Messages in this thread | | | Date | Tue, 22 Sep 2015 09:56:52 -0700 | From | David Daney <> | Subject | Re: [PATCH 3/3] PCI: generic: Add support for Cavium ThunderX PCIe root complexes. |
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On 09/22/2015 09:40 AM, Lorenzo Pieralisi wrote: > On Tue, Sep 22, 2015 at 05:13:45PM +0100, David Daney wrote: >> On 09/22/2015 09:05 AM, Lorenzo Pieralisi wrote: >>> On Thu, Sep 17, 2015 at 11:41:34PM +0100, David Daney wrote: > > [...] > >>>> Properties of the host controller node: >>>> >>>> -- compatible : Must be "pci-host-cam-generic" or "pci-host-ecam-generic" >>>> - depending on the layout of configuration space (CAM vs >>>> - ECAM respectively). >>>> +- compatible : One of the following with bus:devfn:reg mapped to the >>>> + PCI config space address window in the bit positions shown: >>>> + "pci-host-cam-generic" -- 'CAM' bits 16:8:0 >>>> + "pci-host-ecam-generic" -- 'ECAM' bits 20:12:0 >>>> + "cavium,pci-host-thunder-pem" -- bits 24:16:0 >>> >>> To me that's ECAM left shifted by 4. Is not it just a matter of defining >>> config space base address (ie reg property) differently ? >> >> No. >> >> That's like saying ECAM is just CAM shifted by 4, can't we just specify >> the "reg" differently. > > Ok, sorry I was not clear, apologies. I meant to ask if it is something > that can be configured in your platform and apparently it is not,
No, the hardware cannot be adjusted.
> I worded it wrongly.
OK, I guess I also misunderstood what you were suggesting.
> >> The "reg" property describes the base of the config space access window. >> CAM/ECAM/cavium,pci-host-thunder-pem describe how to generate offsets >> from that base, The offset calculation requires information that is not >> present in the "reg" property, it is enumerated in the various >> "compatible" values listed above. > > Agreed, this also forces you to map in more virtual address space for > a given bus, right ?
Yes. It takes a full 32-bits of address space to have access to all PCI buses on the root complex.
> I am also a bit worried about how we can make this > work with ACPI, where MCFG accessors take the bus and devfn shifts for > granted (ie ECAM specs), so I asked.
If ACPI is not flexible enough to describe actual hardware, it will either have to be enhanced, or not used.
> > Thanks, > Lorenzo > >> >> David Daney >> >>> >>> Lorenzo >>> >>>> >>>> - device_type : Must be "pci". >>>> >>>> diff --git a/drivers/pci/host/pci-host-generic.c b/drivers/pci/host/pci-host-generic.c >>>> index e364232..e1d8d5b 100644 >>>> --- a/drivers/pci/host/pci-host-generic.c >>>> +++ b/drivers/pci/host/pci-host-generic.c >>>> @@ -91,6 +91,32 @@ static struct gen_pci_cfg_bus_ops gen_pci_cfg_ecam_bus_ops = { >>>> } >>>> }; >>>> >>>> +static void __iomem *gen_pci_map_cfg_bus_thunder_pem(struct pci_bus *bus, >>>> + unsigned int devfn, >>>> + int where) >>>> +{ >>>> + struct gen_pci *pci = bus->sysdata; >>>> + resource_size_t idx = bus->number - pci->cfg.bus_range->start; >>>> + >>>> + /* >>>> + * Thunder PEM is a PCIe RC, but without a root bridge. On >>>> + * the primary bus, ignore accesses for devices other than >>>> + * the first device. >>>> + */ >>>> + if (idx == 0 && (devfn & ~7u)) >>>> + return NULL; >>>> + return pci->cfg.win[idx] + ((devfn << 16) | where); >>>> +} >>>> + >>>> +static struct gen_pci_cfg_bus_ops gen_pci_cfg_thunder_pem_bus_ops = { >>>> + .bus_shift = 24, >>>> + .ops = { >>>> + .map_bus = gen_pci_map_cfg_bus_thunder_pem, >>>> + .read = pci_generic_config_read, >>>> + .write = pci_generic_config_write, >>>> + } >>>> +}; >>>> + >>>> static const struct of_device_id gen_pci_of_match[] = { >>>> { .compatible = "pci-host-cam-generic", >>>> .data = &gen_pci_cfg_cam_bus_ops }, >>>> @@ -98,6 +124,9 @@ static const struct of_device_id gen_pci_of_match[] = { >>>> { .compatible = "pci-host-ecam-generic", >>>> .data = &gen_pci_cfg_ecam_bus_ops }, >>>> >>>> + { .compatible = "cavium,pci-host-thunder-pem", >>>> + .data = &gen_pci_cfg_thunder_pem_bus_ops }, >>>> + >>>> { }, >>>> }; >>>> MODULE_DEVICE_TABLE(of, gen_pci_of_match); >>>> -- >>>> 1.9.1 >>>> >>>> -- >>>> To unsubscribe from this list: send the line "unsubscribe linux-pci" in >>>> the body of a message to majordomo@vger.kernel.org >>>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>>> >>
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