mimxrt: Fix cycle counter for time.ticks_cpu() and machine.bitstream().

robert-hh · dpgeorge · commit 99221cd11812 · 2021-10-25T15:50:44.000+11:00
Prior to this commit mp_hal_ticks_cpu() was not started properly.  It only
started when the code was executed with a debugger attached, except for the
Teensy (i.MXRT1062) boards.  As an additional fix, the CYYCNT timer is now
started at boot time.

Also rename mp_hal_ticks_cpu_init() to mp_hal_ticks_cpu_enable().
diff --git a/ports/mimxrt/machine_bitstream.c b/ports/mimxrt/machine_bitstream.c
@@ -48,7 +48,7 @@ void machine_bitstream_high_low(mp_hal_pin_obj_t pin, uint32_t *timing_ns, const
         }
     }
     // Enable the CPU cycle counter, which is not always enabled.
-    mp_hal_ticks_cpu_init();
+    mp_hal_ticks_cpu_enable();
 
     uint32_t irq_state = mp_hal_quiet_timing_enter();
 
diff --git a/ports/mimxrt/mphalport.h b/ports/mimxrt/mphalport.h
@@ -75,7 +75,10 @@ static inline void mp_hal_delay_us(mp_uint_t us) {
 
 #define mp_hal_delay_us_fast(us) mp_hal_delay_us(us)
 
-static inline void mp_hal_ticks_cpu_init(void) {
+static inline void mp_hal_ticks_cpu_enable(void) {
+    CoreDebug->DEMCR |= CoreDebug_DEMCR_TRCENA_Msk;
+    DWT->LAR = 0xc5acce55;
+    DWT->CYCCNT = 0;
     DWT->CTRL |= DWT_CTRL_CYCCNTENA_Msk;
 }
 
diff --git a/ports/mimxrt/ticks.c b/ports/mimxrt/ticks.c
@@ -56,6 +56,7 @@ void ticks_init(void) {
     NVIC_EnableIRQ(GPTx_IRQn);
 
     GPT_StartTimer(GPTx);
+    mp_hal_ticks_cpu_enable();
 }
 
 void GPTx_IRQHandler(void) {

Original file line number	Diff line number	Diff line change
`@@ -48,7 +48,7 @@ void machine_bitstream_high_low(mp_hal_pin_obj_t pin, uint32_t *timing_ns, const`
`48`	`48`	`}`
`49`	`49`	`}`
`50`	`50`	`// Enable the CPU cycle counter, which is not always enabled.`
`51`		`- mp_hal_ticks_cpu_init();`
	`51`	`+ mp_hal_ticks_cpu_enable();`
`52`	`52`
`53`	`53`	`uint32_t irq_state = mp_hal_quiet_timing_enter();`
`54`	`54`
Original file line number	Diff line number	Diff line change
`@@ -75,7 +75,10 @@ static inline void mp_hal_delay_us(mp_uint_t us) {`
`75`	`75`
`76`	`76`	`#define mp_hal_delay_us_fast(us) mp_hal_delay_us(us)`
`77`	`77`
`78`		`-static inline void mp_hal_ticks_cpu_init(void) {`
	`78`	`+static inline void mp_hal_ticks_cpu_enable(void) {`
	`79`	`+ CoreDebug->DEMCR \|= CoreDebug_DEMCR_TRCENA_Msk;`
	`80`	`+ DWT->LAR = 0xc5acce55;`
	`81`	`+ DWT->CYCCNT = 0;`
`79`	`82`	`DWT->CTRL \|= DWT_CTRL_CYCCNTENA_Msk;`
`80`	`83`	`}`
`81`	`84`
Original file line number	Diff line number	Diff line change
`@@ -56,6 +56,7 @@ void ticks_init(void) {`
`56`	`56`	`NVIC_EnableIRQ(GPTx_IRQn);`
`57`	`57`
`58`	`58`	`GPT_StartTimer(GPTx);`
	`59`	`+ mp_hal_ticks_cpu_enable();`
`59`	`60`	`}`
`60`	`61`
`61`	`62`	`void GPTx_IRQHandler(void) {`