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irq.c

/*
 * Copyright (C) 2000, 2001, 2002, 2003 Broadcom Corporation
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/linkage.h>
#include <linux/interrupt.h>
#include <linux/spinlock.h>
#include <linux/smp.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/kernel_stat.h>

#include <asm/errno.h>
#include <asm/signal.h>
#include <asm/system.h>
#include <asm/time.h>
#include <asm/io.h>

#include <asm/sibyte/sb1250_regs.h>
#include <asm/sibyte/sb1250_int.h>
#include <asm/sibyte/sb1250_uart.h>
#include <asm/sibyte/sb1250_scd.h>
#include <asm/sibyte/sb1250.h>

/*
 * These are the routines that handle all the low level interrupt stuff.
 * Actions handled here are: initialization of the interrupt map, requesting of
 * interrupt lines by handlers, dispatching if interrupts to handlers, probing
 * for interrupt lines
 */


static void end_sb1250_irq(unsigned int irq);
static void enable_sb1250_irq(unsigned int irq);
static void disable_sb1250_irq(unsigned int irq);
static void ack_sb1250_irq(unsigned int irq);
#ifdef CONFIG_SMP
static void sb1250_set_affinity(unsigned int irq, cpumask_t mask);
#endif

#ifdef CONFIG_SIBYTE_HAS_LDT
extern unsigned long ldt_eoi_space;
#endif

static struct irq_chip sb1250_irq_type = {
      .name = "SB1250-IMR",
      .ack = ack_sb1250_irq,
      .mask = disable_sb1250_irq,
      .mask_ack = ack_sb1250_irq,
      .unmask = enable_sb1250_irq,
      .end = end_sb1250_irq,
#ifdef CONFIG_SMP
      .set_affinity = sb1250_set_affinity
#endif
};

/* Store the CPU id (not the logical number) */
int sb1250_irq_owner[SB1250_NR_IRQS];

DEFINE_SPINLOCK(sb1250_imr_lock);

void sb1250_mask_irq(int cpu, int irq)
{
      unsigned long flags;
      u64 cur_ints;

      spin_lock_irqsave(&sb1250_imr_lock, flags);
      cur_ints = ____raw_readq(IOADDR(A_IMR_MAPPER(cpu) +
                              R_IMR_INTERRUPT_MASK));
      cur_ints |= (((u64) 1) << irq);
      ____raw_writeq(cur_ints, IOADDR(A_IMR_MAPPER(cpu) +
                              R_IMR_INTERRUPT_MASK));
      spin_unlock_irqrestore(&sb1250_imr_lock, flags);
}

void sb1250_unmask_irq(int cpu, int irq)
{
      unsigned long flags;
      u64 cur_ints;

      spin_lock_irqsave(&sb1250_imr_lock, flags);
      cur_ints = ____raw_readq(IOADDR(A_IMR_MAPPER(cpu) +
                              R_IMR_INTERRUPT_MASK));
      cur_ints &= ~(((u64) 1) << irq);
      ____raw_writeq(cur_ints, IOADDR(A_IMR_MAPPER(cpu) +
                              R_IMR_INTERRUPT_MASK));
      spin_unlock_irqrestore(&sb1250_imr_lock, flags);
}

#ifdef CONFIG_SMP
static void sb1250_set_affinity(unsigned int irq, cpumask_t mask)
{
      int i = 0, old_cpu, cpu, int_on;
      u64 cur_ints;
      struct irq_desc *desc = irq_desc + irq;
      unsigned long flags;

      i = first_cpu(mask);

      if (cpus_weight(mask) > 1) {
            printk("attempted to set irq affinity for irq %d to multiple CPUs\n", irq);
            return;
      }

      /* Convert logical CPU to physical CPU */
      cpu = cpu_logical_map(i);

      /* Protect against other affinity changers and IMR manipulation */
      spin_lock_irqsave(&desc->lock, flags);
      spin_lock(&sb1250_imr_lock);

