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/*

 * Code to handle Baget/MIPS IRQs plus some generic interrupt stuff.

 *

 * Copyright (C) 1998 Vladimir Roganov & Gleb Raiko

 *      Code (mostly sleleton and comments) derived from DECstation IRQ

 *      handling.

 */

#include <linux/errno.h>

#include <linux/init.h>

#include <linux/kernel_stat.h>

#include <linux/signal.h>

#include <linux/sched.h>

#include <linux/types.h>

#include <linux/interrupt.h>

#include <linux/ioport.h>

#include <linux/timex.h>

#include <linux/slab.h>

#include <linux/random.h>

#include <linux/delay.h>

#include <asm/bitops.h>

#include <asm/bootinfo.h>

#include <asm/io.h>

#include <asm/irq.h>

#include <asm/mipsregs.h>

#include <asm/system.h>

#include <asm/baget/baget.h>

volatile unsigned long irq_err_count;

/*

 * This table is a correspondence between IRQ numbers and CPU PILs

 */

static int irq_to_pil_map[BAGET_IRQ_NR] = {

        7/*fixme: dma_err -1*/,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1,-1, /* 0x00 - 0x0f */

        -1,-1,-1,-1, 3,-1,-1,-1, 2, 2, 2,-1, 3,-1,-1,3/*fixme: lance*/, /* 0x10 - 0x1f */

        -1,-1,-1,-1,-1,-1, 5,-1,-1,-1,-1,-1, 7,-1,-1,-1, /* 0x20 - 0x2f */

        -1, 3, 2/*fixme systimer:3*/, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3  /* 0x30 - 0x3f */

};

static inline int irq_to_pil(int irq_nr)

{

        int pil = -1;

        if (irq_nr >= BAGET_IRQ_NR)

                baget_printk("irq_to_pil: too large irq_nr = 0x%x\n", irq_nr);

        else {

                pil = irq_to_pil_map[irq_nr];

                if (pil == -1)

                        baget_printk("irq_to_pil: unknown irq = 0x%x\n", irq_nr);

        }

        return pil;

}

/* Function for careful CP0 interrupt mask access */

static inline void modify_cp0_intmask(unsigned clr_mask, unsigned set_mask)

{

        unsigned long status = read_c0_status();

        status &= ~((clr_mask & 0xFF) << 8);

        status |=   (set_mask & 0xFF) << 8;

        write_c0_status(status);

}

/*

 *  These two functions may be used for unconditional IRQ

 *  masking via their PIL protection.

 */

static inline void mask_irq(unsigned int irq_nr)

{

        modify_cp0_intmask(irq_to_pil(irq_nr), 0);

}

static inline void unmask_irq(unsigned int irq_nr)

{

        modify_cp0_intmask(0, irq_to_pil(irq_nr));

}

/*

 * The following section is introduced for masking/unasking IRQ

 * only while no more IRQs uses same CPU PIL.

 *

 * These functions are used in request_irq, free_irq, but it looks

 * they cannot change something: CP0_STATUS is private for any

 * process, and their action is invisible for system.

 */

static volatile unsigned int pil_in_use[BAGET_PIL_NR] = { 0, };

void mask_irq_count(int irq_nr)

{

        unsigned long flags;

        int pil = irq_to_pil(irq_nr);

        save_and_cli(flags);

        if (!--pil_in_use[pil])

                mask_irq(irq_nr);

        restore_flags(flags);

}

void unmask_irq_count(int irq_nr)

{

        unsigned long flags;

        int pil = irq_to_pil(irq_nr);

        save_and_cli(flags);

        if (!pil_in_use[pil]++)

                unmask_irq(irq_nr);

        restore_flags(flags);

}

/*

 * Two functions below are exported versions of mask/unmask IRQ

 */

void disable_irq(unsigned int irq_nr)

{

        unsigned long flags;

        save_and_cli(flags);

        mask_irq(irq_nr);

        restore_flags(flags);

}

void enable_irq(unsigned int irq_nr)

{

        unsigned long flags;

        save_and_cli(flags);

        unmask_irq(irq_nr);

        restore_flags(flags);

}

/*

 * Pointers to the low-level handlers: first the general ones, then the

 * fast ones, then the bad ones.

 */

static struct irqaction *irq_action[BAGET_IRQ_NR] = { NULL, };

int get_irq_list(char *buf)

{

        int i, len = 0;

        struct irqaction * action;

        for (i = 0 ; i < BAGET_IRQ_NR ; i++) {

                action = irq_action[i];

                if (!action)

                        continue;

                len += sprintf(buf+len, "%2d: %8d %c %s",

                        i, kstat.irqs[0][i],

                        (action->flags & SA_INTERRUPT) ? '+' : ' ',

                        action->name);

                for (action=action->next; action; action = action->next) {

                        len += sprintf(buf+len, ",%s %s",

                                (action->flags & SA_INTERRUPT) ? " +" : "",

                                action->name);

                }

                len += sprintf(buf+len, "\n");

        }

        return len;

}

/*

 * do_IRQ handles IRQ's that have been installed without the

 * SA_INTERRUPT flag: it uses the full signal-handling return

 * and runs with other interrupts enabled. All relatively slow

 * IRQ's should use this format: notably the keyboard/timer

 * routines.

