From 93e7a8f74cc2c9c7bc50b413654642a0347a55d2 Mon Sep 17 00:00:00 2001
From: Nick Brassel <nick@tzarc.org>
Date: Thu, 16 Jul 2020 16:58:14 +1000
Subject: Add dual-bank STM32 bootloader support, given GPIO toggle on BOOT0 to
 charge RC circuit. (#8778)

---
 tmk_core/common/chibios/bootloader.c | 84 +++++++++++++++++++++++++++++-------
 1 file changed, 69 insertions(+), 15 deletions(-)

(limited to 'tmk_core/common')

diff --git a/tmk_core/common/chibios/bootloader.c b/tmk_core/common/chibios/bootloader.c
index 4cf5dae7e6..dceeaa6b19 100644
--- a/tmk_core/common/chibios/bootloader.c
+++ b/tmk_core/common/chibios/bootloader.c
@@ -3,28 +3,82 @@
 #include "ch.h"
 #include "hal.h"
 
-#ifdef STM32_BOOTLOADER_ADDRESS
-/* STM32 */
-
 /* This code should be checked whether it runs correctly on platforms */
-#    define SYMVAL(sym) (uint32_t)(((uint8_t *)&(sym)) - ((uint8_t *)0))
+#define SYMVAL(sym) (uint32_t)(((uint8_t *)&(sym)) - ((uint8_t *)0))
+#define BOOTLOADER_MAGIC 0xDEADBEEF
+#define MAGIC_ADDR (unsigned long *)(SYMVAL(__ram0_end__) - 4)
+
+#ifndef STM32_BOOTLOADER_DUAL_BANK
+#    define STM32_BOOTLOADER_DUAL_BANK FALSE
+#endif
+
+#if STM32_BOOTLOADER_DUAL_BANK
+
+// Need pin definitions
+#    include "config_common.h"
+
+#    ifndef STM32_BOOTLOADER_DUAL_BANK_GPIO
+#        error "No STM32_BOOTLOADER_DUAL_BANK_GPIO defined, don't know which pin to toggle"
+#    endif
+
+#    ifndef STM32_BOOTLOADER_DUAL_BANK_POLARITY
+#        define STM32_BOOTLOADER_DUAL_BANK_POLARITY 0
+#    endif
+
+#    ifndef STM32_BOOTLOADER_DUAL_BANK_DELAY
+#        define STM32_BOOTLOADER_DUAL_BANK_DELAY 100000
+#    endif
+
+extern uint32_t __ram0_end__;
+
+#    define bootdelay(loopcount)                  \
+        do {                                      \
+            for (int i = 0; i < loopcount; ++i) { \
+                __asm__ volatile("nop\n\t"        \
+                                 "nop\n\t"        \
+                                 "nop\n\t");      \
+            }                                     \
+        } while (0)
+
+void bootloader_jump(void) {
+    *MAGIC_ADDR = BOOTLOADER_MAGIC;  // set magic flag => reset handler will jump into boot loader
+    NVIC_SystemReset();
+}
+
+void enter_bootloader_mode_if_requested(void) {
+    unsigned long *check = MAGIC_ADDR;
+    if (*check == BOOTLOADER_MAGIC) {
+        *check = 0;
+
+        // For STM32 MCUs with dual-bank flash, and we're incapable of jumping to the bootloader. The first valid flash
+        // bank is executed unconditionally after a reset, so it doesn't enter DFU unless BOOT0 is high. Instead, we do
+        // it with hardware...in this case, we pull a GPIO high/low depending on the configuration, connects 3.3V to
+        // BOOT0's RC charging circuit, lets it charge the capacitor, and issue a system reset. See the QMK discord
+        // #hardware channel pins for an example circuit.
+        palSetPadMode(PAL_PORT(STM32_BOOTLOADER_DUAL_BANK_GPIO), PAL_PAD(STM32_BOOTLOADER_DUAL_BANK_GPIO), PAL_MODE_OUTPUT_PUSHPULL);
+#    if STM32_BOOTLOADER_DUAL_BANK_POLARITY
+        palSetPad(PAL_PORT(STM32_BOOTLOADER_DUAL_BANK_GPIO), PAL_PAD(STM32_BOOTLOADER_DUAL_BANK_GPIO));
+#    else
+        palClearPad(PAL_PORT(STM32_BOOTLOADER_DUAL_BANK_GPIO), PAL_PAD(STM32_BOOTLOADER_DUAL_BANK_GPIO));
+#    endif
+
+        // Wait for a while for the capacitor to charge
+        bootdelay(STM32_BOOTLOADER_DUAL_BANK_DELAY);
+
+        // Issue a system reset to get the ROM bootloader to execute, with BOOT0 high
+        NVIC_SystemReset();
+    }
+}
+
+#elif defined(STM32_BOOTLOADER_ADDRESS)  // STM32_BOOTLOADER_DUAL_BANK
+
 extern uint32_t __ram0_end__;
-#    define BOOTLOADER_MAGIC 0xDEADBEEF
-#    define MAGIC_ADDR (unsigned long *)(SYMVAL(__ram0_end__) - 4)
 
-/** \brief Jump to the bootloader
- *
- * FIXME: needs doc
- */
 void bootloader_jump(void) {
     *MAGIC_ADDR = BOOTLOADER_MAGIC;  // set magic flag => reset handler will jump into boot loader
     NVIC_SystemReset();
 }
 
-/** \brief Enter bootloader mode if requested
- *
- * FIXME: needs doc
- */
 void enter_bootloader_mode_if_requested(void) {
     unsigned long *check = MAGIC_ADDR;
     if (*check == BOOTLOADER_MAGIC) {
@@ -41,7 +95,7 @@ void enter_bootloader_mode_if_requested(void) {
     }
 }
 
-#elif defined(KL2x) || defined(K20x) /* STM32_BOOTLOADER_ADDRESS */
+#elif defined(KL2x) || defined(K20x)  // STM32_BOOTLOADER_DUAL_BANK // STM32_BOOTLOADER_ADDRESS
 /* Kinetis */
 
 #    if defined(KIIBOHD_BOOTLOADER)
-- 
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