[PATCH] hwmon: ltc2990: support all measurement modes

* [PATCH] hwmon: ltc2990: support all measurement modes
@ 2016-11-16 13:53 Tom Levens
  2016-11-16 14:45 ` Guenter Roeck
  0 siblings, 1 reply; 2+ messages in thread
From: Tom Levens @ 2016-11-16 13:53 UTC (permalink / raw)
  To: jdelvare, linux; +Cc: tom.levens, linux-hwmon, linux-kernel

Updated ltc2990 driver to support all possible measurement modes that
the chip provides. Mode can be set through a device tree attribute or by
writing to the "mode" sysfs attribute.

Signed-off-by: Tom Levens <tom.levens@cern.ch>
---
 .../devicetree/bindings/hwmon/ltc2990.txt          |   15 +
 Documentation/hwmon/ltc2990                        |   25 ++-
 drivers/hwmon/Kconfig                              |    7 +-
 drivers/hwmon/ltc2990.c                            |  268 +++++++++++++++++---
 4 files changed, 266 insertions(+), 49 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/hwmon/ltc2990.txt

diff --git a/Documentation/devicetree/bindings/hwmon/ltc2990.txt b/Documentation/devicetree/bindings/hwmon/ltc2990.txt
new file mode 100644
index 0000000..0a17e8d
--- /dev/null
+++ b/Documentation/devicetree/bindings/hwmon/ltc2990.txt
@@ -0,0 +1,15 @@
+ltc2990
+
+Required properties:
+- compatible: must be "lltc,ltc2990"
+- reg: I2C slave address
+
+Optional properties:
+- mode: measurement mode (0-7), see Documentation/hwmon/ltc2990 for details
+
+Example:
+ltc2990@4c {
+	compatible = "lltc,ltc2990";
+	mode = <7>;
+	reg = <0x4c>;
+};
diff --git a/Documentation/hwmon/ltc2990 b/Documentation/hwmon/ltc2990
index c25211e..a97df88 100644
--- a/Documentation/hwmon/ltc2990
+++ b/Documentation/hwmon/ltc2990
@@ -8,6 +8,7 @@ Supported chips:
     Datasheet: http://www.linear.com/product/ltc2990
 
 Author: Mike Looijmans <mike.looijmans@topic.nl>
+        Tom Levens <tom.levens@cern.ch>
 
 
 Description
@@ -16,10 +17,8 @@ Description
 LTC2990 is a Quad I2C Voltage, Current and Temperature Monitor.
 The chip's inputs can measure 4 voltages, or two inputs together (1+2 and 3+4)
 can be combined to measure a differential voltage, which is typically used to
-measure current through a series resistor, or a temperature.
-
-This driver currently uses the 2x differential mode only. In order to support
-other modes, the driver will need to be expanded.
+measure current through a series resistor, or a temperature with an external
+diode.
 
 
 Usage Notes
@@ -32,12 +31,20 @@ devices explicitly.
 Sysfs attributes
 ----------------
 
+in0_input     Voltage at Vcc pin in millivolt (range 2.5V to 5V)
+temp1_input   Internal chip temperature in millidegrees Celcius
+mode          Set the measurement mode (range 0 to 7)
+
+A subset of the following attributes are visible, depending on the programmed
+measurement mode.
+
+in[1-4]_input Voltage at V[1-4] pin in millivolt
+temp2_input   External temperature sensor TR1 in millidegrees Celcius
+temp3_input   External temperature sensor TR2 in millidegrees Celcius
+curr1_input   Current in mA across V1-V2 assuming a 1mOhm sense resistor
+curr2_input   Current in mA across V3-V4 assuming a 1mOhm sense resistor
+
 The "curr*_input" measurements actually report the voltage drop across the
 input pins in microvolts. This is equivalent to the current through a 1mOhm
 sense resistor. Divide the reported value by the actual sense resistor value
 in mOhm to get the actual value.
-
-in0_input     Voltage at Vcc pin in millivolt (range 2.5V to 5V)
-temp1_input   Internal chip temperature in millidegrees Celcius
-curr1_input   Current in mA across v1-v2 assuming a 1mOhm sense resistor.
-curr2_input   Current in mA across v3-v4 assuming a 1mOhm sense resistor.
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 45cef3d..f7096ca 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -699,15 +699,12 @@ config SENSORS_LTC2945
 	  be called ltc2945.
 
