[PATCH] hwmon/ltc2990: Support all modes of operation

From: Mike Looijmans
Date: Wed Jun 28 2017 - 10:24:38 EST

The LTC2990 driver so far only supported "current" monitoring. This expands
the driver to support all 8 modes of operation as defined in the mode bits
in the datasheet, thus the device can now be used to monitor up to 4
voltages, 2 currents, or 2 temperature sensors, and some combinations
thereof.

The device mode is configured by using the "mode" value as device name,
e.g. specifying compatible="lltc,ltc2990-6" in the devicetree will set it
to dual-current monitoring mode (6). For backward compatibility, the
default is mode 6.

Signed-off-by: Mike Looijmans <mike.looijmans@xxxxxxxx>
---
drivers/hwmon/Kconfig | 8 +--
drivers/hwmon/ltc2990.c | 172 ++++++++++++++++++++++++++++++++++++++++--------
2 files changed, 148 insertions(+), 32 deletions(-)

diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 5c2d13a..242e22f 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -686,15 +686,13 @@ 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, in addition to the Vcc supply
+ voltage and chip temperature.

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..9c621a1 100644
--- a/drivers/hwmon/ltc2990.c
+++ b/drivers/hwmon/ltc2990.c
@@ -6,9 +6,10 @@
*
* License: GPLv2
*
- * 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.
+ * To configure the driver, pass its desired "mode" (lower 3 bits of control
+ * register) as its device name. Depending on this mode, the chip will report
+ * temperature, current and/or voltage measuments. It always reports the chip's
+ * internal temperature and Vcc power supply voltage.
*/

#include <linux/err.h>
@@ -27,12 +28,18 @@
#define LTC2990_V3_MSB 0x0A
#define LTC2990_V4_MSB 0x0C
#define LTC2990_VCC_MSB 0x0E
+#define LTC2990_REGISTER_MASK 0x0F

#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_CONVERSION_CURRENT 0x00
+#define LTC2990_CONVERSION_TEMPERATURE 0x40
+#define LTC2990_CONVERSION_VOLTAGE 0x80
+#define LTC2990_CONVERSION_VOLTAGE25 0xC0
+#define LTC2990_CONVERSION_MASK 0xC0

/* convert raw register value to sign-extended integer in 16-bit range */
static int ltc2990_voltage_to_int(int raw)
@@ -44,26 +51,30 @@ 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, u8 conv_reg, int *result)
{
int val;

- val = i2c_smbus_read_word_swapped(i2c, reg);
+ val = i2c_smbus_read_word_swapped(i2c, conv_reg & LTC2990_REGISTER_MASK);
if (unlikely(val < 0))
return val;

- switch (reg) {
- case LTC2990_TINT_MSB:
- /* internal temp, 0.0625 degrees/LSB, 13-bit */
+ switch (conv_reg & LTC2990_CONVERSION_MASK) {
+ case LTC2990_CONVERSION_CURRENT:
+ /* Current as differential Vx-Vy, 19.42uV/LSB. */
+ *result = ltc2990_voltage_to_int(val) * 1942 / (4 * 100);
+ break;
+ case LTC2990_CONVERSION_TEMPERATURE:
+ /* Temperature, 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. */
- *result = ltc2990_voltage_to_int(val) * 1942 / (4 * 100);
+ case LTC2990_CONVERSION_VOLTAGE:
+ /* Voltage, 305.18ÎV/LSB */
+ *result = (ltc2990_voltage_to_int(val) * 30518 /
+ (4 * 100 * 1000));
break;
- case LTC2990_VCC_MSB:
+ case LTC2990_CONVERSION_VOLTAGE25:
/* Vcc, 305.18ÎV/LSB, 2.5V offset */
*result = (ltc2990_voltage_to_int(val) * 30518 /
(4 * 100 * 1000)) + 2500;
@@ -89,38 +100,129 @@ static ssize_t ltc2990_show_value(struct device *dev,
return snprintf(buf, PAGE_SIZE, "%d\n", value);
}

