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/*
* 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 :
|