Re: [rfc]pwm: add BCM2835 PWM driver

[Bart Tanghe]

Is it the responsibility of the pwm driver to handle the pinmux of the 
io pins? Or is the end user, or a parent driver responsible to handle this?
Idem for the clock?


On 04/09/2014 05:59 PM, Tim Kryger wrote:
> On Tue, Apr 8, 2014 at 6:27 PM, Stephen Warren <swarren@xxxxxxxxxxxxx> wrote:
> > On 04/08/2014 05:02 PM, Tim Kryger wrote:
> > > On Thu, Apr 3, 2014 at 6:44 AM, Bart Tanghe <bart.tanghe@xxxxxxxxxxxxx> wrote:
> > > > need some recommendation
> > > > the memory mapped io registers of the bcm2835 pwm hardware are spreaded
> > > > over the memory mapped io
> > > > gpio config 0x20200004 - clk config 0x201010A0 - pwm configuration 0x2020C000
> > > > to handle this, I've used the base address of the memory mapped io
> > > > so I can use positive offsets
> > > So the registers for this PWM are located in three distinct memory regions?
> > ...
> > > > +struct bcm2835_pwm_chip {
> > > > +       struct pwm_chip chip;
> > > > +       struct device *dev;
> > > > +       int channel;
> > > > +       void __iomem *mmio;
> > > One pointer isn't going to be enough.  You need three.
> > >
> > > I suggest renaming the first and adding two more:
> > >
> > > void __iomem *base_pwm;
> > > void __iomem *base_clk;
> > > void __iomem *base_alt;
> > Sorry, I forgot about this patch. One comment here; the PWM driver can't
> > touch the clock or alt registers; those should be owned by the clock
> > driver, and the driver for whatever alt is (pinmux - don't recall what
> > it's touching there).
> Absolutely.  If these registers are owned by other drivers, go through them.

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