ipipe.c

/* -*- linux-c -*-
 * linux/arch/blackfin/kernel/ipipe.c
 *
 * Copyright (C) 2005-2007 Philippe Gerum.
 *
 * 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, Inc., 675 Mass Ave, Cambridge MA 02139,
 * USA; 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 * Architecture-dependent I-pipe support for the Blackfin.
 */

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/percpu.h>
#include <linux/bitops.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/kthread.h>
#include <asm/unistd.h>
#include <asm/system.h>
#include <asm/atomic.h>
#include <asm/io.h>

static int create_irq_threads;

DEFINE_PER_CPU(struct pt_regs, __ipipe_tick_regs);

static DEFINE_PER_CPU(unsigned long, pending_irqthread_mask);

static DEFINE_PER_CPU(int [IVG13 + 1], pending_irq_count);

asmlinkage void asm_do_IRQ(unsigned int irq, struct pt_regs *regs);

static void __ipipe_no_irqtail(void);

unsigned long __ipipe_irq_tail_hook = (unsigned long)&__ipipe_no_irqtail;
EXPORT_SYMBOL(__ipipe_irq_tail_hook);

unsigned long __ipipe_core_clock;
EXPORT_SYMBOL(__ipipe_core_clock);

unsigned long __ipipe_freq_scale;
EXPORT_SYMBOL(__ipipe_freq_scale);

atomic_t __ipipe_irq_lvdepth[IVG15 + 1];

unsigned long __ipipe_irq_lvmask = __all_masked_irq_flags;
EXPORT_SYMBOL(__ipipe_irq_lvmask);

static void __ipipe_ack_irq(unsigned irq, struct irq_desc *desc)
{
	desc->ipipe_ack(irq, desc);
}

/*
 * __ipipe_enable_pipeline() -- We are running on the boot CPU, hw
 * interrupts are off, and secondary CPUs are still lost in space.
 */
void __ipipe_enable_pipeline(void)
{
	unsigned irq;

	__ipipe_core_clock = get_cclk(); /* Fetch this once. */
	__ipipe_freq_scale = 1000000000UL / __ipipe_core_clock;

	for (irq = 0; irq < NR_IRQS; ++irq)
		ipipe_virtualize_irq(ipipe_root_domain,
				     irq,
				     (ipipe_irq_handler_t)&asm_do_IRQ,
				     NULL,
				     &__ipipe_ack_irq,
				     IPIPE_HANDLE_MASK | IPIPE_PASS_MASK);
}

/*
 * __ipipe_handle_irq() -- IPIPE's generic IRQ handler. An optimistic
 * interrupt protection log is maintained here for each domain. Hw
 * interrupts are masked on entry.
 */
void __ipipe_handle_irq(unsigned irq, struct pt_regs *regs)
{
	struct ipipe_domain *this_domain, *next_domain;
	struct list_head *head, *pos;
	int m_ack, s = -1;

	/*
	 * Software-triggered IRQs do not need any ack.  The contents
	 * of the register frame should only be used when processing
	 * the timer interrupt, but not for handling any other
	 * interrupt.
	 */
	m_ack = (regs == NULL || irq == IRQ_SYSTMR || irq == IRQ_CORETMR);

	this_domain = ipipe_current_domain;

	if (unlikely(test_bit(IPIPE_STICKY_FLAG, &this_domain->irqs[irq].control)))
		head = &this_domain->p_link;
	else {
		head = __ipipe_pipeline.next;
		next_domain = list_entry(head, struct ipipe_domain, p_link);
		if (likely(test_bit(IPIPE_WIRED_FLAG, &next_domain->irqs[irq].control))) {
			if (!m_ack && next_domain->irqs[irq].acknowledge != NULL)
				next_domain->irqs[irq].acknowledge(irq, irq_desc + irq);
			if (test_bit(IPIPE_ROOTLOCK_FLAG, &ipipe_root_domain->flags))
				s = __test_and_set_bit(IPIPE_STALL_FLAG,
						       &ipipe_root_cpudom_var(status));
			__ipipe_dispatch_wired(next_domain, irq);
				goto finalize;
			return;
		}
	}

	/* Ack the interrupt. */

	pos = head;

	while (pos != &__ipipe_pipeline) {
		next_domain = list_entry(pos, struct ipipe_domain, p_link);
		/*
		 * For each domain handling the incoming IRQ, mark it
		 * as pending in its log.
		 */
		if (test_bit(IPIPE_HANDLE_FLAG, &next_domain->irqs[irq].control)) {
			/*
			 * Domains that handle this IRQ are polled for
			 * acknowledging it by decreasing priority
			 * order. The interrupt must be made pending
			 * _first_ in the domain's status flags before
			 * the PIC is unlocked.
			 */
			__ipipe_set_irq_pending(next_domain, irq);

			if (!m_ack && next_domain->irqs[irq].acknowledge != NULL) {
				next_domain->irqs[irq].acknowledge(irq, irq_desc + irq);
				m_ack = 1;
			}
		}

