/*
 * arch/m68k/atari/ataints.c -- Atari Linux interrupt handling code
 *
 * 5/2/94 Roman Hodek:
 *  Added support for TT interrupts; setup for TT SCU (may someone has
 *  twiddled there and we won't get the right interrupts :-()
 *
 *  Major change: The device-independent code in m68k/ints.c didn't know
 *  about non-autovec ints yet. It hardcoded the number of possible ints to
 *  7 (IRQ1...IRQ7). But the Atari has lots of non-autovec ints! I made the
 *  number of possible ints a constant defined in interrupt.h, which is
 *  47 for the Atari. So we can call request_irq() for all Atari interrupts
 *  just the normal way. Additionally, all vectors >= 48 are initialized to
 *  call trap() instead of inthandler(). This must be changed here, too.
 *
 * 1995-07-16 Lars Brinkhoff <f93labr@dd.chalmers.se>:
 *  Corrected a bug in atari_add_isr() which rejected all SCC
 *  interrupt sources if there were no TT MFP!
 *
 * 12/13/95: New interface functions atari_level_triggered_int() and
 *  atari_register_vme_int() as support for level triggered VME interrupts.
 *
 * 02/12/96: (Roman)
 *  Total rewrite of Atari interrupt handling, for new scheme see comments
 *  below.
 *
 * 1996-09-03 lars brinkhoff <f93labr@dd.chalmers.se>:
 *  Added new function atari_unregister_vme_int(), and
 *  modified atari_register_vme_int() as well as IS_VALID_INTNO()
 *  to work with it.
 *
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file COPYING in the main directory of this archive
 * for more details.
 *
 */

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/ptrace.h>
#include <linux/kernel_stat.h>
#include <linux/init.h>
#include <linux/seq_file.h>

#include <asm/system.h>
#include <asm/traps.h>

#include <asm/atarihw.h>
#include <asm/atariints.h>
#include <asm/atari_stdma.h>
#include <asm/irq.h>
#include <asm/entry.h>


/*
 * Atari interrupt handling scheme:
 * --------------------------------
 * 
 * All interrupt source have an internal number (defined in
 * <asm/atariints.h>): Autovector interrupts are 1..7, then follow ST-MFP,
 * TT-MFP, SCC, and finally VME interrupts. Vector numbers for the latter can
 * be allocated by atari_register_vme_int().
 *
 * Each interrupt can be of three types:
 * 
 *  - SLOW: The handler runs with all interrupts enabled, except the one it
 *    was called by (to avoid reentering). This should be the usual method.
 *    But it is currently possible only for MFP ints, since only the MFP
 *    offers an easy way to mask interrupts.
 *
 *  - FAST: The handler runs with all interrupts disabled. This should be used
 *    only for really fast handlers, that just do actions immediately
 *    necessary, and let the rest do a bottom half or task queue.
 *
 *  - PRIORITIZED: The handler can be interrupted by higher-level ints
 *    (greater IPL, no MFP priorities!). This is the method of choice for ints
 *    which should be slow, but are not from a MFP.
 *
 * The feature of more than one handler for one int source is still there, but
 * only applicable if all handers are of the same type. To not slow down
 * processing of ints with only one handler by the chaining feature, the list
 * calling function atari_call_irq_list() is only plugged in at the time the
 * second handler is registered.
 *
 * Implementation notes: For fast-as-possible int handling, there are separate
 * entry points for each type (slow/fast/prio). The assembler handler calls
 * the irq directly in the usual case, no C wrapper is involved. In case of
 * multiple handlers, atari_call_irq_list() is registered as handler and calls
 * in turn the real irq's. To ease access from assembler level to the irq
 * function pointer and accompanying data, these two are stored in a separate
 * array, irq_handler[]. The rest of data (type, name) are put into a second
 * array, irq_param, that is accessed from C only. For each slow interrupt (32
 * in all) there are separate handler functions, which makes it possible to
 * hard-code the MFP register address and value, are necessary to mask the
 * int. If there'd be only one generic function, lots of calculations would be
 * needed to determine MFP register and int mask from the vector number :-(
 *
 * Furthermore, slow ints may not lower the IPL below its previous value
 * (before the int happened). This is needed so that an int of class PRIO, on
 * that this int may be stacked, cannot be reentered. This feature is
 * implemented as follows: If the stack frame format is 1 (throwaway), the int
 * is not stacked, and the IPL is anded with 0xfbff, resulting in a new level
 * 2, which still blocks the HSYNC, but no interrupts of interest. If the
 * frame format is 0, the int is nested, and the old IPL value can be found in
 * the sr copy in the frame.
 */


