/*
 *  arch/ppc/kernel/irq.c
 *
 *  Derived from arch/i386/kernel/irq.c
 *    Copyright (C) 1992 Linus Torvalds
 *  Adapted from arch/i386 by Gary Thomas
 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
 *  Updated and modified by Cort Dougan (cort@cs.nmt.edu)
 *  Adapted for Power Macintosh by Paul Mackerras
 *    Copyright (C) 1996 Paul Mackerras (paulus@cs.anu.edu.au)
 *
 * This file contains the code used by various IRQ handling routines:
 * asking for different IRQ's should be done through these routines
 * instead of just grabbing them. Thus setups with different IRQ numbers
 * shouldn't result in any weird surprises, and installing new handlers
 * should be easier.
 */


#include <linux/ptrace.h>
#include <linux/errno.h>
#include <linux/kernel_stat.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/ioport.h>
#include <linux/interrupt.h>
#include <linux/timex.h>
#include <linux/config.h>
#include <linux/init.h>
#include <linux/malloc.h>
#include <linux/openpic.h>
#include <linux/pci.h>
#include <linux/bios32.h>
#include <linux/openpic.h>

#include <asm/hydra.h>
#include <asm/system.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/bitops.h>
#include <asm/gg2.h>

#undef SHOW_IRQ

unsigned lost_interrupts = 0;
unsigned int local_irq_count[NR_CPUS];
static struct irqaction irq_action[NR_IRQS];
static int spurious_interrupts = 0;
static unsigned int cached_irq_mask = 0xffffffff;
static void no_action(int cpl, void *dev_id, struct pt_regs *regs) { }
spinlock_t irq_controller_lock;
#ifdef __SMP__
atomic_t __ppc_bh_counter = ATOMIC_INIT(0);
#else
int __ppc_bh_counter = 0;
#endif

#define cached_21	(((char *)(&cached_irq_mask))[3])
#define cached_A1	(((char *)(&cached_irq_mask))[2])

/*
 * These are set to the appropriate functions by init_IRQ()
 */
void (*mask_and_ack_irq)(int irq_nr);
void (*mask_irq)(unsigned int irq_nr);
void (*unmask_irq)(unsigned int irq_nr);


/* prep */
#define PREP_IRQ_MASK	(((unsigned int)cached_A1)<<8) | (unsigned int)cached_21
extern unsigned long route_pci_interrupts(void);

/* pmac */
#define IRQ_FLAG	((unsigned *)0xf3000020)
#define IRQ_ENABLE	((unsigned *)0xf3000024)
#define IRQ_ACK		((unsigned *)0xf3000028)
#define IRQ_LEVEL	((unsigned *)0xf300002c)
#define KEYBOARD_IRQ	20	/* irq number for command-power interrupt */
#define PMAC_IRQ_MASK	(~ld_le32(IRQ_ENABLE))


void i8259_mask_and_ack_irq(int irq_nr)
{
	spin_lock(&irq_controller_lock);
	cached_irq_mask |= 1 << irq_nr;
	if (irq_nr > 7) {
		inb(0xA1);	/* DUMMY */
		outb(cached_A1,0xA1);
		outb(0x62,0x20);	/* Specific EOI to cascade */
		/*outb(0x20,0xA0);*/
		outb(0x60|(irq_nr-8), 0xA0); /* specific eoi */
	} else {
		inb(0x21);	/* DUMMY */
		outb(cached_21,0x21);
		/*outb(0x20,0x20);*/
		outb(0x60|irq_nr,0x20); /* specific eoi */
		  
	}
	spin_unlock(&irq_controller_lock);
}

void pmac_mask_and_ack_irq(int irq_nr)
{
	unsigned long bit = 1UL << irq_nr;

	spin_lock(&irq_controller_lock);
	cached_irq_mask |= bit;
	lost_interrupts &= ~bit;
	out_le32(IRQ_ACK, bit);
	out_le32(IRQ_ENABLE, ~cached_irq_mask);
	out_le32(IRQ_ACK, bit);
	spin_unlock(&irq_controller_lock);
}

void chrp_mask_and_ack_irq(int irq_nr)
{
	/* spinlocks are done by i8259_mask_and_ack() - Cort */
	if (is_8259_irq(irq_nr))
	    i8259_mask_and_ack_irq(irq_nr);
}


static void i8259_set_irq_mask(int irq_nr)
{
	if (irq_nr > 7) {
		outb(cached_A1,0xA1);
	} else {
		outb(cached_21,0x21);
	}
}

static void pmac_set_irq_mask(int irq_nr)
{
	unsigned long bit = 1UL << irq_nr;