 config SENSORS_LTC2990
-	tristate "Linear Technology LTC2990 (current monitoring mode only)"
+	tristate "Linear Technology LTC2990"
 	depends on I2C
 	help
 	  If you say yes here you get support for Linear Technology LTC2990
 	  I2C System Monitor. The LTC2990 supports a combination of voltage,
-	  current and temperature monitoring, but in addition to the Vcc supply
-	  voltage and chip temperature, this driver currently only supports
-	  reading two currents by measuring two differential voltages across
-	  series resistors.
+	  current and temperature monitoring.
 
 	  This driver can also be built as a module. If so, the module will
 	  be called ltc2990.
diff --git a/drivers/hwmon/ltc2990.c b/drivers/hwmon/ltc2990.c
index 8f8fe05..b6f910d 100644
--- a/drivers/hwmon/ltc2990.c
+++ b/drivers/hwmon/ltc2990.c
@@ -4,11 +4,10 @@
  * Copyright (C) 2014 Topic Embedded Products
  * Author: Mike Looijmans <mike.looijmans@topic.nl>
  *
- * License: GPLv2
+ * Copyright (C) 2016 European Organization for Nuclear Research (CERN)
+ * Author: Tom Levens <tom.levens@cern.ch>
  *
- * This driver assumes the chip is wired as a dual current monitor, and
- * reports the voltage drop across two series resistors. It also reports
- * the chip's internal temperature and Vcc power supply voltage.
+ * License: GPLv2
  */
 
 #include <linux/err.h>
@@ -17,6 +16,7 @@
 #include <linux/i2c.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <linux/of.h>
 
 #define LTC2990_STATUS	0x00
 #define LTC2990_CONTROL	0x01
@@ -31,8 +31,36 @@
 #define LTC2990_CONTROL_KELVIN		BIT(7)
 #define LTC2990_CONTROL_SINGLE		BIT(6)
 #define LTC2990_CONTROL_MEASURE_ALL	(0x3 << 3)
-#define LTC2990_CONTROL_MODE_CURRENT	0x06
-#define LTC2990_CONTROL_MODE_VOLTAGE	0x07
+#define LTC2990_CONTROL_MODE_DEFAULT	0x06
+#define LTC2990_CONTROL_MODE_MAX	0x07
+
+#define LTC2990_IN0	BIT(0)
+#define LTC2990_IN1	BIT(1)
+#define LTC2990_IN2	BIT(2)
+#define LTC2990_IN3	BIT(3)
+#define LTC2990_IN4	BIT(4)
+#define LTC2990_CURR1	BIT(5)
+#define LTC2990_CURR2	BIT(6)
+#define LTC2990_TEMP1	BIT(7)
+#define LTC2990_TEMP2	BIT(8)
+#define LTC2990_TEMP3	BIT(9)
+
+static const int ltc2990_attrs_ena[] = {
+	LTC2990_IN1 | LTC2990_IN2 | LTC2990_TEMP3,
+	LTC2990_CURR1 | LTC2990_TEMP3,
+	LTC2990_CURR1 | LTC2990_IN3 | LTC2990_IN4,
+	LTC2990_TEMP2 | LTC2990_IN3 | LTC2990_IN4,
+	LTC2990_TEMP2 | LTC2990_CURR2,
+	LTC2990_TEMP2 | LTC2990_TEMP3,
+	LTC2990_CURR1 | LTC2990_CURR2,
+	LTC2990_IN1 | LTC2990_IN2 | LTC2990_IN3 | LTC2990_IN4
+};
+
+struct ltc2990_data {
+	struct i2c_client *i2c;
+	struct mutex update_lock;
+	u32 mode;
+};
 
