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Subject[PATCH] ds2782 battery gas gauge driver
Add support for the the ds2782 standalone I2C gas-gauge.

Signed-off-by: Ryan Mallon <ryan@bluewatersys.com>

---

diff --git a/drivers/power/Kconfig b/drivers/power/Kconfig
index 33da112..b9c818f 100644
--- a/drivers/power/Kconfig
+++ b/drivers/power/Kconfig
@@ -43,6 +43,13 @@ config BATTERY_DS2760
help
Say Y here to enable support for batteries with ds2760 chip.

+config BATTERY_DS2782
+ tristate "DS2782 standalone gas-gauge"
+ depends on I2C
+ help
+ Say Y here to enable support for the DS2782 standalone battery
+ gas-gauge.
+
config BATTERY_PMU
tristate "Apple PMU battery"
depends on PPC32 && ADB_PMU
diff --git a/drivers/power/Makefile b/drivers/power/Makefile
index 2fcf41d..ad1ac61 100644
--- a/drivers/power/Makefile
+++ b/drivers/power/Makefile
@@ -19,6 +19,7 @@ obj-$(CONFIG_APM_POWER) += apm_power.o
obj-$(CONFIG_WM8350_POWER) += wm8350_power.o

obj-$(CONFIG_BATTERY_DS2760) += ds2760_battery.o
+obj-$(CONFIG_BATTERY_DS2782) += ds2782_battery.o
obj-$(CONFIG_BATTERY_PMU) += pmu_battery.o
obj-$(CONFIG_BATTERY_OLPC) += olpc_battery.o
obj-$(CONFIG_BATTERY_TOSA) += tosa_battery.o
diff --git a/drivers/power/ds2782_battery.c b/drivers/power/ds2782_battery.c
new file mode 100644
index 0000000..8697891
--- /dev/null
+++ b/drivers/power/ds2782_battery.c
@@ -0,0 +1,269 @@
+/*
+ * drivers/power/ds2782_battery.c
+ *
+ * I2C client/driver for the Maxim/Dallas DS2782 Stand-Alone Fuel Gauge IC
+ *
+ * Copyright (C) 2009 Bluewater Systems Ltd
+ * Author: Ryan Mallon <ryan@bluewatersys.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.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/idr.h>
+#include <linux/power_supply.h>
+
+#define DS2782_REG_RARC 0x06 /* Remaining active relative capacity */
+
+#define DS2782_REG_VOLT_MSB 0x0c
+#define DS2782_REG_TEMP_MSB 0x0a
+#define DS2782_REG_CURRENT_MSB 0x0e
+
+/* EEPROM Block */
+#define DS2782_REG_RSNSP 0x69 /* Sense resistor value */
+
+/* Current unit measurement in uA for a 1 milli-ohm sense resistor */
+#define DS2782_CURRENT_UNITS 1563
+
+#define to_ds2782_info(x) container_of(x, struct ds2782_info, battery)
+
+struct ds2782_info {
+ struct i2c_client *client;
+ struct power_supply battery;
+ int id;
+};
+
+static DEFINE_IDR(battery_id);
+static DEFINE_MUTEX(battery_lock);
+
+static inline u8 ds2782_read_reg(struct ds2782_info *info, int reg)
+{
+ return i2c_smbus_read_byte_data(info->client, reg);
+}
+
+static inline u16 ds2782_read_reg16(struct ds2782_info *info, int reg_msb)
+{
+ u8 msb, lsb;
+
+ msb = ds2782_read_reg(info, reg_msb);
+ lsb = ds2782_read_reg(info, reg_msb + 1);
+
+ return (msb << 8) | lsb;
+}
+
+static int ds2782_get_temp(struct ds2782_info *info)
+{
+ u16 raw;
+ s16 temp;
+
+ /* Temperature is measured in units of 0.125 degrees celcius */
+ raw = ds2782_read_reg16(info, DS2782_REG_TEMP_MSB);
+ temp = (raw >> 5) & 0x7ff;
+ if (raw & (1 << 15))
+ temp |= 0xf800;
+ return (temp * 125) / 100;
+}
+
+static int ds2782_get_current(struct ds2782_info *info)
+{
+ s16 current_uA;
+ int sense_res;
+
+ /*
+ * The units of measurement for current are dependent on the value of
+ * the sense resistor.
+ */
+ sense_res = 1000 / ds2782_read_reg(info, DS2782_REG_RSNSP);
+ dev_dbg(&info->client->dev, "sense resistor = %d milli-ohms\n",
+ sense_res);
+ current_uA = ds2782_read_reg16(info, DS2782_REG_CURRENT_MSB);
+ return current_uA * (DS2782_CURRENT_UNITS / sense_res);
+}
+
+static int ds2782_get_voltage(struct ds2782_info *info)
+{
+ u16 raw;
+ s16 voltage_uA;
+
+ /* Voltage is measured in units of 4.88mV */
+ raw = ds2782_read_reg16(info, DS2782_REG_VOLT_MSB);
+ voltage_uA = (raw >> 5) & 0x7ff;
+ if (raw & (1 << 15))
+ voltage_uA |= 0xf800;
+ return voltage_uA * 4880;
+}
+
+static int ds2782_get_status(struct ds2782_info *info)
+{
