Diff: mbed-os/targets/TARGET_NUVOTON/TARGET_M480/rtc_api.c

Revision:

0:8fdf9a60065b

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed-os/targets/TARGET_NUVOTON/TARGET_M480/rtc_api.c	Wed Oct 10 00:33:53 2018 +0000
@@ -0,0 +1,211 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2015-2016 Nuvoton
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "rtc_api.h"
+
+#if DEVICE_RTC
+
+#include "mbed_wait_api.h"
+#include "mbed_error.h"
+#include "nu_modutil.h"
+#include "nu_miscutil.h"
+#include "mbed_mktime.h"
+
+/* Micro seconds per second */
+#define NU_US_PER_SEC               1000000
+/* Timer clock per second
+ *
+ * NOTE: This dependents on real hardware.
+ */
+#define NU_RTCCLK_PER_SEC           ((CLK->CLKSEL3 & CLK_CLKSEL3_SC0SEL_Msk) ? __LIRC : __LXT)
+
+/* Strategy for implementation of RTC HAL
+ *
+ * H/W RTC just supports year range 2000~2099, which cannot fully cover POSIX time (starting since 2970)
+ * and date time of struct TM (starting since 1900).
+ *
+ * To conquer the difficulty, we don't use H/W RTC to keep real date time. Instead, we use it to keep
+ * elapsed time in seconds since one reference time point. The strategy would be:
+ *
+ * 1. Choose DATETIME_HWRTC_ORIGIN (00:00:00 UTC, Saturday, 1 January 2000) as reference time point of H/W RTC.
+ * 2. t_hwrtc_origin = DATETIME_HWRTC_ORIGIN in POSIX time
+ * 3. t_hwrtc_elapsed = t_hwrtc_origin + elapsed time since t_hwrtc_origin
+ * 4. t_write = POSIX time set by rtc_write().
+ * 5. t_present = rtc_read() = t_write + (t_hwrtc_elapsed - t_hwrtc_origin)
+ *
+ * 1900
+ * |---------------------------------------------------------------------------------|
+ *           1970    t_write           t_present
+ * |---------|-------|-----------------|---------------------------------------------|
+ * 
+ * 2000 
+ * |-----------------|---------------------------------------------------------------|
+ * t_hwrtc_origin    t_hwrtc_elapsed
+ *
+ */
+/* Start year of struct TM*/
+#define NU_TM_YEAR0         1900
+/* Start year of POSIX time (set_time()/time()) */
+#define NU_POSIX_YEAR0      1970
+/* Start year of H/W RTC */
+#define NU_HWRTC_YEAR0      2000
+
+/* RTC H/W origin time: 00:00:00 UTC, Saturday, 1 January 2000 */
+static const S_RTC_TIME_DATA_T DATETIME_HWRTC_ORIGIN = {
+    2000,           /* Year value, range between 2000 ~ 2099 */
+    1,              /* Month value, range between 1 ~ 12 */
+    1,              /* Day value, range between 1 ~ 31 */
+    RTC_SATURDAY,   /* Day of the week */
+    0,              /* Hour value, range between 0 ~ 23 */
+    0,              /* Minute value, range between 0 ~ 59 */
+    0,              /* Second value, range between 0 ~ 59 */
+    RTC_CLOCK_24,   /* 12-Hour (RTC_CLOCK_12) / 24-Hour (RTC_CLOCK_24) */
+    0               /* RTC_AM / RTC_PM (used only for 12-Hour) */
+};
+/* t_hwrtc_origin initialized or not? */
+static bool t_hwrtc_origin_inited = 0;
+/* POSIX time of DATETIME_HWRTC_ORIGIN (since 00:00:00 UTC, Thursday, 1 January 1970) */
+static time_t t_hwrtc_origin = 0;
+/* POSIX time set by rtc_write() */
+static time_t t_write = 0;
+/* Convert date time from H/W RTC to struct TM */
+static void rtc_convert_datetime_hwrtc_to_tm(struct tm *datetime_tm, const S_RTC_TIME_DATA_T *datetime_hwrtc);
+
+static const struct nu_modinit_s rtc_modinit = {RTC_0, RTC_MODULE, 0, 0, 0, RTC_IRQn, NULL};
+
+void rtc_init(void)
+{
+    if (rtc_isenabled()) {
+        return;
+    }
+
+    RTC_Open(NULL);
+
+    /* POSIX time origin (00:00:00 UTC, Thursday, 1 January 1970) */
+    rtc_write(0);
+}
+
+void rtc_free(void)
+{
+    CLK_DisableModuleClock(rtc_modinit.clkidx);
+}
+
+int rtc_isenabled(void)
+{
