IIO Driver for TMP117 Temperature sensor

IIO Driver for TMP117 Temperature sensor

[Puranjay Mohan]

I have this TI's TMP117 sensor with me and I was thinking about writing an
IIO driver for it as a hobby project. Is the IIO subsystem the correct
place for this driver? if yes, can someone help me get started with this,
I haven't written an IIO driver before. I have this sensor and also a
raspberry pi with me for testing.

-- 
Thanks and Regards

Yours Truly,

Puranjay Mohan

Re: IIO Driver for TMP117 Temperature sensor

[Alexandru Ardelean]

On Tue, Dec 8, 2020 at 6:10 PM Puranjay Mohan <puranjay12@gmail.com> wrote:
>
> I have this TI's TMP117 sensor with me and I was thinking about writing an
> IIO driver for it as a hobby project. Is the IIO subsystem the correct
> place for this driver? if yes, can someone help me get started with this,
> I haven't written an IIO driver before. I have this sensor and also a
> raspberry pi with me for testing.

This could also fit into drivers/hwmon.
Looking at the HWMON subsystem there are more TMP drivers there
(TMP102/103/108/401/513).
The first 3 seem a bit more similar to TMP117 (in terms of register map).

Let's see what others have to add.
But, all-in-all whatever driver you end up writing, the easiest method
is to copy an existing similar driver and extend it.
Sometimes, a part can be added to an existing driver.
At a quick scan through existing drivers, it doesn't look like TMP117
is similar to existing drivers, so it may require a new driver
altogether.
I may have missed something though.

Thanks
Alex

>
> --
> Thanks and Regards
>
> Yours Truly,
>
> Puranjay Mohan

Re: IIO Driver for TMP117 Temperature sensor

[Guenter Roeck]

On 12/9/20 12:11 AM, Alexandru Ardelean wrote:
> On Tue, Dec 8, 2020 at 6:10 PM Puranjay Mohan <puranjay12@gmail.com> wrote:
>>
>> I have this TI's TMP117 sensor with me and I was thinking about writing an
>> IIO driver for it as a hobby project. Is the IIO subsystem the correct
>> place for this driver? if yes, can someone help me get started with this,
>> I haven't written an IIO driver before. I have this sensor and also a
>> raspberry pi with me for testing.
> 
> This could also fit into drivers/hwmon.
> Looking at the HWMON subsystem there are more TMP drivers there
> (TMP102/103/108/401/513).
> The first 3 seem a bit more similar to TMP117 (in terms of register map).
> 

It would probably be better suited for hwmon (it has limit registers,
suggesting a common use as hardware monitoring device).

> Let's see what others have to add.
> But, all-in-all whatever driver you end up writing, the easiest method
> is to copy an existing similar driver and extend it.
> Sometimes, a part can be added to an existing driver.
> At a quick scan through existing drivers, it doesn't look like TMP117
> is similar to existing drivers, so it may require a new driver
> altogether.

I don't see an immediate match either, but the tmp102 hwmon driver
might be a good start.

Guenter

> I may have missed something though.
> 
> Thanks
> Alex
> 
>>
>> --
>> Thanks and Regards
>>
>> Yours Truly,
>>
>> Puranjay Mohan

Re: IIO Driver for TMP117 Temperature sensor

[Jonathan Cameron]

On Wed, 9 Dec 2020 11:48:40 -0800
Guenter Roeck <linux@roeck-us.net> wrote:

> On 12/9/20 12:11 AM, Alexandru Ardelean wrote:
> > On Tue, Dec 8, 2020 at 6:10 PM Puranjay Mohan <puranjay12@gmail.com> wrote:  
> >>
> >> I have this TI's TMP117 sensor with me and I was thinking about writing an
> >> IIO driver for it as a hobby project. Is the IIO subsystem the correct
> >> place for this driver? if yes, can someone help me get started with this,
> >> I haven't written an IIO driver before. I have this sensor and also a
> >> raspberry pi with me for testing.  
> > 
> > This could also fit into drivers/hwmon.
> > Looking at the HWMON subsystem there are more TMP drivers there
> > (TMP102/103/108/401/513).
> > The first 3 seem a bit more similar to TMP117 (in terms of register map).
> >   
> 
> It would probably be better suited for hwmon (it has limit registers,
> suggesting a common use as hardware monitoring device).
It is a curious part.  I suspect TI based their design for a medical grade
digital thermometer chip on an existing hwmon part.

