Diff: targets/TARGET_NUVOTON/TARGET_M480/lp_ticker.c

Revision:

182:a56a73fd2a6f

Parent:

179:b0033dcd6934

Child:

184:08ed48f1de7f

--- a/targets/TARGET_NUVOTON/TARGET_M480/lp_ticker.c	Fri Feb 16 16:09:33 2018 +0000
+++ b/targets/TARGET_NUVOTON/TARGET_M480/lp_ticker.c	Tue Mar 20 16:56:18 2018 +0000
@@ -19,200 +19,141 @@
 #if DEVICE_LOWPOWERTIMER
 
 #include "sleep_api.h"
+#include "mbed_wait_api.h"
+#include "mbed_assert.h"
 #include "nu_modutil.h"
 #include "nu_miscutil.h"
-#include "mbed_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);
+/* Micro seconds per second */
+#define NU_US_PER_SEC               1000000
+/* Timer clock per lp_ticker tick */
+#define NU_TMRCLK_PER_TICK          1
+/* Timer clock per second */
+#define NU_TMRCLK_PER_SEC           (__LXT)
+/* Timer max counter bit size */
+#define NU_TMR_MAXCNT_BITSIZE       24
+/* Timer max counter */
+#define NU_TMR_MAXCNT               ((1 << NU_TMR_MAXCNT_BITSIZE) - 1)
 
-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;
+static void tmr1_vec(void);
 
-// 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};
+/* NOTE: To wake the system from power down mode, timer clock source must be ether LXT or LIRC. */
+static const struct nu_modinit_s timer1_modinit = {TIMER_1, TMR1_MODULE, CLK_CLKSEL1_TMR1SEL_LXT, 0, TMR1_RST, TMR1_IRQn, (void *) tmr1_vec};
+
+#define TIMER_MODINIT      timer1_modinit
+
+static int ticker_inited = 0;
 
 #define TMR_CMP_MIN         2
 #define TMR_CMP_MAX         0xFFFFFFu
 
 void lp_ticker_init(void)
 {
-    if (lp_ticker_inited) {
+    if (ticker_inited) {
         return;
     }
-    lp_ticker_inited = 1;
-
-    counter_major = 0;
-    cd_major_minor_clks = 0;
-    cd_minor_clks = 0;
-    wakeup_tick = (uint32_t) -1;
+    ticker_inited = 1;
 
     // Reset module
-    SYS_ResetModule(timer2_modinit.rsetidx);
-    SYS_ResetModule(timer3_modinit.rsetidx);
+    SYS_ResetModule(TIMER_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);
+    CLK_SetModuleClock(TIMER_MODINIT.clkidx, TIMER_MODINIT.clksrc, TIMER_MODINIT.clkdiv);
+
     // Enable IP clock
-    CLK_EnableModuleClock(timer2_modinit.clkidx);
-    CLK_EnableModuleClock(timer3_modinit.clkidx);
+    CLK_EnableModuleClock(TIMER_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);
+    uint32_t clk_timer = TIMER_GetModuleClock((TIMER_T *) NU_MODBASE(TIMER_MODINIT.modname));
+    uint32_t prescale_timer = clk_timer / NU_TMRCLK_PER_SEC - 1;
+    MBED_ASSERT((prescale_timer != (uint32_t) -1) && prescale_timer <= 127);
+    MBED_ASSERT((clk_timer % NU_TMRCLK_PER_SEC) == 0);
+    uint32_t cmp_timer = TMR_CMP_MAX;
+    MBED_ASSERT(cmp_timer >= TMR_CMP_MIN && cmp_timer <= TMR_CMP_MAX);
     // Continuous mode
     // 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(timer2_modinit.modname))->CTL = TIMER_PERIODIC_MODE | prescale_timer2/* | TIMER_CTL_CNTDATEN_Msk*/;
-    ((TIMER_T *) NU_MODBASE(timer2_modinit.modname))->CMP = cmp_timer2;
+    ((TIMER_T *) NU_MODBASE(TIMER_MODINIT.modname))->CTL = TIMER_CONTINUOUS_MODE | prescale_timer/* | TIMER_CTL_CNTDATEN_Msk*/;
+    ((TIMER_T *) NU_MODBASE(TIMER_MODINIT.modname))->CMP = cmp_timer;
 
     // 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_SetVector(TIMER_MODINIT.irq_n, (uint32_t) TIMER_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));
+    NVIC_EnableIRQ(TIMER_MODINIT.irq_n);
 
