linux/drivers/power/supply/ab8500_bmdata.c
Linus Walleij 1f918e0fe4 power: supply: ab8500: Standardize BTI resistance
The Battery Type Indicator (BTI) resistor is a resistor mounted
between a special terminal on the battery and ground. By sending
a fixed current (such as 7mA) through this resistor and measuring
the voltage over it, the resistance can be determined, and this
verifies the battery type.

Typical side view of the battery:

  o     o     o
 GND   BTI   +3.8V

Typical example of the electrical layout:

  +3.8 V   BTI
    |       |
    | +     |
 _______   [ ] 7kOhm
   ___      |
    |       |
    |       |
   GND     GND

By verifying this resistance before attempting to charge the
battery we add an additional level of security.

In some systems this is used for plug-and-play of batteries with
different capacity. In other cases, this is merely used to verify
that the right type of battery is connected, if several batteries
have the same physical shape and can be plugged into the same
slot. Sometimes this is just a surplus security mechanism.

Nokia and Samsung among many other vendors are known to use these
BTI resistors.

Add the BTI properties to struct power_supply_battery_info and
switch the AB8500 charger code over to using it.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
2022-02-28 11:34:31 +01:00

242 lines
7.2 KiB
C

// SPDX-License-Identifier: GPL-2.0
#include <linux/export.h>
#include <linux/power_supply.h>
#include <linux/of.h>
#include "ab8500-bm.h"
/* Default: under this temperature, charging is stopped */
#define AB8500_TEMP_UNDER 3
/* Default: between this temp and AB8500_TEMP_UNDER charging is reduced */
#define AB8500_TEMP_LOW 8
/* Default: between this temp and AB8500_TEMP_OVER charging is reduced */
#define AB8500_TEMP_HIGH 43
/* Default: over this temp, charging is stopped */
#define AB8500_TEMP_OVER 48
/* Default: temperature hysteresis */
#define AB8500_TEMP_HYSTERESIS 3
static struct power_supply_battery_ocv_table ocv_cap_tbl[] = {
{ .ocv = 4186000, .capacity = 100},
{ .ocv = 4163000, .capacity = 99},
{ .ocv = 4114000, .capacity = 95},
{ .ocv = 4068000, .capacity = 90},
{ .ocv = 3990000, .capacity = 80},
{ .ocv = 3926000, .capacity = 70},
{ .ocv = 3898000, .capacity = 65},
{ .ocv = 3866000, .capacity = 60},
{ .ocv = 3833000, .capacity = 55},
{ .ocv = 3812000, .capacity = 50},
{ .ocv = 3787000, .capacity = 40},
{ .ocv = 3768000, .capacity = 30},
{ .ocv = 3747000, .capacity = 25},
{ .ocv = 3730000, .capacity = 20},
{ .ocv = 3705000, .capacity = 15},
{ .ocv = 3699000, .capacity = 14},
{ .ocv = 3684000, .capacity = 12},
{ .ocv = 3672000, .capacity = 9},
{ .ocv = 3657000, .capacity = 7},
{ .ocv = 3638000, .capacity = 6},
{ .ocv = 3556000, .capacity = 4},
{ .ocv = 3424000, .capacity = 2},
{ .ocv = 3317000, .capacity = 1},
{ .ocv = 3094000, .capacity = 0},
};
/*
* Note that the batres_vs_temp table must be strictly sorted by falling
* temperature values to work. Factory resistance is 300 mOhm and the
* resistance values to the right are percentages of 300 mOhm.
*/
static struct power_supply_resistance_temp_table temp_to_batres_tbl_thermistor[] = {
{ .temp = 40, .resistance = 40 /* 120 mOhm */ },
{ .temp = 30, .resistance = 45 /* 135 mOhm */ },
{ .temp = 20, .resistance = 55 /* 165 mOhm */ },
{ .temp = 10, .resistance = 77 /* 230 mOhm */ },
{ .temp = 00, .resistance = 108 /* 325 mOhm */ },
{ .temp = -10, .resistance = 158 /* 445 mOhm */ },
{ .temp = -20, .resistance = 198 /* 595 mOhm */ },
};
static struct power_supply_maintenance_charge_table ab8500_maint_charg_table[] = {
{
/* Maintenance charging phase A, 60 hours */
.charge_current_max_ua = 400000,
.charge_voltage_max_uv = 4050000,
.charge_safety_timer_minutes = 60*60,
},
{
/* Maintenance charging phase B, 200 hours */
.charge_current_max_ua = 400000,
.charge_voltage_max_uv = 4000000,
.charge_safety_timer_minutes = 200*60,
}
};
static const struct ab8500_bm_capacity_levels cap_levels = {
.critical = 2,
.low = 10,
.normal = 70,
.high = 95,
.full = 100,
};
static const struct ab8500_fg_parameters fg = {
.recovery_sleep_timer = 10,
.recovery_total_time = 100,
.init_timer = 1,
