altos: Enable STM SYSCFG when routing EXTI

The EXTI routing information is in the syscfg unit, so that needs to
be powered up or writes to its registers will be lost.

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

diff --git a/src/stm/stm32l.h b/src/stm/stm32l.h
index 3a498a0a06043febab4b3bca22e38e5dc041e019..25f5af073d76659b3ec7cba65252d6f19b8161fc 100644 (file)
--- a/src/stm/stm32l.h
+++ b/src/stm/stm32l.h
@@ -905,6 +905,9 @@ stm_exticr_set(struct stm_gpio *gpio, int pin) {
        uint8_t shift = (pin & 3) << 2;
        uint8_t val = 0;
 
+       /* Enable SYSCFG */
+       stm_rcc.apb2enr |= (1 << STM_RCC_APB2ENR_SYSCFGEN);
+
        if (gpio == &stm_gpioa)
                val = STM_SYSCFG_EXTICR_PA;
        else if (gpio == &stm_gpiob)