From 8b1e3c3fb25e3d3fbec49158ba9dba9b07c9be00 Mon Sep 17 00:00:00 2001
From: Eric Callahan <arksine.code@gmail.com>
Date: Tue, 31 May 2022 06:51:25 -0400
Subject: [PATCH] armcm_reset: support canboot detection

When CanBoot is detected set its bypass signature when a
reset is requested.

Add a "try_request_canboot()" method that may be called
from from USB and Canbus bootloader requests.

Signed-off-by:  Eric Callahan <arksine.code@gmail.com>
---
 src/generic/armcm_reset.c | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/src/generic/armcm_reset.c b/src/generic/armcm_reset.c
index 19c2096d..b7aea955 100644
--- a/src/generic/armcm_reset.c
+++ b/src/generic/armcm_reset.c
@@ -6,10 +6,42 @@
 
 #include "board/internal.h" // NVIC_SystemReset
 #include "command.h" // DECL_COMMAND_FLAGS
+#include "autoconf.h"  // CONFIG_FLASH_START
+#include "irq.h"     // irq_disable
+
+#define CANBOOT_SIGNATURE 0x21746f6f426e6143
+#define CANBOOT_REQUEST   0x5984E3FA6CA1589B
+#define CANBOOT_BYPASS    0x7b06ec45a9a8243d
+
+static void
+canboot_reset(uint64_t req_signature)
+{
+    if (!(CONFIG_FLASH_START & 0x00FFFFFF))
+        // No bootloader
+        return;
+    uint32_t *bl_vectors = (uint32_t *)(CONFIG_FLASH_START & 0xFF000000);
+    uint64_t *boot_sig = (uint64_t *)(bl_vectors[1] - 9);
+    uint64_t *req_sig = (uint64_t *)bl_vectors[0];
+    if (boot_sig == (void *)ALIGN((size_t)boot_sig, 8) &&
+        *boot_sig == CANBOOT_SIGNATURE &&
+        req_sig == (void *)ALIGN((size_t)req_sig, 8))
+    {
+        irq_disable();
+        *req_sig = req_signature;
+        NVIC_SystemReset();
+    }
+}
+
+void
+try_request_canboot(void)
+{
+    canboot_reset(CANBOOT_REQUEST);
+}
 
 void
 command_reset(uint32_t *args)
 {
+    canboot_reset(CANBOOT_BYPASS);
     NVIC_SystemReset();
 }
 DECL_COMMAND_FLAGS(command_reset, HF_IN_SHUTDOWN, "reset");