.init_discard_time = 5,
.init_total_time = 40,
.high_curr_time = 60,
.accu_charging = 30,
.accu_high_curr = 30,
.high_curr_threshold_ua = 50000,
.lowbat_threshold_uv = 3100000,
.battok_falling_th_sel0 = 2860,
.battok_raising_th_sel1 = 2860,
.maint_thres = 95,
.user_cap_limit = 15,
.pcut_enable = 1,
.pcut_max_time = 127,
.pcut_flag_time = 112,
.pcut_max_restart = 15,
.pcut_debounce_time = 2,
};
static const struct ab8500_maxim_parameters ab8500_maxi_params = {
.ena_maxi = true,
.chg_curr_ua = 910000,
.wait_cycles = 10,
.charger_curr_step_ua = 100000,
};
static const struct ab8500_bm_charger_parameters chg = {
.usb_volt_max_uv = 5500000,
.usb_curr_max_ua = 1500000,
.ac_volt_max_uv = 7500000,
.ac_curr_max_ua = 1500000,
};
/* This is referenced directly in the charger code */
struct ab8500_bm_data ab8500_bm_data = {
.main_safety_tmr_h = 4,
.temp_interval_chg = 20,
.temp_interval_nochg = 120,
.usb_safety_tmr_h = 4,
.bkup_bat_v = BUP_VCH_SEL_2P6V,
.bkup_bat_i = BUP_ICH_SEL_150UA,
.capacity_scaling = false,
.chg_unknown_bat = false,
.enable_overshoot = false,
.fg_res = 100,
.cap_levels = &cap_levels,
.interval_charging = 5,
.interval_not_charging = 120,
.maxi = &ab8500_maxi_params,
.chg_params = &chg,
.fg_params = &fg,
};
int ab8500_bm_of_probe(struct power_supply *psy,
struct ab8500_bm_data *bm)
{
struct power_supply_battery_info *bi;
struct device *dev = &psy->dev;
int ret;
ret = power_supply_get_battery_info(psy, &bm->bi);
if (ret) {
dev_err(dev, "cannot retrieve battery info\n");
return ret;
}
bi = bm->bi;
/* Fill in defaults for any data missing from the device tree */
if (bi->charge_full_design_uah < 0)
/* The default capacity is 612 mAh for unknown batteries */
bi->charge_full_design_uah = 612000;
/*
* All of these voltages need to be specified or we will simply
* fall back to safe defaults.
*/
if ((bi->voltage_min_design_uv < 0) ||
(bi->voltage_max_design_uv < 0)) {
/* Nominal voltage is 3.7V for unknown batteries */
bi->voltage_min_design_uv = 3700000;
/* Termination voltage 4.05V */
bi->voltage_max_design_uv = 4050000;
}
if (bi->constant_charge_current_max_ua < 0)
bi->constant_charge_current_max_ua = 400000;
if (bi->constant_charge_voltage_max_uv < 0)
bi->constant_charge_voltage_max_uv = 4100000;
if (bi->charge_term_current_ua)
/* Charging stops when we drop below this current */
bi->charge_term_current_ua = 200000;
if (!bi->maintenance_charge || !bi->maintenance_charge_size) {
bi->maintenance_charge = ab8500_maint_charg_table;
bi->maintenance_charge_size = ARRAY_SIZE(ab8500_maint_charg_table);
}
if (bi->alert_low_temp_charge_current_ua < 0 ||
bi->alert_low_temp_charge_voltage_uv < 0)
{
bi->alert_low_temp_charge_current_ua = 300000;
bi->alert_low_temp_charge_voltage_uv = 4000000;
}
if (bi->alert_high_temp_charge_current_ua < 0 ||
bi->alert_high_temp_charge_voltage_uv < 0)
{
bi->alert_high_temp_charge_current_ua = 300000;
bi->alert_high_temp_charge_voltage_uv = 4000000;
}
/*
* Internal resistance and factory resistance are tightly coupled
* so both MUST be defined or we fall back to defaults.
*/
if ((bi->factory_internal_resistance_uohm < 0) ||
!bi->resist_table) {
bi->factory_internal_resistance_uohm = 300000;
bi->resist_table = temp_to_batres_tbl_thermistor;
bi->resist_table_size = ARRAY_SIZE(temp_to_batres_tbl_thermistor);
}
/* The default battery is emulated by a resistor at 7K */
if (bi->bti_resistance_ohm < 0 ||
bi->bti_resistance_tolerance < 0) {
bi->bti_resistance_ohm = 7000;
bi->bti_resistance_tolerance = 20;
}
if (!bi->ocv_table[0]) {
/* Default capacity table at say 25 degrees Celsius */
bi->ocv_temp[0] = 25;
bi->ocv_table[0] = ocv_cap_tbl;
bi->ocv_table_size[0] = ARRAY_SIZE(ocv_cap_tbl);
}
if (bi->temp_min == INT_MIN)
bi->temp_min = AB8500_TEMP_UNDER;
if (bi->temp_max == INT_MAX)
bi->temp_max = AB8500_TEMP_OVER;
if (bi->temp_alert_min == INT_MIN)
bi->temp_alert_min = AB8500_TEMP_LOW;
if (bi->temp_alert_max == INT_MAX)
bi->temp_alert_max = AB8500_TEMP_HIGH;
bm->temp_hysteresis = AB8500_TEMP_HYSTERESIS;
return 0;
}
void ab8500_bm_of_remove(struct power_supply *psy,
struct ab8500_bm_data *bm)
{
power_supply_put_battery_info(psy, bm->bi);
}