Diff: targets/TARGET_Maxim/TARGET_MAX32625/rtc_api.c

Revision:

150:02e0a0aed4ec

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/targets/TARGET_Maxim/TARGET_MAX32625/rtc_api.c	Tue Nov 08 17:45:16 2016 +0000
@@ -0,0 +1,253 @@
+/*******************************************************************************
+ * Copyright (C) 2016 Maxim Integrated Products, Inc., All Rights Reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL MAXIM INTEGRATED BE LIABLE FOR ANY CLAIM, DAMAGES
+ * OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * Except as contained in this notice, the name of Maxim Integrated
+ * Products, Inc. shall not be used except as stated in the Maxim Integrated
+ * Products, Inc. Branding Policy.
+ *
+ * The mere transfer of this software does not imply any licenses
+ * of trade secrets, proprietary technology, copyrights, patents,
+ * trademarks, maskwork rights, or any other form of intellectual
+ * property whatsoever. Maxim Integrated Products, Inc. retains all
+ * ownership rights.
+ *******************************************************************************
+ */
+
+#include "rtc_api.h"
+#include "lp_ticker_api.h"
+#include "rtc.h"
+#include "lp.h"
+
+#define PRESCALE_VAL    RTC_PRESCALE_DIV_2_0    // Set the divider for the 4kHz clock
+#define SHIFT_AMT       (RTC_PRESCALE_DIV_2_12 - PRESCALE_VAL)
+
+#define WINDOW          1000
+
+static int rtc_inited = 0;
+static volatile uint32_t overflow_cnt = 0;
+
+static uint64_t rtc_read64(void);
+
+//******************************************************************************
+static void overflow_handler(void)
+{
+    overflow_cnt++;
+    RTC_ClearFlags(MXC_F_RTC_FLAGS_ASYNC_CLR_FLAGS);
+}
+
+//******************************************************************************
+void rtc_init(void)
+{
+    if (rtc_inited) {
+        return;
+    }
+    rtc_inited = 1;
+
+    overflow_cnt = 0;
+
+    /* Enable power for RTC for all LPx states */
+    MXC_PWRSEQ->reg0 |= (MXC_F_PWRSEQ_REG0_PWR_RTCEN_RUN |
+                         MXC_F_PWRSEQ_REG0_PWR_RTCEN_SLP);
+
+    /* Enable clock to synchronizers */
+    CLKMAN_SetClkScale(CLKMAN_CLK_SYNC, CLKMAN_SCALE_DIV_1);
+
+    // Prepare interrupt handlers
+    NVIC_SetVector(RTC0_IRQn, (uint32_t)lp_ticker_irq_handler);
+    NVIC_EnableIRQ(RTC0_IRQn);
+    NVIC_SetVector(RTC3_IRQn, (uint32_t)overflow_handler);
+    NVIC_EnableIRQ(RTC3_IRQn);
+
+    // Enable wakeup on RTC rollover
+    LP_ConfigRTCWakeUp(0, 0, 0, 1);
+
+    /* RTC registers are only reset on a power cycle. Do not reconfigure the RTC
+     * if it is already running.
+     */
+    if (!RTC_IsActive()) {
+        rtc_cfg_t cfg = {0};
+        cfg.prescaler = PRESCALE_VAL;
+        cfg.snoozeMode = RTC_SNOOZE_DISABLE;
+
+        int retval = RTC_Init(&cfg);
+        MBED_ASSERT(retval == E_NO_ERROR);
+
+        RTC_EnableINT(MXC_F_RTC_FLAGS_OVERFLOW);
+        RTC_Start();
+    }
+}
+
+//******************************************************************************
+void lp_ticker_init(void)
+{
+    rtc_init();
+}
+
+//******************************************************************************
+void rtc_free(void)
+{
+    if (RTC_IsActive()) {
+        // Clear and disable RTC
+        MXC_RTCTMR->ctrl |= MXC_F_RTC_CTRL_CLEAR;
+        RTC_Stop();
+    }
+}
+
+//******************************************************************************
+int rtc_isenabled(void)
+{
+    return RTC_IsActive();
+}
+
+//******************************************************************************
+time_t rtc_read(void)
+{
+    uint32_t ovf_cnt_1, ovf_cnt_2, timer_cnt;
+    uint32_t ovf1, ovf2;
+
+    // Make sure RTC is setup before trying to read
+    if (!rtc_inited) {
+        rtc_init();
+    }
+
