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ataints.c

/*
 * 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/kernel_stat.h>
#include <linux/init.h>
#include <linux/seq_file.h>
#include <linux/module.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.
 */

#if 0

#define     NUM_INT_SOURCES   (8 + NUM_ATARI_SOURCES)

typedef void (*asm_irq_handler)(void);

struct irqhandler {
      irqreturn_t (*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];

/* 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"                             \
"     addl  %6,%5\n"    /* preempt_count() += HARDIRQ_OFFSET */      \
      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_cpu(0).irqs[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" (preempt_count()), "di" (HARDIRQ_OFFSET)              \
);                                                       \
      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] = {
      [0]   = atari_slow_irq_0_handler,
      [1]   = atari_slow_irq_1_handler,
      [2]   = atari_slow_irq_2_handler,
      [3]   = atari_slow_irq_3_handler,
      [4]   = atari_slow_irq_4_handler,
      [5]   = atari_slow_irq_5_handler,
      [6]   = atari_slow_irq_6_handler,
      [7]   = atari_slow_irq_7_handler,
      [8]   = atari_slow_irq_8_handler,
      [9]   = atari_slow_irq_9_handler,
      [10]  = atari_slow_irq_10_handler,
      [11]  = atari_slow_irq_11_handler,
      [12]  = atari_slow_irq_12_handler,
      [13]  = atari_slow_irq_13_handler,
      [14]  = atari_slow_irq_14_handler,
      [15]  = atari_slow_irq_15_handler,
      [16]  = atari_slow_irq_16_handler,
      [17]  = atari_slow_irq_17_handler,
      [18]  = atari_slow_irq_18_handler,
      [19]  = atari_slow_irq_19_handler,
      [20]  = atari_slow_irq_20_handler,
      [21]  = atari_slow_irq_21_handler,
      [22]  = atari_slow_irq_22_handler,
      [23]  = atari_slow_irq_23_handler,
      [24]  = atari_slow_irq_24_handler,
      [25]  = atari_slow_irq_25_handler,
      [26]  = atari_slow_irq_26_handler,
      [27]  = atari_slow_irq_27_handler,
      [28]  = atari_slow_irq_28_handler,
      [29]  = atari_slow_irq_29_handler,
      [30]  = atari_slow_irq_30_handler,
      [31]  = 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:\n\t"
      "orw  #0x700,%%sr\n"          /* disable all interrupts */
"atari_prio_irq_handler:\n\t"
      "addl %3,%2\n\t"        /* preempt_count() += HARDIRQ_OFFSET */
      SAVE_ALL_INT "\n\t"
      GET_CURRENT(%%d0) "\n\t"
      /* get vector number from stack frame and convert to source */
      "bfextu     %%sp@(%c1){#4,#10},%%d0\n\t"
      "subw #(0x40-8),%%d0\n\t"
      "jpl  1f\n\t"
      "addw #(0x40-8-0x18),%%d0\n"
    "1:\tlea      %a0,%%a0\n\t"
      "addql      #1,%%a0@(%%d0:l:4)\n\t"
      "lea  irq_handler,%%a0\n\t"
      "lea  %%a0@(%%d0:l:8),%%a0\n\t"
      "pea  %%sp@\n\t"        /* push frame address */
      "movel      %%a0@(4),%%sp@-\n\t"    /* push handler data */
      "movel      %%d0,%%sp@-\n\t"  /* push int number */
      "movel      %%a0@,%%a0\n\t"
      "jsr  %%a0@\n\t"        /* and call the handler */
      "addql      #8,%%sp\n\t"
      "addql      #4,%%sp\n\t"
      "jbra ret_from_interrupt"
       : : "i" (&kstat_cpu(0).irqs), "n" (PT_OFF_FORMATVEC),
           "m" (preempt_count()), "di" (HARDIRQ_OFFSET)
);
      for (;;);
}
#endif

/*
 * 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;

/* 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\t"
"falcon_hblhandler:\n\t"
      "orw  #0x200,%sp@\n\t"  /* set saved ipl to 2 */
      "rte");

extern void atari_microwire_cmd(int cmd);

extern int atari_SCC_reset_done;

static int atari_startup_irq(unsigned int irq)
{
      m68k_irq_startup(irq);
      atari_turnon_irq(irq);
      atari_enable_irq(irq);
      return 0;
}

static void atari_shutdown_irq(unsigned int irq)
{
      atari_disable_irq(irq);
      atari_turnoff_irq(irq);
      m68k_irq_shutdown(irq);

      if (irq == IRQ_AUTO_4)
          vectors[VEC_INT4] = falcon_hblhandler;
}

static struct irq_controller atari_irq_controller = {
      .name       = "atari",
      .lock       = __SPIN_LOCK_UNLOCKED(atari_irq_controller.lock),
      .startup    = atari_startup_irq,
      .shutdown   = atari_shutdown_irq,
      .enable           = atari_enable_irq,
      .disable    = atari_disable_irq,
};

/*
 * 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)
{
      m68k_setup_user_interrupt(VEC_USER, NUM_ATARI_SOURCES - IRQ_USER, NULL);
      m68k_setup_irq_controller(&atari_irq_controller, 1, NUM_ATARI_SOURCES - 1);

      /* 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;
                  vectors[VEC_INT4] = 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;
}


/*
 * 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;
}
EXPORT_SYMBOL(atari_register_vme_int);


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);
      }
}
EXPORT_SYMBOL(atari_unregister_vme_int);



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