Date:	Fri, 27 Aug 2010 15:50:43 -0700
From:	rklein@...dia.com
To:	cbouatmailru@...il.com
Cc:	linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
	olof@...om.net, achew@...dia.com, Rhyland Klein <rklein@...dia.com>
Subject: [PATCH 1/1] power supply: add driver for TI BQ20Z75 gas gauge IC

From: Rhyland Klein <rklein@...dia.com>

this driver depends on I2C and uses SMBUS for communication with the host.

Signed-off-by: Rhyland Klein <rklein@...dia.com>
---
 drivers/power/Kconfig   |    7 +
 drivers/power/Makefile  |    1 +
 drivers/power/bq20z75.c |  403 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 411 insertions(+), 0 deletions(-)
 create mode 100644 drivers/power/bq20z75.c

diff --git a/drivers/power/Kconfig b/drivers/power/Kconfig
index 8e9ba17..c72e628 100644
--- a/drivers/power/Kconfig
+++ b/drivers/power/Kconfig
@@ -142,4 +142,11 @@ config CHARGER_PCF50633
 	help
 	 Say Y to include support for NXP PCF50633 Main Battery Charger.
 
+config BQ20Z75_GASGAUGE
+        tristate "TI BQ20Z75 GAS GAUGE"
+        depends on I2C
+        help
+         Say Y to include support for TI BQ20Z75 SBS-compliant
+         gas gauge and protection IC.
+
 endif # POWER_SUPPLY
diff --git a/drivers/power/Makefile b/drivers/power/Makefile
index 0005080..98abc31 100644
--- a/drivers/power/Makefile
+++ b/drivers/power/Makefile
@@ -34,3 +34,4 @@ obj-$(CONFIG_BATTERY_DA9030)	+= da9030_battery.o
 obj-$(CONFIG_BATTERY_MAX17040)	+= max17040_battery.o
 obj-$(CONFIG_BATTERY_Z2)	+= z2_battery.o
 obj-$(CONFIG_CHARGER_PCF50633)	+= pcf50633-charger.o
+obj-$(CONFIG_BQ20Z75_GASGAUGE)  += bq20z75.o
diff --git a/drivers/power/bq20z75.c b/drivers/power/bq20z75.c
new file mode 100644
index 0000000..4eb6638
--- /dev/null
+++ b/drivers/power/bq20z75.c
@@ -0,0 +1,403 @@
+/*
+ * drivers/power/bq20z75.c
+ *
+ * Gas Gauge driver for TI's BQ20Z75
+ *
+ * Copyright (c) 2010, NVIDIA Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/err.h>
+#include <linux/debugfs.h>
+#include <linux/power_supply.h>
+#include <linux/i2c.h>
+#include <linux/slab.h>
+
+enum {
+	REG_MANUFACTURER_DATA,
+	REG_TEMPERATURE,
+	REG_VOLTAGE,
+	REG_CURRENT,
+	REG_CAPACITY,
+	REG_TIME_TO_EMPTY,
+	REG_TIME_TO_FULL,
+	REG_STATUS,
+	REG_CYCLE_COUNT,
+	REG_SERIAL_NUMBER,
+	REG_MAX
+};
+
+#define BATTERY_MANUFACTURER_SIZE	12
+#define BATTERY_NAME_SIZE		8
+
+/* manufacturer access defines */
+#define MANUFACTURER_ACCESS_STATUS	0x0006
+#define MANUFACTURER_ACCESS_SLEEP	0x0011
+
+/* battery status value bits */
+#define BATTERY_CHARGING		0x40
+#define BATTERY_FULL_CHARGED		0x20
+#define BATTERY_FULL_DISCHARGED		0x10
+
+#define BQ20Z75_DATA(_psp, _addr, _min_value, _max_value) { \
+	.psp = _psp, \
+	.addr = _addr, \
+	.min_value = _min_value, \
+	.max_value = _max_value, \
+}
+
+static struct bq20z75_device_data {
+	enum power_supply_property psp;
+	u8 addr;
+	int min_value;
+	int max_value;
+} bq20z75_data[] = {
+	[REG_MANUFACTURER_DATA] =
