Diff: targets/TARGET_NUVOTON/TARGET_M451/lp_ticker.c

Revision:

149:156823d33999

Child:

153:fa9ff456f731

diff -r 21d94c44109e -r 156823d33999 targets/TARGET_NUVOTON/TARGET_M451/lp_ticker.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/targets/TARGET_NUVOTON/TARGET_M451/lp_ticker.c	Fri Oct 28 11:17:30 2016 +0100
@@ -0,0 +1,226 @@
+/* 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 "lp_ticker_api.h"
+
+#if DEVICE_LOWPOWERTIMER
+
+#include "sleep_api.h"
+#include "nu_modutil.h"
+#include "nu_miscutil.h"
+#include "critical.h"
+
+// lp_ticker tick = us = timestamp
+#define US_PER_TICK             (1)
+#define US_PER_SEC              (1000 * 1000)
+
+#define US_PER_TMR2_INT         (US_PER_SEC * 10)
+#define TMR2_CLK_PER_SEC        (__LXT)
+#define TMR2_CLK_PER_TMR2_INT   ((uint32_t) ((uint64_t) US_PER_TMR2_INT * TMR2_CLK_PER_SEC / US_PER_SEC))
+#define TMR3_CLK_PER_SEC        (__LXT)
+
+static void tmr2_vec(void);
+static void tmr3_vec(void);
+static void lp_ticker_arm_cd(void);
+
+static int lp_ticker_inited = 0;
+static volatile uint32_t counter_major = 0;
+static volatile uint32_t cd_major_minor_clks = 0;
+static volatile uint32_t cd_minor_clks = 0;
+static volatile uint32_t wakeup_tick = (uint32_t) -1;
+
+// NOTE: To wake the system from power down mode, timer clock source must be ether LXT or LIRC.
+// NOTE: TIMER_2 for normal counting and TIMER_3 for scheduled wakeup
+static const struct nu_modinit_s timer2_modinit = {TIMER_2, TMR2_MODULE, CLK_CLKSEL1_TMR2SEL_LXT, 0, TMR2_RST, TMR2_IRQn, (void *) tmr2_vec};
+static const struct nu_modinit_s timer3_modinit = {TIMER_3, TMR3_MODULE, CLK_CLKSEL1_TMR3SEL_LXT, 0, TMR3_RST, TMR3_IRQn, (void *) tmr3_vec};
+
+#define TMR_CMP_MIN         2
+#define TMR_CMP_MAX         0xFFFFFFu
+
+void lp_ticker_init(void)
+{
+    if (lp_ticker_inited) {
+        return;
+    }
+    lp_ticker_inited = 1;
+    
+    counter_major = 0;
+    cd_major_minor_clks = 0;
+    cd_minor_clks = 0;
+    wakeup_tick = (uint32_t) -1;
+
+    // Reset module
+    SYS_ResetModule(timer2_modinit.rsetidx);
+    SYS_ResetModule(timer3_modinit.rsetidx);
+    
+    // Select IP clock source
+    CLK_SetModuleClock(timer2_modinit.clkidx, timer2_modinit.clksrc, timer2_modinit.clkdiv);
+    CLK_SetModuleClock(timer3_modinit.clkidx, timer3_modinit.clksrc, timer3_modinit.clkdiv);
+    // Enable IP clock
+    CLK_EnableModuleClock(timer2_modinit.clkidx);
+    CLK_EnableModuleClock(timer3_modinit.clkidx);
+
+    // Configure clock
+    uint32_t clk_timer2 = TIMER_GetModuleClock((TIMER_T *) NU_MODBASE(timer2_modinit.modname));
+    uint32_t prescale_timer2 = clk_timer2 / TMR2_CLK_PER_SEC - 1;
+    MBED_ASSERT((prescale_timer2 != (uint32_t) -1) && prescale_timer2 <= 127);
+    MBED_ASSERT((clk_timer2 % TMR2_CLK_PER_SEC) == 0);
+    uint32_t cmp_timer2 = TMR2_CLK_PER_TMR2_INT;
+    MBED_ASSERT(cmp_timer2 >= TMR_CMP_MIN && cmp_timer2 <= TMR_CMP_MAX);
+    // Continuous mode
