[U-Boot] Device tree & PCI/ECAM questions

[Aaron Williams]

Hi Jagen,

On 11/01/2016 11:33 AM, Jagan Teki wrote:
> On Tue, Nov 1, 2016 at 6:49 AM, Aaron Williams
> <Aaron.Williams at caviumnetworks.com> wrote:
>> Hi all,
>>
>> I am working on several drivers for our Octeon-TX/Thunder chips which talk
>> to devices connected to the ECAM bus through another sub-bus and am having
>> issues regarding the device tree.
>>
>> We have a "PCI" driver to handle the ECAM and I created a simple-bus stub
>> for our MRML bus which connects low-speed devices to the ECAM bus and all of
>> the devices show up in the device tree.
>>
>> My problem is that the devices also enumerated via PCI.
>>
>> I have something like the following:
>>
>> static int cavium_pci_mmc_probe(struct udevice *dev)
>> {
>>      debug("%s: Entry\n", __func__);
>>      pci_dev_t bdf = dm_pci_get_bdf(dev);
>>      struct cavium_mmc_host *host = dev_get_priv(dev);
>>      size_t size;
>>      uint64_t base_addr = dm_pci_map_bar(dev, 0, &size, PCI_REGION_MEM);
>>      int rc = 0;
>>
>>      host->base_addr = base_addr;
>>      dev->req_seq = PCI_FUNC(bdf);
>>
>>      debug("%s(%s): ", __func__, dev->name);
>>      debug("  platdata:        %p\n"
>>            "  parent platdata: %p\n"
>>            "  uclass platdata: %p\n"
>>            "  base address:    %lx\n"
>>            "  of_offset:       %d\n"
>>            "  parent:          %p\n"
>>            "  priv:            %p\n"
>>            "  uclass:          %p\n"
>>            "  req_seq:         %d\n"
>>            "  seq:             %d\n",
>>            dev->platdata, dev->parent_platdata,
>>            dev->uclass_platdata, base_addr,
>>            dev->of_offset, dev->parent, dev->priv,
>>            dev->uclass, dev->req_seq, dev->seq);
>>
>>      if (dev->of_offset >= 0)
>>          rc = process_node(dev, gd->fdt_blob, dev->of_offset);
>>
>>      return rc;
>> }
>>
>> static const struct udevice_id cavium_mmc_ids[] = {
>>      { .compatible = "cavium,thunder-8890-mmc" },
>>      { .compatible = "cavium,mmc" },
>>      { },
>> };
>>
>> static const struct udevice_id cavium_mmc_slot_ids[] = {
>>      { .compatible = "cavium,thunder-8890-mmc-slot" },
>>      { },
>> };
>>
>> U_BOOT_DRIVER(cavium_pci_mmc) = {
>>      .name    = "mmc_cavium",
>>      .id    = UCLASS_MMC,
>>      .of_match = of_match_ptr(cavium_mmc_ids),
>>      .ofdata_to_platdata = cavium_mmc_ofdata_to_platdata,
>>      .probe    = cavium_pci_mmc_probe,
>>      .priv_auto_alloc_size = sizeof(struct cavium_mmc_host),
>>      .ops = NULL,
>> };
>>
>> static struct pci_device_id cavium_pci_mmc_supported[] = {
>>      { PCI_VDEVICE(CAVIUM, PCI_DEVICE_ID_THUNDER_MMC) },
>>      {},
>> };
>>
>> U_BOOT_PCI_DEVICE(cavium_pci_mmc, cavium_pci_mmc_supported);
> I think you're not using dt?
I'm using the dt and some of our other code uses it, though not 
specifically for the drivers. It's used for the serial interface, for 
example.
>> The problem I'm seeing is that in the probe function the of_offset field is
>> always -1. Shouldn't it resolve this information via the compatible string
>> in the device tree? How should I go about setting it up so that not only
> This look strange to me, but I am assuming PCI dev hierarchy may
> require u-boot,dm-pre-reloc on dt have you tried .flags =
> DM_FLAG_PRE_RELOC?
>
> thanks!
I think I see the problem. The problem is that we have this MRML bus 
which is a sort of PCI bridge for low-speed devices but we don't have a 
proper driver for this. When scanning the devices, they show up in the 
parent ECAM bus and not on the MRML bus so I'm guessing I need to create 
a PCI bridge driver for this.

-Aaron

-- 
Aaron Williams
Software Engineer
Cavium, Inc.
(408) 943-7198  (510) 789-8988 (cell)