[PATCH v3 1/2] dt-bindings: power: supply: ltc3350-charger: Add bindings

[PATCH v3 1/2] dt-bindings: power: supply: ltc3350-charger: Add bindings

[Mike Looijmans]

The LTC3350 is a backup power controller that can charge and monitor
a series stack of one to four supercapacitors.

Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

---

Changes in v3:
Fix $id after rename to lltc,ltc3350.yaml

Changes in v2:
Rename to lltc,ltc3350.yaml
Fix spaces and indentation

 .../bindings/power/supply/lltc,ltc3350.yaml   | 54 +++++++++++++++++++
 1 file changed, 54 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/power/supply/lltc,ltc3350.yaml

diff --git a/Documentation/devicetree/bindings/power/supply/lltc,ltc3350.yaml b/Documentation/devicetree/bindings/power/supply/lltc,ltc3350.yaml
new file mode 100644
index 000000000000..dca7fe0f0d8f
--- /dev/null
+++ b/Documentation/devicetree/bindings/power/supply/lltc,ltc3350.yaml
@@ -0,0 +1,54 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+# Copyright (C) 2024 Topic Embedded Products
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/power/supply/lltc,ltc3350.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Linear Technology (Analog Devices) LTC3350 Supercap Charger
+
+maintainers:
+  - Mike Looijmans <mike.looijmans@topic.nl>
+
+description: |
+  The LTC3350 is a High Current Supercapacitor Backup Controller and System
+  Monitor.
+  Specifications about the charger can be found at:
+    https://www.analog.com/en/products/ltc3350.html
+
+properties:
+  compatible:
+    enum:
+      - lltc,ltc3350
+
+  reg:
+    maxItems: 1
+
+  lltc,rsnsc-micro-ohms:
+    description: Capacitor charger sense resistor in microohm.
+    minimum: 1000
+
+  lltc,rsnsi-micro-ohms:
+    description: Input current sense resistor in microohm.
+    minimum: 1000
+
+required:
+  - compatible
+  - reg
+  - lltc,rsnsc-micro-ohms
+  - lltc,rsnsi-micro-ohms
+
+additionalProperties: false
+
+examples:
+  - |
+    i2c {
+      #address-cells = <1>;
+      #size-cells = <0>;
+      charger: battery-charger@9 {
+        compatible = "lltc,ltc3350";
+        reg = <0x9>;
+        lltc,rsnsc-micro-ohms = <10000>;
+        lltc,rsnsi-micro-ohms = <10000>;
+      };
+    };
-- 
2.34.1


Met vriendelijke groet / kind regards,

Mike Looijmans
System Expert


TOPIC Embedded Products B.V.
Materiaalweg 4, 5681 RJ Best
The Netherlands

T: +31 (0) 499 33 69 69
E: mike.looijmans@topic.nl
W: www.topic.nl

Please consider the environment before printing this e-mail

[PATCH v3 2/2] power: supply: ltc3350-charger: Add driver

[Mike Looijmans]

The LTC3350 is a backup power controller that can charge and monitor
a series stack of one to four supercapacitors.

Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>

---

(no changes since v2)

Changes in v2:
Duplicate "vin_ov" and "vin_uv" attributes

 drivers/power/supply/Kconfig           |  10 +
 drivers/power/supply/Makefile          |   1 +
 drivers/power/supply/ltc3350-charger.c | 718 +++++++++++++++++++++++++
 3 files changed, 729 insertions(+)
 create mode 100644 drivers/power/supply/ltc3350-charger.c

diff --git a/drivers/power/supply/Kconfig b/drivers/power/supply/Kconfig
index 3e31375491d5..7cb1a66e522d 100644
--- a/drivers/power/supply/Kconfig
+++ b/drivers/power/supply/Kconfig
@@ -514,6 +514,16 @@ config CHARGER_LT3651
 	  Say Y to include support for the Analog Devices (Linear Technology)
 	  LT3651 battery charger which reports its status via GPIO lines.
 