+		BQ20Z75_DATA(POWER_SUPPLY_PROP_PRESENT, 0x00, 0, 65535),
+	[REG_TEMPERATURE] =
+		BQ20Z75_DATA(POWER_SUPPLY_PROP_TEMP, 0x08, 0, 65535),
+	[REG_VOLTAGE] =
+		BQ20Z75_DATA(POWER_SUPPLY_PROP_VOLTAGE_NOW, 0x09, 0, 20000),
+	[REG_CURRENT] =
+		BQ20Z75_DATA(POWER_SUPPLY_PROP_CURRENT_NOW, 0x0A, -32768, \
+			32767),
+	[REG_CAPACITY] =
+		BQ20Z75_DATA(POWER_SUPPLY_PROP_CAPACITY, 0x0e, 0, 100),
+	[REG_TIME_TO_EMPTY] =
+		BQ20Z75_DATA(POWER_SUPPLY_PROP_TIME_TO_EMPTY_AVG, 0x12, 0, \
+			65535),
+	[REG_TIME_TO_FULL] =
+		BQ20Z75_DATA(POWER_SUPPLY_PROP_TIME_TO_FULL_AVG, 0x13, 0, \
+			65535),
+	[REG_STATUS] =
+		BQ20Z75_DATA(POWER_SUPPLY_PROP_STATUS, 0x16, 0, 65535),
+	[REG_CYCLE_COUNT] =
+		BQ20Z75_DATA(POWER_SUPPLY_PROP_CYCLE_COUNT, 0x17, 0, 65535),
+	[REG_SERIAL_NUMBER] =
+		BQ20Z75_DATA(POWER_SUPPLY_PROP_SERIAL_NUMBER, 0x1C, 0, 65535),
+};
+
+static enum power_supply_property bq20z75_properties[] = {
+	POWER_SUPPLY_PROP_STATUS,
+	POWER_SUPPLY_PROP_HEALTH,
+	POWER_SUPPLY_PROP_PRESENT,
+	POWER_SUPPLY_PROP_TECHNOLOGY,
+	POWER_SUPPLY_PROP_CYCLE_COUNT,
+	POWER_SUPPLY_PROP_VOLTAGE_NOW,
+	POWER_SUPPLY_PROP_CURRENT_NOW,
+	POWER_SUPPLY_PROP_CAPACITY,
+	POWER_SUPPLY_PROP_TEMP,
+	POWER_SUPPLY_PROP_TIME_TO_EMPTY_AVG,
+	POWER_SUPPLY_PROP_TIME_TO_FULL_AVG,
+	POWER_SUPPLY_PROP_SERIAL_NUMBER,
+};
+
+static int bq20z75_get_property(struct power_supply *psy,
+	enum power_supply_property psp, union power_supply_propval *val);
+
+static struct power_supply bq20z75_supply = {
+	.name = "battery",
+	.type = POWER_SUPPLY_TYPE_BATTERY,
+	.properties = bq20z75_properties,
+	.num_properties = ARRAY_SIZE(bq20z75_properties),
+	.get_property = bq20z75_get_property,
+};
+
+struct bq20z75_device_info {
+	struct i2c_client	*client;
+} *bq20z75_device;
+
+static int bq20z75_get_battery_presence_and_health(
+	enum power_supply_property psp,	union power_supply_propval *val)
+{
+	s32 ret;
+
+	/* Write to ManufacturerAccess with
+	 * ManufacturerAccess command and then
+	 * read the status */
+	ret = i2c_smbus_write_word_data(bq20z75_device->client,
+		bq20z75_data[REG_MANUFACTURER_DATA].addr,
+		MANUFACTURER_ACCESS_STATUS);
+	if (ret < 0) {
+		dev_err(&bq20z75_device->client->dev,
+			"%s: i2c write for battery presence failed\n",
+			__func__);
+		return -EINVAL;
+	}
+
+	ret = i2c_smbus_read_word_data(bq20z75_device->client,
+		bq20z75_data[REG_MANUFACTURER_DATA].addr);
+	if (ret < 0) {
+		dev_err(&bq20z75_device->client->dev,
+			"%s: i2c read for battery presence failed\n",
+			__func__);
+		return -EINVAL;
+	}
+
+	if (ret < bq20z75_data[REG_MANUFACTURER_DATA].min_value ||
+	    ret > bq20z75_data[REG_MANUFACTURER_DATA].max_value) {
+		val->intval = 0;
+		return 0;
+	}
+
+	/* Mask the upper nibble of 2nd byte and
+	 * lower byte of response then
+	 * shift the result by 8 to get status*/
+	ret &= 0x0F00;
+	ret >>= 8;
+	if (psp == POWER_SUPPLY_PROP_PRESENT) {
+		if (ret == 0x0F)
+			/* battery removed */
+			val->intval = 0;
+		else
+			val->intval = 1;
