/* MN10300 Arch-specific interrupt handling
 *
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public Licence
 * as published by the Free Software Foundation; either version
 * 2 of the Licence, or (at your option) any later version.
 */
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/kernel_stat.h>
#include <linux/seq_file.h>
#include <linux/cpumask.h>
#include <asm/setup.h>
#include <asm/serial-regs.h>

unsigned long __mn10300_irq_enabled_epsw[NR_CPUS] __cacheline_aligned_in_smp = {
	[0 ... NR_CPUS - 1] = EPSW_IE | EPSW_IM_7
};
EXPORT_SYMBOL(__mn10300_irq_enabled_epsw);

#ifdef CONFIG_SMP
static char irq_affinity_online[NR_IRQS] = {
	[0 ... NR_IRQS - 1] = 0
};

#define NR_IRQ_WORDS	((NR_IRQS + 31) / 32)
static unsigned long irq_affinity_request[NR_IRQ_WORDS] = {
	[0 ... NR_IRQ_WORDS - 1] = 0
};
#endif  /* CONFIG_SMP */

atomic_t irq_err_count;

/*
 * MN10300 interrupt controller operations
 */
static void mn10300_cpupic_ack(struct irq_data *d)
{
	unsigned int irq = d->irq;
	unsigned long flags;
	u16 tmp;

	flags = arch_local_cli_save();
	GxICR_u8(irq) = GxICR_DETECT;
	tmp = GxICR(irq);
	arch_local_irq_restore(flags);
}

static void __mask_and_set_icr(unsigned int irq,
			       unsigned int mask, unsigned int set)
{
	unsigned long flags;
	u16 tmp;

	flags = arch_local_cli_save();
	tmp = GxICR(irq);
	GxICR(irq) = (tmp & mask) | set;
	tmp = GxICR(irq);
	arch_local_irq_restore(flags);
}

static void mn10300_cpupic_mask(struct irq_data *d)
{
	__mask_and_set_icr(d->irq, GxICR_LEVEL, 0);
}

static void mn10300_cpupic_mask_ack(struct irq_data *d)
{
	unsigned int irq = d->irq;
#ifdef CONFIG_SMP
	unsigned long flags;
	u16 tmp;

	flags = arch_local_cli_save();

	if (!test_and_clear_bit(irq, irq_affinity_request)) {
		tmp = GxICR(irq);
		GxICR(irq) = (tmp & GxICR_LEVEL) | GxICR_DETECT;
		tmp = GxICR(irq);
	} else {
		u16 tmp2;
		tmp = GxICR(irq);
		GxICR(irq) = (tmp & GxICR_LEVEL);
		tmp2 = GxICR(irq);

		irq_affinity_online[irq] =
			cpumask_any_and(irq_data_get_affinity_mask(d),
					cpu_online_mask);
		CROSS_GxICR(irq, irq_affinity_online[irq]) =
			(tmp & (GxICR_LEVEL | GxICR_ENABLE)) | GxICR_DETECT;
		tmp = CROSS_GxICR(irq, irq_affinity_online[irq]);
	}

	arch_local_irq_restore(flags);
#else  /* CONFIG_SMP */
	__mask_and_set_icr(irq, GxICR_LEVEL, GxICR_DETECT);
#endif /* CONFIG_SMP */
}

static void mn10300_cpupic_unmask(struct irq_data *d)
{
	__mask_and_set_icr(d->irq, GxICR_LEVEL, GxICR_ENABLE);
}

static void mn10300_cpupic_unmask_clear(struct irq_data *d)
{
	unsigned int irq = d->irq;
	/* the MN10300 PIC latches its interrupt request bit, even after the
	 * device has ceased to assert its interrupt line and the interrupt
	 * channel has been disabled in the PIC, so for level-triggered
	 * interrupts we need to clear the request bit when we re-enable */
#ifdef CONFIG_SMP
	unsigned long flags;
	u16 tmp;

	flags = arch_local_cli_save();