-    // NOTE: TIMER_Start() first and then lp_ticker_set_interrupt(); otherwise, we may get stuck in lp_ticker_read() because
-    //       timer is not running.
-
-    // Start timer
-    TIMER_Start((TIMER_T *) NU_MODBASE(timer2_modinit.modname));
-
-    // Schedule wakeup to match semantics of lp_ticker_get_compare_match()
-    lp_ticker_set_interrupt(wakeup_tick);
+    TIMER_EnableInt((TIMER_T *) NU_MODBASE(TIMER_MODINIT.modname));
+    TIMER_EnableWakeup((TIMER_T *) NU_MODBASE(TIMER_MODINIT.modname));
+    /* 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_TMRCLK_PER_SEC) * 3);
+    TIMER_Start((TIMER_T *) NU_MODBASE(TIMER_MODINIT.modname));
 }
 
 timestamp_t lp_ticker_read()
 {
-    if (! lp_ticker_inited) {
+    if (! 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();
+    TIMER_T * timer_base = (TIMER_T *) NU_MODBASE(TIMER_MODINIT.modname);
 
-            // 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. Handle 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 / TMR2_CLK_PER_SEC / US_PER_TICK);
-    } while (0);
+    return  (TIMER_GetCounter(timer_base) / NU_TMRCLK_PER_TICK);
 }
 
 void lp_ticker_set_interrupt(timestamp_t timestamp)
 {
-    uint32_t delta = timestamp - lp_ticker_read();
-    wakeup_tick = timestamp;
+    /* In continuous mode, counter will be reset to zero with the following sequence: 
+     * 1. Stop counting
+     * 2. Configure new CMP value
+     * 3. Restart counting
+     *
+     * This behavior is not what we want. To fix it, we could configure new CMP value
+     * without stopping counting first.
+     */
+    TIMER_T * timer_base = (TIMER_T *) NU_MODBASE(TIMER_MODINIT.modname);
 
-    TIMER_Stop((TIMER_T *) NU_MODBASE(timer3_modinit.modname));
+    /* NOTE: Because H/W timer requests min compare value, our implementation would have alarm delay of 
+     *       (TMR_CMP_MIN - interval_clk) clocks when interval_clk is between [1, TMR_CMP_MIN). */
+    uint32_t cmp_timer = timestamp * NU_TMRCLK_PER_TICK;
+    cmp_timer = NU_CLAMP(cmp_timer, TMR_CMP_MIN, TMR_CMP_MAX);
+    timer_base->CMP = cmp_timer;
 
-    cd_major_minor_clks = (uint64_t) delta * US_PER_TICK * TMR3_CLK_PER_SEC / US_PER_SEC;
-    lp_ticker_arm_cd();
+    /* 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_TMRCLK_PER_SEC) * 3);
+    TIMER_Start(timer_base);
+}
+
+void lp_ticker_disable_interrupt(void)
+{
+    TIMER_DisableInt((TIMER_T *) NU_MODBASE(TIMER_MODINIT.modname));
+}
+
+void lp_ticker_clear_interrupt(void)
+{
+    TIMER_ClearIntFlag((TIMER_T *) NU_MODBASE(TIMER_MODINIT.modname));
 }
 
 void lp_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_clks = cd_minor_clks = 0;
-    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 ++;
+    NVIC_SetPendingIRQ(TIMER_MODINIT.irq_n);
 }
 
-static void tmr3_vec(void)
+const ticker_info_t* lp_ticker_get_info()
 {
-    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 const ticker_info_t info = {
+        NU_TMRCLK_PER_SEC / NU_TMRCLK_PER_TICK,
+        NU_TMR_MAXCNT_BITSIZE
+    };
+    return &info;
 }
 
-static void lp_ticker_arm_cd(void)
+static void tmr1_vec(void)
 {
-    TIMER_T * timer3_base = (TIMER_T *) NU_MODBASE(timer3_modinit.modname);
+    TIMER_ClearIntFlag((TIMER_T *) NU_MODBASE(TIMER_MODINIT.modname));
+    TIMER_ClearWakeupFlag((TIMER_T *) NU_MODBASE(TIMER_MODINIT.modname));
+    
+    // NOTE: lp_ticker_set_interrupt() may get called in lp_ticker_irq_handler();
+    lp_ticker_irq_handler();
+}
 
-    // Reset 8-bit PSC counter, 24-bit up counter value and CNTEN bit
-    // NUC472/M451: See TIMER_CTL_RSTCNT_Msk
-    // M480
-    timer3_base->CNT = 0;
-    while (timer3_base->CNT & TIMER_CNT_RSTACT_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/M480. In M451/M480, 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