refactor(rpi): move more platform-specific code into common

In preparation for RPi 5 support, which will reuse most of the RPi 4
logic except for DTB patching.

Change-Id: I6f6ef96933711a1798757a3389adae1b8ee3de6c
Signed-off-by: Mario Bălănică <mariobalanica02@gmail.com>
diff --git a/plat/rpi/rpi4/rpi4_setup.c b/plat/rpi/rpi4/rpi4_setup.c
new file mode 100644
index 0000000..82200b9
--- /dev/null
+++ b/plat/rpi/rpi4/rpi4_setup.c
@@ -0,0 +1,109 @@
+/*
+ * Copyright (c) 2016-2024, Arm Limited and Contributors. All rights reserved.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <assert.h>
+#include <inttypes.h>
+#include <stdint.h>
+
+#include <arch_helpers.h>
+#include <common/fdt_fixup.h>
+#include <common/fdt_wrappers.h>
+
+#include <rpi_shared.h>
+
+/*
+ * Remove the FDT /memreserve/ entry that covers the region at the very
+ * beginning of memory (if that exists). This is where the secondaries
+ * originally spin, but we pull them out there.
+ * Having overlapping /reserved-memory and /memreserve/ regions confuses
+ * the Linux kernel, so we need to get rid of this one.
+ */
+static void remove_spintable_memreserve(void *dtb)
+{
+	uint64_t addr, size;
+	int regions = fdt_num_mem_rsv(dtb);
+	int i;
+
+	for (i = 0; i < regions; i++) {
+		if (fdt_get_mem_rsv(dtb, i, &addr, &size) != 0) {
+			return;
+		}
+		if (size == 0U) {
+			return;
+		}
+		/* We only look for the region at the beginning of DRAM. */
+		if (addr != 0U) {
+			continue;
+		}
+		/*
+		 * Currently the region in the existing DTs is exactly 4K
+		 * in size. Should this value ever change, there is probably
+		 * a reason for that, so inform the user about this.
+		 */
+		if (size == 4096U) {
+			fdt_del_mem_rsv(dtb, i);
+			return;
+		}
+		WARN("Keeping unknown /memreserve/ region at 0, size: %" PRId64 "\n",
+		     size);
+	}
+}
+
+static void rpi4_prepare_dtb(void)
+{
+	void *dtb = (void *)rpi4_get_dtb_address();
+	uint32_t gic_int_prop[3];
+	int ret, offs;
+
+	/* Return if no device tree is detected */
+	if (fdt_check_header(dtb) != 0)
+		return;
+
+	ret = fdt_open_into(dtb, dtb, 0x100000);
+	if (ret < 0) {
+		ERROR("Invalid Device Tree at %p: error %d\n", dtb, ret);
+		return;
+	}
+
+	if (dt_add_psci_node(dtb)) {
+		ERROR("Failed to add PSCI Device Tree node\n");
+		return;
+	}
+
+	if (dt_add_psci_cpu_enable_methods(dtb)) {
+		ERROR("Failed to add PSCI cpu enable methods in Device Tree\n");
+		return;
+	}
+
+	/*
+	 * Remove the original reserved region (used for the spintable), and
+	 * replace it with a region describing the whole of Trusted Firmware.
+	 */
+	remove_spintable_memreserve(dtb);
+	if (fdt_add_reserved_memory(dtb, "atf@0", 0, 0x80000))
+		WARN("Failed to add reserved memory nodes to DT.\n");
+
+	offs = fdt_node_offset_by_compatible(dtb, 0, "arm,gic-400");
+	gic_int_prop[0] = cpu_to_fdt32(1);		// PPI
+	gic_int_prop[1] = cpu_to_fdt32(9);		// PPI #9
+	gic_int_prop[2] = cpu_to_fdt32(0x0f04);		// all cores, level high
+	fdt_setprop(dtb, offs, "interrupts", gic_int_prop, 12);
+
+	offs = fdt_path_offset(dtb, "/chosen");
+	fdt_setprop_string(dtb, offs, "stdout-path", "serial0");
+
+	ret = fdt_pack(dtb);
+	if (ret < 0)
+		ERROR("Failed to pack Device Tree at %p: error %d\n", dtb, ret);
+
+	clean_dcache_range((uintptr_t)dtb, fdt_blob_size(dtb));
+	INFO("Changed device tree to advertise PSCI.\n");
+}
+
+void plat_rpi_bl31_custom_setup(void)
+{
+	rpi4_prepare_dtb();
+}