hwmon: (max8688) Add support for peak attributes

Add support for voltage, current, and temperature peak (historic maximum)
attributes.
Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>

Documentation/hwmon/max8688

@@ -50,6 +50,8 @@ in1_min_alarm		Voltage low alarm. From VOLTAGE_UV_WARNING status.
 in1_max_alarm		Voltage high alarm. From VOLTAGE_OV_WARNING status.
 in1_lcrit_alarm		Voltage critical low alarm. From VOLTAGE_UV_FAULT status.
 in1_crit_alarm		Voltage critical high alarm. From VOLTAGE_OV_FAULT status.
+in1_highest		Historical maximum voltage.
+in1_reset_history	Write any value to reset history.
 
 curr1_label		"iout1"
 curr1_input		Measured current. From READ_IOUT register.
@@ -57,6 +59,8 @@ curr1_max		Maximum current. From IOUT_OC_WARN_LIMIT register.
 curr1_crit		Critical maximum current. From IOUT_OC_FAULT_LIMIT register.
 curr1_max_alarm		Current high alarm. From IOUT_OC_WARN_LIMIT register.
 curr1_crit_alarm	Current critical high alarm. From IOUT_OC_FAULT status.
+curr1_highest		Historical maximum current.
+curr1_reset_history	Write any value to reset history.
 
 temp1_input		Measured temperature. From READ_TEMPERATURE_1 register.
 temp1_max		Maximum temperature. From OT_WARN_LIMIT register.
@@ -67,3 +71,5 @@ temp1_max_alarm		Chip temperature high alarm. Set by comparing
 temp1_crit_alarm	Chip temperature critical high alarm. Set by comparing
 			READ_TEMPERATURE_1 with OT_FAULT_LIMIT if TEMP_OT_FAULT
 			status is set.
+temp1_highest		Historical maximum temperature.
+temp1_reset_history	Write any value to reset history.

drivers/hwmon/pmbus/max8688.c

@@ -25,6 +25,9 @@
 #include <linux/i2c.h>
 #include "pmbus.h"
 
+#define MAX8688_MFR_VOUT_PEAK		0xd4
+#define MAX8688_MFR_IOUT_PEAK		0xd5
+#define MAX8688_MFR_TEMPERATURE_PEAK	0xd6
 #define MAX8688_MFG_STATUS		0xd8
 
 #define MAX8688_STATUS_OC_FAULT		(1 << 4)
@@ -37,6 +40,62 @@
 #define MAX8688_STATUS_OT_FAULT		(1 << 13)
 #define MAX8688_STATUS_OT_WARNING	(1 << 14)
 
+static int max8688_read_word_data(struct i2c_client *client, int page, int reg)
+{
+	int ret;
+
+	if (page)
+		return -EINVAL;
+
+	switch (reg) {
+	case PMBUS_VIRT_READ_VOUT_MAX:
+		ret = pmbus_read_word_data(client, 0, MAX8688_MFR_VOUT_PEAK);
+		break;
+	case PMBUS_VIRT_READ_IOUT_MAX:
+		ret = pmbus_read_word_data(client, 0, MAX8688_MFR_IOUT_PEAK);
+		break;
+	case PMBUS_VIRT_READ_TEMP_MAX:
+		ret = pmbus_read_word_data(client, 0,
+					   MAX8688_MFR_TEMPERATURE_PEAK);
+		break;
+	case PMBUS_VIRT_RESET_VOUT_HISTORY:
+	case PMBUS_VIRT_RESET_IOUT_HISTORY:
+	case PMBUS_VIRT_RESET_TEMP_HISTORY:
+		ret = 0;
+		break;
+	default:
+		ret = -ENODATA;
+		break;
+	}
+	return ret;
+}
+
+static int max8688_write_word_data(struct i2c_client *client, int page, int reg,
+				   u16 word)
+{
+	int ret;
+
+	switch (reg) {
+	case PMBUS_VIRT_RESET_VOUT_HISTORY:
+		ret = pmbus_write_word_data(client, 0, MAX8688_MFR_VOUT_PEAK,
+					    0);
+		break;
+	case PMBUS_VIRT_RESET_IOUT_HISTORY:
+		ret = pmbus_write_word_data(client, 0, MAX8688_MFR_IOUT_PEAK,
+					    0);
+		break;
+	case PMBUS_VIRT_RESET_TEMP_HISTORY:
+		ret = pmbus_write_word_data(client, 0,
+					    MAX8688_MFR_TEMPERATURE_PEAK,
+					    0xffff);
+		break;
+	default:
+		ret = -ENODATA;
+		break;
+	}
+	return ret;
+}
+
 static int max8688_read_byte_data(struct i2c_client *client, int page, int reg)
 {
 	int ret = 0;
@@ -111,6 +170,8 @@ static struct pmbus_driver_info max8688_info = {
 		| PMBUS_HAVE_STATUS_VOUT | PMBUS_HAVE_STATUS_IOUT
 		| PMBUS_HAVE_STATUS_TEMP,
 	.read_byte_data = max8688_read_byte_data,
+	.read_word_data = max8688_read_word_data,
+	.write_word_data = max8688_write_word_data,
 };
 
 static int max8688_probe(struct i2c_client *client,