DECLARE_GLOBAL_DATA_PTR;
-#define timestamp (gd->tbl)
-#define lastdec (gd->lastinc)
+/* Enable this to verify that the code can correctly
+ * handle the timer rollover
+ */
+/* #define DEBUG_TIMER_WRAP */
+
+#ifdef DEBUG_TIMER_WRAP
+/*
+ * Let the timer wrap 15 seconds after start to catch misbehaving
+ * timer related code early
+ */
+#define TIMER_START (-time_to_tick(15 * CONFIG_SYS_HZ))
+#else
+#define TIMER_START 0UL
+#endif
/*
* This driver uses 1kHz clock source.
return time * (MX28_INCREMENTER_HZ / CONFIG_SYS_HZ);
}
-/* Calculate how many ticks happen in "us" microseconds */
-static inline unsigned long us_to_tick(unsigned long us)
-{
- return (us * MX28_INCREMENTER_HZ) / 1000000;
-}
-
int timer_init(void)
{
struct mx28_timrot_regs *timrot_regs =
TIMROT_TIMCTRLn_SELECT_1KHZ_XTAL,
&timrot_regs->hw_timrot_timctrl0);
- /* Set fixed_count to maximal value */
+#ifndef DEBUG_TIMER_WRAP
+ /* Set fixed_count to maximum value */
writel(TIMER_LOAD_VAL, &timrot_regs->hw_timrot_fixed_count0);
-
+#else
+ /* Set fixed_count so that the counter will wrap after 20 seconds */
+ writel(20 * MX28_INCREMENTER_HZ,
+ &timrot_regs->hw_timrot_fixed_count0);
+ gd->lastinc = TIMER_LOAD_VAL - 20 * MX28_INCREMENTER_HZ;
+#endif
+#ifdef DEBUG_TIMER_WRAP
+ /* Make the usec counter roll over 30 seconds after startup */
+ writel(-30000000, MX28_HW_DIGCTL_MICROSECONDS);
+#endif
+ writel(TIMROT_TIMCTRLn_UPDATE,
+ &timrot_regs->hw_timrot_timctrl0_clr);
+#ifdef DEBUG_TIMER_WRAP
+ /* Set fixed_count to maximal value for subsequent loads */
+ writel(TIMER_LOAD_VAL, &timrot_regs->hw_timrot_fixed_count0);
+#endif
+ gd->timer_rate_hz = MX28_INCREMENTER_HZ;
+ gd->tbl = TIMER_START;
+ gd->tbu = 0;
return 0;
}
+/* We use the HW_DIGCTL_MICROSECONDS register for sub-millisecond timer. */
+#define MX28_HW_DIGCTL_MICROSECONDS 0x8001c0c0
+
+void __udelay(unsigned long usec)
+{
+ uint32_t start = readl(MX28_HW_DIGCTL_MICROSECONDS);
+
+ while (readl(MX28_HW_DIGCTL_MICROSECONDS) - start <= usec)
+ /* use '<=' to guarantee a delay of _at least_
+ * the given number of microseconds.
+ * No need for fancy rollover checks
+ * Two's complement arithmetic applied correctly
+ * does everything that's needed automagically!
+ */
+ ;
+}
+
+/* Note: This function works correctly for TIMER_LOAD_VAL == 0xffffffff!
+ * The rollover is handled automagically due to the properties of
+ * two's complement arithmetic.
+ * For any other value of TIMER_LOAD_VAL the calculations would have
+ * to be done modulus(TIMER_LOAD_VAL + 1).
+ */
unsigned long long get_ticks(void)
{
struct mx28_timrot_regs *timrot_regs =
(struct mx28_timrot_regs *)MXS_TIMROT_BASE;
-
- /* Current tick value */
- uint32_t now = readl(&timrot_regs->hw_timrot_running_count0);
-
- if (lastdec >= now) {
- /*
- * normal mode (non roll)
- * move stamp forward with absolut diff ticks
- */
- timestamp += (lastdec - now);
- } else {
- /* we have rollover of decrementer */
- timestamp += (TIMER_LOAD_VAL - now) + lastdec;
-
- }
- lastdec = now;
-
- return timestamp;
+ /* The timer is counting down, so subtract the register value from
+ * the counter period length to get an incrementing timestamp
+ */
+ unsigned long now = -readl(&timrot_regs->hw_timrot_running_count0);
+ ulong inc = now - gd->lastinc;
+
+ gd->tbl += inc;
+ gd->lastinc = now;
+ /* Since the get_timer() function only uses a 32bit value
+ * it doesn't make sense to return a real 64 bit value here.
+ */
+ return gd->tbl;
}
ulong get_timer_masked(void)
ulong get_timer(ulong base)
{
- return get_timer_masked() - base;
-}
-
-/* We use the HW_DIGCTL_MICROSECONDS register for sub-millisecond timer. */
-#define MX28_HW_DIGCTL_MICROSECONDS 0x8001c0c0
-
-void __udelay(unsigned long usec)
-{
- uint32_t old, new, incr;
- uint32_t counter = 0;
-
- old = readl(MX28_HW_DIGCTL_MICROSECONDS);
-
- while (counter < usec) {
- new = readl(MX28_HW_DIGCTL_MICROSECONDS);
-
- /* Check if the timer wrapped. */
- if (new < old) {
- incr = 0xffffffff - old;
- incr += new;
- } else {
- incr = new - old;
- }
-
- /*
- * Check if we are close to the maximum time and the counter
- * would wrap if incremented. If that's the case, break out
- * from the loop as the requested delay time passed.
- */
- if (counter + incr < counter)
- break;
-
- counter += incr;
- old = new;
- }
+ /* NOTE: time_to_tick(base) is required to correctly handle rollover! */
+ return tick_to_time(get_ticks() - time_to_tick(base));
}
+/*
+ * This function is derived from PowerPC code (timebase clock frequency).
+ * On ARM it returns the number of timer ticks per second.
+ */
ulong get_tbclk(void)
{
- return MX28_INCREMENTER_HZ;
+ return gd->timer_rate_hz;
}
projects / karo-tx-uboot.git / blobdiff