	if (!test_and_clear_bit(irq, irq_affinity_request)) {
		tmp = GxICR(irq);
		GxICR(irq) = (tmp & GxICR_LEVEL) | GxICR_ENABLE | GxICR_DETECT;
		tmp = GxICR(irq);
	} else {
		tmp = GxICR(irq);

		irq_affinity_online[irq] = cpumask_any_and(irq_data_get_affinity_mask(d),
							   cpu_online_mask);
		CROSS_GxICR(irq, irq_affinity_online[irq]) = (tmp & GxICR_LEVEL) | GxICR_ENABLE | GxICR_DETECT;
		tmp = CROSS_GxICR(irq, irq_affinity_online[irq]);
	}

	arch_local_irq_restore(flags);
#else  /* CONFIG_SMP */
	__mask_and_set_icr(irq, GxICR_LEVEL, GxICR_ENABLE | GxICR_DETECT);
#endif /* CONFIG_SMP */
}

#ifdef CONFIG_SMP
static int
mn10300_cpupic_setaffinity(struct irq_data *d, const struct cpumask *mask,
			   bool force)
{
	unsigned long flags;

	flags = arch_local_cli_save();
	set_bit(d->irq, irq_affinity_request);
	arch_local_irq_restore(flags);
	return 0;
}
#endif /* CONFIG_SMP */

/*
 * MN10300 PIC level-triggered IRQ handling.
 *
 * The PIC has no 'ACK' function per se.  It is possible to clear individual
 * channel latches, but each latch relatches whether or not the channel is
 * masked, so we need to clear the latch when we unmask the channel.
 *
 * Also for this reason, we don't supply an ack() op (it's unused anyway if
 * mask_ack() is provided), and mask_ack() just masks.
 */
static struct irq_chip mn10300_cpu_pic_level = {
	.name			= "cpu_l",
	.irq_disable		= mn10300_cpupic_mask,
	.irq_enable		= mn10300_cpupic_unmask_clear,
	.irq_ack		= NULL,
	.irq_mask		= mn10300_cpupic_mask,
	.irq_mask_ack		= mn10300_cpupic_mask,
	.irq_unmask		= mn10300_cpupic_unmask_clear,
#ifdef CONFIG_SMP
	.irq_set_affinity	= mn10300_cpupic_setaffinity,
#endif
};

/*
 * MN10300 PIC edge-triggered IRQ handling.
 *
 * We use the latch clearing function of the PIC as the 'ACK' function.
 */
static struct irq_chip mn10300_cpu_pic_edge = {
	.name			= "cpu_e",
	.irq_disable		= mn10300_cpupic_mask,
	.irq_enable		= mn10300_cpupic_unmask,
	.irq_ack		= mn10300_cpupic_ack,
	.irq_mask		= mn10300_cpupic_mask,
	.irq_mask_ack		= mn10300_cpupic_mask_ack,
	.irq_unmask		= mn10300_cpupic_unmask,
#ifdef CONFIG_SMP
	.irq_set_affinity	= mn10300_cpupic_setaffinity,
#endif
};

/*
 * 'what should we do if we get a hw irq event on an illegal vector'.
 * each architecture has to answer this themselves.
 */
void ack_bad_irq(int irq)
{
	printk(KERN_WARNING "unexpected IRQ trap at vector %02x\n", irq);
}

/*
 * change the level at which an IRQ executes
 * - must not be called whilst interrupts are being processed!
 */
void set_intr_level(int irq, u16 level)
{
	BUG_ON(in_interrupt());

	__mask_and_set_icr(irq, GxICR_ENABLE, level);
}

/*
 * mark an interrupt to be ACK'd after interrupt handlers have been run rather
 * than before
 */
void mn10300_set_lateack_irq_type(int irq)
{
	irq_set_chip_and_handler(irq, &mn10300_cpu_pic_level,
				 handle_level_irq);
}

