From 86987d5bf4db7850a8dfb073c6a3506d4e0d2bcc Mon Sep 17 00:00:00 2001 From: Pavel Pisa Date: Wed, 6 Dec 2006 17:19:44 +0100 Subject: [ARM] 3991/1: i.MX/MX1 high resolution time source Enhanced resolution for time measurement functions. Signed-off-by: Pavel Pisa Signed-off-by: Sascha Hauer Signed-off-by: Russell King --- arch/arm/mach-imx/time.c | 86 ++++++++++++++++++++++++++++-------------------- 1 file changed, 50 insertions(+), 36 deletions(-) (limited to 'arch/arm/mach-imx') diff --git a/arch/arm/mach-imx/time.c b/arch/arm/mach-imx/time.c index 8ae4a2c5066..40039b2a90b 100644 --- a/arch/arm/mach-imx/time.c +++ b/arch/arm/mach-imx/time.c @@ -14,6 +14,7 @@ #include #include #include +#include #include #include @@ -24,33 +25,7 @@ /* Use timer 1 as system timer */ #define TIMER_BASE IMX_TIM1_BASE -/* - * Returns number of us since last clock interrupt. Note that interrupts - * will have been disabled by do_gettimeoffset() - */ -static unsigned long imx_gettimeoffset(void) -{ - unsigned long ticks; - - /* - * Get the current number of ticks. Note that there is a race - * condition between us reading the timer and checking for - * an interrupt. We get around this by ensuring that the - * counter has not reloaded between our two reads. - */ - ticks = IMX_TCN(TIMER_BASE); - - /* - * Interrupt pending? If so, we've reloaded once already. - */ - if (IMX_TSTAT(TIMER_BASE) & TSTAT_COMP) - ticks += LATCH; - - /* - * Convert the ticks to usecs - */ - return (1000000 / CLK32) * ticks; -} +static unsigned long evt_diff; /* * IRQ handler for the timer @@ -58,14 +33,23 @@ static unsigned long imx_gettimeoffset(void) static irqreturn_t imx_timer_interrupt(int irq, void *dev_id) { - write_seqlock(&xtime_lock); + uint32_t tstat; /* clear the interrupt */ - if (IMX_TSTAT(TIMER_BASE)) - IMX_TSTAT(TIMER_BASE) = 0; + tstat = IMX_TSTAT(TIMER_BASE); + IMX_TSTAT(TIMER_BASE) = 0; + + if (tstat & TSTAT_COMP) { + do { + + write_seqlock(&xtime_lock); + timer_tick(); + write_sequnlock(&xtime_lock); + IMX_TCMP(TIMER_BASE) += evt_diff; - timer_tick(); - write_sequnlock(&xtime_lock); + } while (unlikely((int32_t)(IMX_TCMP(TIMER_BASE) + - IMX_TCN(TIMER_BASE)) < 0)); + } return IRQ_HANDLED; } @@ -77,9 +61,9 @@ static struct irqaction imx_timer_irq = { }; /* - * Set up timer interrupt, and return the current time in seconds. + * Set up timer hardware into expected mode and state. */ -static void __init imx_timer_init(void) +static void __init imx_timer_hardware_init(void) { /* * Initialise to a known state (all timers off, and timing reset) @@ -87,7 +71,38 @@ static void __init imx_timer_init(void) IMX_TCTL(TIMER_BASE) = 0; IMX_TPRER(TIMER_BASE) = 0; IMX_TCMP(TIMER_BASE) = LATCH - 1; - IMX_TCTL(TIMER_BASE) = TCTL_CLK_32 | TCTL_IRQEN | TCTL_TEN; + + IMX_TCTL(TIMER_BASE) = TCTL_FRR | TCTL_CLK_PCLK1 | TCTL_IRQEN | TCTL_TEN; + evt_diff = LATCH; +} + +cycle_t imx_get_cycles(void) +{ + return IMX_TCN(TIMER_BASE); +} + +static struct clocksource clocksource_imx = { + .name = "imx_timer1", + .rating = 200, + .read = imx_get_cycles, + .mask = 0xFFFFFFFF, + .shift = 20, + .is_continuous = 1, +}; + +static int __init imx_clocksource_init(void) +{ + clocksource_imx.mult = + clocksource_hz2mult(imx_get_perclk1(), clocksource_imx.shift); + clocksource_register(&clocksource_imx); + + return 0; +} + +static void __init imx_timer_init(void) +{ + imx_timer_hardware_init(); + imx_clocksource_init(); /* * Make irqs happen for the system timer @@ -97,5 +112,4 @@ static void __init imx_timer_init(void) struct sys_timer imx_timer = { .init = imx_timer_init, - .offset = imx_gettimeoffset, }; -- cgit v1.2.3