The limit registers are very simple so could be supported by IIO.
This sits somewhere in the middle of high end thermocouple chips which
tend to be in IIO and typically lower accuracy / range hwmon parts.

It's in the fuzzy borderline region so I doubt anyone would raise strong
objections to which subsystem it was in.  Guenter has fallen on the
hwmon side of things and I'm fine with that.

Jonathan

> 
> > Let's see what others have to add.
> > But, all-in-all whatever driver you end up writing, the easiest method
> > is to copy an existing similar driver and extend it.
> > Sometimes, a part can be added to an existing driver.
> > At a quick scan through existing drivers, it doesn't look like TMP117
> > is similar to existing drivers, so it may require a new driver
> > altogether.  
> 
> I don't see an immediate match either, but the tmp102 hwmon driver
> might be a good start.
> 
> Guenter
> 
> > I may have missed something though.
> > 
> > Thanks
> > Alex
> >   
> >>
> >> --
> >> Thanks and Regards
> >>
> >> Yours Truly,
> >>
> >> Puranjay Mohan  
> 

Re: IIO Driver for TMP117 Temperature sensor

[Guenter Roeck]

On 12/13/20 7:12 AM, Jonathan Cameron wrote:
> On Wed, 9 Dec 2020 11:48:40 -0800
> Guenter Roeck <linux@roeck-us.net> wrote:
> 
>> On 12/9/20 12:11 AM, Alexandru Ardelean wrote:
>>> On Tue, Dec 8, 2020 at 6:10 PM Puranjay Mohan <puranjay12@gmail.com> wrote:  
>>>>
>>>> I have this TI's TMP117 sensor with me and I was thinking about writing an
>>>> IIO driver for it as a hobby project. Is the IIO subsystem the correct
>>>> place for this driver? if yes, can someone help me get started with this,
>>>> I haven't written an IIO driver before. I have this sensor and also a
>>>> raspberry pi with me for testing.  
>>>
>>> This could also fit into drivers/hwmon.
>>> Looking at the HWMON subsystem there are more TMP drivers there
>>> (TMP102/103/108/401/513).
>>> The first 3 seem a bit more similar to TMP117 (in terms of register map).
>>>   
>>
>> It would probably be better suited for hwmon (it has limit registers,
>> suggesting a common use as hardware monitoring device).
> It is a curious part.  I suspect TI based their design for a medical grade
> digital thermometer chip on an existing hwmon part.
> 
> The limit registers are very simple so could be supported by IIO.
> This sits somewhere in the middle of high end thermocouple chips which
> tend to be in IIO and typically lower accuracy / range hwmon parts.
> 
> It's in the fuzzy borderline region so I doubt anyone would raise strong
> objections to which subsystem it was in.  Guenter has fallen on the
> hwmon side of things and I'm fine with that.
> 

On the other side, it turns out that there is already tmp107 support
in iio, and tmp107 is pretty much the spi equivalent of the same chip.
So it really depends on the use case. If the user wants to use the iio
subsystem, I am fine with it. We just need to remind people that this
implies no or only limited hwmon support.

[ I really need to spend the time to write a hwmon->iio bridge.
  The iio->hwmon bridge is a bit limited - I have not been able to
  figure out how to support limit registers (or event values)
  and events, and I don't think it is possible. ]

Guenter

> Jonathan
> 
>>
>>> Let's see what others have to add.
>>> But, all-in-all whatever driver you end up writing, the easiest method
>>> is to copy an existing similar driver and extend it.
>>> Sometimes, a part can be added to an existing driver.
>>> At a quick scan through existing drivers, it doesn't look like TMP117
>>> is similar to existing drivers, so it may require a new driver
>>> altogether.  
>>
>> I don't see an immediate match either, but the tmp102 hwmon driver
>> might be a good start.
>>
>> Guenter
>>
>>> I may have missed something though.
>>>
>>> Thanks
>>> Alex
>>>   
>>>>
>>>> --
>>>> Thanks and Regards
>>>>
>>>> Yours Truly,
>>>>
>>>> Puranjay Mohan  
>>
> 

