3 files changed, 556 insertions, 0 deletions

diff --git a/drivers/power/Kconfig b/drivers/power/Kconfig
index a79f16afb588..27b751b995fb 100644
--- a/drivers/power/Kconfig
+++ b/drivers/power/Kconfig
@@ -388,6 +388,14 @@ config CHARGER_TPS65090
          Say Y here to enable support for battery charging with TPS65090
          PMIC chips.
 
+config BATTERY_GAUGE_LTC2941
+        tristate "LTC2941/LTC2943 Battery Gauge Driver"
+        depends on I2C
+        help
+          Say Y here to include support for LTC2941 and LTC2943 Battery
+          Gauge IC. The driver reports the charge count continuously, and
+          measures the voltage and temperature every 10 seconds.
+
 config AB8500_BM
         bool "AB8500 Battery Management Driver"
         depends on AB8500_CORE && AB8500_GPADC
diff --git a/drivers/power/Makefile b/drivers/power/Makefile
index 31216cb7e8a1..36f9e0d10111 100644
--- a/drivers/power/Makefile
+++ b/drivers/power/Makefile
@@ -20,6 +20,7 @@ obj-$(CONFIG_BATTERY_DS2760)	+= ds2760_battery.o
 obj-$(CONFIG_BATTERY_DS2780)    += ds2780_battery.o
 obj-$(CONFIG_BATTERY_DS2781)    += ds2781_battery.o
 obj-$(CONFIG_BATTERY_DS2782)    += ds2782_battery.o
+obj-$(CONFIG_BATTERY_GAUGE_LTC2941)     += ltc2941-battery-gauge.o
 obj-$(CONFIG_BATTERY_GOLDFISH)  += goldfish_battery.o
 obj-$(CONFIG_BATTERY_PMU)       += pmu_battery.o
 obj-$(CONFIG_BATTERY_OLPC)      += olpc_battery.o
diff --git a/drivers/power/ltc2941-battery-gauge.c b/drivers/power/ltc2941-battery-gauge.c
new file mode 100644
index 000000000000..e31c927a6d16
--- /dev/null
+++ b/drivers/power/ltc2941-battery-gauge.c
@@ -0,0 +1,547 @@
+/*
+ * I2C client/driver for the Linear Technology LTC2941 and LTC2943
+ * Battery Gas Gauge IC
+ *
+ * Copyright (C) 2014 Topic Embedded Systems
+ *
+ * Author: Auryn Verwegen
+ * Author: Mike Looijmans
+ */
+#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/delay.h>
+#include <linux/idr.h>
+#include <linux/power_supply.h>
+#include <linux/slab.h>
+
+#define I16_MSB(x)                      ((x >> 8) & 0xFF)
+#define I16_LSB(x)                      (x & 0xFF)
+
+#define LTC294X_WORK_DELAY              10      /* Update delay in seconds */
+
+#define LTC294X_MAX_VALUE               0xFFFF
+#define LTC294X_MID_SUPPLY              0x7FFF
+
+#define LTC2941_MAX_PRESCALER_EXP       7
+#define LTC2943_MAX_PRESCALER_EXP       6
+
+enum ltc294x_reg {
+        LTC294X_REG_STATUS              = 0x00,
+        LTC294X_REG_CONTROL             = 0x01,
+        LTC294X_REG_ACC_CHARGE_MSB      = 0x02,
+        LTC294X_REG_ACC_CHARGE_LSB      = 0x03,
+        LTC294X_REG_THRESH_HIGH_MSB     = 0x04,
+        LTC294X_REG_THRESH_HIGH_LSB     = 0x05,
+        LTC294X_REG_THRESH_LOW_MSB      = 0x06,
+        LTC294X_REG_THRESH_LOW_LSB      = 0x07,
+        LTC294X_REG_VOLTAGE_MSB = 0x08,
+        LTC294X_REG_VOLTAGE_LSB = 0x09,
+        LTC294X_REG_CURRENT_MSB = 0x0E,
+        LTC294X_REG_CURRENT_LSB = 0x0F,
+        LTC294X_REG_TEMPERATURE_MSB     = 0x14,
+        LTC294X_REG_TEMPERATURE_LSB     = 0x15,
+};
+
+#define LTC2943_REG_CONTROL_MODE_MASK (BIT(7) | BIT(6))
+#define LTC2943_REG_CONTROL_MODE_SCAN BIT(7)
+#define LTC294X_REG_CONTROL_PRESCALER_MASK      (BIT(5) | BIT(4) | BIT(3))
+#define LTC294X_REG_CONTROL_SHUTDOWN_MASK       (BIT(0))
+#define LTC294X_REG_CONTROL_PRESCALER_SET(x) \
+        ((x << 3) & LTC294X_REG_CONTROL_PRESCALER_MASK)
+#define LTC294X_REG_CONTROL_ALCC_CONFIG_DISABLED        0
+
+#define LTC2941_NUM_REGS        0x08
+#define LTC2943_NUM_REGS        0x18
+
+struct ltc294x_info {
+        struct i2c_client *client;      /* I2C Client pointer */
+        struct power_supply supply;     /* Supply pointer */
+        struct delayed_work work;       /* Work scheduler */
+        int num_regs;   /* Number of registers (chip type) */
+        int id;         /* Identifier of ltc294x chip */