/*
 * initialise the interrupt system
 */
void __init init_IRQ(void)
{
	int irq;

	for (irq = 0; irq < NR_IRQS; irq++)
		if (irq_get_chip(irq) == &no_irq_chip)
			/* due to the PIC latching interrupt requests, even
			 * when the IRQ is disabled, IRQ_PENDING is superfluous
			 * and we can use handle_level_irq() for edge-triggered
			 * interrupts */
			irq_set_chip_and_handler(irq, &mn10300_cpu_pic_edge,
						 handle_level_irq);

	unit_init_IRQ();
}

/*
 * handle normal device IRQs
 */
asmlinkage void do_IRQ(void)
{
	unsigned long sp, epsw, irq_disabled_epsw, old_irq_enabled_epsw;
	unsigned int cpu_id = smp_processor_id();
	int irq;

	sp = current_stack_pointer();
	BUG_ON(sp - (sp & ~(THREAD_SIZE - 1)) < STACK_WARN);

	/* make sure local_irq_enable() doesn't muck up the interrupt priority
	 * setting in EPSW */
	old_irq_enabled_epsw = __mn10300_irq_enabled_epsw[cpu_id];
	local_save_flags(epsw);
	__mn10300_irq_enabled_epsw[cpu_id] = EPSW_IE | (EPSW_IM & epsw);
	irq_disabled_epsw = EPSW_IE | MN10300_CLI_LEVEL;

#ifdef CONFIG_MN10300_WD_TIMER
	__IRQ_STAT(cpu_id, __irq_count)++;
#endif

	irq_enter();

	for (;;) {
		/* ask the interrupt controller for the next IRQ to process
		 * - the result we get depends on EPSW.IM
		 */
		irq = IAGR & IAGR_GN;
		if (!irq)
			break;

		local_irq_restore(irq_disabled_epsw);

		generic_handle_irq(irq >> 2);

		/* restore IRQ controls for IAGR access */
		local_irq_restore(epsw);
	}

	__mn10300_irq_enabled_epsw[cpu_id] = old_irq_enabled_epsw;

	irq_exit();
}

/*
 * Display interrupt management information through /proc/interrupts
 */
int arch_show_interrupts(struct seq_file *p, int prec)
{
#ifdef CONFIG_MN10300_WD_TIMER
	int j;

	seq_printf(p, "%*s: ", prec, "NMI");
	for (j = 0; j < NR_CPUS; j++)
		if (cpu_online(j))
			seq_printf(p, "%10u ", nmi_count(j));
	seq_putc(p, '\n');
#endif

	seq_printf(p, "%*s: ", prec, "ERR");
	seq_printf(p, "%10u\n", atomic_read(&irq_err_count));
	return 0;
}

#ifdef CONFIG_HOTPLUG_CPU
void migrate_irqs(void)
{
	int irq;
	unsigned int self, new;
	unsigned long flags;

	self = smp_processor_id();
	for (irq = 0; irq < NR_IRQS; irq++) {
		struct irq_data *data = irq_get_irq_data(irq);
		struct cpumask *mask = irq_data_get_affinity_mask(data);

		if (irqd_is_per_cpu(data))
			continue;

		if (cpumask_test_cpu(self, mask) &&
		    !cpumask_intersects(&irq_affinity[irq], cpu_online_mask)) {
			int cpu_id;
			cpu_id = cpumask_first(cpu_online_mask);
			cpumask_set_cpu(cpu_id, mask);
		}
		/* We need to operate irq_affinity_online atomically. */
		arch_local_cli_save(flags);
		if (irq_affinity_online[irq] == self) {
			u16 x, tmp;

			x = GxICR(irq);
			GxICR(irq) = x & GxICR_LEVEL;
			tmp = GxICR(irq);

			new = cpumask_any_and(mask, cpu_online_mask);
			irq_affinity_online[irq] = new;

			CROSS_GxICR(irq, new) =
				(x & GxICR_LEVEL) | GxICR_DETECT;
			tmp = CROSS_GxICR(irq, new);

			x &= GxICR_LEVEL | GxICR_ENABLE;
			if (GxICR(irq) & GxICR_REQUEST)
				x |= GxICR_REQUEST | GxICR_DETECT;
			CROSS_GxICR(irq, new) = x;
			tmp = CROSS_GxICR(irq, new);
		}
		arch_local_irq_restore(flags);
	}
}
#endif /* CONFIG_HOTPLUG_CPU */