Re: [PATCHv3] hwmon: Add tc654 driver

[Guenter Roeck]

On Mon, Oct 10, 2016 at 08:08:14PM +, Chris Packham wrote:
> On 10/11/2016 02:22 AM, Guenter Roeck wrote:
> >> +  if (val)
> >> > +data->config |= TC654_REG_CONFIG_DUTYC;
> >> > +else
> >> > +data->config &= ~TC654_REG_CONFIG_DUTYC;
> > I just realized that this won't work as intended. Problem is that you
> > only fill data->config when reading an attribute. So, if a set function
> > is called prior to reading an attribute, data->config will be 0, and
> > you end up overwriting the original configuration.
> >
> 
> Should I just read it in the probe function or fill it in with the 
> documented hardware defaults?

Reading it would be better - that leaves the option open that it was configured
by ROMMON or BIOS.

Guenter
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Re: [PATCHv3] hwmon: Add tc654 driver

[Chris Packham]

On 10/11/2016 02:22 AM, Guenter Roeck wrote:
>> +if (val)
>> > +  data->config |= TC654_REG_CONFIG_DUTYC;
>> > +  else
>> > +  data->config &= ~TC654_REG_CONFIG_DUTYC;
> I just realized that this won't work as intended. Problem is that you
> only fill data->config when reading an attribute. So, if a set function
> is called prior to reading an attribute, data->config will be 0, and
> you end up overwriting the original configuration.
>

Should I just read it in the probe function or fill it in with the 
documented hardware defaults?
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Re: [PATCHv3] hwmon: Add tc654 driver

[Guenter Roeck]

On 10/09/2016 03:12 PM, Chris Packham wrote:

Add support for the tc654 and tc655 fan controllers from Microchip.

http://ww1.microchip.com/downloads/en/DeviceDoc/20001734C.pdf

Signed-off-by: Chris Packham 
---
Changes in v3:
- typofix in documentation
- add missing value to tc654_pwm_map, re-generate based on datasheet.
- remove unnecessary hwmon_dev member from struct tc654_data
- bug fixes in set_fan_min() and show_pwm_mode()
- miscellaneous style fixes

Changes in v2:
- Add Documentation/hwmon/tc654
- Incorporate most of the review comments from Guenter. Additional error
  handling is added. Unused/unnecessary code is removed. I decided not
  to go down the regmap path yet. I may circle back to it when I look at
  using regmap in the adm9240 driver.

 .../devicetree/bindings/i2c/trivial-devices.txt|   2 +
 Documentation/hwmon/tc654  |  31 ++
 drivers/hwmon/Kconfig  |  11 +
 drivers/hwmon/Makefile |   1 +
 drivers/hwmon/tc654.c  | 509 +
 5 files changed, 554 insertions(+)
 create mode 100644 Documentation/hwmon/tc654
 create mode 100644 drivers/hwmon/tc654.c

diff --git a/Documentation/devicetree/bindings/i2c/trivial-devices.txt 
b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
index 1416c6a0d2cd..833fb9f133d3 100644
--- a/Documentation/devicetree/bindings/i2c/trivial-devices.txt
+++ b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
@@ -122,6 +122,8 @@ microchip,mcp4662-502   Microchip 8-bit Dual I2C 
Digital Potentiometer with NV Mem
 microchip,mcp4662-103  Microchip 8-bit Dual I2C Digital Potentiometer with NV 
Memory (10k)
 microchip,mcp4662-503  Microchip 8-bit Dual I2C Digital Potentiometer with NV 
Memory (50k)
 microchip,mcp4662-104  Microchip 8-bit Dual I2C Digital Potentiometer with NV 
Memory (100k)
+microchip,tc654PWM Fan Speed Controller With Fan Fault 
Detection
+microchip,tc655PWM Fan Speed Controller With Fan Fault 
Detection
 national,lm63  Temperature sensor with integrated fan control
 national,lm75  I2C TEMP SENSOR
 national,lm80  Serial Interface ACPI-Compatible Microprocessor System 
Hardware Monitor
diff --git a/Documentation/hwmon/tc654 b/Documentation/hwmon/tc654
new file mode 100644
index ..91a2843f5f98
--- /dev/null
+++ b/Documentation/hwmon/tc654
@@ -0,0 +1,31 @@
+Kernel driver tc654
+===
+
+Supported chips:
+  * Microship TC654 and TC655
+Prefix: 'tc654'
+Datasheet: http://ww1.microchip.com/downloads/en/DeviceDoc/20001734C.pdf
+
+Authors:
+Chris Packham 
+Masahiko Iwamoto 
+
+Description
+---
+This driver implements support for the Microchip TC654 and TC655.
+
+The TC654 uses the 2-wire interface compatible with the SMBUS 2.0
+specification. The TC654 has two (2) inputs for measuring fan RPM and
+one (1) PWM output which can be used for fan control.
+
+Configuration Notes
+---
+Ordinarily the pwm1_mode ABI is used for controlling the pwm output
+mode.  However, for this chip the output is always pwm, and the
+pwm1_mode determines if the pwm output is controlled via the pwm1 value
+or via the Vin analog input.
+
+
+Setting pwm1_mode to 1 will cause the pwm output to be driven based on
+the pwm1 value. Setting pwm1_mode to 0 will cause the pwm output to be
+driven based on the Vin input.
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 45cef3d2c75c..8681bc65cde5 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -907,6 +907,17 @@ config SENSORS_MCP3021
  This driver can also be built as a module.  If so, the module
  will be called mcp3021.

+config SENSORS_TC654
+   tristate "Microchip TC654/TC655 and compatibles"
+   depends on I2C
+   help
+ If you say yes here you get support for TC654 and TC655.
+ The TC654 and TC655 are PWM mode fan speed controllers with
+ FanSense technology for use with brushless DC fans.
+
+ This driver can also be built as a module.  If so, the module
+ will be called tc654.
+
 config SENSORS_MENF21BMC_HWMON
tristate "MEN 14F021P00 BMC Hardware Monitoring"
depends on MFD_MENF21BMC
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index aecf4ba17460..c651f0f1d047 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -122,6 +122,7 @@ obj-$(CONFIG_SENSORS_MAX6697)   += max6697.o
 obj-$(CONFIG_SENSORS_MAX31790) += max31790.o
 obj-$(CONFIG_SENSORS_MC13783_ADC)+= mc13783-adc.o
 obj-$(CONFIG_SENSORS_MCP3021)  += mcp3021.o
+obj-$(CONFIG_SENSORS_TC654)+= tc654.o
 obj-$(CONFIG_SENSORS_MENF21BMC_HWMON) += menf21bmc_hwmon.o
 obj-$(CONFIG_SENSORS_NCT6683)  += nct6683.o
 obj-$(CONFIG_SENSORS_NCT6775)  += nct6775.o
diff --git