Add ds2782 battery gas gauge driver

This patch adds a driver for ds2782 battery devices.

Signed-off-by: Ryan Mallon <ryan@bluewatersys.com>
Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>

3 files changed, 338 insertions, 0 deletions

diff --git a/drivers/power/Kconfig b/drivers/power/Kconfig
index 7eda34838bfe..bdbc4f73fcdc 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 daf3179689aa..380d17c9ae29 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 000000000000..da14f374cb60
--- /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");