Re: [PATCH v1 3/3] ARM64 LPC: update binding doc

[Rongrong Zou]

å 2016/1/12 18:14, liviu.dudau@xxxxxxx åé:
> On Tue, Jan 12, 2016 at 05:25:56PM +0800, Rongrong Zou wrote:
> > å 2016/1/12 17:07, liviu.dudau@xxxxxxx åé:
> > > On Tue, Jan 12, 2016 at 10:39:36AM +0800, Rongrong Zou wrote:
> > > > On 2016/1/12 0:14, liviu.dudau@xxxxxxx wrote:
> > > > > On Mon, Jan 04, 2016 at 12:13:05PM +0100, Arnd Bergmann wrote:
> > > > > > On Sunday 03 January 2016 20:24:14 Rongrong Zou wrote:
> > > > > > > å 2015/12/31 23:00, Rongrong Zou åé:
> > > > > > > > 2015-12-31 22:40 GMT+08:00 Arnd Bergmann <arnd@xxxxxxxx <mailto:arnd@xxxxxxxx>>:
> > > > > > > >   > On Thursday 31 December 2015 22:12:19 Rongrong Zou wrote:
> > > > > > > >   > > å 2015/12/30 17:06, Arnd Bergmann åé:
> > > > > > > >   > > > On Tuesday 29 December 2015 21:33:52 Rongrong Zou wrote:
> > > > > > > >   >
> > > > > > > >   > The DT sample above looks good in principle. I believe what you are missing
> > > > > > > >   > here is code in your driver to scan the child nodes to create the platform
> > > > > > > >   > devices. of_bus_isa_translate() should work with your definition here
> > > > > > > >   > and create the correct IORESOURCE_IO resources. You don't have any MMIO
> > > > > > > >   > resources, so the absence of a ranges property is ok. Maybe all you
> > > > > > > >   > are missing is a call to of_platform_populate() or of_platform_bus_probe()?
> > > > > > > >   >
> > > > > > > >
> > > > > > > > You are right. thanks, i'll try on test board .  if i get the correct result , the new patch
> > > > > > > > will be sent later. By the way, it's my another email account use when i at home.
> > > > > > >
> > > > > > > I tried, and there need some additional changes.
> > > > > > >
> > > > > > > isa@a01b0000 {
> > > > > > >
> > > > > > > /*the node name should start with "isa", because of below definition
> > > > > > > * static int of_bus_isa_match(struct device_node *np)
> > > > > > > * {
> > > > > > > *	return !strcmp(np->name, "isa");
> > > > > > > * }
> > > > > >
> > > > > > Looks good. It would be nicer to match on device_type than on name,
> > > > > > but this is ancient code and it's probably best not to touch it
> > > > > > so we don't accidentally break some old SPARC or PPC system.
> > > > > >
> > > > > > > */
> > > > > > > 	compatible = "low-pin-count";
> > > > > > > 	device_type = "isa";
> > > > > > > 	#address-cells = <2>;
> > > > > > > 	#size-cells = <1>;
> > > > > > > 	reg = <0x0 0xa01b0000 0x0 0x10000>;
> > > > > > > 	ranges = <0x1 0x0 0x0 0x0 0x1000>;
> > > > > > > /*
> > > > > > > *  ranges is required, then i can get the IORESOURCE_IO <0xe4,4> from "reg = <0x1, 0x000000e4, 4>".
> > > > > > > *
> > > > > > > */
> > > > > > > 	ipmi_0:ipmi@000000e4{
> > > > > > > 		device_type = "ipmi";
> > > > > > > 		compatible = "ipmi-bt";
> > > > > > > 		reg = <0x1 0x000000e4 0x4>;
> > > > > > > };
> > > > > >
> > > > > > This looks wrong: the property above says that the I/O port range is
> > > > > > translated to MMIO address 0x00000000 to 0x00010000, which is not
> > > > > > true on your hardware. I think this needs to be changed in the code
> > > > > > so the ranges property is not required for I/O ports.
> > > > > >
> > > > > > > drivers\of\address.c
> > > > > > > static int __of_address_to_resource(struct device_node *dev,
> > > > > > >                   const __be32 *addrp, u64 size, unsigned int flags,
> > > > > > >                   const char *name, struct resource *r)
> > > > > > > {
> > > > > > >           u64 taddr;
> > > > > > >
> > > > > > >           if ((flags & (IORESOURCE_IO | IORESOURCE_MEM)) == 0)
> > > > > > >                   return -EINVAL;
> > > > > > >           taddr = of_translate_address(dev, addrp);
> > > > > > >           if (taddr == OF_BAD_ADDR)
> > > > > > >                   return -EINVAL;
> > > > > > >           memset(r, 0, sizeof(struct resource));
> > > > > > >           if (flags & IORESOURCE_IO) {
> > > > > > >                   unsigned long port;
> > > > > > >
> > > > > > > /*****************************************************************/
> > > > > > > /*legacy port(< 0x1000) is reserved, and need no translation here*/
> > > > > > > /*****************************************************************/
> > > > > > >                   if(taddr + size < PCIBIOS_MIN_IO){
> > > > > > >                           r->start = taddr;
> > > > > > >                           r->end = taddr + size - 1;
> > > > > > >                   }
> > > > > >
> > > > > > I don't like having a special case based on the address here,