	/* this could be being enabled or disabled - so use cached_irq_mask */
	out_le32(IRQ_ENABLE, ~cached_irq_mask /* enable all unmasked */ );
	/*
	 * Unfortunately, setting the bit in the enable register
	 * when the device interrupt is already on *doesn't* set
	 * the bit in the flag register or request another interrupt.
	 */
	if ((bit & ~cached_irq_mask)
	    && (ld_le32(IRQ_LEVEL) & bit) && !(ld_le32(IRQ_FLAG) & bit))
		lost_interrupts |= bit;
}

/*
 * These have to be protected by the spinlock
 * before being called.
 */
static void i8259_mask_irq(unsigned int irq_nr)
{
	cached_irq_mask |= 1 << irq_nr;
	i8259_set_irq_mask(irq_nr);
}

static void i8259_unmask_irq(unsigned int irq_nr)
{
	cached_irq_mask &= ~(1 << irq_nr);
	i8259_set_irq_mask(irq_nr);
}

static void pmac_mask_irq(unsigned int irq_nr)
{
	cached_irq_mask |= 1 << irq_nr;
	pmac_set_irq_mask(irq_nr);
}

static void pmac_unmask_irq(unsigned int irq_nr)
{
	cached_irq_mask &= ~(1 << irq_nr);
	pmac_set_irq_mask(irq_nr);
}

static void chrp_mask_irq(unsigned int irq_nr)
{
	if (is_8259_irq(irq_nr))
		i8259_mask_irq(irq_nr);
	else
		openpic_disable_irq(irq_to_openpic(irq_nr));
}

static void chrp_unmask_irq(unsigned int irq_nr)
{
	if (is_8259_irq(irq_nr))
		i8259_unmask_irq(irq_nr);
	else
		openpic_enable_irq(irq_to_openpic(irq_nr));
}

void disable_irq(unsigned int irq_nr)
{
	unsigned long flags;

	spin_lock_irqsave(&irq_controller_lock, flags);
	mask_irq(irq_nr);
	spin_unlock_irqrestore(&irq_controller_lock, flags);
	synchronize_irq();
}

void enable_irq(unsigned int irq_nr)
{
	unsigned long flags;

	spin_lock_irqsave(&irq_controller_lock, flags);
	unmask_irq(irq_nr);
	spin_unlock_irqrestore(&irq_controller_lock, flags);
}

int get_irq_list(char *buf)
{
	int i, len = 0;
	struct irqaction * action;

	for (i = 0 ; i < NR_IRQS ; i++) {
		action = irq_action + i;
		if (!action || !action->handler)
			continue;
		len += sprintf(buf+len, "%2d: %10u   %s",
			i, kstat.interrupts[i], action->name);
		for (action=action->next; action; action = action->next) {
			len += sprintf(buf+len, ", %s", action->name);
		}
		len += sprintf(buf+len, "\n");
	}
	len += sprintf(buf+len, "99: %10u   spurious or short\n",
		       spurious_interrupts);
	return len;
}


#ifdef __SMP__
/* Who has global_irq_lock. */
unsigned char global_irq_holder = NO_PROC_ID;

/* This protects IRQ's. */
spinlock_t global_irq_lock = SPIN_LOCK_UNLOCKED;
unsigned long previous_irqholder;

/* This protects BH software state (masks, things like that). */
spinlock_t global_bh_lock = SPIN_LOCK_UNLOCKED;

/* Global IRQ locking depth. */
atomic_t global_irq_count = ATOMIC_INIT(0);

#undef INIT_STUCK
#define INIT_STUCK 100000000

#undef STUCK
#define STUCK \
if (!--stuck) {printk("wait_on_irq CPU#%d stuck at %08lx, waiting for %08lx (local=%d, global=%d)\n", cpu, where, previous_irqholder, local_count, atomic_read(&global_irq_count)); stuck = INIT_STUCK; }

void wait_on_irq(int cpu, unsigned long where)
{
	int stuck = INIT_STUCK;
	int local_count = local_irq_count[cpu];