#define	NUM_INT_SOURCES	(8 + NUM_ATARI_SOURCES)

typedef void (*asm_irq_handler)(void);

struct irqhandler {
	void	(*handler)(int, void *, struct pt_regs *);
	void	*dev_id;
};

struct irqparam {
	unsigned long	flags;
	const char	*devname;
};

/*
 * Array with irq's and their parameter data. This array is accessed from low
 * level assembler code, so an element size of 8 allows usage of index scaling
 * addressing mode.
 */
static struct irqhandler irq_handler[NUM_INT_SOURCES];

/*
 * This array hold the rest of parameters of int handlers: type
 * (slow,fast,prio) and the name of the handler. These values are only
 * accessed from C
 */
static struct irqparam irq_param[NUM_INT_SOURCES];

/*
 * Bitmap for free interrupt vector numbers
 * (new vectors starting from 0x70 can be allocated by
 * atari_register_vme_int())
 */
static int free_vme_vec_bitmap = 0;

/* check for valid int number (complex, sigh...) */
#define	IS_VALID_INTNO(n)											\
	((n) > 0 &&														\
	 /* autovec and ST-MFP ok anyway */								\
	 (((n) < TTMFP_SOURCE_BASE) ||									\
	  /* TT-MFP ok if present */									\
	  ((n) >= TTMFP_SOURCE_BASE && (n) < SCC_SOURCE_BASE &&			\
	   ATARIHW_PRESENT(TT_MFP)) ||									\
	  /* SCC ok if present and number even */						\
	  ((n) >= SCC_SOURCE_BASE && (n) < VME_SOURCE_BASE &&			\
	   !((n) & 1) && ATARIHW_PRESENT(SCC)) ||						\
	  /* greater numbers ok if they are registered VME vectors */		\
	  ((n) >= VME_SOURCE_BASE && (n) < VME_SOURCE_BASE + VME_MAX_SOURCES && \
		  free_vme_vec_bitmap & (1 << ((n) - VME_SOURCE_BASE)))))


/*
 * Here start the assembler entry points for interrupts
 */

#define IRQ_NAME(nr) atari_slow_irq_##nr##_handler(void)

#define	BUILD_SLOW_IRQ(n)						   \
asmlinkage void IRQ_NAME(n);						   \
/* Dummy function to allow asm with operands.  */			   \
void atari_slow_irq_##n##_dummy (void) {				   \
__asm__ (__ALIGN_STR "\n"						   \
"atari_slow_irq_" #n "_handler:\t"					   \
"	addql	#1,%5\n"		/* local_irq_count++ */		   \
	SAVE_ALL_INT "\n"						   \
	GET_CURRENT(%%d0) "\n"						   \
"	andb	#~(1<<(%c3&7)),%a4:w\n"	/* mask this interrupt */	   \
	/* get old IPL from stack frame */				   \
"	bfextu	%%sp@(%c2){#5,#3},%%d0\n"				   \
"	movew	%%sr,%%d1\n"						   \
"	bfins	%%d0,%%d1{#21,#3}\n"					   \
"	movew	%%d1,%%sr\n"		/* set IPL = previous value */	   \
"	addql	#1,%a0\n"						   \
"	lea	%a1,%%a0\n"						   \
"	pea 	%%sp@\n"		/* push addr of frame */	   \
"	movel	%%a0@(4),%%sp@-\n"	/* push handler data */		   \
"	pea 	(%c3+8)\n"		/* push int number */		   \
"	movel	%%a0@,%%a0\n"						   \
"	jbsr	%%a0@\n"		/* call the handler */		   \
"	addql	#8,%%sp\n"						   \
"	addql	#4,%%sp\n"						   \
"	orw	#0x0600,%%sr\n"						   \
"	andw	#0xfeff,%%sr\n"		/* set IPL = 6 again */		   \
"	orb 	#(1<<(%c3&7)),%a4:w\n"	/* now unmask the int again */	   \
"	jbra	ret_from_interrupt\n"					   \
	 : : "i" (&kstat.irqs[0][n+8]), "i" (&irq_handler[n+8]),	   \
	     "n" (PT_OFF_SR), "n" (n),					   \
	     "i" (n & 8 ? (n & 16 ? &tt_mfp.int_mk_a : &mfp.int_mk_a)	   \
		        : (n & 16 ? &tt_mfp.int_mk_b : &mfp.int_mk_b)),	   \
	     "m" (local_irq_count(0))					   \
);									   \
	for (;;);			/* fake noreturn */		   \
}