+	} else if (psp == POWER_SUPPLY_PROP_HEALTH) {
+		if (ret == 0x09)
+			val->intval = POWER_SUPPLY_HEALTH_UNSPEC_FAILURE;
+		else if (ret == 0x0B)
+			val->intval = POWER_SUPPLY_HEALTH_OVERHEAT;
+		else if (ret == 0x0C)
+			val->intval = POWER_SUPPLY_HEALTH_DEAD;
+		else
+			val->intval = POWER_SUPPLY_HEALTH_GOOD;
+	}
+
+	return 0;
+}
+
+static int bq20z75_get_battery_property(int reg_offset,
+	enum power_supply_property psp,
+	union power_supply_propval *val)
+{
+	s32 ret;
+
+	ret = i2c_smbus_read_word_data(bq20z75_device->client,
+		bq20z75_data[reg_offset].addr);
+	if (ret < 0) {
+		dev_err(&bq20z75_device->client->dev,
+			"%s: i2c read for %d failed\n", __func__, reg_offset);
+		return -EINVAL;
+	}
+
+	if (ret >= bq20z75_data[reg_offset].min_value &&
+	    ret <= bq20z75_data[reg_offset].max_value) {
+		val->intval = ret;
+		if (psp == POWER_SUPPLY_PROP_STATUS) {
+			/* mask the upper byte and then find the
+			 * actual status */
+			ret &= 0x00FF;
+			if (ret & BATTERY_CHARGING)
+				val->intval = POWER_SUPPLY_STATUS_CHARGING;
+			else if (ret & BATTERY_FULL_CHARGED)
+				val->intval = POWER_SUPPLY_STATUS_FULL;
+			else if (ret & BATTERY_FULL_DISCHARGED)
+				val->intval = POWER_SUPPLY_STATUS_NOT_CHARGING;
+			else
+				val->intval = POWER_SUPPLY_STATUS_DISCHARGING;
+		}
+		/* bq20z75 provides battery tempreture in 0.1°K
+		 * so convert it to °C */
+		else if (psp == POWER_SUPPLY_PROP_TEMP)
+			val->intval = ret - 2731;
+	} else {
+		val->intval = 0;
+		if (psp == POWER_SUPPLY_PROP_STATUS)
+			val->intval = POWER_SUPPLY_STATUS_UNKNOWN;
+	}
+
+	return 0;
+}
+
+static int bq20z75_get_battery_capacity(union power_supply_propval *val)
+{
+	s32 ret;
+
+	ret = i2c_smbus_read_byte_data(bq20z75_device->client,
+		bq20z75_data[REG_CAPACITY].addr);
+	if (ret < 0) {
+		dev_err(&bq20z75_device->client->dev,
+			"%s: i2c read for %d failed\n", __func__, REG_CAPACITY);
+		return -EINVAL;
+	}
+
+	/* bq20z75 spec says that this can be >100 %
+	 * even if max value is 100 % */
+	val->intval = ((ret >= 100) ? 100 : ret);
+
+	return 0;
+}
+
+static int bq20z75_get_property(struct power_supply *psy,
+	enum power_supply_property psp,
+	union power_supply_propval *val)
+{
+	u8 count;
+
+	switch (psp) {
+	case POWER_SUPPLY_PROP_PRESENT:
+	case POWER_SUPPLY_PROP_HEALTH:
+		if (bq20z75_get_battery_presence_and_health(psp, val))
+			return -EINVAL;
+		break;
+
+	case POWER_SUPPLY_PROP_TECHNOLOGY:
+		val->intval = POWER_SUPPLY_TECHNOLOGY_LION;
+		break;
+
+	case POWER_SUPPLY_PROP_CAPACITY:
+		if (bq20z75_get_battery_capacity(val))
+			return -EINVAL;
+		break;
+
+	case POWER_SUPPLY_PROP_STATUS:
+	case POWER_SUPPLY_PROP_CYCLE_COUNT:
+	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
+	case POWER_SUPPLY_PROP_CURRENT_NOW:
+	case POWER_SUPPLY_PROP_TEMP:
+	case POWER_SUPPLY_PROP_TIME_TO_EMPTY_AVG:
+	case POWER_SUPPLY_PROP_TIME_TO_FULL_AVG:
+	case POWER_SUPPLY_PROP_SERIAL_NUMBER:
+		for (count = 0; count < REG_MAX; count++) {
