hwmon: (pmbus) Support per-page exponent in linear mode

Some chips use different exponents for sensors on different pages
or rails. Detect and store exponent per page to support this situation.

This fixes a problem with wrong voltages seen on UCD90120.

Reported-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Tested-by: Soren Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

1 files changed, 36 insertions, 32 deletions

diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
index 3cbf66e9d861..291d11fe93e7 100644
--- a/drivers/hwmon/pmbus/pmbus_core.c
+++ b/drivers/hwmon/pmbus/pmbus_core.c
@@ -90,7 +90,8 @@ struct pmbus_data {
 
         u32 flags;              /* from platform data */
 
-        int exponent;           /* linear mode: exponent for output voltages */
+        int exponent[PMBUS_PAGES];
+                                /* linear mode: exponent for output voltages */
 
         const struct pmbus_driver_info *info;
 
@@ -410,7 +411,7 @@ static long pmbus_reg2data_linear(struct pmbus_data *data,
         long val;
 
         if (sensor->class == PSC_VOLTAGE_OUT) { /* LINEAR16 */
-                exponent = data->exponent;
+                exponent = data->exponent[sensor->page];
                 mantissa = (u16) sensor->data;
         } else {                                /* LINEAR11 */
                 exponent = ((s16)sensor->data) >> 11;
@@ -516,7 +517,7 @@ static long pmbus_reg2data(struct pmbus_data *data, struct pmbus_sensor *sensor)
 #define MIN_MANTISSA    (511 * 1000)
 
 static u16 pmbus_data2reg_linear(struct pmbus_data *data,
-                                 enum pmbus_sensor_classes class, long val)
+                                 struct pmbus_sensor *sensor, long val)
 {
         s16 exponent = 0, mantissa;
         bool negative = false;
@@ -525,7 +526,7 @@ static u16 pmbus_data2reg_linear(struct pmbus_data *data,
         if (val == 0)
                 return 0;
 
-        if (class == PSC_VOLTAGE_OUT) {
+        if (sensor->class == PSC_VOLTAGE_OUT) {
                 /* LINEAR16 does not support negative voltages */
                 if (val < 0)
                         return 0;
@@ -534,10 +535,10 @@ static u16 pmbus_data2reg_linear(struct pmbus_data *data,
                  * For a static exponents, we don't have a choice
                  * but to adjust the value to it.
                  */
-                if (data->exponent < 0)
-                        val <<= -data->exponent;
+                if (data->exponent[sensor->page] < 0)
+                        val <<= -data->exponent[sensor->page];
                 else
-                        val >>= data->exponent;
+                        val >>= data->exponent[sensor->page];
                 val = DIV_ROUND_CLOSEST(val, 1000);
                 return val & 0xffff;
         }
@@ -548,14 +549,14 @@ static u16 pmbus_data2reg_linear(struct pmbus_data *data,
         }
 
         /* Power is in uW. Convert to mW before converting. */
-        if (class == PSC_POWER)
+        if (sensor->class == PSC_POWER)
                 val = DIV_ROUND_CLOSEST(val, 1000L);
 
         /*
          * For simplicity, convert fan data to milli-units
          * before calculating the exponent.
          */
-        if (class == PSC_FAN)
+        if (sensor->class == PSC_FAN)
                 val = val * 1000;
 
         /* Reduce large mantissa until it fits into 10 bit */
@@ -585,22 +586,22 @@ static u16 pmbus_data2reg_linear(struct pmbus_data *data,
 }
 
 static u16 pmbus_data2reg_direct(struct pmbus_data *data,
-                                 enum pmbus_sensor_classes class, long val)
+                                 struct pmbus_sensor *sensor, long val)
 {
         long m, b, R;
 
-        m = data->info->m[class];
-        b = data->info->b[class];
-        R = data->info->R[class];
+        m = data->info->m[sensor->class];
+        b = data->info->b[sensor->class];
+        R = data->info->R[sensor->class];
 
         /* Power is in uW. Adjust R and b. */
-        if (class == PSC_POWER) {
+        if (sensor->class == PSC_POWER) {
                 R -= 3;
                 b *= 1000;
         }
 
