hwmon: (pmbus/zl6100) Add support for VMON/VDRV

Some of the ZL6100 compatible chips support monitoring a separate voltage pin,
VMON (ZL2004) or VDRV (ZL91xx). Report it as in2 / vmon.

The chips support implicit warning limits for VMON/VDRV, as percentage of the
respective critical voltage. Support by reading/writing the critical voltages
and calculating the associated warning voltages.

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

2 files changed, 188 insertions, 14 deletions

diff --git a/Documentation/hwmon/zl6100 b/Documentation/hwmon/zl6100
index a995b41724fd..3d924b6b59e9 100644
--- a/Documentation/hwmon/zl6100
+++ b/Documentation/hwmon/zl6100
@@ -121,12 +121,26 @@ in1_max_alarm		Input voltage high alarm.
 in1_lcrit_alarm         Input voltage critical low alarm.
 in1_crit_alarm          Input voltage critical high alarm.
 
-in2_label               "vout1"
-in2_input               Measured output voltage.
-in2_lcrit               Critical minimum output Voltage.
-in2_crit                Critical maximum output voltage.
-in2_lcrit_alarm         Critical output voltage critical low alarm.
-in2_crit_alarm          Critical output voltage critical high alarm.
+in2_label               "vmon"
+in2_input               Measured voltage on VMON (ZL2004) or VDRV (ZL9101M,
+                        ZL9117M) pin. Reported voltage is 16x the voltage on the
+                        pin (adjusted internally by the chip).
+in2_lcrit               Critical minumum VMON/VDRV Voltage.
+in2_crit                Critical maximum VMON/VDRV voltage.
+in2_lcrit_alarm         VMON/VDRV voltage critical low alarm.
+in2_crit_alarm          VMON/VDRV voltage critical high alarm.
+
+                        vmon attributes are supported on ZL2004, ZL9101M,
+                        and ZL9117M only.
+
+inX_label               "vout1"
+inX_input               Measured output voltage.
+inX_lcrit               Critical minimum output Voltage.
+inX_crit                Critical maximum output voltage.
+inX_lcrit_alarm         Critical output voltage critical low alarm.
+inX_crit_alarm          Critical output voltage critical high alarm.
+
+                        X is 3 for ZL2004, ZL9101M, and ZL9117M, 2 otherwise.
 
 curr1_label             "iout1"
 curr1_input             Measured output current.
diff --git a/drivers/hwmon/pmbus/zl6100.c b/drivers/hwmon/pmbus/zl6100.c
index fc5eed8e85bb..819644121259 100644
--- a/drivers/hwmon/pmbus/zl6100.c
+++ b/drivers/hwmon/pmbus/zl6100.c
@@ -2,6 +2,7 @@
  * Hardware monitoring driver for ZL6100 and compatibles
  *
  * Copyright (c) 2011 Ericsson AB.
+ * Copyright (c) 2012 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
@@ -45,12 +46,87 @@ struct zl6100_data {
 
 #define ZL6100_MFR_XTEMP_ENABLE         (1 << 7)
 
+#define MFR_VMON_OV_FAULT_LIMIT         0xf5
+#define MFR_VMON_UV_FAULT_LIMIT         0xf6
+#define MFR_READ_VMON                   0xf7
+
+#define VMON_UV_WARNING                 (1 << 5)
+#define VMON_OV_WARNING                 (1 << 4)
+#define VMON_UV_FAULT                   (1 << 1)
+#define VMON_OV_FAULT                   (1 << 0)
+
 #define ZL6100_WAIT_TIME                1000    /* uS   */
 
 static ushort delay = ZL6100_WAIT_TIME;
 module_param(delay, ushort, 0644);
 MODULE_PARM_DESC(delay, "Delay between chip accesses in uS");
 