+config CHARGER_LTC3350
+	tristate "LTC3350 Supercapacitor Backup Controller and System Monitor"
+	depends on I2C
+	select REGMAP_I2C
+	select I2C_SMBUS
+	help
+	  Say Y to include support for the Analog Devices (Linear Technology)
+	  LTC3350 Supercapacitor Backup Controller and System Monitor connected
+	  to I2C.
+
 config CHARGER_LTC4162L
 	tristate "LTC4162-L charger"
 	depends on I2C
diff --git a/drivers/power/supply/Makefile b/drivers/power/supply/Makefile
index 58b567278034..a8d618e4ac91 100644
--- a/drivers/power/supply/Makefile
+++ b/drivers/power/supply/Makefile
@@ -72,6 +72,7 @@ obj-$(CONFIG_CHARGER_LP8788)	+= lp8788-charger.o
 obj-$(CONFIG_CHARGER_GPIO)	+= gpio-charger.o
 obj-$(CONFIG_CHARGER_MANAGER)	+= charger-manager.o
 obj-$(CONFIG_CHARGER_LT3651)	+= lt3651-charger.o
+obj-$(CONFIG_CHARGER_LTC3350)	+= ltc3350-charger.o
 obj-$(CONFIG_CHARGER_LTC4162L)	+= ltc4162-l-charger.o
 obj-$(CONFIG_CHARGER_MAX14577)	+= max14577_charger.o
 obj-$(CONFIG_CHARGER_DETECTOR_MAX14656)	+= max14656_charger_detector.o
diff --git a/drivers/power/supply/ltc3350-charger.c b/drivers/power/supply/ltc3350-charger.c
new file mode 100644
index 000000000000..84c7a3ca914e
--- /dev/null
+++ b/drivers/power/supply/ltc3350-charger.c
@@ -0,0 +1,718 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Driver for Analog Devices (Linear Technology) LTC3350
+ * High Current Supercapacitor Backup Controller and System Monitor
+ * Copyright (C) 2024, Topic Embedded Products
+ */
+
+#include <linux/module.h>
+#include <linux/delay.h>
+#include <linux/of_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/power_supply.h>
+#include <linux/i2c.h>
+#include <linux/regmap.h>
+
+/* Registers (names based on what datasheet uses) */
+#define LTC3350_REG_CLR_ALARMS		0x00
+#define LTC3350_REG_MSK_ALARMS		0x01
+#define LTC3350_REG_MSK_MON_STATUS	0x02
+#define LTC3350_REG_CAP_ESR_PER		0x04
+#define LTC3350_REG_VCAPFB_DAC		0x05
+#define LTC3350_REG_VSHUNT		0x06
+#define LTC3350_REG_CAP_UV_LVL		0x07
+#define LTC3350_REG_CAP_OV_LVL		0x08
+#define LTC3350_REG_GPI_UV_LVL		0x09
+#define LTC3350_REG_GPI_OV_LVL		0x0A
+#define LTC3350_REG_VIN_UV_LVL		0x0B
+#define LTC3350_REG_VIN_OV_LVL		0x0C
+#define LTC3350_REG_VCAP_UV_LVL		0x0D
+#define LTC3350_REG_VCAP_OV_LVL		0x0E
+#define LTC3350_REG_VOUT_UV_LVL		0x0F
+#define LTC3350_REG_VOUT_OV_LVL		0x10
+#define LTC3350_REG_IIN_OC_LVL		0x11
+#define LTC3350_REG_ICHG_UC_LVL		0x12
+#define LTC3350_REG_DTEMP_COLD_LVL	0x13
+#define LTC3350_REG_DTEMP_HOT_LVL	0x14
+#define LTC3350_REG_ESR_HI_LVL		0x15
+#define LTC3350_REG_CAP_LO_LVL		0x16
+#define LTC3350_REG_CTL_REG		0x17
+#define LTC3350_REG_NUM_CAPS		0x1A
+#define LTC3350_REG_CHRG_STATUS		0x1B
+#define LTC3350_REG_MON_STATUS		0x1C
+#define LTC3350_REG_ALARM_REG		0x1D
+#define LTC3350_REG_MEAS_CAP		0x1E
+#define LTC3350_REG_MEAS_ESR		0x1F
+#define LTC3350_REG_MEAS_VCAP1		0x20
+#define LTC3350_REG_MEAS_VCAP2		0x21
+#define LTC3350_REG_MEAS_VCAP3		0x22
+#define LTC3350_REG_MEAS_VCAP4		0x23
+#define LTC3350_REG_MEAS_GPI		0x24
+#define LTC3350_REG_MEAS_VIN		0x25
+#define LTC3350_REG_MEAS_VCAP		0x26
+#define LTC3350_REG_MEAS_VOUT		0x27
+#define LTC3350_REG_MEAS_IIN		0x28
+#define LTC3350_REG_MEAS_ICHG		0x29
+#define LTC3350_REG_MEAS_DTEMP		0x2A
+
+/* LTC3350_REG_CLR_ALARMS, LTC3350_REG_MASK_ALARMS, LTC3350_REG_ALARM_REG */
+#define LTC3350_MSK_CAP_UV	BIT(0)	/* capacitor undervoltage alarm */
+#define LTC3350_MSK_CAP_OV	BIT(1)	/* capacitor overvoltage alarm */
+#define LTC3350_MSK_GPI_UV	BIT(2)	/* GPI undervoltage alarm */
+#define LTC3350_MSK_GPI_OV	BIT(3)	/* GPI overvoltage alarm */
+#define LTC3350_MSK_VIN_UV	BIT(4)	/* VIN undervoltage alarm */
+#define LTC3350_MSK_VIN_OV	BIT(5)	/* VIN overvoltage alarm */
+#define LTC3350_MSK_VCAP_UV	BIT(6)	/* VCAP undervoltage alarm */
+#define LTC3350_MSK_VCAP_OV	BIT(7)	/* VCAP overvoltage alarm */
+#define LTC3350_MSK_VOUT_UV	BIT(8)	/* VOUT undervoltage alarm */
+#define LTC3350_MSK_VOUT_OV	BIT(9)	/* VOUT overvoltage alarm */
+#define LTC3350_MSK_IIN_OC	BIT(10)	/* input overcurrent alarm */
+#define LTC3350_MSK_ICHG_UC	BIT(11)	/* charge undercurrent alarm */
+#define LTC3350_MSK_DTEMP_COLD	BIT(12)	/* die temperature cold alarm */
+#define LTC3350_MSK_DTEMP_HOT	BIT(13)	/* die temperature hot alarm */
+#define LTC3350_MSK_ESR_HI	BIT(14)	/* ESR high alarm */
+#define LTC3350_MSK_CAP_LO	BIT(15)	/* capacitance low alarm */
+
+/* LTC3350_REG_MSK_MON_STATUS masks */
+#define LTC3350_MSK_MON_CAPESR_ACTIVE		BIT(0)
+#define LTC3350_MSK_MON_CAPESR_SCHEDULED	BIT(1)
+#define LTC3350_MSK_MON_CAPESR_PENDING		BIT(2)
+#define LTC3350_MSK_MON_CAP_DONE		BIT(3)
+#define LTC3350_MSK_MON_ESR_DONE		BIT(4)
+#define LTC3350_MSK_MON_CAP_FAILED		BIT(5)
+#define LTC3350_MSK_MON_ESR_FAILED		BIT(6)
+#define LTC3350_MSK_MON_POWER_FAILED		BIT(8)
+#define LTC3350_MSK_MON_POWER_RETURNED		BIT(9)
+
+/* LTC3350_REG_CTL_REG */
+/* Begin a capacitance and ESR measurement when possible */
+#define LTC3350_CTL_STRT_CAPESR		BIT(0)
+/* A one in this bit location enables the input buffer on the GPI pin */
+#define LTC3350_CTL_GPI_BUFFER_EN	BIT(1)
+/* Stops an active capacitance/ESR measurement */
+#define LTC3350_CTL_STOP_CAPESR		BIT(2)
+/* Increases capacitor measurement resolution by 100x for smaller capacitors */
+#define LTC3350_CTL_CAP_SCALE		BIT(3)
+
+/* LTC3350_REG_CHRG_STATUS */
+#define LTC3350_CHRG_STEPDOWN	BIT(0)	/* Synchronous controller in step-down mode (charging) */
+#define LTC3350_CHRG_STEPUP	BIT(1)	/* Synchronous controller in step-up mode (backup) */
+#define LTC3350_CHRG_CV		BIT(2)	/* The charger is in constant voltage mode */
+#define LTC3350_CHRG_UVLO	BIT(3)	/* The charger is in undervoltage lockout */
+#define LTC3350_CHRG_INPUT_ILIM	BIT(4)	/* The charger is in input current limit */
+#define LTC3350_CHRG_CAPPG	BIT(5)	/* The capacitor voltage is above power good threshold */
+#define LTC3350_CHRG_SHNT	BIT(6)	/* The capacitor manager is shunting */
+#define LTC3350_CHRG_BAL	BIT(7)	/* The capacitor manager is balancing */
+#define LTC3350_CHRG_DIS	BIT(8)	/* Charger disabled for capacitance measurement */
+#define LTC3350_CHRG_CI		BIT(9)	/* The charger is in constant current mode */
+#define LTC3350_CHRG_PFO	BIT(11)	/* Input voltage is below PFI threshold */
+
+/* LTC3350_REG_MON_STATUS */
+#define LTC3350_MON_CAPESR_ACTIVE	BIT(0)	/* Capacitance/ESR measurement in progress */
+#define LTC3350_MON_CAPESR_SCHEDULED	BIT(1)	/* Waiting programmed time */
+#define LTC3350_MON_CAPESR_PENDING	BIT(2)	/* Waiting for satisfactory conditions */
+#define LTC3350_MON_CAP_DONE		BIT(3)	/* Capacitance measurement has completed */
+#define LTC3350_MON_ESR_DONE		BIT(4)	/* ESR Measurement has completed */
+#define LTC3350_MON_CAP_FAILED		BIT(5)	/* Last capacitance measurement failed */
+#define LTC3350_MON_ESR_FAILED		BIT(6)	/* Last ESR measurement failed */
+#define LTC3350_MON_POWER_FAILED	BIT(8)	/* Unable to charge */
+#define LTC3350_MON_POWER_RETURNED	BIT(9)	/* Able to charge */
+
+
+struct ltc3350_info {
+	struct i2c_client	*client;
+	struct regmap		*regmap;
+	struct power_supply	*charger;
+	u32 rsnsc;	/* Series resistor that sets charge current, microOhm */
+	u32 rsnsi;	/* Series resistor to measure input current, microOhm */
+};
+
+/*
+ * About LTC3350 "alarm" functions: Setting a bit in the LTC3350_REG_MSK_ALARMS
+ * register enables the alarm. The alarm will trigger an SMBALERT only once.
+ * To reset the alarm, write a "1" bit to LTC3350_REG_CLR_ALARMS. Then the alarm
+ * will trigger another SMBALERT when conditions are met (may be immediately).
+ * After writing to one of the corresponding level registers, enable the alarm,
+ * so that a UEVENT triggers when the alarm goes off.
+ */
+static void ltc3350_enable_alarm(struct ltc3350_info *info, unsigned int reg)
+{
+	unsigned int mask;
+
+	/* Register locations correspond to alarm mask bits */
+	mask = BIT(reg - LTC3350_REG_CAP_UV_LVL);
+	/* Clear the alarm bit so it may trigger again */
+	regmap_write(info->regmap, LTC3350_REG_CLR_ALARMS, mask);
+	/* Enable the alarm */
+	regmap_update_bits(info->regmap, LTC3350_REG_MSK_ALARMS, mask, mask);
+}
+
+/* Convert enum value to POWER_SUPPLY_STATUS value */
+static int ltc3350_state_decode(unsigned int value)
+{
+	if (value & LTC3350_CHRG_STEPUP)
+		return POWER_SUPPLY_STATUS_DISCHARGING; /* running on backup */
+
+	if (value & LTC3350_CHRG_PFO)
+		return POWER_SUPPLY_STATUS_NOT_CHARGING;
+
+	if (value & LTC3350_CHRG_STEPDOWN) {
+		/* The chip remains in CV mode indefinitely, hence "full" */
+		if (value & LTC3350_CHRG_CV)
+			return POWER_SUPPLY_STATUS_FULL;
+
+		return POWER_SUPPLY_STATUS_CHARGING;
+	}
+
+	/* Not in step down? Must be full then (never seen this) */
+	return POWER_SUPPLY_STATUS_FULL;
+};
+
+static int ltc3350_get_status(struct ltc3350_info *info, union power_supply_propval *val)
+{
+	unsigned int regval;
+	int ret;
+
+	ret = regmap_read(info->regmap, LTC3350_REG_CHRG_STATUS, &regval);
+	if (ret)
+		return ret;
+
+	val->intval = ltc3350_state_decode(regval);
+
+	return 0;
+}
+
+static int ltc3350_charge_status_decode(unsigned int value)
+{
+	if (!(value & LTC3350_CHRG_STEPDOWN))
+		return POWER_SUPPLY_CHARGE_TYPE_NONE;
+
+	/* constant voltage is "topping off" */
+	if (value & LTC3350_CHRG_CV)
+		return POWER_SUPPLY_CHARGE_TYPE_TRICKLE;
+
+	/* input limiter */
+	if (value & LTC3350_CHRG_INPUT_ILIM)
+		return POWER_SUPPLY_CHARGE_TYPE_ADAPTIVE;
+
+	/* constant current is "fast" */
+	if (value & LTC3350_CHRG_CI)
+		return POWER_SUPPLY_CHARGE_TYPE_FAST;
+
+	return POWER_SUPPLY_CHARGE_TYPE_UNKNOWN;
+}
+
+static int ltc3350_get_charge_type(struct ltc3350_info *info, union power_supply_propval *val)
+{
+	unsigned int regval;
+	int ret;
+
+	ret = regmap_read(info->regmap, LTC3350_REG_CHRG_STATUS, &regval);
+	if (ret)
+		return ret;
+
+	val->intval = ltc3350_charge_status_decode(regval);
+
+	return 0;
+}
+
+static int ltc3350_get_online(struct ltc3350_info *info, union power_supply_propval *val)
+{
+	unsigned int regval;
+	int ret;
+
+	ret = regmap_read(info->regmap, LTC3350_REG_MON_STATUS, &regval);
+	if (ret)
+		return ret;
+
+	/* indicates if input voltage is sufficient to charge */
+	val->intval = !!(regval & LTC3350_MON_POWER_RETURNED);
+
+	return 0;
+}
+
+static int ltc3350_get_input_voltage(struct ltc3350_info *info, union power_supply_propval *val)
+{
+	unsigned int regval;
+	int ret;
+
+	ret = regmap_read(info->regmap, LTC3350_REG_MEAS_VIN, &regval);
+	if (ret)
+		return ret;
+
+	/* 2.21mV/LSB */
+	val->intval =  regval * 2210;
+
+	return 0;
+}
+
+static int ltc3350_get_input_current(struct ltc3350_info *info, union power_supply_propval *val)
+{
+	unsigned int regval;
+	int ret;
+
+	ret = regmap_read(info->regmap, LTC3350_REG_MEAS_IIN, &regval);
+	if (ret)
+		return ret;
+
+	/* 1.983µV/RSNSI amperes per LSB */
+	ret = regval * 19830;
+	ret /= info->rsnsi;
+	ret *= 100;
+
+	val->intval = ret;
+
+	return 0;
+}
+
+static int ltc3350_get_icharge(struct ltc3350_info *info, union power_supply_propval *val)
+{
+	unsigned int regval;
+	int ret;
+
+	ret = regmap_read(info->regmap, LTC3350_REG_MEAS_ICHG, &regval);
+	if (ret)
+		return ret;
+
+	/* 1.983µV/RSNSC amperes per LSB */
+	ret = regval * 19830;
+	ret /= info->rsnsc;
+	ret *= 100;
+
+	val->intval = ret;
+
+	return 0;
+}
+
+static int ltc3350_get_icharge_max(struct ltc3350_info *info, union power_supply_propval *val)
+{
+	/* I_CHG(MAX) = 32mV / RSNSC (Ampere) */
+	val->intval = 3200000000U / (info->rsnsc / 10);
+
+	return 0;
+}
+
+static int ltc3350_get_iin_max(struct ltc3350_info *info, union power_supply_propval *val)
+{
+	/* I_IN(MAX) = 32mV / RSNSI (Ampere) */
+	val->intval = 3200000000U / (info->rsnsi / 10);
+
+	return 0;
+}
+
+
+static int ltc3350_get_die_temp(struct ltc3350_info *info, unsigned int reg,
+				union power_supply_propval *val)
+{
+	unsigned int regval;
+	int ret;
+
+	ret = regmap_read(info->regmap, reg, &regval);
+	if (ret)
+		return ret;
+
+	/* 0.028°C per LSB – 251.4°C */
+	ret = 280 * regval;
+	ret /= 100; /* Centidegrees scale */
+	ret -= 25140;
+	val->intval = ret;
+
+	return 0;
+}
+
+static int ltc3350_set_die_temp(struct ltc3350_info *info, unsigned int reg, int val)
