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malta-smtc.c

/*
 * Malta Platform-specific hooks for SMP operation
 */
#include <linux/irq.h>
#include <linux/init.h>

#include <asm/mipsregs.h>
#include <asm/mipsmtregs.h>
#include <asm/smtc.h>
#include <asm/smtc_ipi.h>

/* VPE/SMP Prototype implements platform interfaces directly */

/*
 * Cause the specified action to be performed on a targeted "CPU"
 */

static void msmtc_send_ipi_single(int cpu, unsigned int action)
{
      /* "CPU" may be TC of same VPE, VPE of same CPU, or different CPU */
      smtc_send_ipi(cpu, LINUX_SMP_IPI, action);
}

static void msmtc_send_ipi_mask(const struct cpumask *mask, unsigned int action)
{
      unsigned int i;

      for_each_cpu(i, mask)
            msmtc_send_ipi_single(i, action);
}

/*
 * Post-config but pre-boot cleanup entry point
 */
static void __cpuinit msmtc_init_secondary(void)
{
      void smtc_init_secondary(void);
      int myvpe;

      /* Don't enable Malta I/O interrupts (IP2) for secondary VPEs */
      myvpe = read_c0_tcbind() & TCBIND_CURVPE;
      if (myvpe != 0) {
            /* Ideally, this should be done only once per VPE, but... */
            clear_c0_status(ST0_IM);
            set_c0_status((0x100 << cp0_compare_irq)
                        | (0x100 << MIPS_CPU_IPI_IRQ));
            if (cp0_perfcount_irq >= 0)
                  set_c0_status(0x100 << cp0_perfcount_irq);
      }

      smtc_init_secondary();
}

/*
 * Platform "CPU" startup hook
 */
static void __cpuinit msmtc_boot_secondary(int cpu, struct task_struct *idle)
{
      smtc_boot_secondary(cpu, idle);
}

/*
 * SMP initialization finalization entry point
 */
static void __cpuinit msmtc_smp_finish(void)
{
      smtc_smp_finish();
}

/*
 * Hook for after all CPUs are online
 */

static void msmtc_cpus_done(void)
{
}

/*
 * Platform SMP pre-initialization
 *
 * As noted above, we can assume a single CPU for now
 * but it may be multithreaded.
 */

static void __init msmtc_smp_setup(void)
{
      /*
       * we won't get the definitive value until
       * we've run smtc_prepare_cpus later, but
       * we would appear to need an upper bound now.
       */
      smp_num_siblings = smtc_build_cpu_map(0);
}

static void __init msmtc_prepare_cpus(unsigned int max_cpus)
{
      smtc_prepare_cpus(max_cpus);
}

struct plat_smp_ops msmtc_smp_ops = {
      .send_ipi_single  = msmtc_send_ipi_single,
      .send_ipi_mask          = msmtc_send_ipi_mask,
      .init_secondary         = msmtc_init_secondary,
      .smp_finish       = msmtc_smp_finish,
      .cpus_done        = msmtc_cpus_done,
      .boot_secondary         = msmtc_boot_secondary,
      .smp_setup        = msmtc_smp_setup,
      .prepare_cpus           = msmtc_prepare_cpus,
};

#ifdef CONFIG_MIPS_MT_SMTC_IRQAFF
/*
 * IRQ affinity hook
 */


int plat_set_irq_affinity(unsigned int irq, const struct cpumask *affinity)
{
      cpumask_t tmask;
      int cpu = 0;
      void smtc_set_irq_affinity(unsigned int irq, cpumask_t aff);

      /*
       * On the legacy Malta development board, all I/O interrupts
       * are routed through the 8259 and combined in a single signal
       * to the CPU daughterboard, and on the CoreFPGA2/3 34K models,
       * that signal is brought to IP2 of both VPEs. To avoid racing
       * concurrent interrupt service events, IP2 is enabled only on
       * one VPE, by convention VPE0.  So long as no bits are ever
       * cleared in the affinity mask, there will never be any
       * interrupt forwarding.  But as soon as a program or operator
       * sets affinity for one of the related IRQs, we need to make
       * sure that we don't ever try to forward across the VPE boundry,
       * at least not until we engineer a system where the interrupt
       * _ack() or _end() function can somehow know that it corresponds
       * to an interrupt taken on another VPE, and perform the appropriate
       * restoration of Status.IM state using MFTR/MTTR instead of the
       * normal local behavior. We also ensure that no attempt will
       * be made to forward to an offline "CPU".
       */

      cpumask_copy(&tmask, affinity);
      for_each_cpu(cpu, affinity) {
            if ((cpu_data[cpu].vpe_id != 0) || !cpu_online(cpu))
                  cpu_clear(cpu, tmask);
      }
      cpumask_copy(irq_desc[irq].affinity, &tmask);

      if (cpus_empty(tmask))
            /*
             * We could restore a default mask here, but the
             * runtime code can anyway deal with the null set
             */
            printk(KERN_WARNING
                  "IRQ affinity leaves no legal CPU for IRQ %d\n", irq);

      /* Do any generic SMTC IRQ affinity setup */
      smtc_set_irq_affinity(irq, tmask);

      return 0;
}
#endif /* CONFIG_MIPS_MT_SMTC_IRQAFF */

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