Re: IIO Driver for TMP117 Temperature sensor

[Jonathan Cameron]

On Sun, 13 Dec 2020 08:08:26 -0800
Guenter Roeck <linux@roeck-us.net> wrote:

> On 12/13/20 7:12 AM, Jonathan Cameron wrote:
> > On Wed, 9 Dec 2020 11:48:40 -0800
> > Guenter Roeck <linux@roeck-us.net> wrote:
> >   
> >> On 12/9/20 12:11 AM, Alexandru Ardelean wrote:  
> >>> On Tue, Dec 8, 2020 at 6:10 PM Puranjay Mohan <puranjay12@gmail.com> wrote:    
> >>>>
> >>>> I have this TI's TMP117 sensor with me and I was thinking about writing an
> >>>> IIO driver for it as a hobby project. Is the IIO subsystem the correct
> >>>> place for this driver? if yes, can someone help me get started with this,
> >>>> I haven't written an IIO driver before. I have this sensor and also a
> >>>> raspberry pi with me for testing.    
> >>>
> >>> This could also fit into drivers/hwmon.
> >>> Looking at the HWMON subsystem there are more TMP drivers there
> >>> (TMP102/103/108/401/513).
> >>> The first 3 seem a bit more similar to TMP117 (in terms of register map).
> >>>     
> >>
> >> It would probably be better suited for hwmon (it has limit registers,
> >> suggesting a common use as hardware monitoring device).  
> > It is a curious part.  I suspect TI based their design for a medical grade
> > digital thermometer chip on an existing hwmon part.
> > 
> > The limit registers are very simple so could be supported by IIO.
> > This sits somewhere in the middle of high end thermocouple chips which
> > tend to be in IIO and typically lower accuracy / range hwmon parts.
> > 
> > It's in the fuzzy borderline region so I doubt anyone would raise strong
> > objections to which subsystem it was in.  Guenter has fallen on the
> > hwmon side of things and I'm fine with that.
> >   
> 
> On the other side, it turns out that there is already tmp107 support
> in iio, and tmp107 is pretty much the spi equivalent of the same chip.
> So it really depends on the use case. If the user wants to use the iio
> subsystem, I am fine with it. We just need to remind people that this
> implies no or only limited hwmon support.
> 
> [ I really need to spend the time to write a hwmon->iio bridge.
>   The iio->hwmon bridge is a bit limited - I have not been able to
>   figure out how to support limit registers (or event values)
>   and events, and I don't think it is possible. ]

So far IIO doesn't have an in kernel consumer interface for
events. It shouldn't be that hard to add one though and it 
has been on the todo list for a very long time.  We've discussed
it a few times and concluded that there are some short cuts such
as sending all events to all consumers and relying on the receiver
to do any necessary filtering. It's a bit messy but it makes for
much simpler core code.

Maybe I'll get bored enough over xmas to look at it...

Jonathan

> 
> Guenter
> 
> > Jonathan
> >   
> >>  
> >>> Let's see what others have to add.
> >>> But, all-in-all whatever driver you end up writing, the easiest method
> >>> is to copy an existing similar driver and extend it.
> >>> Sometimes, a part can be added to an existing driver.
> >>> At a quick scan through existing drivers, it doesn't look like TMP117
> >>> is similar to existing drivers, so it may require a new driver
> >>> altogether.    
> >>
> >> I don't see an immediate match either, but the tmp102 hwmon driver
> >> might be a good start.
> >>
> >> Guenter
> >>  
> >>> I may have missed something though.
> >>>
> >>> Thanks
> >>> Alex
> >>>     
> >>>>
> >>>> --
> >>>> Thanks and Regards
> >>>>
> >>>> Yours Truly,
> >>>>
> >>>> Puranjay Mohan    
> >>  
> >   
> 

Re: IIO Driver for TMP117 Temperature sensor

[Puranjay Mohan]