+{
+	unsigned int regval;
+	int ret;
+
+	/* 0.028°C per LSB – 251.4°C */
+	regval = val + 25140;
+	regval *= 100;
+	regval /= 280;
+
+	ret = regmap_write(info->regmap, reg, regval);
+	if (ret)
+		return ret;
+
+	ltc3350_enable_alarm(info, reg);
+	return 0;
+}
+
+/* Custom properties */
+
+static ssize_t ltc3350_attr_show(struct device *dev,
+				 struct device_attribute *attr, char *buf,
+				 unsigned int reg, unsigned int scale)
+{
+	struct power_supply *psy = to_power_supply(dev);
+	struct ltc3350_info *info = power_supply_get_drvdata(psy);
+	unsigned int regval;
+	int ret;
+
+	ret = regmap_read(info->regmap, reg, &regval);
+	if (ret)
+		return ret;
+
+	regval *= scale; /* Scale is in 10 μV units */
+	regval /= 10;
+
+	return sprintf(buf, "%u\n", regval);
+}
+
+static ssize_t ltc3350_attr_store(struct device *dev, struct device_attribute *attr,
+				  const char *buf, size_t count,
+				  unsigned int reg, unsigned int scale)
+{
+	struct power_supply *psy = to_power_supply(dev);
+	struct ltc3350_info *info = power_supply_get_drvdata(psy);
+	unsigned long val;
+	int ret;
+
+	ret = kstrtoul(buf, 10, &val);
+	if (ret)
+		return ret;
+
+	val *= 10;
+	val = DIV_ROUND_CLOSEST(val, scale); /* Scale is in 10 μV units */
+
+	ret = regmap_write(info->regmap, reg, val);
+	if (ret)
+		return ret;
+
+	/* When writing to one of the LVL registers, update the alarm mask */
+	if (reg >= LTC3350_REG_CAP_UV_LVL && reg <= LTC3350_REG_CAP_LO_LVL)
+		ltc3350_enable_alarm(info, reg);
+
+	return count;
+}
+
+#define LTC3350_DEVICE_ATTR_RO(_name, _reg, _scale)				\
+static ssize_t _name##_show(struct device *dev, struct device_attribute *attr,	\
+			    char *buf)						\
+{										\
+	return ltc3350_attr_show(dev, attr, buf, _reg, _scale);			\
+}										\
+static DEVICE_ATTR_RO(_name)
+
+#define LTC3350_DEVICE_ATTR_RW(_name, _reg, _scale)				\
+static ssize_t _name##_show(struct device *dev, struct device_attribute *attr,	\
+			    char *buf)						\
+{										\
+	return ltc3350_attr_show(dev, attr, buf, _reg, _scale);			\
+}										\
+static ssize_t _name##_store(struct device *dev, struct device_attribute *attr, \
+			     const char *buf, size_t count)			\
+{										\
+	return ltc3350_attr_store(dev, attr, buf, count, _reg, _scale);		\
+}										\
+static DEVICE_ATTR_RW(_name)
+
+/* Shunt voltage, 183.5μV per LSB */
+LTC3350_DEVICE_ATTR_RW(vshunt, LTC3350_REG_VSHUNT, 1835);
+
+/* Single capacitor voltages, 183.5μV per LSB */
+LTC3350_DEVICE_ATTR_RO(vcap1, LTC3350_REG_MEAS_VCAP1, 1835);
+LTC3350_DEVICE_ATTR_RO(vcap2, LTC3350_REG_MEAS_VCAP2, 1835);
+LTC3350_DEVICE_ATTR_RO(vcap3, LTC3350_REG_MEAS_VCAP3, 1835);
+LTC3350_DEVICE_ATTR_RO(vcap4, LTC3350_REG_MEAS_VCAP4, 1835);
+LTC3350_DEVICE_ATTR_RW(cap_uv, LTC3350_REG_CAP_UV_LVL, 1835);
+LTC3350_DEVICE_ATTR_RW(cap_ov, LTC3350_REG_CAP_OV_LVL, 1835);
+
+/* General purpose input, 183.5μV per LSB */
+LTC3350_DEVICE_ATTR_RO(gpi, LTC3350_REG_MEAS_GPI, 1835);
+LTC3350_DEVICE_ATTR_RW(gpi_uv, LTC3350_REG_GPI_UV_LVL, 1835);
+LTC3350_DEVICE_ATTR_RW(gpi_ov, LTC3350_REG_GPI_OV_LVL, 1835);
+
+/* Input voltage, 2.21mV per LSB */
+LTC3350_DEVICE_ATTR_RO(vin, LTC3350_REG_MEAS_VIN, 22100);
+LTC3350_DEVICE_ATTR_RW(vin_uv, LTC3350_REG_VIN_UV_LVL, 22100);
+LTC3350_DEVICE_ATTR_RW(vin_ov, LTC3350_REG_VIN_OV_LVL, 22100);
+
+/* Capacitor stack voltage, 1.476 mV per LSB */
+LTC3350_DEVICE_ATTR_RO(vcap, LTC3350_REG_MEAS_VCAP, 14760);
+LTC3350_DEVICE_ATTR_RW(vcap_uv, LTC3350_REG_VCAP_UV_LVL, 14760);
+LTC3350_DEVICE_ATTR_RW(vcap_ov, LTC3350_REG_VCAP_OV_LVL, 14760);
+
+/* Output, 2.21mV per LSB */
+LTC3350_DEVICE_ATTR_RO(vout, LTC3350_REG_MEAS_VOUT, 22100);
+LTC3350_DEVICE_ATTR_RW(vout_uv, LTC3350_REG_VOUT_UV_LVL, 22100);
+LTC3350_DEVICE_ATTR_RW(vout_ov, LTC3350_REG_VOUT_OV_LVL, 22100);
+
+static ssize_t num_caps_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct power_supply *psy = to_power_supply(dev);
+	struct ltc3350_info *info = power_supply_get_drvdata(psy);
+	unsigned int regval;
+	int ret;
+
+	ret = regmap_read(info->regmap, LTC3350_REG_NUM_CAPS, &regval);
+	if (ret)
+		return ret;
+
+	return sprintf(buf, "%u\n", regval + 1);
+}
+static DEVICE_ATTR_RO(num_caps);
+
+static ssize_t charge_status_show(struct device *dev, struct device_attribute *attr, char *buf)
+{
+	struct power_supply *psy = to_power_supply(dev);
+	struct ltc3350_info *info = power_supply_get_drvdata(psy);
+	unsigned int regval;
+	int ret;
+
+	ret = regmap_read(info->regmap, LTC3350_REG_CHRG_STATUS, &regval);
+	if (ret)
+		return ret;
+
+	return sprintf(buf, "0x%x\n", regval);
+}
+static DEVICE_ATTR_RO(charge_status);
+
+static struct attribute *ltc3350_sysfs_entries[] = {
+	&dev_attr_vshunt.attr,
+	&dev_attr_vcap1.attr,
+	&dev_attr_vcap2.attr,
+	&dev_attr_vcap3.attr,
+	&dev_attr_vcap4.attr,
+	&dev_attr_cap_uv.attr,
+	&dev_attr_cap_ov.attr,
+	&dev_attr_gpi.attr,
+	&dev_attr_gpi_uv.attr,
+	&dev_attr_gpi_ov.attr,
+	&dev_attr_vin.attr,
+	&dev_attr_vin_uv.attr,
+	&dev_attr_vin_ov.attr,
+	&dev_attr_vcap.attr,
+	&dev_attr_vcap_uv.attr,
+	&dev_attr_vcap_ov.attr,
+	&dev_attr_vout.attr,
+	&dev_attr_vout_uv.attr,
+	&dev_attr_vout_ov.attr,
+	&dev_attr_num_caps.attr,
+	&dev_attr_charge_status.attr,
+	NULL,
+};
+
+static const struct attribute_group ltc3350_attr_group = {
+	.name	= NULL,	/* put in device directory */
+	.attrs	= ltc3350_sysfs_entries,
+};
+
+static const struct attribute_group *ltc3350_attr_groups[] = {
+	&ltc3350_attr_group,
+	NULL,
+};
+
+static int ltc3350_get_property(struct power_supply *psy, enum power_supply_property psp,
+				union power_supply_propval *val)
+{
+	struct ltc3350_info *info = power_supply_get_drvdata(psy);
+
+	switch (psp) {
+	case POWER_SUPPLY_PROP_STATUS:
+		return ltc3350_get_status(info, val);
+	case POWER_SUPPLY_PROP_CHARGE_TYPE:
+		return ltc3350_get_charge_type(info, val);
+	case POWER_SUPPLY_PROP_ONLINE:
+		return ltc3350_get_online(info, val);
+	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
+		return ltc3350_get_input_voltage(info, val);
+	case POWER_SUPPLY_PROP_CURRENT_NOW:
+		return ltc3350_get_input_current(info, val);
+	case POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT:
+		return ltc3350_get_icharge(info, val);
+	case POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT_MAX:
+		return ltc3350_get_icharge_max(info, val);
+	case POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT:
+		return ltc3350_get_iin_max(info, val);
+	case POWER_SUPPLY_PROP_TEMP:
+		return ltc3350_get_die_temp(info, LTC3350_REG_MEAS_DTEMP, val);
+	case POWER_SUPPLY_PROP_TEMP_ALERT_MIN:
+		return ltc3350_get_die_temp(info, LTC3350_REG_DTEMP_COLD_LVL, val);
+	case POWER_SUPPLY_PROP_TEMP_ALERT_MAX:
+		return ltc3350_get_die_temp(info, LTC3350_REG_DTEMP_HOT_LVL, val);
+	default:
+		return -EINVAL;
+	}
+}
+
+static int ltc3350_set_property(struct power_supply *psy, enum power_supply_property psp,
+				const union power_supply_propval *val)
+{
+	struct ltc3350_info *info = power_supply_get_drvdata(psy);
+
+	switch (psp) {
+	case POWER_SUPPLY_PROP_TEMP_ALERT_MIN:
+		return ltc3350_set_die_temp(info, LTC3350_REG_DTEMP_COLD_LVL, val->intval);
+	case POWER_SUPPLY_PROP_TEMP_ALERT_MAX:
+		return ltc3350_set_die_temp(info, LTC3350_REG_DTEMP_HOT_LVL, val->intval);
+	default:
+		return -EINVAL;
+	}
+}
+
+static int ltc3350_property_is_writeable(struct power_supply *psy, enum power_supply_property psp)
+{
+	switch (psp) {
+	case POWER_SUPPLY_PROP_TEMP_ALERT_MIN:
+	case POWER_SUPPLY_PROP_TEMP_ALERT_MAX:
+		return 1;
+	default:
+		return 0;
+	}
+}
+
+/* Charger power supply property routines */
+static enum power_supply_property ltc3350_properties[] = {
+	POWER_SUPPLY_PROP_STATUS,
+	POWER_SUPPLY_PROP_CHARGE_TYPE,
+	POWER_SUPPLY_PROP_ONLINE,
+	POWER_SUPPLY_PROP_VOLTAGE_NOW,
+	POWER_SUPPLY_PROP_CURRENT_NOW,
+	POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT,
+	POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT_MAX,
+	POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT,
+	POWER_SUPPLY_PROP_TEMP,
+	POWER_SUPPLY_PROP_TEMP_ALERT_MIN,
+	POWER_SUPPLY_PROP_TEMP_ALERT_MAX,
+};
+
+static const struct power_supply_desc ltc3350_desc = {
+	.name		= "ltc3350",
+	.type		= POWER_SUPPLY_TYPE_MAINS,
+	.properties	= ltc3350_properties,
+	.num_properties	= ARRAY_SIZE(ltc3350_properties),
+	.get_property	= ltc3350_get_property,
+	.set_property	= ltc3350_set_property,
+	.property_is_writeable = ltc3350_property_is_writeable,
+};
+
+static bool ltc3350_is_writeable_reg(struct device *dev, unsigned int reg)
+{
+	/* all registers up to this one are writeable */
+	return reg < LTC3350_REG_NUM_CAPS;
+}
+
+static bool ltc3350_is_volatile_reg(struct device *dev, unsigned int reg)
+{
+	/* read-only status registers and self-clearing register */
+	return reg > LTC3350_REG_NUM_CAPS || reg == LTC3350_REG_CLR_ALARMS;
+}
+
+static const struct regmap_config ltc3350_regmap_config = {
+	.reg_bits	= 8,
+	.val_bits	= 16,
+	.val_format_endian = REGMAP_ENDIAN_LITTLE,
+	.writeable_reg	= ltc3350_is_writeable_reg,
+	.volatile_reg	= ltc3350_is_volatile_reg,
+	.max_register	= LTC3350_REG_MEAS_DTEMP,
+	.cache_type	= REGCACHE_MAPLE,
+};
+
+static int ltc3350_probe(struct i2c_client *client)
+{
+	struct i2c_adapter *adapter = client->adapter;
+	struct device *dev = &client->dev;
+	struct ltc3350_info *info;
+	struct power_supply_config ltc3350_config = {};
+	int ret;
+
+	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WORD_DATA)) {
+		dev_err(dev, "No support for SMBUS_WORD_DATA\n");
+		return -ENODEV;
+	}
+	info = devm_kzalloc(dev, sizeof(*info), GFP_KERNEL);
+	if (!info)
+		return -ENOMEM;
+
+	info->client = client;
+	i2c_set_clientdata(client, info);
+
+	info->regmap = devm_regmap_init_i2c(client, &ltc3350_regmap_config);
+	if (IS_ERR(info->regmap)) {
+		dev_err(dev, "Failed to initialize register map\n");
+		return PTR_ERR(info->regmap);
+	}
+
+	ret = device_property_read_u32(dev, "lltc,rsnsc-micro-ohms",
+				       &info->rsnsc);
+	if (ret) {
+		dev_err(dev, "Missing lltc,rsnsc-micro-ohms property\n");
+		return ret;
+	}
+	if (!info->rsnsc)
+		return -EINVAL;
+
+	ret = device_property_read_u32(dev, "lltc,rsnsi-micro-ohms",
+				       &info->rsnsi);
+	if (ret) {
+		dev_err(dev, "Missing lltc,rsnsi-micro-ohms property\n");
+		return ret;
+	}
+	if (!info->rsnsi)
+		return -EINVAL;
+
+	/* Clear and disable all interrupt sources*/
+	ret = regmap_write(info->regmap, LTC3350_REG_CLR_ALARMS, 0xFFFF);
+	if (ret) {
+		dev_err(dev, "Failed to write configuration\n");
+		return ret;
+	}
+	regmap_write(info->regmap, LTC3350_REG_MSK_ALARMS, 0);
+	regmap_write(info->regmap, LTC3350_REG_MSK_MON_STATUS, 0);
+
+	ltc3350_config.of_node = dev->of_node;
+	ltc3350_config.drv_data = info;
+	ltc3350_config.attr_grp = ltc3350_attr_groups;
+
+	info->charger = devm_power_supply_register(dev, &ltc3350_desc,
+						   &ltc3350_config);
+	if (IS_ERR(info->charger)) {
+		dev_err(dev, "Failed to register charger\n");
+		return PTR_ERR(info->charger);
+	}
+
+	/* Enable interrupts on status changes */
+	regmap_write(info->regmap, LTC3350_REG_MSK_MON_STATUS,
+		     LTC3350_MON_POWER_FAILED | LTC3350_MON_POWER_RETURNED);
+
+	return 0;
+}
+
+static void ltc3350_alert(struct i2c_client *client, enum i2c_alert_protocol type,
+			  unsigned int flag)
+{
+	struct ltc3350_info *info = i2c_get_clientdata(client);
+
+	if (type != I2C_PROTOCOL_SMBUS_ALERT)
+		return;
+
+	power_supply_changed(info->charger);
+}
+
+static const struct i2c_device_id ltc3350_i2c_id_table[] = {
+	{ "ltc3350", 0 },
+	{ },
+};
+MODULE_DEVICE_TABLE(i2c, ltc3350_i2c_id_table);
+
+static const struct of_device_id ltc3350_of_match[] = {
+	{ .compatible = "lltc,ltc3350", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, ltc3350_of_match);
+
+static struct i2c_driver ltc3350_driver = {
+	.probe		= ltc3350_probe,
+	.alert		= ltc3350_alert,
+	.id_table	= ltc3350_i2c_id_table,
+	.driver = {
+		.name		= "ltc3350-charger",
+		.of_match_table	= of_match_ptr(ltc3350_of_match),
+	},
+};
+module_i2c_driver(ltc3350_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Mike Looijmans <mike.looijmans@topic.nl>");
+MODULE_DESCRIPTION("LTC3350 charger driver");
-- 
2.34.1


