echoplayer: allow enabling system debug in normal builds

Allow toggling the system debug state from the debug menu
in Rockbox, or by holding a button combo at boot, so that
an SWD/JTAG debugger can be attached to normal non-debug
builds without too much hassle.

Change-Id: Iee47ef916ade2e5ec1094a63c68e48f1b27b0bbb

bootloader/echoplayer.c

@@ -34,6 +34,7 @@
 #include "rbversion.h"
 #include "system-echoplayer.h"
 #include "gpio-stm32h7.h"
+#include "regs/cortex-m/cm_debug.h"
 
 #define SDRAM_SIZE          (MEMORYSIZE * 1024 * 1024)
 
@@ -136,6 +137,14 @@ static bool is_usbmode_button_pressed(void)
     return button_status() & BUTTON_DOWN;
 }
 
+static bool is_sysdebug_button_pressed(void)
+{
+    const int mask = BUTTON_A | BUTTON_B;
+
+    /* Both buttons must be held */
+    return (button_status() & mask) == mask;
+}
+
 static int send_event_on_tmo(struct timeout *tmo)
 {
     button_queue_post(tmo->data, 0);
@@ -370,6 +379,13 @@ void main(void)
     power_init();
     button_init();
 
+    /* Enable system debugging if button combo held or debugger attached */
+    if (reg_readf(CM_DEBUG_DHCSR, C_DEBUGEN) ||
+        is_sysdebug_button_pressed())
+    {
+        system_debug_enable(true);
+    }
+
     /* Start monitoring power button / usb state */
     monitor_init();
 

firmware/SOURCES

@@ -1943,7 +1943,9 @@ target/arm/rk27xx/ihifi2/audio-ihifi800.c
 target/arm/stm32/crt0-stm32h7.S
 target/arm/stm32/vectors-stm32h7.S
 target/arm/stm32/adc-stm32h7.c
+#ifndef BOOTLOADER
 target/arm/stm32/debug-stm32h7.c
+#endif
 target/arm/stm32/gpio-stm32h7.c
 target/arm/stm32/i2c-stm32h7.c
 target/arm/stm32/pcm-stm32h7.c

firmware/reggen/cortex-m.regs

@@ -168,3 +168,10 @@ CM_SYSTICK @ 0xe000e000 : block {
         23 00 TENMS
     }
 }
+
+// Debug
+CM_DEBUG @ 0xe000edf0 : block {
+    DHCSR @ 0x00 : reg {
+        0 C_DEBUGEN
+    }
+}

firmware/target/arm/stm32/debug-stm32h7.c

@@ -19,10 +19,115 @@
  *
  ****************************************************************************/
 #include "system.h"
+#include "kernel.h"
+#include "button.h"
+#include "lcd.h"
+#include "font.h"
+#include "action.h"
+#include "list.h"
+#include "regs/stm32h743/dbgmcu.h"
+#include "regs/cortex-m/cm_debug.h"
+#include <stdio.h>
+
+enum
+{
+    SWD_MENU_IS_ENABLED,
+    SWD_MENU_IS_ATTACHED,
+    SWD_MENU_NUM_ENTRIES
+};
+
+static int swd_menu_action_cb(int action, struct gui_synclist *lists)
+{
+    int sel = gui_synclist_get_sel_pos(lists);
+
+    if (sel == SWD_MENU_IS_ENABLED && action == ACTION_STD_OK)
+    {
+        if (reg_readf(DBGMCU_CR, DBGSLEEP_D1))
+            system_debug_enable(false);
+        else
+            system_debug_enable(true);
+
+        action = ACTION_REDRAW;
+    }
+
+    if (action == ACTION_NONE)
+        action = ACTION_REDRAW;
+
+    return action;
+}
+
+static const char *swd_menu_get_name(int item, void *data, char *buf, size_t bufsz)
+{
+    (void)data;
+
+    switch (item)
+    {
+    case SWD_MENU_IS_ENABLED:
+        snprintf(buf, bufsz, "System debug enabled: %d",
+                 (int)!!reg_readf(DBGMCU_CR, DBGSLEEP_D1));
+        return buf;
+
+    case SWD_MENU_IS_ATTACHED:
+        snprintf(buf, bufsz, "DHCSR.C_DEBUGEN bit: %d",
+                 (int)!!reg_readf(CM_DEBUG_DHCSR, C_DEBUGEN));
+        return buf;
+
+    default:
+        return "";
+    }
+}
+
+static bool swd_menu(void)
+{
+    struct simplelist_info info;
+    simplelist_info_init(&info, "SWD/JTAG", SWD_MENU_NUM_ENTRIES, NULL);
+    info.action_callback = swd_menu_action_cb;
+    info.get_name = swd_menu_get_name;
+    return simplelist_show_list(&info);
+}
+
+/* Menu definition */
+static const struct {
+    const char *name;
+    bool (*function) (void);
+} menuitems[] = {
+    {"SWD/JTAG", swd_menu},
+};
+
+static int hw_info_menu_action_cb(int btn, struct gui_synclist *lists)
+{
+    if (btn == ACTION_STD_OK)
+    {
+        int sel = gui_synclist_get_sel_pos(lists);
+        FOR_NB_SCREENS(i)
+            viewportmanager_theme_enable(i, false, NULL);
+
+        menuitems[sel].function();
+        btn = ACTION_REDRAW;
+
+        FOR_NB_SCREENS(i)
+            viewportmanager_theme_undo(i, false);
+    }
+
+    return btn;
+}
+
+static const char* hw_info_menu_get_name(int item, void *data, char *buf, size_t bufsz)
+{
+    (void)buf;
+    (void)bufsz;
+    (void)data;
+    return menuitems[item].name;
+}
 
 bool dbg_hw_info(void)
 {
-    return false;
+    struct simplelist_info info;
+    simplelist_info_init(&info, MODEL_NAME " debug menu",
+                         ARRAYLEN(menuitems), NULL);
+    info.action_callback = hw_info_menu_action_cb;
+    info.get_name = hw_info_menu_get_name;
+    return simplelist_show_list(&info);
 }
 
 bool dbg_ports(void)