Re: [Xenomai-core] preemptive doesn't work

[Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>]

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On 04/10/2012 11:21 AM, Roberto Bielli wrote:
> Hi Gilles,
> 
> here is my time.c

Though you have not made all the changes I suggested. Here is the time.c
I would use.

-- 
                                                                Gilles.

[-- Attachment #2: time.c --]
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/*
 *  linux/arch/arm/plat-mxc/time.c
 *
 *  Copyright (C) 2000-2001 Deep Blue Solutions
 *  Copyright (C) 2002 Shane Nay (shane@domain.hid)
 *  Copyright (C) 2006-2007 Pavel Pisa (ppisa@domain.hid)
 *  Copyright (C) 2008 Juergen Beisert (kernel@domain.hid)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 * MA 02110-1301, USA.
 */

#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/clockchips.h>
#include <linux/clk.h>

#include <mach/hardware.h>
#include <asm/mach/time.h>
#include <mach/common.h>

/* defines common for all i.MX */
#define MXC_TCTL		0x00
#define MXC_TCTL_TEN		(1 << 0)
#define MXC_TPRER		0x04

/* MX1, MX21, MX27 */
#define MX1_2_TCTL_CLK_PCLK1	(1 << 1)
#define MX1_2_TCTL_IRQEN	(1 << 4)
#define MX1_2_TCTL_FRR		(1 << 8)
#define MX1_2_TCMP		0x08
#define MX1_2_TCN		0x10
#define MX1_2_TSTAT		0x14

/* MX21, MX27 */
#define MX2_TSTAT_CAPT		(1 << 1)
#define MX2_TSTAT_COMP		(1 << 0)

/* MX31, MX35, MX25 */
#define MX3_TCTL_WAITEN		(1 << 3)
#define MX3_TCTL_CLK_IPG	(1 << 6)
#define MX3_TCTL_CLK_PER	(2 << 6)
#define MX3_TCTL_FRR		(1 << 9)
#define MX3_IR			0x0c
#define MX3_TSTAT		0x08
#define MX3_TSTAT_OF1		(1 << 0)
#define MX3_TCN			0x24
#define MX3_TCMP		0x10

#ifdef CONFIG_IPIPE
#ifdef CONFIG_NO_IDLE_HZ
#error "dynamic tick timer not yet supported with IPIPE"
#endif /* CONFIG_NO_IDLE_HZ */
int __ipipe_mach_timerint;
EXPORT_SYMBOL(__ipipe_mach_timerint);

int __ipipe_mach_timerstolen = 0;
EXPORT_SYMBOL(__ipipe_mach_timerstolen);

unsigned int __ipipe_mach_ticks_per_jiffy = LATCH;
EXPORT_SYMBOL(__ipipe_mach_ticks_per_jiffy);

static int mxc_timer_initialized;
static unsigned mxc_min_delay;

union tsc_reg {
#ifdef __BIG_ENDIAN
	struct {
		unsigned long high;
		unsigned long low;
	};
#else /* __LITTLE_ENDIAN */
	struct {
		unsigned long low;
		unsigned long high;
	};
#endif /* __LITTLE_ENDIAN */
	unsigned long long full;
};

#ifdef CONFIG_SMP
static union tsc_reg tsc[NR_CPUS];

void __ipipe_mach_get_tscinfo(struct __ipipe_tscinfo *info)
{
	info->type = IPIPE_TSC_TYPE_NONE;
}

#else /* !CONFIG_SMP */
static union tsc_reg *tsc;

void __ipipe_mach_get_tscinfo(struct __ipipe_tscinfo *info)
{
	info->type = IPIPE_TSC_TYPE_FREERUNNING;
	if (cpu_is_mx1()) {
#ifdef CONFIG_ARCH_MX1
		info->u.fr.counter = (unsigned *) (TIM1_BASE_ADDR + MX1_2_TCN);
#endif
	} else if (cpu_is_mx2()) {
#ifdef CONFIG_ARCH_MX2
		info->u.fr.counter = (unsigned *) (GPT1_BASE_ADDR + MX1_2_TCN);
#endif
	} else if (cpu_is_mx3() || cpu_is_mx25() ) {
#if defined CONFIG_ARCH_MX3 || defined CONFIG_ARCH_MX25
		info->u.fr.counter = (unsigned *) (GPT1_BASE_ADDR + MX3_TCN);
#endif
	}
	info->u.fr.mask = 0xffffffff;
	info->u.fr.tsc = &tsc->full;
}
#endif /* !CONFIG_SMP */