BUILD_SLOW_IRQ(0);
BUILD_SLOW_IRQ(1);
BUILD_SLOW_IRQ(2);
BUILD_SLOW_IRQ(3);
BUILD_SLOW_IRQ(4);
BUILD_SLOW_IRQ(5);
BUILD_SLOW_IRQ(6);
BUILD_SLOW_IRQ(7);
BUILD_SLOW_IRQ(8);
BUILD_SLOW_IRQ(9);
BUILD_SLOW_IRQ(10);
BUILD_SLOW_IRQ(11);
BUILD_SLOW_IRQ(12);
BUILD_SLOW_IRQ(13);
BUILD_SLOW_IRQ(14);
BUILD_SLOW_IRQ(15);
BUILD_SLOW_IRQ(16);
BUILD_SLOW_IRQ(17);
BUILD_SLOW_IRQ(18);
BUILD_SLOW_IRQ(19);
BUILD_SLOW_IRQ(20);
BUILD_SLOW_IRQ(21);
BUILD_SLOW_IRQ(22);
BUILD_SLOW_IRQ(23);
BUILD_SLOW_IRQ(24);
BUILD_SLOW_IRQ(25);
BUILD_SLOW_IRQ(26);
BUILD_SLOW_IRQ(27);
BUILD_SLOW_IRQ(28);
BUILD_SLOW_IRQ(29);
BUILD_SLOW_IRQ(30);
BUILD_SLOW_IRQ(31);

asm_irq_handler slow_handlers[32] = {
	atari_slow_irq_0_handler,
	atari_slow_irq_1_handler,
	atari_slow_irq_2_handler,
	atari_slow_irq_3_handler,
	atari_slow_irq_4_handler,
	atari_slow_irq_5_handler,
	atari_slow_irq_6_handler,
	atari_slow_irq_7_handler,
	atari_slow_irq_8_handler,
	atari_slow_irq_9_handler,
	atari_slow_irq_10_handler,
	atari_slow_irq_11_handler,
	atari_slow_irq_12_handler,
	atari_slow_irq_13_handler,
	atari_slow_irq_14_handler,
	atari_slow_irq_15_handler,
	atari_slow_irq_16_handler,
	atari_slow_irq_17_handler,
	atari_slow_irq_18_handler,
	atari_slow_irq_19_handler,
	atari_slow_irq_20_handler,
	atari_slow_irq_21_handler,
	atari_slow_irq_22_handler,
	atari_slow_irq_23_handler,
	atari_slow_irq_24_handler,
	atari_slow_irq_25_handler,
	atari_slow_irq_26_handler,
	atari_slow_irq_27_handler,
	atari_slow_irq_28_handler,
	atari_slow_irq_29_handler,
	atari_slow_irq_30_handler,
	atari_slow_irq_31_handler
};

asmlinkage void atari_fast_irq_handler( void );
asmlinkage void atari_prio_irq_handler( void );