Met vriendelijke groet / kind regards,

Mike Looijmans
System Expert


TOPIC Embedded Products B.V.
Materiaalweg 4, 5681 RJ Best
The Netherlands

T: +31 (0) 499 33 69 69
E: mike.looijmans@topic.nl
W: www.topic.nl

Please consider the environment before printing this e-mail

Re: [PATCH v3 2/2] power: supply: ltc3350-charger: Add driver

[Sebastian Reichel]

[-- Attachment #1: Type: text/plain, Size: 29479 bytes --]

Hi,

On Tue, Apr 09, 2024 at 03:54:41PM +0200, Mike Looijmans wrote:
> The LTC3350 is a backup power controller that can charge and monitor
> a series stack of one to four supercapacitors.
> 
> Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
> 
> ---

please share output of
./tools/testing/selftests/power_supply/test_power_supply_properties.sh
below the fold with your next submission. It's useful for verifying,
that you got the unit scaling correct for the standard properties :)

> (no changes since v2)
> 
> Changes in v2:
> Duplicate "vin_ov" and "vin_uv" attributes
> 
>  drivers/power/supply/Kconfig           |  10 +
>  drivers/power/supply/Makefile          |   1 +
>  drivers/power/supply/ltc3350-charger.c | 718 +++++++++++++++++++++++++
>  3 files changed, 729 insertions(+)
>  create mode 100644 drivers/power/supply/ltc3350-charger.c
> 
> diff --git a/drivers/power/supply/Kconfig b/drivers/power/supply/Kconfig
> index 3e31375491d5..7cb1a66e522d 100644
> --- a/drivers/power/supply/Kconfig
> +++ b/drivers/power/supply/Kconfig
> @@ -514,6 +514,16 @@ config CHARGER_LT3651
>  	  Say Y to include support for the Analog Devices (Linear Technology)
>  	  LT3651 battery charger which reports its status via GPIO lines.
>  
> +config CHARGER_LTC3350
> +	tristate "LTC3350 Supercapacitor Backup Controller and System Monitor"
> +	depends on I2C
> +	select REGMAP_I2C
> +	select I2C_SMBUS
> +	help
> +	  Say Y to include support for the Analog Devices (Linear Technology)
> +	  LTC3350 Supercapacitor Backup Controller and System Monitor connected
> +	  to I2C.
> +
>  config CHARGER_LTC4162L
>  	tristate "LTC4162-L charger"
>  	depends on I2C
> diff --git a/drivers/power/supply/Makefile b/drivers/power/supply/Makefile
> index 58b567278034..a8d618e4ac91 100644
> --- a/drivers/power/supply/Makefile
> +++ b/drivers/power/supply/Makefile
> @@ -72,6 +72,7 @@ obj-$(CONFIG_CHARGER_LP8788)	+= lp8788-charger.o
>  obj-$(CONFIG_CHARGER_GPIO)	+= gpio-charger.o
>  obj-$(CONFIG_CHARGER_MANAGER)	+= charger-manager.o
>  obj-$(CONFIG_CHARGER_LT3651)	+= lt3651-charger.o
> +obj-$(CONFIG_CHARGER_LTC3350)	+= ltc3350-charger.o
>  obj-$(CONFIG_CHARGER_LTC4162L)	+= ltc4162-l-charger.o
>  obj-$(CONFIG_CHARGER_MAX14577)	+= max14577_charger.o
>  obj-$(CONFIG_CHARGER_DETECTOR_MAX14656)	+= max14656_charger_detector.o
> diff --git a/drivers/power/supply/ltc3350-charger.c b/drivers/power/supply/ltc3350-charger.c
> new file mode 100644
> index 000000000000..84c7a3ca914e
> --- /dev/null
> +++ b/drivers/power/supply/ltc3350-charger.c
> @@ -0,0 +1,718 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Driver for Analog Devices (Linear Technology) LTC3350
> + * High Current Supercapacitor Backup Controller and System Monitor
> + * Copyright (C) 2024, Topic Embedded Products
> + */
> +
> +#include <linux/module.h>
> +#include <linux/delay.h>
> +#include <linux/of_device.h>

replace of_device.h with mod_devicetable.h (which defines of_device_id).

> +#include <linux/pm_runtime.h>
> +#include <linux/power_supply.h>

add

#include <linux/property.h>

since you are using device_property_*

> +#include <linux/i2c.h>
> +#include <linux/regmap.h>
> +
> +/* Registers (names based on what datasheet uses) */
> +#define LTC3350_REG_CLR_ALARMS		0x00
> +#define LTC3350_REG_MSK_ALARMS		0x01
> +#define LTC3350_REG_MSK_MON_STATUS	0x02
> +#define LTC3350_REG_CAP_ESR_PER		0x04
> +#define LTC3350_REG_VCAPFB_DAC		0x05
> +#define LTC3350_REG_VSHUNT		0x06
> +#define LTC3350_REG_CAP_UV_LVL		0x07
> +#define LTC3350_REG_CAP_OV_LVL		0x08
> +#define LTC3350_REG_GPI_UV_LVL		0x09
> +#define LTC3350_REG_GPI_OV_LVL		0x0A
> +#define LTC3350_REG_VIN_UV_LVL		0x0B
> +#define LTC3350_REG_VIN_OV_LVL		0x0C
> +#define LTC3350_REG_VCAP_UV_LVL		0x0D
> +#define LTC3350_REG_VCAP_OV_LVL		0x0E
> +#define LTC3350_REG_VOUT_UV_LVL		0x0F
> +#define LTC3350_REG_VOUT_OV_LVL		0x10
> +#define LTC3350_REG_IIN_OC_LVL		0x11
> +#define LTC3350_REG_ICHG_UC_LVL		0x12
> +#define LTC3350_REG_DTEMP_COLD_LVL	0x13
> +#define LTC3350_REG_DTEMP_HOT_LVL	0x14
> +#define LTC3350_REG_ESR_HI_LVL		0x15
> +#define LTC3350_REG_CAP_LO_LVL		0x16
> +#define LTC3350_REG_CTL_REG		0x17
> +#define LTC3350_REG_NUM_CAPS		0x1A
> +#define LTC3350_REG_CHRG_STATUS		0x1B
> +#define LTC3350_REG_MON_STATUS		0x1C
> +#define LTC3350_REG_ALARM_REG		0x1D
> +#define LTC3350_REG_MEAS_CAP		0x1E
> +#define LTC3350_REG_MEAS_ESR		0x1F
> +#define LTC3350_REG_MEAS_VCAP1		0x20
> +#define LTC3350_REG_MEAS_VCAP2		0x21
> +#define LTC3350_REG_MEAS_VCAP3		0x22
> +#define LTC3350_REG_MEAS_VCAP4		0x23
> +#define LTC3350_REG_MEAS_GPI		0x24
> +#define LTC3350_REG_MEAS_VIN		0x25
> +#define LTC3350_REG_MEAS_VCAP		0x26
> +#define LTC3350_REG_MEAS_VOUT		0x27
> +#define LTC3350_REG_MEAS_IIN		0x28
> +#define LTC3350_REG_MEAS_ICHG		0x29
> +#define LTC3350_REG_MEAS_DTEMP		0x2A
> +
> +/* LTC3350_REG_CLR_ALARMS, LTC3350_REG_MASK_ALARMS, LTC3350_REG_ALARM_REG */
> +#define LTC3350_MSK_CAP_UV	BIT(0)	/* capacitor undervoltage alarm */
> +#define LTC3350_MSK_CAP_OV	BIT(1)	/* capacitor overvoltage alarm */
> +#define LTC3350_MSK_GPI_UV	BIT(2)	/* GPI undervoltage alarm */
> +#define LTC3350_MSK_GPI_OV	BIT(3)	/* GPI overvoltage alarm */
> +#define LTC3350_MSK_VIN_UV	BIT(4)	/* VIN undervoltage alarm */
> +#define LTC3350_MSK_VIN_OV	BIT(5)	/* VIN overvoltage alarm */
> +#define LTC3350_MSK_VCAP_UV	BIT(6)	/* VCAP undervoltage alarm */
> +#define LTC3350_MSK_VCAP_OV	BIT(7)	/* VCAP overvoltage alarm */
> +#define LTC3350_MSK_VOUT_UV	BIT(8)	/* VOUT undervoltage alarm */
> +#define LTC3350_MSK_VOUT_OV	BIT(9)	/* VOUT overvoltage alarm */
> +#define LTC3350_MSK_IIN_OC	BIT(10)	/* input overcurrent alarm */
> +#define LTC3350_MSK_ICHG_UC	BIT(11)	/* charge undercurrent alarm */
> +#define LTC3350_MSK_DTEMP_COLD	BIT(12)	/* die temperature cold alarm */
> +#define LTC3350_MSK_DTEMP_HOT	BIT(13)	/* die temperature hot alarm */
> +#define LTC3350_MSK_ESR_HI	BIT(14)	/* ESR high alarm */
> +#define LTC3350_MSK_CAP_LO	BIT(15)	/* capacitance low alarm */
> +
> +/* LTC3350_REG_MSK_MON_STATUS masks */
> +#define LTC3350_MSK_MON_CAPESR_ACTIVE		BIT(0)
> +#define LTC3350_MSK_MON_CAPESR_SCHEDULED	BIT(1)
> +#define LTC3350_MSK_MON_CAPESR_PENDING		BIT(2)
> +#define LTC3350_MSK_MON_CAP_DONE		BIT(3)
> +#define LTC3350_MSK_MON_ESR_DONE		BIT(4)
> +#define LTC3350_MSK_MON_CAP_FAILED		BIT(5)
> +#define LTC3350_MSK_MON_ESR_FAILED		BIT(6)
> +#define LTC3350_MSK_MON_POWER_FAILED		BIT(8)
> +#define LTC3350_MSK_MON_POWER_RETURNED		BIT(9)
> +
> +/* LTC3350_REG_CTL_REG */
> +/* Begin a capacitance and ESR measurement when possible */
> +#define LTC3350_CTL_STRT_CAPESR		BIT(0)
> +/* A one in this bit location enables the input buffer on the GPI pin */
> +#define LTC3350_CTL_GPI_BUFFER_EN	BIT(1)
> +/* Stops an active capacitance/ESR measurement */
> +#define LTC3350_CTL_STOP_CAPESR		BIT(2)
> +/* Increases capacitor measurement resolution by 100x for smaller capacitors */
> +#define LTC3350_CTL_CAP_SCALE		BIT(3)
> +
> +/* LTC3350_REG_CHRG_STATUS */
> +#define LTC3350_CHRG_STEPDOWN	BIT(0)	/* Synchronous controller in step-down mode (charging) */
> +#define LTC3350_CHRG_STEPUP	BIT(1)	/* Synchronous controller in step-up mode (backup) */
> +#define LTC3350_CHRG_CV		BIT(2)	/* The charger is in constant voltage mode */
> +#define LTC3350_CHRG_UVLO	BIT(3)	/* The charger is in undervoltage lockout */
> +#define LTC3350_CHRG_INPUT_ILIM	BIT(4)	/* The charger is in input current limit */
> +#define LTC3350_CHRG_CAPPG	BIT(5)	/* The capacitor voltage is above power good threshold */
> +#define LTC3350_CHRG_SHNT	BIT(6)	/* The capacitor manager is shunting */
> +#define LTC3350_CHRG_BAL	BIT(7)	/* The capacitor manager is balancing */
> +#define LTC3350_CHRG_DIS	BIT(8)	/* Charger disabled for capacitance measurement */
> +#define LTC3350_CHRG_CI		BIT(9)	/* The charger is in constant current mode */
> +#define LTC3350_CHRG_PFO	BIT(11)	/* Input voltage is below PFI threshold */
> +
> +/* LTC3350_REG_MON_STATUS */
> +#define LTC3350_MON_CAPESR_ACTIVE	BIT(0)	/* Capacitance/ESR measurement in progress */
> +#define LTC3350_MON_CAPESR_SCHEDULED	BIT(1)	/* Waiting programmed time */
> +#define LTC3350_MON_CAPESR_PENDING	BIT(2)	/* Waiting for satisfactory conditions */
> +#define LTC3350_MON_CAP_DONE		BIT(3)	/* Capacitance measurement has completed */
> +#define LTC3350_MON_ESR_DONE		BIT(4)	/* ESR Measurement has completed */
> +#define LTC3350_MON_CAP_FAILED		BIT(5)	/* Last capacitance measurement failed */
> +#define LTC3350_MON_ESR_FAILED		BIT(6)	/* Last ESR measurement failed */
> +#define LTC3350_MON_POWER_FAILED	BIT(8)	/* Unable to charge */
> +#define LTC3350_MON_POWER_RETURNED	BIT(9)	/* Able to charge */
> +
> +
> +struct ltc3350_info {
> +	struct i2c_client	*client;
> +	struct regmap		*regmap;
> +	struct power_supply	*charger;
> +	u32 rsnsc;	/* Series resistor that sets charge current, microOhm */
> +	u32 rsnsi;	/* Series resistor to measure input current, microOhm */
> +};
> +
> +/*
> + * About LTC3350 "alarm" functions: Setting a bit in the LTC3350_REG_MSK_ALARMS
> + * register enables the alarm. The alarm will trigger an SMBALERT only once.
> + * To reset the alarm, write a "1" bit to LTC3350_REG_CLR_ALARMS. Then the alarm
> + * will trigger another SMBALERT when conditions are met (may be immediately).
> + * After writing to one of the corresponding level registers, enable the alarm,
> + * so that a UEVENT triggers when the alarm goes off.
> + */
> +static void ltc3350_enable_alarm(struct ltc3350_info *info, unsigned int reg)
> +{
> +	unsigned int mask;
> +
> +	/* Register locations correspond to alarm mask bits */
> +	mask = BIT(reg - LTC3350_REG_CAP_UV_LVL);
> +	/* Clear the alarm bit so it may trigger again */
> +	regmap_write(info->regmap, LTC3350_REG_CLR_ALARMS, mask);
> +	/* Enable the alarm */
> +	regmap_update_bits(info->regmap, LTC3350_REG_MSK_ALARMS, mask, mask);
> +}
> +
> +/* Convert enum value to POWER_SUPPLY_STATUS value */
> +static int ltc3350_state_decode(unsigned int value)
> +{
> +	if (value & LTC3350_CHRG_STEPUP)
> +		return POWER_SUPPLY_STATUS_DISCHARGING; /* running on backup */
> +
> +	if (value & LTC3350_CHRG_PFO)
> +		return POWER_SUPPLY_STATUS_NOT_CHARGING;
> +
> +	if (value & LTC3350_CHRG_STEPDOWN) {
> +		/* The chip remains in CV mode indefinitely, hence "full" */
> +		if (value & LTC3350_CHRG_CV)
> +			return POWER_SUPPLY_STATUS_FULL;
> +
> +		return POWER_SUPPLY_STATUS_CHARGING;
> +	}
> +
> +	/* Not in step down? Must be full then (never seen this) */
> +	return POWER_SUPPLY_STATUS_FULL;
> +};
> +
> +static int ltc3350_get_status(struct ltc3350_info *info, union power_supply_propval *val)
> +{
> +	unsigned int regval;
> +	int ret;
> +
> +	ret = regmap_read(info->regmap, LTC3350_REG_CHRG_STATUS, &regval);
> +	if (ret)
> +		return ret;
> +
> +	val->intval = ltc3350_state_decode(regval);
> +
> +	return 0;
> +}
> +
> +static int ltc3350_charge_status_decode(unsigned int value)
> +{
> +	if (!(value & LTC3350_CHRG_STEPDOWN))
> +		return POWER_SUPPLY_CHARGE_TYPE_NONE;
> +
> +	/* constant voltage is "topping off" */
> +	if (value & LTC3350_CHRG_CV)
> +		return POWER_SUPPLY_CHARGE_TYPE_TRICKLE;
> +
> +	/* input limiter */
> +	if (value & LTC3350_CHRG_INPUT_ILIM)
> +		return POWER_SUPPLY_CHARGE_TYPE_ADAPTIVE;
> +
> +	/* constant current is "fast" */
> +	if (value & LTC3350_CHRG_CI)
> +		return POWER_SUPPLY_CHARGE_TYPE_FAST;
> +
> +	return POWER_SUPPLY_CHARGE_TYPE_UNKNOWN;
> +}
> +
> +static int ltc3350_get_charge_type(struct ltc3350_info *info, union power_supply_propval *val)
> +{
> +	unsigned int regval;
> +	int ret;
> +
> +	ret = regmap_read(info->regmap, LTC3350_REG_CHRG_STATUS, &regval);
> +	if (ret)
> +		return ret;
> +
> +	val->intval = ltc3350_charge_status_decode(regval);
> +
> +	return 0;
> +}
> +
> +static int ltc3350_get_online(struct ltc3350_info *info, union power_supply_propval *val)
> +{
> +	unsigned int regval;
> +	int ret;
> +
> +	ret = regmap_read(info->regmap, LTC3350_REG_MON_STATUS, &regval);
> +	if (ret)
> +		return ret;
> +
> +	/* indicates if input voltage is sufficient to charge */
> +	val->intval = !!(regval & LTC3350_MON_POWER_RETURNED);
> +
> +	return 0;
> +}
> +
> +static int ltc3350_get_input_voltage(struct ltc3350_info *info, union power_supply_propval *val)
> +{
> +	unsigned int regval;
> +	int ret;
> +
> +	ret = regmap_read(info->regmap, LTC3350_REG_MEAS_VIN, &regval);
> +	if (ret)
> +		return ret;
> +
> +	/* 2.21mV/LSB */
> +	val->intval =  regval * 2210;
> +
> +	return 0;
> +}
> +
> +static int ltc3350_get_input_current(struct ltc3350_info *info, union power_supply_propval *val)
> +{
> +	unsigned int regval;
> +	int ret;
> +
> +	ret = regmap_read(info->regmap, LTC3350_REG_MEAS_IIN, &regval);
> +	if (ret)
> +		return ret;
> +
> +	/* 1.983µV/RSNSI amperes per LSB */
> +	ret = regval * 19830;
> +	ret /= info->rsnsi;
> +	ret *= 100;
> +
> +	val->intval = ret;
> +
> +	return 0;
> +}
> +
> +static int ltc3350_get_icharge(struct ltc3350_info *info, union power_supply_propval *val)
> +{
> +	unsigned int regval;
> +	int ret;
> +
> +	ret = regmap_read(info->regmap, LTC3350_REG_MEAS_ICHG, &regval);
> +	if (ret)
> +		return ret;
> +
> +	/* 1.983µV/RSNSC amperes per LSB */
> +	ret = regval * 19830;
> +	ret /= info->rsnsc;
> +	ret *= 100;
> +
> +	val->intval = ret;
> +
> +	return 0;
> +}
> +
> +static int ltc3350_get_icharge_max(struct ltc3350_info *info, union power_supply_propval *val)
> +{
> +	/* I_CHG(MAX) = 32mV / RSNSC (Ampere) */
> +	val->intval = 3200000000U / (info->rsnsc / 10);
> +
> +	return 0;
> +}
> +
> +static int ltc3350_get_iin_max(struct ltc3350_info *info, union power_supply_propval *val)
> +{
> +	/* I_IN(MAX) = 32mV / RSNSI (Ampere) */
> +	val->intval = 3200000000U / (info->rsnsi / 10);
> +
> +	return 0;
> +}
> +
> +
> +static int ltc3350_get_die_temp(struct ltc3350_info *info, unsigned int reg,
> +				union power_supply_propval *val)
> +{
> +	unsigned int regval;
> +	int ret;
> +
> +	ret = regmap_read(info->regmap, reg, &regval);
> +	if (ret)
> +		return ret;
> +
> +	/* 0.028°C per LSB – 251.4°C */
> +	ret = 280 * regval;
> +	ret /= 100; /* Centidegrees scale */
> +	ret -= 25140;
> +	val->intval = ret;
> +
> +	return 0;
> +}
> +
> +static int ltc3350_set_die_temp(struct ltc3350_info *info, unsigned int reg, int val)
> +{
> +	unsigned int regval;
> +	int ret;
> +
> +	/* 0.028°C per LSB – 251.4°C */
> +	regval = val + 25140;
> +	regval *= 100;
> +	regval /= 280;
> +
> +	ret = regmap_write(info->regmap, reg, regval);
> +	if (ret)
> +		return ret;
> +
> +	ltc3350_enable_alarm(info, reg);
> +	return 0;
> +}
> +
> +/* Custom properties */
> +
> +static ssize_t ltc3350_attr_show(struct device *dev,
> +				 struct device_attribute *attr, char *buf,
> +				 unsigned int reg, unsigned int scale)
> +{
> +	struct power_supply *psy = to_power_supply(dev);
> +	struct ltc3350_info *info = power_supply_get_drvdata(psy);
> +	unsigned int regval;
> +	int ret;
> +
> +	ret = regmap_read(info->regmap, reg, &regval);
> +	if (ret)
> +		return ret;
> +
> +	regval *= scale; /* Scale is in 10 μV units */