> > > > > > the same kind of hack might be needed for PCI I/O spaces in
> > > > > > hardware that uses an indirect method like your LPC bus
> > > > > > does, and the code above will not work on any LPC implementation
> > > > > > that correctly multiplexes its I/O ports with the first PCI domain.
> > > > > >
> > > > > > I think it would be better to avoid translating the port into
> > > > > > a physical address to start with just to translate it back into
> > > > > > a port number, what we need instead is the offset between the
> > > > > > bus specific port number and the linux port number. I've added
> > > > > > Liviu to Cc, he wrote this code originally and may have some idea
> > > > > > of how we could do that.
> > > > >
> > > > > Hi,
> > > >
> > > > Hi Liviu,
> > > >
> > > > Thanks for reviewing this.
> > > >
> > > > > Getting back to work after a longer holiday, my brain might not be running
> > > > > at full speed here, so I'm trying to clarify things a bit here.
> > > > >
> > > > > It looks to me like Rongrong is trying to trap the inb()/outb() calls that he
> > > > > added to arm64 by patch 1/3 and redirect those operations to the memory
> > > > > mapped LPC driver. I think the whole redirection and registration of inb/outb
> > > > > ops can be made cleaner, so that the general concept resembles the DMA ops
> > > > > registration? (I have this mental picture that what Rongrong is trying to do
> > > > > is similar to what a DMA engine does, except this is slowing down things to
> > > > > byte level). If that is done properly in the parent node, then we should not
> > > > > care what the PCIBIOS_MIN_IO value is as the inb()/outb() calls will always
> > > > > go through the redirection for the children.
> > > > >
> > > > > As for the ranges property: does he wants the ipmi-bt driver to see in the
> > > > > reg property the legacy ISA I/O ports values or the CPU addresses? If the former,
> > > > > then I agree that the range property should not be required, but also the
> > > > > reg values need to be changed (drop the top bit). If the later, then the
> > > > > ranges property is required to do the proper translation.
> > > >
> > > > The former, thanks.
> > > >
> > > > > Rongrong, removing the ranges property and with a reg = <0xe4 0x4> property
> > > > > in the ipmi-bt node, what IO_RESOURCE type resources do you get back from
> > > > > the of_address_to_resource() translation?
> > > >
> > > > I want to get IORESOURCE_IO type resource, but if the parent node drop the
> > > > "rangs" property, the of_address_to_resource() translation will return with -EINVAL.
> > >
> > > Have you tracked what part of the code is sensitive to the presence of "ranges"
> > > property? Does of_get_address() call returns the IO_RESOURCE flag set without "ranges"?
> >
> >
> > Yes, IO_RESOURCE flag can be get without "ranges".
> > I tracked the code, it is at of_translate_one(), Below is the calling infomation.
> >
> > of_address_to_resource-> __of_address_to_resource ->of_translate_address->
> > __of_translate_address(dev, in_addr, "ranges")->of_translate_one()
> >
> >
> > static int of_translate_one(struct device_node *parent, struct of_bus *bus,
> > 			    struct of_bus *pbus, __be32 *addr,
> > 			    int na, int ns, int pna, const char *rprop)
> > {
> > 	const __be32 *ranges;
> > 	unsigned int rlen;
> > 	int rone;
> > 	u64 offset = OF_BAD_ADDR;
> >
> > 	ranges = of_get_property(parent, rprop, &rlen);
> > 	if (ranges == NULL && !of_empty_ranges_quirk(parent)) {
> > 		pr_debug("OF: no ranges; cannot translate\n");
> > 		return 1;
> > 	}
> > 	...
> > }
>
> OK, looking at of_translate_one() comments it looks like a missing "ranges" property is
> only accepted on PowerPC. I suggest you have an empty "ranges" property in your isa
> parent node, that will signal to the OF parsing code that the mapping is 1:1. Then have
> the IPMI node use the reg = <0x0 0xe4 4>; property values instead of reg = <0x1 0xe4 4>;

But in this condition, I still can't get the right resource type IORESOURCE_IO, I just get
the MMIO resource E4:E7. Please see the url at https://lkml.org/lkml/2016/1/5/199, the empty
ranges has been discussed.


> Best regards,
> Liviu
>
> > > Best regards,
> > > Liviu
> > >
> > > > > Best regards,
> > > > > Liviu
> > > > >
> > > > >
> > > > > > 	Arnd
> > > > Regards,
> > > > Rongrong
> > --
> > Regards,
> > Rongrong
> >
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> > linux-arm-kernel mailing list
> > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel


--
Regards,
Rongrong