+        int charge;     /* Last charge register content */
+        int r_sense;    /* mOhm */
+        int Qlsb;       /* nAh */
+};
+
+static DEFINE_IDR(ltc294x_id);
+static DEFINE_MUTEX(ltc294x_lock);
+
+static inline int convert_bin_to_uAh(
+        const struct ltc294x_info *info, int Q)
+{
+        return ((Q * (info->Qlsb / 10))) / 100;
+}
+
+static inline int convert_uAh_to_bin(
+        const struct ltc294x_info *info, int uAh)
+{
+        int Q;
+
+        Q = (uAh * 100) / (info->Qlsb/10);
+        return (Q < LTC294X_MAX_VALUE) ? Q : LTC294X_MAX_VALUE;
+}
+
+static int ltc294x_read_regs(struct i2c_client *client,
+        enum ltc294x_reg reg, u8 *buf, int num_regs)
+{
+        int ret;
+        struct i2c_msg msgs[2] = { };
+        u8 reg_start = reg;
+
+        msgs[0].addr    = client->addr;
+        msgs[0].len     = 1;
+        msgs[0].buf     = &reg_start;
+
+        msgs[1].addr    = client->addr;
+        msgs[1].len     = num_regs;
+        msgs[1].buf     = buf;
+        msgs[1].flags   = I2C_M_RD;
+
+        ret = i2c_transfer(client->adapter, &msgs[0], 2);
+        if (ret < 0) {
+                dev_err(&client->dev, "ltc2941 read_reg failed!\n");
+                return ret;
+        }
+
+        dev_dbg(&client->dev, "%s (%#x, %d) -> %#x\n",
+                __func__, reg, num_regs, *buf);
+
+        return 0;
+}
+
+static int ltc294x_write_regs(struct i2c_client *client,
+        enum ltc294x_reg reg, const u8 *buf, int num_regs)
+{
+        int ret;
+        u8 reg_start = reg;
+
+        ret = i2c_smbus_write_i2c_block_data(client, reg_start, num_regs, buf);
+        if (ret < 0) {
+                dev_err(&client->dev, "ltc2941 write_reg failed!\n");
+                return ret;
+        }
+
+        dev_dbg(&client->dev, "%s (%#x, %d) -> %#x\n",
+                __func__, reg, num_regs, *buf);
+
+        return 0;
+}
+
+static int ltc294x_reset(const struct ltc294x_info *info, int prescaler_exp)
+{
+        int ret;
+        u8 value;
+        u8 control;
+
+        /* Read status and control registers */
+        ret = ltc294x_read_regs(info->client, LTC294X_REG_CONTROL, &value, 1);
+        if (ret < 0) {
+                dev_err(&info->client->dev,
+                        "Could not read registers from device\n");
+                goto error_exit;
+        }
+
+        control = LTC294X_REG_CONTROL_PRESCALER_SET(prescaler_exp) |
+                                LTC294X_REG_CONTROL_ALCC_CONFIG_DISABLED;
+        /* Put the 2943 into "monitor" mode, so it measures every 10 sec */
+        if (info->num_regs == LTC2943_NUM_REGS)
+                control |= LTC2943_REG_CONTROL_MODE_SCAN;
+
+        if (value != control) {
+                ret = ltc294x_write_regs(info->client,
+                        LTC294X_REG_CONTROL, &control, 1);
+                if (ret < 0) {
+                        dev_err(&info->client->dev,
+                                "Could not write register\n");
+                        goto error_exit;
+                }
+        }
+
+        return 0;
+
+error_exit:
+        return ret;
+}
+
+static int ltc294x_read_charge_register(const struct ltc294x_info *info)
+{
+        int ret;
+        u8 datar[2];
+
+        ret = ltc294x_read_regs(info->client,
+                LTC294X_REG_ACC_CHARGE_MSB, &datar[0], 2);
+        if (ret < 0)
+                return ret;
+        return (datar[0] << 8) + datar[1];
+}
+
+static int ltc294x_get_charge_now(const struct ltc294x_info *info, int *val)
+{
+        int value = ltc294x_read_charge_register(info);
+
+        if (value < 0)
+                return value;
+        /* When r_sense < 0, this counts up when the battery discharges */
+        if (info->Qlsb < 0)
+                value -= 0xFFFF;
+        *val = convert_bin_to_uAh(info, value);
+        return 0;
+}
+
+static int ltc294x_set_charge_now(const struct ltc294x_info *info, int val)
