[PATCH v4 0/2] power: supply: ltc2941-battery-gauge: Support LTC2942

[PATCH v4 0/2] power: supply: ltc2941-battery-gauge: Support LTC2942

[Ladislav Michl]

This is 4th version of patch.
Changelog:
- v2: reworked voltage computing to not overflow and keep presision
- v3: update devicetree binding documentation
- v4: add ltc2942 devicetree compatible
 
LTC2942 is pin compatible with LTC2941 providing few more registers
holding information about battery voltage and temperature. It can
be runtime detected using bit A7 in the Status register.

PATCH 1/2 defines LTC2942 registers with no functional changes
while 2/2 does actually the job.

I'm not sure, whenever splitting support into two patches makes
sense, but it just makes reviewing easier. I'd happily
squash patches together.

Comments welcome,
	ladis

[PATCH v4 1/2] power: supply: ltc2941-battery-gauge: Define LTC2942 registers

[Ladislav Michl]

In order to support LTC2942 which has temperature registers
at different offsets than LTC2943 use following register naming
scheme (prefixes):
- LTC294X_ common registers
- LTC2942_ chips specific registers
- LTC2943_ specific registers
There are no functional changes.

Signed-off-by: Ladislav Michl <ladis-6z/3iImG2C8G8FEW9MqTrA@public.gmane.org>
---
 Changes:
 - v2: None
 - v3: Extend commit message
 - v4: None

 drivers/power/supply/ltc2941-battery-gauge.c | 27 +++++++++++++--------------
 1 file changed, 13 insertions(+), 14 deletions(-)

diff --git a/drivers/power/supply/ltc2941-battery-gauge.c b/drivers/power/supply/ltc2941-battery-gauge.c
index 7efb908f4451..0a1b69bbca7f 100644
--- a/drivers/power/supply/ltc2941-battery-gauge.c
+++ b/drivers/power/supply/ltc2941-battery-gauge.c
@@ -34,16 +34,14 @@ enum ltc294x_reg {
 	LTC294X_REG_CONTROL		= 0x01,
 	LTC294X_REG_ACC_CHARGE_MSB	= 0x02,
 	LTC294X_REG_ACC_CHARGE_LSB	= 0x03,
-	LTC294X_REG_THRESH_HIGH_MSB	= 0x04,
-	LTC294X_REG_THRESH_HIGH_LSB	= 0x05,
-	LTC294X_REG_THRESH_LOW_MSB	= 0x06,
-	LTC294X_REG_THRESH_LOW_LSB	= 0x07,
-	LTC294X_REG_VOLTAGE_MSB	= 0x08,
-	LTC294X_REG_VOLTAGE_LSB	= 0x09,
-	LTC294X_REG_CURRENT_MSB	= 0x0E,
-	LTC294X_REG_CURRENT_LSB	= 0x0F,
-	LTC294X_REG_TEMPERATURE_MSB	= 0x14,
-	LTC294X_REG_TEMPERATURE_LSB	= 0x15,
+	LTC294X_REG_VOLTAGE_MSB		= 0x08,
+	LTC294X_REG_VOLTAGE_LSB		= 0x09,
+	LTC2942_REG_TEMPERATURE_MSB	= 0x0C,
+	LTC2942_REG_TEMPERATURE_LSB	= 0x0D,
+	LTC2943_REG_CURRENT_MSB		= 0x0E,
+	LTC2943_REG_CURRENT_LSB		= 0x0F,
+	LTC2943_REG_TEMPERATURE_MSB	= 0x14,
+	LTC2943_REG_TEMPERATURE_LSB	= 0x15,
 };
 
 #define LTC2943_REG_CONTROL_MODE_MASK (BIT(7) | BIT(6))
@@ -55,6 +53,7 @@ enum ltc294x_reg {
 #define LTC294X_REG_CONTROL_ALCC_CONFIG_DISABLED	0
 
 #define LTC2941_NUM_REGS	0x08
+#define LTC2942_NUM_REGS	0x10
 #define LTC2943_NUM_REGS	0x18
 
 struct ltc294x_info {
@@ -263,7 +262,7 @@ static int ltc294x_get_current(const struct ltc294x_info *info, int *val)
 	s32 value;
 
 	ret = ltc294x_read_regs(info->client,
-		LTC294X_REG_CURRENT_MSB, &datar[0], 2);
+		LTC2943_REG_CURRENT_MSB, &datar[0], 2);
 	value = (datar[0] << 8) | datar[1];
 	value -= 0x7FFF;
 	/* Value is in range -32k..+32k, r_sense is usually 10..50 mOhm,
@@ -280,7 +279,7 @@ static int ltc294x_get_temperature(const struct ltc294x_info *info, int *val)
 	u32 value;
 
