hwmon: (pmbus/fsp-3y) Fix FSP-3Y YH-5151E non-compliant vout encoding

I didn't properly test the driver for YH-5151E, so it was completely
broken. Firstly, the log/real mapping was incorrect in one case.
Secondly, PMBus specifies that output voltages should be in the linear16
encoding. However, the YH-5151E is non-compliant and uses linear11.
YM-2151E isn't affected by this. Fix this by converting the values
inside the read functions. linear16 gets the exponent from the VOUT_MODE
command. The device doesn't support it, so I have to manually supply the
value for it.

Both supported devices have now been tested to report correct vout
values.

Fixes: 1734b4135a62 ("hwmon: Add driver for fsp-3y PSUs and PDUs")
Signed-off-by: Václav Kubernát <kubernat@cesnet.cz>
Link: https://lore.kernel.org/r/20210429075337.110502-1-kubernat@cesnet.cz
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

diff --git a/drivers/hwmon/pmbus/fsp-3y.c b/drivers/hwmon/pmbus/fsp-3y.c
index b177987..e248424 100644 (file)
--- a/drivers/hwmon/pmbus/fsp-3y.c
+++ b/drivers/hwmon/pmbus/fsp-3y.c
@@ -57,7 +57,7 @@ static int page_log_to_page_real(int page_log, enum chips chip)
                case YH5151E_PAGE_12V_LOG:
                        return YH5151E_PAGE_12V_REAL;
                case YH5151E_PAGE_5V_LOG:
-                       return YH5151E_PAGE_5V_LOG;
+                       return YH5151E_PAGE_5V_REAL;
                case YH5151E_PAGE_3V3_LOG:
                        return YH5151E_PAGE_3V3_REAL;
                }
@@ -103,8 +103,18 @@ static int set_page(struct i2c_client *client, int page_log)
 
 static int fsp3y_read_byte_data(struct i2c_client *client, int page, int reg)
 {
+       const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
+       struct fsp3y_data *data = to_fsp3y_data(info);
        int rv;
 
+       /*
+        * YH5151-E outputs vout in linear11. The conversion is done when
+        * reading. Here, we have to inject pmbus_core with the correct
+        * exponent (it is -6).
+        */
+       if (data->chip == yh5151e && reg == PMBUS_VOUT_MODE)
+               return 0x1A;
+
        rv = set_page(client, page);
        if (rv < 0)
                return rv;
@@ -114,6 +124,8 @@ static int fsp3y_read_byte_data(struct i2c_client *client, int page, int reg)
 
 static int fsp3y_read_word_data(struct i2c_client *client, int page, int phase, int reg)
 {
+       const struct pmbus_driver_info *info = pmbus_get_driver_info(client);
+       struct fsp3y_data *data = to_fsp3y_data(info);
        int rv;
 
        /*
@@ -144,7 +156,18 @@ static int fsp3y_read_word_data(struct i2c_client *client, int page, int phase,
        if (rv < 0)
                return rv;
 
-       return i2c_smbus_read_word_data(client, reg);
+       rv = i2c_smbus_read_word_data(client, reg);
+       if (rv < 0)
+               return rv;
+
+       /*
+        * YH-5151E is non-compliant and outputs output voltages in linear11
+        * instead of linear16.
+        */
+       if (data->chip == yh5151e && reg == PMBUS_READ_VOUT)
+               rv = sign_extend32(rv, 10) & 0xffff;
+
+       return rv;
 }
 
 static struct pmbus_driver_info fsp3y_info[] = {