add the new bq27441 driver from lars straight into the kernel tree, to avoid having to build a module every time

arch/arm/configs/zero-gravitas_defconfig

@@ -140,7 +140,7 @@ CONFIG_I2C_IMX=y
 CONFIG_SPI=y
 CONFIG_GPIO_SYSFS=y
 CONFIG_POWER_SUPPLY=y
-CONFIG_BATTERY_BQ27XXX=y
+CONFIG_BATTERY_BQ27441=y
 CONFIG_CHARGER_GPIO=y
 CONFIG_POWER_RESET=y
 CONFIG_POWER_RESET_SYSCON=y

drivers/power/Kconfig

@@ -157,6 +157,12 @@ config BATTERY_SBS
 	  Say Y to include support for SBS battery driver for SBS-compliant
 	  gas gauges.
 
+config BATTERY_BQ27441
+	tristate "BQ27441 quote unqote advanced battery driver"
+	depends on I2C || I2C=n
+	help
+	  Say Y here to use a special driver for the BQ27441.
+
 config BATTERY_BQ27XXX
 	tristate "BQ27xxx battery driver"
 	depends on I2C || I2C=n

drivers/power/Makefile

@@ -29,6 +29,7 @@ obj-$(CONFIG_BATTERY_COLLIE)	+= collie_battery.o
 obj-$(CONFIG_BATTERY_IPAQ_MICRO) += ipaq_micro_battery.o
 obj-$(CONFIG_BATTERY_WM97XX)	+= wm97xx_battery.o
 obj-$(CONFIG_BATTERY_SBS)	+= sbs-battery.o
+obj-$(CONFIG_BATTERY_BQ27441)	+= bq27441/bq27441_battery.o bq27441/bq27xxx_battery.o bq27441/bq27xxx_battery_i2c.o
 obj-$(CONFIG_BATTERY_BQ27XXX)	+= bq27xxx_battery.o
 obj-$(CONFIG_BATTERY_BQ27XXX_I2C) += bq27xxx_battery_i2c.o
 obj-$(CONFIG_BATTERY_DA9030)	+= da9030_battery.o

drivers/power/bq27441/bq27441_battery.h

@@ -0,0 +1,7 @@
+#ifndef _BQ27441_BATTERY_H
+#define _BQ27441_BATTERY_H
+
+int bq27441_init(struct bq27xxx_device_info *di);
+int bq27441_exit(struct bq27xxx_device_info *di);
+
+#endif /* _BQ27441_BATTERY_H */

drivers/power/bq27441/bq27xxx_battery.h

@@ -0,0 +1,73 @@
+#ifndef __LINUX_BQ27X00_BATTERY_H__
+#define __LINUX_BQ27X00_BATTERY_H__
+
+enum bq27xxx_chip {
+	BQ27000 = 1, /* bq27000, bq27200 */
+	BQ27010, /* bq27010, bq27210 */
+	BQ27500, /* bq27500, bq27510, bq27520 */
+	BQ27530, /* bq27530, bq27531 */
+	BQ27541, /* bq27541, bq27542, bq27546, bq27742 */
+	BQ27545, /* bq27545 */
+	BQ27421, /* bq27421, bq27425, bq27441, bq27621 */
+};
+
+/**
+ * struct bq27xxx_plaform_data - Platform data for bq27xxx devices
+ * @name: Name of the battery.
+ * @chip: Chip class number of this device.
+ * @read: HDQ read callback.
+ *	This function should provide access to the HDQ bus the battery is
+ *	connected to.
+ *	The first parameter is a pointer to the battery device, the second the
+ *	register to be read. The return value should either be the content of
+ *	the passed register or an error value.
+ */
+struct bq27xxx_platform_data {
+	const char *name;
+	enum bq27xxx_chip chip;
+	int (*read)(struct device *dev, unsigned int);
+};
+
+struct bq27xxx_device_info;
+struct bq27xxx_access_methods {
+	int (*read)(struct bq27xxx_device_info *di, u8 reg, bool single);
+	int (*write)(struct bq27xxx_device_info *di, u8 reg, const u8 *data, size_t len);
+};
+
+struct bq27xxx_reg_cache {
+	int temperature;
+	int time_to_empty;
+	int time_to_empty_avg;
+	int time_to_full;
+	int charge_full;
+	int cycle_count;
+	int capacity;
+	int energy;
+	int flags;
+	int power_avg;
+	int health;
+};
+
+struct dentry;
+
+struct bq27xxx_device_info {
+	struct device *dev;
+	enum bq27xxx_chip chip;
+	const char *name;
+	struct bq27xxx_access_methods bus;
+	struct bq27xxx_reg_cache cache;
+	int charge_design_full;
+	unsigned long last_update;
+	struct delayed_work work;
+	struct power_supply *bat;
+	struct mutex lock;
+	u8 *regs;
+	struct dentry *dfs_dir;
+	struct dentry *dfs_polarity_file;
+};
+
+void bq27xxx_battery_update(struct bq27xxx_device_info *di);
+int bq27xxx_battery_setup(struct bq27xxx_device_info *di);
+void bq27xxx_battery_teardown(struct bq27xxx_device_info *di);
+
+#endif

