Re: [PATCH v2 2/2] pwm: add this patch to support the new pwm of Rockchip SoCs

[Thierry Reding <thierry.reding@gmail.com>]

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On Sat, Jul 26, 2014 at 09:59:35PM -0700, Doug Anderson wrote:
> caesar,
> 
> On Fri, Jul 25, 2014 at 3:29 AM, caesar <caesar.wang@rock-chips.com> wrote:
> > Hi Thierry,
> >
> >
> >
> >
> > 在 2014年07月21日 21:27, Thierry Reding 写道:
> >>
> >> On Mon, Jul 21, 2014 at 08:58:42PM +0800, caesar wrote:
> >>
> >>> 于 2014年07月21日 16:50, Thierry Reding 写道:
> >>>>
> >>>> On Sat, Jul 19, 2014 at 08:55:29PM +0800, Caesar Wang wrote:
> >>
> >> [...]
> >>>>>
> >>>>>         struct rockchip_pwm_chip *pc;
> >>>>>         struct resource *r;
> >>>>>         int ret;
> >>>>> @@ -119,7 +182,10 @@ static int rockchip_pwm_probe(struct
> >>>>> platform_device *pdev)
> >>>>>                 return -ENOMEM;
> >>>>>         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> >>>>> -       pc->base = devm_ioremap_resource(&pdev->dev, r);
> >>>>> +       if (!strcmp(of_id->compatible, "rockchip,vop-pwm"))
> >>>>> +               pc->base = devm_ioremap(&pdev->dev, r->start,
> >>>>> resource_size(r));
> >>>>> +       else
> >>>>> +               pc->base = devm_ioremap_resource(&pdev->dev, r);
> >>>>
> >>>> Sorry, this still isn't an option. You really shouldn't remap I/O
> >>>> regions that other drivers may be using. You hinted at a shared register
> >>>> space during the review of the initial version. Can you provide more
> >>>> detail about what exactly the memory map looks like of the rk3288? Is
> >>>> there some kind of technical reference manual that I could look at? Or
> >>>> do you have a device tree extract that shows what the memory map looks
> >>>> like?
> >>>>
> >>>> Thierry
> >>>
> >>> Maybe,you can look at the ARM: dts: rk3288:
> >>>
> >>> https://github.com/rkchrome/kernel/blob/master/arch/arm/boot/dts/rk3288.dtsi
> >>> There is some lcdc and vop-pwm map address for rk3288.
> >>>
> >>> ,and you can look at the vop-introduce.pdf and vop-register.pdf in Annex.
> >>>
> >>> Maybe,I should put the vop-pwm in lcdc driver,but I don't hope do so it.
> >>>
> >>> Could you give a suggestion to solve it? Thanks.
> >>
> >> It looks like you could turn the lcdc device into an MFD device so that
> >> it can instantiate two devices, one for the display controller, the
> >> other for the PWM. Or perhaps it would even work with only a single
> >> child device.
> >>
> >> The device tree would become something like this:
> >>
> >>         lcdc@ff930000 {
> >>                 compatible = "rockchip,rk3288-lcdc";
> >>                 ...
> >>
> >>                 pwm@ff9301a0 {
> >>                         compatible = "rockchip,vop-pwm";
> >>                         ...
> >>                 };
> >>         };
> >>
> >> And your driver would do something like:
> >>
> >>         static const struct resource pwm_resources[] = {
> >>                 {
> >>                         .start = 0x1a0,
> >>                         .end = 0x1af,
> >>                         .flags = IORESOURCE_MEM,
> >>                 },
> >>         };
> >>
> >>         static const struct mfd_cell subdevices[] = {
> >>                 {
> >>                         .name = "pwm",
> >>                         .id = 1,
> >>                         .of_compatible = "rockchip,vop-pwm",
> >>                         .num_resources = ARRAY_SIZE(pwm_resources),
> >>                         .resources = pwm_resources,
> >>                 },
> >>         };
> >>
> >>         static int lcdc_probe(struct platform_device *pdev)
> >>         {
> >>                 struct resource *regs;
> >>                 ...
> >>
> >>                 regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> >>
> >>                 ...
> >>
> >>                 err = mfd_add_devices(&pdev->dev, 0, subdevices,
> >> ARRAY_SIZE(subdevices),
> >>                                       regs, NULL, NULL);
> >>                 ...
> >>         }
> >>
> >> Thierry
> >
> > Sorry,I might a little trouble for the changes.
> >
> > The driver changes only for lcdc? If that is the case,I suddenly don't know
> > how to do it ?
> >
> > Maybe,I didn't say it clearly.
> >
> > lcdc0: lcdc@ff930000                   |     vop0pwm: pwm@ff9301a0
> > reg = <0xff930000 0x10000>     |      reg = <0xff9301a0 0x10>;
> >
> > The lcdc has to add resource's address  from  0xff930000 to 0xff93ffff.
> >
> > When the  pwm driver is loading vop0pwm. the "devm_ioremap_resource()" will
> > be used in probe();
> >
> > I think it will be occur a fail. because the resource [mem
> > 0xff9301a0-0xff9301af] has be requested by lcdc.
> > =>rockchip-pwm ff9301a0.pwm: can't request region for resource [mem
> > 0xff9301a0-0xff9301af]
> >
> > If I do the changes in pwm driver,do you have a other suggestion for it?
> > thanks.:-)
> 
> Sorry if this is stupid (and I haven't tried it), but does "ranges"
> help solve this problem?  AKA:
> 
>          lcdc@ff930000 {
>                  compatible = "rockchip,rk3288-lcdc";
>                  reg = <0xff930000 0x10000>;
>                  #address-cells = <2>;
>                  #size-cells = <1>;
>                  ranges = <0 0xff9301a0 0x10>;
>                  ...
> 
>                  pwm@0,0 {
>                          compatible = "rockchip,vop-pwm";
>                          reg = <0 0 0x10>;
>                         ...
>                  };
>          };
> 
> Does that avoid the failure?  The lcdc driver would need to call
> of_platform_populate() to make the PWM show up.

If you add "simple-bus" to the lcdc compatible string, like so:

	lcdc@ff930000 {
		compatible = "rockchip,rk3288-lcdc", "simple-bus";
		...
	};

Then of_platform_populate() will be called automatically.

Thierry

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