please keep custom uAPI consistent with the general uAPI and use µV.

> +	regval /= 10;
> +
> +	return sprintf(buf, "%u\n", regval);
> +}
> +
> +static ssize_t ltc3350_attr_store(struct device *dev, struct device_attribute *attr,
> +				  const char *buf, size_t count,
> +				  unsigned int reg, unsigned int scale)
> +{
> +	struct power_supply *psy = to_power_supply(dev);
> +	struct ltc3350_info *info = power_supply_get_drvdata(psy);
> +	unsigned long val;
> +	int ret;
> +
> +	ret = kstrtoul(buf, 10, &val);
> +	if (ret)
> +		return ret;
> +
> +	val *= 10;
> +	val = DIV_ROUND_CLOSEST(val, scale); /* Scale is in 10 μV units */

obviously also applied to writing.

> +
> +	ret = regmap_write(info->regmap, reg, val);
> +	if (ret)
> +		return ret;
> +
> +	/* When writing to one of the LVL registers, update the alarm mask */
> +	if (reg >= LTC3350_REG_CAP_UV_LVL && reg <= LTC3350_REG_CAP_LO_LVL)
> +		ltc3350_enable_alarm(info, reg);
> +
> +	return count;
> +}
> +
> +#define LTC3350_DEVICE_ATTR_RO(_name, _reg, _scale)				\
> +static ssize_t _name##_show(struct device *dev, struct device_attribute *attr,	\
> +			    char *buf)						\
> +{										\
> +	return ltc3350_attr_show(dev, attr, buf, _reg, _scale);			\
> +}										\
> +static DEVICE_ATTR_RO(_name)
> +
> +#define LTC3350_DEVICE_ATTR_RW(_name, _reg, _scale)				\
> +static ssize_t _name##_show(struct device *dev, struct device_attribute *attr,	\
> +			    char *buf)						\
> +{										\
> +	return ltc3350_attr_show(dev, attr, buf, _reg, _scale);			\
> +}										\
> +static ssize_t _name##_store(struct device *dev, struct device_attribute *attr, \
> +			     const char *buf, size_t count)			\
> +{										\
> +	return ltc3350_attr_store(dev, attr, buf, count, _reg, _scale);		\
> +}										\
> +static DEVICE_ATTR_RW(_name)
> +
> +/* Shunt voltage, 183.5μV per LSB */
> +LTC3350_DEVICE_ATTR_RW(vshunt, LTC3350_REG_VSHUNT, 1835);
> +
> +/* Single capacitor voltages, 183.5μV per LSB */
> +LTC3350_DEVICE_ATTR_RO(vcap1, LTC3350_REG_MEAS_VCAP1, 1835);
> +LTC3350_DEVICE_ATTR_RO(vcap2, LTC3350_REG_MEAS_VCAP2, 1835);
> +LTC3350_DEVICE_ATTR_RO(vcap3, LTC3350_REG_MEAS_VCAP3, 1835);
> +LTC3350_DEVICE_ATTR_RO(vcap4, LTC3350_REG_MEAS_VCAP4, 1835);
> +LTC3350_DEVICE_ATTR_RW(cap_uv, LTC3350_REG_CAP_UV_LVL, 1835);
> +LTC3350_DEVICE_ATTR_RW(cap_ov, LTC3350_REG_CAP_OV_LVL, 1835);
> +
> +/* General purpose input, 183.5μV per LSB */
> +LTC3350_DEVICE_ATTR_RO(gpi, LTC3350_REG_MEAS_GPI, 1835);
> +LTC3350_DEVICE_ATTR_RW(gpi_uv, LTC3350_REG_GPI_UV_LVL, 1835);
> +LTC3350_DEVICE_ATTR_RW(gpi_ov, LTC3350_REG_GPI_OV_LVL, 1835);
> +
> +/* Input voltage, 2.21mV per LSB */
> +LTC3350_DEVICE_ATTR_RO(vin, LTC3350_REG_MEAS_VIN, 22100);
> +LTC3350_DEVICE_ATTR_RW(vin_uv, LTC3350_REG_VIN_UV_LVL, 22100);
> +LTC3350_DEVICE_ATTR_RW(vin_ov, LTC3350_REG_VIN_OV_LVL, 22100);
> +
> +/* Capacitor stack voltage, 1.476 mV per LSB */
> +LTC3350_DEVICE_ATTR_RO(vcap, LTC3350_REG_MEAS_VCAP, 14760);
> +LTC3350_DEVICE_ATTR_RW(vcap_uv, LTC3350_REG_VCAP_UV_LVL, 14760);
> +LTC3350_DEVICE_ATTR_RW(vcap_ov, LTC3350_REG_VCAP_OV_LVL, 14760);

I suppose it would be sensible to expose this as a second
power_supply device of type battery with ltc3350_config.supplied_to
set to this second power_supply device.

Then you can map

LTC3350_REG_MEAS_VCAP -> VOLTAGE_NOW
LTC3350_REG_VCAP_UV_LVL -> VOLTAGE_MIN
LTC3350_REG_VCAP_OV_LVL -> VOLTAGE_MAX
LTC3350_REG_VSHUNT -> CURRENT_NOW
TECHNOLOGY = POWER_SUPPLY_TECHNOLOGY_CAPACITOR (new)

Also the single capacitor voltages are similar to per-cell voltage
information, so I think we should create generic properties for
that:

LTC3350_REG_NUM_CAPS   -> NUMBER_OF_CELLS (new)
LTC3350_REG_MEAS_VCAP1 -> CELL1_VOLTAGE_NOW (new)
LTC3350_REG_MEAS_VCAP2 -> CELL2_VOLTAGE_NOW (new)
LTC3350_REG_MEAS_VCAP3 -> CELL3_VOLTAGE_NOW (new)
LTC3350_REG_MEAS_VCAP4 -> CELL4_VOLTAGE_NOW (new)
LTC3350_REG_CAP_UV_LVL -> CELL_VOLTAGE_MIN (new)
LTC3350_REG_CAP_OV_LVL -> CELL_VOLTAGE_MAX (new)