+/* Convert linear sensor value to milli-units */
+static long zl6100_l2d(s16 l)
+{
+        s16 exponent;
+        s32 mantissa;
+        long val;
+
+        exponent = l >> 11;
+        mantissa = ((s16)((l & 0x7ff) << 5)) >> 5;
+
+        val = mantissa;
+
+        /* scale result to milli-units */
+        val = val * 1000L;
+
+        if (exponent >= 0)
+                val <<= exponent;
+        else
+                val >>= -exponent;
+
+        return val;
+}
+
+#define MAX_MANTISSA    (1023 * 1000)
+#define MIN_MANTISSA    (511 * 1000)
+
+static u16 zl6100_d2l(long val)
+{
+        s16 exponent = 0, mantissa;
+        bool negative = false;
+
+        /* simple case */
+        if (val == 0)
+                return 0;
+
+        if (val < 0) {
+                negative = true;
+                val = -val;
+        }
+
+        /* Reduce large mantissa until it fits into 10 bit */
+        while (val >= MAX_MANTISSA && exponent < 15) {
+                exponent++;
+                val >>= 1;
+        }
+        /* Increase small mantissa to improve precision */
+        while (val < MIN_MANTISSA && exponent > -15) {
+                exponent--;
+                val <<= 1;
+        }
+
+        /* Convert mantissa from milli-units to units */
+        mantissa = DIV_ROUND_CLOSEST(val, 1000);
+
+        /* Ensure that resulting number is within range */
+        if (mantissa > 0x3ff)
+                mantissa = 0x3ff;
+
+        /* restore sign */
+        if (negative)
+                mantissa = -mantissa;
+
+        /* Convert to 5 bit exponent, 11 bit mantissa */
+        return (mantissa & 0x7ff) | ((exponent << 11) & 0xf800);
+}
+
 /* Some chips need a delay between accesses */
 static inline void zl6100_wait(const struct zl6100_data *data)
 {
@@ -65,9 +141,9 @@ static int zl6100_read_word_data(struct i2c_client *client, int page, int reg)
 {
         const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
         struct zl6100_data *data = to_zl6100_data(info);
-        int ret;
+        int ret, vreg;
 
-        if (page || reg >= PMBUS_VIRT_BASE)
+        if (page > 0)
                 return -ENXIO;
 
         if (data->id == zl2005) {
@@ -83,9 +159,39 @@ static int zl6100_read_word_data(struct i2c_client *client, int page, int reg)
                 }
         }
 
+        switch (reg) {
+        case PMBUS_VIRT_READ_VMON:
+                vreg = MFR_READ_VMON;
+                break;
+        case PMBUS_VIRT_VMON_OV_WARN_LIMIT:
+        case PMBUS_VIRT_VMON_OV_FAULT_LIMIT:
+                vreg = MFR_VMON_OV_FAULT_LIMIT;
+                break;
+        case PMBUS_VIRT_VMON_UV_WARN_LIMIT:
+        case PMBUS_VIRT_VMON_UV_FAULT_LIMIT:
+                vreg = MFR_VMON_UV_FAULT_LIMIT;
+                break;
+        default:
+                if (reg >= PMBUS_VIRT_BASE)
+                        return -ENXIO;
+                vreg = reg;
+                break;
+        }
+
         zl6100_wait(data);
-        ret = pmbus_read_word_data(client, page, reg);
+        ret = pmbus_read_word_data(client, page, vreg);
         data->access = ktime_get();
+        if (ret < 0)
+                return ret;
+
+        switch (reg) {
+        case PMBUS_VIRT_VMON_OV_WARN_LIMIT:
+                ret = zl6100_d2l(DIV_ROUND_CLOSEST(zl6100_l2d(ret) * 9, 10));
+                break;
+        case PMBUS_VIRT_VMON_UV_WARN_LIMIT:
+                ret = zl6100_d2l(DIV_ROUND_CLOSEST(zl6100_l2d(ret) * 11, 10));
+                break;
+        }
 
