip->irq, max14656_irq,
+			       IRQF_TRIGGER_FALLING,
+			       MAX14656_NAME, chip);
+	if (ret) {
+		dev_err(dev, "request_irq %d failed\n", chip->irq);
+		return -EINVAL;
+	}
+	enable_irq_wake(chip->irq);
+
+	chip->detect_psy = devm_power_supply_register(dev,
+		       &chip->psy_desc, &psy_cfg);
+	if (IS_ERR(chip->detect_psy)) {
+		dev_err(dev, "power_supply_register failed\n");
+		return -EINVAL;
+	}
+
+	schedule_delayed_work(&chip->irq_work, msecs_to_jiffies(2000));
+
+	return 0;
+}
+
+static const struct i2c_device_id max14656_id[] = {
+	{ "max14656", 0 },
+	{}
+};
+
+static const struct of_device_id max14656_match_table[] = {
+	{ .compatible = "maxim,max14656", },
+	{}
+};
+
+static struct i2c_driver max14656_i2c_driver = {
+	.driver = {
+		.name	= "max14656",
+		.owner	= THIS_MODULE,
+		.of_match_table = max14656_match_table,
+	},
+	.probe		= max14656_probe,
+	.id_table	= max14656_id,
+};
+module_i2c_driver(max14656_i2c_driver);
+
+MODULE_DESCRIPTION("MAX14656 USB charger detector");
+MODULE_LICENSE("GPL v2");