[EV3] Implement the rest of the clock API

lib/pbio/drv/clock/clock_ev3.c

@@ -21,16 +21,16 @@
 #include <tiam1808/hw/soc_AM1808.h>
 #include <tiam1808/timer.h>
 
-/**
- * The compare value to set for the 16 least significant bits of the hardware timer
- *
- * This is the value which causes the interrupt to be triggered every millisecond.
- */
-#define TMR_PERIOD_LSB32              0x05CC
-/*
- * The compare value to set for the 16 most significant bits of the hardware timer
- */
-#define TMR_PERIOD_MSB32              0x0
+// The input to the Timer0 module is PLL0_AUXCLK. This will always run at 24 MHz on the EV3,
+// regardless of what the CPU speed is set to. We configure the timer to generate interrupts
+// every millisecond, and we configure the timer to reset to 0 when it reaches a count value
+// corresponding to one millisecond of time. Finer timing resolution can be obtained by
+// combining the software-managed millisecond counter with the timer value.
+//
+// The system tick uses the "12" half of the timer, and the PRU1 (TODO) uses the "34" half.
+static const uint32_t auxclk_freq_hz = SOC_ASYNC_2_FREQ;
+static const uint32_t timer_ms_period = (auxclk_freq_hz / 1000) - 1;
+static const uint32_t timer_us_division = auxclk_freq_hz / 1000000;
 
 /**
  * The current tick in milliseconds
@@ -41,37 +41,14 @@ volatile uint32_t systick_ms = 0;
  * The systick interrupt service routine (ISR) which will be called every millisecond.
  */
 void systick_isr_C(void) {
-    /* Disable the timer interrupt */
-    TimerIntDisable(SOC_TMR_0_REGS, TMR_INT_TMR34_NON_CAPT_MODE);
-
     /* Clear the interrupt status in AINTC and in timer */
-    IntSystemStatusClear(SYS_INT_TINT34_0);
-    TimerIntStatusClear(SOC_TMR_0_REGS, TMR_INT_TMR34_NON_CAPT_MODE);
+    IntSystemStatusClear(SYS_INT_TINT12_0);
+    TimerIntStatusClear(SOC_TMR_0_REGS, TMR_INTSTAT12_TIMER_NON_CAPT);
 
     ++systick_ms;
 
     etimer_request_poll();
     pbio_os_request_poll();
-
-    /* Enable the timer interrupt */
-    TimerIntEnable(SOC_TMR_0_REGS, TMR_INT_TMR34_NON_CAPT_MODE);
-}
-
-/**
- * Disable the timer and therefore the systick
- *
- */
-void systick_suspend(void) {
-    /* Disable the timer interrupt */
-    TimerDisable(SOC_TMR_0_REGS, TMR_TIMER34);
-}
-
-/**
- * Enable the timer and therefore the systick
- */
-void systick_resume(void) {
-    /* Enable the timer interrupt */
-    TimerEnable(SOC_TMR_0_REGS, TMR_TIMER34, TMR_ENABLE_CONTRELOAD);
 }
 
 /**
@@ -86,37 +63,38 @@ void pbdrv_clock_init(void) {
 
     /* Set up the timer */
     TimerConfigure(SOC_TMR_0_REGS, TMR_CFG_32BIT_UNCH_CLK_BOTH_INT);
-    TimerPeriodSet(SOC_TMR_0_REGS, TMR_TIMER34, TMR_PERIOD_LSB32);
-    TimerReloadSet(SOC_TMR_0_REGS, TMR_TIMER34, TMR_PERIOD_LSB32);
+    TimerPeriodSet(SOC_TMR_0_REGS, TMR_TIMER12, timer_ms_period);
 
     /* Register the Timer ISR */
-    IntRegister(SYS_INT_TINT34_0, systick_isr_C);
+    IntRegister(SYS_INT_TINT12_0, systick_isr_C);
 
     /* Set the channel number for Timer interrupt, it will map to IRQ */
-    IntChannelSet(SYS_INT_TINT34_0, 3);
+    IntChannelSet(SYS_INT_TINT12_0, 3);
 
     /* Enable timer interrupts in AINTC */
-    IntSystemEnable(SYS_INT_TINT34_0);
+    IntSystemEnable(SYS_INT_TINT12_0);
 
     /* Enable the timer interrupt */
-    TimerIntEnable(SOC_TMR_0_REGS, TMR_INT_TMR34_NON_CAPT_MODE);
+    TimerIntEnable(SOC_TMR_0_REGS, TMR_INT_TMR12_NON_CAPT_MODE);
 
     /* Start the timer */
-    TimerEnable(SOC_TMR_0_REGS, TMR_TIMER34, TMR_ENABLE_CONTRELOAD);
+    TimerEnable(SOC_TMR_0_REGS, TMR_TIMER12, TMR_ENABLE_CONT);
 }
 
 uint32_t pbdrv_clock_get_us(void) {
-    // TODO: TIAM1808 implementation.
-    return 0;
+    uint32_t tim_val = TimerCounterGet(SOC_TMR_0_REGS, TMR_TIMER12);
+    uint32_t t_us = tim_val / timer_us_division;
+    return pbdrv_clock_get_ms() * 1000 + t_us;
 }
 
 uint32_t pbdrv_clock_get_ms(void) {
     return systick_ms;
 }
 
 uint32_t pbdrv_clock_get_100us(void) {
-    // REVISIT: Use actual time since this isn't providing better resolution.
-    return pbdrv_clock_get_ms() * 10;
+    uint32_t tim_val = TimerCounterGet(SOC_TMR_0_REGS, TMR_TIMER12);
+    uint32_t t_100_us = tim_val / timer_us_division / 100;
+    return pbdrv_clock_get_ms() * 10 + t_100_us;
 }
 
 #endif // PBDRV_CONFIG_CLOCK_TIAM1808