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Subject[PATCH v6 2/4] power: supply: Add support for the Qualcomm Battery Monitoring System
Date
This patch adds a driver for the BMS (Battery Monitoring System)
block of the PM8941 PMIC, it uses a lookup table defined in the
device tree to generate a capacity from the BMS supplied OCV, it
then amends the coulomb counter to that to increase the accuracy
of the estimated capacity.

Signed-off-by: Craig Tatlor <ctatlor97@gmail.com>
---

* Changes from v5:
Uses select for REGMAP_SPMI.

* Changes from v4:
Cleaned up percentage interpolation function,
uses new fixp interpolation helper,
added some more error cases,
uses devm_power_supply_register(),
uses a DIV_ROUND_CLOSEST for division and
uses micro(volts / amp hours) instead of
milli (volts / amp hours).

drivers/power/supply/Kconfig | 9 +
drivers/power/supply/Makefile | 1 +
drivers/power/supply/qcom_bms.c | 487 ++++++++++++++++++++++++++++++++
3 files changed, 497 insertions(+)
create mode 100644 drivers/power/supply/qcom_bms.c

diff --git a/drivers/power/supply/Kconfig b/drivers/power/supply/Kconfig
index 428b426842f4..75f2f375f992 100644
--- a/drivers/power/supply/Kconfig
+++ b/drivers/power/supply/Kconfig
@@ -82,6 +82,15 @@ config BATTERY_ACT8945A
Say Y here to enable support for power supply provided by
Active-semi ActivePath ACT8945A charger.

+config BATTERY_BMS
+ tristate "Qualcomm Battery Monitoring System driver"
+ depends on MFD_SPMI_PMIC || COMPILE_TEST
+ depends on OF
+ select REGMAP_SPMI
+ help
+ Say Y to include support for the Battery Monitoring hardware
+ found in some Qualcomm PM series PMICs.
+
config BATTERY_CPCAP
tristate "Motorola CPCAP PMIC battery driver"
depends on MFD_CPCAP && IIO
diff --git a/drivers/power/supply/Makefile b/drivers/power/supply/Makefile
index e83aa843bcc6..04204174b047 100644
--- a/drivers/power/supply/Makefile
+++ b/drivers/power/supply/Makefile
@@ -21,6 +21,7 @@ obj-$(CONFIG_BATTERY_88PM860X) += 88pm860x_battery.o
obj-$(CONFIG_BATTERY_ACT8945A) += act8945a_charger.o
obj-$(CONFIG_BATTERY_AXP20X) += axp20x_battery.o
obj-$(CONFIG_CHARGER_AXP20X) += axp20x_ac_power.o
+obj-$(CONFIG_BATTERY_BMS) += qcom_bms.o
obj-$(CONFIG_BATTERY_CPCAP) += cpcap-battery.o
obj-$(CONFIG_BATTERY_DS2760) += ds2760_battery.o
obj-$(CONFIG_BATTERY_DS2780) += ds2780_battery.o
diff --git a/drivers/power/supply/qcom_bms.c b/drivers/power/supply/qcom_bms.c
new file mode 100644
index 000000000000..e1d6fdbf11d1
--- /dev/null
+++ b/drivers/power/supply/qcom_bms.c
@@ -0,0 +1,487 @@
+// SPDX-License-Identifier: GPL
+
+/*
+ * Qualcomm Battery Monitoring System driver
+ *
+ * Copyright (C) 2018 Craig Tatlor <ctatlor97@gmail.com>
+ */
+
+#include <linux/module.h>
+#include <linux/fixp-arith.h>
+#include <linux/platform_device.h>
+#include <linux/power_supply.h>
+#include <linux/slab.h>
+#include <linux/bitops.h>
+#include <linux/of.h>
+#include <linux/of_platform.h>
+#include <linux/regmap.h>
+#include <linux/irq.h>
+#include <linux/interrupt.h>
+#include <linux/iio/consumer.h>
+
+#define REG_BMS_OCV_FOR_SOC_DATA0 0x90
+#define REG_BMS_SHDW_CC_DATA0 0xA8
