hwmon: Driver for Linear Technologies LTC4222

Driver Linear Technologies LTC4222 Dual Hot Swap Controller
The driver currently only supports voltage monitoring, not voltage control.

Signed-off-by: Guenter Roeck <[e-mail]>

drivers/hwmon/Kconfig

···
 	  This driver can also be built as a module. If so, the module will
 	  be called ltc4215.
 
+config SENSORS_LTC4222
+	tristate "Linear Technology LTC4222"
+	depends on I2C
+	select REGMAP_I2C
+	default n
+	help
+	  If you say yes here you get support for Linear Technology LTC4222
+	  Dual Hot Swap Controller I2C interface.
+
+	  This driver can also be built as a module. If so, the module will
+	  be called ltc4222.
+
 config SENSORS_LTC4245
 	tristate "Linear Technology LTC4245"
 	depends on I2C

drivers/hwmon/Makefile

···
 obj-$(CONFIG_SENSORS_LM95245)	+= lm95245.o
 obj-$(CONFIG_SENSORS_LTC4151)	+= ltc4151.o
 obj-$(CONFIG_SENSORS_LTC4215)	+= ltc4215.o
+obj-$(CONFIG_SENSORS_LTC4222)	+= ltc4222.o
 obj-$(CONFIG_SENSORS_LTC4245)	+= ltc4245.o
 obj-$(CONFIG_SENSORS_LTC4261)	+= ltc4261.o
 obj-$(CONFIG_SENSORS_MAX1111)	+= max1111.o

