hwmon: (pmbus) Add client driver for LTC3815

LTC3815 is a Monolithic Synchronous DC/DC Step-Down Converter.

Cc: Michael Jones <mike@proclivis.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/hwmon/ltc3815

+Kernel driver ltc3815
+=====================
+
+Supported chips:
+  * Linear Technology LTC3815
+    Prefix: 'ltc3815'
+    Addresses scanned: -
+    Datasheet: http://www.linear.com/product/ltc3815
+
+Author: Guenter Roeck <linux@roeck-us.net>
+
+
+Description
+-----------
+
+LTC3815 is a Monolithic Synchronous DC/DC Step-Down Converter.
+
+
+Usage Notes
+-----------
+
+This driver does not probe for PMBus devices. You will have to instantiate
+devices explicitly.
+
+Example: the following commands will load the driver for an LTC3815
+at address 0x20 on I2C bus #1:
+
+# modprobe ltc3815
+# echo ltc3815 0x20 > /sys/bus/i2c/devices/i2c-1/new_device
+
+
+Sysfs attributes
+----------------
+
+in1_label		"vin"
+in1_input		Measured input voltage.
+in1_alarm		Input voltage alarm.
+in1_highest		Highest input voltage.
+in1_reset_history	Reset input voltage history.
+
+in2_label		"vout1".
+in2_input		Measured output voltage.
+in2_alarm		Output voltage alarm.
+in2_highest		Highest output voltage.
+in2_reset_history	Reset output voltage history.
+
+temp1_input		Measured chip temperature.
+temp1_alarm		Temperature alarm.
+temp1_highest		Highest measured temperature.
+temp1_reset_history	Reset temperature history.
+
+curr1_label		"iin".
+curr1_input		Measured input current.
+curr1_highest		Highest input current.
+curr1_reset_history	Reset input current history.
+
+curr2_label		"iout1".
+curr2_input		Measured output current.
+curr2_alarm		Output current alarm.
+curr2_highest		Highest output current.
+curr2_reset_history	Reset output current history.

drivers/hwmon/pmbus/Kconfig

@@ -65,6 +65,16 @@ config SENSORS_LTC2978_REGULATOR
 	  If you say yes here you get regulator support for Linear
 	  Technology LTC2974, LTC2977, LTC2978, LTC3880, LTC3883, and LTM4676.
 
+config SENSORS_LTC3815
+	tristate "Linear Technologies LTC3815"
+	default n
+	help
+	  If you say yes here you get hardware monitoring support for Linear
+	  Technology LTC3815.
+
+	  This driver can also be built as a module. If so, the module will
+	  be called ltc3815.
+
 config SENSORS_MAX16064
 	tristate "Maxim MAX16064"
 	default n

drivers/hwmon/pmbus/Makefile

@@ -7,6 +7,7 @@ obj-$(CONFIG_SENSORS_PMBUS)	+= pmbus.o
 obj-$(CONFIG_SENSORS_ADM1275)	+= adm1275.o
 obj-$(CONFIG_SENSORS_LM25066)	+= lm25066.o
 obj-$(CONFIG_SENSORS_LTC2978)	+= ltc2978.o
+obj-$(CONFIG_SENSORS_LTC3815)	+= ltc3815.o
 obj-$(CONFIG_SENSORS_MAX16064)	+= max16064.o
 obj-$(CONFIG_SENSORS_MAX20751)	+= max20751.o
 obj-$(CONFIG_SENSORS_MAX34440)	+= max34440.o