		/*
		 * If the domain does not want the IRQ to be passed
		 * down the interrupt pipe, exit the loop now.
		 */
		if (!test_bit(IPIPE_PASS_FLAG, &next_domain->irqs[irq].control))
			break;

		pos = next_domain->p_link.next;
	}

	/*
	 * Now walk the pipeline, yielding control to the highest
	 * priority domain that has pending interrupt(s) or
	 * immediately to the current domain if the interrupt has been
	 * marked as 'sticky'. This search does not go beyond the
	 * current domain in the pipeline. We also enforce the
	 * additional root stage lock (blackfin-specific). */

	if (test_bit(IPIPE_ROOTLOCK_FLAG, &ipipe_root_domain->flags))
		s = __test_and_set_bit(IPIPE_STALL_FLAG,
				       &ipipe_root_cpudom_var(status));
finalize:

	__ipipe_walk_pipeline(head);

	if (!s)
		__clear_bit(IPIPE_STALL_FLAG,
			    &ipipe_root_cpudom_var(status));
}

int __ipipe_check_root(void)
{
	return ipipe_root_domain_p;
}

void __ipipe_enable_irqdesc(struct ipipe_domain *ipd, unsigned irq)
{
	struct irq_desc *desc = irq_desc + irq;
	int prio = desc->ic_prio;

	desc->depth = 0;
	if (ipd != &ipipe_root &&
	    atomic_inc_return(&__ipipe_irq_lvdepth[prio]) == 1)
		__set_bit(prio, &__ipipe_irq_lvmask);
}
EXPORT_SYMBOL(__ipipe_enable_irqdesc);

void __ipipe_disable_irqdesc(struct ipipe_domain *ipd, unsigned irq)
{
	struct irq_desc *desc = irq_desc + irq;
	int prio = desc->ic_prio;

	if (ipd != &ipipe_root &&
	    atomic_dec_and_test(&__ipipe_irq_lvdepth[prio]))
		__clear_bit(prio, &__ipipe_irq_lvmask);
}
EXPORT_SYMBOL(__ipipe_disable_irqdesc);

void __ipipe_stall_root_raw(void)
{
	/*
	 * This code is called by the ins{bwl} routines (see
	 * arch/blackfin/lib/ins.S), which are heavily used by the
	 * network stack. It masks all interrupts but those handled by
	 * non-root domains, so that we keep decent network transfer
	 * rates for Linux without inducing pathological jitter for
	 * the real-time domain.
	 */
	__asm__ __volatile__ ("sti %0;" : : "d"(__ipipe_irq_lvmask));

	__set_bit(IPIPE_STALL_FLAG,
		  &ipipe_root_cpudom_var(status));
}

void __ipipe_unstall_root_raw(void)
{
	__clear_bit(IPIPE_STALL_FLAG,
		    &ipipe_root_cpudom_var(status));

	__asm__ __volatile__ ("sti %0;" : : "d"(bfin_irq_flags));
}

int __ipipe_syscall_root(struct pt_regs *regs)
{
	unsigned long flags;

	/* We need to run the IRQ tail hook whenever we don't
	 * propagate a syscall to higher domains, because we know that
	 * important operations might be pending there (e.g. Xenomai
	 * deferred rescheduling). */

	if (!__ipipe_syscall_watched_p(current, regs->orig_p0)) {
		void (*hook)(void) = (void (*)(void))__ipipe_irq_tail_hook;
		hook();
		return 0;
	}

	/*
	 * This routine either returns:
	 * 0 -- if the syscall is to be passed to Linux;
	 * 1 -- if the syscall should not be passed to Linux, and no
	 * tail work should be performed;
	 * -1 -- if the syscall should not be passed to Linux but the
	 * tail work has to be performed (for handling signals etc).
	 */

	if (__ipipe_event_monitored_p(IPIPE_EVENT_SYSCALL) &&
	    __ipipe_dispatch_event(IPIPE_EVENT_SYSCALL, regs) > 0) {
		if (ipipe_root_domain_p && !in_atomic()) {
			/*
			 * Sync pending VIRQs before _TIF_NEED_RESCHED
			 * is tested.
			 */
			local_irq_save_hw(flags);
			if ((ipipe_root_cpudom_var(irqpend_himask) & IPIPE_IRQMASK_VIRT) != 0)
				__ipipe_sync_pipeline(IPIPE_IRQMASK_VIRT);
			local_irq_restore_hw(flags);
			return -1;
		}
		return 1;
	}

	return 0;
}

unsigned long ipipe_critical_enter(void (*syncfn) (void))
{
	unsigned long flags;