+{
+        int ret;
+        u8 dataw[2];
+        u8 ctrl_reg;
+        s32 value;
+
+        value = convert_uAh_to_bin(info, val);
+        /* Direction depends on how sense+/- were connected */
+        if (info->Qlsb < 0)
+                value += 0xFFFF;
+        if ((value < 0) || (value > 0xFFFF)) /* input validation */
+                return -EINVAL;
+
+        /* Read control register */
+        ret = ltc294x_read_regs(info->client,
+                LTC294X_REG_CONTROL, &ctrl_reg, 1);
+        if (ret < 0)
+                return ret;
+        /* Disable analog section */
+        ctrl_reg |= LTC294X_REG_CONTROL_SHUTDOWN_MASK;
+        ret = ltc294x_write_regs(info->client,
+                LTC294X_REG_CONTROL, &ctrl_reg, 1);
+        if (ret < 0)
+                return ret;
+        /* Set new charge value */
+        dataw[0] = I16_MSB(value);
+        dataw[1] = I16_LSB(value);
+        ret = ltc294x_write_regs(info->client,
+                LTC294X_REG_ACC_CHARGE_MSB, &dataw[0], 2);
+        if (ret < 0)
+                goto error_exit;
+        /* Enable analog section */
+error_exit:
+        ctrl_reg &= ~LTC294X_REG_CONTROL_SHUTDOWN_MASK;
+        ret = ltc294x_write_regs(info->client,
+                LTC294X_REG_CONTROL, &ctrl_reg, 1);
+
+        return ret < 0 ? ret : 0;
+}
+
+static int ltc294x_get_charge_counter(
+        const struct ltc294x_info *info, int *val)
+{
+        int value = ltc294x_read_charge_register(info);
+
+        if (value < 0)
+                return value;
+        value -= LTC294X_MID_SUPPLY;
+        *val = convert_bin_to_uAh(info, value);
+        return 0;
+}
+
+static int ltc294x_get_voltage(const struct ltc294x_info *info, int *val)
+{
+        int ret;
+        u8 datar[2];
+        u32 value;
+
+        ret = ltc294x_read_regs(info->client,
+                LTC294X_REG_VOLTAGE_MSB, &datar[0], 2);
+        value = (datar[0] << 8) | datar[1];
+        *val = ((value * 23600) / 0xFFFF) * 1000; /* in uV */
+        return ret;
+}
+
+static int ltc294x_get_current(const struct ltc294x_info *info, int *val)
+{
+        int ret;
+        u8 datar[2];
+        s32 value;
+
+        ret = ltc294x_read_regs(info->client,
+                LTC294X_REG_CURRENT_MSB, &datar[0], 2);
+        value = (datar[0] << 8) | datar[1];
+        value -= 0x7FFF;
+        /* Value is in range -32k..+32k, r_sense is usually 10..50 mOhm,
+         * the formula below keeps everything in s32 range while preserving
+         * enough digits */
+        *val = 1000 * ((60000 * value) / (info->r_sense * 0x7FFF)); /* in uA */
+        return ret;
+}
+
+static int ltc294x_get_temperature(const struct ltc294x_info *info, int *val)
+{
+        int ret;
+        u8 datar[2];
+        u32 value;
+
+        ret = ltc294x_read_regs(info->client,
+                LTC294X_REG_TEMPERATURE_MSB, &datar[0], 2);
+        value = (datar[0] << 8) | datar[1];
+        /* Full-scale is 510 Kelvin, convert to centidegrees  */
+        *val = (((51000 * value) / 0xFFFF) - 27215);
+        return ret;
+}
+
+static int ltc294x_get_property(struct power_supply *psy,
+                                enum power_supply_property prop,
+                                union power_supply_propval *val)
+{
+        struct ltc294x_info *info =
+                container_of(psy, struct ltc294x_info, supply);
+
+        switch (prop) {
+        case POWER_SUPPLY_PROP_CHARGE_NOW:
+                return ltc294x_get_charge_now(info, &val->intval);
+        case POWER_SUPPLY_PROP_CHARGE_COUNTER:
+                return ltc294x_get_charge_counter(info, &val->intval);
+        case POWER_SUPPLY_PROP_VOLTAGE_NOW:
+                return ltc294x_get_voltage(info, &val->intval);
+        case POWER_SUPPLY_PROP_CURRENT_NOW:
+                return ltc294x_get_current(info, &val->intval);
