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Commit dc1ad87c authored by Xiaozhe Shi's avatar Xiaozhe Shi
Browse files

power: qpnp-bms: fix batterydata reverse interpolation 



The BMS driver needs to look up open circuit voltages for a given
SoC. However, the current algorithm is a bit flawed. If the battery
profile is not monotonic, there is a risk of going to an infinite
loop.

Fix this by modifying the reverse lookup loop to be bounded, and to
modify the step size so that the OCV will converge instead of
oscillating.

Change-Id: I25ba92de9796c4b89b476a0eff39a542407205f0
Signed-off-by: default avatarXiaozhe Shi <xiaozhes@codeaurora.org>
parent ede485fc

drivers/power/qpnp-bms.c

+77 −43
Original line number Diff line number Diff line
@@ -1333,48 +1333,79 @@ static int calculate_unusable_charge_uah(struct qpnp_bms_chip *chip, 
	return uuc_uah_iavg;

}



static void find_ocv_for_soc(struct qpnp_bms_chip *chip,

				struct soc_params *params,

				int batt_temp,

				int shutdown_soc,

				int *ret_ocv_uv)

static s64 find_ocv_charge_for_soc(struct qpnp_bms_chip *chip,

				struct soc_params *params, int soc)

{

	s64 ocv_charge_uah;

	int pc, new_pc;

	int batt_temp_degc = batt_temp / 10;

	int ocv_uv;

	return div_s64((s64)soc * (params->fcc_uah - params->uuc_uah),

			100) + params->cc_uah + params->uuc_uah;

}



static int find_pc_for_soc(struct qpnp_bms_chip *chip,

			struct soc_params *params, int soc)

{

	int ocv_charge_uah = find_ocv_charge_for_soc(chip, params, soc);

	int pc;



	ocv_charge_uah = (s64)shutdown_soc

				* (params->fcc_uah - params->uuc_uah);

	ocv_charge_uah = div_s64(ocv_charge_uah, 100)

				+ params->cc_uah + params->uuc_uah;

	pc = DIV_ROUND_CLOSEST((int)ocv_charge_uah * 100, params->fcc_uah);

	pc = clamp(pc, 0, 100);

	pr_debug("soc = %d, fcc = %d uuc = %d rc = %d pc = %d\n",

			soc, params->fcc_uah, params->uuc_uah,

			ocv_charge_uah, pc);

	return pc;

}



	ocv_uv = interpolate_ocv(chip->pc_temp_ocv_lut, batt_temp_degc, pc);

#define SIGN(x) ((x) < 0 ? -1 : 1)

#define UV_PER_SPIN 50000

static int find_ocv_for_pc(struct qpnp_bms_chip *chip, int batt_temp, int pc)

{

	int new_pc;

	int batt_temp_degc = batt_temp / 10;

	int ocv_mv;

	int delta_mv = 5;

	int max_spin_count;

	int count = 0;

	int sign, new_sign;



	pr_debug("s_soc = %d, fcc = %d uuc = %d rc = %d, pc = %d, ocv mv = %d\n",

					shutdown_soc, params->fcc_uah,

					params->uuc_uah, (int)ocv_charge_uah,

					pc, ocv_uv);

	new_pc = interpolate_pc(chip->pc_temp_ocv_lut, batt_temp_degc, ocv_uv);

	pr_debug("test revlookup pc = %d for ocv = %d\n", new_pc, ocv_uv);

	ocv_mv = interpolate_ocv(chip->pc_temp_ocv_lut, batt_temp_degc, pc);



	while (abs(new_pc - pc) > 1) {

		int delta_mv = 5;

	new_pc = interpolate_pc(chip->pc_temp_ocv_lut, batt_temp_degc, ocv_mv);

	pr_debug("test revlookup pc = %d for ocv = %d\n", new_pc, ocv_mv);

	max_spin_count = 1 + (chip->max_voltage_uv - chip->v_cutoff_uv)

						/ UV_PER_SPIN;

	sign = SIGN(pc - new_pc);



		if (new_pc > pc)

			delta_mv = -1 * delta_mv;

	while (abs(new_pc - pc) != 0 && count < max_spin_count) {

		/*

		 * If the newly interpolated pc is larger than the lookup pc,

		 * the ocv should be reduced and vice versa

		 */

		new_sign = SIGN(pc - new_pc);

		/*

		 * If the sign has changed, then we have passed the lookup pc.

		 * reduce the ocv step size to get finer results.

		 *

		 * If we have already reduced the ocv step size and still

		 * passed the lookup pc, just stop and use the current ocv.

		 * This can only happen if the batterydata profile is

		 * non-monotonic anyways.