> +/* Output, 2.21mV per LSB */
> +LTC3350_DEVICE_ATTR_RO(vout, LTC3350_REG_MEAS_VOUT, 22100);
> +LTC3350_DEVICE_ATTR_RW(vout_uv, LTC3350_REG_VOUT_UV_LVL, 22100);
> +LTC3350_DEVICE_ATTR_RW(vout_ov, LTC3350_REG_VOUT_OV_LVL, 22100);
> +
> +static ssize_t num_caps_show(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> +	struct power_supply *psy = to_power_supply(dev);
> +	struct ltc3350_info *info = power_supply_get_drvdata(psy);
> +	unsigned int regval;
> +	int ret;
> +
> +	ret = regmap_read(info->regmap, LTC3350_REG_NUM_CAPS, &regval);
> +	if (ret)
> +		return ret;
> +
> +	return sprintf(buf, "%u\n", regval + 1);
> +}
> +static DEVICE_ATTR_RO(num_caps);
> +
> +static ssize_t charge_status_show(struct device *dev, struct device_attribute *attr, char *buf)
> +{
> +	struct power_supply *psy = to_power_supply(dev);
> +	struct ltc3350_info *info = power_supply_get_drvdata(psy);
> +	unsigned int regval;
> +	int ret;
> +
> +	ret = regmap_read(info->regmap, LTC3350_REG_CHRG_STATUS, &regval);
> +	if (ret)
> +		return ret;
> +
> +	return sprintf(buf, "0x%x\n", regval);
> +}
> +static DEVICE_ATTR_RO(charge_status);
> +
> +static struct attribute *ltc3350_sysfs_entries[] = {
> +	&dev_attr_vshunt.attr,
> +	&dev_attr_vcap1.attr,
> +	&dev_attr_vcap2.attr,
> +	&dev_attr_vcap3.attr,
> +	&dev_attr_vcap4.attr,
> +	&dev_attr_cap_uv.attr,
> +	&dev_attr_cap_ov.attr,
> +	&dev_attr_gpi.attr,
> +	&dev_attr_gpi_uv.attr,
> +	&dev_attr_gpi_ov.attr,
> +	&dev_attr_vin.attr,
> +	&dev_attr_vin_uv.attr,
> +	&dev_attr_vin_ov.attr,
> +	&dev_attr_vcap.attr,
> +	&dev_attr_vcap_uv.attr,
> +	&dev_attr_vcap_ov.attr,
> +	&dev_attr_vout.attr,
> +	&dev_attr_vout_uv.attr,
> +	&dev_attr_vout_ov.attr,
> +	&dev_attr_num_caps.attr,
> +	&dev_attr_charge_status.attr,
> +	NULL,
> +};

Exposing these to sysfs makes them ABI and ABI needs to be
documented in Documentation/ABI, see for example

Documentation/ABI/testing/sysfs-class-power-rt9467

> +static const struct attribute_group ltc3350_attr_group = {
> +	.name	= NULL,	/* put in device directory */
> +	.attrs	= ltc3350_sysfs_entries,
> +};
> +
> +static const struct attribute_group *ltc3350_attr_groups[] = {
> +	&ltc3350_attr_group,
> +	NULL,
> +};
> +
> +static int ltc3350_get_property(struct power_supply *psy, enum power_supply_property psp,
> +				union power_supply_propval *val)
> +{
> +	struct ltc3350_info *info = power_supply_get_drvdata(psy);
> +
> +	switch (psp) {
> +	case POWER_SUPPLY_PROP_STATUS:
> +		return ltc3350_get_status(info, val);
> +	case POWER_SUPPLY_PROP_CHARGE_TYPE:
> +		return ltc3350_get_charge_type(info, val);
> +	case POWER_SUPPLY_PROP_ONLINE:
> +		return ltc3350_get_online(info, val);
> +	case POWER_SUPPLY_PROP_VOLTAGE_NOW:
> +		return ltc3350_get_input_voltage(info, val);
> +	case POWER_SUPPLY_PROP_CURRENT_NOW:
> +		return ltc3350_get_input_current(info, val);
> +	case POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT:
> +		return ltc3350_get_icharge(info, val);
> +	case POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT_MAX:
> +		return ltc3350_get_icharge_max(info, val);
> +	case POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT:
> +		return ltc3350_get_iin_max(info, val);
> +	case POWER_SUPPLY_PROP_TEMP:
> +		return ltc3350_get_die_temp(info, LTC3350_REG_MEAS_DTEMP, val);
> +	case POWER_SUPPLY_PROP_TEMP_ALERT_MIN:
> +		return ltc3350_get_die_temp(info, LTC3350_REG_DTEMP_COLD_LVL, val);
> +	case POWER_SUPPLY_PROP_TEMP_ALERT_MAX:
> +		return ltc3350_get_die_temp(info, LTC3350_REG_DTEMP_HOT_LVL, val);
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int ltc3350_set_property(struct power_supply *psy, enum power_supply_property psp,
> +				const union power_supply_propval *val)
> +{
> +	struct ltc3350_info *info = power_supply_get_drvdata(psy);
> +
> +	switch (psp) {
> +	case POWER_SUPPLY_PROP_TEMP_ALERT_MIN:
> +		return ltc3350_set_die_temp(info, LTC3350_REG_DTEMP_COLD_LVL, val->intval);
> +	case POWER_SUPPLY_PROP_TEMP_ALERT_MAX:
> +		return ltc3350_set_die_temp(info, LTC3350_REG_DTEMP_HOT_LVL, val->intval);
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static int ltc3350_property_is_writeable(struct power_supply *psy, enum power_supply_property psp)
> +{
> +	switch (psp) {
> +	case POWER_SUPPLY_PROP_TEMP_ALERT_MIN:
> +	case POWER_SUPPLY_PROP_TEMP_ALERT_MAX:
> +		return 1;
> +	default:
> +		return 0;
> +	}
> +}
> +
> +/* Charger power supply property routines */
> +static enum power_supply_property ltc3350_properties[] = {
> +	POWER_SUPPLY_PROP_STATUS,
> +	POWER_SUPPLY_PROP_CHARGE_TYPE,
> +	POWER_SUPPLY_PROP_ONLINE,
> +	POWER_SUPPLY_PROP_VOLTAGE_NOW,
> +	POWER_SUPPLY_PROP_CURRENT_NOW,
> +	POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT,
> +	POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT_MAX,
> +	POWER_SUPPLY_PROP_INPUT_CURRENT_LIMIT,
> +	POWER_SUPPLY_PROP_TEMP,
> +	POWER_SUPPLY_PROP_TEMP_ALERT_MIN,
> +	POWER_SUPPLY_PROP_TEMP_ALERT_MAX,
> +};
> +
> +static const struct power_supply_desc ltc3350_desc = {
> +	.name		= "ltc3350",
> +	.type		= POWER_SUPPLY_TYPE_MAINS,
> +	.properties	= ltc3350_properties,
> +	.num_properties	= ARRAY_SIZE(ltc3350_properties),
> +	.get_property	= ltc3350_get_property,
> +	.set_property	= ltc3350_set_property,
> +	.property_is_writeable = ltc3350_property_is_writeable,
> +};
> +
> +static bool ltc3350_is_writeable_reg(struct device *dev, unsigned int reg)
> +{
> +	/* all registers up to this one are writeable */
> +	return reg < LTC3350_REG_NUM_CAPS;
> +}
> +
> +static bool ltc3350_is_volatile_reg(struct device *dev, unsigned int reg)
> +{
> +	/* read-only status registers and self-clearing register */
> +	return reg > LTC3350_REG_NUM_CAPS || reg == LTC3350_REG_CLR_ALARMS;
> +}
> +
> +static const struct regmap_config ltc3350_regmap_config = {
> +	.reg_bits	= 8,
> +	.val_bits	= 16,
> +	.val_format_endian = REGMAP_ENDIAN_LITTLE,
> +	.writeable_reg	= ltc3350_is_writeable_reg,
> +	.volatile_reg	= ltc3350_is_volatile_reg,
> +	.max_register	= LTC3350_REG_MEAS_DTEMP,
> +	.cache_type	= REGCACHE_MAPLE,
> +};
> +
> +static int ltc3350_probe(struct i2c_client *client)
> +{
> +	struct i2c_adapter *adapter = client->adapter;
> +	struct device *dev = &client->dev;
> +	struct ltc3350_info *info;
> +	struct power_supply_config ltc3350_config = {};
> +	int ret;
> +
> +	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WORD_DATA)) {
> +		dev_err(dev, "No support for SMBUS_WORD_DATA\n");
> +		return -ENODEV;
> +	}

return dev_err_probe(dev, -ENODEV, "No support for SMBUS_WORD_DATA\n");

But I think this can just be dropped. devm_regmap_init_i2c() should
generate an error, if the i2c adapter requirements are not met.

> +	info = devm_kzalloc(dev, sizeof(*info), GFP_KERNEL);
> +	if (!info)
> +		return -ENOMEM;
> +
> +	info->client = client;
> +	i2c_set_clientdata(client, info);
> +
> +	info->regmap = devm_regmap_init_i2c(client, &ltc3350_regmap_config);
> +	if (IS_ERR(info->regmap)) {
> +		dev_err(dev, "Failed to initialize register map\n");
> +		return PTR_ERR(info->regmap);
> +	}

dev_err_probe()

> +
> +	ret = device_property_read_u32(dev, "lltc,rsnsc-micro-ohms",
> +				       &info->rsnsc);
> +	if (ret) {
> +		dev_err(dev, "Missing lltc,rsnsc-micro-ohms property\n");
> +		return ret;
> +	}

dev_err_probe()

> +	if (!info->rsnsc)
> +		return -EINVAL;
> +
> +	ret = device_property_read_u32(dev, "lltc,rsnsi-micro-ohms",
> +				       &info->rsnsi);
> +	if (ret) {
> +		dev_err(dev, "Missing lltc,rsnsi-micro-ohms property\n");
> +		return ret;
> +	}

dev_err_probe()

> +	if (!info->rsnsi)
> +		return -EINVAL;
> +
> +	/* Clear and disable all interrupt sources*/
> +	ret = regmap_write(info->regmap, LTC3350_REG_CLR_ALARMS, 0xFFFF);
> +	if (ret) {
> +		dev_err(dev, "Failed to write configuration\n");
> +		return ret;
> +	}

dev_err_probe()

> +	regmap_write(info->regmap, LTC3350_REG_MSK_ALARMS, 0);
> +	regmap_write(info->regmap, LTC3350_REG_MSK_MON_STATUS, 0);
> +
> +	ltc3350_config.of_node = dev->of_node;

replace with

ltc3350_config.fwnode = dev_fwnode(dev);

> +	ltc3350_config.drv_data = info;
> +	ltc3350_config.attr_grp = ltc3350_attr_groups;
> +
> +	info->charger = devm_power_supply_register(dev, &ltc3350_desc,
> +						   &ltc3350_config);
> +	if (IS_ERR(info->charger)) {
> +		dev_err(dev, "Failed to register charger\n");
> +		return PTR_ERR(info->charger);
> +	}

dev_err_probe()

> +
> +	/* Enable interrupts on status changes */
> +	regmap_write(info->regmap, LTC3350_REG_MSK_MON_STATUS,
> +		     LTC3350_MON_POWER_FAILED | LTC3350_MON_POWER_RETURNED);
> +
> +	return 0;
> +}
> +
> +static void ltc3350_alert(struct i2c_client *client, enum i2c_alert_protocol type,
> +			  unsigned int flag)
> +{
> +	struct ltc3350_info *info = i2c_get_clientdata(client);
> +
> +	if (type != I2C_PROTOCOL_SMBUS_ALERT)
> +		return;
> +
> +	power_supply_changed(info->charger);
> +}
> +
> +static const struct i2c_device_id ltc3350_i2c_id_table[] = {
> +	{ "ltc3350", 0 },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(i2c, ltc3350_i2c_id_table);
> +
> +static const struct of_device_id ltc3350_of_match[] = {
> +	{ .compatible = "lltc,ltc3350", },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(of, ltc3350_of_match);
> +
> +static struct i2c_driver ltc3350_driver = {
> +	.probe		= ltc3350_probe,
> +	.alert		= ltc3350_alert,
> +	.id_table	= ltc3350_i2c_id_table,
> +	.driver = {
> +		.name		= "ltc3350-charger",
> +		.of_match_table	= of_match_ptr(ltc3350_of_match),

Please check what of_match_ptr() does and then drop it :)

> +	},
> +};
> +module_i2c_driver(ltc3350_driver);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Mike Looijmans <mike.looijmans@topic.nl>");
> +MODULE_DESCRIPTION("LTC3350 charger driver");

Thanks for your patch,

-- Sebastian

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Re: [PATCH v3 2/2] power: supply: ltc3350-charger: Add driver

[Mike Looijmans]

Assume "yes, will do" to any feedback I've skipped.

On 10-04-2024 09:56, Sebastian Reichel wrote:
> Hi,
>
> On Tue, Apr 09, 2024 at 03:54:41PM +0200, Mike Looijmans wrote:
>> The LTC3350 is a backup power controller that can charge and monitor
>> a series stack of one to four supercapacitors.
>>
>> Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
>>
>> ---
> please share output of
> ./tools/testing/selftests/power_supply/test_power_supply_properties.sh
> below the fold with your next submission. It's useful for verifying,
> that you got the unit scaling correct for the standard properties :)

Will do. Did a quick run on the driver as it is now, that yields the 
following output:

(Any thoughts on the "arithmetic syntax error" messages?)