+    // NOTE: To access (RTC) registers, clock must be enabled first.
+    if (! (CLK->APBCLK0 & CLK_APBCLK0_RTCCKEN_Msk)) {
+        // Enable IP clock
+        CLK_EnableModuleClock(rtc_modinit.clkidx);
+    }
+
+    // NOTE: Check RTC Init Active flag to support crossing reset cycle.
+    return !! (RTC->INIT & RTC_INIT_ACTIVE_Msk);
+}
+
+time_t rtc_read(void)
+{
+    /* NOTE: After boot, RTC time registers are not synced immediately, about 1 sec latency.
+     *       RTC time got (through RTC_GetDateAndTime()) in this sec would be last-synced and incorrect.
+     *       NUC472/M453: Known issue
+     *       M487: Fixed
+     */
+    if (! rtc_isenabled()) {
+        rtc_init();
+    }
+
+    /* Used for intermediary between date time of H/W RTC and POSIX time */
+    struct tm datetime_tm;
+
+    if (! t_hwrtc_origin_inited) {
+        t_hwrtc_origin_inited = 1;
+        
+        /* Convert date time from H/W RTC to struct TM */     
+        rtc_convert_datetime_hwrtc_to_tm(&datetime_tm, &DATETIME_HWRTC_ORIGIN);
+        /* Convert date time of struct TM to POSIX time */
+        if (! _rtc_maketime(&datetime_tm, &t_hwrtc_origin, RTC_FULL_LEAP_YEAR_SUPPORT)) {
+            return 0;
+        }
+
+        /* Load t_write from RTC spare register to cross reset cycle */
+        RTC_WaitAccessEnable();
+        RTC_EnableSpareAccess();
+        RTC_WaitAccessEnable();
+        t_write = RTC_READ_SPARE_REGISTER(0);
+    }
+
+    S_RTC_TIME_DATA_T hwrtc_datetime_2K_present;
+    RTC_WaitAccessEnable();
+    RTC_GetDateAndTime(&hwrtc_datetime_2K_present);
+    /* Convert date time from H/W RTC to struct TM */
+    rtc_convert_datetime_hwrtc_to_tm(&datetime_tm, &hwrtc_datetime_2K_present);
+    /* Convert date time of struct TM to POSIX time */
+    time_t t_hwrtc_elapsed;
+    if (! _rtc_maketime(&datetime_tm, &t_hwrtc_elapsed, RTC_FULL_LEAP_YEAR_SUPPORT)) {
+        return 0;
+    }
+
+    /* Present time in POSIX time */
+    time_t t_present = t_write + (t_hwrtc_elapsed - t_hwrtc_origin);
+    return t_present;
+}
+
+void rtc_write(time_t t)
+{
+    if (! rtc_isenabled()) {
+        rtc_init();
+    }
+
+    t_write = t;
+
+    /* Store t_write to RTC spare register to cross reset cycle */
+    RTC_WaitAccessEnable();
+    RTC_EnableSpareAccess();
+    RTC_WaitAccessEnable();
+    RTC_WRITE_SPARE_REGISTER(0, t_write);
+
+    RTC_WaitAccessEnable();
+    RTC_SetDateAndTime((S_RTC_TIME_DATA_T *) &DATETIME_HWRTC_ORIGIN);
+    /* NOTE: When engine is clocked by low power clock source (LXT/LIRC), we need to wait for 3 engine clocks. */
+    wait_us((NU_US_PER_SEC / NU_RTCCLK_PER_SEC) * 3);
+}
+
+/*
+ struct tm
+   tm_sec      seconds after the minute 0-61
+   tm_min      minutes after the hour 0-59
+   tm_hour     hours since midnight 0-23
+   tm_mday     day of the month 1-31
+   tm_mon      months since January 0-11
+   tm_year     years since 1900
+   tm_wday     days since Sunday 0-6
+   tm_yday     days since January 1 0-365
+   tm_isdst    Daylight Saving Time flag
+*/
+static void rtc_convert_datetime_hwrtc_to_tm(struct tm *datetime_tm, const S_RTC_TIME_DATA_T *datetime_hwrtc)
+{
+    datetime_tm->tm_year = datetime_hwrtc->u32Year - NU_TM_YEAR0;
+    datetime_tm->tm_mon  = datetime_hwrtc->u32Month - 1;
+    datetime_tm->tm_mday = datetime_hwrtc->u32Day;
+    datetime_tm->tm_wday = datetime_hwrtc->u32DayOfWeek;
+    datetime_tm->tm_hour = datetime_hwrtc->u32Hour;
+    if (datetime_hwrtc->u32TimeScale == RTC_CLOCK_12 && datetime_hwrtc->u32AmPm == RTC_PM) {
+        datetime_tm->tm_hour += 12;
+    }
+    datetime_tm->tm_min  = datetime_hwrtc->u32Minute;
+    datetime_tm->tm_sec  = datetime_hwrtc->u32Second;
+}
+
+#endif