New WIP port: Echo R1

The Echo R1 is a new open-hardware music player design, based
on the STM32H743 microcontroller. Schematics and hardware
documentation for it can be found here:

- https://github.com/amachronic/echoplayer

This is an incomplete port. The bootloader can be loaded using
OpenOCD and it can draw to the LCD using SPI. SDRAM is working
but hasn't been extensively tested.

Change-Id: Ifd2bee15c49868fbc989683d3ca14dce48bf3e18

apps/SOURCES

@@ -299,4 +299,6 @@ keymaps/keymap-fiiom3k.c
 keymaps/keymap-erosq.c
 #elif CONFIG_KEYPAD == SHANLING_Q1_PAD
 keymaps/keymap-shanlingq1.c
+#elif CONFIG_KEYPAD == ECHO_R1_PAD
+keymaps/keymap-echor1.c
 #endif

apps/keymaps/keymap-echor1.c

@@ -0,0 +1,42 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * Copyright (C) 2025 Aidan MacDonald
+ *
+ * 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
+ * of the License, or (at your option) any later version.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+
+/* Button Code Definitions for Echo R1 */
+
+#include "config.h"
+#include "action.h"
+#include "button.h"
+#include "settings.h"
+
+/* {Action Code,    Button code,    Prereq button code } */
+
+static const struct button_mapping button_context_standard[] = {
+    LAST_ITEM_IN_LIST
+}; /* button_context_standard */
+
+const struct button_mapping* get_context_mapping(int context)
+{
+    switch (context)
+    {
+    default:
+        return button_context_standard;
+    }
+}

apps/settings.h

@@ -238,6 +238,9 @@ enum {  ALARM_START_WPS = 0,
 #elif CONFIG_CPU == S3C2440 || defined(CPU_PP) || CONFIG_CPU==IMX31L
 /* up to 64MB of DRAM at 0x0 */
 #define VIRT_PTR ((unsigned char*)0x4000000)
+#elif CONFIG_CPU == STM32H743
+/* 64k ITCM at 0x0 */
+#define VIRT_PTR ((unsigned char*)0x10000)
 #else
 /* offset from 0x0 slightly */
 #define VIRT_PTR ((unsigned char*)sizeof(char*))