/* Dummy function to allow asm with operands.  */
void atari_fast_prio_irq_dummy (void) {
__asm__ (__ALIGN_STR "\n"
"atari_fast_irq_handler:
	orw 	#0x700,%%sr		/* disable all interrupts */
atari_prio_irq_handler:\t
	addql	#1,%2\n"		/* local_irq_count++ */
	SAVE_ALL_INT "\n"
	GET_CURRENT(%%d0) "
	/* get vector number from stack frame and convert to source */
	bfextu	%%sp@(%c1){#4,#10},%%d0
	subw	#(0x40-8),%%d0
	jpl 	1f
	addw	#(0x40-8-0x18),%%d0
1:	lea	%a0,%%a0
	addql	#1,%%a0@(%%d0:l:4)
	lea	irq_handler,%%a0
	lea	%%a0@(%%d0:l:8),%%a0
	pea 	%%sp@			/* push frame address */
	movel	%%a0@(4),%%sp@-		/* push handler data */
	movel	%%d0,%%sp@-		/* push int number */
	movel	%%a0@,%%a0
	jsr	%%a0@			/* and call the handler */
	addql	#8,%%sp
	addql	#4,%%sp
	jbra	ret_from_interrupt"
	 : : "i" (&kstat.irqs[0]), "n" (PT_OFF_FORMATVEC),
	     "m" (local_irq_count(0))
);
	for (;;);
}

/* GK:
 * HBL IRQ handler for Falcon. Nobody needs it :-)
 * ++andreas: raise ipl to disable further HBLANK interrupts.
 */
asmlinkage void falcon_hblhandler(void);
asm(".text\n"
__ALIGN_STR "\n"
"falcon_hblhandler:
	orw	#0x200,%sp@	/* set saved ipl to 2 */
	rte");

/* Defined in entry.S; only increments 'num_spurious' */
asmlinkage void bad_interrupt(void);

extern void atari_microwire_cmd( int cmd );

extern int atari_SCC_reset_done;

/*
 * void atari_init_IRQ (void)
 *
 * Parameters:	None
 *
 * Returns:	Nothing
 *
 * This function should be called during kernel startup to initialize
 * the atari IRQ handling routines.
 */

void __init atari_init_IRQ(void)
{
	int i;

	/* initialize the vector table */
	for (i = 0; i < NUM_INT_SOURCES; ++i) {
		vectors[IRQ_SOURCE_TO_VECTOR(i)] = bad_interrupt;
	}

	/* Initialize the MFP(s) */

#ifdef ATARI_USE_SOFTWARE_EOI
	mfp.vec_adr  = 0x48;	/* Software EOI-Mode */
#else
	mfp.vec_adr  = 0x40;	/* Automatic EOI-Mode */
#endif
	mfp.int_en_a = 0x00;	/* turn off MFP-Ints */
	mfp.int_en_b = 0x00;
	mfp.int_mk_a = 0xff;	/* no Masking */
	mfp.int_mk_b = 0xff;

	if (ATARIHW_PRESENT(TT_MFP)) {
#ifdef ATARI_USE_SOFTWARE_EOI
		tt_mfp.vec_adr  = 0x58;		/* Software EOI-Mode */
#else
		tt_mfp.vec_adr  = 0x50;		/* Automatic EOI-Mode */
#endif
		tt_mfp.int_en_a = 0x00;		/* turn off MFP-Ints */
		tt_mfp.int_en_b = 0x00;
		tt_mfp.int_mk_a = 0xff;		/* no Masking */
		tt_mfp.int_mk_b = 0xff;
	}

	if (ATARIHW_PRESENT(SCC) && !atari_SCC_reset_done) {
		scc.cha_a_ctrl = 9;
		MFPDELAY();
		scc.cha_a_ctrl = (char) 0xc0; /* hardware reset */
	}

	if (ATARIHW_PRESENT(SCU)) {
		/* init the SCU if present */
		tt_scu.sys_mask = 0x10;		/* enable VBL (for the cursor) and
									 * disable HSYNC interrupts (who
									 * needs them?)  MFP and SCC are
									 * enabled in VME mask
									 */
		tt_scu.vme_mask = 0x60;		/* enable MFP and SCC ints */
	}
	else {
		/* If no SCU and no Hades, the HSYNC interrupt needs to be
		 * disabled this way. (Else _inthandler in kernel/sys_call.S
		 * gets overruns)
		 */

		if (!MACH_IS_HADES)
			vectors[VEC_INT2] = falcon_hblhandler;
	}

	if (ATARIHW_PRESENT(PCM_8BIT) && ATARIHW_PRESENT(MICROWIRE)) {
		/* Initialize the LM1992 Sound Controller to enable
		   the PSG sound.  This is misplaced here, it should
		   be in an atasound_init(), that doesn't exist yet. */
		atari_microwire_cmd(MW_LM1992_PSG_HIGH);
	}
	
	stdma_init();

