hwmon: Driver for Linear Technologies LTC2945

LTC2945 is a system monitor that measures current, voltage, and power.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>

1 files changed, 519 insertions, 0 deletions

diff --git a/drivers/hwmon/ltc2945.c b/drivers/hwmon/ltc2945.c
new file mode 100644
index 000000000000..c104cc32989d
--- /dev/null
+++ b/drivers/hwmon/ltc2945.c
@@ -0,0 +1,519 @@
+/*
+ * Driver for Linear Technology LTC2945 I2C Power Monitor
+ *
+ * Copyright (c) 2014 Guenter Roeck
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/jiffies.h>
+#include <linux/regmap.h>
+
+/* chip registers */
+#define LTC2945_CONTROL			0x00
+#define LTC2945_ALERT			0x01
+#define LTC2945_STATUS			0x02
+#define LTC2945_FAULT			0x03
+#define LTC2945_POWER_H			0x05
+#define LTC2945_MAX_POWER_H		0x08
+#define LTC2945_MIN_POWER_H		0x0b
+#define LTC2945_MAX_POWER_THRES_H	0x0e
+#define LTC2945_MIN_POWER_THRES_H	0x11
+#define LTC2945_SENSE_H			0x14
+#define LTC2945_MAX_SENSE_H		0x16
+#define LTC2945_MIN_SENSE_H		0x18
+#define LTC2945_MAX_SENSE_THRES_H	0x1a
+#define LTC2945_MIN_SENSE_THRES_H	0x1c
+#define LTC2945_VIN_H			0x1e
+#define LTC2945_MAX_VIN_H		0x20
+#define LTC2945_MIN_VIN_H		0x22
+#define LTC2945_MAX_VIN_THRES_H		0x24
+#define LTC2945_MIN_VIN_THRES_H		0x26
+#define LTC2945_ADIN_H			0x28
+#define LTC2945_MAX_ADIN_H		0x2a
+#define LTC2945_MIN_ADIN_H		0x2c
+#define LTC2945_MAX_ADIN_THRES_H	0x2e
+#define LTC2945_MIN_ADIN_THRES_H	0x30
+#define LTC2945_MIN_ADIN_THRES_L	0x31
+
+/* Fault register bits */
+
+#define FAULT_ADIN_UV		(1 << 0)
+#define FAULT_ADIN_OV		(1 << 1)
+#define FAULT_VIN_UV		(1 << 2)
+#define FAULT_VIN_OV		(1 << 3)
+#define FAULT_SENSE_UV		(1 << 4)
+#define FAULT_SENSE_OV		(1 << 5)
+#define FAULT_POWER_UV		(1 << 6)
+#define FAULT_POWER_OV		(1 << 7)
+
+/* Control register bits */
+
+#define CONTROL_MULT_SELECT	(1 << 0)
+#define CONTROL_TEST_MODE	(1 << 4)
+
+static inline bool is_power_reg(u8 reg)
+{
+	return reg < LTC2945_SENSE_H;
+}
+
+/* Return the value from the given register in uW, mV, or mA */
+static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
+{
+	struct regmap *regmap = dev_get_drvdata(dev);
+	unsigned int control;
+	u8 buf[3];
+	long long val;
+	int ret;
+
+	ret = regmap_bulk_read(regmap, reg, buf,
+			       is_power_reg(reg) ? 3 : 2);
+	if (ret < 0)
+		return ret;
+
+	if (is_power_reg(reg)) {
+		/* power */
+		val = (buf[0] << 16) + (buf[1] << 8) + buf[2];
+	} else {
+		/* current, voltage */
+		val = (buf[0] << 4) + (buf[1] >> 4);
+	}
+
+	switch (reg) {
+	case LTC2945_POWER_H:
+	case LTC2945_MAX_POWER_H:
+	case LTC2945_MIN_POWER_H:
+	case LTC2945_MAX_POWER_THRES_H:
+	case LTC2945_MIN_POWER_THRES_H:
+		/*
+		 * Convert to uW by assuming current is measured with
+		 * an 1mOhm sense resistor, similar to current
+		 * measurements.
+		 * Control register bit 0 selects if voltage at SENSE+/VDD
+		 * or voltage at ADIN is used to measure power.