	/* Are we the only one in an interrupt context? */
	while (local_count != atomic_read(&global_irq_count)) {
		/*
		 * No such luck. Now we need to release the lock,
		 * _and_ release our interrupt context, because
		 * otherwise we'd have dead-locks and live-locks
		 * and other fun things.
		 */
		atomic_sub(local_count, &global_irq_count);
		spin_unlock(&global_irq_lock);

		/*
		 * Wait for everybody else to go away and release
		 * their things before trying to get the lock again.
		 */
		for (;;) {
			STUCK;
			if (atomic_read(&global_irq_count))
				continue;
			if (*((unsigned char *)&global_irq_lock))
				continue;
			if (spin_trylock(&global_irq_lock))
				break;
		}
		atomic_add(local_count, &global_irq_count);
	}
}

#define irq_active(cpu) \
	(global_irq_count != local_irq_count[cpu])

/*
 * This is called when we want to synchronize with
 * interrupts. We may for example tell a device to
 * stop sending interrupts: but to make sure there
 * are no interrupts that are executing on another
 * CPU we need to call this function.
 *
 * On UP this is a no-op.
 */
void synchronize_irq(void)
{
	int cpu = smp_processor_id();
	int local_count = local_irq_count[cpu];

	/* Do we need to wait? */
	if (local_count != atomic_read(&global_irq_count)) {
		/* The stupid way to do this */
		cli();
		sti();
	}
}

#undef INIT_STUCK
#define INIT_STUCK 10000000

#undef STUCK
#define STUCK \
if (!--stuck) {\
ll_printk("get_irqlock stuck at %08lx, waiting for %08lx\n", where, previous_irqholder); stuck = INIT_STUCK;}

void get_irqlock(int cpu, unsigned long where)
{
	int stuck = INIT_STUCK;
	if (!spin_trylock(&global_irq_lock)) {
		/* do we already hold the lock? */
		if ((unsigned char) cpu == global_irq_holder)
			return;
		/* Uhhuh.. Somebody else got it. Wait.. */
		do {
			do {
				STUCK;
				barrier();
			} while (*((unsigned char *)&global_irq_lock));
		} while (!spin_trylock(&global_irq_lock));
	}
	
	/*
	 * Ok, we got the lock bit.
	 * But that's actually just the easy part.. Now
	 * we need to make sure that nobody else is running
	 * in an interrupt context. 
	 */
	wait_on_irq(cpu, where);
	/*
	 * Finally.
	 */
	global_irq_holder = cpu;
	previous_irqholder = where;
}

void __global_cli(void)
{
	int cpu = smp_processor_id();
	unsigned long where;
	__asm__("mr %0,31" : "=r" (where)); /* get lr */
	__cli();
	get_irqlock(cpu, where);
}

void __global_sti(void)
{
	release_irqlock(smp_processor_id());
	__sti();
}

unsigned long __global_save_flags(void)
{
	return global_irq_holder == (unsigned char) smp_processor_id();
}

void __global_restore_flags(unsigned long flags)
{
	switch (flags) {
	case 0:
		release_irqlock(smp_processor_id());
		__sti();
		break;
	case 1:
		__global_cli();
		break;
	default:
		printk("global_restore_flags: %08lx (%08lx)\n",
			flags, (&flags)[-1]);
	}
}
#endif /* __SMP__ */


asmlinkage void do_IRQ(struct pt_regs *regs)
{
	int irq;
	unsigned long bits;
	struct irqaction *action;
	int cpu = smp_processor_id();
	int status;
	int openpic_eoi_done = 0;

#ifdef __SMP__
	if ( cpu != 0 )
		panic("cpu %d received interrupt", cpu);
#endif /* __SMP__ */		

	hardirq_enter(cpu);

