Initial firmware commit.

firmware/application/m4_startup.cpp

@@ -0,0 +1,53 @@
+/*
+ * Copyright (C) 2015 Jared Boone, ShareBrained Technology, Inc.
+ *
+ * This file is part of PortaPack.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; see the file COPYING.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#include "m4_startup.hpp"
+
+#include "hal.h"
+
+#include <cstdint>
+#include <cstddef>
+#include <cstring>
+
+static constexpr uint32_t m4_text_flash_image_offset = 0x10000;
+static constexpr size_t m4_text_size = 0x8000;
+static constexpr uint32_t m4_text_flash_base = LPC_SPIFI_DATA_CACHED_BASE + m4_text_flash_image_offset;
+static constexpr uint32_t m4_text_ram_base = 0x10080000;
+
+/* TODO: OK, this is cool, but how do I put the M4 to sleep so I can switch to
+ * a different image? Other than asking the old image to sleep while the M0
+ * makes changes?
+ *
+ * I suppose I could force M4MEMMAP to an invalid memory reason which would
+ * cause an exception and effectively halt the M4. But that feels gross.
+ */
+void m4_init() {
+	/* Initialize M4 code RAM */
+	std::memcpy((void*)m4_text_ram_base, (void*)m4_text_flash_base, m4_text_size);
+
+	/* M4 core is assumed to be sleeping with interrupts off, so we can mess
+	 * with its address space and RAM without concern.
+	 */
+	LPC_CREG->M4MEMMAP = m4_text_ram_base;
+
+	/* Reset M4 core */
+	LPC_RGU->RESET_CTRL[0] = (1 << 13);
+}