+        case POWER_SUPPLY_PROP_TEMP:
+                return ltc294x_get_temperature(info, &val->intval);
+        default:
+                return -EINVAL;
+        }
+}
+
+static int ltc294x_set_property(struct power_supply *psy,
+        enum power_supply_property psp,
+        const union power_supply_propval *val)
+{
+        struct ltc294x_info *info =
+                container_of(psy, struct ltc294x_info, supply);
+
+        switch (psp) {
+        case POWER_SUPPLY_PROP_CHARGE_NOW:
+                return ltc294x_set_charge_now(info, val->intval);
+        default:
+                return -EPERM;
+        }
+}
+
+static int ltc294x_property_is_writeable(
+        struct power_supply *psy, enum power_supply_property psp)
+{
+        switch (psp) {
+        case POWER_SUPPLY_PROP_CHARGE_NOW:
+                return 1;
+        default:
+                return 0;
+        }
+}
+
+static void ltc294x_update(struct ltc294x_info *info)
+{
+        int charge = ltc294x_read_charge_register(info);
+
+        if (charge != info->charge) {
+                info->charge = charge;
+                power_supply_changed(&info->supply);
+        }
+}
+
+static void ltc294x_work(struct work_struct *work)
+{
+        struct ltc294x_info *info;
+
+        info = container_of(work, struct ltc294x_info, work.work);
+        ltc294x_update(info);
+        schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
+}
+
+static enum power_supply_property ltc294x_properties[] = {
+        POWER_SUPPLY_PROP_CHARGE_COUNTER,
+        POWER_SUPPLY_PROP_CHARGE_NOW,
+        POWER_SUPPLY_PROP_VOLTAGE_NOW,
+        POWER_SUPPLY_PROP_CURRENT_NOW,
+        POWER_SUPPLY_PROP_TEMP,
+};
+
+static int ltc294x_i2c_remove(struct i2c_client *client)
+{
+        struct ltc294x_info *info = i2c_get_clientdata(client);
+
+        cancel_delayed_work(&info->work);
+        power_supply_unregister(&info->supply);
+        kfree(info->supply.name);
+        mutex_lock(&ltc294x_lock);
+        idr_remove(&ltc294x_id, info->id);
+        mutex_unlock(&ltc294x_lock);
+        return 0;
+}
+
+static int ltc294x_i2c_probe(struct i2c_client *client,
+        const struct i2c_device_id *id)
+{
+        struct ltc294x_info *info;
+        int ret;
+        int num;
+        u32 prescaler_exp;
+        s32 r_sense;
+        struct device_node *np;
+
+        mutex_lock(&ltc294x_lock);
+        ret = idr_alloc(&ltc294x_id, client, 0, 0, GFP_KERNEL);
+        mutex_unlock(&ltc294x_lock);
+        if (ret < 0)
+                goto fail_id;
+
+        num = ret;
+
+        info = devm_kzalloc(&client->dev, sizeof(*info), GFP_KERNEL);
+        if (info == NULL) {
+                ret = -ENOMEM;
+                goto fail_info;
+        }
+
+        i2c_set_clientdata(client, info);
+
+        info->num_regs = id->driver_data;
+        info->supply.name = kasprintf(GFP_KERNEL, "%s-%d", client->name, num);
+        if (!info->supply.name) {
+                ret = -ENOMEM;
+                goto fail_name;
+        }
+
+        np = of_node_get(client->dev.of_node);
+
+        /* r_sense can be negative, when sense+ is connected to the battery
+         * instead of the sense-. This results in reversed measurements. */
+        ret = of_property_read_u32(np, "lltc,resistor-sense", &r_sense);
+        if (ret < 0) {
+                dev_err(&client->dev,
+                        "Could not find lltc,resistor-sense in devicetree\n");
+                goto fail_name;
+        }
+        info->r_sense = r_sense;
+
+        ret = of_property_read_u32(np, "lltc,prescaler-exponent",
+                &prescaler_exp);
+        if (ret < 0) {
+                dev_warn(&client->dev,
+                        "lltc,prescaler-exponent not in devicetree\n");
+                prescaler_exp = LTC2941_MAX_PRESCALER_EXP;
+        }
+
+        if (info->num_regs == LTC2943_NUM_REGS) {