	/*
	 * I'll put this ugly mess of code into a function
	 * such as get_pending_irq() or some such clear thing
	 * so we don't have a switch in the irq code and
	 * the chrp code is merged a bit with the prep.
	 * -- Cort
	 */
	switch ( _machine )
	{
	case _MACH_Pmac:
		bits = ld_le32(IRQ_FLAG) | lost_interrupts;
		for (irq = NR_IRQS - 1; irq >= 0; --irq)
			if (bits & (1U << irq))
				break;
		break;
	case _MACH_chrp:
		irq = openpic_irq(0);		
		if (irq == IRQ_8259_CASCADE)
		{
			/*
			 * This magic address generates a PCI IACK cycle.
			 * 
			 * This should go in the above mask/ack code soon. -- Cort
			 */
			irq = *(volatile unsigned char *)GG2_INT_ACK_SPECIAL;
			/*
			 * Acknowledge as soon as possible to allow i8259
			 * interrupt nesting
			 */
			openpic_eoi(0);
			openpic_eoi_done = 1;
		}
		else if (irq >= OPENPIC_VEC_TIMER)
		{
			/*
			 *  OpenPIC interrupts >64 will be used for other purposes
			 *  like interprocessor interrupts and hardware errors
			 */
			if (irq == OPENPIC_VEC_SPURIOUS) {
				/*
				 * Spurious interrupts should never be
				 * acknowledged
				 */
				spurious_interrupts++;
				openpic_eoi_done = 1;
			} else {
				/*
				 * Here we should process IPI timer
				 * for now the interrupt is dismissed.
				 */
			}
			goto out;
		}
		break;
	case _MACH_prep:
#if 1
		outb(0x0C, 0x20);
		irq = inb(0x20) & 7;
		if (irq == 2)
		{
retry_cascade:
			outb(0x0C, 0xA0);
			irq = inb(0xA0);
			/* if no intr left */
			if ( !(irq & 128 ) )
				goto out;
			irq = (irq&7) + 8;
		}
		bits = 1UL << irq;
#else
		/*
		 * get the isr from the intr controller since
		 * the bit in the irr has been cleared
		 */
		outb(0x0a, 0x20);
		bits = inb(0x20)&0xff;
		/* handle cascade */
		if ( bits & 4 )
		{
			bits &= ~4UL;
			outb(0x0a, 0xA0);
			bits |= inb(0xA0)<<8;
		}
		/* ignore masked irqs */
		bits &= ~cached_irq_mask;
#endif		
		break;
	}
	
	if (irq < 0) {
		printk("Bogus interrupt from PC = %lx\n", regs->nip);
		goto out;
	}

	mask_and_ack_irq(irq);

	status = 0;
	action = irq_action + irq;
	kstat.interrupts[irq]++;
	if (action->handler) {
		if (!(action->flags & SA_INTERRUPT))
			__sti();
		status |= action->flags;
		action->handler(irq, action->dev_id, regs);
		/*if (status & SA_SAMPLE_RANDOM)
			add_interrupt_randomness(irq);*/
		__cli(); /* in case the handler turned them on */
		spin_lock(&irq_controller_lock);
		unmask_irq(irq);
		spin_unlock(&irq_controller_lock);
	} else {
		if ( irq == 7 ) /* i8259 gives us irq 7 on 'short' intrs */
			spurious_interrupts++;
		disable_irq( irq );
	}
	
	/* make sure we don't miss any cascade intrs due to eoi-ing irq 2 */
	if ( is_prep && (irq > 7) )
		goto retry_cascade;
	/* do_bottom_half is called if necessary from int_return in head.S */
out:
	if (_machine == _MACH_chrp && !openpic_eoi_done)
		openpic_eoi(0);
	hardirq_exit(cpu);
}

int request_irq(unsigned int irq, void (*handler)(int, void *, struct pt_regs *),
	unsigned long irqflags, const char * devname, void *dev_id)
{
	struct irqaction * action;
	unsigned long flags;

#ifdef SHOW_IRQ
	printk("request_irq(): irq %d handler %08x name %s dev_id %04x\n",
	       irq,handler,devname,dev_id);
#endif /* SHOW_IRQ */

	if (irq >= NR_IRQS)
		return -EINVAL;
	action = irq + irq_action;
	if (action->handler)
		return -EBUSY;
	if (!handler)
		return -EINVAL;
	save_flags(flags);
	cli();
	action->handler = handler;
	action->flags = irqflags;
	action->mask = 0;
	action->name = devname;
	action->dev_id = dev_id;
	enable_irq(irq);
	restore_flags(flags);
	return 0;
}

void free_irq(unsigned int irq, void *dev_id)
{
	struct irqaction * action = irq + irq_action;
	unsigned long flags;

