cpu/stm32_common: minimize consumption on STM32L1

cpu/stm32_common/cpu_init.c

@@ -26,6 +26,7 @@
  * @author      Víctor Ariño <victor.arino@zii.aero>
  * @author      Kaspar Schleiser <kaspar@schleiser.de>
  * @author      Vincent Dupont <vincent@otakeys.com>
+ * @author      Oleg Artamonov <oleg@unwds.com>
  *
  * @}
  */
@@ -49,6 +50,28 @@ void cpu_init(void)
     periph_clk_en(APB1, BIT_APB_PWREN);
     /* initialize the system clock as configured in the periph_conf.h */
     stmclk_init_sysclk();
+
+#if defined(CPU_FAM_STM32L1)
+    uint32_t ahb_gpio_clocks;
+    GPIO_TypeDef *port;
+
+    /* enable GPIO clock and save GPIO clock configuration */
+    ahb_gpio_clocks = RCC->AHBENR & 0xFF;
+    periph_clk_en(AHB, 0xFF);
+
+    /* switch all GPIOs to AIN mode to minimize power consumption */
+    /* can't be more than 12 ports on STM32L1 */
+    for (int i = 0; i < 12; i++) {
+        port = (GPIO_TypeDef *)(GPIOA_BASE + i*(GPIOB_BASE - GPIOA_BASE));
+        if (IS_GPIO_ALL_INSTANCE(port))
+            port->MODER = 0xffffffff;
+        else
+            break;
+        }
+    /* restore GPIO clock */
+    periph_clk_en(AHB, ((RCC->AHBENR & ~((uint32_t)0xFF)) | ahb_gpio_clocks));
+    }
+#endif
 #ifdef MODULE_PERIPH_DMA
     /*  initialize DMA streams */
     dma_init();