+		 */
+		ret = regmap_read(regmap, LTC2945_CONTROL, &control);
+		if (ret < 0)
+			return ret;
+		if (control & CONTROL_MULT_SELECT) {
+			/* 25 mV * 25 uV = 0.625 uV resolution. */
+			val *= 625LL;
+		} else {
+			/* 0.5 mV * 25 uV = 0.0125 uV resolution. */
+			val = (val * 25LL) >> 1;
+		}
+		break;
+	case LTC2945_VIN_H:
+	case LTC2945_MAX_VIN_H:
+	case LTC2945_MIN_VIN_H:
+	case LTC2945_MAX_VIN_THRES_H:
+	case LTC2945_MIN_VIN_THRES_H:
+		/* 25 mV resolution. Convert to mV. */
+		val *= 25;
+		break;
+	case LTC2945_ADIN_H:
+	case LTC2945_MAX_ADIN_H:
+	case LTC2945_MIN_ADIN_THRES_H:
+	case LTC2945_MAX_ADIN_THRES_H:
+	case LTC2945_MIN_ADIN_H:
+		/* 0.5mV resolution. Convert to mV. */
+		val = val >> 1;
+		break;
+	case LTC2945_SENSE_H:
+	case LTC2945_MAX_SENSE_H:
+	case LTC2945_MIN_SENSE_H:
+	case LTC2945_MAX_SENSE_THRES_H:
+	case LTC2945_MIN_SENSE_THRES_H:
+		/*
+		 * 25 uV resolution. Convert to current as measured with
+		 * an 1 mOhm sense resistor, in mA. If a different sense
+		 * resistor is installed, calculate the actual current by
+		 * dividing the reported current by the sense resistor value
+		 * in mOhm.
+		 */
+		val *= 25;
+		break;
+	default:
+		return -EINVAL;
+	}
+	return val;
+}
+
+static int ltc2945_val_to_reg(struct device *dev, u8 reg,
+			      unsigned long val)
+{
+	struct regmap *regmap = dev_get_drvdata(dev);
+	unsigned int control;
+	int ret;
+
+	switch (reg) {
+	case LTC2945_POWER_H:
+	case LTC2945_MAX_POWER_H:
+	case LTC2945_MIN_POWER_H:
+	case LTC2945_MAX_POWER_THRES_H:
+	case LTC2945_MIN_POWER_THRES_H:
+		/*
+		 * Convert to register value by assuming current is measured
+		 * with an 1mOhm sense resistor, similar to current
+		 * measurements.
+		 * Control register bit 0 selects if voltage at SENSE+/VDD
+		 * or voltage at ADIN is used to measure power, which in turn
+		 * determines register calculations.
+		 */
+		ret = regmap_read(regmap, LTC2945_CONTROL, &control);
+		if (ret < 0)
+			return ret;
+		if (control & CONTROL_MULT_SELECT) {
+			/* 25 mV * 25 uV = 0.625 uV resolution. */
+			val = DIV_ROUND_CLOSEST(val, 625);
+		} else {
+			/*
+			 * 0.5 mV * 25 uV = 0.0125 uV resolution.
+			 * Divide first to avoid overflow;
+			 * accept loss of accuracy.
+			 */
+			val = DIV_ROUND_CLOSEST(val, 25) * 2;
+		}
+		break;
+	case LTC2945_VIN_H:
+	case LTC2945_MAX_VIN_H:
+	case LTC2945_MIN_VIN_H:
+	case LTC2945_MAX_VIN_THRES_H:
+	case LTC2945_MIN_VIN_THRES_H:
+		/* 25 mV resolution. */
+		val /= 25;
+		break;
+	case LTC2945_ADIN_H:
+	case LTC2945_MAX_ADIN_H:
+	case LTC2945_MIN_ADIN_THRES_H:
+	case LTC2945_MAX_ADIN_THRES_H:
+	case LTC2945_MIN_ADIN_H:
+		/* 0.5mV resolution. */
+		val *= 2;
+		break;
+	case LTC2945_SENSE_H:
+	case LTC2945_MAX_SENSE_H:
+	case LTC2945_MIN_SENSE_H:
+	case LTC2945_MAX_SENSE_THRES_H:
+	case LTC2945_MIN_SENSE_THRES_H:
+		/*
+		 * 25 uV resolution. Convert to current as measured with
+		 * an 1 mOhm sense resistor, in mA. If a different sense
+		 * resistor is installed, calculate the actual current by
+		 * dividing the reported current by the sense resistor value
+		 * in mOhm.
+		 */
+		val = DIV_ROUND_CLOSEST(val, 25);
+		break;
+	default:
+		return -EINVAL;
+	}
+	return val;
+}
+
+static ssize_t ltc2945_show_value(struct device *dev,
+				  struct device_attribute *da, char *buf)
+{
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
+	long long value;
+
+	value = ltc2945_reg_to_val(dev, attr->index);
+	if (value < 0)
+		return value;
+	return snprintf(buf, PAGE_SIZE, "%lld\n", value);
+}
+
+static ssize_t ltc2945_set_value(struct device *dev,
+				     struct device_attribute *da,
+				     const char *buf, size_t count)
+{
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
+	struct regmap *regmap = dev_get_drvdata(dev);
+	u8 reg = attr->index;
+	unsigned long val;
+	u8 regbuf[3];
+	int num_regs;
+	int regval;
+	int ret;
+
+	ret = kstrtoul(buf, 10, &val);
+	if (ret)
+		return ret;
+
+	/* convert to register value, then clamp and write result */
+	regval = ltc2945_val_to_reg(dev, reg, val);
+	if (is_power_reg(reg)) {
+		regval = clamp_val(regval, 0, 0xffffff);
+		regbuf[0] = regval >> 16;
+		regbuf[1] = (regval >> 8) & 0xff;
+		regbuf[2] = regval;
+		num_regs = 3;
+	} else {
+		regval = clamp_val(regval, 0, 0xfff) << 4;
+		regbuf[0] = regval >> 8;
+		regbuf[1] = regval & 0xff;
+		num_regs = 2;
+	}
+	ret = regmap_bulk_write(regmap, reg, regbuf, num_regs);
+	return ret < 0 ? ret : count;
+}
+
+static ssize_t ltc2945_reset_history(struct device *dev,
+				     struct device_attribute *da,
+				     const char *buf, size_t count)
+{
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
+	struct regmap *regmap = dev_get_drvdata(dev);
+	u8 reg = attr->index;
+	int num_regs = is_power_reg(reg) ? 3 : 2;
+	u8 buf_min[3] = { 0xff, 0xff, 0xff };
+	u8 buf_max[3] = { 0, 0, 0 };
+	unsigned long val;
+	int ret;
+
+	ret = kstrtoul(buf, 10, &val);
+	if (ret)
+		return ret;
+	if (val != 1)
+		return -EINVAL;
+
+	ret = regmap_update_bits(regmap, LTC2945_CONTROL, CONTROL_TEST_MODE,
+				 CONTROL_TEST_MODE);
+
+	/* Reset minimum */
+	ret = regmap_bulk_write(regmap, reg, buf_min, num_regs);
+	if (ret)
+		return ret;
+
+	switch (reg) {
+	case LTC2945_MIN_POWER_H:
+		reg = LTC2945_MAX_POWER_H;
+		break;
+	case LTC2945_MIN_SENSE_H:
+		reg = LTC2945_MAX_SENSE_H;
+		break;
+	case LTC2945_MIN_VIN_H:
+		reg = LTC2945_MAX_VIN_H;
+		break;
+	case LTC2945_MIN_ADIN_H:
+		reg = LTC2945_MAX_ADIN_H;
+		break;
+	default:
+		BUG();
+		break;
+	}
+	/* Reset maximum */
+	ret = regmap_bulk_write(regmap, reg, buf_max, num_regs);
+
+	/* Try resetting test mode even if there was an error */
+	regmap_update_bits(regmap, LTC2945_CONTROL, CONTROL_TEST_MODE, 0);
+
+	return ret ? : count;
+}
+
+static ssize_t ltc2945_show_bool(struct device *dev,
+				 struct device_attribute *da, char *buf)
+{
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
+	struct regmap *regmap = dev_get_drvdata(dev);
+	unsigned int fault;
+	int ret;
+
+	ret = regmap_read(regmap, LTC2945_FAULT, &fault);
+	if (ret < 0)
+		return ret;
+
+	fault &= attr->index;
+	if (fault)		/* Clear reported faults in chip register */
+		regmap_update_bits(regmap, LTC2945_FAULT, attr->index, 0);
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", !!fault);
+}
+
+/* Input voltages */
+
