power: pm8921-charger: implement ir compensation
The charger hardware has a +/-30mv error for vdd_max settings. This
means that when vdd_max is set to 4200mV the actual voltage on vph_pwr
line could range from 4170mV to 4230mV. This further means that when
constant current to constant voltage transition happens, the battery
may not be charged up to 4200mV - leading to an premature end of charge.
Fix this by implementing periodic IR compensation. On a device measure the
resistance from the vbat terminal to the ground by shorting the +ve and
-ve of the battery terminals (without a battery), this will be referred to
as rconn in the description. In the code it is rconn_mohm to reflect the
units.
The voltage at battery terminal will be
Vbat(terminal) = Vbat(xoadc) + Ibat * rconn
where Ibat is the current flowing out of (or into if -ve) of the battery.
Vbat(xoadc) and Ibat can be obtained by using the override mode of the
bms. So Vbat(terminal) can be deduced and compensated by increasing
vdd_max. This also helps in increasing constant current mode thereby
decreasing constant voltage mode and decreasing the overall charging time.
The value of rconn will be specific to a PCB layout, it is
passed in from platform_data.
Change-Id: If8df93333ca6b0bad35505895a4fc5577562fadd
Signed-off-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>
diff --git a/arch/arm/mach-msm/board-8960-pmic.c b/arch/arm/mach-msm/board-8960-pmic.c
index 4e18f89..3b84875 100644
--- a/arch/arm/mach-msm/board-8960-pmic.c
+++ b/arch/arm/mach-msm/board-8960-pmic.c
@@ -432,6 +432,7 @@
.warm_bat_voltage = 4100,
.thermal_mitigation = pm8921_therm_mitigation,
.thermal_levels = ARRAY_SIZE(pm8921_therm_mitigation),
+ .rconn_mohm = 18,
};
static struct pm8xxx_misc_platform_data pm8xxx_misc_pdata = {
diff --git a/drivers/power/pm8921-charger.c b/drivers/power/pm8921-charger.c
index 78757f9..4f73a7e 100644
--- a/drivers/power/pm8921-charger.c
+++ b/drivers/power/pm8921-charger.c
@@ -262,6 +262,7 @@
struct wake_lock eoc_wake_lock;
enum pm8921_chg_cold_thr cold_thr;
enum pm8921_chg_hot_thr hot_thr;
+ int rconn_mohm;
};
static int usb_max_current;
@@ -2389,6 +2390,80 @@
round_jiffies_relative(msecs_to_jiffies
(chip->update_time)));
}
+#define VDD_LOOP_ACTIVE_BIT BIT(3)
+#define VDD_MAX_INCREASE_MV 400
+static int vdd_max_increase_mv = VDD_MAX_INCREASE_MV;
+module_param(vdd_max_increase_mv, int, 0644);
+
+static int ichg_threshold_ua = -400000;
+module_param(ichg_threshold_ua, int, 0644);
+static void adjust_vdd_max_for_fastchg(struct pm8921_chg_chip *chip)
+{
+ int ichg_meas_ua, vbat_uv;
+ int ichg_meas_ma;
+ int adj_vdd_max_mv, programmed_vdd_max;
+ int vbat_batt_terminal_uv;
+ int vbat_batt_terminal_mv;
+ int reg_loop;
+ int delta_mv = 0;
+
+ if (chip->rconn_mohm == 0) {
+ pr_debug("Exiting as rconn_mohm is 0\n");
+ return;
+ }
+ /* adjust vdd_max only in normal temperature zone */
+ if (chip->is_bat_cool || chip->is_bat_warm) {
+ pr_debug("Exiting is_bat_cool = %d is_batt_warm = %d\n",
+ chip->is_bat_cool, chip->is_bat_warm);
+ return;
+ }
+
+ reg_loop = pm_chg_get_regulation_loop(chip);
+ if (!(reg_loop & VDD_LOOP_ACTIVE_BIT)) {
+ pr_debug("Exiting Vdd loop is not active reg loop=0x%x\n",
+ reg_loop);
+ return;
+ }
+
+ pm8921_bms_get_simultaneous_battery_voltage_and_current(&ichg_meas_ua,
+ &vbat_uv);
+ if (ichg_meas_ua >= 0) {
+ pr_debug("Exiting ichg_meas_ua = %d > 0\n", ichg_meas_ua);
+ return;
+ }
+ if (ichg_meas_ua <= ichg_threshold_ua) {
+ pr_debug("Exiting ichg_meas_ua = %d < ichg_threshold_ua = %d\n",
+ ichg_meas_ua, ichg_threshold_ua);
+ return;
+ }
+ ichg_meas_ma = ichg_meas_ua / 1000;
+
+ /* rconn_mohm is in milliOhms */
+ vbat_batt_terminal_uv = vbat_uv + ichg_meas_ma * the_chip->rconn_mohm;
+ vbat_batt_terminal_mv = vbat_batt_terminal_uv/1000;
+ pm_chg_vddmax_get(the_chip, &programmed_vdd_max);
+
+ delta_mv = chip->max_voltage_mv - vbat_batt_terminal_mv;
