sram2 standby working

semestralka_2/src/sleep/standby.rs

@@ -11,3 +11,32 @@ pub fn enter_standby() -> ! {
     
     cortex_m::asm::udf(); // never happen marker
 }
+
+pub fn enter_standby_with_sram2_retention() -> ! {
+    sram2_retention();
+    enter_standby();
+}
+
+pub fn sram2_retention() {
+    unsafe extern "C" {
+        fn HAL_PWREx_EnableSRAM2ContentStandbyRetention(sram2_pages: u32);
+    }
+
+    unsafe {
+        // 0x60 = PWR_SRAM2_FULL_STANDBY = PWR_CR1_RRSB1 | PWR_CR1_RRSB2
+        // See: STM32U5xx HAL: stm32u5xx_hal_pwr_ex.h line 227
+        //      CMSIS: PWR_CR1_RRSB1=0x20, PWR_CR1_RRSB2=0x40
+        HAL_PWREx_EnableSRAM2ContentStandbyRetention(0x60);
+    }
+}
+
+pub fn disable_sram2_retention() {
+    unsafe extern "C" {
+        fn HAL_PWREx_DisableSRAM2ContentStandbyRetention(sram2_pages: u32);
+    }
+
+    unsafe {
+        // Disable full SRAM2 retention
+        HAL_PWREx_DisableSRAM2ContentStandbyRetention(0x60);
+    }
+}