static void ipipe_mach_update_tsc(void);
#endif /* CONFIG_IPIPE */

#define timer_is_v2()	(cpu_is_mx3() || cpu_is_mx25() || cpu_is_mx5())

static struct clock_event_device clockevent_mxc;
static enum clock_event_mode clockevent_mode = CLOCK_EVT_MODE_UNUSED;

static void __iomem *timer_base;

static inline void gpt_irq_disable(void)
{
	unsigned int tmp;

	if (timer_is_v2())
		__raw_writel(0, timer_base + MX3_IR);
	else {
		tmp = __raw_readl(timer_base + MXC_TCTL);
		__raw_writel(tmp & ~MX1_2_TCTL_IRQEN, timer_base + MXC_TCTL);
	}
}

static inline void gpt_irq_enable(void)
{
	if (timer_is_v2())
		__raw_writel(1<<0, timer_base + MX3_IR);
	else {
		__raw_writel(__raw_readl(timer_base + MXC_TCTL) | MX1_2_TCTL_IRQEN,
			timer_base + MXC_TCTL);
	}
}

static void gpt_irq_acknowledge(void)
{
	if (!timer_is_v2()) {
		if (cpu_is_mx1())
			__raw_writel(0, timer_base + MX1_2_TSTAT);
		else
			__raw_writel(MX2_TSTAT_CAPT | MX2_TSTAT_COMP, timer_base + MX1_2_TSTAT);
	} else
		__raw_writel(MX3_TSTAT_OF1, timer_base + MX3_TSTAT);
}

static cycle_t timer_v1_get_cycles(struct clocksource *cs)
{
	return __raw_readl(timer_base + MX1_2_TCN);
}

static cycle_t timer_v2_get_cycles(struct clocksource *cs)
{
	return __raw_readl(timer_base + MX3_TCN);
}

static struct clocksource clocksource_mxc = {
	.name		= "mxc_timer1",
	.rating		= 200,
	.read		= timer_v1_get_cycles,
	.mask		= CLOCKSOURCE_MASK(32),
	.shift		= 20,
	.flags		= CLOCK_SOURCE_IS_CONTINUOUS,
};

static int __init mxc_clocksource_init(struct clk *timer_clk)
{
	unsigned int c = clk_get_rate(timer_clk);

	if (timer_is_v2())
		clocksource_mxc.read = timer_v2_get_cycles;

#ifdef CONFIG_IPIPE
	__ipipe_mach_ticks_per_jiffy = (c + HZ/2) / HZ;
#endif /* CONFIG_IPIPE */
	clocksource_mxc.mult = clocksource_hz2mult(c,
					clocksource_mxc.shift);
	clocksource_register(&clocksource_mxc);

	return 0;
}

/* clock event */

static int timer_v1_set_next_event(unsigned long evt,
			      struct clock_event_device *unused)
{
	unsigned long tcmp;

	tcmp = __raw_readl(timer_base + MX1_2_TCN) + evt;

	__raw_writel(tcmp, timer_base + MX1_2_TCMP);

	return (int)(tcmp - __raw_readl(timer_base + MX1_2_TCN)) < 0 ?
				-ETIME : 0;
}

static int timer_v2_set_next_event(unsigned long evt,
			      struct clock_event_device *unused)
{
	unsigned long tcmp;

	tcmp = __raw_readl(timer_base + MX3_TCN) + evt;

	__raw_writel(tcmp, timer_base + MX3_TCMP);

	return (int)(tcmp - __raw_readl(timer_base + MX3_TCN)) < 0 ? -ETIME : 0;
}

#ifdef DEBUG
static inline const char *clock_event_mode_label(enum clock_event_mode mode)
{
	switch (mode) {
	case CLOCK_EVT_MODE_PERIODIC:
		return "CLOCK_EVT_MODE_PERIODIC";
	case CLOCK_EVT_MODE_ONESHOT:
		return "CLOCK_EVT_MODE_ONESHOT";
	case CLOCK_EVT_MODE_SHUTDOWN:
		return "CLOCK_EVT_MODE_SHUTDOWN";
	case CLOCK_EVT_MODE_UNUSED:
		return "CLOCK_EVT_MODE_UNUSED";
	case CLOCK_EVT_MODE_RESUME:
		return "CLOCK_EVT_MODE_RESUME";
	}
	return "UNKNOWN";
};
#endif /* DEBUG */

static void mxc_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 mxc_set_next_event()
	 */
	local_irq_save(flags);