# ./test_power_supply_properties.sh
TAP version 13
./test_power_supply_properties.sh: line 26: arithmetic syntax error
1..
# Testing device ltc3350
ok 1 ltc3350.exists
ok 2 ltc3350.uevent.NAME
ok 3 ltc3350.sysfs.type
ok 4 ltc3350.uevent.TYPE
ok 5 ltc3350.sysfs.usb_type # SKIP
# Reported: '1' ()
ok 6 ltc3350.sysfs.online
ok 7 ltc3350.sysfs.present # SKIP
# Reported: 'Full'
ok 8 ltc3350.sysfs.status
ok 9 ltc3350.sysfs.capacity # SKIP
ok 10 ltc3350.sysfs.capacity_level # SKIP
ok 11 ltc3350.sysfs.model_name # SKIP
ok 12 ltc3350.sysfs.manufacturer # SKIP
ok 13 ltc3350.sysfs.serial_number # SKIP
ok 14 ltc3350.sysfs.technology # SKIP
ok 15 ltc3350.sysfs.cycle_count # SKIP
ok 16 ltc3350.sysfs.scope # SKIP
# Reported: '3200000' uA (3200 mA)
ok 17 ltc3350.sysfs.input_current_limit
ok 18 ltc3350.sysfs.input_voltage_limit # SKIP
# Reported: '23828220' uV (23.8282 V)
ok 19 ltc3350.sysfs.voltage_now
ok 20 ltc3350.sysfs.voltage_min # SKIP
ok 21 ltc3350.sysfs.voltage_max # SKIP
ok 22 ltc3350.sysfs.voltage_min_design # SKIP
ok 23 ltc3350.sysfs.voltage_max_design # SKIP
# Reported: '711600' uA (711.6 mA)
ok 24 ltc3350.sysfs.current_now
ok 25 ltc3350.sysfs.current_max # SKIP
ok 26 ltc3350.sysfs.charge_now # SKIP
ok 27 ltc3350.sysfs.charge_full # SKIP
ok 28 ltc3350.sysfs.charge_full_design # SKIP
ok 29 ltc3350.sysfs.power_now # SKIP
ok 30 ltc3350.sysfs.energy_now # SKIP
ok 31 ltc3350.sysfs.energy_full # SKIP
ok 32 ltc3350.sysfs.energy_full_design # SKIP
ok 33 ltc3350.sysfs.energy_full_design # SKIP
# Totals: pass:9 fail:0 xfail:0 xpass:0 skip:24 error:0
./test_power_supply_properties.sh: line 102: arithmetic syntax error

>> (no changes since v2)
>>
>> Changes in v2:
>> Duplicate "vin_ov" and "vin_uv" attributes
>>
>>   drivers/power/supply/Kconfig           |  10 +
>>   drivers/power/supply/Makefile          |   1 +
>>   drivers/power/supply/ltc3350-charger.c | 718 +++++++++++++++++++++++++
>>   3 files changed, 729 insertions(+)
>>   create mode 100644 drivers/power/supply/ltc3350-charger.c
>>
>> +/* Custom properties */
>> +
>> +static ssize_t ltc3350_attr_show(struct device *dev,
>> +				 struct device_attribute *attr, char *buf,
>> +				 unsigned int reg, unsigned int scale)
>> +{
>> +	struct power_supply *psy = to_power_supply(dev);
>> +	struct ltc3350_info *info = power_supply_get_drvdata(psy);
>> +	unsigned int regval;
>> +	int ret;
>> +
>> +	ret = regmap_read(info->regmap, reg, &regval);
>> +	if (ret)
>> +		return ret;
>> +
>> +	regval *= scale; /* Scale is in 10 μV units */
> please keep custom uAPI consistent with the general uAPI and use µV.

I'll amend the comment to clarify that this is about the scale factor 
passed into this method. This prevents overflow while keeping all 
calculations in 32 bits.


>
>> +	regval /= 10;
>> +
>> +	return sprintf(buf, "%u\n", regval);
>> +}
>> +
>> +static ssize_t ltc3350_attr_store(struct device *dev, struct device_attribute *attr,
>> +				  const char *buf, size_t count,
>> +				  unsigned int reg, unsigned int scale)
>> +{
>> +	struct power_supply *psy = to_power_supply(dev);
>> +	struct ltc3350_info *info = power_supply_get_drvdata(psy);
>> +	unsigned long val;
>> +	int ret;
>> +
>> +	ret = kstrtoul(buf, 10, &val);
>> +	if (ret)
>> +		return ret;
>> +
>> +	val *= 10;
>> +	val = DIV_ROUND_CLOSEST(val, scale); /* Scale is in 10 μV units */
> obviously also applied to writing.
>
>> +
>> +	ret = regmap_write(info->regmap, reg, val);
>> +	if (ret)
>> +		return ret;
>> +
>> +	/* When writing to one of the LVL registers, update the alarm mask */
>> +	if (reg >= LTC3350_REG_CAP_UV_LVL && reg <= LTC3350_REG_CAP_LO_LVL)
>> +		ltc3350_enable_alarm(info, reg);
>> +
>> +	return count;
>> +}
>> +
>> +#define LTC3350_DEVICE_ATTR_RO(_name, _reg, _scale)				\
>> +static ssize_t _name##_show(struct device *dev, struct device_attribute *attr,	\
>> +			    char *buf)						\
>> +{										\
>> +	return ltc3350_attr_show(dev, attr, buf, _reg, _scale);			\
>> +}										\
>> +static DEVICE_ATTR_RO(_name)
>> +
>> +#define LTC3350_DEVICE_ATTR_RW(_name, _reg, _scale)				\
>> +static ssize_t _name##_show(struct device *dev, struct device_attribute *attr,	\
>> +			    char *buf)						\
>> +{										\
>> +	return ltc3350_attr_show(dev, attr, buf, _reg, _scale);			\
>> +}										\
>> +static ssize_t _name##_store(struct device *dev, struct device_attribute *attr, \
>> +			     const char *buf, size_t count)			\
>> +{										\
>> +	return ltc3350_attr_store(dev, attr, buf, count, _reg, _scale);		\
>> +}										\
>> +static DEVICE_ATTR_RW(_name)
>> +
>> +/* Shunt voltage, 183.5μV per LSB */
>> +LTC3350_DEVICE_ATTR_RW(vshunt, LTC3350_REG_VSHUNT, 1835);
>> +
>> +/* Single capacitor voltages, 183.5μV per LSB */
>> +LTC3350_DEVICE_ATTR_RO(vcap1, LTC3350_REG_MEAS_VCAP1, 1835);
>> +LTC3350_DEVICE_ATTR_RO(vcap2, LTC3350_REG_MEAS_VCAP2, 1835);
>> +LTC3350_DEVICE_ATTR_RO(vcap3, LTC3350_REG_MEAS_VCAP3, 1835);
>> +LTC3350_DEVICE_ATTR_RO(vcap4, LTC3350_REG_MEAS_VCAP4, 1835);
>> +LTC3350_DEVICE_ATTR_RW(cap_uv, LTC3350_REG_CAP_UV_LVL, 1835);
>> +LTC3350_DEVICE_ATTR_RW(cap_ov, LTC3350_REG_CAP_OV_LVL, 1835);
>> +
>> +/* General purpose input, 183.5μV per LSB */
>> +LTC3350_DEVICE_ATTR_RO(gpi, LTC3350_REG_MEAS_GPI, 1835);
>> +LTC3350_DEVICE_ATTR_RW(gpi_uv, LTC3350_REG_GPI_UV_LVL, 1835);
>> +LTC3350_DEVICE_ATTR_RW(gpi_ov, LTC3350_REG_GPI_OV_LVL, 1835);
>> +
>> +/* Input voltage, 2.21mV per LSB */
>> +LTC3350_DEVICE_ATTR_RO(vin, LTC3350_REG_MEAS_VIN, 22100);
>> +LTC3350_DEVICE_ATTR_RW(vin_uv, LTC3350_REG_VIN_UV_LVL, 22100);
>> +LTC3350_DEVICE_ATTR_RW(vin_ov, LTC3350_REG_VIN_OV_LVL, 22100);
>> +
>> +/* Capacitor stack voltage, 1.476 mV per LSB */
>> +LTC3350_DEVICE_ATTR_RO(vcap, LTC3350_REG_MEAS_VCAP, 14760);
>> +LTC3350_DEVICE_ATTR_RW(vcap_uv, LTC3350_REG_VCAP_UV_LVL, 14760);
>> +LTC3350_DEVICE_ATTR_RW(vcap_ov, LTC3350_REG_VCAP_OV_LVL, 14760);
> I suppose it would be sensible to expose this as a second
> power_supply device of type battery with ltc3350_config.supplied_to
> set to this second power_supply device.
>
> Then you can map
>
> LTC3350_REG_MEAS_VCAP -> VOLTAGE_NOW
> LTC3350_REG_VCAP_UV_LVL -> VOLTAGE_MIN
> LTC3350_REG_VCAP_OV_LVL -> VOLTAGE_MAX
> LTC3350_REG_VSHUNT -> CURRENT_NOW
> TECHNOLOGY = POWER_SUPPLY_TECHNOLOGY_CAPACITOR (new)

Makes sense.

Should I create a separate patch that adds the new properties?


> Also the single capacitor voltages are similar to per-cell voltage
> information, so I think we should create generic properties for
> that:
>
> LTC3350_REG_NUM_CAPS   -> NUMBER_OF_CELLS (new)
> LTC3350_REG_MEAS_VCAP1 -> CELL1_VOLTAGE_NOW (new)
> LTC3350_REG_MEAS_VCAP2 -> CELL2_VOLTAGE_NOW (new)
> LTC3350_REG_MEAS_VCAP3 -> CELL3_VOLTAGE_NOW (new)
> LTC3350_REG_MEAS_VCAP4 -> CELL4_VOLTAGE_NOW (new)
> LTC3350_REG_CAP_UV_LVL -> CELL_VOLTAGE_MIN (new)
> LTC3350_REG_CAP_OV_LVL -> CELL_VOLTAGE_MAX (new)
>
> ...

>> +
>> +static int ltc3350_probe(struct i2c_client *client)
>> +{
>> +	struct i2c_adapter *adapter = client->adapter;
>> +	struct device *dev = &client->dev;
>> +	struct ltc3350_info *info;
>> +	struct power_supply_config ltc3350_config = {};
>> +	int ret;
>> +
>> +	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WORD_DATA)) {
>> +		dev_err(dev, "No support for SMBUS_WORD_DATA\n");
>> +		return -ENODEV;
>> +	}
> return dev_err_probe(dev, -ENODEV, "No support for SMBUS_WORD_DATA\n");
>
> But I think this can just be dropped. devm_regmap_init_i2c() should
> generate an error, if the i2c adapter requirements are not met.

It's quite interesting to see what other drivers do here. Most report a 
message, and there's no consensus on the value returned.


>> +	info = devm_kzalloc(dev, sizeof(*info), GFP_KERNEL);
>> +	if (!info)
>> +		return -ENOMEM;
>> +
>> +	info->client = client;
>> +	i2c_set_clientdata(client, info);
>> +
>> +	info->regmap = devm_regmap_init_i2c(client, &ltc3350_regmap_config);
>> +	if (IS_ERR(info->regmap)) {
>> +		dev_err(dev, "Failed to initialize register map\n");
>> +		return PTR_ERR(info->regmap);
>> +	}
> dev_err_probe()
>
>> +
>> +	ret = device_property_read_u32(dev, "lltc,rsnsc-micro-ohms",
>> +				       &info->rsnsc);
>> +	if (ret) {
>> +		dev_err(dev, "Missing lltc,rsnsc-micro-ohms property\n");
>> +		return ret;
>> +	}
> dev_err_probe()
>
>> +	if (!info->rsnsc)
>> +		return -EINVAL;
>> +
>> +	ret = device_property_read_u32(dev, "lltc,rsnsi-micro-ohms",
>> +				       &info->rsnsi);
>> +	if (ret) {
>> +		dev_err(dev, "Missing lltc,rsnsi-micro-ohms property\n");
>> +		return ret;
>> +	}
> dev_err_probe()
>
>> +	if (!info->rsnsi)
>> +		return -EINVAL;
>> +
>> +	/* Clear and disable all interrupt sources*/
>> +	ret = regmap_write(info->regmap, LTC3350_REG_CLR_ALARMS, 0xFFFF);
>> +	if (ret) {
>> +		dev_err(dev, "Failed to write configuration\n");
>> +		return ret;
>> +	}
> dev_err_probe()
>
>> +	regmap_write(info->regmap, LTC3350_REG_MSK_ALARMS, 0);
>> +	regmap_write(info->regmap, LTC3350_REG_MSK_MON_STATUS, 0);
>> +
>> +	ltc3350_config.of_node = dev->of_node;
> replace with
>
> ltc3350_config.fwnode = dev_fwnode(dev);
>
>> +	ltc3350_config.drv_data = info;
>> +	ltc3350_config.attr_grp = ltc3350_attr_groups;
>> +
>> +	info->charger = devm_power_supply_register(dev, &ltc3350_desc,
>> +						   &ltc3350_config);
>> +	if (IS_ERR(info->charger)) {
>> +		dev_err(dev, "Failed to register charger\n");
>> +		return PTR_ERR(info->charger);
>> +	}
> dev_err_probe()
>
>> +
>> +	/* Enable interrupts on status changes */
>> +	regmap_write(info->regmap, LTC3350_REG_MSK_MON_STATUS,
>> +		     LTC3350_MON_POWER_FAILED | LTC3350_MON_POWER_RETURNED);
>> +
>> +	return 0;
>> +}
>> +
>> +static void ltc3350_alert(struct i2c_client *client, enum i2c_alert_protocol type,
>> +			  unsigned int flag)
>> +{
>> +	struct ltc3350_info *info = i2c_get_clientdata(client);
>> +
>> +	if (type != I2C_PROTOCOL_SMBUS_ALERT)
>> +		return;
>> +
>> +	power_supply_changed(info->charger);
>> +}
>> +
>> +static const struct i2c_device_id ltc3350_i2c_id_table[] = {
>> +	{ "ltc3350", 0 },
>> +	{ },
>> +};
>> +MODULE_DEVICE_TABLE(i2c, ltc3350_i2c_id_table);
>> +
>> +static const struct of_device_id ltc3350_of_match[] = {
>> +	{ .compatible = "lltc,ltc3350", },
>> +	{ },
>> +};
>> +MODULE_DEVICE_TABLE(of, ltc3350_of_match);
>> +
>> +static struct i2c_driver ltc3350_driver = {
>> +	.probe		= ltc3350_probe,
>> +	.alert		= ltc3350_alert,
>> +	.id_table	= ltc3350_i2c_id_table,
>> +	.driver = {
>> +		.name		= "ltc3350-charger",
>> +		.of_match_table	= of_match_ptr(ltc3350_of_match),
> Please check what of_match_ptr() does and then drop it :)