	/* Initialize the PSG: all sounds off, both ports output */
	sound_ym.rd_data_reg_sel = 7;
	sound_ym.wd_data = 0xff;
}


static void atari_call_irq_list( int irq, void *dev_id, struct pt_regs *fp )
{
	irq_node_t *node;

	for (node = (irq_node_t *)dev_id; node; node = node->next)
		node->handler(irq, node->dev_id, fp);
}


/*
 * atari_request_irq : add an interrupt service routine for a particular
 *                     machine specific interrupt source.
 *                     If the addition was successful, it returns 0.
 */

int atari_request_irq(unsigned int irq, void (*handler)(int, void *, struct pt_regs *),
                      unsigned long flags, const char *devname, void *dev_id)
{
	int vector;
	unsigned long oflags = flags;

	/*
	 * The following is a hack to make some PCI card drivers work,
	 * which set the SA_SHIRQ flag.
	 */

	flags &= ~SA_SHIRQ;

	if (flags == SA_INTERRUPT) {
		printk ("%s: SA_INTERRUPT changed to IRQ_TYPE_SLOW for %s\n",
			__FUNCTION__, devname);
		flags = IRQ_TYPE_SLOW;
	}
	if (flags < IRQ_TYPE_SLOW || flags > IRQ_TYPE_PRIO) {
		printk ("%s: Bad irq type 0x%lx <0x%lx> requested from %s\n",
		        __FUNCTION__, flags, oflags, devname);
		return -EINVAL;
	}
	if (!IS_VALID_INTNO(irq)) {
		printk ("%s: Unknown irq %d requested from %s\n",
		        __FUNCTION__, irq, devname);
		return -ENXIO;
	}
	vector = IRQ_SOURCE_TO_VECTOR(irq);

	/*
	 * Check type/source combination: slow ints are (currently)
	 * only possible for MFP-interrupts.
	 */
	if (flags == IRQ_TYPE_SLOW &&
		(irq < STMFP_SOURCE_BASE || irq >= SCC_SOURCE_BASE)) {
		printk ("%s: Slow irq requested for non-MFP source %d from %s\n",
		        __FUNCTION__, irq, devname);
		return -EINVAL;
	}
		
	if (vectors[vector] == bad_interrupt) {
		/* int has no handler yet */
		irq_handler[irq].handler = handler;
		irq_handler[irq].dev_id  = dev_id;
		irq_param[irq].flags   = flags;
		irq_param[irq].devname = devname;
		vectors[vector] =
			(flags == IRQ_TYPE_SLOW) ? slow_handlers[irq-STMFP_SOURCE_BASE] :
			(flags == IRQ_TYPE_FAST) ? atari_fast_irq_handler :
			                          atari_prio_irq_handler;
		/* If MFP int, also enable and umask it */
		atari_turnon_irq(irq);
		atari_enable_irq(irq);

		return 0;
	}
	else if (irq_param[irq].flags == flags) {
		/* old handler is of same type -> handlers can be chained */
		irq_node_t *node;
		unsigned long flags;

		save_flags(flags);
		cli();

		if (irq_handler[irq].handler != atari_call_irq_list) {
			/* Only one handler yet, make a node for this first one */
			if (!(node = new_irq_node()))
				return -ENOMEM;
			node->handler = irq_handler[irq].handler;
			node->dev_id  = irq_handler[irq].dev_id;
			node->devname = irq_param[irq].devname;
			node->next = NULL;

			irq_handler[irq].handler = atari_call_irq_list;
			irq_handler[irq].dev_id  = node;
			irq_param[irq].devname   = "chained";
		}

		if (!(node = new_irq_node()))
			return -ENOMEM;
		node->handler = handler;
		node->dev_id  = dev_id;
		node->devname = devname;
		/* new handlers are put in front of the queue */
		node->next = irq_handler[irq].dev_id;
		irq_handler[irq].dev_id = node;