On Sun, Dec 13, 2020 at 9:38 PM Guenter Roeck <linux@roeck-us.net> wrote:
>
> On 12/13/20 7:12 AM, Jonathan Cameron wrote:
> > On Wed, 9 Dec 2020 11:48:40 -0800
> > Guenter Roeck <linux@roeck-us.net> wrote:
> >
> >> On 12/9/20 12:11 AM, Alexandru Ardelean wrote:
> >>> On Tue, Dec 8, 2020 at 6:10 PM Puranjay Mohan <puranjay12@gmail.com> wrote:
> >>>>
> >>>> I have this TI's TMP117 sensor with me and I was thinking about writing an
> >>>> IIO driver for it as a hobby project. Is the IIO subsystem the correct
> >>>> place for this driver? if yes, can someone help me get started with this,
> >>>> I haven't written an IIO driver before. I have this sensor and also a
> >>>> raspberry pi with me for testing.
> >>>
> >>> This could also fit into drivers/hwmon.
> >>> Looking at the HWMON subsystem there are more TMP drivers there
> >>> (TMP102/103/108/401/513).
> >>> The first 3 seem a bit more similar to TMP117 (in terms of register map).
> >>>
> >>
> >> It would probably be better suited for hwmon (it has limit registers,
> >> suggesting a common use as hardware monitoring device).
> > It is a curious part.  I suspect TI based their design for a medical grade
> > digital thermometer chip on an existing hwmon part.
> >
> > The limit registers are very simple so could be supported by IIO.
> > This sits somewhere in the middle of high end thermocouple chips which
> > tend to be in IIO and typically lower accuracy / range hwmon parts.
> >
> > It's in the fuzzy borderline region so I doubt anyone would raise strong
> > objections to which subsystem it was in.  Guenter has fallen on the
> > hwmon side of things and I'm fine with that.
> >
>
> On the other side, it turns out that there is already tmp107 support
> in iio, and tmp107 is pretty much the spi equivalent of the same chip.

Yes, you are right, tmp107 is very similar to tmp117, but it is less accurate
and it doesn't include the OFFSET functionality. Actually, I had seen the
tmp107 register in IIO and thought that tmp117 should go in IIO,
hence, I wrote this email.

So, is it fine if I write the IIO driver for this sensor? Actually,
this will just
be a hobby project for me so It doesn't bother me if it goes in hwmon or IIO.

> So it really depends on the use case. If the user wants to use the iio
> subsystem, I am fine with it. We just need to remind people that this
> implies no or only limited hwmon support.
>
> [ I really need to spend the time to write a hwmon->iio bridge.
>   The iio->hwmon bridge is a bit limited - I have not been able to
>   figure out how to support limit registers (or event values)
>   and events, and I don't think it is possible. ]
>
> Guenter
>
> > Jonathan
> >
> >>
> >>> Let's see what others have to add.
> >>> But, all-in-all whatever driver you end up writing, the easiest method
> >>> is to copy an existing similar driver and extend it.
> >>> Sometimes, a part can be added to an existing driver.
> >>> At a quick scan through existing drivers, it doesn't look like TMP117
> >>> is similar to existing drivers, so it may require a new driver
> >>> altogether.
> >>
> >> I don't see an immediate match either, but the tmp102 hwmon driver
> >> might be a good start.
> >>
> >> Guenter
> >>
> >>> I may have missed something though.
> >>>
> >>> Thanks
> >>> Alex
> >>>
> >>>>
> >>>> --
> >>>> Thanks and Regards
> >>>>
> >>>> Yours Truly,
> >>>>
> >>>> Puranjay Mohan
> >>
> >
>


-- 
Thanks and Regards

Yours Truly,

Puranjay Mohan

Re: IIO Driver for TMP117 Temperature sensor

[Puranjay Mohan]

