cpu/samd21: add rtc periph implementation

boards/samr21-xpro/Makefile.features

@@ -1 +1 @@
-FEATURES_PROVIDED += periph_gpio cpp periph_uart periph_timer
+FEATURES_PROVIDED += periph_gpio cpp periph_uart periph_timer periph_rtc

boards/samr21-xpro/include/periph_conf.h

@@ -91,6 +91,14 @@ extern "C" {
 #define RANDOM_NUMOF        (0U)
 /** @} */
 
+/**
+ * @name RTC configuration
+ * @{
+ */
+#define RTC_NUMOF           (1U)
+#define RTC_DEV             RTC->MODE2
+/** @} */
+
 /**
  * @name GPIO configuration
  * @{

cpu/samd21/periph/rtc.c

@@ -0,0 +1,201 @@
+/*
+ * Copyright (C) 2014 Baptiste CLENET
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @ingroup     cpu_samd21
+ * @{
+ * @file
+ * @brief       Low-level RTC driver implementation
+ * @author      Baptiste Clenet <baptiste.clenet@xsoen.com>
+ * @}
+ */
+
+#include <time.h>
+#include "cpu.h"
+#include "periph/rtc.h"
+#include "periph_conf.h"
+#include "sched.h"
+#include "thread.h"
+
+/* guard file in case no RTC device was specified */
+#if RTC_NUMOF
+
+typedef struct {
+    rtc_alarm_cb_t cb;        /**< callback called from RTC interrupt */
+    void *arg;                /**< argument passed to the callback */
+} rtc_state_t;
+
+static rtc_state_t rtc_callback;
+
+static uint16_t reference_year = 100;
+
+void rtc_init(void)
+{
+    RtcMode2 *rtcMode2 = &(RTC_DEV);
+
+    /* Turn on power manager for RTC */
+    PM->APBAMASK.reg |= PM_APBAMASK_RTC;
+
+    SYSCTRL->OSC32K.bit.ENABLE = 0;
+    SYSCTRL->OSC32K.bit.ONDEMAND = 1;
+    SYSCTRL->OSC32K.bit.RUNSTDBY = 0;
+    SYSCTRL->OSC32K.bit.EN1K = 1;
+    SYSCTRL->OSC32K.bit.EN32K = 1;
+    SYSCTRL->OSC32K.bit.ENABLE = 1;
+
+    /* Setup clock GCLK2 */
+    GCLK->GENDIV.reg = GCLK_GENDIV_ID(2)|GCLK_GENDIV_DIV(4);
+    while (GCLK->STATUS.reg & GCLK_STATUS_SYNCBUSY);
+    GCLK->GENCTRL.reg = (GCLK_GENCTRL_GENEN | GCLK_GENCTRL_SRC_OSC32K | GCLK_GENCTRL_ID(2) | GCLK_GENCTRL_DIVSEL );
+    while (GCLK->STATUS.reg & GCLK_STATUS_SYNCBUSY);
+    GCLK->CLKCTRL.reg = (uint32_t)((GCLK_CLKCTRL_CLKEN | GCLK_CLKCTRL_GEN_GCLK2 | (RTC_GCLK_ID << GCLK_CLKCTRL_ID_Pos)));
+    while (GCLK->STATUS.bit.SYNCBUSY);
+
+    /* DISABLE RTC MASTER */
+    while(rtcMode2->STATUS.reg & RTC_STATUS_SYNCBUSY);
+    rtc_poweroff();
+
+    /* Reset RTC */
+    while(rtcMode2->STATUS.bit.SYNCBUSY);
+    rtcMode2->CTRL.reg= RTC_MODE2_CTRL_SWRST;
+    while(rtcMode2->STATUS.bit.SYNCBUSY);
+
+    /* RTC config with RTC_MODE2_CTRL_CLKREP = 0 (24h) */
+    rtcMode2->CTRL.reg = RTC_MODE2_CTRL_PRESCALER_DIV1024|RTC_MODE2_CTRL_MODE_CLOCK;
+    while(rtcMode2->STATUS.bit.SYNCBUSY);
+    rtcMode2->INTENSET.reg = RTC_MODE2_INTENSET_OVF;
+    while(rtcMode2->STATUS.bit.SYNCBUSY);
+    rtc_poweron();
+}
+
+int rtc_set_time(struct tm *time)
+{
+    RtcMode2 *rtcMode2 = &(RTC_DEV);
+    if((time->tm_year < reference_year) || (time->tm_year > reference_year + 63)){
+        return -1;
+    }
+    else{
+        rtcMode2->CLOCK.reg = RTC_MODE2_CLOCK_YEAR(time->tm_year - reference_year)
+                | RTC_MODE2_CLOCK_MONTH(time->tm_mon + 1)
+                | RTC_MODE2_CLOCK_DAY(time->tm_mday)
+                | RTC_MODE2_CLOCK_HOUR(time->tm_hour)
+                | RTC_MODE2_CLOCK_MINUTE(time->tm_min)
+                | RTC_MODE2_CLOCK_SECOND(time->tm_sec);
+    }
+    while(rtcMode2->STATUS.bit.SYNCBUSY);
+    return 0;
+}
+
+int rtc_get_time(struct tm *time)
+{