	/* Disable interrupt in GPT module */
	gpt_irq_disable();

	if (mode != clockevent_mode) {
		/* Set event time into far-far future */
		if (timer_is_v2())
			__raw_writel(__raw_readl(timer_base + MX3_TCN) - 3,
					timer_base + MX3_TCMP);
		else
			__raw_writel(__raw_readl(timer_base + MX1_2_TCN) - 3,
					timer_base + MX1_2_TCMP);

		/* Clear pending interrupt */
		gpt_irq_acknowledge();
	}

#ifdef DEBUG
	printk(KERN_INFO "mxc_set_mode: changing mode from %s[%d] to %s[%d]\n",
		clock_event_mode_label(clockevent_mode), clockevent_mode,
		clock_event_mode_label(mode), mode);
#endif /* DEBUG */

	/* Remember timer mode */
	clockevent_mode = mode;
	local_irq_restore(flags);
	switch (mode)
	{
	case CLOCK_EVT_MODE_PERIODIC:
		printk(KERN_ERR "mxc_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
	 * mxc_set_next_event(), the core has about 4 minutes
	 * to call mxc_set_next_event() or shutdown clock after
	 * mode switching
	 */
		local_irq_save(flags);
		gpt_irq_enable();
		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 appear */
		break;
	}
}

/*
 * IRQ handler for the timer
 */
static irqreturn_t mxc_timer_interrupt(int irq, void *dev_id)
{
	struct clock_event_device *evt = &clockevent_mxc;
	uint32_t tstat;
	unsigned long reg;

#ifndef CONFIG_IPIPE
	if (timer_is_v2())
		tstat = __raw_readl(timer_base + MX3_TSTAT);
	else
		tstat = __raw_readl(timer_base + MX1_2_TSTAT);

	gpt_irq_acknowledge();
#else /* !CONFIG_IPIPE */

	ipipe_mach_update_tsc();

#endif /* !CONFIG_IPIPE */

	evt->event_handler(evt);

	return IRQ_HANDLED;
}

static struct irqaction mxc_timer_irq = {
	.name		= "i.MX Timer Tick",
	.flags		= IRQF_DISABLED | IRQF_TIMER | IRQF_IRQPOLL,
	.handler	= mxc_timer_interrupt,
};

static struct clock_event_device clockevent_mxc = {
	.name		= "mxc_timer1",
	.features	= CLOCK_EVT_FEAT_ONESHOT,
	.shift		= 32,
	.set_mode	= mxc_set_mode,
	.set_next_event	= timer_v1_set_next_event,
	.rating		= 200,
};

static int __init mxc_clockevent_init(struct clk *timer_clk)
{
	unsigned long c = clk_get_rate(timer_clk);

	printk(KERN_DEBUG "%s: timer clk rate is %lu.%03luMHz\n", __FUNCTION__,
		c / 1000000, c / 1000 % 1000);

	if (timer_is_v2())
		clockevent_mxc.set_next_event = timer_v2_set_next_event;

	clockevent_mxc.mult = div_sc(c, NSEC_PER_SEC,
					clockevent_mxc.shift);
	clockevent_mxc.max_delta_ns =
			clockevent_delta2ns(0xfffffffe, &clockevent_mxc);
	clockevent_mxc.min_delta_ns =
			clockevent_delta2ns(0xff, &clockevent_mxc);

	clockevent_mxc.cpumask = cpumask_of(0);

	clockevents_register_device(&clockevent_mxc);

	return 0;
}

void __init mxc_timer_init(struct clk *timer_clk, void __iomem *base, int irq)
{
	uint32_t tctl_val;

	clk_enable(timer_clk);

	timer_base = base;

	/*
	 * Initialise to a known state (all timers off, and timing reset)
	 */

	__raw_writel(0, timer_base + MXC_TCTL);
	__raw_writel(0, timer_base + MXC_TPRER); /* see datasheet note */

	if (timer_is_v2())
		tctl_val = MX3_TCTL_CLK_IPG | MX3_TCTL_FRR | MX3_TCTL_WAITEN | MXC_TCTL_TEN;
	else
		tctl_val = MX1_2_TCTL_FRR | MX1_2_TCTL_CLK_PCLK1 | MXC_TCTL_TEN;