drivers/power/bq27441/bq27xxx_battery_i2c.c

@@ -0,0 +1,202 @@
+/*
+ * SCI Reset driver for Keystone based devices
+ *
+ * Copyright (C) 2015 Texas Instruments Incorporated - http://www.ti.com/
+ *	Andrew F. Davis <afd@ti.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 "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <asm/unaligned.h>
+#include <linux/slab.h>
+
+#include <linux/string.h>
+
+#include "bq27xxx_battery.h"
+
+static irqreturn_t bq27xxx_battery_irq_handler_thread(int irq, void *data)
+{
+	struct bq27xxx_device_info *di = data;
+
+	bq27xxx_battery_update(di);
+
+	return IRQ_HANDLED;
+}
+
+static int bq27xxx_battery_i2c_read(struct bq27xxx_device_info *di, u8 reg,
+				    bool single)
+{
+	struct i2c_client *client = to_i2c_client(di->dev);
+	struct i2c_msg msg[2];
+	unsigned char data[2];
+	int ret;
+
+	if (!client->adapter)
+		return -ENODEV;
+
+	msg[0].addr = client->addr;
+	msg[0].flags = 0;
+	msg[0].buf = &reg;
+	msg[0].len = sizeof(reg);
+	msg[1].addr = client->addr;
+	msg[1].flags = I2C_M_RD;
+	msg[1].buf = data;
+	if (single)
+		msg[1].len = 1;
+	else
+		msg[1].len = 2;
+
+	ret = i2c_transfer(client->adapter, msg, ARRAY_SIZE(msg));
+	if (ret < 0)
+		return ret;
+
+	if (!single)
+		ret = get_unaligned_le16(data);
+	else
+		ret = data[0];
+
+	return ret;
+}
+
+static int bq27xxx_battery_i2c_write(struct bq27xxx_device_info *di, u8 reg,
+				    const u8 *data, size_t len)
+{
+	struct i2c_client *client = to_i2c_client(di->dev);
+	int ret;
+	unsigned char *buf;
+
+	if (!client->adapter)
+		return -ENODEV;
+
+	buf = kzalloc(len + sizeof(reg), GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	buf[0] = reg;
+	memcpy (&buf[1], data, len);
+
+	ret = i2c_master_send(client, buf, len + sizeof(reg));
+
+	kfree(buf);
+
+	return ret;
+}
+
+static int bq27xxx_battery_i2c_probe(struct i2c_client *client,
+				     const struct i2c_device_id *id)
+{
+	struct bq27xxx_device_info *di;
+	int ret;
+
+	di = devm_kzalloc(&client->dev, sizeof(*di), GFP_KERNEL);
+	if (!di)
+		return -ENOMEM;
+
+	di->dev = &client->dev;
+	di->chip = id->driver_data;
+	di->name = id->name;
+	di->bus.read = bq27xxx_battery_i2c_read;
+	di->bus.write = bq27xxx_battery_i2c_write;
+
+	ret = bq27xxx_battery_setup(di);
+	if (ret)
+		return ret;
+
+	/* Schedule a polling after about 1 min */
