dm: core: Add a way of overriding the ACPI device path

Some devices such as GPIO need to override the normal path that would be
generated by driver model. Add a device-tree property for this.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Wolfgang Wallner <wolfgang.wallner@br-automation.com>

doc/device-tree-bindings/device.txt

@@ -17,6 +17,8 @@ the acpi,compatible property.
     System) Device Name)
  - acpi,hid : Contains the string to use as the HID (Hardware ID)
     identifier _HID
+ - acpi,path : Specifies the full ACPI path for a device. This overrides the
+    normal path built from the driver-model hierarchy
  - acpi,name : Provides the ACPI name for a device, which is a string consisting
    of four alphanumeric character (upper case)
  - acpi,uid : _UID value for device
@@ -47,3 +49,24 @@ pcie-a0@14,0 {
 		interrupts-extended = <&acpi_gpe 0x3c 0>;
 	};
 };
+
+p2sb: p2sb@d,0 {
+	u-boot,dm-pre-reloc;
+	reg = <0x02006810 0 0 0 0>;
+	compatible = "intel,apl-p2sb";
+	early-regs = <IOMAP_P2SB_BAR 0x100000>;
+	pci,no-autoconfig;
+
+	n {
+		compatible = "intel,apl-pinctrl";
+		u-boot,dm-pre-reloc;
+		intel,p2sb-port-id = <PID_GPIO_N>;
+		acpi,path = "\\_SB.GPO0";
+		gpio_n: gpio-n {
+			compatible = "intel,gpio";
+			u-boot,dm-pre-reloc;
+			gpio-controller;
+			#gpio-cells = <2>;
+			linux-name = "INT3452:00";
+		};
+	};

drivers/core/acpi.c

@@ -82,6 +82,25 @@ int acpi_get_name(const struct udevice *dev, char *out_name)
 	return 0;
 }
 
+int acpi_get_path(const struct udevice *dev, char *out_path, int maxlen)
+{
+	const char *path;
+	int ret;
+
+	path = dev_read_string(dev, "acpi,path");
+	if (path) {
+		if (strlen(path) >= maxlen)
+			return -E2BIG;
+		strcpy(out_path, path);
+		return 0;
+	}
+	ret = acpi_device_path(dev, out_path, maxlen);
+	if (ret)
+		return log_msg_ret("dev", ret);
+
+	return 0;
+}
+
 /**
  * acpi_add_item() - Add a new item to the list of data collected
  *

include/dm/acpi.h

@@ -187,6 +187,19 @@ int acpi_inject_dsdt(struct acpi_ctx *ctx);
  */
 void acpi_dump_items(enum acpi_dump_option option);
 
+/**
+ * acpi_get_path() - Get the full ACPI path for a device
+ *
+ * This checks for any override in the device tree and calls acpi_device_path()
+ * if not
+ *
+ * @dev: Device to check
+ * @out_path: Buffer to place the path in (should be ACPI_PATH_MAX long)
+ * @maxlen: Size of buffer (typically ACPI_PATH_MAX)
+ * @return 0 if OK, -ve on error
+ */
+int acpi_get_path(const struct udevice *dev, char *out_path, int maxlen);
+
 #endif /* __ACPI__ */
 
 #endif