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-rw-r--r--drivers/power/ds2782_battery.c330
1 files changed, 330 insertions, 0 deletions
diff --git a/drivers/power/ds2782_battery.c b/drivers/power/ds2782_battery.c
new file mode 100644
index 0000000..da14f37
--- /dev/null
+++ b/drivers/power/ds2782_battery.c
@@ -0,0 +1,330 @@
+/*
+ * 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/types.h>
+#include <linux/errno.h>
+#include <linux/swab.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 int ds2782_read_reg(struct ds2782_info *info, int reg, u8 *val)
+{
+ int ret;
+
+ ret = i2c_smbus_read_byte_data(info->client, reg);
+ if (ret < 0) {
+ dev_err(&info->client->dev, "register read failed\n");
+ return ret;
+ }
+
+ *val = ret;
+ return 0;
+}
+
+static inline int ds2782_read_reg16(struct ds2782_info *info, int reg_msb,
+ s16 *val)
+{
+ int ret;
+
+ ret = swab16(i2c_smbus_read_word_data(info->client, reg_msb));
+ if (ret < 0) {
+ dev_err(&info->client->dev, "register read failed\n");
+ return ret;
+ }
+
+ *val = ret;
+ return 0;
+}
+
+static int ds2782_get_temp(struct ds2782_info *info, int *temp)
+{
+ s16 raw;
+ int err;
+
+ /*
+ * Temperature is measured in units of 0.125 degrees celcius, the
+ * power_supply class measures temperature in tenths of degrees
+ * celsius. The temperature value is stored as a 10 bit number, plus
+ * sign in the upper bits of a 16 bit register.
+ */
+ err = ds2782_read_reg16(info, DS2782_REG_TEMP_MSB, &raw);
+ if (err)
+ return err;
+ *temp = ((raw / 32) * 125) / 100;
+ return 0;
+}
+
+static int ds2782_get_current(struct ds2782_info *info, int *current_uA)
+{
+ int sense_res;
+ int err;
+ u8 sense_res_raw;
+ s16 raw;
+
+ /*
+ * The units of measurement for current are dependent on the value of
+ * the sense resistor.
+ */
+ err = ds2782_read_reg(info, DS2782_REG_RSNSP, &sense_res_raw);
+ if (err)
+ return err;
+ if (sense_res_raw == 0) {
+ dev_err(&info->client->dev, "sense resistor value is 0\n");
+ return -ENXIO;
+ }
+ sense_res = 1000 / sense_res_raw;
+
+ dev_dbg(&info->client->dev, "sense resistor = %d milli-ohms\n",
+ sense_res);
+ err = ds2782_read_reg16(info, DS2782_REG_CURRENT_MSB, &raw);
+ if (err)
+ return err;
+ *current_uA = raw * (DS2782_CURRENT_UNITS / sense_res);
+ return 0;
+}
+
+static int ds2782_get_voltage(struct ds2782_info *info, int *voltage_uA)
+{
+ s16 raw;
+ int err;
+
+ /*
+ * Voltage is measured in units of 4.88mV. The voltage is stored as
+ * a 10-bit number plus sign, in the upper bits of a 16-bit register
+ */
+ err = ds2782_read_reg16(info, DS2782_REG_VOLT_MSB, &raw);
+ if (err)
+ return err;
+ *voltage_uA = (raw / 32) * 4800;
+ return 0;
+}
+
+static int ds2782_get_capacity(struct ds2782_info *info, int *capacity)
+{
+ int err;
+ u8 raw;
+
+ err = ds2782_read_reg(info, DS2782_REG_RARC, &raw);
+ if (err)
+ return err;
+ *capacity = raw;
+ return raw;
+}
+
+static int ds2782_get_status(struct ds2782_info *info, int *status)
+{
+ int err;
+ int current_uA;
+ int capacity;
+
+ err = ds2782_get_current(info, &current_uA);
+ if (err)
+ return err;
+
+ err = ds2782_get_capacity(info, &capacity);
+ if (err)
+ return err;
+
+ if (capacity == 100)
+ *status = POWER_SUPPLY_STATUS_FULL;
+ else if (current_uA == 0)
+ *status = POWER_SUPPLY_STATUS_NOT_CHARGING;
+ else if (current_uA < 0)
+ *status = POWER_SUPPLY_STATUS_DISCHARGING;
+ else
+ *status = POWER_SUPPLY_STATUS_CHARGING;
+
+ return 0;
+}
+
+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);
+ int ret;
+
+ switch (prop) {
+ case POWER_SUPPLY_PROP_STATUS:
+ ret = ds2782_get_status(info, &val->intval);
+ break;
+
+ case POWER_SUPPLY_PROP_CAPACITY:
+ ret = ds2782_get_capacity(info, &val->intval);
+ break;
+
+ case POWER_SUPPLY_PROP_VOLTAGE_NOW:
+ ret = ds2782_get_voltage(info, &val->intval);
+ break;
+
+ case POWER_SUPPLY_PROP_CURRENT_NOW:
+ ret = ds2782_get_current(info, &val->intval);
+ break;
+
+ case POWER_SUPPLY_PROP_TEMP:
+ ret = ds2782_get_temp(info, &val->intval);
+ break;
+
+ default:
+ ret = -EINVAL;
+ }
+
+ return ret;
+}
+
+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);
+
+ i2c_set_clientdata(client, info);
+
+ 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;
+ int 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)
+ goto fail_id;
+
+ info = kzalloc(sizeof(*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:
+ i2c_set_clientdata(client, info);
+ 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);
+}
+module_init(ds2782_init);
+
+static void __exit ds2782_exit(void)
+{
+ i2c_del_driver(&ds2782_battery_driver);
+}
+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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