 /* convert raw register value to sign-extended integer in 16-bit range */
 static int ltc2990_voltage_to_int(int raw)
@@ -44,30 +72,68 @@ static int ltc2990_voltage_to_int(int raw)
 }
 
 /* Return the converted value from the given register in uV or mC */
-static int ltc2990_get_value(struct i2c_client *i2c, u8 reg, int *result)
+static int ltc2990_get_value(struct i2c_client *i2c, int index, int *result)
 {
 	int val;
+	u8 reg;
+
+	switch (index) {
+	case LTC2990_IN0:
+		reg = LTC2990_VCC_MSB;
+		break;
+	case LTC2990_IN1:
+	case LTC2990_CURR1:
+	case LTC2990_TEMP2:
+		reg = LTC2990_V1_MSB;
+		break;
+	case LTC2990_IN2:
+		reg = LTC2990_V2_MSB;
+		break;
+	case LTC2990_IN3:
+	case LTC2990_CURR2:
+	case LTC2990_TEMP3:
+		reg = LTC2990_V3_MSB;
+		break;
+	case LTC2990_IN4:
+		reg = LTC2990_V4_MSB;
+		break;
+	case LTC2990_TEMP1:
+		reg = LTC2990_TINT_MSB;
+		break;
+	default:
+		return -EINVAL;
+	}
 
 	val = i2c_smbus_read_word_swapped(i2c, reg);
 	if (unlikely(val < 0))
 		return val;
 
-	switch (reg) {
-	case LTC2990_TINT_MSB:
-		/* internal temp, 0.0625 degrees/LSB, 13-bit  */
+	switch (index) {
+	case LTC2990_TEMP1:
+	case LTC2990_TEMP2:
+	case LTC2990_TEMP3:
+		/* temp, 0.0625 degrees/LSB, 13-bit  */
 		val = (val & 0x1FFF) << 3;
 		*result = (val * 1000) >> 7;
 		break;
-	case LTC2990_V1_MSB:
-	case LTC2990_V3_MSB:
-		 /* Vx-Vy, 19.42uV/LSB. Depends on mode. */
+	case LTC2990_CURR1:
+	case LTC2990_CURR2:
+		 /* Vx-Vy, 19.42uV/LSB */
 		*result = ltc2990_voltage_to_int(val) * 1942 / (4 * 100);
 		break;
-	case LTC2990_VCC_MSB:
-		/* Vcc, 305.18Î¼V/LSB, 2.5V offset */
+	case LTC2990_IN0:
+		/* Vcc, 305.18uV/LSB, 2.5V offset */
 		*result = (ltc2990_voltage_to_int(val) * 30518 /
 			   (4 * 100 * 1000)) + 2500;
 		break;
+	case LTC2990_IN1:
+	case LTC2990_IN2:
+	case LTC2990_IN3:
+	case LTC2990_IN4:
+		/* Vx: 305.18uV/LSB */
+		*result = (ltc2990_voltage_to_int(val) * 30518 /
+			   (4 * 100 * 1000));
+		break;
 	default:
 		return -EINVAL; /* won't happen, keep compiler happy */
 	}
@@ -75,66 +141,198 @@ static int ltc2990_get_value(struct i2c_client *i2c, u8 reg, int *result)
 	return 0;
 }
 
+
+static int ltc2990_write_control_trigger(struct ltc2990_data *data)
+{
+	int ret;
+
+	/* Setup continuous mode */
+	ret = i2c_smbus_write_byte_data(data->i2c, LTC2990_CONTROL,
+					LTC2990_CONTROL_MEASURE_ALL |
+					data->mode);
+	if (unlikely(ret < 0)) {
+		dev_err(&data->i2c->dev,
+			"Error: Failed to set control mode.\n");
+		return ret;
+	}
+	/* Trigger once to start continuous conversion */
+	ret = i2c_smbus_write_byte_data(data->i2c, LTC2990_TRIGGER, 0x01);
+	if (unlikely(ret < 0)) {
+		dev_err(&data->i2c->dev,
+		"Error: Failed to start acquisition.\n");
+		return ret;
+	}
+
+	return 0;
+}
+
 static ssize_t ltc2990_show_value(struct device *dev,
 				  struct device_attribute *da, char *buf)
 {
 	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
+	struct ltc2990_data *data = dev_get_drvdata(dev);
 	int value;
 	int ret;
 
