[PATCH v3 2/2] hwmon: (nct6775) Fix RPM output for fan7 on NCT6796D

[Guenter Roeck <linux@roeck-us.net>]

fan7 on NCT6796D does not have a fan count register; it only has an RPM
register. Switch to using RPM registers to read the fan speed for all
chips supporting it to solve the problem for good.

Reported-by: Robert Kern <ulteq@web.de>
Cc: Robert Kern <ulteq@web.de>
Fixes: 81820059a428 ("hwmon: (nct6775) Add support for NCT6796D")
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
v3: Further minimize changes: Add new dummy function to convert register
    values into rpm
v2: NCT6795D/NCT6796D still have the old RPM registers, only the register
    at 0x660 is new and has to be used. Minimize required changes by using
    the 'old' RPM registers where possible. 

 drivers/hwmon/nct6775.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/drivers/hwmon/nct6775.c b/drivers/hwmon/nct6775.c
index 202a2b422461..af4d8792bbb5 100644
--- a/drivers/hwmon/nct6775.c
+++ b/drivers/hwmon/nct6775.c
@@ -502,7 +502,7 @@ static const s8 NCT6779_BEEP_BITS[] = {
 	30, 31 };			/* intrusion0, intrusion1 */
 
 static const u16 NCT6779_REG_FAN[] = {
-	0x4b0, 0x4b2, 0x4b4, 0x4b6, 0x4b8, 0x4ba, 0x660 };
+	0x4c0, 0x4c2, 0x4c4, 0x4c6, 0x4c8, 0x4ca, 0x660 };
 static const u16 NCT6779_REG_FAN_PULSES[NUM_FAN] = {
 	0x644, 0x645, 0x646, 0x647, 0x648, 0x649 };
 
@@ -924,6 +924,11 @@ static unsigned int fan_from_reg16(u16 reg, unsigned int divreg)
 	return 1350000U / (reg << divreg);
 }
 
+static unsigned int fan_from_reg_rpm(u16 reg, unsigned int divreg)
+{
+	return reg;
+}
+
 static u16 fan_to_reg(u32 fan, unsigned int divreg)
 {
 	if (!fan)
@@ -1284,7 +1289,7 @@ static bool is_word_sized(struct nct6775_data *data, u16 reg)
 	case nct6795:
 	case nct6796:
 		return reg == 0x150 || reg == 0x153 || reg == 0x155 ||
-		  ((reg & 0xfff0) == 0x4b0 && (reg & 0x000f) < 0x0b) ||
+		  (reg & 0xfff0) == 0x4c0 ||
 		  reg == 0x402 ||
 		  reg == 0x63a || reg == 0x63c || reg == 0x63e ||
 		  reg == 0x640 || reg == 0x642 || reg == 0x64a ||
@@ -3868,7 +3873,7 @@ static int nct6775_probe(struct platform_device *pdev)
 		data->ALARM_BITS = NCT6779_ALARM_BITS;
 		data->BEEP_BITS = NCT6779_BEEP_BITS;
 
-		data->fan_from_reg = fan_from_reg13;
+		data->fan_from_reg = fan_from_reg_rpm;
 		data->fan_from_reg_min = fan_from_reg13;
 		data->target_temp_mask = 0xff;
 		data->tolerance_mask = 0x07;
@@ -3949,7 +3954,7 @@ static int nct6775_probe(struct platform_device *pdev)
 		data->ALARM_BITS = NCT6791_ALARM_BITS;
 		data->BEEP_BITS = NCT6779_BEEP_BITS;
 
-		data->fan_from_reg = fan_from_reg13;
+		data->fan_from_reg = fan_from_reg_rpm;
 		data->fan_from_reg_min = fan_from_reg13;
 		data->target_temp_mask = 0xff;
 		data->tolerance_mask = 0x07;
-- 
2.7.4