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

John Garry
2018-02-26T11:56:47Z

>>>>> 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