stm32: Reorganize stm32h7.c into major code blocks

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

src/stm32/stm32h7.c

@@ -4,15 +4,17 @@
 //
 // This file may be distributed under the terms of the GNU GPLv3 license.
 
-
-// I2C is not supported
-
 #include "autoconf.h" // CONFIG_CLOCK_REF_FREQ
 #include "board/armcm_boot.h" // VectorTable
 #include "command.h" // DECL_CONSTANT_STR
 #include "internal.h" // enable_pclock
 #include "sched.h" // sched_main
 
+
+/****************************************************************
+ * Clock setup
+ ****************************************************************/
+
 #define FREQ_PERIPH (CONFIG_CLOCK_FREQ / 4)
 
 // Enable a peripheral clock
@@ -101,12 +103,6 @@ gpio_clock_enable(GPIO_TypeDef *regs)
     enable_pclock((uint32_t)regs);
 }
 
-// Handle USB reboot requests
-void
-usb_request_bootloader(void)
-{
-}
-
 #if !CONFIG_STM32_CLOCK_REF_INTERNAL
 DECL_CONSTANT_STR("RESERVE_PINS_crystal", "PH0,PH1");
 #endif
@@ -224,13 +220,28 @@ clock_setup(void)
     }
 }
 
+
+/****************************************************************
+ * USB bootloader
+ ****************************************************************/
+
+// Handle USB reboot requests
+void
+usb_request_bootloader(void)
+{
+}
+
+
+/****************************************************************
+ * Startup
+ ****************************************************************/
+
 // Main entry point - called from armcm_boot.c:ResetHandler()
 void
 armcm_main(void)
 {
     // Run SystemInit() and then restore VTOR
     SystemInit();
-
     SCB->VTOR = (uint32_t)VectorTable;
 
     clock_setup();