+    // NOTE: TIMER_CTL_CNTDATEN_Msk exists in NUC472, but not in M451. In M451, TIMER_CNT is updated continuously by default.
+    ((TIMER_T *) NU_MODBASE(timer2_modinit.modname))->CTL = TIMER_PERIODIC_MODE | prescale_timer2/* | TIMER_CTL_CNTDATEN_Msk*/;
+    ((TIMER_T *) NU_MODBASE(timer2_modinit.modname))->CMP = cmp_timer2;
+    
+    // Set vector
+    NVIC_SetVector(timer2_modinit.irq_n, (uint32_t) timer2_modinit.var);
+    NVIC_SetVector(timer3_modinit.irq_n, (uint32_t) timer3_modinit.var);
+    
+    NVIC_EnableIRQ(timer2_modinit.irq_n);
+    NVIC_EnableIRQ(timer3_modinit.irq_n);
+    
+    TIMER_EnableInt((TIMER_T *) NU_MODBASE(timer2_modinit.modname));
+    TIMER_EnableWakeup((TIMER_T *) NU_MODBASE(timer2_modinit.modname));
+    
+    // Schedule wakeup to match semantics of lp_ticker_get_compare_match()
+    lp_ticker_set_interrupt(wakeup_tick);
+    
+    // Start timer
+    TIMER_Start((TIMER_T *) NU_MODBASE(timer2_modinit.modname));
+}
+
+timestamp_t lp_ticker_read()
+{    
+    if (! lp_ticker_inited) {
+        lp_ticker_init();
+    }
+    
+    TIMER_T * timer2_base = (TIMER_T *) NU_MODBASE(timer2_modinit.modname);
+    
+    do {
+        uint64_t major_minor_clks;
+        uint32_t minor_clks;
+        
+        // NOTE: As TIMER_CNT = TIMER_CMP and counter_major has increased by one, TIMER_CNT doesn't change to 0 for one tick time.
+        // NOTE: As TIMER_CNT = TIMER_CMP or TIMER_CNT = 0, counter_major (ISR) may not sync with TIMER_CNT. So skip and fetch stable one at the cost of 1 clock delay on this read.
+        do {
+            core_util_critical_section_enter();
+        
+            // NOTE: Order of reading minor_us/carry here is significant.
+            minor_clks = TIMER_GetCounter(timer2_base);
+            uint32_t carry = (timer2_base->INTSTS & TIMER_INTSTS_TIF_Msk) ? 1 : 0;
+            // When TIMER_CNT approaches TIMER_CMP and will wrap soon, we may get carry but TIMER_CNT not wrapped. Hanlde carefully carry == 1 && TIMER_CNT is near TIMER_CMP.
+            if (carry && minor_clks > (TMR2_CLK_PER_TMR2_INT / 2)) {
+                major_minor_clks = (counter_major + 1) * TMR2_CLK_PER_TMR2_INT;
+            }
+            else {
+                major_minor_clks = (counter_major + carry) * TMR2_CLK_PER_TMR2_INT + minor_clks;
+            }
+            
+            core_util_critical_section_exit();
+        }
+        while (minor_clks == 0 || minor_clks == TMR2_CLK_PER_TMR2_INT);
+
+        // Add power-down compensation
+        return ((uint64_t) major_minor_clks * US_PER_SEC / TMR3_CLK_PER_SEC / US_PER_TICK);
+    }
+    while (0);
+}
+
+void lp_ticker_set_interrupt(timestamp_t timestamp)
+{
+    uint32_t now = lp_ticker_read();
+    wakeup_tick = timestamp;
+    
+    TIMER_Stop((TIMER_T *) NU_MODBASE(timer3_modinit.modname));
+    
+    /**
+     * FIXME: Scheduled alarm may go off incorrectly due to wrap around.