On Sun, Dec 13, 2020 at 10:20 PM Jonathan Cameron <jic23@kernel.org> wrote:
>
> On Sun, 13 Dec 2020 08:08:26 -0800
> Guenter Roeck <linux@roeck-us.net> wrote:
>
> > On 12/13/20 7:12 AM, Jonathan Cameron wrote:
> > > On Wed, 9 Dec 2020 11:48:40 -0800
> > > Guenter Roeck <linux@roeck-us.net> wrote:
> > >
> > >> On 12/9/20 12:11 AM, Alexandru Ardelean wrote:
> > >>> On Tue, Dec 8, 2020 at 6:10 PM Puranjay Mohan <puranjay12@gmail.com> wrote:
> > >>>>
> > >>>> I have this TI's TMP117 sensor with me and I was thinking about writing an
> > >>>> IIO driver for it as a hobby project. Is the IIO subsystem the correct
> > >>>> place for this driver? if yes, can someone help me get started with this,
> > >>>> I haven't written an IIO driver before. I have this sensor and also a
> > >>>> raspberry pi with me for testing.
> > >>>
> > >>> This could also fit into drivers/hwmon.
> > >>> Looking at the HWMON subsystem there are more TMP drivers there
> > >>> (TMP102/103/108/401/513).
> > >>> The first 3 seem a bit more similar to TMP117 (in terms of register map).
> > >>>
> > >>
> > >> It would probably be better suited for hwmon (it has limit registers,
> > >> suggesting a common use as hardware monitoring device).
> > > It is a curious part.  I suspect TI based their design for a medical grade
> > > digital thermometer chip on an existing hwmon part.
> > >
> > > The limit registers are very simple so could be supported by IIO.
> > > This sits somewhere in the middle of high end thermocouple chips which
> > > tend to be in IIO and typically lower accuracy / range hwmon parts.
> > >
> > > It's in the fuzzy borderline region so I doubt anyone would raise strong
> > > objections to which subsystem it was in.  Guenter has fallen on the
> > > hwmon side of things and I'm fine with that.
> > >
> >
> > On the other side, it turns out that there is already tmp107 support
> > in iio, and tmp107 is pretty much the spi equivalent of the same chip.
> > So it really depends on the use case. If the user wants to use the iio
> > subsystem, I am fine with it. We just need to remind people that this
> > implies no or only limited hwmon support.
> >
> > [ I really need to spend the time to write a hwmon->iio bridge.
> >   The iio->hwmon bridge is a bit limited - I have not been able to
> >   figure out how to support limit registers (or event values)
> >   and events, and I don't think it is possible. ]
>
> So far IIO doesn't have an in kernel consumer interface for
> events. It shouldn't be that hard to add one though and it
> has been on the todo list for a very long time.  We've discussed
> it a few times and concluded that there are some short cuts such
> as sending all events to all consumers and relying on the receiver
> to do any necessary filtering. It's a bit messy but it makes for
> much simpler core code.
>
> Maybe I'll get bored enough over xmas to look at it...
>

Hi Jonathan,
Where can I access this TODO list, I would like to do some tasks on it.
I am a novice but I might be able to solve the easier tasks.

> Jonathan
>
> >
> > Guenter
> >
> > > Jonathan
> > >
> > >>
> > >>> Let's see what others have to add.
> > >>> But, all-in-all whatever driver you end up writing, the easiest method
> > >>> is to copy an existing similar driver and extend it.
> > >>> Sometimes, a part can be added to an existing driver.
> > >>> At a quick scan through existing drivers, it doesn't look like TMP117
> > >>> is similar to existing drivers, so it may require a new driver
> > >>> altogether.
> > >>
> > >> I don't see an immediate match either, but the tmp102 hwmon driver
> > >> might be a good start.
> > >>
> > >> Guenter
> > >>
> > >>> I may have missed something though.
> > >>>
> > >>> Thanks
> > >>> Alex
> > >>>
> > >>>>
> > >>>> --
> > >>>> Thanks and Regards
> > >>>>
> > >>>> Yours Truly,
> > >>>>
> > >>>> Puranjay Mohan
> > >>
> > >
> >
>


-- 
Thanks and Regards

Yours Truly,

Puranjay Mohan

Re: IIO Driver for TMP117 Temperature sensor

[Jonathan Cameron]

On Mon, 14 Dec 2020 01:44:20 +0530
Puranjay Mohan <puranjay12@gmail.com> wrote:

> On Sun, Dec 13, 2020 at 10:20 PM Jonathan Cameron <jic23@kernel.org> wrote:
> >
> > On Sun, 13 Dec 2020 08:08:26 -0800
> > Guenter Roeck <linux@roeck-us.net> wrote:
> >  
> > > On 12/13/20 7:12 AM, Jonathan Cameron wrote:  
> > > > On Wed, 9 Dec 2020 11:48:40 -0800
> > > > Guenter Roeck <linux@roeck-us.net> wrote:
> > > >  
> > > >> On 12/9/20 12:11 AM, Alexandru Ardelean wrote:  
> > > >>> On Tue, Dec 8, 2020 at 6:10 PM Puranjay Mohan <puranjay12@gmail.com> wrote:  
> > > >>>>
> > > >>>> I have this TI's TMP117 sensor with me and I was thinking about writing an
> > > >>>> IIO driver for it as a hobby project. Is the IIO subsystem the correct
> > > >>>> place for this driver? if yes, can someone help me get started with this,
> > > >>>> I haven't written an IIO driver before. I have this sensor and also a
> > > >>>> raspberry pi with me for testing.  
> > > >>>
> > > >>> This could also fit into drivers/hwmon.
> > > >>> Looking at the HWMON subsystem there are more TMP drivers there
> > > >>> (TMP102/103/108/401/513).
> > > >>> The first 3 seem a bit more similar to TMP117 (in terms of register map).
> > > >>>  
> > > >>
> > > >> It would probably be better suited for hwmon (it has limit registers,
> > > >> suggesting a common use as hardware monitoring device).  
> > > > It is a curious part.  I suspect TI based their design for a medical grade
> > > > digital thermometer chip on an existing hwmon part.
> > > >
> > > > The limit registers are very simple so could be supported by IIO.
> > > > This sits somewhere in the middle of high end thermocouple chips which
> > > > tend to be in IIO and typically lower accuracy / range hwmon parts.
> > > >
> > > > It's in the fuzzy borderline region so I doubt anyone would raise strong
> > > > objections to which subsystem it was in.  Guenter has fallen on the
> > > > hwmon side of things and I'm fine with that.
> > > >  
> > >
> > > On the other side, it turns out that there is already tmp107 support
> > > in iio, and tmp107 is pretty much the spi equivalent of the same chip.
> > > So it really depends on the use case. If the user wants to use the iio
> > > subsystem, I am fine with it. We just need to remind people that this
> > > implies no or only limited hwmon support.
> > >
> > > [ I really need to spend the time to write a hwmon->iio bridge.
> > >   The iio->hwmon bridge is a bit limited - I have not been able to
> > >   figure out how to support limit registers (or event values)
> > >   and events, and I don't think it is possible. ]  
> >
> > So far IIO doesn't have an in kernel consumer interface for
> > events. It shouldn't be that hard to add one though and it
> > has been on the todo list for a very long time.  We've discussed
> > it a few times and concluded that there are some short cuts such
> > as sending all events to all consumers and relying on the receiver
> > to do any necessary filtering. It's a bit messy but it makes for
> > much simpler core code.
> >
> > Maybe I'll get bored enough over xmas to look at it...
> >  
> 
> Hi Jonathan,
> Where can I access this TODO list, I would like to do some tasks on it.
> I am a novice but I might be able to solve the easier tasks.

Sadly I'm rubbish at keeping an up to date list.  So this tends
to be scattered across numerous ancient discussions.

I do occasionally send out such a document, though I haven't done
so for some time.  I'll see if I can do a refresh sometime in next
month or so.

Thanks,

Jonathan

> 
> > Jonathan
> >  
> > >
> > > Guenter
> > >  
> > > > Jonathan
> > > >  
> > > >>  
> > > >>> Let's see what others have to add.
> > > >>> But, all-in-all whatever driver you end up writing, the easiest method
> > > >>> is to copy an existing similar driver and extend it.
> > > >>> Sometimes, a part can be added to an existing driver.
> > > >>> At a quick scan through existing drivers, it doesn't look like TMP117
> > > >>> is similar to existing drivers, so it may require a new driver
> > > >>> altogether.  
> > > >>
> > > >> I don't see an immediate match either, but the tmp102 hwmon driver
> > > >> might be a good start.
> > > >>
> > > >> Guenter
> > > >>  
> > > >>> I may have missed something though.
> > > >>>
> > > >>> Thanks
> > > >>> Alex
> > > >>>  
> > > >>>>
> > > >>>> --
> > > >>>> Thanks and Regards
> > > >>>>
> > > >>>> Yours Truly,
> > > >>>>
> > > >>>> Puranjay Mohan  
> > > >>  
> > > >  
> > >  
> >  
> 
> 