+	schedule_delayed_work(&di->work, 60 * HZ);
+
+	i2c_set_clientdata(client, di);
+
+	if (client->irq) {
+		ret = devm_request_threaded_irq(&client->dev, client->irq,
+				NULL, bq27xxx_battery_irq_handler_thread,
+				IRQF_ONESHOT,
+				di->name, di);
+		if (ret) {
+			dev_err(&client->dev,
+				"Unable to register IRQ %d error %d\n",
+				client->irq, ret);
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
+static int bq27xxx_battery_i2c_remove(struct i2c_client *client)
+{
+	struct bq27xxx_device_info *di = i2c_get_clientdata(client);
+
+	bq27xxx_battery_teardown(di);
+
+	return 0;
+}
+
+static const struct i2c_device_id bq27xxx_i2c_id_table[] = {
+	{ "bq27200", BQ27000 },
+	{ "bq27210", BQ27010 },
+	{ "bq27500", BQ27500 },
+	{ "bq27510", BQ27500 },
+	{ "bq27520", BQ27500 },
+	{ "bq27530", BQ27530 },
+	{ "bq27531", BQ27530 },
+	{ "bq27541", BQ27541 },
+	{ "bq27542", BQ27541 },
+	{ "bq27546", BQ27541 },
+	{ "bq27742", BQ27541 },
+	{ "bq27545", BQ27545 },
+	{ "bq27421", BQ27421 },
+	{ "bq27425", BQ27421 },
+	{ "bq27441", BQ27421 },
+	{ "bq27621", BQ27421 },
+	{},
+};
+MODULE_DEVICE_TABLE(i2c, bq27xxx_i2c_id_table);
+
+#ifdef CONFIG_OF
+static const struct of_device_id bq27xxx_battery_i2c_of_match_table[] = {
+	{ .compatible = "ti,bq27200" },
+	{ .compatible = "ti,bq27210" },
+	{ .compatible = "ti,bq27500" },
+	{ .compatible = "ti,bq27510" },
+	{ .compatible = "ti,bq27520" },
+	{ .compatible = "ti,bq27530" },
+	{ .compatible = "ti,bq27531" },
+	{ .compatible = "ti,bq27541" },
+	{ .compatible = "ti,bq27542" },
+	{ .compatible = "ti,bq27546" },
+	{ .compatible = "ti,bq27742" },
+	{ .compatible = "ti,bq27545" },
+	{ .compatible = "ti,bq27421" },
+	{ .compatible = "ti,bq27425" },
+	{ .compatible = "ti,bq27441" },
+	{ .compatible = "ti,bq27621" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, bq27xxx_battery_i2c_of_match_table);
+#endif
+
+static struct i2c_driver bq27xxx_battery_i2c_driver = {
+	.driver = {
+		.name = "bq27xxx-battery",
+		.of_match_table = of_match_ptr(bq27xxx_battery_i2c_of_match_table),
+	},
+	.probe = bq27xxx_battery_i2c_probe,
+	.remove = bq27xxx_battery_i2c_remove,
+	.id_table = bq27xxx_i2c_id_table,
+};
+module_i2c_driver(bq27xxx_battery_i2c_driver);
+
+MODULE_AUTHOR("Andrew F. Davis <afd@ti.com>");
+MODULE_DESCRIPTION("BQ27xxx battery monitor i2c driver");
+MODULE_LICENSE("GPL");