Re: [PATCH v15 8/9] HISI LPC: Add ACPI support

[Andy Shevchenko]

On Tue, 2018-02-27 at 00:40 +0800, John Garry wrote:
> Based on the previous patches, this patch supports the
> LPC host on hip06/hip07 for ACPI FW.
> 
> It is the responsibility of the LPC host driver to
> enumerate the child devices, as the ACPI scan code will
> not enumerate children of "indirect IO" hosts.
> 
> The ACPI table for the LPC host controller and the child
> devices is in the following format:
>   Device (LPC0) {
>     Name (_HID, "HISI0191")  // HiSi LPC
>     Name (_CRS, ResourceTemplate () {
>       Memory32Fixed (ReadWrite, 0xa01b0000, 0x1000)
>     })
>   }
> 
>   Device (LPC0.IPMI) {
>     Name (_HID, "IPI0001")
>     Name (LORS, ResourceTemplate() {
>       QWordIO (
>         ResourceConsumer,
> 	MinNotFixed,     // _MIF
> 	MaxNotFixed,     // _MAF
> 	PosDecode,
> 	EntireRange,
> 	0x0,             // _GRA
> 	0xe4,            // _MIN
> 	0x3fff,          // _MAX
> 	0x0,             // _TRA
> 	0x04,            // _LEN
> 	, ,
> 	BTIO
>       )
>     })
> 
> Since the IO resources of the child devices need to be
> translated from LPC bus addresses to logical PIO addresses,
> and we shouldn't modify the resources of the devices
> generated in the FW scan, a per-child MFD is created as
> a substitute. The MFD IO resources will be the translated
> bus addresses of the ACPI child.

Ok, this needs to be thought about a bit more.

I guess I understand what's is the problem with PNP IDs in the driver.

You probe your LPC device quite late.
One option is to move from classical probe to a event-driven model, i.e.
via registering a notifier (see acpi_lpss.c), preparing necessary stuff
at earlier stages and then register devices by their enumeration and
appearance.

Though, if I would be you I would seek a opinion from Rafael and Mika
(maybe others as well).

See also some comments below.

> +#ifdef CONFIG_ACPI
> +#define MFD_CHILD_NAME_PREFIX DRV_NAME"-"

> +#define MFD_CHILD_NAME_LEN (ACPI_ID_LEN +
> sizeof(MFD_CHILD_NAME_PREFIX))

..._PREFIX) - 1)

?

> +static int hisi_lpc_acpi_xlat_io_res(struct acpi_device *adev,
> +				     struct acpi_device *host,
> +				     struct resource *res)
> +{
> +	unsigned long sys_port;

> +	resource_size_t len = res->end - res->start;

resource_size()

> +	return 0;
> +}


> +static int hisi_lpc_acpi_set_io_res(struct device *child,
> +				    struct device *hostdev,
> +				    const struct resource **res,
> +				    int *num_res)
> +{

> +	/*
> +	 * The following code segment to retrieve the resources is
> common to
> +	 * acpi_create_platform_device(), so consider a common helper
> function
> +	 * in future.
> +	 */
> +	count = acpi_dev_get_resources(adev, &resource_list, NULL,
> NULL);
> +	if (count <= 0) {
> +		dev_dbg(child, "failed to get resources\n");

> +		return count ? count : -EIO;

count == 0 --> return 0;

Is it by design? (I didn't check acpi_create_platform_device() though)

> +	}
> +
> +	resources = devm_kcalloc(hostdev, count, sizeof(*resources),
> +				 GFP_KERNEL);
> +	if (!resources) {
> +		dev_warn(hostdev, "could not allocate memory for %d
> resources\n",
> +			 count);
> +		acpi_dev_free_resource_list(&resource_list);
> +		return -ENOMEM;
> +	}
> +	count = 0;
> +	list_for_each_entry(rentry, &resource_list, node)
> +		resources[count++] = *rentry->res;
> +
> +	acpi_dev_free_resource_list(&resource_list);

> +
> +	return 0;
> +}

> +
> +/*
> + * hisi_lpc_acpi_probe - probe children for ACPI FW
> + * @hostdev: LPC host device pointer
> + *
> + * Returns 0 when successful, and a negative value for failure.
> + *
> + * Scan all child devices and create a per-device MFD with
> + * logical PIO translated IO resources.
> + */
> +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];

One line, please.

Just noticed that calloc() memory layout is not the same how you are
using it.

> +	/* 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));

No possibility of identical devices?

> +		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,

You mean it's not possible to have more than one identical device?

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


-- 
Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Intel Finland Oy