		 */

		if (new_sign != sign) {

			if (delta_mv > 1)

				delta_mv = 1;

			else

				break;

		}

		sign = new_sign;



		ocv_uv = ocv_uv + delta_mv;

		ocv_mv = ocv_mv + delta_mv * sign;

		new_pc = interpolate_pc(chip->pc_temp_ocv_lut,

				batt_temp_degc, ocv_uv);

				batt_temp_degc, ocv_mv);

		pr_debug("test revlookup pc = %d for ocv = %d\n",

				new_pc, ocv_uv);

			new_pc, ocv_mv);

		count++;

	}



	*ret_ocv_uv = ocv_uv * 1000;

	params->ocv_charge_uah = (int)ocv_charge_uah;

	return ocv_mv * 1000;

}



static int get_current_time(unsigned long *now_tm_sec)
@@ -1834,7 +1865,6 @@ static int charging_adjustments(struct qpnp_bms_chip *chip, 
				int vbat_uv, int ibat_ua, int batt_temp)

{

	int chg_soc, soc_ibat, batt_terminal_uv, weight_ibat, weight_cc;

	int new_ocv_uv;



	batt_terminal_uv = vbat_uv + (ibat_ua * chip->r_conn_mohm) / 1000;
@@ -1888,9 +1918,10 @@ static int charging_adjustments(struct qpnp_bms_chip *chip, 
	if (chg_soc > chip->prev_chg_soc) {

		chip->prev_chg_soc = chg_soc;



		find_ocv_for_soc(chip, params, batt_temp, chg_soc, &new_ocv_uv);

		chip->charging_adjusted_ocv = new_ocv_uv;

		pr_debug("CC CHG ADJ OCV = %d CHG SOC %d\n", new_ocv_uv,

		chip->charging_adjusted_ocv = find_ocv_for_pc(chip, batt_temp,

				find_pc_for_soc(chip, params, chg_soc));

		pr_debug("CC CHG ADJ OCV = %d CHG SOC %d\n",

				chip->charging_adjusted_ocv,

				chip->prev_chg_soc);

	}
@@ -2172,7 +2203,8 @@ static void configure_soc_wakeup(struct qpnp_bms_chip *chip, 
	cc_raw_64 = convert_cc_uah_to_raw(chip, target_cc_uah);

	cc_raw = convert_s64_to_s36(cc_raw_64);



	find_ocv_for_soc(chip, params, batt_temp, target_soc, &target_ocv_uv);

	target_ocv_uv = find_ocv_for_pc(chip, batt_temp,

				find_pc_for_soc(chip, params, target_soc));

	ocv_raw = convert_vbatt_uv_to_raw(chip, target_ocv_uv);



	/*
@@ -2202,8 +2234,7 @@ static int calculate_raw_soc(struct qpnp_bms_chip *chip, 
					struct soc_params *params,

					int batt_temp)

{

	int soc, new_ocv_uv;

	int remaining_usable_charge_uah;

	int soc, remaining_usable_charge_uah;



	/* calculate remaining usable charge */

	remaining_usable_charge_uah = params->ocv_charge_uah
@@ -2220,8 +2251,10 @@ static int calculate_raw_soc(struct qpnp_bms_chip *chip, 
		 * in a bad soc. Adjust ocv to get 0 soc

		 */

		pr_debug("soc is %d, adjusting pon ocv to make it 0\n", soc);

		find_ocv_for_soc(chip, params, batt_temp, 0, &new_ocv_uv);

		chip->last_ocv_uv = new_ocv_uv;

		chip->last_ocv_uv = find_ocv_for_pc(chip, batt_temp,

				find_pc_for_soc(chip, params, 0));

		params->ocv_charge_uah = find_ocv_charge_for_soc(chip,

				params, 0);



		remaining_usable_charge_uah = params->ocv_charge_uah

					- params->cc_uah
@@ -2259,7 +2292,7 @@ static int calculate_state_of_charge(struct qpnp_bms_chip *chip, 
{

	struct soc_params params;

	int soc, previous_soc, shutdown_soc, new_calculated_soc;

	int remaining_usable_charge_uah, new_ocv_uv;

	int remaining_usable_charge_uah;



	calculate_soc_params(chip, raw, &params, batt_temp);

	if (!is_battery_present(chip)) {
@@ -2290,9 +2323,10 @@ static int calculate_state_of_charge(struct qpnp_bms_chip *chip, 
		 */

		pr_debug("soc = %d before forcing shutdown_soc = %d\n",

							soc, shutdown_soc);

		find_ocv_for_soc(chip, &params, batt_temp,

					shutdown_soc, &new_ocv_uv);

		chip->last_ocv_uv = new_ocv_uv;

		chip->last_ocv_uv = find_ocv_for_pc(chip, batt_temp,

				find_pc_for_soc(chip, &params, shutdown_soc));

		params.ocv_charge_uah = find_ocv_charge_for_soc(chip,

				&params, shutdown_soc);



		remaining_usable_charge_uah = params.ocv_charge_uah

					- params.cc_uah