MCU specific sleep feature is now defined in MCU specific file.

mcu/chx-stm32f103.c

@@ -0,0 +1,60 @@
+#include <stdint.h>
+#include <mcu/stm32f103.h>
+
+extern int chx_allow_sleep;
+
+static void
+configure_clock (uint32_t cfg_sw)
+{
+  RCC->CFGR = (RCC->CFGR & ~RCC_CFGR_SW_MASK) | cfg_sw;
+  while ((RCC->CFGR & RCC_CFGR_SWS) != (cfg_sw << 2))
+    ;
+}
+
+/*
+ * When HOW=0 or HOW=1, clock is PLL (72MHz).
+ * When HOW=2, clock will be HSI (8MHz) on sleep.
+ *
+ * With HSI clock, it can achieve lower power consumption.
+ *
+ * Implementation note: Deepsleep is only useful with RTC, Watch Dog,
+ * or WKUP pin.  We can't use deepsleep for USB, it never wakes up.
+ *
+ */
+void
+chx_sleep_mode (int how)
+{
+  if (how == 0 || how == 1)
+    configure_clock (RCC_CFGR_SW_PLL);
+
+  /* how == 2: Defer setting to 8MHz clock to the idle function */
+}
+
+void __attribute__((naked))
+chx_idle (void)
+{
+  int sleep_enabled;
+
+  for (;;)
+    {
+      asm ("ldr	%0, %1" : "=r" (sleep_enabled): "m" (chx_allow_sleep));
+      if (sleep_enabled)
+	{
+	  asm volatile ("cpsid	i" : : : "memory");
+	  if (sleep_enabled == 1)
+	    {
+	      /* Allow JTAG/SWD access on sleep.  */
+	      DBGMCU->CR |= DBG_SLEEP;
+	    }
+	  else if (sleep_enabled == 2)
+	    {
+	      DBGMCU->CR &= ~DBG_SLEEP; /* Disable HCLK on sleep */
+	      configure_clock (RCC_CFGR_SW_HCI);
+	    }
+	  asm volatile ("cpsie	i" : : : "memory");
+
+	  asm volatile ("wfi" : : : "memory");
+	  /* NOTE: it never comes here.  Don't add lines after this.  */
+	}
+    }
+}