+     * Conditions in which delta is negative:
+     * 1. Wrap around
+     * 2. Newly scheduled alarm is behind now
+     */ 
+    //int delta = (timestamp > now) ? (timestamp - now) : (uint32_t) ((uint64_t) timestamp + 0xFFFFFFFFu - now);
+    int delta = (int) (timestamp - now);
+    if (delta > 0) {
+        cd_major_minor_clks = (uint64_t) delta * US_PER_TICK * TMR3_CLK_PER_SEC / US_PER_SEC;
+        lp_ticker_arm_cd();
+    }
+    else {
+        cd_major_minor_clks = cd_minor_clks = 0;
+        /**
+         * This event was in the past. Set the interrupt as pending, but don't process it here.
+         * This prevents a recurive loop under heavy load which can lead to a stack overflow.
+         */  
+        NVIC_SetPendingIRQ(timer3_modinit.irq_n);
+    }
+}
+
+void lp_ticker_disable_interrupt(void)
+{
+    TIMER_DisableInt((TIMER_T *) NU_MODBASE(timer3_modinit.modname));
+}
+
+void lp_ticker_clear_interrupt(void)
+{
+    TIMER_ClearIntFlag((TIMER_T *) NU_MODBASE(timer3_modinit.modname));
+}
+
+static void tmr2_vec(void)
+{
+    TIMER_ClearIntFlag((TIMER_T *) NU_MODBASE(timer2_modinit.modname));
+    TIMER_ClearWakeupFlag((TIMER_T *) NU_MODBASE(timer2_modinit.modname));
+    counter_major ++;
+}
+
+static void tmr3_vec(void)
+{
+    TIMER_ClearIntFlag((TIMER_T *) NU_MODBASE(timer3_modinit.modname));
+    TIMER_ClearWakeupFlag((TIMER_T *) NU_MODBASE(timer3_modinit.modname));
+    cd_major_minor_clks = (cd_major_minor_clks > cd_minor_clks) ? (cd_major_minor_clks - cd_minor_clks) : 0;
+    if (cd_major_minor_clks == 0) {
+        // NOTE: lp_ticker_set_interrupt() may get called in lp_ticker_irq_handler();
+        lp_ticker_irq_handler();
+    }
+    else {
+        lp_ticker_arm_cd();
+    }
+}
+
+static void lp_ticker_arm_cd(void)
+{
+    TIMER_T * timer3_base = (TIMER_T *) NU_MODBASE(timer3_modinit.modname);
+    
+    // Reset 8-bit PSC counter, 24-bit up counter value and CNTEN bit
+    timer3_base->CTL |= TIMER_CTL_RSTCNT_Msk;
+    // One-shot mode, Clock = 1 KHz 
+    uint32_t clk_timer3 = TIMER_GetModuleClock((TIMER_T *) NU_MODBASE(timer3_modinit.modname));
+    uint32_t prescale_timer3 = clk_timer3 / TMR3_CLK_PER_SEC - 1;
+    MBED_ASSERT((prescale_timer3 != (uint32_t) -1) && prescale_timer3 <= 127);
+    MBED_ASSERT((clk_timer3 % TMR3_CLK_PER_SEC) == 0);
+    // NOTE: TIMER_CTL_CNTDATEN_Msk exists in NUC472, but not in M451. In M451, TIMER_CNT is updated continuously by default.
+    timer3_base->CTL &= ~(TIMER_CTL_OPMODE_Msk | TIMER_CTL_PSC_Msk/* | TIMER_CTL_CNTDATEN_Msk*/);
+    timer3_base->CTL |= TIMER_ONESHOT_MODE | prescale_timer3/* | TIMER_CTL_CNTDATEN_Msk*/;
+    
+    cd_minor_clks = cd_major_minor_clks;
+    cd_minor_clks = NU_CLAMP(cd_minor_clks, TMR_CMP_MIN, TMR_CMP_MAX);
+    timer3_base->CMP = cd_minor_clks;
+    
+    TIMER_EnableInt(timer3_base);
+    TIMER_EnableWakeup((TIMER_T *) NU_MODBASE(timer3_modinit.modname));
+    TIMER_Start(timer3_base);
+}
+#endif