+#define REG_BMS_CC_DATA_CTL 0x42
+#define REG_BMS_CC_CLEAR_CTL 0x4
+
+#define BMS_HOLD_OREG_DATA BIT(0)
+#define BMS_CLEAR_SHDW_CC BIT(6)
+
+#define BMS_CC_READING_RESOLUTION_N 542535
+#define BMS_CC_READING_RESOLUTION_D 10000
+#define BMS_CC_READING_TICKS 56
+#define BMS_SLEEP_CLK_HZ 32764
+
+#define SECONDS_PER_HOUR 3600
+#define TEMPERATURE_COLS 5
+#define MAX_CAPACITY_ROWS 50
+
+/* lookup table for ocv -> capacity conversion */
+struct bms_ocv_lut {
+ int rows;
+ s8 temp_legend[TEMPERATURE_COLS];
+ u8 capacity_legend[MAX_CAPACITY_ROWS];
+ u32 lut[MAX_CAPACITY_ROWS][TEMPERATURE_COLS];
+};
+
+/* lookup table for battery temperature -> fcc conversion */
+struct bms_fcc_lut {
+ s8 temp_legend[TEMPERATURE_COLS];
+ u32 lut[TEMPERATURE_COLS];
+};
+
+struct bms_device_info {
+ struct device *dev;
+ struct regmap *regmap;
+ struct bms_ocv_lut ocv_lut;
+ struct power_supply_desc bat_desc;
+ struct bms_fcc_lut fcc_lut;
+ struct iio_channel *adc;
+ struct mutex bms_output_lock;
+ u32 base_addr;
+
+ int ocv_thr_irq;
+ u32 ocv;
+};
+
+static bool between(int left, int right, int val)
+{
+ if (left <= val && val <= right)
+ return true;
+
+ if (left >= val && val >= right)
+ return true;
+
+ return false;
+}
+
+static int interpolate_capacity(int temp, u32 ocv,
+ struct bms_ocv_lut *ocv_lut)
+{
+ int pcj_minus_one = 0, pcj = 0, i2 = 0, i3 = 0, i, j;
+
+ for (j = 0; j < TEMPERATURE_COLS; j++)
+ if (temp <= ocv_lut->temp_legend[j])
+ break;
+
+ if (ocv >= ocv_lut->lut[0][j])
+ return ocv_lut->capacity_legend[0];
+
+ if (ocv <= ocv_lut->lut[ocv_lut->rows-1][j-1])
+ return ocv_lut->capacity_legend[ocv_lut->rows-1];
+
+ for (i = 0; i < ocv_lut->rows-1; i++) {
+ if (between(ocv_lut->lut[i][j],
+ ocv_lut->lut[i+1][j], ocv))
+ i2 = i;
+
+ if (between(ocv_lut->lut[i][j-1],
+ ocv_lut->lut[i+1][j-1], ocv))
+ i3 = i;
+ }
+
+ /* interpolate two capacities */
+ pcj = fixp_linear_interpolate(ocv_lut->lut[i2][j],
+ ocv_lut->capacity_legend[i2],
+ ocv_lut->lut[i2+1][j],
+ ocv_lut->capacity_legend[i2+1],
+ ocv);
+
+ pcj_minus_one = fixp_linear_interpolate(ocv_lut->lut[i3][j-1],
+ ocv_lut->capacity_legend[i3],
+ ocv_lut->lut[i3+1][j-1],
+ ocv_lut->capacity_legend[i3+1],
+ ocv);
+
+ /* interpolate them with the battery temperature */
+ return fixp_linear_interpolate(ocv_lut->temp_legend[j-1],
+ pcj_minus_one,
+ ocv_lut->temp_legend[j],
+ pcj,
+ temp);
+}
+
+static int interpolate_fcc(int temp, struct bms_fcc_lut *fcc_lut)
+{
+ int i;
+
+ for (i = 0; i < TEMPERATURE_COLS; i++)
+ if (temp <= fcc_lut->temp_legend[i])
+ break;
+
+ return fixp_linear_interpolate(fcc_lut->temp_legend[i-1],
+ fcc_lut->lut[i-1],
+ fcc_lut->temp_legend[i],
+ fcc_lut->lut[i],
+ temp);
+}
+
+static int bms_lock_output_data(struct bms_device_info *di)
+{
+ int ret;
+
+ ret = regmap_update_bits(di->regmap, di->base_addr +
+ REG_BMS_CC_DATA_CTL,
+ BMS_HOLD_OREG_DATA, BMS_HOLD_OREG_DATA);
+ if (ret) {
+ dev_err(di->dev, "failed to lock bms output: %d", ret);
+ return ret;
+ }
+
+ /*
+ * Sleep for at least 100 microseconds here to make sure
+ * there has been at least three cycles of the sleep clock
+ * so that the registers are correctly locked.
