Diff: targets/TARGET_NUVOTON/TARGET_M480/us_ticker.c

Revision:

173:7d866c31b3c5

Child:

180:b0033dcd6934

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/targets/TARGET_NUVOTON/TARGET_M480/us_ticker.c	Thu Aug 31 17:27:04 2017 +0100
@@ -0,0 +1,214 @@
+/* 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 "us_ticker_api.h"
+#include "sleep_api.h"
+#include "mbed_assert.h"
+#include "nu_modutil.h"
+#include "nu_miscutil.h"
+#include "mbed_critical.h"
+
+// us_ticker tick = us = timestamp
+#define US_PER_TICK             1
+#define US_PER_SEC              (1000 * 1000)
+
+#define TMR0HIRES_CLK_PER_SEC           (1000 * 1000)
+#define TMR1HIRES_CLK_PER_SEC           (1000 * 1000)
+
+#define US_PER_TMR0HIRES_CLK            (US_PER_SEC / TMR0HIRES_CLK_PER_SEC)
+#define US_PER_TMR1HIRES_CLK            (US_PER_SEC / TMR1HIRES_CLK_PER_SEC)
+
+#define US_PER_TMR0HIRES_INT            (1000 * 1000 * 10)
+#define TMR0HIRES_CLK_PER_TMR0HIRES_INT ((uint32_t) ((uint64_t) US_PER_TMR0HIRES_INT * TMR0HIRES_CLK_PER_SEC / US_PER_SEC))
+
+
+static void tmr0_vec(void);
+static void tmr1_vec(void);
+static void us_ticker_arm_cd(void);
+
+static int us_ticker_inited = 0;
+static volatile uint32_t counter_major = 0;
+static volatile uint32_t cd_major_minor_us = 0;
+static volatile uint32_t cd_minor_us = 0;
+
+// NOTE: PCLK is set up in mbed_sdk_init(), invocation of which must be before C++ global object constructor. See init_api.c for details.
+// NOTE: Choose clock source of timer:
+//       1. HIRC: Be the most accurate but might cause unknown HardFault.
+//       2. HXT: Less accurate and cannot pass mbed-drivers test.
+//       3. PCLK(HXT): Less accurate but can pass mbed-drivers test.
+// NOTE: TIMER_0 for normal counter, TIMER_1 for countdown.
+static const struct nu_modinit_s timer0hires_modinit = {TIMER_0, TMR0_MODULE, CLK_CLKSEL1_TMR0SEL_PCLK0, 0, TMR0_RST, TMR0_IRQn, (void *) tmr0_vec};
+static const struct nu_modinit_s timer1hires_modinit = {TIMER_1, TMR1_MODULE, CLK_CLKSEL1_TMR1SEL_PCLK0, 0, TMR1_RST, TMR1_IRQn, (void *) tmr1_vec};
+
+#define TMR_CMP_MIN         2
+#define TMR_CMP_MAX         0xFFFFFFu
+
+void us_ticker_init(void)
+{
+    if (us_ticker_inited) {
+        return;
+    }
+
+    counter_major = 0;
+    cd_major_minor_us = 0;
+    cd_minor_us = 0;
+    us_ticker_inited = 1;
+
+    // Reset IP
+    SYS_ResetModule(timer0hires_modinit.rsetidx);
+    SYS_ResetModule(timer1hires_modinit.rsetidx);
+
+    // Select IP clock source
+    CLK_SetModuleClock(timer0hires_modinit.clkidx, timer0hires_modinit.clksrc, timer0hires_modinit.clkdiv);
+    CLK_SetModuleClock(timer1hires_modinit.clkidx, timer1hires_modinit.clksrc, timer1hires_modinit.clkdiv);
+    // Enable IP clock
+    CLK_EnableModuleClock(timer0hires_modinit.clkidx);
+    CLK_EnableModuleClock(timer1hires_modinit.clkidx);
+
+    // Timer for normal counter
+    uint32_t clk_timer0 = TIMER_GetModuleClock((TIMER_T *) NU_MODBASE(timer0hires_modinit.modname));
+    uint32_t prescale_timer0 = clk_timer0 / TMR0HIRES_CLK_PER_SEC - 1;
+    MBED_ASSERT((prescale_timer0 != (uint32_t) -1) && prescale_timer0 <= 127);
+    MBED_ASSERT((clk_timer0 % TMR0HIRES_CLK_PER_SEC) == 0);
+    uint32_t cmp_timer0 = TMR0HIRES_CLK_PER_TMR0HIRES_INT;
+    MBED_ASSERT(cmp_timer0 >= TMR_CMP_MIN && cmp_timer0 <= TMR_CMP_MAX);
+    // NOTE: TIMER_CTL_CNTDATEN_Msk exists in NUC472, but not in M451/M480. In M451/M480, TIMER_CNT is updated continuously by default.
+    ((TIMER_T *) NU_MODBASE(timer0hires_modinit.modname))->CTL = TIMER_PERIODIC_MODE | prescale_timer0/* | TIMER_CTL_CNTDATEN_Msk*/;
+    ((TIMER_T *) NU_MODBASE(timer0hires_modinit.modname))->CMP = cmp_timer0;
+
+    NVIC_SetVector(timer0hires_modinit.irq_n, (uint32_t) timer0hires_modinit.var);
+    NVIC_SetVector(timer1hires_modinit.irq_n, (uint32_t) timer1hires_modinit.var);
+
+    NVIC_EnableIRQ(timer0hires_modinit.irq_n);
+    NVIC_EnableIRQ(timer1hires_modinit.irq_n);
+
+    TIMER_EnableInt((TIMER_T *) NU_MODBASE(timer0hires_modinit.modname));