         return ret;
 }
@@ -94,13 +200,35 @@ static int zl6100_read_byte_data(struct i2c_client *client, int page, int reg)
 {
         const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
         struct zl6100_data *data = to_zl6100_data(info);
-        int ret;
+        int ret, status;
 
         if (page > 0)
                 return -ENXIO;
 
         zl6100_wait(data);
-        ret = pmbus_read_byte_data(client, page, reg);
+
+        switch (reg) {
+        case PMBUS_VIRT_STATUS_VMON:
+                ret = pmbus_read_byte_data(client, 0,
+                                           PMBUS_STATUS_MFR_SPECIFIC);
+                if (ret < 0)
+                        break;
+
+                status = 0;
+                if (ret & VMON_UV_WARNING)
+                        status |= PB_VOLTAGE_UV_WARNING;
+                if (ret & VMON_OV_WARNING)
+                        status |= PB_VOLTAGE_OV_WARNING;
+                if (ret & VMON_UV_FAULT)
+                        status |= PB_VOLTAGE_UV_FAULT;
+                if (ret & VMON_OV_FAULT)
+                        status |= PB_VOLTAGE_OV_FAULT;
+                ret = status;
+                break;
+        default:
+                ret = pmbus_read_byte_data(client, page, reg);
+                break;
+        }
         data->access = ktime_get();
 
         return ret;
@@ -111,13 +239,38 @@ static int zl6100_write_word_data(struct i2c_client *client, int page, int reg,
 {
         const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
         struct zl6100_data *data = to_zl6100_data(info);
-        int ret;
+        int ret, vreg;
 
-        if (page || reg >= PMBUS_VIRT_BASE)
+        if (page > 0)
                 return -ENXIO;
 
+        switch (reg) {
+        case PMBUS_VIRT_VMON_OV_WARN_LIMIT:
+                word = zl6100_d2l(DIV_ROUND_CLOSEST(zl6100_l2d(word) * 10, 9));
+                vreg = MFR_VMON_OV_FAULT_LIMIT;
+                pmbus_clear_cache(client);
+                break;
+        case PMBUS_VIRT_VMON_OV_FAULT_LIMIT:
+                vreg = MFR_VMON_OV_FAULT_LIMIT;
+                pmbus_clear_cache(client);
+                break;
+        case PMBUS_VIRT_VMON_UV_WARN_LIMIT:
+                word = zl6100_d2l(DIV_ROUND_CLOSEST(zl6100_l2d(word) * 10, 11));
+                vreg = MFR_VMON_UV_FAULT_LIMIT;
+                pmbus_clear_cache(client);
+                break;
+        case PMBUS_VIRT_VMON_UV_FAULT_LIMIT:
+                vreg = MFR_VMON_UV_FAULT_LIMIT;
+                pmbus_clear_cache(client);
+                break;
+        default:
+                if (reg >= PMBUS_VIRT_BASE)
+                        return -ENXIO;
+                vreg = reg;
+        }
+
         zl6100_wait(data);
-        ret = pmbus_write_word_data(client, page, reg, word);
+        ret = pmbus_write_word_data(client, page, vreg, word);
         data->access = ktime_get();
 
         return ret;
@@ -225,6 +378,13 @@ static int zl6100_probe(struct i2c_client *client,
           | PMBUS_HAVE_IOUT | PMBUS_HAVE_STATUS_IOUT
           | PMBUS_HAVE_TEMP | PMBUS_HAVE_STATUS_TEMP;
 
+        /*
+         * ZL2004, ZL9101M, and ZL9117M support monitoring an extra voltage
+         * (VMON for ZL2004, VDRV for ZL9101M and ZL9117M). Report it as vmon.
+         */
+        if (data->id == zl2004 || data->id == zl9101 || data->id == zl9117)
+                info->func[0] |= PMBUS_HAVE_VMON | PMBUS_HAVE_STATUS_VMON;
+
         ret = i2c_smbus_read_word_data(client, ZL6100_MFR_CONFIG);
         if (ret < 0)
                 return ret;