drivers/hwmon/ltc4222.c

···
+/*
+ * Driver for Linear Technology LTC4222 Dual Hot Swap controller
+ *
+ * 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/bitops.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 LTC4222_CONTROL1	0xd0
+#define LTC4222_ALERT1		0xd1
+#define LTC4222_STATUS1		0xd2
+#define LTC4222_FAULT1		0xd3
+#define LTC4222_CONTROL2	0xd4
+#define LTC4222_ALERT2		0xd5
+#define LTC4222_STATUS2		0xd6
+#define LTC4222_FAULT2		0xd7
+#define LTC4222_SOURCE1		0xd8
+#define LTC4222_SOURCE2		0xda
+#define LTC4222_ADIN1		0xdc
+#define LTC4222_ADIN2		0xde
+#define LTC4222_SENSE1		0xe0
+#define LTC4222_SENSE2		0xe2
+#define LTC4222_ADC_CONTROL	0xe4
+
+/*
+ * Fault register bits
+ */
+#define FAULT_OV	BIT(0)
+#define FAULT_UV	BIT(1)
+#define FAULT_OC	BIT(2)
+#define FAULT_POWER_BAD	BIT(3)
+#define FAULT_FET_BAD	BIT(5)
+
+/* Return the voltage from the given register in mV or mA */
+static int ltc4222_get_value(struct device *dev, u8 reg)
+{
+	struct regmap *regmap = dev_get_drvdata(dev);
+	unsigned int val;
+	u8 buf[2];
+	int ret;
+
+	ret = regmap_bulk_read(regmap, reg, buf, 2);
+	if (ret < 0)
+		return ret;
+
+	val = ((buf[0] << 8) + buf[1]) >> 6;
+
+	switch (reg) {
+	case LTC4222_ADIN1:
+	case LTC4222_ADIN2:
+		/* 1.25 mV resolution. Convert to mV. */
+		val = DIV_ROUND_CLOSEST(val * 5, 4);
+		break;
+	case LTC4222_SOURCE1:
+	case LTC4222_SOURCE2:
+		/* 31.25 mV resolution. Convert to mV. */
+		val = DIV_ROUND_CLOSEST(val * 125, 4);
+		break;
+	case LTC4222_SENSE1:
+	case LTC4222_SENSE2:
+		/*
+		 * 62.5 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 * 125, 2);
+		break;
+	default:
+		return -EINVAL;
+	}
+	return val;
+}
+
+static ssize_t ltc4222_show_value(struct device *dev,
+				  struct device_attribute *da, char *buf)
+{
+	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
+	int value;
+
+	value = ltc4222_get_value(dev, attr->index);
+	if (value < 0)
+		return value;
+	return snprintf(buf, PAGE_SIZE, "%d\n", value);
+}
+
+static ssize_t ltc4222_show_bool(struct device *dev,
+				 struct device_attribute *da, char *buf)
+{
+	struct sensor_device_attribute_2 *attr = to_sensor_dev_attr_2(da);
+	struct regmap *regmap = dev_get_drvdata(dev);
+	unsigned int fault;
+	int ret;
+
+	ret = regmap_read(regmap, attr->nr, &fault);
+	if (ret < 0)
+		return ret;
+	fault &= attr->index;
+	if (fault)		/* Clear reported faults in chip register */
+		regmap_update_bits(regmap, attr->nr, attr->index, 0);
+
+	return snprintf(buf, PAGE_SIZE, "%d\n", !!fault);
+}
+
+/* Voltages */
+static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ltc4222_show_value, NULL,
+			  LTC4222_SOURCE1);
+static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, ltc4222_show_value, NULL,
+			  LTC4222_ADIN1);
+static SENSOR_DEVICE_ATTR(in3_input, S_IRUGO, ltc4222_show_value, NULL,
+			  LTC4222_SOURCE2);
+static SENSOR_DEVICE_ATTR(in4_input, S_IRUGO, ltc4222_show_value, NULL,
+			  LTC4222_ADIN2);
+
+/*
+ * Voltage alarms
+ * UV/OV faults are associated with the input voltage, and power bad and fet
+ * faults are associated with the output voltage.
+ */
+static SENSOR_DEVICE_ATTR_2(in1_min_alarm, S_IRUGO, ltc4222_show_bool, NULL,
+			    LTC4222_FAULT1, FAULT_UV);
+static SENSOR_DEVICE_ATTR_2(in1_max_alarm, S_IRUGO, ltc4222_show_bool, NULL,
+			    LTC4222_FAULT1, FAULT_OV);
+static SENSOR_DEVICE_ATTR_2(in2_alarm, S_IRUGO, ltc4222_show_bool, NULL,
+			    LTC4222_FAULT1, FAULT_POWER_BAD | FAULT_FET_BAD);
+
+static SENSOR_DEVICE_ATTR_2(in3_min_alarm, S_IRUGO, ltc4222_show_bool, NULL,
+			    LTC4222_FAULT2, FAULT_UV);
+static SENSOR_DEVICE_ATTR_2(in3_max_alarm, S_IRUGO, ltc4222_show_bool, NULL,
+			    LTC4222_FAULT2, FAULT_OV);
+static SENSOR_DEVICE_ATTR_2(in4_alarm, S_IRUGO, ltc4222_show_bool, NULL,
+			    LTC4222_FAULT2, FAULT_POWER_BAD | FAULT_FET_BAD);
+
+/* Current (via sense resistor) */
+static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, ltc4222_show_value, NULL,
+			  LTC4222_SENSE1);
+static SENSOR_DEVICE_ATTR(curr2_input, S_IRUGO, ltc4222_show_value, NULL,
+			  LTC4222_SENSE2);
+
+/* Overcurrent alarm */
+static SENSOR_DEVICE_ATTR_2(curr1_max_alarm, S_IRUGO, ltc4222_show_bool, NULL,
+			    LTC4222_FAULT1, FAULT_OC);
+static SENSOR_DEVICE_ATTR_2(curr2_max_alarm, S_IRUGO, ltc4222_show_bool, NULL,
+			    LTC4222_FAULT2, FAULT_OC);
+
+static struct attribute *ltc4222_attrs[] = {
+	&sensor_dev_attr_in1_input.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_alarm.dev_attr.attr,
+	&sensor_dev_attr_in3_input.dev_attr.attr,
+	&sensor_dev_attr_in3_min_alarm.dev_attr.attr,
+	&sensor_dev_attr_in3_max_alarm.dev_attr.attr,
+	&sensor_dev_attr_in4_input.dev_attr.attr,
+	&sensor_dev_attr_in4_alarm.dev_attr.attr,
+
+	&sensor_dev_attr_curr1_input.dev_attr.attr,
+	&sensor_dev_attr_curr1_max_alarm.dev_attr.attr,
+	&sensor_dev_attr_curr2_input.dev_attr.attr,
+	&sensor_dev_attr_curr2_max_alarm.dev_attr.attr,
+
+	NULL,
+};
+ATTRIBUTE_GROUPS(ltc4222);
+
+static struct regmap_config ltc4222_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+	.max_register = LTC4222_ADC_CONTROL,
+};
+
+static int ltc4222_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, &ltc4222_regmap_config);
+	if (IS_ERR(regmap)) {
+		dev_err(dev, "failed to allocate register map\n");
+		return PTR_ERR(regmap);
+	}
+
+	/* Clear faults */
+	regmap_write(regmap, LTC4222_FAULT1, 0x00);
+	regmap_write(regmap, LTC4222_FAULT2, 0x00);
+
+	hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
+							   regmap,
+							   ltc4222_groups);
+	return PTR_ERR_OR_ZERO(hwmon_dev);
+}
+
+static const struct i2c_device_id ltc4222_id[] = {
+	{"ltc4222", 0},
+	{ }
+};
+
+MODULE_DEVICE_TABLE(i2c, ltc4222_id);
+
+static struct i2c_driver ltc4222_driver = {
+	.driver = {
+		   .name = "ltc4222",
+		   },
+	.probe = ltc4222_probe,
+	.id_table = ltc4222_id,
+};
+
+module_i2c_driver(ltc4222_driver);
+
+MODULE_AUTHOR("Guenter Roeck <[e-mail]>");
+MODULE_DESCRIPTION("LTC4222 driver");
+MODULE_LICENSE("GPL");