Add STM self-flashing loader

This allows the real application to get loaded at 0x2000 and jumps to
that at startup time if the boot pin is set appropriately

Signed-off-by: Keith Packard <keithp@keithp.com>

2 files changed, 60 insertions, 3 deletions

diff --git a/src/stm/ao_arch_funcs.h b/src/stm/ao_arch_funcs.h
index f3d68202..2c0f173c 100644
--- a/src/stm/ao_arch_funcs.h
+++ b/src/stm/ao_arch_funcs.h
@@ -113,6 +113,19 @@ ao_spi_init(void);
 			stm_rcc.ahbenr |= (1 << STM_RCC_AHBENR_GPIOEEN); \
 	} while (0)
 
+#define ao_disable_port(port) do {					\
+		if ((port) == &stm_gpioa)				\
+			stm_rcc.ahbenr &= ~(1 << STM_RCC_AHBENR_GPIOAEN); \
+		else if ((port) == &stm_gpiob)				\
+			stm_rcc.ahbenr &= ~(1 << STM_RCC_AHBENR_GPIOBEN); \
+		else if ((port) == &stm_gpioc)				\
+			stm_rcc.ahbenr &= ~(1 << STM_RCC_AHBENR_GPIOCEN); \
+		else if ((port) == &stm_gpiod)				\
+			stm_rcc.ahbenr &= ~(1 << STM_RCC_AHBENR_GPIODEN); \
+		else if ((port) == &stm_gpioe)				\
+			stm_rcc.ahbenr &= ~(1 << STM_RCC_AHBENR_GPIOEEN); \
+	} while (0)
+
 
 #define ao_gpio_set(port, bit, pin, v) stm_gpio_set(port, bit, v)
 
@@ -124,9 +137,7 @@ ao_spi_init(void);
 		stm_moder_set(port, bit, STM_MODER_OUTPUT);\
 	} while (0)
 
-#define ao_enable_input(port,bit,mode) do {				\
-		ao_enable_port(port);					\
-		stm_moder_set(port, bit, STM_MODER_INPUT);		\
+#define ao_gpio_set_mode(port,bit,mode) do {				\
 		if (mode == AO_EXTI_MODE_PULL_UP)			\
 			stm_pupdr_set(port, bit, STM_PUPDR_PULL_UP);	\
 		else if (mode == AO_EXTI_MODE_PULL_DOWN)		\
@@ -134,6 +145,12 @@ ao_spi_init(void);
 		else							\
 			stm_pupdr_set(port, bit, STM_PUPDR_NONE);	\
 	} while (0)
+	
+#define ao_enable_input(port,bit,mode) do {				\
+		ao_enable_port(port);					\
+		stm_moder_set(port, bit, STM_MODER_INPUT);		\
+		ao_gpio_set_mode(port, bit, mode);			\
+	} while (0)
 
 #define ao_enable_cs(port,bit) do {				\
 		stm_gpio_set((port), bit, 1);			\
diff --git a/src/stm/ao_interrupt.c b/src/stm/ao_interrupt.c
index a423d8b1..12763a30 100644
--- a/src/stm/ao_interrupt.c
+++ b/src/stm/ao_interrupt.c
@@ -36,7 +36,47 @@ void stm_ignore_isr(void)
 {
 }
 
+const void *stm_interrupt_vector[];
+
+#define BOOT_FETCH(o)	(*((uint32_t *) (AO_BOOT_APPLICATION_BASE + (o))))
+
+#ifdef AO_BOOT_APPLICATION_PIN
+#include <ao_exti.h>
+#endif
+
 void start(void) {
+#ifdef AO_BOOT_APPLICATION_PIN
+	uint16_t v;
+
+	/* Enable power interface clock */
+	stm_rcc.apb1enr |= (1 << STM_RCC_APB1ENR_PWREN);
+	
+	/* Enable the input pin */
+	ao_enable_input(&AO_BOOT_APPLICATION_GPIO, AO_BOOT_APPLICATION_PIN,
+			AO_BOOT_APPLICATION_MODE);
+
+	/* Read the value */
+	v = stm_gpio_get(&AO_BOOT_APPLICATION_GPIO, AO_BOOT_APPLICATION_PIN);
+
+	/* Reset the chip to turn off the port and the power interface clock */
+	ao_gpio_set_mode(&AO_BOOT_APPLICATION_GPIO, AO_BOOT_APPLICATION_PIN, 0);
+	ao_disable_port(&AO_BOOT_APPLICATION_GPIO);
+	stm_rcc.apb1enr &= ~(1 << STM_RCC_APB1ENR_PWREN);
+	if (v == AO_BOOT_APPLICATION_VALUE)
+	{
+		uint32_t	sp;
+		uint32_t	pc;
+
+		sp = BOOT_FETCH(0);
+		pc = BOOT_FETCH(4);
+		asm ("mov sp, %0" : : "r" (sp));
+		asm ("mov lr, %0" : : "r" (pc));
+		asm ("bx lr");
+	}
+#endif
+
+	/* Set interrupt vector table offset */
+	stm_nvic.vto = (uint32_t) &stm_interrupt_vector;
 	memcpy(&__data_start__, &__text_end__, &__data_end__ - &__data_start__);
 	memset(&__bss_start__, '\0', &__bss_end__ - &__bss_start__);
 	main();