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

liviu.dudau
2016-01-12T15:13:40Z

On Tue, Jan 12, 2016 at 07:56:47PM +0800, Rongrong Zou wrote:
> 在 2016/1/12 19:27, liviu.dudau@arm.com 写道:
> >On Tue, Jan 12, 2016 at 07:05:29PM +0800, Rongrong Zou wrote:
> >>在 2016/1/12 18:14, liviu.dudau@arm.com 写道:
> >>>On Tue, Jan 12, 2016 at 05:25:56PM +0800, Rongrong Zou wrote:
> >>>>在 2016/1/12 17:07, liviu.dudau@arm.com 写道:
> >>>>>On Tue, Jan 12, 2016 at 10:39:36AM +0800, Rongrong Zou wrote:
> >>>>>>On 2016/1/12 0:14, liviu.dudau@arm.com 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:
> >>>>>>>>>在 2015/12/31 23:00, Rongrong Zou 写道:
> >>>>>>>>>>2015-12-31 22:40 GMT+08:00 Arnd Bergmann <arnd@arndb.de <mailto:arnd@arndb.de>>:
> >>>>>>>>>> > On Thursday 31 December 2015 22:12:19 Rongrong Zou wrote:
> >>>>>>>>>> > > 在 2015/12/30 17:06, Arnd Bergmann 写道:
> >>>>>>>>>> > > > 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".
> >
> >Earlier, you said this ^
> >
> >>>>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.
> >
> >So, when you use an empty "ranges" of_get_address() doesn't return the right flags? What resource
> >do you actually get, MMIO is not a valid value.
>
>
>
> I'm sorry I did not describe clearly.
> Without "ranges", of_get_address() will return with valid value, but of_address_to_resource()
> will return with -EINVAL;
>
> int of_address_to_resource(struct device_node *dev, int index,
> struct resource *r)
> {
> ...
> /* flags can be get here, without ranges property reqired.
> * if the reg = <0x0 0xe4 4>, I can get flag of IORESOURCE_MEM,
> * if the reg = <0x1 0xe4 4>, I can get flag of IORESOURCE_IO,

That is strange, the parent node has #address-cells = <2> so the first two numbers should be part
of the address and not influence the flags. Can you add some debugging in of_get_address() and
try to figure out what bus is used in *flags = bus->get_flags(prop) ?

> */
> addrp = of_get_address(dev, index, &size, &flags);
>
> if (addrp == NULL)
> return -EINVAL;
>
> /* Get optional "reg-names" property to add a name to a resource */
> of_property_read_string_index(dev, "reg-names", index, &name);
>
>
> /* If it is empty ranges, and the flag is IORESOURCE_MEM then the below __of_address_to_resource return with valid addr,
> * if it is empty ranges, and the flag is IORESOURCE_IO then return with -EINVAL, because
> * pci_address_to_pio() will be called when flag is IORESOURCE_IO.
> * if the ranges is absent, then return with -EINVAL.
> */
> return __of_address_to_resource(dev, addrp, size, flags, name, r);
> }
>
> I want to get resource with flag = IORESOURCE_IO, resource.start=0XE4, resource.size=0X4,

Yes, that is what I expect you should get as well.

Liviu

>
> >
> >Liviu
> >
> >>
> >>--
> >>Regards,
> >>Rongrong
> >>
> >
>
>
> --
> Regards,
> Rongrong
>

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