stm32mp1: add watchdog support

Introduce driver for STM32 IWDG peripheral (Independent Watchdog).
It is configured according to device tree content and should be enabled
from there.
The watchdog is not started by default. It can be started after an HW
reset if the dedicated OTP is fused.

The watchdog also needs to be frozen if a debugger is attached.
This is done by configuring the correct bits in DBGMCU.
This configuration is allowed by checking BSEC properties.

An increase of BL2 size is also required when adding this new code.

Change-Id: Ide7535d717885ce2f9c387cf17afd8b5607f3e7f
Signed-off-by: Yann Gautier <yann.gautier@st.com>
Signed-off-by: Lionel Debieve <lionel.debieve@st.com>
Signed-off-by: Nicolas Le Bayon <nicolas.le.bayon@st.com>
diff --git a/plat/st/common/include/stm32mp_common.h b/plat/st/common/include/stm32mp_common.h
index 4bbc4db..f8b5e7b 100644
--- a/plat/st/common/include/stm32mp_common.h
+++ b/plat/st/common/include/stm32mp_common.h
@@ -28,6 +28,17 @@
 /* Return the base address of the RCC peripheral */
 uintptr_t stm32mp_rcc_base(void);
 
+/* Get IWDG platform instance ID from peripheral IO memory base address */
+uint32_t stm32_iwdg_get_instance(uintptr_t base);
+
+/* Return bitflag mask for expected IWDG configuration from OTP content */
+uint32_t stm32_iwdg_get_otp_config(uint32_t iwdg_inst);
+
+#if defined(IMAGE_BL2)
+/* Update OTP shadow registers with IWDG configuration from device tree */
+uint32_t stm32_iwdg_shadow_update(uint32_t iwdg_inst, uint32_t flags);
+#endif
+
 /*
  * Platform util functions for the GPIO driver
  * @bank: Target GPIO bank ID as per DT bindings