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SubjectRe: [PATCH 3/4] power_supply: Introduce PSE compliant algorithm
Hi Jenny,

On Mon, Jun 30, 2014 at 03:25:54PM +0530, Jenny TC wrote:
> As per Product Safety Engineering (PSE) specification for battery charging, the
> battery characteristics and thereby the charging rates can vary on different
> temperature zones. This patch introduces a PSE compliant charging algorithm with
> maintenance charging support. The algorithm can be selected by the power supply
> charging driver based on the type of the battery charging profile.
>
> Signed-off-by: Jenny TC <jenny.tc@intel.com>

Code looks quite good. I have a couple of minor nits:

> ---
> drivers/power/Kconfig | 15 +++
> drivers/power/Makefile | 1 +
> drivers/power/charging_algo_pse.c | 202 ++++++++++++++++++++++++++++
> include/linux/power/power_supply_charger.h | 63 +++++++++
> 4 files changed, 281 insertions(+)
> create mode 100644 drivers/power/charging_algo_pse.c
>
> diff --git a/drivers/power/Kconfig b/drivers/power/Kconfig
> index f679f82..54a0321 100644
> --- a/drivers/power/Kconfig
> +++ b/drivers/power/Kconfig
> @@ -22,6 +22,21 @@ config POWER_SUPPLY_CHARGER
> drivers to keep the charging logic outside and the charger driver
> just need to abstract the charger hardware.
>
> +config POWER_SUPPLY_CHARGING_ALGO_PSE
> + bool "PSE compliant charging algorithm"
> + depends on POWER_SUPPLY_CHARGER
> + help
> + Say Y here to select Product Safety Engineering (PSE) compliant
> + charging algorithm. As per PSE standard the battery characteristics
> + and thereby the charging rates can vary on different temperature
> + zones. Select this if your charging algorithm need to change the
> + charging parameters based on the battery temperature and the battery
> + charging profile follows the struct psy_pse_chrg_prof definition.
> + This config will enable PSE compliant charging algorithm with
> + maintenance charging support. At runtime the algorithm will be
> + selected by the psy charger driver based on the type of the battery
> + charging profile.
> +
> config PDA_POWER
> tristate "Generic PDA/phone power driver"
> depends on !S390
> diff --git a/drivers/power/Makefile b/drivers/power/Makefile
> index 405f0f4..77535fd 100644
> --- a/drivers/power/Makefile
> +++ b/drivers/power/Makefile
> @@ -8,6 +8,7 @@ obj-$(CONFIG_POWER_SUPPLY) += power_supply.o
> obj-$(CONFIG_GENERIC_ADC_BATTERY) += generic-adc-battery.o
>
> obj-$(CONFIG_POWER_SUPPLY_CHARGER) += power_supply_charger.o
> +obj-$(CONFIG_POWER_SUPPLY_CHARGING_ALGO_PSE) += charging_algo_pse.o
> obj-$(CONFIG_PDA_POWER) += pda_power.o
> obj-$(CONFIG_APM_POWER) += apm_power.o
> obj-$(CONFIG_MAX8925_POWER) += max8925_power.o
> diff --git a/drivers/power/charging_algo_pse.c b/drivers/power/charging_algo_pse.c
> new file mode 100644
> index 0000000..6ec4873
> --- /dev/null
> +++ b/drivers/power/charging_algo_pse.c
> @@ -0,0 +1,202 @@
> +/*
> + * Copyright (C) 2012 Intel Corporation
> + *
> + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; version 2 of the License.
> + *
> + * This program is distributed in the hope that it will be useful, but
> + * WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
> + * General Public License for more details.
> + *
> + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> + * Author: Jenny TC <jenny.tc@intel.com>
> + */
> +
> +#include <linux/module.h>
> +#include <linux/types.h>
> +#include <linux/init.h>
> +#include <linux/slab.h>
> +#include <linux/device.h>
> +#include <linux/err.h>
> +#include <linux/power_supply.h>
> +#include <linux/thermal.h>
> +#include "power_supply.h"
> +#include "power_supply_charger.h"
> +
> +/* 98% of CV is considered as voltage to detect Full */
> +#define FULL_CV_MIN 98
> +
> +/*
> + * Offset to exit from maintenance charging. In maintenance charging
> + * if the volatge is less than the (maintenance_lower_threshold -
> + * MAINT_EXIT_OFFSET) then system can switch to normal charging
> + */
> +
> +#define MAINT_EXIT_OFFSET 50 /* mV */
> +
> +static int get_tempzone(struct psy_pse_chrg_prof *pse_mod_bprof,
> + int temp)
> +{
> + int i = 0;
> + int temp_range_cnt;
> +
> + temp_range_cnt = min_t(u16, pse_mod_bprof->temp_mon_ranges,
> + BATT_TEMP_NR_RNG);
> + if ((temp < pse_mod_bprof->temp_low_lim) ||
> + (temp > pse_mod_bprof->temp_mon_range[0].temp_up_lim))
> + return -EINVAL;
> +
> + for (i = 0; i < temp_range_cnt; ++i)
> + if (temp > pse_mod_bprof->temp_mon_range[i].temp_up_lim)
> + break;
> + return i-1;
> +}

pse_mod_bprof->temp_mon_ranges > BATT_TEMP_NR_RNG is not allowed,
so I suggest to print an error and return some error code.