+
+ adj_vdd_max_mv = programmed_vdd_max + delta_mv;
+ pr_debug("vdd_max needs to be changed by %d mv from %d to %d\n",
+ delta_mv,
+ programmed_vdd_max,
+ adj_vdd_max_mv);
+
+ if (adj_vdd_max_mv < chip->max_voltage_mv) {
+ pr_debug("adj vdd_max lower than default max voltage\n");
+ return;
+ }
+
+ if (adj_vdd_max_mv > (chip->max_voltage_mv + vdd_max_increase_mv))
+ adj_vdd_max_mv = chip->max_voltage_mv + vdd_max_increase_mv;
+
+ pr_debug("adjusting vdd_max_mv to %d to make "
+ "vbat_batt_termial_uv = %d to %d\n",
+ adj_vdd_max_mv, vbat_batt_terminal_uv, chip->max_voltage_mv);
+ pm_chg_vddmax_set(chip, adj_vdd_max_mv);
+}
enum {
CHG_IN_PROGRESS,
@@ -2442,8 +2517,6 @@
}
pr_debug("vddmax = %d vbat_meas_mv=%d\n",
vbat_programmed, vbat_meas_mv);
- if (vbat_meas_mv < vbat_programmed - VBAT_TOLERANCE_MV)
- return CHG_IN_PROGRESS;
if (last_vbat_programmed == -EINVAL)
last_vbat_programmed = vbat_programmed;
@@ -2455,10 +2528,6 @@
return CHG_IN_PROGRESS;
}
- /*
- * TODO if charging from an external charger
- * check SOC instead of regulation loop
- */
regulation_loop = pm_chg_get_regulation_loop(chip);
if (regulation_loop < 0) {
pr_err("couldnt read the regulation loop err=%d\n",
@@ -2518,10 +2587,9 @@
end = is_charging_finished(chip);
if (end == CHG_NOT_IN_PROGRESS) {
- /* enable fastchg irq */
- count = 0;
- wake_unlock(&chip->eoc_wake_lock);
- return;
+ count = 0;
+ wake_unlock(&chip->eoc_wake_lock);
+ return;
}
if (end == CHG_FINISHED) {
@@ -2547,6 +2615,7 @@
chgdone_irq_handler(chip->pmic_chg_irq[CHGDONE_IRQ], chip);
wake_unlock(&chip->eoc_wake_lock);
} else {
+ adjust_vdd_max_for_fastchg(chip);
pr_debug("EOC count = %d\n", count);
schedule_delayed_work(&chip->eoc_work,
round_jiffies_relative(msecs_to_jiffies
@@ -2687,6 +2756,23 @@
module_param_call(disabled, set_disable_status_param, param_get_uint,
&charging_disabled, 0644);
+static int rconn_mohm;
+static int set_rconn_mohm(const char *val, struct kernel_param *kp)
+{
+ int ret;
+ struct pm8921_chg_chip *chip = the_chip;
+
+ ret = param_set_int(val, kp);
+ if (ret) {
+ pr_err("error setting value %d\n", ret);
+ return ret;
+ }
+ if (chip)
+ chip->rconn_mohm = rconn_mohm;
+ return 0;
+}
+module_param_call(rconn_mohm, set_rconn_mohm, param_get_uint,
+ &rconn_mohm, 0644);
/**
* set_thermal_mitigation_level -
*
@@ -3004,6 +3090,7 @@
static int __devinit pm8921_chg_hw_init(struct pm8921_chg_chip *chip)
{
int rc;
+ int vdd_safe;
rc = pm_chg_masked_write(chip, SYS_CONFIG_2,
BOOT_DONE_BIT, BOOT_DONE_BIT);
@@ -3012,7 +3099,13 @@
return rc;
}
- rc = pm_chg_vddsafe_set(chip, chip->max_voltage_mv);
+ vdd_safe = chip->max_voltage_mv + VDD_MAX_INCREASE_MV;
+
+ if (vdd_safe > PM8921_CHG_VDDSAFE_MAX)
+ vdd_safe = PM8921_CHG_VDDSAFE_MAX;
+
+ rc = pm_chg_vddsafe_set(chip, vdd_safe);
+
if (rc) {
pr_err("Failed to set safe voltage to %d rc=%d\n",
chip->max_voltage_mv, rc);
@@ -3505,6 +3598,7 @@
chip->cold_thr = pdata->cold_thr;
chip->hot_thr = pdata->hot_thr;
+ chip->rconn_mohm = pdata->rconn_mohm;
rc = pm8921_chg_hw_init(chip);
if (rc) {
diff --git a/include/linux/mfd/pm8xxx/pm8921-charger.h b/include/linux/mfd/pm8xxx/pm8921-charger.h
index 31af535..8a3b999 100644
--- a/include/linux/mfd/pm8xxx/pm8921-charger.h
+++ b/include/linux/mfd/pm8xxx/pm8921-charger.h
@@ -100,6 +100,10 @@
* VBAT_THERM goes below 35% of VREF_THERM, if low the
* battery will be considered hot when VBAT_THERM goes
* below 25% of VREF_THERM. Hardware defaults to low.
+ * @rconn_mohm: resistance in milliOhm from the vbat sense to ground
+ * with the battery terminals shorted. This indicates
+ * resistance of the pads, connectors, battery terminals
+ * and rsense.
*/
struct pm8921_charger_platform_data {
struct pm8xxx_charger_core_data charger_cdata;
@@ -131,6 +135,7 @@
int thermal_levels;
enum pm8921_chg_cold_thr cold_thr;
enum pm8921_chg_hot_thr hot_thr;
+ int rconn_mohm;
};
enum pm8921_charger_source {