+/* Internal temperature and Vcc voltage are always present */
static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO, ltc2990_show_value, NULL,
- LTC2990_TINT_MSB);
+ LTC2990_CONVERSION_TEMPERATURE | LTC2990_TINT_MSB);
+static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, ltc2990_show_value, NULL,
+ LTC2990_CONVERSION_VOLTAGE25 | LTC2990_VCC_MSB);
+/* Current measurement requires 2 inputs per channel */
static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, ltc2990_show_value, NULL,
- LTC2990_V1_MSB);
+ LTC2990_CONVERSION_CURRENT | LTC2990_V1_MSB);
static SENSOR_DEVICE_ATTR(curr2_input, S_IRUGO, ltc2990_show_value, NULL,
- LTC2990_V3_MSB);
-static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, ltc2990_show_value, NULL,
- LTC2990_VCC_MSB);
+ LTC2990_CONVERSION_CURRENT | LTC2990_V3_MSB);
+/* Voltage measurement requires 1 input per channel */
+static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ltc2990_show_value, NULL,
+ LTC2990_CONVERSION_VOLTAGE | LTC2990_V1_MSB);
+static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, ltc2990_show_value, NULL,
+ LTC2990_CONVERSION_VOLTAGE | LTC2990_V2_MSB);
+static SENSOR_DEVICE_ATTR(in3_input, S_IRUGO, ltc2990_show_value, NULL,
+ LTC2990_CONVERSION_VOLTAGE | LTC2990_V3_MSB);
+static SENSOR_DEVICE_ATTR(in4_input, S_IRUGO, ltc2990_show_value, NULL,
+ LTC2990_CONVERSION_VOLTAGE | LTC2990_V4_MSB);
+/* Temperature measurement requires 2 inputs per channel */
+static SENSOR_DEVICE_ATTR(temp2_input, S_IRUGO, ltc2990_show_value, NULL,
+ LTC2990_CONVERSION_TEMPERATURE | LTC2990_V1_MSB);
+static SENSOR_DEVICE_ATTR(temp3_input, S_IRUGO, ltc2990_show_value, NULL,
+ LTC2990_CONVERSION_TEMPERATURE | LTC2990_V3_MSB);

