*
* Copyright (C) 2000-2001 Deep Blue Solutions
* Copyright (C) 2002 Shane Nay (shane@minirl.com)
+ * Copyright (C) 2006-2007 Pavel Pisa (ppisa@pikron.com)
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
-#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/interrupt.h>
+#include <linux/irq.h>
#include <linux/time.h>
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
#include <asm/hardware.h>
#include <asm/io.h>
/* 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 struct clock_event_device clockevent_imx;
+static enum clock_event_mode clockevent_mode = CLOCK_EVT_MODE_UNUSED;
/*
* IRQ handler for the timer
*/
static irqreturn_t
-imx_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+imx_timer_interrupt(int irq, void *dev_id)
{
- write_seqlock(&xtime_lock);
+ struct clock_event_device *evt = &clockevent_imx;
+ uint32_t tstat;
+ irqreturn_t ret = IRQ_NONE;
/* clear the interrupt */
- if (IMX_TSTAT(TIMER_BASE))
- IMX_TSTAT(TIMER_BASE) = 0;
+ tstat = IMX_TSTAT(TIMER_BASE);
+ IMX_TSTAT(TIMER_BASE) = 0;
- timer_tick(regs);
- write_sequnlock(&xtime_lock);
+ if (tstat & TSTAT_COMP) {
+ evt->event_handler(evt);
+ ret = IRQ_HANDLED;
+ }
- return IRQ_HANDLED;
+ return ret;
}
static struct irqaction imx_timer_irq = {
.name = "i.MX Timer Tick",
- .flags = SA_INTERRUPT | SA_TIMER,
+ .flags = IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
.handler = imx_timer_interrupt,
};
/*
- * 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)
*/
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_TEN;
+}
+
+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,
+ .flags = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+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 int imx_set_next_event(unsigned long evt,
+ struct clock_event_device *unused)
+{
+ unsigned long tcmp;
+
+ tcmp = IMX_TCN(TIMER_BASE) + evt;
+ IMX_TCMP(TIMER_BASE) = tcmp;
+
+ return (int32_t)(tcmp - IMX_TCN(TIMER_BASE)) < 0 ? -ETIME : 0;
+}
+
+#ifdef DEBUG
+static const char *clock_event_mode_label[]={
+ [CLOCK_EVT_MODE_PERIODIC] = "CLOCK_EVT_MODE_PERIODIC",
+ [CLOCK_EVT_MODE_ONESHOT] = "CLOCK_EVT_MODE_ONESHOT",
+ [CLOCK_EVT_MODE_SHUTDOWN] = "CLOCK_EVT_MODE_SHUTDOWN",
+ [CLOCK_EVT_MODE_UNUSED] = "CLOCK_EVT_MODE_UNUSED"
+};
+#endif /*DEBUG*/
+
+static void imx_set_mode(enum clock_event_mode mode, struct clock_event_device *evt)
+{
+ unsigned long flags;
+
+ /*
+ * The timer interrupt generation is disabled at least
+ * for enough time to call imx_set_next_event()
+ */
+ local_irq_save(flags);
+ /* Disable interrupt in GPT module */
+ IMX_TCTL(TIMER_BASE) &= ~TCTL_IRQEN;
+ if (mode != clockevent_mode) {
+ /* Set event time into far-far future */
+ IMX_TCMP(TIMER_BASE) = IMX_TCN(TIMER_BASE) - 3;
+ /* Clear pending interrupt */
+ IMX_TSTAT(TIMER_BASE) &= ~TSTAT_COMP;
+ }
+
+#ifdef DEBUG
+ printk(KERN_INFO "imx_set_mode: changing mode from %s to %s\n",
+ clock_event_mode_label[clockevent_mode], clock_event_mode_label[mode]);
+#endif /*DEBUG*/
+
+ /* Remember timer mode */
+ clockevent_mode = mode;
+ local_irq_restore(flags);
+
+ switch (mode) {
+ case CLOCK_EVT_MODE_PERIODIC:
+ printk(KERN_ERR "imx_set_mode: Periodic mode is not supported for i.MX\n");
+ break;
+ case CLOCK_EVT_MODE_ONESHOT:
+ /*
+ * Do not put overhead of interrupt enable/disable into
+ * imx_set_next_event(), the core has about 4 minutes
+ * to call imx_set_next_event() or shutdown clock after
+ * mode switching
+ */
+ local_irq_save(flags);
+ IMX_TCTL(TIMER_BASE) |= TCTL_IRQEN;
+ local_irq_restore(flags);
+ break;
+ case CLOCK_EVT_MODE_SHUTDOWN:
+ case CLOCK_EVT_MODE_UNUSED:
+ case CLOCK_EVT_MODE_RESUME:
+ /* Left event sources disabled, no more interrupts appears */
+ break;
+ }
+}
+
+static struct clock_event_device clockevent_imx = {
+ .name = "imx_timer1",
+ .features = CLOCK_EVT_FEAT_ONESHOT,
+ .shift = 32,
+ .set_mode = imx_set_mode,
+ .set_next_event = imx_set_next_event,
+ .rating = 200,
+};
+
+static int __init imx_clockevent_init(void)
+{
+ clockevent_imx.mult = div_sc(imx_get_perclk1(), NSEC_PER_SEC,
+ clockevent_imx.shift);
+ clockevent_imx.max_delta_ns =
+ clockevent_delta2ns(0xfffffffe, &clockevent_imx);
+ clockevent_imx.min_delta_ns =
+ clockevent_delta2ns(0xf, &clockevent_imx);
+
+ clockevent_imx.cpumask = cpumask_of_cpu(0);
+
+ clockevents_register_device(&clockevent_imx);
+
+ return 0;
+}
+
+
+static void __init imx_timer_init(void)
+{
+ imx_timer_hardware_init();
+ imx_clocksource_init();
+
+ imx_clockevent_init();
/*
* Make irqs happen for the system timer
struct sys_timer imx_timer = {
.init = imx_timer_init,
- .offset = imx_gettimeoffset,
};
git://ftp.safe.ca / safe / jmp / linux-2.6 / blobdiff