drivers/hwmon/pmbus/ltc3815.c

+/*
+ * Hardware monitoring driver for LTC3815
+ *
+ * Copyright (c) 2015 Linear Technology
+ * Copyright (c) 2015 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/err.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/jiffies.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include "pmbus.h"
+
+#define LTC3815_MFR_IOUT_PEAK	0xd7
+#define LTC3815_MFR_VOUT_PEAK	0xdd
+#define LTC3815_MFR_VIN_PEAK	0xde
+#define LTC3815_MFR_TEMP_PEAK	0xdf
+#define LTC3815_MFR_IIN_PEAK	0xe1
+#define LTC3815_MFR_SPECIAL_ID	0xe7
+
+#define LTC3815_ID		0x8000
+#define LTC3815_ID_MASK		0xff00
+
+static int ltc3815_read_byte_data(struct i2c_client *client, int page, int reg)
+{
+	int ret;
+
+	switch (reg) {
+	case PMBUS_VOUT_MODE:
+		/*
+		 * The chip returns 0x3e, suggesting VID mode with manufacturer
+		 * specific VID codes. Since the output voltage is reported
+		 * with a LSB of 0.5mV, override and report direct mode with
+		 * appropriate coefficients.
+		 */
+		ret = 0x40;
+		break;
+	default:
+		ret = -ENODATA;
+		break;
+	}
+	return ret;
+}
+
+static int ltc3815_write_byte(struct i2c_client *client, int page, u8 reg)
+{
+	int ret;
+
+	switch (reg) {
+	case PMBUS_CLEAR_FAULTS:
+		/*
+		 * LTC3815 does not support the CLEAR_FAULTS command.
+		 * Emulate it by clearing the status register.
+		 */
+		ret = pmbus_read_word_data(client, 0, PMBUS_STATUS_WORD);
+		if (ret > 0) {
+			pmbus_write_word_data(client, 0, PMBUS_STATUS_WORD,
+					      ret);
+			ret = 0;
+		}
+		break;
+	default:
+		ret = -ENODATA;
+		break;
+	}
+	return ret;
+}
+
+static int ltc3815_read_word_data(struct i2c_client *client, int page, int reg)
+{
+	int ret;
+
+	switch (reg) {
+	case PMBUS_VIRT_READ_VIN_MAX:
+		ret = pmbus_read_word_data(client, page, LTC3815_MFR_VIN_PEAK);
+		break;
+	case PMBUS_VIRT_READ_VOUT_MAX:
+		ret = pmbus_read_word_data(client, page, LTC3815_MFR_VOUT_PEAK);
+		break;
+	case PMBUS_VIRT_READ_TEMP_MAX:
+		ret = pmbus_read_word_data(client, page, LTC3815_MFR_TEMP_PEAK);
+		break;
+	case PMBUS_VIRT_READ_IOUT_MAX:
+		ret = pmbus_read_word_data(client, page, LTC3815_MFR_IOUT_PEAK);
+		break;
+	case PMBUS_VIRT_READ_IIN_MAX:
+		ret = pmbus_read_word_data(client, page, LTC3815_MFR_IIN_PEAK);
+		break;
+	case PMBUS_VIRT_RESET_VOUT_HISTORY:
+	case PMBUS_VIRT_RESET_VIN_HISTORY:
+	case PMBUS_VIRT_RESET_TEMP_HISTORY:
+	case PMBUS_VIRT_RESET_IOUT_HISTORY:
+	case PMBUS_VIRT_RESET_IIN_HISTORY:
+		ret = 0;
+		break;
+	default:
+		ret = -ENODATA;
+		break;
+	}
+	return ret;
+}
+
+static int ltc3815_write_word_data(struct i2c_client *client, int page,
+				   int reg, u16 word)
+{
+	int ret;
+
+	switch (reg) {
+	case PMBUS_VIRT_RESET_IIN_HISTORY:
+		ret = pmbus_write_word_data(client, page,
+					    LTC3815_MFR_IIN_PEAK, 0);
+		break;
+	case PMBUS_VIRT_RESET_IOUT_HISTORY:
+		ret = pmbus_write_word_data(client, page,
+					    LTC3815_MFR_IOUT_PEAK, 0);
+		break;
+	case PMBUS_VIRT_RESET_VOUT_HISTORY:
+		ret = pmbus_write_word_data(client, page,
+					    LTC3815_MFR_VOUT_PEAK, 0);
+		break;
+	case PMBUS_VIRT_RESET_VIN_HISTORY:
+		ret = pmbus_write_word_data(client, page,
+					    LTC3815_MFR_VIN_PEAK, 0);
+		break;
+	case PMBUS_VIRT_RESET_TEMP_HISTORY:
+		ret = pmbus_write_word_data(client, page,
+					    LTC3815_MFR_TEMP_PEAK, 0);
+		break;
+	default:
+		ret = -ENODATA;
+		break;
+	}
+	return ret;
+}
+
+static const struct i2c_device_id ltc3815_id[] = {
+	{"ltc3815", 0},
+	{ }
+};
+MODULE_DEVICE_TABLE(i2c, ltc3815_id);
+
+static struct pmbus_driver_info ltc3815_info = {
+	.pages = 1,
+	.format[PSC_VOLTAGE_IN] = direct,
+	.format[PSC_VOLTAGE_OUT] = direct,
+	.format[PSC_CURRENT_IN] = direct,
+	.format[PSC_CURRENT_OUT] = direct,
+	.format[PSC_TEMPERATURE] = direct,
+	.m[PSC_VOLTAGE_IN] = 250,
+	.b[PSC_VOLTAGE_IN] = 0,
+	.R[PSC_VOLTAGE_IN] = 0,
+	.m[PSC_VOLTAGE_OUT] = 2,
+	.b[PSC_VOLTAGE_OUT] = 0,
+	.R[PSC_VOLTAGE_OUT] = 3,
+	.m[PSC_CURRENT_IN] = 1,
+	.b[PSC_CURRENT_IN] = 0,
+	.R[PSC_CURRENT_IN] = 2,
+	.m[PSC_CURRENT_OUT] = 1,
+	.b[PSC_CURRENT_OUT] = 0,
+	.R[PSC_CURRENT_OUT] = 2,
+	.m[PSC_TEMPERATURE] = 1,
+	.b[PSC_TEMPERATURE] = 0,
+	.R[PSC_TEMPERATURE] = 0,
+	.func[0] = PMBUS_HAVE_VIN | PMBUS_HAVE_IIN | PMBUS_HAVE_VOUT |
+		PMBUS_HAVE_IOUT | PMBUS_HAVE_TEMP,
+	.read_byte_data = ltc3815_read_byte_data,
+	.read_word_data = ltc3815_read_word_data,
+	.write_byte = ltc3815_write_byte,
+	.write_word_data = ltc3815_write_word_data,
+};
+
+static int ltc3815_probe(struct i2c_client *client,
+			 const struct i2c_device_id *id)
+{
+	int chip_id;
+
+	if (!i2c_check_functionality(client->adapter,
+				     I2C_FUNC_SMBUS_READ_WORD_DATA))
+		return -ENODEV;
+
+	chip_id = i2c_smbus_read_word_data(client, LTC3815_MFR_SPECIAL_ID);
+	if (chip_id < 0)
+		return chip_id;
+	if ((chip_id & LTC3815_ID_MASK) != LTC3815_ID)
+		return -ENODEV;
+
+	return pmbus_do_probe(client, id, &ltc3815_info);
+}
+
+static struct i2c_driver ltc3815_driver = {
+	.driver = {
+		   .name = "ltc3815",
+		   },
+	.probe = ltc3815_probe,
+	.remove = pmbus_do_remove,
+	.id_table = ltc3815_id,
+};
+
+module_i2c_driver(ltc3815_driver);
+
+MODULE_AUTHOR("Guenter Roeck");
+MODULE_DESCRIPTION("PMBus driver for LTC3815");
+MODULE_LICENSE("GPL");