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/*
* Driver for batteries with DS2760 chips inside.
*
* Copyright © 2007 Anton Vorontsov
* 2004-2007 Matt Reimer
* 2004 Szabolcs Gyurko
*
* Use consistent with the GNU GPL is permitted,
* provided that this copyright notice is
* preserved in its entirety in all copies and derived works.
*
* Author: Anton Vorontsov <cbou@mail.ru>
* February 2007
*
* Matt Reimer <mreimer@vpop.net>
* April 2004, 2005, 2007
*
* Szabolcs Gyurko <szabolcs.gyurko@tlt.hu>
* September 2004
*/
#include <linux/module.h>
#include <linux/param.h>
#include <linux/jiffies.h>
#include <linux/workqueue.h>
#include <linux/pm.h>
#include <linux/platform_device.h>
#include <linux/power_supply.h>
#include "../w1/w1.h"
#include "../w1/slaves/w1_ds2760.h"
struct ds2760_device_info {
struct device *dev;
/* DS2760 data, valid after calling ds2760_battery_read_status() */
unsigned long update_time; /* jiffies when data read */
char raw[DS2760_DATA_SIZE]; /* raw DS2760 data */
int voltage_raw; /* units of 4.88 mV */
int voltage_uV; /* units of µV */
int current_raw; /* units of 0.625 mA */
int current_uA; /* units of µA */
int accum_current_raw; /* units of 0.25 mAh */
int accum_current_uAh; /* units of µAh */
int temp_raw; /* units of 0.125 °C */
int temp_C; /* units of 0.1 °C */
int rated_capacity; /* units of µAh */
int rem_capacity; /* percentage */
int full_active_uAh; /* units of µAh */
int empty_uAh; /* units of µAh */
int life_sec; /* units of seconds */
int charge_status; /* POWER_SUPPLY_STATUS_* */
int full_counter;
struct power_supply bat;
struct device *w1_dev;
struct workqueue_struct *monitor_wqueue;
struct delayed_work monitor_work;
};
static unsigned int cache_time = 1000;
module_param(cache_time, uint, 0644);
MODULE_PARM_DESC(cache_time, "cache time in milliseconds");
static unsigned int pmod_enabled;
module_param(pmod_enabled, bool, 0644);
MODULE_PARM_DESC(pmod_enabled, "PMOD enable bit");
static unsigned int rated_capacity;
module_param(rated_capacity, uint, 0644);
MODULE_PARM_DESC(rated_capacity, "rated battery capacity, 10*mAh or index");
/* Some batteries have their rated capacity stored a N * 10 mAh, while
* others use an index into this table. */
static int rated_capacities[] = {
0,
920, /* Samsung */
920, /* BYD */
920, /* Lishen */
920, /* NEC */
1440, /* Samsung */
1440, /* BYD */
1440, /* Lishen */
1440, /* NEC */
2880, /* Samsung */
2880, /* BYD */
2880, /* Lishen */
2880 /* NEC */
};
/* array is level at temps 0°C, 10°C, 20°C, 30°C, 40°C
* temp is in Celsius */
static int battery_interpolate(int array[], int temp)
{
int index, dt;
if (temp <= 0)
return array[0];
if (temp >= 40)
return array[4];
index = temp / 10;
dt = temp % 10;
return array[index] + (((array[index + 1] - array[index]) * dt) / 10);
}
static int ds2760_battery_read_status(struct ds2760_device_info *di)
{
int ret, i, start, count, scale[5];
if (di->update_time && time_before(jiffies, di->update_time +
msecs_to_jiffies(cache_time)))
return 0;
/* The first time we read the entire contents of SRAM/EEPROM,
* but after that we just read the interesting bits that change. */
