[ARM] 4374/3: i.MX/MX1 clock event source
Support clock event source based on i.MX general purpose timer in free running timer mode. Signed-off-by: Pavel Pisa <pisa@cmp.felk.cvut.cz> Acked-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: Sascha Hauer <s.hauer@pengutronix.de> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>hifive-unleashed-5.1
Pavel Pisa
Russell King
parent
b3e6a508ed
commit
89bba43514
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@ -242,6 +242,8 @@ config ARCH_H720X
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config ARCH_IMX
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bool "IMX"
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select GENERIC_GPIO
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select GENERIC_TIME
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select GENERIC_CLOCKEVENTS
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help
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Support for Motorola's i.MX family of processors (MX1, MXL).
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@ -3,6 +3,7 @@
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*
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* Copyright (C) 2000-2001 Deep Blue Solutions
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* Copyright (C) 2002 Shane Nay (shane@minirl.com)
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* Copyright (C) 2006-2007 Pavel Pisa (ppisa@pikron.com)
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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@ -15,6 +16,7 @@
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#include <linux/irq.h>
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#include <linux/time.h>
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#include <linux/clocksource.h>
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#include <linux/clockchips.h>
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#include <asm/hardware.h>
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#include <asm/io.h>
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@ -25,7 +27,8 @@
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/* Use timer 1 as system timer */
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#define TIMER_BASE IMX_TIM1_BASE
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static unsigned long evt_diff;
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static struct clock_event_device clockevent_imx;
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static enum clock_event_mode clockevent_mode = CLOCK_EVT_MODE_UNUSED;
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/*
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* IRQ handler for the timer
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@ -33,25 +36,20 @@ static unsigned long evt_diff;
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static irqreturn_t
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imx_timer_interrupt(int irq, void *dev_id)
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{
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struct clock_event_device *evt = &clockevent_imx;
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uint32_t tstat;
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irqreturn_t ret = IRQ_NONE;
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/* clear the interrupt */
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tstat = IMX_TSTAT(TIMER_BASE);
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IMX_TSTAT(TIMER_BASE) = 0;
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if (tstat & TSTAT_COMP) {
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do {
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write_seqlock(&xtime_lock);
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timer_tick();
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write_sequnlock(&xtime_lock);
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IMX_TCMP(TIMER_BASE) += evt_diff;
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} while (unlikely((int32_t)(IMX_TCMP(TIMER_BASE)
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- IMX_TCN(TIMER_BASE)) < 0));
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evt->event_handler(evt);
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ret = IRQ_HANDLED;
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}
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return IRQ_HANDLED;
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return ret;
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}
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static struct irqaction imx_timer_irq = {
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@ -70,10 +68,8 @@ static void __init imx_timer_hardware_init(void)
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*/
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IMX_TCTL(TIMER_BASE) = 0;
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IMX_TPRER(TIMER_BASE) = 0;
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IMX_TCMP(TIMER_BASE) = LATCH - 1;
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IMX_TCTL(TIMER_BASE) = TCTL_FRR | TCTL_CLK_PCLK1 | TCTL_IRQEN | TCTL_TEN;
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evt_diff = LATCH;
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IMX_TCTL(TIMER_BASE) = TCTL_FRR | TCTL_CLK_PCLK1 | TCTL_TEN;
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}
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cycle_t imx_get_cycles(void)
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@ -99,11 +95,108 @@ static int __init imx_clocksource_init(void)
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return 0;
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}
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static int imx_set_next_event(unsigned long evt,
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struct clock_event_device *unused)
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{
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unsigned long tcmp;
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tcmp = IMX_TCN(TIMER_BASE) + evt;
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IMX_TCMP(TIMER_BASE) = tcmp;
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return (int32_t)(tcmp - IMX_TCN(TIMER_BASE)) < 0 ? -ETIME : 0;
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}
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#ifdef DEBUG
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static const char *clock_event_mode_label[]={
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[CLOCK_EVT_MODE_PERIODIC] = "CLOCK_EVT_MODE_PERIODIC",
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[CLOCK_EVT_MODE_ONESHOT] = "CLOCK_EVT_MODE_ONESHOT",
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[CLOCK_EVT_MODE_SHUTDOWN] = "CLOCK_EVT_MODE_SHUTDOWN",
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[CLOCK_EVT_MODE_UNUSED] = "CLOCK_EVT_MODE_UNUSED"
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};
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#endif /*DEBUG*/
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static void imx_set_mode(enum clock_event_mode mode, struct clock_event_device *evt)
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{
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unsigned long flags;
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/*
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* The timer interrupt generation is disabled at least
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* for enough time to call imx_set_next_event()
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*/
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local_irq_save(flags);
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/* Disable interrupt in GPT module */
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IMX_TCTL(TIMER_BASE) &= ~TCTL_IRQEN;
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if (mode != clockevent_mode) {
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/* Set event time into far-far future */
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IMX_TCMP(TIMER_BASE) = IMX_TCN(TIMER_BASE) - 3;
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/* Clear pending interrupt */
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IMX_TSTAT(TIMER_BASE) &= ~TSTAT_COMP;
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}
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#ifdef DEBUG
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printk(KERN_INFO "imx_set_mode: changing mode from %s to %s\n",
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clock_event_mode_label[clockevent_mode], clock_event_mode_label[mode]);
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#endif /*DEBUG*/
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/* Remember timer mode */
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clockevent_mode = mode;
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local_irq_restore(flags);
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switch (mode) {
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case CLOCK_EVT_MODE_PERIODIC:
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printk(KERN_ERR "imx_set_mode: Periodic mode is not supported for i.MX\n");
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break;
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case CLOCK_EVT_MODE_ONESHOT:
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/*
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* Do not put overhead of interrupt enable/disable into
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* imx_set_next_event(), the core has about 4 minutes
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* to call imx_set_next_event() or shutdown clock after
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* mode switching
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*/
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local_irq_save(flags);
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IMX_TCTL(TIMER_BASE) |= TCTL_IRQEN;
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local_irq_restore(flags);
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break;
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case CLOCK_EVT_MODE_SHUTDOWN:
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case CLOCK_EVT_MODE_UNUSED:
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/* Left event sources disabled, no more interrupts appears */
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break;
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}
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}
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static struct clock_event_device clockevent_imx = {
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.name = "imx_timer1",
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.features = CLOCK_EVT_FEAT_ONESHOT,
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.shift = 32,
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.set_mode = imx_set_mode,
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.set_next_event = imx_set_next_event,
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.rating = 200,
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};
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static int __init imx_clockevent_init(void)
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{
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clockevent_imx.mult = div_sc(imx_get_perclk1(), NSEC_PER_SEC,
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clockevent_imx.shift);
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clockevent_imx.max_delta_ns =
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clockevent_delta2ns(0xfffffffe, &clockevent_imx);
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clockevent_imx.min_delta_ns =
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clockevent_delta2ns(0xf, &clockevent_imx);
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clockevent_imx.cpumask = cpumask_of_cpu(0);
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clockevents_register_device(&clockevent_imx);
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return 0;
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}
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static void __init imx_timer_init(void)
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{
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imx_timer_hardware_init();
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imx_clocksource_init();
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imx_clockevent_init();
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/*
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* Make irqs happen for the system timer
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*/
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