On Sun, Mar 12, 2017 at 10:57:43AM -0700, Guenter Roeck wrote:
> On 03/12/2017 07:47 AM, Sam Povilus wrote:
> > Adding the ability for the ads7828 and ads7830 to use the device tree to
> > get their optional parameters, instead of using platform devices. This
> > allows people using custom boards to also use the ads7828 in a non-default
> > manner.
> >
> > Also adding a note to the user if they misconfigure the device's external
> > reference.
> >
> > v2: conforming to coding style
> > v3: changing from "_" to "-" for device tree entries
> > Signed-off-by: Sam Povilus <kernel.development@xxxxxxxx>
> > ---
> > Documentation/devicetree/bindings/hwmon/ads7828.txt | 18 ++++++++++++++++++
> > .../devicetree/bindings/i2c/trivial-devices.txt | 2 --
> > drivers/hwmon/ads7828.c | 15 +++++++++++++++
> > 3 files changed, 33 insertions(+), 2 deletions(-)
> > create mode 100644 Documentation/devicetree/bindings/hwmon/ads7828.txt
> >
> > diff --git a/Documentation/devicetree/bindings/hwmon/ads7828.txt b/Documentation/devicetree/bindings/hwmon/ads7828.txt
> > new file mode 100644
> > index 000000000000..0d37cd3fd31b
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/hwmon/ads7828.txt
> > @@ -0,0 +1,18 @@
> > +ads7828 properties
> > +
> > +Required properties:
> > +- compatible:
> > + Should be one of
> > + ti,ads7828
> > + ti,ads7830
> > +- reg: I2C address
> > +
> > +Optional properties:
> > +
> > +- diff-input
> > + Set to use the device in differential mode.
>
> I'll wait for Rob to comment, but "differential-input" sounds better to me,
> Also, it would have to have a "ti," prefix.
>
The platform device uses diff_input, are we going for consistancy or
correctness? I am good with either.
> > +- ext-vref
> > + Set to enable the external voltage reference on the device.
> > +- vref-mv
> > + The external reference on the device is set to this as an unsigned integer in
> > + milivolts. Must use "ext_vref" for this to have any meaning.
>
> ext_vref, though as suggested below I think it would be better to use a standard
> property. Also, it seems to me that ext-vref is really unnecessary; the presence
> of "vref" can imply that the reference voltage is external.
>
I agree, but again, the platform device seperates it. Consistancy or
correctness?
> > diff --git a/Documentation/devicetree/bindings/i2c/trivial-devices.txt b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
> > index cdd7b48826c3..87648909f6ce 100644
> > --- a/Documentation/devicetree/bindings/i2c/trivial-devices.txt
> > +++ b/Documentation/devicetree/bindings/i2c/trivial-devices.txt
> > @@ -163,8 +163,6 @@ st,m41t00 Serial real-time clock (RTC)
> > st,m41t62 Serial real-time clock (RTC) with alarm
> > st,m41t80 M41T80 - SERIAL ACCESS RTC WITH ALARMS
> > taos,tsl2550 Ambient Light Sensor with SMBUS/Two Wire Serial Interface
> > -ti,ads7828 8-Channels, 12-bit ADC
> > -ti,ads7830 8-Channels, 8-bit ADC
> > ti,tsc2003 I2C Touch-Screen Controller
> > ti,tmp102 Low Power Digital Temperature Sensor with SMBUS/Two Wire Serial Interface
> > ti,tmp103 Low Power Digital Temperature Sensor with SMBUS/Two Wire Serial Interface
> > diff --git a/drivers/hwmon/ads7828.c b/drivers/hwmon/ads7828.c
> > index ee396ff167d9..d1f7ba5d7a2b 100644
> > --- a/drivers/hwmon/ads7828.c
> > +++ b/drivers/hwmon/ads7828.c
> > @@ -118,6 +118,7 @@ static int ads7828_probe(struct i2c_client *client,
> > struct ads7828_data *data;
> > struct device *hwmon_dev;
> > unsigned int vref_mv = ADS7828_INT_VREF_MV;
> > + unsigned int vref_mv_tmp;
> > bool diff_input = false;
> > bool ext_vref = false;
> > unsigned int regval;
> > @@ -131,11 +132,25 @@ static int ads7828_probe(struct i2c_client *client,
> > ext_vref = pdata->ext_vref;
> > if (ext_vref && pdata->vref_mv)
> > vref_mv = pdata->vref_mv;
> > + } else if (dev->of_node) {
> > + if (of_get_property(dev->of_node, "diff-input", NULL))
> > + diff_input = true;
> > + if (of_get_property(dev->of_node, "ext-vref", NULL))
> > + ext_vref = true;
> > + if (!of_property_read_u32(dev->of_node, "vref-mv", &vref_mv_tmp)
> > + && ext_vref)
> > + vref_mv = vref_mv_tmp;
>
> Please consider using devm_regulator_get_optional() and thus standard properties.
>
I'd have to disagree with this, but not strongly. In my reading of
Documentation/power/regulator/overview.txt it seems like the regulator
subsystem is exclusivly for regulators not for references. I would hope
that most board designers would not use a regulator, and especially not
a switch mode regulator for the input to a reference. Am I reading the
regulator subsystem overview wrong? or are people using it for things
that it's not quite intended (I will admit it looks like a number of
other adcs use it)? or is there some other explination.
> > }
> >
> > /* Bound Vref with min/max values */
> > + vref_mv_tmp = vref_mv;
> > vref_mv = clamp_val(vref_mv, ADS7828_EXT_VREF_MV_MIN,
> > ADS7828_EXT_VREF_MV_MAX);
> > + if (vref_mv_tmp != vref_mv) {
> > + pr_info("You used and invalid external vref,"
> > + " it has been clamped to %u",
> > + vref_mv);
> > + }
>
> This is an unrelated change.
>
> >
> > /* ADS7828 uses 12-bit samples, while ADS7830 is 8-bit */
> > if (id->driver_data == ads7828) {
> >
>
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