hwmon: (max34440) Add support for 'lowest' output voltage attribute

MAX34440 and compatibles support reporting the lowest measured output voltage.
Add support for it.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Jean Delvare <khali@linux-fr.org>

2 files changed, 10 insertions, 0 deletions

diff --git a/Documentation/hwmon/max34440 b/Documentation/hwmon/max34440
index 8ab51536a1eb..36b335c461dc 100644
--- a/Documentation/hwmon/max34440
+++ b/Documentation/hwmon/max34440
@@ -56,6 +56,7 @@ in[1-6]_min_alarm	Voltage low alarm. From VOLTAGE_UV_WARNING status.
 in[1-6]_max_alarm       Voltage high alarm. From VOLTAGE_OV_WARNING status.
 in[1-6]_lcrit_alarm     Voltage critical low alarm. From VOLTAGE_UV_FAULT status.
 in[1-6]_crit_alarm      Voltage critical high alarm. From VOLTAGE_OV_FAULT status.
+in[1-6]_lowest          Historical minimum voltage.
 in[1-6]_highest         Historical maximum voltage.
 in[1-6]_reset_history   Write any value to reset history.
 
diff --git a/drivers/hwmon/pmbus/max34440.c b/drivers/hwmon/pmbus/max34440.c
index 7d830c1e7032..95ee9e195cb6 100644
--- a/drivers/hwmon/pmbus/max34440.c
+++ b/drivers/hwmon/pmbus/max34440.c
@@ -30,6 +30,7 @@ enum chips { max34440, max34441 };
 #define MAX34440_MFR_VOUT_PEAK          0xd4
 #define MAX34440_MFR_IOUT_PEAK          0xd5
 #define MAX34440_MFR_TEMPERATURE_PEAK   0xd6
+#define MAX34440_MFR_VOUT_MIN           0xd7
 
 #define MAX34440_STATUS_OC_WARN         (1 << 0)
 #define MAX34440_STATUS_OC_FAULT        (1 << 1)
@@ -41,6 +42,10 @@ static int max34440_read_word_data(struct i2c_client *client, int page, int reg)
         int ret;
 
         switch (reg) {
+        case PMBUS_VIRT_READ_VOUT_MIN:
+                ret = pmbus_read_word_data(client, page,
+                                           MAX34440_MFR_VOUT_MIN);
+                break;
         case PMBUS_VIRT_READ_VOUT_MAX:
                 ret = pmbus_read_word_data(client, page,
                                            MAX34440_MFR_VOUT_PEAK);
@@ -73,6 +78,10 @@ static int max34440_write_word_data(struct i2c_client *client, int page,
         switch (reg) {
         case PMBUS_VIRT_RESET_VOUT_HISTORY:
                 ret = pmbus_write_word_data(client, page,
+                                            MAX34440_MFR_VOUT_MIN, 0x7fff);
+                if (ret)
+                        break;
+                ret = pmbus_write_word_data(client, page,
                                             MAX34440_MFR_VOUT_PEAK, 0);
                 break;
         case PMBUS_VIRT_RESET_IOUT_HISTORY: