diff options
| author | Joel Sherrill <joel.sherrill@OARcorp.com> | 2011-03-04 16:03:46 +0000 |
|---|---|---|
| committer | Joel Sherrill <joel.sherrill@OARcorp.com> | 2011-03-04 16:03:46 +0000 |
| commit | 3f60fb4f3aac86eaa327438004e59ee348a3d84d (patch) | |
| tree | f9905848f62fe7ab794e7a574b647d946327c588 /c/src/lib/libbsp/m68k/uC5282/clock/clock.c | |
| parent | 2011-03-04 Joel Sherrill <joel.sherrilL@OARcorp.com> (diff) | |
| download | rtems-3f60fb4f3aac86eaa327438004e59ee348a3d84d.tar.bz2 | |
2011-03-04 Till Straumann <strauman@slac.stanford.edu>
PR 1738/bsps
* clock/clock.c, include/bsp.h, network/network.c: system clock driver
programs the PIT w/o assuming the CPU clock frequency being a power
of two.
Diffstat (limited to 'c/src/lib/libbsp/m68k/uC5282/clock/clock.c')
| -rw-r--r-- | c/src/lib/libbsp/m68k/uC5282/clock/clock.c | 55 |
1 files changed, 33 insertions, 22 deletions
diff --git a/c/src/lib/libbsp/m68k/uC5282/clock/clock.c b/c/src/lib/libbsp/m68k/uC5282/clock/clock.c index 2bcc1787dd..b8037d5372 100644 --- a/c/src/lib/libbsp/m68k/uC5282/clock/clock.c +++ b/c/src/lib/libbsp/m68k/uC5282/clock/clock.c @@ -26,19 +26,19 @@ * CPU load counters * Place in static RAM so updates don't hit the SDRAM */ -extern int __SRAMBASE[]; -#define IDLE_COUNTER __SRAMBASE[0] -#define FILTERED_IDLE __SRAMBASE[1] -#define MAX_IDLE_COUNT __SRAMBASE[2] -#define USEC_PER_TICK __SRAMBASE[3] +#define IDLE_COUNTER __SRAMBASE.idle_counter +#define FILTERED_IDLE __SRAMBASE.filtered_idle +#define MAX_IDLE_COUNT __SRAMBASE.max_idle_count +#define PITC_PER_TICK __SRAMBASE.pitc_per_tick +#define NSEC_PER_PITC __SRAMBASE.nsec_per_pitc #define FILTER_SHIFT 6 uint32_t bsp_clock_nanoseconds_since_last_tick(void) { int i = MCF5282_PIT3_PCNTR; if (MCF5282_PIT3_PCSR & MCF5282_PIT_PCSR_PIF) - i = MCF5282_PIT3_PCNTR - USEC_PER_TICK; - return (USEC_PER_TICK - i) * 1000; + i = MCF5282_PIT3_PCNTR - PITC_PER_TICK; + return (PITC_PER_TICK - i) * NSEC_PER_PITC; } #define Clock_driver_nanoseconds_since_last_tick bsp_clock_nanoseconds_since_last_tick @@ -48,7 +48,7 @@ uint32_t bsp_clock_nanoseconds_since_last_tick(void) */ #define Clock_driver_support_at_tick() \ do { \ - int idle = IDLE_COUNTER; \ + unsigned idle = IDLE_COUNTER; \ IDLE_COUNTER = 0; \ if (idle > MAX_IDLE_COUNT) \ MAX_IDLE_COUNT = idle; \ @@ -75,20 +75,31 @@ uint32_t bsp_clock_nanoseconds_since_last_tick(void) /* * Set up the clock hardware * - * Prescale so that it counts in microseconds - * System clock frequency better be 2**n (1<=n<=16) MHz! + * f_pit = f_clk / 2^(preScaleCode+1) / N = 1/(us_per_tick/us_per_s) + * + * N = f_clk / 2^(preScaleCode+1) * us_per_tick / us_per_s + * + * ns_per_pit_clk = ns_per_s / (f_clk / 2^(preScaleCode+1)) + * = ns_per_s * 2^(preScaleCode+1) / f_clk; */ #define Clock_driver_support_initialize_hardware() \ do { \ + unsigned long long N; \ int level; \ - int preScaleCode = -2; \ - int preScaleDivisor = bsp_get_CPU_clock_speed() / 1000000; \ - while (preScaleDivisor) { \ - preScaleDivisor >>= 1; \ - preScaleCode++; \ - } \ - IDLE_COUNTER = 0; \ - FILTERED_IDLE = 0; \ + int preScaleCode = 0; \ + N = bsp_get_CPU_clock_speed(); \ + N *= rtems_configuration_get_microseconds_per_tick(); \ + N /= 2*1000000; /* min_prescale * us_per_s */ \ + while ( N > 0x10000 ) { \ + preScaleCode++; \ + N >>= 1; \ + } \ + PITC_PER_TICK = N; \ + N = 2000000000ULL << preScaleCode; \ + N /= bsp_get_CPU_clock_speed(); \ + NSEC_PER_PITC = N; \ + IDLE_COUNTER = 0; \ + FILTERED_IDLE = 0; \ MAX_IDLE_COUNT = 0; \ bsp_allocate_interrupt(PIT3_IRQ_LEVEL, PIT3_IRQ_PRIORITY); \ MCF5282_INTC0_ICR58 = MCF5282_INTC_ICR_IL(PIT3_IRQ_LEVEL) | \ @@ -101,8 +112,7 @@ uint32_t bsp_clock_nanoseconds_since_last_tick(void) MCF5282_PIT_PCSR_OVW | \ MCF5282_PIT_PCSR_PIE | \ MCF5282_PIT_PCSR_RLD; \ - USEC_PER_TICK = rtems_configuration_get_microseconds_per_tick(); \ - MCF5282_PIT3_PMR = USEC_PER_TICK - 1; \ + MCF5282_PIT3_PMR = PITC_PER_TICK - 1; \ MCF5282_PIT3_PCSR = MCF5282_PIT_PCSR_PRE(preScaleCode) | \ MCF5282_PIT_PCSR_PIE | \ MCF5282_PIT_PCSR_RLD | \ @@ -114,8 +124,9 @@ uint32_t bsp_clock_nanoseconds_since_last_tick(void) */ Thread bsp_idle_thread(uint32_t ignored) { - for(;;) - __asm__ volatile ("addq.l #1,__SRAMBASE"); /* Atomic increment */ + /* Atomic increment */ + for(;;) + __asm__ volatile ("addq.l #1,%0"::"m"(IDLE_COUNTER)); } int rtems_bsp_cpu_load_percentage(void) |