+                if (prescaler_exp > LTC2943_MAX_PRESCALER_EXP)
+                        prescaler_exp = LTC2943_MAX_PRESCALER_EXP;
+                info->Qlsb = ((340 * 50000) / r_sense) /
+                                (4096 / (1 << (2*prescaler_exp)));
+        } else {
+                if (prescaler_exp > LTC2941_MAX_PRESCALER_EXP)
+                        prescaler_exp = LTC2941_MAX_PRESCALER_EXP;
+                info->Qlsb = ((58 * 50000) / r_sense) /
+                                (128 / (1 << prescaler_exp));
+        }
+
+        info->client = client;
+        info->id = num;
+        info->supply.type = POWER_SUPPLY_TYPE_BATTERY;
+        info->supply.properties = ltc294x_properties;
+        if (info->num_regs >= LTC294X_REG_TEMPERATURE_LSB)
+                info->supply.num_properties =
+                        ARRAY_SIZE(ltc294x_properties);
+        else if (info->num_regs >= LTC294X_REG_CURRENT_LSB)
+                info->supply.num_properties =
+                        ARRAY_SIZE(ltc294x_properties) - 1;
+        else if (info->num_regs >= LTC294X_REG_VOLTAGE_LSB)
+                info->supply.num_properties =
+                        ARRAY_SIZE(ltc294x_properties) - 2;
+        else
+                info->supply.num_properties =
+                        ARRAY_SIZE(ltc294x_properties) - 3;
+        info->supply.get_property = ltc294x_get_property;
+        info->supply.set_property = ltc294x_set_property;
+        info->supply.property_is_writeable = ltc294x_property_is_writeable;
+        info->supply.external_power_changed     = NULL;
+
+        INIT_DELAYED_WORK(&info->work, ltc294x_work);
+
+        ret = ltc294x_reset(info, prescaler_exp);
+        if (ret < 0) {
+                dev_err(&client->dev, "Communication with chip failed\n");
+                goto fail_comm;
+        }
+
+        ret = power_supply_register(&client->dev, &info->supply);
+        if (ret) {
+                dev_err(&client->dev, "failed to register ltc2941\n");
+                goto fail_register;
+        } else {
+                schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
+        }
+
+        return 0;
+
+fail_register:
+        kfree(info->supply.name);
+fail_comm:
+fail_name:
+fail_info:
+        mutex_lock(&ltc294x_lock);
+        idr_remove(&ltc294x_id, num);
+        mutex_unlock(&ltc294x_lock);
+fail_id:
+        return ret;
+}
+
+#ifdef CONFIG_PM_SLEEP
+
+static int ltc294x_suspend(struct device *dev)
+{
+        struct i2c_client *client = to_i2c_client(dev);
+        struct ltc294x_info *info = i2c_get_clientdata(client);
+
+        cancel_delayed_work(&info->work);
+        return 0;
+}
+
+static int ltc294x_resume(struct device *dev)
+{
+        struct i2c_client *client = to_i2c_client(dev);
+        struct ltc294x_info *info = i2c_get_clientdata(client);
+
+        schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ);
+        return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(ltc294x_pm_ops, ltc294x_suspend, ltc294x_resume);
+#define LTC294X_PM_OPS (&ltc294x_pm_ops)
+
+#else
+#define LTC294X_PM_OPS NULL
+#endif /* CONFIG_PM_SLEEP */
+
+
+static const struct i2c_device_id ltc294x_i2c_id[] = {
+        {"ltc2941", LTC2941_NUM_REGS},
+        {"ltc2943", LTC2943_NUM_REGS},
+        { },
+};
+MODULE_DEVICE_TABLE(i2c, ltc294x_i2c_id);
+
+static struct i2c_driver ltc294x_driver = {
+        .driver = {
+                .name   = "LTC2941",
+                .pm     = LTC294X_PM_OPS,
+        },
+        .probe          = ltc294x_i2c_probe,
+        .remove         = ltc294x_i2c_remove,
+        .id_table       = ltc294x_i2c_id,
+};
+module_i2c_driver(ltc294x_driver);
+
+MODULE_AUTHOR("Auryn Verwegen, Topic Embedded Systems");
+MODULE_AUTHOR("Mike Looijmans, Topic Embedded Products");
+MODULE_DESCRIPTION("LTC2941/LTC2943 Battery Gas Gauge IC driver");
+MODULE_LICENSE("GPL");