+ int current_uA, capacity;
+
+ current_uA = ds2782_get_current(info);
+ capacity = ds2782_read_reg(info, DS2782_REG_RARC);
+
+ if (capacity == 100)
+ return POWER_SUPPLY_STATUS_FULL;
+ else if (current_uA == 0)
+ return POWER_SUPPLY_STATUS_NOT_CHARGING;
+ else if (current_uA < 0)
+ return POWER_SUPPLY_STATUS_DISCHARGING;
+ else
+ return POWER_SUPPLY_STATUS_CHARGING;
+}
+
+static int ds2782_battery_get_property(struct power_supply *psy,
+ enum power_supply_property prop,
+ union power_supply_propval *val)
+{
+ struct ds2782_info *info = to_ds2782_info(psy);
+
+ switch (prop) {
+ case POWER_SUPPLY_PROP_STATUS:
+ val->intval = ds2782_get_status(info);
+ break;
+
+ case POWER_SUPPLY_PROP_CAPACITY:
+ val->intval = ds2782_read_reg(info, DS2782_REG_RARC);
+ break;
+
+ case POWER_SUPPLY_PROP_VOLTAGE_NOW:
+ val->intval = ds2782_get_voltage(info);
+ break;
+
+ case POWER_SUPPLY_PROP_CURRENT_NOW:
+ val->intval = ds2782_get_current(info);
+ break;
+
+ case POWER_SUPPLY_PROP_TEMP:
+ val->intval = ds2782_get_temp(info);
+ break;
+
+ default:
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static enum power_supply_property ds2782_battery_props[] = {
+ POWER_SUPPLY_PROP_STATUS,
+ POWER_SUPPLY_PROP_CAPACITY,
+ POWER_SUPPLY_PROP_VOLTAGE_NOW,
+ POWER_SUPPLY_PROP_CURRENT_NOW,
+ POWER_SUPPLY_PROP_TEMP,
+};
+
+static void ds2782_power_supply_init(struct power_supply *battery)
+{
+ battery->type = POWER_SUPPLY_TYPE_BATTERY;
+ battery->properties = ds2782_battery_props;
+ battery->num_properties = ARRAY_SIZE(ds2782_battery_props);
+ battery->get_property = ds2782_battery_get_property;
+ battery->external_power_changed = NULL;
+}
+
+static int ds2782_battery_remove(struct i2c_client *client)
+{
+ struct ds2782_info *info = i2c_get_clientdata(client);
+
+ power_supply_unregister(&info->battery);
+ kfree(info->battery.name);
+
+ mutex_lock(&battery_lock);
+ idr_remove(&battery_id, info->id);
+ mutex_unlock(&battery_lock);
+
+ kfree(info);
+ return 0;
+}
+
+static int ds2782_battery_probe(struct i2c_client *client,
+ const struct i2c_device_id *id)
+{
+ struct ds2782_info *info;
+ int ret, num;
+
+ /* Get an ID for this battery */
+ ret = idr_pre_get(&battery_id, GFP_KERNEL);
+ if (ret == 0) {
+ ret = -ENOMEM;
+ goto fail_id;
+ }
+
+ mutex_lock(&battery_lock);
+ ret = idr_get_new(&battery_id, client, &num);
+ mutex_unlock(&battery_lock);
+ if (ret < 0)
+ return ret;
+
+ info = kzalloc(sizeof(struct ds2782_info), GFP_KERNEL);
+ if (!info) {
+ ret = -ENOMEM;
+ goto fail_info;
+ }
+
+ info->battery.name = kasprintf(GFP_KERNEL, "ds2782-%d", num);
+ if (!info->battery.name) {
+ ret = -ENOMEM;
+ goto fail_name;
+ }
+
+ i2c_set_clientdata(client, info);
+ info->client = client;
+ ds2782_power_supply_init(&info->battery);
+
+ ret = power_supply_register(&client->dev, &info->battery);
+ if (ret) {
+ dev_err(&client->dev, "failed to register battery\n");
+ goto fail_register;
+ }
+
+ return 0;
+
+fail_register:
+ kfree(info->battery.name);
+fail_name:
+ kfree(info);
+fail_info:
+ mutex_lock(&battery_lock);
+ idr_remove(&battery_id, num);
+ mutex_unlock(&battery_lock);
+fail_id:
+ return ret;
+}
+
+static const struct i2c_device_id ds2782_id[] = {
+ {"ds2782", 0},
+ {},
+};
+
+static struct i2c_driver ds2782_battery_driver = {
+ .driver = {
+ .name = "ds2782-battery",
+ },
+ .probe = ds2782_battery_probe,
+ .remove = ds2782_battery_remove,
+ .id_table = ds2782_id,
+};
+
+static int __init ds2782_init(void)
+{
+ return i2c_add_driver(&ds2782_battery_driver);
+}
+
+static void __exit ds2782_exit(void)
+{
+ i2c_del_driver(&ds2782_battery_driver);
+}
+
+module_init(ds2782_init);
+module_exit(ds2782_exit);
+
+MODULE_AUTHOR("Ryan Mallon <ryan@bluewatersys.com>");
+MODULE_DESCRIPTION("Maxim/Dallas DS2782 Stand-Alone Fuel Gauage IC driver");
+MODULE_LICENSE("GPL");
+


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