+ */
+ usleep_range(100, 1000);
+
+ return 0;
+}
+
+static int bms_unlock_output_data(struct bms_device_info *di)
+{
+ int ret;
+
+ ret = regmap_update_bits(di->regmap, di->base_addr +
+ REG_BMS_CC_DATA_CTL,
+ BMS_HOLD_OREG_DATA, 0);
+ if (ret) {
+ dev_err(di->dev, "failed to unlock bms output: %d", ret);
+ return ret;
+ }
+
+ return 0;
+}
+
+static int bms_read_ocv(struct bms_device_info *di, u32 *ocv)
+{
+ int ret;
+ u16 read_ocv;
+
+ mutex_lock(&di->bms_output_lock);
+
+ ret = bms_lock_output_data(di);
+ if (ret)
+ goto err_lock;
+
+ ret = regmap_bulk_read(di->regmap, di->base_addr+
+ REG_BMS_OCV_FOR_SOC_DATA0, &read_ocv, 2);
+ if (ret) {
+ dev_err(di->dev, "open circuit voltage read failed: %d", ret);
+ goto err_read;
+ }
+
+ dev_dbg(di->dev, "read open circuit voltage of: %d mv", read_ocv);
+
+
+ *ocv = read_ocv * 1000;
+
+err_read:
+ bms_unlock_output_data(di);
+
+err_lock:
+ mutex_unlock(&di->bms_output_lock);
+
+ return ret;
+}
+
+static int bms_read_cc(struct bms_device_info *di, s64 *cc_uah)
+{
+ int ret;
+ s64 cc_raw_s36, cc_raw, cc_uv, cc_pvh;
+
+ mutex_lock(&di->bms_output_lock);
+
+ ret = bms_lock_output_data(di);
+ if (ret)
+ goto err_lock;
+
+ ret = regmap_bulk_read(di->regmap, di->base_addr +
+ REG_BMS_SHDW_CC_DATA0,
+ &cc_raw_s36, 5);
+ if (ret) {
+ dev_err(di->dev, "coulomb counter read failed: %d", ret);
+ goto err_read;
+ }
+
+ ret = bms_unlock_output_data(di);
+ if (ret)
+ goto err_lock;
+
+ mutex_unlock(&di->bms_output_lock);
+
+ cc_raw = sign_extend32(cc_raw_s36, 28);
+
+ /* convert raw to uv */
+ cc_uv = div_s64(cc_raw * BMS_CC_READING_RESOLUTION_N,
+ BMS_CC_READING_RESOLUTION_D);
+
+ /* convert uv to pvh */
+ cc_pvh = div_s64(cc_uv * BMS_CC_READING_TICKS * 100000,
+ BMS_SLEEP_CLK_HZ * SECONDS_PER_HOUR);
+
+ /* divide by impedance */
+ *cc_uah = div_s64(cc_pvh, 10000);
+
+ dev_dbg(di->dev, "read coulomb counter value of: %lld uah", *cc_uah);
+
+ return 0;
+
+err_read:
+ bms_unlock_output_data(di);
+
+err_lock:
+ mutex_unlock(&di->bms_output_lock);
+
+ return ret;
+}
+
+static void bms_reset_cc(struct bms_device_info *di)
+{
+ int ret;
+
+ mutex_lock(&di->bms_output_lock);
+
+ ret = regmap_update_bits(di->regmap, di->base_addr +
+ REG_BMS_CC_CLEAR_CTL,
+ BMS_CLEAR_SHDW_CC,
+ BMS_CLEAR_SHDW_CC);
+ if (ret) {
+ dev_err(di->dev, "coulomb counter reset failed: %d", ret);
+ goto err_lock;
+ }
+
+ /* wait at least three sleep cycles for cc to reset */
+ usleep_range(100, 1000);
+
+ ret = regmap_update_bits(di->regmap, di->base_addr +
+ REG_BMS_CC_CLEAR_CTL,
+ BMS_CLEAR_SHDW_CC, 0);
+ if (ret)
