Re: [RFC PATCH 0/2] serial: 8250_dw: IO space + polling mode support

[John Garry]

> > > > > Why you can't do properly in ACPI?
> > >
> > > No answer here either.
> > >
> > > Sorry, but with this level of communication it's no go for the
> > > series.
> >
> > Sorry if my answers did not tell you want you want to know.
> >
> > My point was that the 8250_pnp driver would be used for a pnp_device,
> > but we are creating a platform device for this UART slave so would
> > require a platform device driver, that which 8250_dw.c is. But I will
> > check on pnp device support.

Hi Andy,

> Perhaps it's not visible, though below is a description of the drivers
> we have:
>
> 8250_dw - OF/ACPI driver for Synopsys DW (+ DW DMA)
> 8250_lpss - PCI driver for Synopsys DW (+ DW DMA)
> 8250_of -  generic 8250 compatible driver for OF
> 8250_pci - generic 8250 compatible driver for PCI
> 8250_pnp - generic 8250 compatible driver for ACPI
>
> 8250_* (except core parts) - custom glue drivers per some IPs
>
> By description you gave your driver fits 8250_pnp if ACPI tables crafted
> properly.
>
> Share the ACPI excerpt and we can discuss further how to improve them.

For a bit of background, MFD support was discussed here initially:
https://lkml.org/lkml/2017/6/13/796

Here is the ACPI table:
Scope(_SB) {
  Device (LPC0) {
    Name (_HID, "HISI0191")  // HiSi LPC
    Name (_CRS, ResourceTemplate () {
      Memory32Fixed (ReadWrite, 0xa01b0000, 0x1000)
    })
  }

  Device (LPC0.CON0) {
    Name (_HID, "HISI1031")
    // Name (_CID, "PNP0501") // cannot support PNP
    Name (LORS, ResourceTemplate() {
      QWordIO (
        ResourceConsumer,
    MinNotFixed,     // _MIF
    MaxNotFixed,     // _MAF
    PosDecode,
    EntireRange,
    0x0,             // _GRA
    0x2F8,           // _MIN
    0x3fff,          // _MAX
    0x0,             // _TRA
    0x08,            // _LEN
    , ,
    IO02


The latest framework changes and host driver patchset are here:
https://lkml.org/lkml/2018/2/19/465

Here is how we probe the children:
static int hisi_lpc_acpi_set_io_res(struct device *child,
                    struct device *hostdev,
                    const struct resource **res,
                    int *num_res)
{

    [ ... In this part we just get the child resources ]


    /* translate the I/O resources */
    for (i = 0; i < count; i++) {
        int ret;

        if (!(resources[i].flags & IORESOURCE_IO))
            continue;
        ret = hisi_lpc_acpi_xlat_io_res(adev, host, &resources[i]);
        if (ret) {
            dev_err(child, "translate IO range failed(%d)\n", ret);
            return ret;
        }
    }
    *res = resources;
    *num_res = count;

    return 0;
}

static int hisi_lpc_acpi_probe(struct device *hostdev)
{
    struct acpi_device *adev = ACPI_COMPANION(hostdev);
    struct hisi_lpc_mfd_cell *hisi_lpc_mfd_cells;
    struct mfd_cell *mfd_cells;
    struct acpi_device *child;
    int size, ret, count = 0, cell_num = 0;

    list_for_each_entry(child, &adev->children, node)
        cell_num++;

    /* allocate the mfd cell and companion acpi info, one per child */
    size = sizeof(*mfd_cells) + sizeof(*hisi_lpc_mfd_cells);
    mfd_cells = devm_kcalloc(hostdev, cell_num, size, GFP_KERNEL);
    if (!mfd_cells)
        return -ENOMEM;

    hisi_lpc_mfd_cells = (struct hisi_lpc_mfd_cell *)
                    &mfd_cells[cell_num];
    /* Only consider the children of the host */
    list_for_each_entry(child, &adev->children, node) {
        struct mfd_cell *mfd_cell = &mfd_cells[count];
        struct hisi_lpc_mfd_cell *hisi_lpc_mfd_cell =
                    &hisi_lpc_mfd_cells[count];
        struct mfd_cell_acpi_match *acpi_match =
                    &hisi_lpc_mfd_cell->acpi_match;
        char *name = hisi_lpc_mfd_cell[count].name;
        char *pnpid = hisi_lpc_mfd_cell[count].pnpid;
        struct mfd_cell_acpi_match match = {
            .pnpid = pnpid,
        };

        snprintf(name, MFD_CHILD_NAME_LEN, MFD_CHILD_NAME_PREFIX"%s",
             acpi_device_hid(child));
        snprintf(pnpid, ACPI_ID_LEN, "%s", acpi_device_hid(child));

        memcpy(acpi_match, &match, sizeof(*acpi_match));
        mfd_cell->name = name;
        mfd_cell->acpi_match = acpi_match;

        ret = hisi_lpc_acpi_set_io_res(&child->dev, &adev->dev,
                           &mfd_cell->resources,
                           &mfd_cell->num_resources);
        if (ret) {
            dev_warn(&child->dev, "set resource fail(%d)\n", ret);
            return ret;
        }
        count++;
    }

    ret = mfd_add_devices(hostdev, PLATFORM_DEVID_NONE,
                  mfd_cells, cell_num, NULL, 0, NULL);
    if (ret) {
        dev_err(hostdev, "failed to add mfd cells (%d)\n", ret);
        return ret;
    }

    return 0;
}

As you know, this is not accepted upstream yet, but I really hope I'm 
close. Hence the RFC tag for the UART patchset.

Please let me know if you require more details.

Thanks,
John