/* * 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/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 power_supply_desc supply_desc; /* Supply description */ struct delayed_work work; /* Work scheduler */ int num_regs; /* Number of registers (chip type) */ int charge; /* Last charge register content */ int r_sense; /* mOhm */ int Qlsb; /* nAh */ }; 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 = power_supply_get_drvdata(psy); 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 = power_supply_get_drvdata(psy); 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); return 0; } static int ltc294x_i2c_probe(struct i2c_client *client, const struct i2c_device_id *id) { struct power_supply_config psy_cfg = {}; struct ltc294x_info *info; int ret; u32 prescaler_exp; s32 r_sense; struct device_node *np; info = devm_kzalloc(&client->dev, sizeof(*info), GFP_KERNEL); if (info == NULL) return -ENOMEM; i2c_set_clientdata(client, info); np = of_node_get(client->dev.of_node); info->num_regs = id->driver_data; info->supply_desc.name = np->name; /* 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"); return ret; } 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 = ((85 * 50000) / r_sense) / (128 / (1 << prescaler_exp)); } info->client = client; info->supply_desc.type = POWER_SUPPLY_TYPE_BATTERY; info->supply_desc.properties = ltc294x_properties; if (info->num_regs >= LTC294X_REG_TEMPERATURE_LSB) info->supply_desc.num_properties = ARRAY_SIZE(ltc294x_properties); else if (info->num_regs >= LTC294X_REG_CURRENT_LSB) info->supply_desc.num_properties = ARRAY_SIZE(ltc294x_properties) - 1; else if (info->num_regs >= LTC294X_REG_VOLTAGE_LSB) info->supply_desc.num_properties = ARRAY_SIZE(ltc294x_properties) - 2; else info->supply_desc.num_properties = ARRAY_SIZE(ltc294x_properties) - 3; info->supply_desc.get_property = ltc294x_get_property; info->supply_desc.set_property = ltc294x_set_property; info->supply_desc.property_is_writeable = ltc294x_property_is_writeable; info->supply_desc.external_power_changed = NULL; psy_cfg.drv_data = info; 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"); return ret; } info->supply = power_supply_register(&client->dev, &info->supply_desc, &psy_cfg); if (IS_ERR(info->supply)) { dev_err(&client->dev, "failed to register ltc2941\n"); return PTR_ERR(info->supply); } else { schedule_delayed_work(&info->work, LTC294X_WORK_DELAY * HZ); } return 0; } #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");