acpi: Move PCI functions to separate file

Signed-off-by: Tim Wawrzynczak <twawrzynczak@chromium.org>
Change-Id: Idc96b99da9f9037267c0bec2c839014b13ceb8cc
Reviewed-on: https://review.coreboot.org/c/coreboot/+/51106
Reviewed-by: Furquan Shaikh <furquan@google.com>
Reviewed-by: Lance Zhao
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/acpi/acpigen_pci.c

@@ -0,0 +1,26 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <acpi/acpigen.h>
+#include <acpi/acpigen_pci.h>
+#include <assert.h>
+#include <device/device.h>
+#include <device/pci_def.h>
+#include <device/pci_type.h>
+#include <types.h>
+
+void acpigen_write_ADR_pci_devfn(pci_devfn_t devfn)
+{
+	/*
+	 * _ADR for PCI Bus is encoded as follows:
+	 * [63:32] - unused
+	 * [31:16] - device #
+	 * [15:0]  - function #
+	 */
+	acpigen_write_ADR(PCI_SLOT(devfn) << 16 | PCI_FUNC(devfn));
+}
+
+void acpigen_write_ADR_pci_device(const struct device *dev)
+{
+	assert(dev->path.type == DEVICE_PATH_PCI);
+	acpigen_write_ADR_pci_devfn(dev->path.pci.devfn);
+}