      /* Swizzle each CPU's IMR (but leave the IP selection alone) */
      old_cpu = sb1250_irq_owner[irq];
      cur_ints = ____raw_readq(IOADDR(A_IMR_MAPPER(old_cpu) +
                              R_IMR_INTERRUPT_MASK));
      int_on = !(cur_ints & (((u64) 1) << irq));
      if (int_on) {
            /* If it was on, mask it */
            cur_ints |= (((u64) 1) << irq);
            ____raw_writeq(cur_ints, IOADDR(A_IMR_MAPPER(old_cpu) +
                              R_IMR_INTERRUPT_MASK));
      }
      sb1250_irq_owner[irq] = cpu;
      if (int_on) {
            /* unmask for the new CPU */
            cur_ints = ____raw_readq(IOADDR(A_IMR_MAPPER(cpu) +
                              R_IMR_INTERRUPT_MASK));
            cur_ints &= ~(((u64) 1) << irq);
            ____raw_writeq(cur_ints, IOADDR(A_IMR_MAPPER(cpu) +
                              R_IMR_INTERRUPT_MASK));
      }
      spin_unlock(&sb1250_imr_lock);
      spin_unlock_irqrestore(&desc->lock, flags);
}
#endif

/*****************************************************************************/

static void disable_sb1250_irq(unsigned int irq)
{
      sb1250_mask_irq(sb1250_irq_owner[irq], irq);
}

static void enable_sb1250_irq(unsigned int irq)
{
      sb1250_unmask_irq(sb1250_irq_owner[irq], irq);
}


static void ack_sb1250_irq(unsigned int irq)
{
#ifdef CONFIG_SIBYTE_HAS_LDT
      u64 pending;

      /*
       * If the interrupt was an HT interrupt, now is the time to
       * clear it.  NOTE: we assume the HT bridge was set up to
       * deliver the interrupts to all CPUs (which makes affinity
       * changing easier for us)
       */
      pending = __raw_readq(IOADDR(A_IMR_REGISTER(sb1250_irq_owner[irq],
                                        R_IMR_LDT_INTERRUPT)));
      pending &= ((u64)1 << (irq));
      if (pending) {
            int i;
            for (i=0; i<NR_CPUS; i++) {
                  int cpu;
#ifdef CONFIG_SMP
                  cpu = cpu_logical_map(i);
#else
                  cpu = i;
#endif
                  /*
                   * Clear for all CPUs so an affinity switch
                   * doesn't find an old status
                   */
                  __raw_writeq(pending,
                             IOADDR(A_IMR_REGISTER(cpu,
                                    R_IMR_LDT_INTERRUPT_CLR)));
            }

            /*
             * Generate EOI.  For Pass 1 parts, EOI is a nop.  For
             * Pass 2, the LDT world may be edge-triggered, but
             * this EOI shouldn't hurt.  If they are
             * level-sensitive, the EOI is required.
             */
            *(uint32_t *)(ldt_eoi_space+(irq<<16)+(7<<2)) = 0;
      }
#endif
      sb1250_mask_irq(sb1250_irq_owner[irq], irq);
}


static void end_sb1250_irq(unsigned int irq)
{
      if (!(irq_desc[irq].status & (IRQ_DISABLED | IRQ_INPROGRESS))) {
            sb1250_unmask_irq(sb1250_irq_owner[irq], irq);
      }
}


void __init init_sb1250_irqs(void)
{
      int i;

      for (i = 0; i < SB1250_NR_IRQS; i++) {
            set_irq_chip(i, &sb1250_irq_type);
            sb1250_irq_owner[i] = 0;
      }
}


/*
 *  arch_init_irq is called early in the boot sequence from init/main.c via
 *  init_IRQ.  It is responsible for setting up the interrupt mapper and
 *  installing the handler that will be responsible for dispatching interrupts
 *  to the "right" place.
 */
/*
 * For now, map all interrupts to IP[2].  We could save
 * some cycles by parceling out system interrupts to different
 * IP lines, but keep it simple for bringup.  We'll also direct
 * all interrupts to a single CPU; we should probably route
 * PCI and LDT to one cpu and everything else to the other
 * to balance the load a bit.
 *
 * On the second cpu, everything is set to IP5, which is
 * ignored, EXCEPT the mailbox interrupt.  That one is
 * set to IP[2] so it is handled.  This is needed so we
 * can do cross-cpu function calls, as requred by SMP
 */

#define IMR_IP2_VAL     K_INT_MAP_I0
#define IMR_IP3_VAL     K_INT_MAP_I1
#define IMR_IP4_VAL     K_INT_MAP_I2
#define IMR_IP5_VAL     K_INT_MAP_I3
#define IMR_IP6_VAL     K_INT_MAP_I4

void __init arch_init_irq(void)
{

      unsigned int i;
      u64 tmp;
      unsigned int imask = STATUSF_IP4 | STATUSF_IP3 | STATUSF_IP2 |
            STATUSF_IP1 | STATUSF_IP0;