 	ret = ltc294x_read_regs(info->client,
-		LTC294X_REG_TEMPERATURE_MSB, &datar[0], 2);
+		LTC2943_REG_TEMPERATURE_MSB, &datar[0], 2);
 	value = (datar[0] << 8) | datar[1];
 	/* Full-scale is 510 Kelvin, convert to centidegrees  */
 	*val = (((51000 * value) / 0xFFFF) - 27215);
@@ -424,10 +423,10 @@ static int ltc294x_i2c_probe(struct i2c_client *client,
 	info->client = client;
 	info->supply_desc.type = POWER_SUPPLY_TYPE_BATTERY;
 	info->supply_desc.properties = ltc294x_properties;
-	if (info->num_regs >= LTC294X_REG_TEMPERATURE_LSB)
+	if (info->num_regs >= LTC2943_REG_TEMPERATURE_LSB)
 		info->supply_desc.num_properties =
 			ARRAY_SIZE(ltc294x_properties);
-	else if (info->num_regs >= LTC294X_REG_CURRENT_LSB)
+	else if (info->num_regs >= LTC2943_REG_CURRENT_LSB)
 		info->supply_desc.num_properties =
 			ARRAY_SIZE(ltc294x_properties) - 1;
 	else if (info->num_regs >= LTC294X_REG_VOLTAGE_LSB)
-- 
2.11.0

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[PATCH v4 2/2] power: supply: ltc2941-battery-gauge: Add support for LTC2942

[Ladislav Michl]

LTC2942 is pin compatible with LTC2941 providing additional
informations about battery voltage and temperature. It can
be runtime detected using bit A7 in the Status register.

Signed-off-by: Ladislav Michl <ladis-6z/3iImG2C8G8FEW9MqTrA@public.gmane.org>
---
 Changes:
 - v2: reworked voltage computing to not overflow and keep presision
 - v3: update devicetree binding documentation
 - v4: add ltc2942 devicetree compatible

 .../devicetree/bindings/power/supply/ltc2941.txt   | 15 ++--
 drivers/power/supply/ltc2941-battery-gauge.c       | 85 +++++++++++++++++-----
 2 files changed, 74 insertions(+), 26 deletions(-)

diff --git a/Documentation/devicetree/bindings/power/supply/ltc2941.txt b/Documentation/devicetree/bindings/power/supply/ltc2941.txt
index a9d7aa60558b..8ec10366295d 100644
--- a/Documentation/devicetree/bindings/power/supply/ltc2941.txt
+++ b/Documentation/devicetree/bindings/power/supply/ltc2941.txt
@@ -1,13 +1,14 @@
-binding for LTC2941 and LTC2943 battery gauges
+binding for LTC2941, LTC2942 and LTC2943 battery gauges
 
-Both the LTC2941 and LTC2943 measure battery capacity.
-The LTC2943 is compatible with the LTC2941, it adds voltage and
-temperature monitoring, and uses a slightly different conversion
-formula for the charge counter.
+All chips measure battery capacity.
+The LTC2942 is pin compatible with the LTC2941, it adds voltage and
+temperature monitoring, and is runtime detected. LTC2943 is software
+compatible, uses a slightly different conversion formula for the
+charge counter and adds voltage, current and temperature monitoring.
 
 Required properties:
-- compatible: Should contain "lltc,ltc2941" or "lltc,ltc2943" which also
-    indicates the type of I2C chip attached.
+- compatible: Should contain "lltc,ltc2941", "lltc,ltc2942" or "lltc,ltc2943"
+    which also indicates the type of I2C chip attached.
 - reg: The 7-bit I2C address.
 - lltc,resistor-sense: The sense resistor value in milli-ohms. Can be a 32-bit
     negative value when the battery has been connected to the wrong end of the
diff --git a/drivers/power/supply/ltc2941-battery-gauge.c b/drivers/power/supply/ltc2941-battery-gauge.c
index 0a1b69bbca7f..c787c257451e 100644
--- a/drivers/power/supply/ltc2941-battery-gauge.c
+++ b/drivers/power/supply/ltc2941-battery-gauge.c
@@ -44,8 +44,10 @@ enum ltc294x_reg {
 	LTC2943_REG_TEMPERATURE_LSB	= 0x15,
 };
 
