Add filesystem code and storage syscalls

Adds syscalls:

- ALLOCATE_AREA
- DEALLOCATE_AREA
- WRITE_DATA
- READ_DATA

and code to access the filesystem and the flash over SPI.

Based on original work by Daniel Jobson <jobson@tillitis.see> for
these files:

- auth_app.[ch]
- flash.[ch]
- spi.[ch]
- partition_table.[ch]
- rng.[ch]
- storage.[ch]

which are used with small changes to integrate with the new syscall
method.

Co-authored-by: Daniel Jobson <jobson@tillitis.se>
Co-authored-by: Mikael Ågren <mikael@tillitis.se>

hw/application_fpga/fw/tk1/partition_table.c

@@ -0,0 +1,50 @@
+// Copyright (C) 2024 - Tillitis AB
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <stdint.h>
+#include <tkey/lib.h>
+
+#include "flash.h"
+#include "partition_table.h"
+#include "proto.h"
+
+int part_table_read(struct partition_table *part_table)
+{
+	// Read from flash, if it exists, otherwise create a new one.
+
+	flash_release_powerdown();
+	memset(part_table, 0x00, sizeof(*part_table));
+
+	flash_read_data(ADDR_PARTITION_TABLE, (uint8_t *)part_table,
+			sizeof(*part_table));
+
+	// TODO: Implement redundancy and consistency check
+
+	if (part_table->header.version != PART_TABLE_VERSION) {
+		// Partition table is not ours. Make a new one, and store it.
+		memset(part_table, 0x00, sizeof(*part_table));
+
+		part_table->header.version = PART_TABLE_VERSION;
+
+		for (int i = 0; i < 4; i++) {
+			part_table->app_storage[i].addr_start =
+			    (ADDR_STORAGE_AREA + i * SIZE_STORAGE_AREA);
+			part_table->app_storage[i].size = SIZE_STORAGE_AREA;
+		}
+
+		part_table_write(part_table);
+	}
+
+	// Now the partition table is synced between flash and RAM.
+
+	return 0;
+}
+
+int part_table_write(struct partition_table *part_table)
+{
+	flash_sector_erase(ADDR_PARTITION_TABLE);
+	flash_write_data(ADDR_PARTITION_TABLE, (uint8_t *)part_table,
+			 sizeof(*part_table));
+
+	return 0;
+}