Interesting :)


>
>> +	},
>> +};
>> +module_i2c_driver(ltc3350_driver);
>> +
>> +MODULE_LICENSE("GPL");
>> +MODULE_AUTHOR("Mike Looijmans <mike.looijmans@topic.nl>");
>> +MODULE_DESCRIPTION("LTC3350 charger driver");
> Thanks for your patch,
>
> -- Sebastian


-- 
Mike Looijmans
System Expert

TOPIC Embedded Products B.V.
Materiaalweg 4, 5681 RJ Best
The Netherlands

T: +31 (0) 499 33 69 69
E: mike.looijmans@topic.nl
W: www.topic.nl

Re: [PATCH v3 2/2] power: supply: ltc3350-charger: Add driver

[Sebastian Reichel]

[-- Attachment #1: Type: text/plain, Size: 6427 bytes --]

[+cc Nicolas]

Hello Mike,

On Fri, Apr 12, 2024 at 08:53:58AM +0200, Mike Looijmans wrote:
> > please share output of
> > ./tools/testing/selftests/power_supply/test_power_supply_properties.sh
> > below the fold with your next submission. It's useful for verifying,
> > that you got the unit scaling correct for the standard properties :)
> 
> Will do. Did a quick run on the driver as it is now, that yields the
> following output:
> 
> (Any thoughts on the "arithmetic syntax error" messages?)

The script contains some bash specific shell extensions and should
use /bin/bash instead of /bin/sh in the shebang. Just call it with
/bin/bash ./tools/testing/... and you should get rid of them :)

Nicolas, do you want to send a fix for that to Shuah with Reported-by
from Mike?

[...]

> # Reported: '1' ()
> ok 6 ltc3350.sysfs.online

[...]

> # Reported: '711600' uA (711.6 mA)
> ok 24 ltc3350.sysfs.current_now

So it's full, but still getting charged with 0.7 Amps at ~23V
(i.e. 16W)? That seems quite high.

[...]

> > > +static ssize_t ltc3350_attr_show(struct device *dev,
> > > +				 struct device_attribute *attr, char *buf,
> > > +				 unsigned int reg, unsigned int scale)
> > > +{
> > > +	struct power_supply *psy = to_power_supply(dev);
> > > +	struct ltc3350_info *info = power_supply_get_drvdata(psy);
> > > +	unsigned int regval;
> > > +	int ret;
> > > +
> > > +	ret = regmap_read(info->regmap, reg, &regval);
> > > +	if (ret)
> > > +		return ret;
> > > +
> > > +	regval *= scale; /* Scale is in 10 μV units */
> > please keep custom uAPI consistent with the general uAPI and use µV.
> 
> I'll amend the comment to clarify that this is about the scale factor passed
> into this method. This prevents overflow while keeping all calculations in
> 32 bits.

ack

[...]

> > > +/* Shunt voltage, 183.5μV per LSB */
> > > +LTC3350_DEVICE_ATTR_RW(vshunt, LTC3350_REG_VSHUNT, 1835);
> > > +
> > > +/* Single capacitor voltages, 183.5μV per LSB */
> > > +LTC3350_DEVICE_ATTR_RO(vcap1, LTC3350_REG_MEAS_VCAP1, 1835);
> > > +LTC3350_DEVICE_ATTR_RO(vcap2, LTC3350_REG_MEAS_VCAP2, 1835);
> > > +LTC3350_DEVICE_ATTR_RO(vcap3, LTC3350_REG_MEAS_VCAP3, 1835);
> > > +LTC3350_DEVICE_ATTR_RO(vcap4, LTC3350_REG_MEAS_VCAP4, 1835);
> > > +LTC3350_DEVICE_ATTR_RW(cap_uv, LTC3350_REG_CAP_UV_LVL, 1835);
> > > +LTC3350_DEVICE_ATTR_RW(cap_ov, LTC3350_REG_CAP_OV_LVL, 1835);
> > > +
> > > +/* General purpose input, 183.5μV per LSB */
> > > +LTC3350_DEVICE_ATTR_RO(gpi, LTC3350_REG_MEAS_GPI, 1835);
> > > +LTC3350_DEVICE_ATTR_RW(gpi_uv, LTC3350_REG_GPI_UV_LVL, 1835);
> > > +LTC3350_DEVICE_ATTR_RW(gpi_ov, LTC3350_REG_GPI_OV_LVL, 1835);
> > > +
> > > +/* Input voltage, 2.21mV per LSB */
> > > +LTC3350_DEVICE_ATTR_RO(vin, LTC3350_REG_MEAS_VIN, 22100);
> > > +LTC3350_DEVICE_ATTR_RW(vin_uv, LTC3350_REG_VIN_UV_LVL, 22100);
> > > +LTC3350_DEVICE_ATTR_RW(vin_ov, LTC3350_REG_VIN_OV_LVL, 22100);
> > > +
> > > +/* Capacitor stack voltage, 1.476 mV per LSB */
> > > +LTC3350_DEVICE_ATTR_RO(vcap, LTC3350_REG_MEAS_VCAP, 14760);
> > > +LTC3350_DEVICE_ATTR_RW(vcap_uv, LTC3350_REG_VCAP_UV_LVL, 14760);
> > > +LTC3350_DEVICE_ATTR_RW(vcap_ov, LTC3350_REG_VCAP_OV_LVL, 14760);
> > I suppose it would be sensible to expose this as a second
> > power_supply device of type battery with ltc3350_config.supplied_to
> > set to this second power_supply device.
> > 
> > Then you can map
> > 
> > LTC3350_REG_MEAS_VCAP -> VOLTAGE_NOW
> > LTC3350_REG_VCAP_UV_LVL -> VOLTAGE_MIN
> > LTC3350_REG_VCAP_OV_LVL -> VOLTAGE_MAX
> > LTC3350_REG_VSHUNT -> CURRENT_NOW
> > TECHNOLOGY = POWER_SUPPLY_TECHNOLOGY_CAPACITOR (new)
> 
> Makes sense.
> 
> Should I create a separate patch that adds the new properties?

Yes, make it one extra patch adding POWER_SUPPLY_TECHNOLOGY_CAPACITOR
and one extra patch for the cell information properties. Also do not
forget to update all necessary files:

 * Documentation/ABI/testing/sysfs-class-power
 * include/linux/power_supply.h
 * drivers/power/supply/power_supply_sysfs.c

> > Also the single capacitor voltages are similar to per-cell voltage
> > information, so I think we should create generic properties for
> > that:
> > 
> > LTC3350_REG_NUM_CAPS   -> NUMBER_OF_CELLS (new)
> > LTC3350_REG_MEAS_VCAP1 -> CELL1_VOLTAGE_NOW (new)
> > LTC3350_REG_MEAS_VCAP2 -> CELL2_VOLTAGE_NOW (new)
> > LTC3350_REG_MEAS_VCAP3 -> CELL3_VOLTAGE_NOW (new)
> > LTC3350_REG_MEAS_VCAP4 -> CELL4_VOLTAGE_NOW (new)
> > LTC3350_REG_CAP_UV_LVL -> CELL_VOLTAGE_MIN (new)
> > LTC3350_REG_CAP_OV_LVL -> CELL_VOLTAGE_MAX (new)
> > 
> > ...

After re-reading it: This only works for serial cells, but not for
parallel ones. While it's technically not possible to measure
parallel cells, it might be desired to expose the exact
configuration at some point. Thus it should be
NUMBER_OF_SERIAL_CELLS. Also the documentation for
CELL<X>_VOLTAGE_NOW should mention that this might measure more than
one cell, if there are multiple cells connected in parallel.

[...]

> > > +
> > > +static int ltc3350_probe(struct i2c_client *client)
> > > +{
> > > +	struct i2c_adapter *adapter = client->adapter;
> > > +	struct device *dev = &client->dev;
> > > +	struct ltc3350_info *info;
> > > +	struct power_supply_config ltc3350_config = {};
> > > +	int ret;
> > > +
> > > +	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WORD_DATA)) {
> > > +		dev_err(dev, "No support for SMBUS_WORD_DATA\n");
> > > +		return -ENODEV;
> > > +	}
> > return dev_err_probe(dev, -ENODEV, "No support for SMBUS_WORD_DATA\n");
> > 
> > But I think this can just be dropped. devm_regmap_init_i2c() should
> > generate an error, if the i2c adapter requirements are not met.
> 
> It's quite interesting to see what other drivers do here. Most report a
> message, and there's no consensus on the value returned.

I checked and devm_regmap_init_i2c() calls into regmap_get_i2c_bus()
and that contains the same check. If it fails, the bus will not be
found and the function returns -ENOTSUPP. It should be fine to remove
the driver specific extra handling with the error being printed for
devm_regmap_init_i2c(). Considering this is mostly a hardware sanity
check, I would expect this error to only happen on developer
systems. A developer should be able to figure out what that means.

Greetings,

-- Sebastian

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Re: [PATCH v3 2/2] power: supply: ltc3350-charger: Add driver

[Mike Looijmans]

On 14-04-2024 19:29, Sebastian Reichel wrote:
> [+cc Nicolas]
>
> Hello Mike,
>
> On Fri, Apr 12, 2024 at 08:53:58AM +0200, Mike Looijmans wrote:
>>> please share output of
>>> ./tools/testing/selftests/power_supply/test_power_supply_properties.sh
>>> below the fold with your next submission. It's useful for verifying,
>>> that you got the unit scaling correct for the standard properties :)
>> Will do. Did a quick run on the driver as it is now, that yields the
>> following output:
>>
>> (Any thoughts on the "arithmetic syntax error" messages?)
> The script contains some bash specific shell extensions and should
> use /bin/bash instead of /bin/sh in the shebang. Just call it with
> /bin/bash ./tools/testing/... and you should get rid of them :)

Yeah, installing full bash (instead of busybox ash) on the board fixes 
these messages.


>
> Nicolas, do you want to send a fix for that to Shuah with Reported-by
> from Mike?
>
> [...]
>
>> # Reported: '1' ()
>> ok 6 ltc3350.sysfs.online
> [...]
>
>> # Reported: '711600' uA (711.6 mA)
>> ok 24 ltc3350.sysfs.current_now
> So it's full, but still getting charged with 0.7 Amps at ~23V
> (i.e. 16W)? That seems quite high.

The "current" is also feeding the system, not just the capacitors. 
(panel backlight being the main consumer)

I modeled the current into the caps as 
POWER_SUPPLY_PROP_CONSTANT_CHARGE_CURRENT but in retrospect, that may 
not be the right place.  Maybe that should be the "CURRENT_NOW" of the 
battery component?




...


-- 
Mike Looijmans
System Expert

TOPIC Embedded Products B.V.
Materiaalweg 4, 5681 RJ Best
The Netherlands

T: +31 (0) 499 33 69 69
E: mike.looijmans@topic.nl
W: www.topic.nl

Re: [PATCH v3 2/2] power: supply: ltc3350-charger: Add driver

[Nícolas F. R. A. Prado]

On Sun, Apr 14, 2024 at 07:29:56PM +0200, Sebastian Reichel wrote:
> [+cc Nicolas]
> 
> Hello Mike,
> 
> On Fri, Apr 12, 2024 at 08:53:58AM +0200, Mike Looijmans wrote:
> > > please share output of
> > > ./tools/testing/selftests/power_supply/test_power_supply_properties.sh
> > > below the fold with your next submission. It's useful for verifying,
> > > that you got the unit scaling correct for the standard properties :)
> > 
> > Will do. Did a quick run on the driver as it is now, that yields the
> > following output:
> > 
> > (Any thoughts on the "arithmetic syntax error" messages?)
> 
> The script contains some bash specific shell extensions and should
> use /bin/bash instead of /bin/sh in the shebang. Just call it with
> /bin/bash ./tools/testing/... and you should get rid of them :)
> 
> Nicolas, do you want to send a fix for that to Shuah with Reported-by
> from Mike?

It was easy to make it POSIX-compliant, so I sent a series doing that instead:

https://lore.kernel.org/all/20240415-supply-selftest-posix-sh-v1-0-328f008d698d@collabora.com

Thanks,
Nícolas