-	ret = ltc2990_get_value(dev_get_drvdata(dev), attr->index, &value);
+	ret = ltc2990_get_value(data->i2c, attr->index, &value);
 	if (unlikely(ret < 0))
 		return ret;
 
 	return snprintf(buf, PAGE_SIZE, "%d\n", value);
 }
 
+static ssize_t ltc2990_get_mode(struct device *dev,
+				struct device_attribute *da, char *buf)
+{
+	struct ltc2990_data *data = dev_get_drvdata(dev);
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", data->mode);
+}
+
+static const struct attribute_group ltc2990_group;
+
+static ssize_t ltc2990_set_mode(struct device *dev,
+				struct device_attribute *da,
+				const char *buf, size_t count)
+{
+	struct ltc2990_data *data = dev_get_drvdata(dev);
+	int ret;
+	unsigned long mode;
+
+	ret = kstrtoul(buf, 10, &mode);
+	if (unlikely(ret))
+		return ret;
+
+	if (mode > LTC2990_CONTROL_MODE_MAX)
+		return -EINVAL;
+
+	mutex_lock(&data->update_lock);
+
+	data->mode = mode;
+
+	ret = ltc2990_write_control_trigger(data);
+	if (unlikely(ret < 0))
+		goto abort;
+
+	ret = sysfs_update_group(&dev->kobj, &ltc2990_group);
+	if (unlikely(ret < 0))
+		goto abort;
+
+	ret = count;
+
+abort:
+	mutex_unlock(&data->update_lock);
+	return ret;
+}
+
+static umode_t ltc2990_attrs_visible(struct kobject *kobj,
+				     struct attribute *a, int n)
+{
+	struct device *dev = container_of(kobj, struct device, kobj);
+	struct ltc2990_data *data = dev_get_drvdata(dev);
+	struct device_attribute *da =
+			container_of(a, struct device_attribute, attr);
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
+
+	if (ltc2990_attrs_ena[data->mode] & attr->index)
+		return a->mode;
+	else
+		return 0;
+}
+
 static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, ltc2990_show_value, NULL,
-			  LTC2990_TINT_MSB);
+			  LTC2990_TEMP1);
+static SENSOR_DEVICE_ATTR(temp2_input, S_IRUGO, ltc2990_show_value, NULL,
+			  LTC2990_TEMP2);
+static SENSOR_DEVICE_ATTR(temp3_input, S_IRUGO, ltc2990_show_value, NULL,
+			  LTC2990_TEMP3);
 static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, ltc2990_show_value, NULL,
-			  LTC2990_V1_MSB);
+			  LTC2990_CURR1);
 static SENSOR_DEVICE_ATTR(curr2_input, S_IRUGO, ltc2990_show_value, NULL,
-			  LTC2990_V3_MSB);
+			  LTC2990_CURR2);
 static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, ltc2990_show_value, NULL,
-			  LTC2990_VCC_MSB);
+			  LTC2990_IN0);
+static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ltc2990_show_value, NULL,
+			  LTC2990_IN1);
+static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, ltc2990_show_value, NULL,
+			  LTC2990_IN2);
+static SENSOR_DEVICE_ATTR(in3_input, S_IRUGO, ltc2990_show_value, NULL,
+			  LTC2990_IN3);
+static SENSOR_DEVICE_ATTR(in4_input, S_IRUGO, ltc2990_show_value, NULL,
+			  LTC2990_IN4);
+static SENSOR_DEVICE_ATTR(mode, S_IRUGO | S_IWUSR, ltc2990_get_mode,
+			  ltc2990_set_mode, 0);
 
