Diff: targets/TARGET_NUVOTON/TARGET_NUC472/us_ticker.c

Revision:

182:a56a73fd2a6f

Parent:

174:b96e65c34a4d

Child:

184:08ed48f1de7f

--- a/targets/TARGET_NUVOTON/TARGET_NUC472/us_ticker.c	Fri Feb 16 16:09:33 2018 +0000
+++ b/targets/TARGET_NUVOTON/TARGET_NUC472/us_ticker.c	Tue Mar 20 16:56:18 2018 +0000
@@ -13,192 +13,129 @@
  * 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))
-
+/* Micro seconds per second */
+#define NU_US_PER_SEC               1000000
+/* Timer clock per us_ticker tick */
+#define NU_TMRCLK_PER_TICK          1
+/* Timer clock per second */
+#define NU_TMRCLK_PER_SEC           (1000 * 1000)
+/* 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 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;
+static const struct nu_modinit_s timer0_modinit = {TIMER_0, TMR0_MODULE, CLK_CLKSEL1_TMR0SEL_PCLK, 0, TMR0_RST, TMR0_IRQn, (void *) tmr0_vec};
 
-// 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_PCLK, 0, TMR0_RST, TMR0_IRQn, (void *) tmr0_vec};
-static const struct nu_modinit_s timer1hires_modinit = {TIMER_1, TMR1_MODULE, CLK_CLKSEL1_TMR1SEL_PCLK, 0, TMR1_RST, TMR1_IRQn, (void *) tmr1_vec};
+#define TIMER_MODINIT      timer0_modinit
+
+static int ticker_inited = 0;
 
 #define TMR_CMP_MIN         2
 #define TMR_CMP_MAX         0xFFFFFFu
 
 void us_ticker_init(void)
 {
-    if (us_ticker_inited) {
+    if (ticker_inited) {
         return;
     }
-    
-    counter_major = 0;
-    cd_major_minor_us = 0;
-    cd_minor_us = 0;
-    us_ticker_inited = 1;
-    
+    ticker_inited = 1;
+
     // Reset IP
-    SYS_ResetModule(timer0hires_modinit.rsetidx);
-    SYS_ResetModule(timer1hires_modinit.rsetidx);
-    
+    SYS_ResetModule(TIMER_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);
+    CLK_SetModuleClock(TIMER_MODINIT.clkidx, TIMER_MODINIT.clksrc, TIMER_MODINIT.clkdiv);
+
     // Enable IP clock
-    CLK_EnableModuleClock(timer0hires_modinit.clkidx);
-    CLK_EnableModuleClock(timer1hires_modinit.clkidx);
+    CLK_EnableModuleClock(TIMER_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);
-    ((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 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);
+    ((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;
+
+    NVIC_SetVector(TIMER_MODINIT.irq_n, (uint32_t) TIMER_MODINIT.var);
+
+    NVIC_EnableIRQ(TIMER_MODINIT.irq_n);
+
+    TIMER_EnableInt((TIMER_T *) NU_MODBASE(TIMER_MODINIT.modname));
+    TIMER_Start((TIMER_T *) NU_MODBASE(TIMER_MODINIT.modname));
 }
 
 uint32_t us_ticker_read()
 {
-    if (! us_ticker_inited) {
+    if (! 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);
-}
+    TIMER_T * timer_base = (TIMER_T *) NU_MODBASE(TIMER_MODINIT.modname);
 
-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));
+    return  (TIMER_GetCounter(timer_base) / NU_TMRCLK_PER_TICK);
 }
 
 void us_ticker_set_interrupt(timestamp_t timestamp)
 {
-    TIMER_Stop((TIMER_T *) NU_MODBASE(timer1hires_modinit.modname));
-    
-    uint32_t delta = timestamp - us_ticker_read();
-    cd_major_minor_us = delta * US_PER_TICK;
-    us_ticker_arm_cd();
+    /* 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);
+
+    /* 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;
+}
+
+void us_ticker_disable_interrupt(void)
+{
+    TIMER_DisableInt((TIMER_T *) NU_MODBASE(TIMER_MODINIT.modname));
+}
+
+void us_ticker_clear_interrupt(void)
+{
+    TIMER_ClearIntFlag((TIMER_T *) NU_MODBASE(TIMER_MODINIT.modname));
 }
 
 void us_ticker_fire_interrupt(void)
 {
-    cd_major_minor_us = cd_minor_us = 0;
-    NVIC_SetPendingIRQ(timer1hires_modinit.irq_n);
+    // 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.
+    NVIC_SetPendingIRQ(TIMER_MODINIT.irq_n);
+}
+
+const ticker_info_t* us_ticker_get_info()
+{
+    static const ticker_info_t info = {
+        NU_TMRCLK_PER_SEC / NU_TMRCLK_PER_TICK,
+        NU_TMR_MAXCNT_BITSIZE
+    };
+    return &info;
 }
 
 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();
-    }
+    TIMER_ClearIntFlag((TIMER_T *) NU_MODBASE(TIMER_MODINIT.modname));
+    
+    // NOTE: us_ticker_set_interrupt() may get called in us_ticker_irq_handler();
+    us_ticker_irq_handler();
 }
-
-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
-    timer1_base->CTL |= TIMER_CTL_RSTCNT_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);
-    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);
-}