hwmon: add support for GMT G751 chip in lm75 driver

This was tested on a NETGEAR ReadyNAS 2120 device (Marvell Armada XP based board, via DT).

---
Hi Guenter,

As a side note, I removed the hunk that was present in previous patch to add gmt to the list of DT vendor prefixes because I noticed someone had taken care: https://lkml.org/lkml/2013/9/12/365

For the records, here is what I get on my NAS with the attached patch:

root@thin:/sys# sensors
g762-i2c-0-3e
Adapter: mv64xxx_i2c adapter
fan1:        5461 RPM  (div = 1)

g762-i2c-0-48
Adapter: mv64xxx_i2c adapter
fan1: 5461 RPM (div = 1)

g762-i2c-0-49
Adapter: mv64xxx_i2c adapter
fan1: 5461 RPM (div = 1)

g751-i2c-0-4c
Adapter: mv64xxx_i2c adapter
temp1: +30.5°C (high = +80.0°C, hyst = +75.0°C)

armada_thermal-virtual-0
Adapter: Virtual device
temp1: +34.2°C

root@thin:/sys/bus/i2c/drivers/lm75/0-004c# ls
driver  modalias  subsystem    temp1_max       uevent
hwmon   name      temp1_input  temp1_max_hyst

root@thin:/sys/bus/i2c/drivers/lm75/0-004c# dmesg | grep lm
[  120.960471] lm75 0-004c: hwmon3: sensor 'g751'

just by adding the following to the .dts:

	g751: g751@4c {
		compatible = "gmt,g751";
		reg = <0x4c>;
	};

Do not hesitate to tell me if I missed something.

Cheers,

a+

 Documentation/devicetree/bindings/i2c/trivial-devices.txt | 1 +
 drivers/hwmon/Kconfig                                     | 1 +
 drivers/hwmon/lm75.c                                      | 3 +++
 3 files changed, 5 insertions(+)

index ad6a738..c98e5a2 100644
@@ -35,6 +35,7 @@ fsl,mc13892		MC13892: Power Management Integrated Circuit (PMIC) for i.MX35/51
 fsl,mma8450		MMA8450Q: Xtrinsic Low-power, 3-axis Xtrinsic Accelerometer
 fsl,mpr121		MPR121: Proximity Capacitive Touch Sensor Controller
 fsl,sgtl5000		SGTL5000: Ultra Low-Power Audio Codec
+gmt,g751		G751: Digital Temperature Sensor and Thermal Watchdog with Two-Wire Interface
 infineon,slb9635tt	Infineon SLB9635 (Soft-) I2C TPM (old protocol, max 100khz)
 infineon,slb9645tt	Infineon SLB9645 I2C TPM (new protocol, max 400khz)
 maxim,ds1050		5 Bit Programmable, Pulse-Width Modulator

index b3ab9d4..52d548f 100644
@@ -656,6 +656,7 @@ config SENSORS_LM75
 
 		- Analog Devices ADT75
 		- Dallas Semiconductor DS75, DS1775 and DS7505
+		- Global Mixed-mode Technology (GMT) G751
 		- Maxim MAX6625 and MAX6626
 		- Microchip MCP980x
 		- National Semiconductor LM75, LM75A

index c03b490..7e3ef13 100644
@@ -39,6 +39,7 @@ enum lm75_type {		/* keep sorted in alphabetical order */
 	ds1775,
 	ds75,
 	ds7505,
+	g751,
 	lm75,
 	lm75a,
 	max6625,

@@ -208,6 +209,7 @@ lm75_probe(struct i2c_client *client, const struct i2c_device_id *id)
 		data->resolution = 12;
 		data->sample_time = HZ / 4;
 		break;
+	case g751:
 	case lm75:
 	case lm75a:
 		data->resolution = 9;

@@ -296,6 +298,7 @@ static const struct i2c_device_id lm75_ids[] = {
 	{ "ds1775", ds1775, },
 	{ "ds75", ds75, },
 	{ "ds7505", ds7505, },
+	{ "g751", g751, },
 	{ "lm75", lm75, },
 	{ "lm75a", lm75a, },
 	{ "max6625", max6625, },

1.8.4.rc3

Looks good. I'll apply it to my -next branch. Since I already sent my pull request to Linus, this will only go in after -rc1, which I hope should be ok (unless Jean wants to pick it up for his pull request).

Those rpms are pretty high. Are the fans all really running that fast ?

Thanks,
Guenter

Hi Guenter,

Perfect, thanks.

Unlike the fans on NETGEAR ReadyNAS 102 and 104 which are Protechnic MGT9212YB-025 92mmx92mm running at 3200 RPM max, the three fans in the RN2120 are Protechnic MGT4012XB-O20, i.e. 40mmx40mm running at 8000 RPM max. At least, this is the max RPM value I found on their website (Search Products on left side of http://www.protechnic-us.com/en/) for both devices.

When pushing one a bit, here is the max rotation speed I get:

 root@thin:/sys/bus/i2c/drivers/g762/0-003e# echo 9000 > fan1_target ; \
                                             sleep 5 ; cat fan1_input
 8057

which AFAICT validates current settings for G762 and fan combination. Did I miss something?

Cheers,

a+

No, I don't.

Jean Delvare