         /* Calculate Y = (m * X + b) * 10^R */
-        if (class != PSC_FAN) {
+        if (sensor->class != PSC_FAN) {
                 R -= 3;         /* Adjust R and b for data in milli-units */
                 b *= 1000;
         }
@@ -619,7 +620,7 @@ static u16 pmbus_data2reg_direct(struct pmbus_data *data,
 }
 
 static u16 pmbus_data2reg_vid(struct pmbus_data *data,
-                              enum pmbus_sensor_classes class, long val)
+                              struct pmbus_sensor *sensor, long val)
 {
         val = clamp_val(val, 500, 1600);
 
@@ -627,20 +628,20 @@ static u16 pmbus_data2reg_vid(struct pmbus_data *data,
 }
 
 static u16 pmbus_data2reg(struct pmbus_data *data,
-                          enum pmbus_sensor_classes class, long val)
+                          struct pmbus_sensor *sensor, long val)
 {
         u16 regval;
 
-        switch (data->info->format[class]) {
+        switch (data->info->format[sensor->class]) {
         case direct:
-                regval = pmbus_data2reg_direct(data, class, val);
+                regval = pmbus_data2reg_direct(data, sensor, val);
                 break;
         case vid:
-                regval = pmbus_data2reg_vid(data, class, val);
+                regval = pmbus_data2reg_vid(data, sensor, val);
                 break;
         case linear:
         default:
-                regval = pmbus_data2reg_linear(data, class, val);
+                regval = pmbus_data2reg_linear(data, sensor, val);
                 break;
         }
         return regval;
@@ -746,7 +747,7 @@ static ssize_t pmbus_set_sensor(struct device *dev,
                 return -EINVAL;
 
         mutex_lock(&data->update_lock);
-        regval = pmbus_data2reg(data, sensor->class, val);
+        regval = pmbus_data2reg(data, sensor, val);
         ret = _pmbus_write_word_data(client, sensor->page, sensor->reg, regval);
         if (ret < 0)
                 rv = ret;
@@ -1643,12 +1644,13 @@ static int pmbus_find_attributes(struct i2c_client *client,
  * This function is called for all chips.
  */
 static int pmbus_identify_common(struct i2c_client *client,
-                                 struct pmbus_data *data)
+                                 struct pmbus_data *data, int page)
 {
         int vout_mode = -1;
 
-        if (pmbus_check_byte_register(client, 0, PMBUS_VOUT_MODE))
-                vout_mode = _pmbus_read_byte_data(client, 0, PMBUS_VOUT_MODE);
+        if (pmbus_check_byte_register(client, page, PMBUS_VOUT_MODE))
+                vout_mode = _pmbus_read_byte_data(client, page,
+                                                  PMBUS_VOUT_MODE);
         if (vout_mode >= 0 && vout_mode != 0xff) {
                 /*
                  * Not all chips support the VOUT_MODE command,
@@ -1659,7 +1661,7 @@ static int pmbus_identify_common(struct i2c_client *client,
                         if (data->info->format[PSC_VOLTAGE_OUT] != linear)
                                 return -ENODEV;
 
-                        data->exponent = ((s8)(vout_mode << 3)) >> 3;
+                        data->exponent[page] = ((s8)(vout_mode << 3)) >> 3;
                         break;
                 case 1: /* VID mode         */
                         if (data->info->format[PSC_VOLTAGE_OUT] != vid)
@@ -1674,7 +1676,7 @@ static int pmbus_identify_common(struct i2c_client *client,
                 }
         }
 
-        pmbus_clear_fault_page(client, 0);
+        pmbus_clear_fault_page(client, page);
         return 0;
 }
 
@@ -1682,7 +1684,7 @@ static int pmbus_init_common(struct i2c_client *client, struct pmbus_data *data,
                              struct pmbus_driver_info *info)
 {
         struct device *dev = &client->dev;
-        int ret;
+        int page, ret;
 
         /*
          * Some PMBus chips don't support PMBUS_STATUS_BYTE, so try
@@ -1715,10 +1717,12 @@ static int pmbus_init_common(struct i2c_client *client, struct pmbus_data *data,
                 return -ENODEV;
         }
 
-        ret = pmbus_identify_common(client, data);
-        if (ret < 0) {
-                dev_err(dev, "Failed to identify chip capabilities\n");
-                return ret;
+        for (page = 0; page < info->pages; page++) {
+                ret = pmbus_identify_common(client, data, page);
+                if (ret < 0) {
+                        dev_err(dev, "Failed to identify chip capabilities\n");
+                        return ret;
+                }
         }
         return 0;
 }