#ifdef SHOW_IRQ
	printk("free_irq(): irq %d dev_id %04x\n", irq, dev_id);
#endif /* SHOW_IRQ */

	if (irq >= NR_IRQS) {
		printk("Trying to free IRQ%d\n",irq);
		return;
	}
	if (!action->handler) {
		printk("Trying to free free IRQ%d\n",irq);
		return;
	}
	disable_irq(irq);
	save_flags(flags);
	cli();
	action->handler = NULL;
	action->flags = 0;
	action->mask = 0;
	action->name = NULL;
	action->dev_id = NULL;
	restore_flags(flags);
}

unsigned long probe_irq_on (void)
{
	return 0;
}

int probe_irq_off (unsigned long irqs)
{
	return 0;
}

__initfunc(static void i8259_init(void))
{
	/* init master interrupt controller */
	outb(0x11, 0x20); /* Start init sequence */
	outb(0x00, 0x21); /* Vector base */
	outb(0x04, 0x21); /* edge tiggered, Cascade (slave) on IRQ2 */
	outb(0x01, 0x21); /* Select 8086 mode */
	outb(0xFF, 0x21); /* Mask all */
	
	/* init slave interrupt controller */
	outb(0x11, 0xA0); /* Start init sequence */
	outb(0x08, 0xA1); /* Vector base */
	outb(0x02, 0xA1); /* edge triggered, Cascade (slave) on IRQ2 */
	outb(0x01, 0xA1); /* Select 8086 mode */
	outb(0xFF, 0xA1); /* Mask all */
	outb(cached_A1, 0xA1);
	outb(cached_21, 0x21);
	if (request_irq(2, no_action, SA_INTERRUPT, "cascade", NULL) != 0)
		panic("Could not allocate cascade IRQ!");
	enable_irq(2);  /* Enable cascade interrupt */
}

__initfunc(void init_IRQ(void))
{
	extern void xmon_irq(int, void *, struct pt_regs *);

	switch (_machine)
	{
	case _MACH_Pmac:
		mask_and_ack_irq = pmac_mask_and_ack_irq;
		mask_irq = pmac_mask_irq;
		unmask_irq = pmac_unmask_irq;
		
		*IRQ_ENABLE = 0;
#ifdef CONFIG_XMON
		request_irq(KEYBOARD_IRQ, xmon_irq, 0, "NMI", 0);
#endif	/* CONFIG_XMON */
		break;
	case _MACH_chrp:
		mask_and_ack_irq = chrp_mask_and_ack_irq;
		mask_irq = chrp_mask_irq;
		unmask_irq = chrp_unmask_irq;
		ioremap(GG2_INT_ACK_SPECIAL, 1);
		openpic_init();
		i8259_init();
#ifdef CONFIG_XMON
		request_irq(openpic_to_irq(HYDRA_INT_ADB_NMI),
			    xmon_irq, 0, "NMI", 0);
#endif	/* CONFIG_XMON */
		break;
	case _MACH_prep:
		mask_and_ack_irq = i8259_mask_and_ack_irq;
		mask_irq = i8259_mask_irq;
		unmask_irq = i8259_unmask_irq;
		
		i8259_init();
		route_pci_interrupts();
		/*
		 * According to the Carolina spec from ibm irq's 0,1,2, and 8
		 * must be edge triggered.  Also, the pci intrs must be level
		 * triggered and _only_ isa intrs can be level sensitive
		 * which are 3-7,9-12,14-15. 13 is special - it can be level.
		 *
		 * power on default is 0's in both regs - all edge.
		 *
		 * These edge/level control regs allow edge/level status
		 * to be decided on a irq basis instead of on a PIC basis.
		 * It's still pretty ugly.
		 * - Cort
		 */
		{
			unsigned char irq_mode1 = 0, irq_mode2 = 0;
			irq_mode1 = 0; /* to get rid of compiler warnings */
			/*
			 * On Carolina, irq 15 and 13 must be level (scsi/ide/net).
			 */
			if ( _prep_type == _PREP_IBM )
				irq_mode2 |= 0xa0;
			/*
			 * Sound on the Powerstack reportedly needs to be edge triggered
			 */
			if ( _prep_type == _PREP_Motorola )
			{
				irq_mode2 &= ~0x04L;
				irq_mode2 = 0xca;
				outb( irq_mode1 , 0x4d0 );
				outb( irq_mode2 , 0x4d1 );
			}

		}
		break;
	}
}