-static struct attribute *ltc2990_attrs[] = {
+
+/* Common attributes regardless of mode */
+static struct attribute *ltc2990_common_attrs[] = {
&sensor_dev_attr_temp1_input.dev_attr.attr,
+ &sensor_dev_attr_in0_input.dev_attr.attr,
+ NULL,
+};
+static const struct attribute_group ltc2990_common_group = {
+ .attrs = ltc2990_common_attrs,
+};
+
+/* Attribute to mode mapping, as per the CONTROL register bits [2:0] */
+
+/* 000 = V1 V2 TR2 */
+static struct attribute *ltc2990_000_attrs[] = {
+ &sensor_dev_attr_in1_input.dev_attr.attr,
+ &sensor_dev_attr_in2_input.dev_attr.attr,
+ &sensor_dev_attr_temp3_input.dev_attr.attr,
+ NULL,
+};
+/* 001 = V1-V2 TR2 */
+static struct attribute *ltc2990_001_attrs[] = {
+ &sensor_dev_attr_curr1_input.dev_attr.attr,
+ &sensor_dev_attr_temp3_input.dev_attr.attr,
+ NULL,
+};
+/* 010 = V1-V2 V3 V4 */
+static struct attribute *ltc2990_010_attrs[] = {
&sensor_dev_attr_curr1_input.dev_attr.attr,
+ &sensor_dev_attr_in3_input.dev_attr.attr,
+ &sensor_dev_attr_in4_input.dev_attr.attr,
+ NULL,
+};
+/* 011 = TR1 V3 V4 */
+static struct attribute *ltc2990_011_attrs[] = {
+ &sensor_dev_attr_temp2_input.dev_attr.attr,
+ &sensor_dev_attr_in3_input.dev_attr.attr,
+ &sensor_dev_attr_in4_input.dev_attr.attr,
+ NULL,
+};
+/* 100 = TR1 V3-V4 */
+static struct attribute *ltc2990_100_attrs[] = {
+ &sensor_dev_attr_temp2_input.dev_attr.attr,
&sensor_dev_attr_curr2_input.dev_attr.attr,
- &sensor_dev_attr_in0_input.dev_attr.attr,
NULL,
};
-ATTRIBUTE_GROUPS(ltc2990);
+/* 101 = TR1 TR2 */
+static struct attribute *ltc2990_101_attrs[] = {
+ &sensor_dev_attr_temp2_input.dev_attr.attr,
+ &sensor_dev_attr_temp3_input.dev_attr.attr,
+ NULL,
+};
+/* 110 = V1-V2 V3-V4 */
+static struct attribute *ltc2990_110_attrs[] = {
+ &sensor_dev_attr_curr1_input.dev_attr.attr,
+ &sensor_dev_attr_curr2_input.dev_attr.attr,
+ NULL,
+};
+/* 111 = V1 V2 V3 V4 */
+static struct attribute *ltc2990_111_attrs[] = {
+ &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,
+};
+/* Decoder array for mode index */
+static struct attribute **ltc2990_attr_list[] = {
+ ltc2990_000_attrs,
+ ltc2990_001_attrs,
+ ltc2990_010_attrs,
+ ltc2990_011_attrs,
+ ltc2990_100_attrs,
+ ltc2990_101_attrs,
+ ltc2990_110_attrs,
+ ltc2990_111_attrs,
+};
+
+struct ltc2990_driver_data {
+ struct attribute_group ltc2990_extra_group;
+ const struct attribute_group *ltc2990_groups[3];
+};

static int ltc2990_i2c_probe(struct i2c_client *i2c,
const struct i2c_device_id *id)
{
int ret;
struct device *hwmon_dev;
+ struct ltc2990_driver_data *data;

if (!i2c_check_functionality(i2c->adapter, I2C_FUNC_SMBUS_BYTE_DATA |
I2C_FUNC_SMBUS_WORD_DATA))
return -ENODEV;

- /* Setup continuous mode, current monitor */
+ /* Setup continuous monitoring mode */
ret = i2c_smbus_write_byte_data(i2c, LTC2990_CONTROL,
LTC2990_CONTROL_MEASURE_ALL |
- LTC2990_CONTROL_MODE_CURRENT);
+ id->driver_data);
if (ret < 0) {
dev_err(&i2c->dev, "Error: Failed to set control mode.\n");
return ret;
@@ -132,16 +234,32 @@ static int ltc2990_i2c_probe(struct i2c_client *i2c,
return ret;
}

+ /* Define attributes based on chip mode */
+ data = devm_kzalloc(&i2c->dev, sizeof(*data), GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+ data->ltc2990_extra_group.attrs = ltc2990_attr_list[id->driver_data];
+ data->ltc2990_groups[0] = &ltc2990_common_group;
+ data->ltc2990_groups[1] = &data->ltc2990_extra_group;
+
hwmon_dev = devm_hwmon_device_register_with_groups(&i2c->dev,
i2c->name,
i2c,
- ltc2990_groups);
+ data->ltc2990_groups);

return PTR_ERR_OR_ZERO(hwmon_dev);
}

static const struct i2c_device_id ltc2990_i2c_id[] = {
- { "ltc2990", 0 },
+ { "ltc2990", LTC2990_CONTROL_MODE_DEFAULT},
+ { "ltc29900", 0},
+ { "ltc29901", 1},
+ { "ltc29902", 2},
+ { "ltc29903", 3},
+ { "ltc29904", 4},
+ { "ltc29905", 5},
+ { "ltc29906", 6},
+ { "ltc29907", 7},
{}
};
MODULE_DEVICE_TABLE(i2c, ltc2990_i2c_id);
--
1.9.1