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/spi.c

@@ -0,0 +1,90 @@
+// Copyright (C) 2024 - Tillitis AB
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include "spi.h"
+#include <tkey/tk1_mem.h>
+
+#include <stddef.h>
+#include <stdint.h>
+
+// clang-format off
+static volatile uint32_t *spi_en =         (volatile uint32_t *)(TK1_MMIO_TK1_BASE | 0x200);
+static volatile uint32_t *spi_xfer =       (volatile uint32_t *)(TK1_MMIO_TK1_BASE | 0x204);
+static volatile uint32_t *spi_data =       (volatile uint32_t *)(TK1_MMIO_TK1_BASE | 0x208);
+// clang-format on
+
+// returns non-zero when the SPI-master is ready, and zero if not
+// ready. This can be used to check if the SPI-master is available
+// in the hardware.
+int spi_ready(void)
+{
+	return *spi_xfer;
+}
+
+static void spi_enable(void)
+{
+	*spi_en = 1;
+}
+
+static void spi_disable(void)
+{
+	*spi_en = 0;
+}
+
+static void _spi_write(uint8_t *cmd, size_t size)
+{
+	for (size_t i = 0; i < size; i++) {
+		while (!spi_ready()) {
+		}
+
+		*spi_data = cmd[i];
+		*spi_xfer = 1;
+	}
+
+	while (!spi_ready()) {
+	}
+}
+
+static void _spi_read(uint8_t *buf, size_t size)
+{
+
+	while (!spi_ready()) {
+	}
+
+	for (size_t i = 0; i < size; i++) {
+
+		*spi_data = 0x00;
+		*spi_xfer = 1;
+
+		// wait until spi master is done
+		while (!spi_ready()) {
+		}
+
+		buf[i] = (*spi_data & 0xff);
+	}
+}
+
+// Function to both read and write data to the connected SPI flash.
+int spi_transfer(uint8_t *cmd, size_t cmd_size, uint8_t *tx_buf, size_t tx_size,
+		 uint8_t *rx_buf, size_t rx_size)
+{
+	if (cmd == NULL || cmd_size == 0) {
+		return -1;
+	}
+
+	spi_enable();
+
+	_spi_write(cmd, cmd_size);
+
+	if (tx_buf != NULL || tx_size != 0) {
+		_spi_write(tx_buf, tx_size);
+	}
+
+	if (rx_buf != NULL && rx_size != 0) {
+		_spi_read(rx_buf, rx_size);
+	}
+
+	spi_disable();
+
+	return 0;
+}