ataints.c

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/*
 * 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 <[e-mail]>:
 *  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 <[e-mail]>:
 *  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 <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"						   \
SYMBOL_NAME_STR(atari_slow_irq_) #n "_handler:\t"			   \
"	addql	#1,"SYMBOL_NAME_STR(irq_stat)"+8\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	"SYMBOL_NAME_STR(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))	   \
);									   \
}

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"
SYMBOL_NAME_STR(atari_fast_irq_handler) ":
	orw 	#0x700,%%sr		/* disable all interrupts */
"SYMBOL_NAME_STR(atari_prio_irq_handler) ":\t
	addql	#1,"SYMBOL_NAME_STR(irq_stat)"+8\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	"SYMBOL_NAME_STR(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	"SYMBOL_NAME_STR(ret_from_interrupt)
	 : : "i" (&kstat.irqs[0]), "n" (PT_OFF_FORMATVEC)
);
}

/* 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"
SYMBOL_NAME_STR(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
 *