		restore_flags(flags);
		return 0;
	} else {
		printk ("%s: Irq %d allocated by other type int (call from %s)\n",
		        __FUNCTION__, irq, devname);
		return -EBUSY;
	}
}

void atari_free_irq(unsigned int irq, void *dev_id)
{
	unsigned long flags;
	int vector;
	irq_node_t **list, *node;

	if (!IS_VALID_INTNO(irq)) {
		printk("%s: Unknown irq %d\n", __FUNCTION__, irq);
		return;
	}

	vector = IRQ_SOURCE_TO_VECTOR(irq);
	if (vectors[vector] == bad_interrupt)
		goto not_found;

	save_flags(flags);
	cli();

	if (irq_handler[irq].handler != atari_call_irq_list) {
		/* It's the only handler for the interrupt */
		if (irq_handler[irq].dev_id != dev_id) {
			restore_flags(flags);
			goto not_found;
		}
		irq_handler[irq].handler = NULL;
		irq_handler[irq].dev_id  = NULL;
		irq_param[irq].devname   = NULL;
		vectors[vector] = bad_interrupt;
		/* If MFP int, also disable it */
		atari_disable_irq(irq);
		atari_turnoff_irq(irq);

		restore_flags(flags);
		return;
	}

	/* The interrupt is chained, find the irq on the list */
	for(list = (irq_node_t **)&irq_handler[irq].dev_id; *list; list = &(*list)->next) {
		if ((*list)->dev_id == dev_id) break;
	}
	if (!*list) {
		restore_flags(flags);
		goto not_found;
	}

	(*list)->handler = NULL; /* Mark it as free for reallocation */
	*list = (*list)->next;

	/* If there's now only one handler, unchain the interrupt, i.e. plug in
	 * the handler directly again and omit atari_call_irq_list */
	node = (irq_node_t *)irq_handler[irq].dev_id;
	if (node && !node->next) {
		irq_handler[irq].handler = node->handler;
		irq_handler[irq].dev_id  = node->dev_id;
		irq_param[irq].devname   = node->devname;
		node->handler = NULL; /* Mark it as free for reallocation */
	}

	restore_flags(flags);
	return;

not_found:
	printk("%s: tried to remove invalid irq\n", __FUNCTION__);
	return;
}


/*
 * atari_register_vme_int() returns the number of a free interrupt vector for
 * hardware with a programmable int vector (probably a VME board).
 */

unsigned long atari_register_vme_int(void)
{
	int i;

	for(i = 0; i < 32; i++)
		if((free_vme_vec_bitmap & (1 << i)) == 0)
			break;
	
	if(i == 16)
		return 0;

	free_vme_vec_bitmap |= 1 << i;
	return (VME_SOURCE_BASE + i);
}


void atari_unregister_vme_int(unsigned long irq)
{
	if(irq >= VME_SOURCE_BASE && irq < VME_SOURCE_BASE + VME_MAX_SOURCES) {
		irq -= VME_SOURCE_BASE;
		free_vme_vec_bitmap &= ~(1 << irq);
	}
}


int show_atari_interrupts(struct seq_file *p, void *v)
{
	int i;

	for (i = 0; i < NUM_INT_SOURCES; ++i) {
		if (vectors[IRQ_SOURCE_TO_VECTOR(i)] == bad_interrupt)
			continue;
		if (i < STMFP_SOURCE_BASE)
			seq_printf(p, "auto %2d: %10u ",
				       i, kstat.irqs[0][i]);
		else
			seq_printf(p, "vec $%02x: %10u ",
				       IRQ_SOURCE_TO_VECTOR(i),
				       kstat.irqs[0][i]);

		if (irq_handler[i].handler != atari_call_irq_list) {
			seq_printf(p, "%s\n", irq_param[i].devname);
		}
		else {
			irq_node_t *n;
			for( n = (irq_node_t *)irq_handler[i].dev_id; n; n = n->next ) {
				seq_printf(p, "%s\n", n->devname);
				if (n->next)
					seq_puts(p, "                    " );
			}
		}
	}
	if (num_spurious)
		seq_printf(p, "spurio.: %10u\n", num_spurious);
	
	return 0;
}