+    RtcMode2 *rtcMode2 = &(RTC_DEV);
+    time->tm_year = rtcMode2->CLOCK.bit.YEAR + reference_year;
+    if((time->tm_year < reference_year) || (time->tm_year > (reference_year + 63))){
+            return -1;
+        }
+    time->tm_mon = rtcMode2->CLOCK.bit.MONTH - 1;
+    time->tm_mday = rtcMode2->CLOCK.bit.DAY;
+    time->tm_hour = rtcMode2->CLOCK.bit.HOUR;
+    time->tm_min = rtcMode2->CLOCK.bit.MINUTE;
+    time->tm_sec = rtcMode2->CLOCK.bit.SECOND;
+    while(rtcMode2->STATUS.bit.SYNCBUSY);
+    return 0;
+}
+
+int rtc_set_alarm(struct tm *time, rtc_alarm_cb_t cb, void *arg)
+{
+    RtcMode2 *rtcMode2 = &(RTC_DEV);
+    rtc_clear_alarm();
+    if((time->tm_year < reference_year) || (time->tm_year > (reference_year + 63))){
+        return -2;
+    }
+    else{
+        rtcMode2->Mode2Alarm[0].ALARM.reg = RTC_MODE2_ALARM_YEAR(time->tm_year - reference_year)
+                | RTC_MODE2_ALARM_MONTH(time->tm_mon + 1)
+                | RTC_MODE2_ALARM_DAY(time->tm_mday)
+                | RTC_MODE2_ALARM_HOUR(time->tm_hour)
+                | RTC_MODE2_ALARM_MINUTE(time->tm_min)
+                | RTC_MODE2_ALARM_SECOND(time->tm_sec);
+        rtcMode2->Mode2Alarm[0].MASK.reg = RTC_MODE2_MASK_SEL(6);
+    }
+    while(rtcMode2->STATUS.bit.SYNCBUSY);
+
+    /* Setup interrupt */
+    NVIC_SetPriority(RTC_IRQn, 10);
+    NVIC_EnableIRQ(RTC_IRQn);
+
+    /* Enable IRQ */
+    rtc_callback.cb = cb;
+    rtc_callback.arg = arg;
+    rtcMode2->INTFLAG.reg = RTC_MODE2_INTFLAG_ALARM0;
+    while(rtcMode2->STATUS.bit.SYNCBUSY);
+    rtcMode2->INTENSET.reg = RTC_MODE2_INTENSET_ALARM0;
+    while(rtcMode2->STATUS.bit.SYNCBUSY);
+
+    return 0;
+}
+
+int rtc_get_alarm(struct tm *time)
+{
+    RtcMode2 *rtcMode2 = &(RTC_DEV);
+    time->tm_year = rtcMode2->Mode2Alarm[0].ALARM.bit.YEAR + reference_year;
+    if((time->tm_year < reference_year) || (time->tm_year > (reference_year + 63))){
+            return -1;
+        }
+    time->tm_mon = rtcMode2->CLOCK.bit.MONTH - 1;
+    time->tm_mday = rtcMode2->CLOCK.bit.DAY;
+    time->tm_hour = rtcMode2->CLOCK.bit.HOUR;
+    time->tm_min = rtcMode2->CLOCK.bit.MINUTE;
+    time->tm_sec = rtcMode2->CLOCK.bit.SECOND;
+    while(rtcMode2->STATUS.bit.SYNCBUSY);
+    return 0;
+}
+
+void rtc_clear_alarm(void)
+{
+    RtcMode2 *rtcMode2 = &(RTC_DEV);
+    /* Disable IRQ */
+    rtcMode2->INTENCLR.reg = RTC_MODE2_INTENCLR_ALARM0;
+    rtc_callback.cb = NULL;
+    rtc_callback.arg = NULL;
+}
+
+void rtc_poweron(void)
+{
+    RtcMode2 *rtcMode2 = &(RTC_DEV);
+    rtcMode2->CTRL.bit.ENABLE = 1;
+    while(rtcMode2->STATUS.bit.SYNCBUSY);
+}
+
+void rtc_poweroff(void)
+{
+    RtcMode2 *rtcMode2 = &(RTC_DEV);
+    rtcMode2->CTRL.bit.ENABLE = 0;
+    while(rtcMode2->STATUS.bit.SYNCBUSY);
+}
+
+void isr_rtc(void)
+{
+    RtcMode2 *rtcMode2 = &(RTC_DEV);
+    uint16_t status = rtcMode2->INTFLAG.reg;
+    if(status & RTC_MODE2_INTFLAG_ALARM0){
+        rtc_callback.cb(rtc_callback.arg);
+        rtcMode2->INTFLAG.reg = RTC_MODE2_INTFLAG_ALARM0;
+    }
+    if(status & RTC_MODE2_INTFLAG_OVF){
+        /* At 1Hz, RTC goes till 63 years (2^5, see 17.8.22 in datasheet)
+        * Start RTC again with reference_year 64 years more (Be careful with alarm set) */
+        reference_year += 64;
+        rtcMode2->INTFLAG.reg = RTC_MODE2_INTFLAG_OVF;
+    }
+    if (sched_context_switch_request) {
+        thread_yield();
+    }
+}
+
+#endif /* RTC_NUMOF */