      /* Default everything to IP2 */
      for (i = 0; i < SB1250_NR_IRQS; i++) {    /* was I0 */
            __raw_writeq(IMR_IP2_VAL,
                       IOADDR(A_IMR_REGISTER(0,
                                       R_IMR_INTERRUPT_MAP_BASE) +
                            (i << 3)));
            __raw_writeq(IMR_IP2_VAL,
                       IOADDR(A_IMR_REGISTER(1,
                                       R_IMR_INTERRUPT_MAP_BASE) +
                            (i << 3)));
      }

      init_sb1250_irqs();

      /*
       * Map the high 16 bits of the mailbox registers to IP[3], for
       * inter-cpu messages
       */
      /* Was I1 */
      __raw_writeq(IMR_IP3_VAL,
                 IOADDR(A_IMR_REGISTER(0, R_IMR_INTERRUPT_MAP_BASE) +
                      (K_INT_MBOX_0 << 3)));
      __raw_writeq(IMR_IP3_VAL,
                 IOADDR(A_IMR_REGISTER(1, R_IMR_INTERRUPT_MAP_BASE) +
                      (K_INT_MBOX_0 << 3)));

      /* Clear the mailboxes.  The firmware may leave them dirty */
      __raw_writeq(0xffffffffffffffffULL,
                 IOADDR(A_IMR_REGISTER(0, R_IMR_MAILBOX_CLR_CPU)));
      __raw_writeq(0xffffffffffffffffULL,
                 IOADDR(A_IMR_REGISTER(1, R_IMR_MAILBOX_CLR_CPU)));

      /* Mask everything except the mailbox registers for both cpus */
      tmp = ~((u64) 0) ^ (((u64) 1) << K_INT_MBOX_0);
      __raw_writeq(tmp, IOADDR(A_IMR_REGISTER(0, R_IMR_INTERRUPT_MASK)));
      __raw_writeq(tmp, IOADDR(A_IMR_REGISTER(1, R_IMR_INTERRUPT_MASK)));

      /*
       * Note that the timer interrupts are also mapped, but this is
       * done in sb1250_time_init().  Also, the profiling driver
       * does its own management of IP7.
       */

      /* Enable necessary IPs, disable the rest */
      change_c0_status(ST0_IM, imask);
}

extern void sb1250_mailbox_interrupt(void);

static inline void dispatch_ip2(void)
{
      unsigned int cpu = smp_processor_id();
      unsigned long long mask;

      /*
       * Default...we've hit an IP[2] interrupt, which means we've got to
       * check the 1250 interrupt registers to figure out what to do.  Need
       * to detect which CPU we're on, now that smp_affinity is supported.
       */
      mask = __raw_readq(IOADDR(A_IMR_REGISTER(cpu,
                          R_IMR_INTERRUPT_STATUS_BASE)));
      if (mask)
            do_IRQ(fls64(mask) - 1);
}

asmlinkage void plat_irq_dispatch(void)
{
      unsigned int cpu = smp_processor_id();
      unsigned int pending;

      /*
       * What a pain. We have to be really careful saving the upper 32 bits
       * of any * register across function calls if we don't want them
       * trashed--since were running in -o32, the calling routing never saves
       * the full 64 bits of a register across a function call.  Being the
       * interrupt handler, we're guaranteed that interrupts are disabled
       * during this code so we don't have to worry about random interrupts
       * blasting the high 32 bits.
       */

      pending = read_c0_cause() & read_c0_status() & ST0_IM;

      if (pending & CAUSEF_IP7) /* CPU performance counter interrupt */
            do_IRQ(MIPS_CPU_IRQ_BASE + 7);
      else if (pending & CAUSEF_IP4)
            do_IRQ(K_INT_TIMER_0 + cpu);  /* sb1250_timer_interrupt() */

#ifdef CONFIG_SMP
      else if (pending & CAUSEF_IP3)
            sb1250_mailbox_interrupt();
#endif

      else if (pending & CAUSEF_IP2)
            dispatch_ip2();
      else
            spurious_interrupt();
}

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