+    // Ensure coherency between overflow_cnt and timer
+    do {
+        ovf_cnt_1 = overflow_cnt;
+        ovf1 = RTC_GetFlags() & MXC_F_RTC_FLAGS_OVERFLOW;
+        timer_cnt = RTC_GetCount();
+        ovf2 = RTC_GetFlags() & MXC_F_RTC_FLAGS_OVERFLOW;
+        ovf_cnt_2 = overflow_cnt;
+    } while ((ovf_cnt_1 != ovf_cnt_2) || (ovf1 != ovf2));
+
+    // Account for an unserviced interrupt
+    if (ovf1) {
+        ovf_cnt_1++;
+    }
+
+    return (timer_cnt >> SHIFT_AMT) + (ovf_cnt_1 << (32 - SHIFT_AMT));
+}
+
+//******************************************************************************
+static uint64_t rtc_read64(void)
+{
+    uint32_t ovf_cnt_1, ovf_cnt_2, timer_cnt;
+    uint32_t ovf1, ovf2;
+    uint64_t current_us;
+
+    // Make sure RTC is setup before trying to read
+    if (!rtc_inited) {
+        rtc_init();
+    }
+
+    // Ensure coherency between overflow_cnt and timer
+    do {
+        ovf_cnt_1 = overflow_cnt;
+        ovf1 = RTC_GetFlags() & MXC_F_RTC_FLAGS_OVERFLOW;
+        timer_cnt = RTC_GetCount();
+        ovf2 = RTC_GetFlags() & MXC_F_RTC_FLAGS_OVERFLOW;
+        ovf_cnt_2 = overflow_cnt;
+    } while ((ovf_cnt_1 != ovf_cnt_2) || (ovf1 != ovf2));
+
+    // Account for an unserviced interrupt
+    if (ovf1) {
+        ovf_cnt_1++;
+    }
+
+    current_us = (((uint64_t)timer_cnt * 1000000) >> SHIFT_AMT) + (((uint64_t)ovf_cnt_1 * 1000000) << (32 - SHIFT_AMT));
+
+    return current_us;
+}
+
+//******************************************************************************
+void rtc_write(time_t t)
+{
+    // Make sure RTC is setup before accessing
+    if (!rtc_inited) {
+        rtc_init();
+    }
+
+    RTC_Stop();
+    RTC_SetCount(t << SHIFT_AMT);
+    overflow_cnt = t >> (32 - SHIFT_AMT);
+    RTC_Start();
+}
+
+//******************************************************************************
+void lp_ticker_set_interrupt(timestamp_t timestamp)
+{
+    uint32_t comp_value;
+    uint64_t curr_ts64;
+    uint64_t ts64;
+
+    // Note: interrupts are disabled before this function is called.
+
+    // Disable the alarm while it is prepared
+    RTC_DisableINT(MXC_F_RTC_INTEN_COMP0);
+
+    curr_ts64 = rtc_read64();
+    ts64 = (uint64_t)timestamp | (curr_ts64 & 0xFFFFFFFF00000000ULL);
+
+    // If this event is older than a recent window, it must be in the future
+    if ((ts64 < (curr_ts64 - WINDOW)) && ((curr_ts64 - WINDOW) < curr_ts64)) {
+        ts64 += 0x100000000ULL;
+    }
+
+    uint32_t timer = RTC_GetCount();
+    if (ts64 <= curr_ts64) {
+        // This event has already occurred. Set the alarm to expire immediately.
+        comp_value = timer + 1;
+    } else {
+        comp_value = (ts64 << SHIFT_AMT) / 1000000;
+    }
+
+    // Ensure that the compare value is far enough in the future to guarantee the interrupt occurs.
+    if ((comp_value < (timer + 2)) && (comp_value > (timer - 10))) {
+        comp_value = timer + 2;
+    }
+
+    MXC_RTCTMR->comp[0] = comp_value;
+    MXC_RTCTMR->flags = MXC_F_RTC_FLAGS_ASYNC_CLR_FLAGS;
+    RTC_EnableINT(MXC_F_RTC_INTEN_COMP0);
+
+    // Enable wakeup from RTC
+    LP_ConfigRTCWakeUp(1, 0, 0, 1);
+
+    // Wait for pending transactions
+    while (MXC_RTCTMR->ctrl & MXC_F_RTC_CTRL_PENDING);
+}
+
+//******************************************************************************
+inline void lp_ticker_disable_interrupt(void)
+{
+    RTC_DisableINT(MXC_F_RTC_INTEN_COMP0);
+}
+
+//******************************************************************************
+inline void lp_ticker_clear_interrupt(void)
+{
+    RTC_ClearFlags(MXC_F_RTC_FLAGS_ASYNC_CLR_FLAGS);
+}
+
+//******************************************************************************
+inline uint32_t lp_ticker_read(void)
+{
+    return rtc_read64();
+}