minix/kernel/arch/earm/omap_timer.c
Ben Gras 8ea66915f2 kernel: scheduling fix for ARM
. make read_tsc_64 use the free-running clock, significantly
	  improving scheduling behaviour

Change-Id: Idf6a12f6e26be7fe3b3664c278cae846d8b2a442
2013-02-03 22:49:05 +01:00

131 lines
3.3 KiB
C

#include "kernel/kernel.h"
#include "kernel/clock.h"
#include <sys/types.h>
#include <machine/cpu.h>
#include <io.h>
#include "arch_proto.h"
#include "omap_timer.h"
#include "omap_intr.h"
static irq_hook_t omap3_timer_hook; /* interrupt handler hook */
static u64_t high_frc;
vir_bytes omap3_gptimer10_base;
int omap3_register_timer_handler(const irq_handler_t handler)
{
/* Initialize the CLOCK's interrupt hook. */
omap3_timer_hook.proc_nr_e = NONE;
omap3_timer_hook.irq = OMAP3_GPT1_IRQ;
put_irq_handler(&omap3_timer_hook, OMAP3_GPT1_IRQ, handler);
return 0;
}
void omap3_frclock_init(void)
{
u32_t tisr;
/* Stop timer */
mmio_clear(OMAP3_GPTIMER10_TCLR, OMAP3_TCLR_ST);
/* Use functional clock source for GPTIMER10 */
mmio_set(OMAP3_CM_CLKSEL_CORE, OMAP3_CLKSEL_GPT10);
/* Scale timer down to 13/8 = 1.625 Mhz to roughly get microsecond ticks */
/* The scale is computed as 2^(PTV+1). So if PTV == 2, we get 2^3 = 8.
*/
mmio_set(OMAP3_GPTIMER10_TCLR, (2 << OMAP3_TCLR_PTV));
/* Start and auto-reload at 0 */
mmio_write(OMAP3_GPTIMER10_TLDR, 0x0);
mmio_write(OMAP3_GPTIMER10_TCRR, 0x0);
/* Set up overflow interrupt */
tisr = OMAP3_TISR_MAT_IT_FLAG | OMAP3_TISR_OVF_IT_FLAG |
OMAP3_TISR_TCAR_IT_FLAG;
mmio_write(OMAP3_GPTIMER10_TISR, tisr); /* Clear interrupt status */
mmio_write(OMAP3_GPTIMER10_TIER, OMAP3_TIER_OVF_IT_ENA);
/* Start timer */
mmio_set(OMAP3_GPTIMER10_TCLR,
OMAP3_TCLR_OVF_TRG|OMAP3_TCLR_AR|OMAP3_TCLR_ST|OMAP3_TCLR_PRE);
}
void omap3_frclock_stop()
{
mmio_clear(OMAP3_GPTIMER10_TCLR, OMAP3_TCLR_ST);
}
void omap3_timer_init(unsigned freq)
{
u32_t tisr;
/* Stop timer */
mmio_clear(OMAP3_GPTIMER1_TCLR, OMAP3_TCLR_ST);
/* Use 32 KHz clock source for GPTIMER1 */
mmio_clear(OMAP3_CM_CLKSEL_WKUP, OMAP3_CLKSEL_GPT1);
/* Use 1-ms tick mode for GPTIMER1 TRM 16.2.4.2.1 */
mmio_write(OMAP3_GPTIMER1_TPIR, 232000);
mmio_write(OMAP3_GPTIMER1_TNIR, -768000);
mmio_write(OMAP3_GPTIMER1_TLDR, 0xffffffe0);
mmio_write(OMAP3_GPTIMER1_TCRR, 0xffffffe0);
/* Set up overflow interrupt */
tisr = OMAP3_TISR_MAT_IT_FLAG | OMAP3_TISR_OVF_IT_FLAG |
OMAP3_TISR_TCAR_IT_FLAG;
mmio_write(OMAP3_GPTIMER1_TISR, tisr); /* Clear interrupt status */
mmio_write(OMAP3_GPTIMER1_TIER, OMAP3_TIER_OVF_IT_ENA);
omap3_irq_unmask(OMAP3_GPT1_IRQ);
/* Start timer */
mmio_set(OMAP3_GPTIMER1_TCLR,
OMAP3_TCLR_OVF_TRG|OMAP3_TCLR_AR|OMAP3_TCLR_ST);
}
void omap3_timer_stop()
{
mmio_clear(OMAP3_GPTIMER1_TCLR, OMAP3_TCLR_ST);
}
static u32_t read_frc(void)
{
u32_t frc = *(u32_t *) ((char *) omap3_gptimer10_base + OMAP3_TCRR);
return frc;
}
static void frc_overflow_check(void)
{
static int prev_frc_valid;
static u32_t prev_frc;
u32_t cur_frc = read_frc();
if(prev_frc_valid && prev_frc > cur_frc)
high_frc++;
prev_frc = cur_frc;
prev_frc_valid = 1;
}
void omap3_timer_int_handler()
{
/* Clear all interrupts */
u32_t tisr;
tisr = OMAP3_TISR_MAT_IT_FLAG | OMAP3_TISR_OVF_IT_FLAG |
OMAP3_TISR_TCAR_IT_FLAG;
mmio_write(OMAP3_GPTIMER1_TISR, tisr);
frc_overflow_check();
}
/* Use the free running clock as TSC */
void read_tsc_64(u64_t *t)
{
u32_t now;
frc_overflow_check();
now = read_frc();
*t = (u64_t) now + (high_frc << 32);
}