+ dev_err(di->dev, "coulomb counter re-enable failed: %d", ret);
+
+err_lock:
+ mutex_unlock(&di->bms_output_lock);
+}
+
+static int bms_calculate_capacity(struct bms_device_info *di, int *capacity)
+{
+ unsigned long fcc;
+ int ret, temp, ocv_capacity, temp_degc;
+ s64 cc = 0;
+
+ ret = iio_read_channel_raw(di->adc, &temp);
+ if (ret < 0) {
+ dev_err(di->dev, "failed to read temperature: %d", ret);
+ return ret;
+ }
+
+ temp_degc = DIV_ROUND_CLOSEST(temp, 1000);
+
+ ret = bms_read_cc(di, &cc);
+ if (ret < 0) {
+ dev_err(di->dev, "failed to read coulomb counter: %d", ret);
+ return ret;
+ }
+
+ /* interpolate capacity from open circuit voltage */
+ ocv_capacity = interpolate_capacity(temp_degc, di->ocv,
+ &di->ocv_lut);
+
+ /* interpolate the full charge capacity from temperature */
+ fcc = interpolate_fcc(temp_degc, &di->fcc_lut);
+
+ /* append coloumb counter to capacity */
+ *capacity = DIV_ROUND_CLOSEST(fcc * ocv_capacity, 100);
+ *capacity = div_s64((*capacity - cc) * 100, fcc);
+
+ return 0;
+}
+
+
+
+/*
+ * Return power_supply property
+ */
+static int bms_get_property(struct power_supply *psy,
+ enum power_supply_property psp,
+ union power_supply_propval *val)
+{
+ struct bms_device_info *di = power_supply_get_drvdata(psy);
+ int ret;
+
+ switch (psp) {
+ case POWER_SUPPLY_PROP_CAPACITY:
+ ret = bms_calculate_capacity(di, &val->intval);
+ break;
+ default:
+ ret = -EINVAL;
+ break;
+ }
+
+ if (val->intval == INT_MAX || val->intval == INT_MIN)
+ ret = -EINVAL;
+
+ return ret;
+}
+
+static enum power_supply_property bms_props[] = {
+ POWER_SUPPLY_PROP_CAPACITY,
+};
+
+static irqreturn_t bms_ocv_thr_irq_handler(int irq, void *dev_id)
+{
+ struct bms_device_info *di = dev_id;
+
+ if (bms_read_ocv(di, &di->ocv) < 0)
+ return IRQ_HANDLED;
+
+ bms_reset_cc(di);
+ return IRQ_HANDLED;
+}
+
+static int bms_probe(struct platform_device *pdev)
+{
+ struct power_supply_config psy_cfg = {};
+ struct bms_device_info *di;
+ struct power_supply *bat;
+ int ret;
+
+ di = devm_kzalloc(&pdev->dev, sizeof(*di), GFP_KERNEL);
+ if (!di)
+ return -ENOMEM;
+
+ di->dev = &pdev->dev;
+
+ di->regmap = dev_get_regmap(pdev->dev.parent, NULL);
+ if (!di->regmap) {
+ dev_err(di->dev, "Unable to get regmap");
+ return -EINVAL;
+ }
+
+ di->adc = devm_iio_channel_get(&pdev->dev, "temp");
+ if (IS_ERR(di->adc))
+ return PTR_ERR(di->adc);
+
+ ret = of_property_read_u32(di->dev->of_node, "reg", &di->base_addr);
+ if (ret < 0)
+ return ret;
+
+ ret = of_property_read_u8_array(di->dev->of_node,
+ "qcom,ocv-temp-legend-celsius",
+ (u8 *)di->ocv_lut.temp_legend,