	__raw_writel(tctl_val, timer_base + MXC_TCTL);

	/* init and register the timer to the framework */
	mxc_clocksource_init(timer_clk);
	mxc_clockevent_init(timer_clk);

	/* Make irqs happen */
	setup_irq(irq, &mxc_timer_irq);

#ifdef CONFIG_IPIPE
	__ipipe_mach_timerint = irq;
#ifndef CONFIG_SMP
	tsc = (union tsc_reg *) __ipipe_tsc_area;
	barrier();
#endif /* CONFIG_SMP */

	mxc_min_delay = 2 * ((ipipe_cpu_freq() + 500000) / 1000000) ?: 1;
	if (mxc_min_delay == 0)
	{
		mxc_min_delay = 1;
	}

	printk(  KERN_INFO "mxc_min_delay = %d\n", mxc_min_delay );
	mxc_timer_initialized = 1;
#endif /* CONFIG_IPIPE */
}

#ifdef CONFIG_IPIPE
int __ipipe_check_tickdev(const char *devname)
{
	return !strcmp(devname, clockevent_mxc.name);
}

void __ipipe_mach_acktimer(void)
{
	uint32_t tstat;

	if (timer_is_v2())
		tstat = __raw_readl(timer_base + MX3_TSTAT);
	else
		tstat = __raw_readl(timer_base + MX1_2_TSTAT);

	gpt_irq_acknowledge();
}

static void ipipe_mach_update_tsc(void)
{
	union tsc_reg *local_tsc;
	unsigned long stamp, flags;

	local_irq_save_hw(flags);
	local_tsc = &tsc[ipipe_processor_id()];
	if (!timer_is_v2())
		stamp = __raw_readl(timer_base + MX1_2_TCN);
	else
		stamp = __raw_readl(timer_base + MX3_TCN);
	if (unlikely(stamp < local_tsc->low))
		/* 32 bit counter wrapped, increment high word. */
		local_tsc->high++;
	local_tsc->low = stamp;
	local_irq_restore_hw(flags);
}

notrace unsigned long long __ipipe_mach_get_tsc(void)
{
	if (likely(mxc_timer_initialized)) {
		union tsc_reg *local_tsc, result;
		unsigned long stamp;

		local_tsc = &tsc[ipipe_processor_id()];

		if (!timer_is_v2())  {
			__asm__ ("ldmia %1, %M0\n"
				 : "=r"(result.full), "+&r"(local_tsc)
				 : "m"(*local_tsc));
			barrier();
			stamp = __raw_readl(timer_base + MX1_2_TCN);
		} else {
			__asm__ ("ldmia %1, %M0\n"
				 : "=r"(result.full), "+&r"(local_tsc)
				 : "m"(*local_tsc));
			barrier();
			stamp = __raw_readl(timer_base + MX3_TCN);
		}
		if (unlikely(stamp < result.low))
			/* 32 bit counter wrapped, increment high word. */
			result.high++;
		result.low = stamp;

		return result.full;
	}

	return 0;
}
EXPORT_SYMBOL(__ipipe_mach_get_tsc);

/*
 * Reprogram the timer
 */

void __ipipe_mach_set_dec(unsigned long delay)
{
	if (delay > mxc_min_delay) {
		unsigned long flags;

		local_irq_save_hw(flags);
		if (!time_is_v2())
			timer_v1_set_next_event(delay, NULL);
		else
			timer_v2_set_next_event(delay, NULL);
		local_irq_restore_hw(flags);
	} else
		ipipe_trigger_irq(__ipipe_mach_timerint);
}
EXPORT_SYMBOL(__ipipe_mach_set_dec);

void __ipipe_mach_release_timer(void)
{
	mxc_set_mode(clockevent_mxc.mode, &clockevent_mxc);
	if (clockevent_mxc.mode == CLOCK_EVT_MODE_ONESHOT)
		clockevent_mxc.set_next_event(LATCH, &clockevent_mxc);
}
EXPORT_SYMBOL(__ipipe_mach_release_timer);

unsigned long __ipipe_mach_get_dec(void)
{
	if (!time_is_v2())
		return __raw_readl(timer_base + MX1_2_TCMP)
			- __raw_readl(timer_base + MX1_2_TCN);
	else
		return __raw_readl(timer_base + MX3_TCMP)
			- __raw_readl(timer_base + MX3_TCN);
}
#endif /* CONFIG_IPIPE */