-#define LTC2943_REG_CONTROL_MODE_MASK (BIT(7) | BIT(6))
-#define LTC2943_REG_CONTROL_MODE_SCAN BIT(7)
+#define LTC2941_REG_STATUS_CHIP_ID	BIT(7)
+
+#define LTC2942_REG_CONTROL_MODE_SCAN	(BIT(7) | BIT(6))
+#define LTC2943_REG_CONTROL_MODE_SCAN	BIT(7)
 #define LTC294X_REG_CONTROL_PRESCALER_MASK	(BIT(5) | BIT(4) | BIT(3))
 #define LTC294X_REG_CONTROL_SHUTDOWN_MASK	(BIT(0))
 #define LTC294X_REG_CONTROL_PRESCALER_SET(x) \
@@ -144,9 +146,15 @@ static int ltc294x_reset(const struct ltc294x_info *info, int prescaler_exp)
 
 	control = LTC294X_REG_CONTROL_PRESCALER_SET(prescaler_exp) |
 				LTC294X_REG_CONTROL_ALCC_CONFIG_DISABLED;
-	/* Put the 2943 into "monitor" mode, so it measures every 10 sec */
-	if (info->num_regs == LTC2943_NUM_REGS)
+	/* Put device into "monitor" mode */
+	switch (info->num_regs) {
+	case LTC2942_NUM_REGS:	/* 2942 measures every 2 sec */
+		control |= LTC2942_REG_CONTROL_MODE_SCAN;
+		break;
+	case LTC2943_NUM_REGS:	/* 2943 measures every 10 sec */
 		control |= LTC2943_REG_CONTROL_MODE_SCAN;
+		break;
+	}
 
 	if (value != control) {
 		ret = ltc294x_write_regs(info->client,
@@ -251,7 +259,16 @@ static int ltc294x_get_voltage(const struct ltc294x_info *info, int *val)
 	ret = ltc294x_read_regs(info->client,
 		LTC294X_REG_VOLTAGE_MSB, &datar[0], 2);
 	value = (datar[0] << 8) | datar[1];
-	*val = ((value * 23600) / 0xFFFF) * 1000; /* in uV */
+	if (info->num_regs == LTC2943_NUM_REGS) {
+		value *= 23600 * 2;
+		value /= 0xFFFF;
+		value *= 1000 / 2;
+	} else {
+		value *= 6000 * 10;
+		value /= 0xFFFF;
+		value *= 1000 / 10;
+	}
+	*val = value;
 	return ret;
 }
 
@@ -274,15 +291,22 @@ static int ltc294x_get_current(const struct ltc294x_info *info, int *val)
 
 static int ltc294x_get_temperature(const struct ltc294x_info *info, int *val)
 {
+	enum ltc294x_reg reg;
 	int ret;
 	u8 datar[2];
 	u32 value;
 
-	ret = ltc294x_read_regs(info->client,
-		LTC2943_REG_TEMPERATURE_MSB, &datar[0], 2);
-	value = (datar[0] << 8) | datar[1];
-	/* Full-scale is 510 Kelvin, convert to centidegrees  */
-	*val = (((51000 * value) / 0xFFFF) - 27215);
+	if (info->num_regs == LTC2943_NUM_REGS) {
+		reg = LTC2943_REG_TEMPERATURE_MSB;
+		value = 51000;	/* Full-scale is 510 Kelvin */
+	} else {
+		reg = LTC2942_REG_TEMPERATURE_MSB;
+		value = 60000;	/* Full-scale is 600 Kelvin */
+	}
+	ret = ltc294x_read_regs(info->client, reg, &datar[0], 2);
+	value *= (datar[0] << 8) | datar[1];
+	/* Convert to centidegrees  */
+	*val = value / 0xFFFF - 27215;
 	return ret;
 }
 
@@ -356,8 +380,8 @@ static enum power_supply_property ltc294x_properties[] = {
 	POWER_SUPPLY_PROP_CHARGE_COUNTER,
 	POWER_SUPPLY_PROP_CHARGE_NOW,
 	POWER_SUPPLY_PROP_VOLTAGE_NOW,
-	POWER_SUPPLY_PROP_CURRENT_NOW,
 	POWER_SUPPLY_PROP_TEMP,
+	POWER_SUPPLY_PROP_CURRENT_NOW,
 };
 
 static int ltc294x_i2c_remove(struct i2c_client *client)
@@ -374,10 +398,11 @@ static int ltc294x_i2c_probe(struct i2c_client *client,
 {
 	struct power_supply_config psy_cfg = {};
 	struct ltc294x_info *info;
+	struct device_node *np;
 	int ret;
 	u32 prescaler_exp;
 	s32 r_sense;
-	struct device_node *np;
+	u8 status;
 
 	info = devm_kzalloc(&client->dev, sizeof(*info), GFP_KERNEL);
 	if (info == NULL)
@@ -420,21 +445,38 @@ static int ltc294x_i2c_probe(struct i2c_client *client,
 				(128 / (1 << prescaler_exp));
 	}
 
