HISI LPC: Re-Add ACPI child enumeration support

Since we no longer use the MFD APIs to enumerate the
child devices on the bus, use the platform driver APIs
directly.

In this patch we iterate of the children devices for the
host, and create a platform device directly per child.

For the iterating, we match the child ACPI HID against a
known list of supported child devices and their respective
ACPIs HID, to find the device name and any other
supplementary data.

Signed-off-by: John Garry <john.garry@huawei.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Wei Xu <xuwei5@hisilicon.com>

drivers/bus/hisi_lpc.c

@@ -442,12 +442,28 @@ static int hisi_lpc_acpi_set_io_res(struct device *child,
 	return 0;
 }
 
+static int hisi_lpc_acpi_remove_subdev(struct device *dev, void *unused)
+{
+	platform_device_unregister(to_platform_device(dev));
+	return 0;
+}
+
+struct hisi_lpc_acpi_cell {
+	const char *hid;
+	const char *name;
+	void *pdata;
+	size_t pdata_size;
+};
+
 /*
  * hisi_lpc_acpi_probe - probe children for ACPI FW
  * @hostdev: LPC host device pointer
  *
  * Returns 0 when successful, and a negative value for failure.
  *
+ * Create a platform device per child, fixing up the resources
+ * from bus addresses to Logical PIO addresses.
+ *
  */
 static int hisi_lpc_acpi_probe(struct device *hostdev)
 {
@@ -457,17 +473,75 @@ static int hisi_lpc_acpi_probe(struct device *hostdev)
 
 	/* Only consider the children of the host */
 	list_for_each_entry(child, &adev->children, node) {
+		const char *hid = acpi_device_hid(child);
+		const struct hisi_lpc_acpi_cell *cell;
+		struct platform_device *pdev;
 		const struct resource *res;
+		bool found = false;
 		int num_res;
 
 		ret = hisi_lpc_acpi_set_io_res(&child->dev, &adev->dev, &res,
 					       &num_res);
 		if (ret) {
 			dev_warn(hostdev, "set resource fail (%d)\n", ret);
+			goto fail;
+		}
+
+		cell = (struct hisi_lpc_acpi_cell []){
+			/* ipmi */
+			{
+				.hid = "IPI0001",
+				.name = "hisi-lpc-ipmi",
+			},
+			{}
+		};
+
+		for (; cell && cell->name; cell++) {
+			if (!strcmp(cell->hid, hid)) {
+				found = true;
+				break;
+			}
 		}
+
+		if (!found) {
+			dev_warn(hostdev,
+				 "could not find cell for child device (%s)\n",
+				 hid);
+			ret = -ENODEV;
+			goto fail;
+		}
+
+		pdev = platform_device_alloc(cell->name, PLATFORM_DEVID_AUTO);
+		if (!pdev) {
+			ret = -ENOMEM;
+			goto fail;
+		}
+
+		pdev->dev.parent = hostdev;
+		ACPI_COMPANION_SET(&pdev->dev, child);
+
+		ret = platform_device_add_resources(pdev, res, num_res);
+		if (ret)
+			goto fail;
+
+		ret = platform_device_add_data(pdev, cell->pdata,
+					       cell->pdata_size);
+		if (ret)
+			goto fail;
+
+		ret = platform_device_add(pdev);
+		if (ret)
+			goto fail;
+
+		acpi_device_set_enumerated(child);
 	}
 
 	return 0;
+
+fail:
+	device_for_each_child(hostdev, NULL,
+			      hisi_lpc_acpi_remove_subdev);
+	return ret;
 }
 
 static const struct acpi_device_id hisi_lpc_acpi_match[] = {