diff options
Diffstat (limited to 'drivers/power/ltc2941-battery-gauge.c')
| -rw-r--r-- | drivers/power/ltc2941-battery-gauge.c | 547 |
1 files changed, 547 insertions, 0 deletions
diff --git a/drivers/power/ltc2941-battery-gauge.c b/drivers/power/ltc2941-battery-gauge.c new file mode 100644 index 00000000000..e31c927a6d1 --- /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 = ®_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(<c294x_lock); + idr_remove(<c294x_id, info->id); + mutex_unlock(<c294x_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(<c294x_lock); + ret = idr_alloc(<c294x_id, client, 0, 0, GFP_KERNEL); + mutex_unlock(<c294x_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(<c294x_lock); + idr_remove(<c294x_id, num); + mutex_unlock(<c294x_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 (<c294x_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"); |