	local_irq_save_hw(flags);

	return flags;
}

void ipipe_critical_exit(unsigned long flags)
{
	local_irq_restore_hw(flags);
}

static void __ipipe_no_irqtail(void)
{
}

int ipipe_get_sysinfo(struct ipipe_sysinfo *info)
{
	info->ncpus = num_online_cpus();
	info->cpufreq = ipipe_cpu_freq();
	info->archdep.tmirq = IPIPE_TIMER_IRQ;
	info->archdep.tmfreq = info->cpufreq;

	return 0;
}

/*
 * ipipe_trigger_irq() -- Push the interrupt at front of the pipeline
 * just like if it has been actually received from a hw source. Also
 * works for virtual interrupts.
 */
int ipipe_trigger_irq(unsigned irq)
{
	unsigned long flags;

	if (irq >= IPIPE_NR_IRQS ||
	    (ipipe_virtual_irq_p(irq)
	     && !test_bit(irq - IPIPE_VIRQ_BASE, &__ipipe_virtual_irq_map)))
		return -EINVAL;

	local_irq_save_hw(flags);

	__ipipe_handle_irq(irq, NULL);

	local_irq_restore_hw(flags);

	return 1;
}

/* Move Linux IRQ to threads. */

static int do_irqd(void *__desc)
{
	struct irq_desc *desc = __desc;
	unsigned irq = desc - irq_desc;
	int thrprio = desc->thr_prio;
	int thrmask = 1 << thrprio;
	int cpu = smp_processor_id();
	cpumask_t cpumask;

	sigfillset(&current->blocked);
	current->flags |= PF_NOFREEZE;
	cpumask = cpumask_of_cpu(cpu);
	set_cpus_allowed(current, cpumask);
	ipipe_setscheduler_root(current, SCHED_FIFO, 50 + thrprio);

	while (!kthread_should_stop()) {
		local_irq_disable();
		if (!(desc->status & IRQ_SCHEDULED)) {
			set_current_state(TASK_INTERRUPTIBLE);
resched:
			local_irq_enable();
			schedule();
			local_irq_disable();
		}
		__set_current_state(TASK_RUNNING);
		/*
		 * If higher priority interrupt servers are ready to
		 * run, reschedule immediately. We need this for the
		 * GPIO demux IRQ handler to unmask the interrupt line
		 * _last_, after all GPIO IRQs have run.
		 */
		if (per_cpu(pending_irqthread_mask, cpu) & ~(thrmask|(thrmask-1)))
			goto resched;
		if (--per_cpu(pending_irq_count[thrprio], cpu) == 0)
			per_cpu(pending_irqthread_mask, cpu) &= ~thrmask;
		desc->status &= ~IRQ_SCHEDULED;
		desc->thr_handler(irq, &__raw_get_cpu_var(__ipipe_tick_regs));
		local_irq_enable();
	}
	__set_current_state(TASK_RUNNING);
	return 0;
}

static void kick_irqd(unsigned irq, void *cookie)
{
	struct irq_desc *desc = irq_desc + irq;
	int thrprio = desc->thr_prio;
	int thrmask = 1 << thrprio;
	int cpu = smp_processor_id();

	if (!(desc->status & IRQ_SCHEDULED)) {
		desc->status |= IRQ_SCHEDULED;
		per_cpu(pending_irqthread_mask, cpu) |= thrmask;
		++per_cpu(pending_irq_count[thrprio], cpu);
		wake_up_process(desc->thread);
	}
}

int ipipe_start_irq_thread(unsigned irq, struct irq_desc *desc)
{
	if (desc->thread || !create_irq_threads)
		return 0;

	desc->thread = kthread_create(do_irqd, desc, "IRQ %d", irq);
	if (desc->thread == NULL) {
		printk(KERN_ERR "irqd: could not create IRQ thread %d!\n", irq);
		return -ENOMEM;
	}

	wake_up_process(desc->thread);

	desc->thr_handler = ipipe_root_domain->irqs[irq].handler;
	ipipe_root_domain->irqs[irq].handler = &kick_irqd;

	return 0;
}

void __init ipipe_init_irq_threads(void)
{
	unsigned irq;
	struct irq_desc *desc;

	create_irq_threads = 1;

	for (irq = 0; irq < NR_IRQS; irq++) {
		desc = irq_desc + irq;
		if (desc->action != NULL ||
			(desc->status & IRQ_NOREQUEST) != 0)
			ipipe_start_irq_thread(irq, desc);
	}
}

EXPORT_SYMBOL(show_stack);

#ifdef CONFIG_IPIPE_TRACE_MCOUNT
void notrace _mcount(void);
EXPORT_SYMBOL(_mcount);
#endif /* CONFIG_IPIPE_TRACE_MCOUNT */