 static struct attribute *ltc2990_attrs[] = {
-	&sensor_dev_attr_temp1_input.dev_attr.attr,
+	&sensor_dev_attr_temp2_input.dev_attr.attr,
+	&sensor_dev_attr_temp3_input.dev_attr.attr,
 	&sensor_dev_attr_curr1_input.dev_attr.attr,
 	&sensor_dev_attr_curr2_input.dev_attr.attr,
+	&sensor_dev_attr_in1_input.dev_attr.attr,
+	&sensor_dev_attr_in2_input.dev_attr.attr,
+	&sensor_dev_attr_in3_input.dev_attr.attr,
+	&sensor_dev_attr_in4_input.dev_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group ltc2990_group = {
+	.attrs = ltc2990_attrs,
+	.is_visible = ltc2990_attrs_visible,
+};
+
+static struct attribute *ltc2990_static_attrs[] = {
+	&sensor_dev_attr_temp1_input.dev_attr.attr,
 	&sensor_dev_attr_in0_input.dev_attr.attr,
+	&sensor_dev_attr_mode.dev_attr.attr,
+	NULL,
+};
+
+static const struct attribute_group ltc2990_static_group = {
+	.attrs = ltc2990_static_attrs
+};
+
+static const struct attribute_group *ltc2990_groups[] = {
+	&ltc2990_group,
+	&ltc2990_static_group,
 	NULL,
 };
-ATTRIBUTE_GROUPS(ltc2990);
 
 static int ltc2990_i2c_probe(struct i2c_client *i2c,
 			     const struct i2c_device_id *id)
 {
 	int ret;
 	struct device *hwmon_dev;
+	struct ltc2990_data *data;
+	struct device_node *of_node = i2c->dev.of_node;
 
 	if (!i2c_check_functionality(i2c->adapter, I2C_FUNC_SMBUS_BYTE_DATA |
 				     I2C_FUNC_SMBUS_WORD_DATA))
 		return -ENODEV;
 
-	/* Setup continuous mode, current monitor */
-	ret = i2c_smbus_write_byte_data(i2c, LTC2990_CONTROL,
-					LTC2990_CONTROL_MEASURE_ALL |
-					LTC2990_CONTROL_MODE_CURRENT);
-	if (ret < 0) {
-		dev_err(&i2c->dev, "Error: Failed to set control mode.\n");
-		return ret;
+	data = devm_kzalloc(&i2c->dev, sizeof(struct ltc2990_data), GFP_KERNEL);
+	if (unlikely(!data))
+		return -ENOMEM;
+	data->i2c = i2c;
+
+	if (!of_node || of_property_read_u32(of_node, "mode", &data->mode))
+		data->mode = LTC2990_CONTROL_MODE_DEFAULT;
+
+	if (data->mode > LTC2990_CONTROL_MODE_MAX) {
+		dev_warn(&data->i2c->dev,
+			"Warning: Mode %d out of range, defaulting to %d.\n",
+			data->mode, LTC2990_CONTROL_MODE_DEFAULT);
+		data->mode = LTC2990_CONTROL_MODE_DEFAULT;
 	}
-	/* Trigger once to start continuous conversion */
-	ret = i2c_smbus_write_byte_data(i2c, LTC2990_TRIGGER, 1);
-	if (ret < 0) {
-		dev_err(&i2c->dev, "Error: Failed to start acquisition.\n");
+
+	ret = ltc2990_write_control_trigger(data);
+	if (unlikely(ret < 0))
 		return ret;
-	}
+
+	mutex_init(&data->update_lock);
 
 	hwmon_dev = devm_hwmon_device_register_with_groups(&i2c->dev,
 							   i2c->name,
-							   i2c,
+							   data,
 							   ltc2990_groups);
 
 	return PTR_ERR_OR_ZERO(hwmon_dev);
-- 
1.7.1

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