+ TEMPERATURE_COLS);
+ if (ret < 0) {
+ dev_err(di->dev, "no open circuit voltage temperature legend found");
+ return ret;
+ }
+
+ di->ocv_lut.rows = of_property_read_variable_u8_array(di->dev->of_node,
+ "qcom,ocv-capacity-legend",
+ di->ocv_lut.capacity_legend, 0,
+ MAX_CAPACITY_ROWS);
+ if (di->ocv_lut.rows < 0) {
+ dev_err(di->dev, "no open circuit voltage capacity legend found");
+ return ret;
+ }
+
+ ret = of_property_read_variable_u32_array(di->dev->of_node,
+ "qcom,ocv-lut-microvolt",
+ (u32 *)di->ocv_lut.lut,
+ TEMPERATURE_COLS,
+ TEMPERATURE_COLS *
+ MAX_CAPACITY_ROWS);
+ if (ret < 0) {
+ dev_err(di->dev, "no open circuit voltage lut array found");
+ return ret;
+ }
+
+ ret = of_property_read_u8_array(di->dev->of_node,
+ "qcom,fcc-temp-legend-celsius",
+ (u8 *)di->fcc_lut.temp_legend,
+ TEMPERATURE_COLS);
+ if (ret < 0) {
+ dev_err(di->dev, "no full charge capacity temperature legend found");
+ return ret;
+ }
+
+ ret = of_property_read_u32_array(di->dev->of_node,
+ "qcom,fcc-lut-microamp-hours",
+ di->fcc_lut.lut,
+ TEMPERATURE_COLS);
+ if (ret < 0) {
+ dev_err(di->dev, "no full charge capacity lut array found");
+ return ret;
+ }
+
+ ret = bms_read_ocv(di, &di->ocv);
+ if (ret < 0) {
+ dev_err(di->dev, "failed to read initial open circuit voltage: %d",
+ ret);
+ return ret;
+ }
+
+ mutex_init(&di->bms_output_lock);
+
+ di->ocv_thr_irq = platform_get_irq_byname(pdev, "ocv_thr");
+
+ ret = devm_request_threaded_irq(di->dev, di->ocv_thr_irq, NULL,
+ bms_ocv_thr_irq_handler,
+ IRQF_TRIGGER_RISING | IRQF_ONESHOT,
+ pdev->name, di);
+ if (ret < 0) {
+ dev_err(di->dev, "failed to request handler for open circuit voltage threshold IRQ");
+ return ret;
+ }
+
+
+ di->bat_desc.name = "bms";
+ di->bat_desc.type = POWER_SUPPLY_TYPE_BATTERY;
+ di->bat_desc.properties = bms_props;
+ di->bat_desc.num_properties = ARRAY_SIZE(bms_props);
+ di->bat_desc.get_property = bms_get_property;
+
+ psy_cfg.drv_data = di;
+ bat = devm_power_supply_register(di->dev, &di->bat_desc, &psy_cfg);
+
+ return PTR_ERR_OR_ZERO(bat);
+}
+
+static const struct of_device_id bms_of_match[] = {
+ {.compatible = "qcom,pm8941-bms", },
+ { },
+};
+MODULE_DEVICE_TABLE(of, bms_of_match);
+
+static struct platform_driver bms_driver = {
+ .probe = bms_probe,
+ .driver = {
+ .name = "qcom-bms",
+ .of_match_table = of_match_ptr(bms_of_match),
+ },
+};
+module_platform_driver(bms_driver);
+
+MODULE_AUTHOR("Craig Tatlor <ctatlor97@gmail.com>");
+MODULE_DESCRIPTION("Qualcomm BMS driver");
+MODULE_LICENSE("GPL");
--
2.17.0
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