RP2040: Add basic RTC support

Author: pennam

targets/TARGET_RASPBERRYPI/TARGET_RP2040/pico-sdk/rp2_common/hardware_rtc/include/hardware/rtc.h

@@ -34,7 +34,7 @@ typedef void (*rtc_callback_t)(void);
 /*! \brief Initialise the RTC system
  *  \ingroup hardware_rtc
  */
-void rtc_init(void);
+void _rtc_init(void);
 
 /*! \brief Set the RTC to the specified time
  *  \ingroup hardware_rtc

targets/TARGET_RASPBERRYPI/TARGET_RP2040/pico-sdk/rp2_common/hardware_rtc/rtc.c

@@ -19,7 +19,7 @@ bool rtc_running(void) {
     return (rtc_hw->ctrl & RTC_CTRL_RTC_ACTIVE_BITS);
 }
 
-void rtc_init(void) {
+void _rtc_init(void) {
     // Get clk_rtc freq and make sure it is running
     uint rtc_freq = clock_get_hz(clk_rtc);
     assert(rtc_freq != 0);

targets/TARGET_RASPBERRYPI/TARGET_RP2040/rtc_api.c

@@ -0,0 +1,91 @@
+#if DEVICE_RTC
+
+#include "rtc_api.h"
+#include "hardware/rtc.h"
+#include "hardware/structs/rtc.h"
+#include "mbed_mktime.h"
+
+void rtc_init(void)
+{
+    _rtc_init();
+}
+
+void rtc_free(void)
+{
+   /* RTC clock can not be reset */
+}
+
+int rtc_isenabled(void)
+{
+    return rtc_running();
+}
+
+time_t rtc_read(void)
+{
+    struct tm timeinfo;
+    time_t t;
+    datetime_t date;
+    
+    if (!rtc_get_datetime(&date)) {
+        return 0;
+    } 
+
+    /* Setup a tm structure based on the RTC
+    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_yday     information is ignored by _rtc_maketime
+        tm_wday     information is ignored by _rtc_maketime
+        tm_isdst    information is ignored by _rtc_maketime
+    */
+    timeinfo.tm_year = date.year - 1900;
+    timeinfo.tm_mon = date.month - 1;
+    timeinfo.tm_mday = date.day;
+    timeinfo.tm_wday = date.dotw;
+    timeinfo.tm_hour = date.hour;
+    timeinfo.tm_min = date.min;
+    timeinfo.tm_sec = date.sec;
+
+    if (_rtc_maketime(&timeinfo, &t, RTC_4_YEAR_LEAP_YEAR_SUPPORT) == false) {
+        return 0;
+    }
+
+    return t;
+}
+
+void rtc_write(time_t t)
+{
+    struct tm timeinfo;
+    datetime_t date;
+
+    if (_rtc_localtime(t, &timeinfo, RTC_4_YEAR_LEAP_YEAR_SUPPORT) == false) {
+        return;
+    }
+    
+    /* Setup a datetime_t structure based on the RTC
+     struct datetime_t
+        year;     0..4095
+        month;    1..12, 1 is January
+        day;      1..28,29,30,31 depending on month
+        dotw;     0..6, 0 is Sunday
+        hour;     0..23
+        min;      0..59
+        sec;      0..59
+    */
+    date.year = timeinfo.tm_year + 1900;
+    date.month = timeinfo.tm_mon + 1;
+    date.day = timeinfo.tm_mday;
+    date.dotw = timeinfo.tm_wday;
+    date.hour = timeinfo.tm_hour;
+    date.min = timeinfo.tm_min;
+    date.sec = timeinfo.tm_sec;
+
+    rtc_set_datetime(&date);
+    return;
+}
+
+#endif // DEVICE_RTC

targets/targets.json

@@ -8600,6 +8600,7 @@
             "SERIAL",
             "SERIAL_FC",
             "SPI",
+            "RTC",
             "USTICKER",
             "WATCHDOG",
             "USBDEVICE",