[v3,1/2] dt-bindings: hwmon: add tmp464.yaml

From: Agathe Porte <agathe.porte@nokia.com>

Add basic description of the tmp464 driver DT bindings.

Signed-off-by: Agathe Porte <agathe.porte@nokia.com>
Cc: Krzysztof Adamski <krzysztof.adamski@nokia.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
Note:
  I had previously asked to add more detailed bindings, but concluded
  that those should be provided in a generic temperature sensor schema.
  I'll try to introduce such a schema separately.

v3:
- Addedd support for TMP468.
- Changed number of channels from 0..3 (which was wrong anyway) to 0..8.
- Changed value range for ti,n-factor to int8, with an example for
  a negative value.
- Added myself as driver maintainer.

 .../devicetree/bindings/hwmon/ti,tmp464.yaml  | 109 ++++++++++++++++++
 MAINTAINERS                                   |   7 ++
 2 files changed, 116 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/hwmon/ti,tmp464.yaml

Hi Guenter,

Le 16/02/2022 à 08:07, Guenter Roeck a écrit :
> Add support for Texas Instruments TMP464 and TMP468 temperature sensor
> ICs.
>
> TI's TMP464 is an I2C temperature sensor chip. This chip is
> similar to TI's TMP421 chip, but with 16bit-wide registers (instead
> of 8bit-wide registers). The chip has one local sensor and four
> remote sensors. TMP468 is similar to TMP464 but has one local and
> eight remote sensors.
>
> Originally-from: Agathe Porte <agathe.porte@nokia.com>
> Cc: Agathe Porte <agathe.porte@nokia.com>
> Cc: Krzysztof Adamski <krzysztof.adamski@nokia.com>
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
> ---
> v3:
> - Added support for TMP468
> - Added support for various limits, temperature hysteresis, alarm attributes,
>    and update interval
> - Use regmap instead of local caching
> - Use static chip configuration
> - Unlock check if needed when loading driver, and lock it when unloading it
>    - Call tmp464_init_client() before calling tmp464_probe_from_dt()
>      since the latter changes registers, which requires the chip to be
>      unlocked.
> - Restore configuration register when unloading driver
> - ti,n-factor is optional, so don't fail if the property is not present
>
> Notes:
> - Tested with real TMP468. Module tested for TMP464.
> - I was not able to test with a system supporting devicetree;
>    especially negative values for "ti,n-factor" need testing
>    (and I wonder if of_property_read_s8() would be needed to
>     support this properly).

I just did the test on our system and both positive and negative value 
n-factor fails.

With the following overlay:

/dts-v1/;
/plugin/;
/ {
         fragment@0 {
                 target-path = "/soc/.../i2c@4/tmp464@49";
                 __overlay__ {
                         #address-cells = <1>;
                         #size-cells = <0>;

                         channel@0 {
                                 reg = <0x0>;
                                 label = "local";
                                 ti,n-factor = /bits/ 8 <(-10)>;
                         };

                         channel@1 {
                                 reg = <0x1>;
                                 label = "ch1";
                         };

                         channel@2 {
                                 reg = <0x2>;
                                 label = "ch2";
                         };

                         channel@3 {
                                 reg = <0x3>;
                                 label = "ch3";
                         };

                         channel@4 {
                                 reg = <0x4>;
                                 label = "ch4";
                         };
                 };
         };

};

I get the following probing error:

[ 3580.557425] tmp464: probe of 16-0049 failed with error -75

With a positive n-factor in the overlay (<(10)> instead of <(-10)>), the 
driver *does not load either*, with the same error message.

Without any n-factor set, the v3 driver you proposed loads just fine 
with the DT.

Any idea of where this could come from? This was probably not working in 
my own implementation either.

PS: check your spam folder eventually for my mail asking delivery 
details of the TMP464 samples.

Bests,

Agathe.

On 2/16/22 04:42, Agathe Porte wrote:
> Hi Guenter,
> 
> Le 16/02/2022 à 08:07, Guenter Roeck a écrit :
>> Add support for Texas Instruments TMP464 and TMP468 temperature sensor
>> ICs.
>>
>> TI's TMP464 is an I2C temperature sensor chip. This chip is
>> similar to TI's TMP421 chip, but with 16bit-wide registers (instead
>> of 8bit-wide registers). The chip has one local sensor and four
>> remote sensors. TMP468 is similar to TMP464 but has one local and
>> eight remote sensors.
>>
>> Originally-from: Agathe Porte <agathe.porte@nokia.com>
>> Cc: Agathe Porte <agathe.porte@nokia.com>
>> Cc: Krzysztof Adamski <krzysztof.adamski@nokia.com>
>> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
>> ---
>> v3:
>> - Added support for TMP468
>> - Added support for various limits, temperature hysteresis, alarm attributes,
>>    and update interval
>> - Use regmap instead of local caching
>> - Use static chip configuration
>> - Unlock check if needed when loading driver, and lock it when unloading it
>>    - Call tmp464_init_client() before calling tmp464_probe_from_dt()
>>      since the latter changes registers, which requires the chip to be
>>      unlocked.
>> - Restore configuration register when unloading driver
>> - ti,n-factor is optional, so don't fail if the property is not present
>>
>> Notes:
>> - Tested with real TMP468. Module tested for TMP464.
>> - I was not able to test with a system supporting devicetree;
>>    especially negative values for "ti,n-factor" need testing
>>    (and I wonder if of_property_read_s8() would be needed to
>>     support this properly).
> 
> I just did the test on our system and both positive and negative value n-factor fails.
> 
> With the following overlay:
> 
> /dts-v1/;
> /plugin/;
> / {
>          fragment@0 {
>                  target-path = "/soc/.../i2c@4/tmp464@49";
>                  __overlay__ {
>                          #address-cells = <1>;
>                          #size-cells = <0>;
> 
>                          channel@0 {
>                                  reg = <0x0>;
>                                  label = "local";
>                                  ti,n-factor = /bits/ 8 <(-10)>;
>                          };
> 
>                          channel@1 {
>                                  reg = <0x1>;
>                                  label = "ch1";
>                          };
> 
>                          channel@2 {
>                                  reg = <0x2>;
>                                  label = "ch2";
>                          };
> 
>                          channel@3 {
>                                  reg = <0x3>;
>                                  label = "ch3";
>                          };
> 
>                          channel@4 {
>                                  reg = <0x4>;
>                                  label = "ch4";
>                          };
>                  };
>          };
> 
> };
> 
> I get the following probing error:
> 
> [ 3580.557425] tmp464: probe of 16-0049 failed with error -75
> 

I think that may be caused by using of_property_read_s32() for reading
an 8-bit property. Can you try and replace of_property_read_s32()
with of_property_read_u8() and the variable it points to to s8 ?

	s8 val;
	...
	err = of_property_read_u8(child, "ti,n-factor", &val);

There is no of_property_read_s8(), so we can not use that,
but maybe using of_property_read_u8() does the trick.

Thanks,
Guenter

> With a positive n-factor in the overlay (<(10)> instead of <(-10)>), the driver *does not load either*, with the same error message.
> 
> Without any n-factor set, the v3 driver you proposed loads just fine with the DT.
> 
> Any idea of where this could come from? This was probably not working in my own implementation either.
> 
> PS: check your spam folder eventually for my mail asking delivery details of the TMP464 samples.
> 
> Bests,
> 
> Agathe.
>