> +static inline bool is_charge_terminated(long volt, long cur,
> + long iterm, unsigned long cv)
> +{
> + return (cur > 0) && (cur <= iterm) &&
> + ((volt * 100) >= (FULL_CV_MIN * cv));
> +}
> +
> +static inline bool is_battery_full(struct psy_batt_context *batt_cxt,
> + struct psy_pse_chrg_prof *pse_mod_bprof, unsigned long cv)
> +{
> + int i;
> + struct psy_batt_props batt_props;
> +
> + batt_props = batt_cxt->batt_props;
> +
> + /*
> + * Software full detection. Check the battery charge current to detect
> + * battery Full. The voltage also verified to avoid false charge
> + * full detection.
> + */
> + for (i = (MAX_CUR_VOLT_SAMPLES - 1); i >= 0; --i) {
> +
> + if (!(is_charge_terminated(batt_cxt->voltage_now_cache[i],
> + batt_cxt->current_now_cache[i],
> + pse_mod_bprof->chrg_term_mA, cv)))
> + return false;
> + }
> +
> + return true;
> +}
> +
> +static int pse_get_bat_thresholds(struct psy_batt_chrg_prof bprof,
> + struct psy_batt_thresholds *bat_thresh)
> +{
> + struct psy_pse_chrg_prof *pse_mod_bprof =
> + (struct psy_pse_chrg_prof *) bprof.batt_prof;
> +
> + if ((bprof.chrg_prof_type != PSY_CHRG_PROF_PSE) || (!pse_mod_bprof))
> + return -EINVAL;
> +
> + bat_thresh->iterm = pse_mod_bprof->chrg_term_mA;
> + bat_thresh->temp_min = pse_mod_bprof->temp_low_lim;
> + bat_thresh->temp_max = pse_mod_bprof->temp_mon_range[0].temp_up_lim;
> +
> + return 0;
> +}
> +
> +static enum psy_algo_stat pse_get_next_cc_cv(struct psy_batt_context *batt_cxt,
> + struct psy_batt_chrg_prof bprof, unsigned long *cc, unsigned long *cv)
> +{
> + int tzone;
> + struct psy_pse_chrg_prof *pse_mod_bprof;
> + struct psy_batt_props batt_props;
> + enum psy_algo_stat algo_stat;
> + int maint_exit_volt;
> +
> + pse_mod_bprof = (struct psy_pse_chrg_prof *) bprof.batt_prof;
> + algo_stat = batt_cxt->algo_stat;
> +
> + batt_props = batt_cxt->batt_props;
> +
> + *cc = *cv = 0;
> +
> + /*
> + * If STATUS is discharging, assume that charger is not connected.
> + * If charger is not connected, no need to take any action.
> + * If charge profile type is not PSY_CHRG_PROF_PSE or the charge profile
> + * is not present, no need to take any action.
> + */
> +
> + if (!pse_mod_bprof)
> + return PSY_ALGO_STAT_NOT_CHARGE;
> +
> + tzone = get_tempzone(pse_mod_bprof, batt_props.temperature);
> +
> + if (tzone < 0)
> + return PSY_ALGO_STAT_NOT_CHARGE;
> +
> + /*
> + * Change the algo status to not charging, if battery is
> + * not really charging or less than maintenance exit threshold.
> + * This way algorithm can switch to normal charging if current
> + * status is full/maintenance.
> + */
> + maint_exit_volt = pse_mod_bprof->
> + temp_mon_range[tzone].maint_chrg_vol_ll -
> + MAINT_EXIT_OFFSET;
> +
> + if ((batt_props.status == POWER_SUPPLY_STATUS_DISCHARGING) ||
> + (batt_props.status == POWER_SUPPLY_STATUS_NOT_CHARGING) ||
> + batt_props.voltage_now < maint_exit_volt) {
> +
> + algo_stat = PSY_ALGO_STAT_NOT_CHARGE;
> +
> + }
> +
> + /* read cc and cv based on temperature and algorithm status */
> + if (algo_stat == PSY_ALGO_STAT_FULL ||
> + algo_stat == PSY_ALGO_STAT_MAINT) {
> +
> + /*
> + * if status is full and voltage is lower than maintenance lower
> + * threshold change status to maintenance
> + */
> +
> + if (algo_stat == PSY_ALGO_STAT_FULL &&
> + (batt_props.voltage_now <=
> + pse_mod_bprof->temp_mon_range[tzone].maint_chrg_vol_ll))
> + algo_stat = PSY_ALGO_STAT_MAINT;
> +
> + /* Read maintenance CC and CV */
> + if (algo_stat == PSY_ALGO_STAT_MAINT) {
> + *cv = pse_mod_bprof->temp_mon_range
> + [tzone].maint_chrg_vol_ul;
> + *cc = pse_mod_bprof->temp_mon_range
> + [tzone].maint_chrg_cur;
> + }
> + } else {
> + *cv = pse_mod_bprof->temp_mon_range[tzone].full_chrg_vol;
> + *cc = pse_mod_bprof->temp_mon_range[tzone].full_chrg_cur;
> + algo_stat = PSY_ALGO_STAT_CHARGE;
> + }
> +
> + if (is_battery_full(batt_cxt, pse_mod_bprof, *cv)) {
> + *cc = *cv = 0;
> + algo_stat = PSY_ALGO_STAT_FULL;
> + }
> +
> + return algo_stat;
> +}
> +
> +struct psy_charging_algo pse_algo = {
> + .name = "pse_algo",