Re: IIO Driver for TMP117 Temperature sensor

[Jonathan Cameron]

On Mon, 14 Dec 2020 01:40:32 +0530
Puranjay Mohan <puranjay12@gmail.com> wrote:

> On Sun, Dec 13, 2020 at 9:38 PM Guenter Roeck <linux@roeck-us.net> wrote:
> >
> > On 12/13/20 7:12 AM, Jonathan Cameron wrote:  
> > > On Wed, 9 Dec 2020 11:48:40 -0800
> > > Guenter Roeck <linux@roeck-us.net> wrote:
> > >  
> > >> On 12/9/20 12:11 AM, Alexandru Ardelean wrote:  
> > >>> On Tue, Dec 8, 2020 at 6:10 PM Puranjay Mohan <puranjay12@gmail.com> wrote:  
> > >>>>
> > >>>> I have this TI's TMP117 sensor with me and I was thinking about writing an
> > >>>> IIO driver for it as a hobby project. Is the IIO subsystem the correct
> > >>>> place for this driver? if yes, can someone help me get started with this,
> > >>>> I haven't written an IIO driver before. I have this sensor and also a
> > >>>> raspberry pi with me for testing.  
> > >>>
> > >>> This could also fit into drivers/hwmon.
> > >>> Looking at the HWMON subsystem there are more TMP drivers there
> > >>> (TMP102/103/108/401/513).
> > >>> The first 3 seem a bit more similar to TMP117 (in terms of register map).
> > >>>  
> > >>
> > >> It would probably be better suited for hwmon (it has limit registers,
> > >> suggesting a common use as hardware monitoring device).  
> > > It is a curious part.  I suspect TI based their design for a medical grade
> > > digital thermometer chip on an existing hwmon part.
> > >
> > > The limit registers are very simple so could be supported by IIO.
> > > This sits somewhere in the middle of high end thermocouple chips which
> > > tend to be in IIO and typically lower accuracy / range hwmon parts.
> > >
> > > It's in the fuzzy borderline region so I doubt anyone would raise strong
> > > objections to which subsystem it was in.  Guenter has fallen on the
> > > hwmon side of things and I'm fine with that.
> > >  
> >
> > On the other side, it turns out that there is already tmp107 support
> > in iio, and tmp107 is pretty much the spi equivalent of the same chip.  
> 
> Yes, you are right, tmp107 is very similar to tmp117, but it is less accurate
> and it doesn't include the OFFSET functionality. Actually, I had seen the
> tmp107 register in IIO and thought that tmp117 should go in IIO,
> hence, I wrote this email.
> 
> So, is it fine if I write the IIO driver for this sensor? Actually,
> this will just
> be a hobby project for me so It doesn't bother me if it goes in hwmon or IIO.

Sounds good to me.

Jonathan


> 
> > So it really depends on the use case. If the user wants to use the iio
> > subsystem, I am fine with it. We just need to remind people that this
> > implies no or only limited hwmon support.
> >
> > [ I really need to spend the time to write a hwmon->iio bridge.
> >   The iio->hwmon bridge is a bit limited - I have not been able to
> >   figure out how to support limit registers (or event values)
> >   and events, and I don't think it is possible. ]
> >
> > Guenter
> >  
> > > Jonathan
> > >  
> > >>  
> > >>> Let's see what others have to add.
> > >>> But, all-in-all whatever driver you end up writing, the easiest method
> > >>> is to copy an existing similar driver and extend it.
> > >>> Sometimes, a part can be added to an existing driver.
> > >>> At a quick scan through existing drivers, it doesn't look like TMP117
> > >>> is similar to existing drivers, so it may require a new driver
> > >>> altogether.  
> > >>
> > >> I don't see an immediate match either, but the tmp102 hwmon driver
> > >> might be a good start.
> > >>
> > >> Guenter
> > >>  
> > >>> I may have missed something though.
> > >>>
> > >>> Thanks
> > >>> Alex
> > >>>  
> > >>>>
> > >>>> --
> > >>>> Thanks and Regards
> > >>>>
> > >>>> Yours Truly,
> > >>>>
> > >>>> Puranjay Mohan  
> > >>  
> > >  
> >  
> 
>