samv7: add support for adjtime() interface

This commit adds deifiniton of get_timer_period() and adj_timer_period()
functions used by adjtime() interface.

Signed-off-by: Michal Lenc <[email protected]>

Author: michallenc

arch/arm/Kconfig

@@ -383,6 +383,7 @@ config ARCH_CHIP_SAMV7
 	select ARCH_HAVE_SPI_CS_CONTROL
 	select ARM_HAVE_MPU_UNIFIED
 	select ARMV7M_HAVE_STACKCHECK
+	select ARCH_HAVE_ADJTIME
 	---help---
 		Atmel SAMV7 (ARM Cortex-M7) architectures
 

arch/arm/src/samv7/sam_timerisr.c

@@ -93,6 +93,69 @@ static int sam_timerisr(int irq, uint32_t *regs, void *arg)
  * Public Functions
  ****************************************************************************/
 
+#ifdef CONFIG_CLOCK_ADJTIME
+
+/****************************************************************************
+ * Function:  up_adj_timer_period
+ *
+ * Description:
+ *   Adjusts timer period. This call is used when adjusting timer period as
+ *   defined in adjtime() function.
+ *
+ * Input Parameters:
+ *   period_inc_usec  - period adjustment in usec (reset to default value
+ *                      if 0)
+ *
+ ****************************************************************************/
+
+void up_adj_timer_period(long long period_inc_usec)
+{
+  uint32_t period;
+  long long period_inc;
+
+  if (period_inc_usec == 0)
+    {
+      period_inc = 0;
+    }
+  else
+    {
+      period_inc = (SAM_SYSTICK_CLOCK / 1000000) * period_inc_usec - 1;
+    }
+
+  period = SYSTICK_RELOAD + period_inc;
+
+  /* Check whether period is at maximum value. */
+
+  if (period > 0x00ffffff)
+    {
+      period = 0x00ffffff;
+    }
+
+  putreg32(period, NVIC_SYSTICK_RELOAD);
+}
+
+/****************************************************************************
+ * Function:  up_get_timer_period
+ *
+ * Description:
+ *   This function returns the timer period in usec.
+ *
+ * Input Parameters:
+ *   period_usec  - returned timer period in usec
+ *
+ ****************************************************************************/
+
+void up_get_timer_period(long long *period_usec)
+{
+  uint32_t period;
+
+  period = getreg32(NVIC_SYSTICK_RELOAD);
+
+  *period_usec = ((period + 1) / (SAM_SYSTICK_CLOCK / 1000000));
+}
+
+#endif
+
 /****************************************************************************
  * Function:  up_timer_initialize
  *