+	/* Read status register to check for LTC2942 */
+	if (info->num_regs != LTC2943_NUM_REGS) {
+		ret = ltc294x_read_regs(client, LTC294X_REG_STATUS, &status, 1);
+		if (ret < 0) {
+			dev_err(&client->dev,
+				"Could not read status register\n");
+			return ret;
+		}
+		if (status & LTC2941_REG_STATUS_CHIP_ID)
+			info->num_regs = LTC2941_NUM_REGS;
+		else
+			info->num_regs = LTC2942_NUM_REGS;
+	}
+
 	info->client = client;
 	info->supply_desc.type = POWER_SUPPLY_TYPE_BATTERY;
 	info->supply_desc.properties = ltc294x_properties;
-	if (info->num_regs >= LTC2943_REG_TEMPERATURE_LSB)
+	switch (info->num_regs) {
+	case LTC2943_NUM_REGS:
 		info->supply_desc.num_properties =
 			ARRAY_SIZE(ltc294x_properties);
-	else if (info->num_regs >= LTC2943_REG_CURRENT_LSB)
+		break;
+	case LTC2942_NUM_REGS:
 		info->supply_desc.num_properties =
 			ARRAY_SIZE(ltc294x_properties) - 1;
-	else if (info->num_regs >= LTC294X_REG_VOLTAGE_LSB)
-		info->supply_desc.num_properties =
-			ARRAY_SIZE(ltc294x_properties) - 2;
-	else
+		break;
+	case LTC2941_NUM_REGS:
+	default:
 		info->supply_desc.num_properties =
 			ARRAY_SIZE(ltc294x_properties) - 3;
+		break;
+	}
 	info->supply_desc.get_property = ltc294x_get_property;
 	info->supply_desc.set_property = ltc294x_set_property;
 	info->supply_desc.property_is_writeable = ltc294x_property_is_writeable;
@@ -492,6 +534,7 @@ static SIMPLE_DEV_PM_OPS(ltc294x_pm_ops, ltc294x_suspend, ltc294x_resume);
 
 static const struct i2c_device_id ltc294x_i2c_id[] = {
 	{"ltc2941", LTC2941_NUM_REGS},
+	{"ltc2942", LTC2942_NUM_REGS},
 	{"ltc2943", LTC2943_NUM_REGS},
 	{ },
 };
@@ -503,6 +546,10 @@ static const struct of_device_id ltc294x_i2c_of_match[] = {
 		.data = (void *)LTC2941_NUM_REGS
 	},
 	{
+		.compatible = "lltc,ltc2942",
+		.data = (void *)LTC2942_NUM_REGS
+	},
+	{
 		.compatible = "lltc,ltc2943",
 		.data = (void *)LTC2943_NUM_REGS
 	},
@@ -524,5 +571,5 @@ module_i2c_driver(ltc294x_driver);
 
 MODULE_AUTHOR("Auryn Verwegen, Topic Embedded Systems");
 MODULE_AUTHOR("Mike Looijmans, Topic Embedded Products");
-MODULE_DESCRIPTION("LTC2941/LTC2943 Battery Gas Gauge IC driver");
+MODULE_DESCRIPTION("LTC2941/LTC2942/LTC2943 Battery Gas Gauge IC driver");
 MODULE_LICENSE("GPL");
-- 
2.11.0

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Re: [PATCH v4 2/2] power: supply: ltc2941-battery-gauge: Add support for LTC2942

[Rob Herring]

On Tue, Jul 11, 2017 at 03:00:20PM +0200, Ladislav Michl wrote:
> LTC2942 is pin compatible with LTC2941 providing additional
> informations about battery voltage and temperature. It can
> be runtime detected using bit A7 in the Status register.
> 
> Signed-off-by: Ladislav Michl <ladis@linux-mips.org>
> ---
>  Changes:
>  - v2: reworked voltage computing to not overflow and keep presision
>  - v3: update devicetree binding documentation
>  - v4: add ltc2942 devicetree compatible
> 
>  .../devicetree/bindings/power/supply/ltc2941.txt   | 15 ++--

Acked-by: Rob Herring <robh@kernel.org>

>  drivers/power/supply/ltc2941-battery-gauge.c       | 85 +++++++++++++++++-----
>  2 files changed, 74 insertions(+), 26 deletions(-)