+    TIMER_Start((TIMER_T *) NU_MODBASE(timer0hires_modinit.modname));
+}
+
+uint32_t us_ticker_read()
+{
+    if (! us_ticker_inited) {
+        us_ticker_init();
+    }
+
+    TIMER_T * timer0_base = (TIMER_T *) NU_MODBASE(timer0hires_modinit.modname);
+
+    do {
+        uint32_t major_minor_us;
+        uint32_t minor_us;
+
+        // 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_us = TIMER_GetCounter(timer0_base) * US_PER_TMR0HIRES_CLK;
+            uint32_t carry = (timer0_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_us > (US_PER_TMR0HIRES_INT / 2)) {
+                major_minor_us = (counter_major + 1) * US_PER_TMR0HIRES_INT;
+            } else {
+                major_minor_us = (counter_major + carry) * US_PER_TMR0HIRES_INT + minor_us;
+            }
+
+            core_util_critical_section_exit();
+        } while (minor_us == 0 || minor_us == US_PER_TMR0HIRES_INT);
+
+        return (major_minor_us / US_PER_TICK);
+    } while (0);
+}
+
+void us_ticker_disable_interrupt(void)
+{
+    TIMER_DisableInt((TIMER_T *) NU_MODBASE(timer1hires_modinit.modname));
+}
+
+void us_ticker_clear_interrupt(void)
+{
+    TIMER_ClearIntFlag((TIMER_T *) NU_MODBASE(timer1hires_modinit.modname));
+}
+
+void us_ticker_set_interrupt(timestamp_t timestamp)
+{
+    TIMER_Stop((TIMER_T *) NU_MODBASE(timer1hires_modinit.modname));
+
+    int delta = (int) (timestamp - us_ticker_read());
+    if (delta > 0) {
+        cd_major_minor_us = delta * US_PER_TICK;
+        us_ticker_arm_cd();
+    } else {
+        // NOTE: With us_ticker_fire_interrupt() introduced, upper layer would handle past event case.
+        //       This code fragment gets redundant, but it is still kept here for backward-compatible.
+        void us_ticker_fire_interrupt(void);
+        us_ticker_fire_interrupt();
+    }
+}
+
+void us_ticker_fire_interrupt(void)
+{
+    // NOTE: This event was in the past. Set the interrupt as pending, but don't process it here.
+    //       This prevents a recursive loop under heavy load which can lead to a stack overflow.
+    cd_major_minor_us = cd_minor_us = 0;
+    NVIC_SetPendingIRQ(timer1hires_modinit.irq_n);
+}
+
+static void tmr0_vec(void)
+{
+    TIMER_ClearIntFlag((TIMER_T *) NU_MODBASE(timer0hires_modinit.modname));
+    counter_major ++;
+}
+
+static void tmr1_vec(void)
+{
+    TIMER_ClearIntFlag((TIMER_T *) NU_MODBASE(timer1hires_modinit.modname));
+    cd_major_minor_us = (cd_major_minor_us > cd_minor_us) ? (cd_major_minor_us - cd_minor_us) : 0;
+    if (cd_major_minor_us == 0) {
+        // NOTE: us_ticker_set_interrupt() may get called in us_ticker_irq_handler();
+        us_ticker_irq_handler();
+    } else {
+        us_ticker_arm_cd();
+    }
+}
+
+static void us_ticker_arm_cd(void)
+{
+    TIMER_T * timer1_base = (TIMER_T *) NU_MODBASE(timer1hires_modinit.modname);
+
+    cd_minor_us = cd_major_minor_us;
+
+    // Reset 8-bit PSC counter, 24-bit up counter value and CNTEN bit
+    // NUC472/M451: See TIMER_CTL_RSTCNT_Msk
+    // M480
+    timer1_base->CNT = 0;
+    while (timer1_base->CNT & TIMER_CNT_RSTACT_Msk);
+    // One-shot mode, Clock = 1 MHz
+    uint32_t clk_timer1 = TIMER_GetModuleClock((TIMER_T *) NU_MODBASE(timer1hires_modinit.modname));
+    uint32_t prescale_timer1 = clk_timer1 / TMR1HIRES_CLK_PER_SEC - 1;
+    MBED_ASSERT((prescale_timer1 != (uint32_t) -1) && prescale_timer1 <= 127);
+    MBED_ASSERT((clk_timer1 % TMR1HIRES_CLK_PER_SEC) == 0);
+    // NOTE: TIMER_CTL_CNTDATEN_Msk exists in NUC472, but not in M451/M480. In M451/M480, TIMER_CNT is updated continuously by default.
+    timer1_base->CTL &= ~(TIMER_CTL_OPMODE_Msk | TIMER_CTL_PSC_Msk/* | TIMER_CTL_CNTDATEN_Msk*/);
+    timer1_base->CTL |= TIMER_ONESHOT_MODE | prescale_timer1/* | TIMER_CTL_CNTDATEN_Msk*/;
+
+    uint32_t cmp_timer1 = cd_minor_us / US_PER_TMR1HIRES_CLK;
+    cmp_timer1 = NU_CLAMP(cmp_timer1, TMR_CMP_MIN, TMR_CMP_MAX);
+    timer1_base->CMP = cmp_timer1;
+
+    TIMER_EnableInt(timer1_base);
+    TIMER_Start(timer1_base);
+}