+static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ltc2945_show_value, NULL,
+			  LTC2945_VIN_H);
+static SENSOR_DEVICE_ATTR(in1_min, S_IRUGO | S_IWUSR, ltc2945_show_value,
+			  ltc2945_set_value, LTC2945_MIN_VIN_THRES_H);
+static SENSOR_DEVICE_ATTR(in1_max, S_IRUGO | S_IWUSR, ltc2945_show_value,
+			  ltc2945_set_value, LTC2945_MAX_VIN_THRES_H);
+static SENSOR_DEVICE_ATTR(in1_lowest, S_IRUGO, ltc2945_show_value, NULL,
+			  LTC2945_MIN_VIN_H);
+static SENSOR_DEVICE_ATTR(in1_highest, S_IRUGO, ltc2945_show_value, NULL,
+			  LTC2945_MAX_VIN_H);
+static SENSOR_DEVICE_ATTR(in1_reset_history, S_IWUSR, NULL,
+			  ltc2945_reset_history, LTC2945_MIN_VIN_H);
+
+static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, ltc2945_show_value, NULL,
+			  LTC2945_ADIN_H);
+static SENSOR_DEVICE_ATTR(in2_min, S_IRUGO | S_IWUSR, ltc2945_show_value,
+			  ltc2945_set_value, LTC2945_MIN_ADIN_THRES_H);
+static SENSOR_DEVICE_ATTR(in2_max, S_IRUGO | S_IWUSR, ltc2945_show_value,
+			  ltc2945_set_value, LTC2945_MAX_ADIN_THRES_H);
+static SENSOR_DEVICE_ATTR(in2_lowest, S_IRUGO, ltc2945_show_value, NULL,
+			  LTC2945_MIN_ADIN_H);
+static SENSOR_DEVICE_ATTR(in2_highest, S_IRUGO, ltc2945_show_value, NULL,
+			  LTC2945_MAX_ADIN_H);
+static SENSOR_DEVICE_ATTR(in2_reset_history, S_IWUSR, NULL,
+			  ltc2945_reset_history, LTC2945_MIN_ADIN_H);
+
+/* Voltage alarms */
+
+static SENSOR_DEVICE_ATTR(in1_min_alarm, S_IRUGO, ltc2945_show_bool, NULL,
+			  FAULT_VIN_UV);
+static SENSOR_DEVICE_ATTR(in1_max_alarm, S_IRUGO, ltc2945_show_bool, NULL,
+			  FAULT_VIN_OV);
+static SENSOR_DEVICE_ATTR(in2_min_alarm, S_IRUGO, ltc2945_show_bool, NULL,
+			  FAULT_ADIN_UV);
+static SENSOR_DEVICE_ATTR(in2_max_alarm, S_IRUGO, ltc2945_show_bool, NULL,
+			  FAULT_ADIN_OV);
+
+/* Currents (via sense resistor) */
+
+static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, ltc2945_show_value, NULL,
+			  LTC2945_SENSE_H);
+static SENSOR_DEVICE_ATTR(curr1_min, S_IRUGO | S_IWUSR, ltc2945_show_value,
+			  ltc2945_set_value, LTC2945_MIN_SENSE_THRES_H);
+static SENSOR_DEVICE_ATTR(curr1_max, S_IRUGO | S_IWUSR, ltc2945_show_value,
+			  ltc2945_set_value, LTC2945_MAX_SENSE_THRES_H);
+static SENSOR_DEVICE_ATTR(curr1_lowest, S_IRUGO, ltc2945_show_value, NULL,
+			  LTC2945_MIN_SENSE_H);
+static SENSOR_DEVICE_ATTR(curr1_highest, S_IRUGO, ltc2945_show_value, NULL,
+			  LTC2945_MAX_SENSE_H);
+static SENSOR_DEVICE_ATTR(curr1_reset_history, S_IWUSR, NULL,
+			  ltc2945_reset_history, LTC2945_MIN_SENSE_H);
+
+/* Current alarms */
+
+static SENSOR_DEVICE_ATTR(curr1_min_alarm, S_IRUGO, ltc2945_show_bool, NULL,
+			  FAULT_SENSE_UV);
+static SENSOR_DEVICE_ATTR(curr1_max_alarm, S_IRUGO, ltc2945_show_bool, NULL,
+			  FAULT_SENSE_OV);
+
+/* Power */
+
+static SENSOR_DEVICE_ATTR(power1_input, S_IRUGO, ltc2945_show_value, NULL,
+			  LTC2945_POWER_H);
+static SENSOR_DEVICE_ATTR(power1_min, S_IRUGO | S_IWUSR, ltc2945_show_value,
+			  ltc2945_set_value, LTC2945_MIN_POWER_THRES_H);
+static SENSOR_DEVICE_ATTR(power1_max, S_IRUGO | S_IWUSR, ltc2945_show_value,
+			  ltc2945_set_value, LTC2945_MAX_POWER_THRES_H);
+static SENSOR_DEVICE_ATTR(power1_input_lowest, S_IRUGO, ltc2945_show_value,