if (di->update_time == 0) {
start = 0;
count = DS2760_DATA_SIZE;
} else {
start = DS2760_VOLTAGE_MSB;
count = DS2760_TEMP_LSB - start + 1;
}
ret = w1_ds2760_read(di->w1_dev, di->raw + start, start, count);
if (ret != count) {
dev_warn(di->dev, "call to w1_ds2760_read failed (0x%p)\n",
di->w1_dev);
return 1;
}
di->update_time = jiffies;
/* DS2760 reports voltage in units of 4.88mV, but the battery class
* reports in units of uV, so convert by multiplying by 4880. */
di->voltage_raw = (di->raw[DS2760_VOLTAGE_MSB] << 3) |
(di->raw[DS2760_VOLTAGE_LSB] >> 5);
di->voltage_uV = di->voltage_raw * 4880;
/* DS2760 reports current in signed units of 0.625mA, but the battery
* class reports in units of µA, so convert by multiplying by 625. */
di->current_raw =
(((signed char)di->raw[DS2760_CURRENT_MSB]) << 5) |
(di->raw[DS2760_CURRENT_LSB] >> 3);
di->current_uA = di->current_raw * 625;
/* DS2760 reports accumulated current in signed units of 0.25mAh. */
di->accum_current_raw =
(((signed char)di->raw[DS2760_CURRENT_ACCUM_MSB]) << 8) |
di->raw[DS2760_CURRENT_ACCUM_LSB];
di->accum_current_uAh = di->accum_current_raw * 250;
/* DS2760 reports temperature in signed units of 0.125°C, but the
* battery class reports in units of 1/10 °C, so we convert by
* multiplying by .125 * 10 = 1.25. */
di->temp_raw = (((signed char)di->raw[DS2760_TEMP_MSB]) << 3) |
(di->raw[DS2760_TEMP_LSB] >> 5);
di->temp_C = di->temp_raw + (di->temp_raw / 4);
/* At least some battery monitors (e.g. HP iPAQ) store the battery's
* maximum rated capacity. */
if (di->raw[DS2760_RATED_CAPACITY] < ARRAY_SIZE(rated_capacities))
di->rated_capacity = rated_capacities[
(unsigned int)di->raw[DS2760_RATED_CAPACITY]];
else
di->rated_capacity = di->raw[DS2760_RATED_CAPACITY] * 10;
di->rated_capacity *= 1000; /* convert to µAh */
/* Calculate the full level at the present temperature. */
di->full_active_uAh = di->raw[DS2760_ACTIVE_FULL] << 8 |
di->raw[DS2760_ACTIVE_FULL + 1];
scale[0] = di->raw[DS2760_ACTIVE_FULL] << 8 |
di->raw[DS2760_ACTIVE_FULL + 1];
for (i = 1; i < 5; i++)
scale[i] = scale[i - 1] + di->raw[DS2760_ACTIVE_FULL + 2 + i];
di->full_active_uAh = battery_interpolate(scale, di->temp_C / 10);
di->full_active_uAh *= 1000; /* convert to µAh */
/* Calculate the empty level at the present temperature. */
scale[4] = di->raw[DS2760_ACTIVE_EMPTY + 4];
for (i = 3; i >= 0; i--)
scale[i] = scale[i + 1] + di->raw[DS2760_ACTIVE_EMPTY + i];
di->empty_uAh = battery_interpolate(scale, di->temp_C / 10);
di->empty_uAh *= 1000; /* convert to µAh */
if (di->full_active_uAh == di->empty_uAh)
di->rem_capacity = 0;
else
/* From Maxim Application Note 131: remaining capacity =
* ((ICA - Empty Value) / (Full Value - Empty Value)) x 100% */
di->rem_capacity = ((di->accum_current_uAh - di->empty_uAh) * 100L) /
(di->full_active_uAh - di->empty_uAh);
if (di->rem_capacity < 0)
di->rem_capacity = 0;
if (di->rem_capacity > 100)
di->rem_capacity = 100;
if (di->current_uA)
di->life_sec = -((di->accum_current_uAh - di->empty_uAh) *
3600L) / di->current_uA;
else
di->life_sec = 0;
return 0;
}
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