+			if (psp == bq20z75_data[count].psp)
+				break;
+		}
+
+		if (bq20z75_get_battery_property(count, psp, val))
+			return -EINVAL;
+			break;
+
+	default:
+		dev_err(&bq20z75_device->client->dev,
+			"%s: INVALID property\n", __func__);
+		return -EINVAL;
+	}
+
+	printk(KERN_INFO "%s: property = %d, value = %d\n", __func__,
+		psp, val->intval);
+
+	return 0;
+}
+
+static int bq20z75_probe(struct i2c_client *client,
+	const struct i2c_device_id *id)
+{
+	int rc;
+
+	bq20z75_device = kzalloc(sizeof(*bq20z75_device), GFP_KERNEL);
+	if (!bq20z75_device)
+		return -ENOMEM;
+
+memset(bq20z75_device, 0, sizeof(*bq20z75_device));
+
+	bq20z75_device->client = client;
+	i2c_set_clientdata(client, bq20z75_device);
+
+	rc = power_supply_register(&client->dev, &bq20z75_supply);
+	if (rc) {
+		dev_err(&bq20z75_device->client->dev,
+			"%s: Failed to register power supply\n", __func__);
+		kfree(bq20z75_device);
+		return rc;
+	}
+
+	dev_info(&bq20z75_device->client->dev,
+		"%s: battery driver registered\n", client->name);
+
+	return 0;
+}
+
+static int bq20z75_remove(struct i2c_client *client)
+{
+	struct bq20z75_device_info *bq20z75_device = i2c_get_clientdata(client);
+
+	power_supply_unregister(&bq20z75_supply);
+	kfree(bq20z75_device);
+	bq20z75_device = NULL;
+
+	return 0;
+}
+
+#if defined CONFIG_PM
+static int bq20z75_suspend(struct i2c_client *client,
+	pm_message_t state)
+{
+	s32 ret;
+	struct bq20z75_device_info *bq20z75_device = i2c_get_clientdata(client);
+
+	/* write to manufacture access with sleep command */
+	ret = i2c_smbus_write_word_data(bq20z75_device->client,
+		bq20z75_data[REG_MANUFACTURER_DATA].addr,
+		MANUFACTURER_ACCESS_SLEEP);
+	if (ret < 0) {
+		dev_err(&bq20z75_device->client->dev,
+			"%s: i2c write for %d failed\n",
+			__func__, MANUFACTURER_ACCESS_SLEEP);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/* any smbus transaction will wake up bq20z75 */
+static int bq20z75_resume(struct i2c_client *client)
+{
+	return 0;
+}
+#endif
+
+static const struct i2c_device_id bq20z75_id[] = {
+	{ "bq20z75-battery", 0 },
+	{},
+};
+
+static struct i2c_driver bq20z75_battery_driver = {
+	.probe		= bq20z75_probe,
+	.remove		= bq20z75_remove,
+#if defined CONFIG_PM
+	.suspend	= bq20z75_suspend,
+	.resume		= bq20z75_resume,
+#endif
+	.id_table	= bq20z75_id,
+	.driver = {
+		.name	= "bq20z75-battery",
+	},
+};
+
+static int __init bq20z75_battery_init(void)
+{
+	int ret;
+
+	ret = i2c_add_driver(&bq20z75_battery_driver);
+	if (ret)
+		dev_err(&bq20z75_device->client->dev,
+			"%s: i2c_add_driver failed\n", __func__);
+
+	return ret;
+}
+module_init(bq20z75_battery_init);
+
+static void __exit bq20z75_battery_exit(void)
+{
+	i2c_del_driver(&bq20z75_battery_driver);
+}
+module_exit(bq20z75_battery_exit);
+
+MODULE_AUTHOR("NVIDIA Graphics Pvt Ltd");
+MODULE_DESCRIPTION("BQ20z75 battery monitor driver");
+MODULE_LICENSE("GPL");
-- 
1.7.0.4

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