+			  NULL, LTC2945_MIN_POWER_H);
+static SENSOR_DEVICE_ATTR(power1_input_highest, S_IRUGO, ltc2945_show_value,
+			  NULL, LTC2945_MAX_POWER_H);
+static SENSOR_DEVICE_ATTR(power1_reset_history, S_IWUSR, NULL,
+			  ltc2945_reset_history, LTC2945_MIN_POWER_H);
+
+/* Power alarms */
+
+static SENSOR_DEVICE_ATTR(power1_min_alarm, S_IRUGO, ltc2945_show_bool, NULL,
+			  FAULT_POWER_UV);
+static SENSOR_DEVICE_ATTR(power1_max_alarm, S_IRUGO, ltc2945_show_bool, NULL,
+			  FAULT_POWER_OV);
+
+static struct attribute *ltc2945_attrs[] = {
+	&sensor_dev_attr_in1_input.dev_attr.attr,
+	&sensor_dev_attr_in1_min.dev_attr.attr,
+	&sensor_dev_attr_in1_max.dev_attr.attr,
+	&sensor_dev_attr_in1_lowest.dev_attr.attr,
+	&sensor_dev_attr_in1_highest.dev_attr.attr,
+	&sensor_dev_attr_in1_reset_history.dev_attr.attr,
+	&sensor_dev_attr_in1_min_alarm.dev_attr.attr,
+	&sensor_dev_attr_in1_max_alarm.dev_attr.attr,
+
+	&sensor_dev_attr_in2_input.dev_attr.attr,
+	&sensor_dev_attr_in2_min.dev_attr.attr,
+	&sensor_dev_attr_in2_max.dev_attr.attr,
+	&sensor_dev_attr_in2_lowest.dev_attr.attr,
+	&sensor_dev_attr_in2_highest.dev_attr.attr,
+	&sensor_dev_attr_in2_reset_history.dev_attr.attr,
+	&sensor_dev_attr_in2_min_alarm.dev_attr.attr,
+	&sensor_dev_attr_in2_max_alarm.dev_attr.attr,
+
+	&sensor_dev_attr_curr1_input.dev_attr.attr,
+	&sensor_dev_attr_curr1_min.dev_attr.attr,
+	&sensor_dev_attr_curr1_max.dev_attr.attr,
+	&sensor_dev_attr_curr1_lowest.dev_attr.attr,
+	&sensor_dev_attr_curr1_highest.dev_attr.attr,
+	&sensor_dev_attr_curr1_reset_history.dev_attr.attr,
+	&sensor_dev_attr_curr1_min_alarm.dev_attr.attr,
+	&sensor_dev_attr_curr1_max_alarm.dev_attr.attr,
+
+	&sensor_dev_attr_power1_input.dev_attr.attr,
+	&sensor_dev_attr_power1_min.dev_attr.attr,
+	&sensor_dev_attr_power1_max.dev_attr.attr,
+	&sensor_dev_attr_power1_input_lowest.dev_attr.attr,
+	&sensor_dev_attr_power1_input_highest.dev_attr.attr,
+	&sensor_dev_attr_power1_reset_history.dev_attr.attr,
+	&sensor_dev_attr_power1_min_alarm.dev_attr.attr,
+	&sensor_dev_attr_power1_max_alarm.dev_attr.attr,
+
+	NULL,
+};
+ATTRIBUTE_GROUPS(ltc2945);
+
+static struct regmap_config ltc2945_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = LTC2945_MIN_ADIN_THRES_L,
+};
+
+static int ltc2945_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	struct device *dev = &client->dev;
+	struct device *hwmon_dev;
+	struct regmap *regmap;
+
+	regmap = devm_regmap_init_i2c(client, &ltc2945_regmap_config);
+	if (IS_ERR(regmap)) {
+		dev_err(dev, "failed to allocate register map\n");
+		return PTR_ERR(regmap);
+	}
+
+	/* Clear faults */
+	regmap_write(regmap, LTC2945_FAULT, 0x00);
+
+	hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
+							   regmap,
+							   ltc2945_groups);
+	return PTR_ERR_OR_ZERO(hwmon_dev);
+}
+
+static const struct i2c_device_id ltc2945_id[] = {
+	{"ltc2945", 0},
+	{ }
+};
+
+MODULE_DEVICE_TABLE(i2c, ltc2945_id);
+
+static struct i2c_driver ltc2945_driver = {
+	.driver = {
+		   .name = "ltc2945",
+		   },
+	.probe = ltc2945_probe,
+	.id_table = ltc2945_id,
+};
+
+module_i2c_driver(ltc2945_driver);
+
+MODULE_AUTHOR("Guenter Roeck <linux@roeck-us.net>");
+MODULE_DESCRIPTION("LTC2945 driver");
+MODULE_LICENSE("GPL");