Subject: [PATCH 1/2] iio: mxs: Add MX23 support into the IIO driver

From: [email-masked] (Marek Vasut)
Date: Mon, 21 Jan 2013 22:49:10 +0100

Dear Lars-Peter Clausen,

> On 01/21/2013 10:32 PM, Marek Vasut wrote:
> > Dear Micha? Miros?aw,
> > 
> >> 2013/1/21 Marek Vasut <[email-masked]>:
> >>> Dear Micha? Miros?aw,
> >>> 
> >>>> 2013/1/21 Marek Vasut <[email-masked]>:
> >>>>> This patch adds support for i.MX23 into the LRADC driver. The LRADC
> >>>>> block on MX23 is not much different from the one on MX28, thus this
> >>>>> is only a few changes fixing the parts that are specific to MX23.
> >>>> 
> >>>> [...]
> >>>> 
> >>>>> +struct mxs_lradc_of_config {
> >>>>> +       const int               irq_count;
> >>>>> +       const char * const      *irq_name;
> >>>>> +};
> >>>>> +
> >>>>> +static const struct mxs_lradc_of_config const mxs_lradc_of_config[]
> >>>>> = { +       [IMX23_LRADC] = {
> >>>>> +               .irq_count      = ARRAY_SIZE(mx23_lradc_irq_names),
> >>>>> +               .irq_name       = mx23_lradc_irq_names,
> >>>>> +       },
> >>>>> +       [IMX28_LRADC] = {
> >>>>> +               .irq_count      = ARRAY_SIZE(mx28_lradc_irq_names),
> >>>>> +               .irq_name       = mx28_lradc_irq_names,
> >>>>> +       },
> >>>>> +};
> >>>>> +
> >>>>> 
> >>>>>  enum mxs_lradc_ts {
> >>>>>  
> >>>>>         MXS_LRADC_TOUCHSCREEN_NONE = 0,
> >>>>>         MXS_LRADC_TOUCHSCREEN_4WIRE,
> >>>>> 
> >>>>> @@ -857,8 +890,19 @@ static void mxs_lradc_hw_stop(struct mxs_lradc
> >>>>> *lradc)
> >>>>> 
> >>>>>                 writel(0, lradc->base + LRADC_DELAY(i));
> >>>>>  
> >>>>>  }
> >>>>> 
> >>>>> +static const struct of_device_id mxs_lradc_dt_ids[] = {
> >>>>> +       { .compatible = "fsl,imx23-lradc", .data = (void
> >>>>> *)IMX23_LRADC, }, +       { .compatible = "fsl,imx28-lradc", .data =
> >>>>> (void
> >>>>> *)IMX28_LRADC, }, +       { /* sentinel */ }
> >>>>> +};
> >>>>> +MODULE_DEVICE_TABLE(of, mxs_lradc_dt_ids);
> >>>>> +
> >>>> 
> >>>> Why not s/(void \*)\(IMX.._LRADC\)/\&mxs_lradc_of_config[\1]/ ?
> >>> 
> >>> Check the register layout, it differs between MX23 and MX28, that's one
> >>> reason, since were we to access differently placed registers, we can do
> >>> it easily as in the SSP/I2C drivers.
> >>> 
> >>> Moreover, there are some features on the MX28 that are not on the MX23
> >>> (like voltage treshold triggers and touchbuttons), with this setup, we
> >>> can easily check what we're running at at runtime and determine to
> >>> disallow these.
> >>> 
> >>> From my point of view, using the number (IMX23_LRADC / IMX28_LRADC) is
> >>> much more convenient in the long run.
> >> 
> >> I'm asking, because you don't use this number anywhere other than in
> >> mxs_lradc_probe()
> >> and there only to dereference the irq-names table. After that the
> >> structure and number
> >> are forgotten.
> > 
> > Certainly, so far it's used only this way. But please see my argument
> > about register layout, that's why I went down this road of abstraction.
> 
> You'll probably be better of by putting these differences into the
> mxs_lradc_of_config struct as well, instead of adding switch statements
> here and there throughout the code.

Certainly. All that is needed is in place now.

Best regards,
Marek Vasut