Re: [PATCH] SB600 for the Nemo board has non-zero devices on non-root bus

[Bjorn Helgaas <helgaas@kernel.org>]

On Fri, Dec 15, 2017 at 09:04:51AM +0100, Christian Zigotzky wrote:
> On 09 December 2017 at 7:03PM, Christian Zigotzky wrote:
> > On 08 December 2017 at 12:59PM, Michael Ellerman wrote:
> > >
> > >> Darren's idea of doing it at the same time you tweak the SB600 "relax
> > >> pci-e" bit is ideal because then the two pieces are obviously
> > >> connected and it wouldn't affect any other systems at all.
> > >
> > > Yes that would be ideal. That patch is currently out-of-tree I gather,
> > > but I guess everyone who's using these machines must have that patch
> > > anyway.
> > >
> > > Darren what does that code look like? Can we get it upstream and close
> > > the loop on this?
> > >
> > > cheers
> > >
> >
> > Hi Michael,
> >
> > Please find attached the code.
> >
> > Thanks,
> > Christian
> 
> Hi All,
> 
> I haven't received any response yet. Is this the correct patch you
> are looking for?

This is a powerpc patch that doesn't affect the PCI core, so I would
say this is Michael's bailiwick.

I guess you're only looking for a hint about whether this is the right
approach, because it's obviously fully baked yet (no changelog,
signed-off-by, etc, not a "safe for all powerpc" run-time solution,
not in Linux indentation style, etc).

It looks like the "pasemi,1682m-iob" DT property is required and
possibly sufficient to identify this system at run-time.

My advice is to finish that stuff up, post it to the powerpc
maintainers and the linuxppc-dev@lists.ozlabs.org list, and go from
there.

> diff -rupN a/arch/powerpc/platforms/pasemi/pci.c b/arch/powerpc/platforms/pasemi/pci.c
> --- a/arch/powerpc/platforms/pasemi/pci.c	2017-11-16 08:18:35.078874462 +0100
> +++ b/arch/powerpc/platforms/pasemi/pci.c	2017-11-16 08:17:22.034367975 +0100
> @@ -27,6 +27,7 @@
>  #include <linux/pci.h>
>  
>  #include <asm/pci-bridge.h>
> +#include <asm/isa-bridge.h>
>  #include <asm/machdep.h>
>  
>  #include <asm/ppc-pci.h>
> @@ -108,6 +109,69 @@ static int workaround_5945(struct pci_bu
>  	return 1;
>  }
>  
> +#ifdef CONFIG_PPC_PASEMI_NEMO
> +static int sb600_bus = 5;
> +static void __iomem *iob_mapbase = NULL;
> +
> +static int pa_pxp_read_config(struct pci_bus *bus, unsigned int devfn,
> +                             int offset, int len, u32 *val);
> +
> +static void sb600_set_flag(int bus)
> +{
> +    struct resource res;
> +    struct device_node *dn;
> +       struct pci_bus *busp;
> +       u32 val;
> +       int err;
> +
> +       if (sb600_bus == -1)
> +       {
> +               busp = pci_find_bus(0, 0);
> +               pa_pxp_read_config(busp, PCI_DEVFN(17,0), PCI_SECONDARY_BUS, 1, &val);
> +
> +               sb600_bus = val;
> +
> +               printk(KERN_CRIT "NEMO SB600 on bus %d.\n",sb600_bus);
> +       }
> +
> +       if (iob_mapbase == NULL)
> +       {
> +        dn = of_find_compatible_node(NULL, "isa", "pasemi,1682m-iob");
> +        if (!dn)
> +        {
> +               printk(KERN_CRIT "NEMO SB600 missing iob node\n");
> +                       return;
> +               }
> +
> +               err = of_address_to_resource(dn, 0, &res);
> +        of_node_put(dn);
> +
> +               if (err)
> +               {
> +               printk(KERN_CRIT "NEMO SB600 missing resource\n");
> +                       return;
> +               }
> +
> +               printk(KERN_CRIT "NEMO SB600 IOB base %08lx\n",res.start);
> +
> +               iob_mapbase = ioremap(res.start + 0x100, 0x94);
> +       }
> +
> +       if (iob_mapbase != NULL)
> +       {
> +               if (bus == sb600_bus)
> +               {
> +                       out_le32(iob_mapbase + 4, in_le32(iob_mapbase + 4) | 0x800);
> +               }
> +               else
> +               {
> +                       out_le32(iob_mapbase + 4, in_le32(iob_mapbase + 4) & ~0x800);
> +               }
> +       }
> +}
> +#endif
> +
> +
>  static int pa_pxp_read_config(struct pci_bus *bus, unsigned int devfn,
>  			      int offset, int len, u32 *val)
>  {
> @@ -126,6 +190,10 @@ static int pa_pxp_read_config(struct pci
>  
>  	addr = pa_pxp_cfg_addr(hose, bus->number, devfn, offset);
>  
> +#ifdef CONFIG_PPC_PASEMI_NEMO
> +       sb600_set_flag(bus->number);
> +#endif
> +
>  	/*
>  	 * Note: the caller has already checked that offset is
>  	 * suitably aligned and that len is 1, 2 or 4.
> @@ -210,6 +278,9 @@ static int __init pas_add_bridge(struct
>  	/* Interpret the "ranges" property */
>  	pci_process_bridge_OF_ranges(hose, dev, 1);
>  
> +	/* Scan for an isa bridge. */
> +	isa_bridge_find_early(hose);
> +
>  	return 0;
>  }