Most power supply drivers use "-" instead of "_" in their names, so
probably it a good idea to continue doing so. I suggest to use
"pse-algorithm" as name.

> + .chrg_prof_type = PSY_CHRG_PROF_PSE,
> + .get_next_cc_cv = pse_get_next_cc_cv,
> + .get_batt_thresholds = pse_get_bat_thresholds,
> +};
> +static int __init pse_algo_init(void)
> +{
> + power_supply_register_charging_algo(&pse_algo);
> + return 0;
> +}
> +
> +module_init(pse_algo_init);
> diff --git a/include/linux/power/power_supply_charger.h b/include/linux/power/power_supply_charger.h
> index 2b59817..8f3797d 100644
> --- a/include/linux/power/power_supply_charger.h
> +++ b/include/linux/power/power_supply_charger.h
> @@ -94,8 +94,71 @@ enum battery_events {
>
> enum psy_batt_chrg_prof_type {
> PSY_CHRG_PROF_NONE = 0,
> + PSY_CHRG_PROF_PSE,
> };
>
> +/* Product Safety Engineering (PSE) compliant charging profile */
> +
> +/**
> + * struct psy_ps_temp_chg_table - charging temperature zones definition
> + * @temp_up_lim: upper temperature limit for each zone in Degree Celsius

Maybe simply use temp_max?

> + * @full_chrg_vol: charge voltage till battery full in mV
> + * @full_chrg_cur: charge current till battery full in mA
> + * @maint_chrg_vol_ll: voltage at which maintenance charging should start in mV
> + * @maint_chrg_vol_ul: voltage at which maintenance charging should stop in mV.

min and max instead of ll and ul improves readability IMHO.

> + * This is the charging voltage in maintenance charging mode
> + * @maint_chrg_cur: charge current in maintenance charging mode
> + *
> + * Charging temperature zone definition to decide the charging parameters on
> + * each zone. An array of the structure is used to define multiple temperature
> + * zones
> + */
> +
> +struct psy_ps_temp_chg_table {
> + short int temp_up_lim;
> + short int full_chrg_vol;
> + short int full_chrg_cur;
> + short int maint_chrg_vol_ll;
> + short int maint_chrg_vol_ul;
> + short int maint_chrg_cur;
> +} __packed;
> +
> +#define BATTID_STR_LEN 8
> +#define BATT_TEMP_NR_RNG 6
> +
> +/**
> + * struct psy_pse_chrg_prof - PSE charging profile structure
> + * @batt_id: battery identifier
> + * @battery_type: as defined in POWER_SUPPLY_TECHNOLOGY_*
> + * @capacity: battery capacity in mAh
> + * @voltage_max: maximum battery volatge in mV
> + * @chrg_term_ma: charge termination current in mA
> + * @low_batt_mv: Low battery level voltage in mV
> + * @disch_temp_ul: maximum operating temperature when battery is discharging
> + * @disch_temp_ll: lowest operating temperature when battery is discharging

min and max instead of ll and ul improves readability IMHO.

Please add in degree Celsius for temperatures.

> + * @temp_mon_ranges: number of temperature zones
> + * @psy_ps_temp_chg_table: temperature zone table array
> + * @temp_low_lim: minimum charging temperature

Please add in degree Celsius for temperatures. Also maybe simply use
temp_min.
> + * PSE compliant charging profile which can be stored in battery EEPROM
> + * (if digital battery interface like MIPI BIF/SDQ supported) or in secondary
> + * storage to support analog battery (with BSI sensing support)
> + */
> +
> +struct psy_pse_chrg_prof {
> + char batt_id[BATTID_STR_LEN];
> + u16 battery_type;
> + u16 capacity;
> + u16 voltage_max;
> + u16 chrg_term_mA;
> + u16 low_batt_mV;
> + s8 disch_temp_ul;
> + s8 disch_temp_ll;
> + u16 temp_mon_ranges;
> + struct psy_ps_temp_chg_table temp_mon_range[BATT_TEMP_NR_RNG];
> + s8 temp_low_lim;
> +} __packed;
> +
> /**
> * struct psy_batt_chrg_prof - power supply charging profile structure
> * @chrg_prof_type: charging profile type
> --
> 1.7.9.5
>
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