 */

static void do_IRQ(int irq, struct pt_regs * regs)

{

        struct irqaction *action;

        int do_random, cpu;

        cpu = smp_processor_id();

        irq_enter(cpu, irq);

        kstat.irqs[cpu][irq]++;

        mask_irq(irq);

        action = *(irq + irq_action);

        if (action) {

                if (!(action->flags & SA_INTERRUPT))

                        __sti();

                action = *(irq + irq_action);

                do_random = 0;

                do {

                        do_random |= action->flags;

                        action->handler(irq, action->dev_id, regs);

                        action = action->next;

                } while (action);

                if (do_random & SA_SAMPLE_RANDOM)

                        add_interrupt_randomness(irq);

                __cli();

        } else {

                printk("do_IRQ: Unregistered IRQ (0x%X) occurred\n", irq);

        }

        unmask_irq(irq);

        irq_exit(cpu, irq);

        /* unmasking and bottom half handling is done magically for us. */

}

/*

 *  What to do in case of 'no VIC register available' for current interrupt

 */

static void vic_reg_error(unsigned long address, unsigned char active_pils)

{

        printk("\nNo VIC register found: reg=%08lx active_pils=%02x\n"

               "Current interrupt mask from CP0_CAUSE: %02x\n",

               address, 0xff & active_pils,

               0xff & (read_c0_cause()>>8));

        { int i; for (i=0; i<10000; i++) udelay(1000); }

}

static char baget_fpu_irq = BAGET_FPU_IRQ;

#define BAGET_INT_FPU {(unsigned long)&baget_fpu_irq, 1}

/*

 *  Main interrupt handler: interrupt demultiplexer

 */

asmlinkage void baget_interrupt(struct pt_regs *regs)

{

        static struct baget_int_reg int_reg[BAGET_PIL_NR] = {

                BAGET_INT_NONE, BAGET_INT_NONE, BAGET_INT0_ACK, BAGET_INT1_ACK,

                BAGET_INT_NONE, BAGET_INT_FPU,  BAGET_INT_NONE, BAGET_INT5_ACK

        };

        unsigned char active_pils;

        while ((active_pils = read_c0_cause()>>8)) {

                int pil;

                struct baget_int_reg* reg;

                for (pil = 0; pil < BAGET_PIL_NR; pil++) {

                        if (!(active_pils & (1<<pil))) continue;

                        reg = &int_reg[pil];

                        if (reg->address) {

                                extern int try_read(unsigned long,int);

                                int irq  = try_read(reg->address, reg->size);

                                if (irq != -1)

                                      do_IRQ(BAGET_IRQ_MASK(irq), regs);

                                else

                                      vic_reg_error(reg->address, active_pils);

                        } else {

                                printk("baget_interrupt: unknown interrupt "

                                       "(pil = %d)\n", pil);

                        }

                }

        }

}

/*

 * Idea is to put all interrupts

 * in a single table and differenciate them just by number.

 */

int setup_baget_irq(int irq, struct irqaction * new)

{

        int shared = 0;

        struct irqaction *old, **p;

        unsigned long flags;

        p = irq_action + irq;

        if ((old = *p) != NULL) {

                /* Can't share interrupts unless both agree to */

                if (!(old->flags & new->flags & SA_SHIRQ))

                        return -EBUSY;

                /* Can't share interrupts unless both are same type */

                if ((old->flags ^ new->flags) & SA_INTERRUPT)

                        return -EBUSY;

                /* add new interrupt at end of irq queue */

                do {

                        p = &old->next;

                        old = *p;

                } while (old);

                shared = 1;

        }

        if (new->flags & SA_SAMPLE_RANDOM)

                rand_initialize_irq(irq);

        save_and_cli(flags);

        *p = new;

        restore_flags(flags);

        if (!shared) {

                unmask_irq_count(irq);

        }

        return 0;

}

int request_irq(unsigned int irq,

                void (*handler)(int, void *, struct pt_regs *),

                unsigned long irqflags,

                const char * devname,

                void *dev_id)

{

        int retval;

        struct irqaction * action;

        if (irq >= BAGET_IRQ_NR)

                return -EINVAL;

        if (!handler)

                return -EINVAL;

        if (irq_to_pil_map[irq] < 0)

                return -EINVAL;

        action = (struct irqaction *)

                        kmalloc(sizeof(struct irqaction), GFP_KERNEL);

        if (!action)

                return -ENOMEM;

        action->handler = handler;

        action->flags = irqflags;

        action->mask = 0;

        action->name = devname;

        action->next = NULL;

        action->dev_id = dev_id;

        retval = setup_baget_irq(irq, action);

        if (retval)

                kfree(action);

        return retval;

}

void free_irq(unsigned int irq, void *dev_id)

{

        struct irqaction * action, **p;

        unsigned long flags;

        if (irq >= BAGET_IRQ_NR)

                printk("Trying to free IRQ%d\n",irq);

        for (p = irq + irq_action; (action = *p) != NULL; p = &action->next) {

                if (action->dev_id != dev_id)

                        continue;

                /* Found it - now free it */

                save_and_cli(flags);

                *p = action->next;

                if (!irq[irq_action])

                        unmask_irq_count(irq);

                restore_flags(flags);

                kfree(action);

                return;

        }

        printk("Trying to free free IRQ%d\n",irq);

}

unsigned long probe_irq_on (void)

{

        /* TODO */

        return 0;

}

int probe_irq_off (unsigned long irqs)

{

        /* TODO */

        return 0;

}

static void write_err_interrupt(int irq, void *dev_id, struct pt_regs * regs)

{

        *(volatile char*) BAGET_WRERR_ACK = 0;

}

static struct irqaction irq0  =

{ write_err_interrupt, SA_INTERRUPT, 0, "bus write error", NULL, NULL};

void __init init_IRQ(void)

{

        irq_setup();

        /* Enable access to VIC interrupt registers */

        vac_outw(0xacef | 0x8200, VAC_PIO_FUNC);

        /* Enable interrupts for pils 2 and 3 (lines 0 and 1) */

        modify_cp0_intmask(0, (1<<2)|(1<<3));

        if (setup_baget_irq(0, &irq0) < 0)

                printk("init_IRQ: unable to register write_err irq\n");

}