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smp-cmp.c

/*
 *  This program is free software; you can distribute it and/or modify it
 *  under the terms of the GNU General Public License (Version 2) as
 *  published by the Free Software Foundation.
 *
 *  This program is distributed in the hope 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.
 *
 * Copyright (C) 2007 MIPS Technologies, Inc.
 *    Chris Dearman (chris@mips.com)
 */

#undef DEBUG

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/cpumask.h>
#include <linux/interrupt.h>
#include <linux/compiler.h>

#include <asm/atomic.h>
#include <asm/cacheflush.h>
#include <asm/cpu.h>
#include <asm/processor.h>
#include <asm/system.h>
#include <asm/hardirq.h>
#include <asm/mmu_context.h>
#include <asm/smp.h>
#include <asm/time.h>
#include <asm/mipsregs.h>
#include <asm/mipsmtregs.h>
#include <asm/mips_mt.h>

/*
 * Crude manipulation of the CPU masks to control which
 * which CPU's are brought online during initialisation
 *
 * Beware... this needs to be called after CPU discovery
 * but before CPU bringup
 */
static int __init allowcpus(char *str)
{
      cpumask_t cpu_allow_map;
      char buf[256];
      int len;

      cpus_clear(cpu_allow_map);
      if (cpulist_parse(str, cpu_allow_map) == 0) {
            cpu_set(0, cpu_allow_map);
            cpus_and(cpu_possible_map, cpu_possible_map, cpu_allow_map);
            len = cpulist_scnprintf(buf, sizeof(buf)-1, cpu_possible_map);
            buf[len] = '\0';
            pr_debug("Allowable CPUs: %s\n", buf);
            return 1;
      } else
            return 0;
}
__setup("allowcpus=", allowcpus);

static void ipi_call_function(unsigned int cpu)
{
      unsigned int action = 0;

      pr_debug("CPU%d: %s cpu %d status %08x\n",
             smp_processor_id(), __func__, cpu, read_c0_status());

      switch (cpu) {
      case 0:
            action = GIC_IPI_EXT_INTR_CALLFNC_VPE0;
            break;
      case 1:
            action = GIC_IPI_EXT_INTR_CALLFNC_VPE1;
            break;
      case 2:
            action = GIC_IPI_EXT_INTR_CALLFNC_VPE2;
            break;
      case 3:
            action = GIC_IPI_EXT_INTR_CALLFNC_VPE3;
            break;
      }
      gic_send_ipi(action);
}


static void ipi_resched(unsigned int cpu)
{
      unsigned int action = 0;

      pr_debug("CPU%d: %s cpu %d status %08x\n",
             smp_processor_id(), __func__, cpu, read_c0_status());

      switch (cpu) {
      case 0:
            action = GIC_IPI_EXT_INTR_RESCHED_VPE0;
            break;
      case 1:
            action = GIC_IPI_EXT_INTR_RESCHED_VPE1;
            break;
      case 2:
            action = GIC_IPI_EXT_INTR_RESCHED_VPE2;
            break;
      case 3:
            action = GIC_IPI_EXT_INTR_RESCHED_VPE3;
            break;
      }
      gic_send_ipi(action);
}

/*
 * FIXME: This isn't restricted to CMP
 * The SMVP kernel could use GIC interrupts if available
 */
void cmp_send_ipi_single(int cpu, unsigned int action)
{
      unsigned long flags;

      local_irq_save(flags);

      switch (action) {
      case SMP_CALL_FUNCTION:
            ipi_call_function(cpu);
            break;

      case SMP_RESCHEDULE_YOURSELF:
            ipi_resched(cpu);
            break;
      }

      local_irq_restore(flags);
}

static void cmp_send_ipi_mask(cpumask_t mask, unsigned int action)
{
      unsigned int i;

      for_each_cpu_mask(i, mask)
            cmp_send_ipi_single(i, action);
}

static void cmp_init_secondary(void)
{
      struct cpuinfo_mips *c = &current_cpu_data;

      /* Assume GIC is present */
      change_c0_status(ST0_IM, STATUSF_IP3 | STATUSF_IP4 | STATUSF_IP6 |
                         STATUSF_IP7);

      /* Enable per-cpu interrupts: platform specific */

      c->core = (read_c0_ebase() >> 1) & 0xff;
#if defined(CONFIG_MIPS_MT_SMP) || defined(CONFIG_MIPS_MT_SMTC)
      c->vpe_id = (read_c0_tcbind() >> TCBIND_CURVPE_SHIFT) & TCBIND_CURVPE;
#endif
#ifdef CONFIG_MIPS_MT_SMTC
      c->tc_id  = (read_c0_tcbind() >> TCBIND_CURTC_SHIFT) & TCBIND_CURTC;
#endif
}

static void cmp_smp_finish(void)
{
      pr_debug("SMPCMP: CPU%d: %s\n", smp_processor_id(), __func__);

      /* CDFIXME: remove this? */
      write_c0_compare(read_c0_count() + (8 * mips_hpt_frequency / HZ));

#ifdef CONFIG_MIPS_MT_FPAFF
      /* If we have an FPU, enroll ourselves in the FPU-full mask */
      if (cpu_has_fpu)
            cpu_set(smp_processor_id(), mt_fpu_cpumask);
#endif /* CONFIG_MIPS_MT_FPAFF */

      local_irq_enable();
}

static void cmp_cpus_done(void)
{
      pr_debug("SMPCMP: CPU%d: %s\n", smp_processor_id(), __func__);
}

/*
 * Setup the PC, SP, and GP of a secondary processor and start it running
 * smp_bootstrap is the place to resume from
 * __KSTK_TOS(idle) is apparently the stack pointer
 * (unsigned long)idle->thread_info the gp
 */
static void cmp_boot_secondary(int cpu, struct task_struct *idle)
{
      struct thread_info *gp = task_thread_info(idle);
      unsigned long sp = __KSTK_TOS(idle);
      unsigned long pc = (unsigned long)&smp_bootstrap;
      unsigned long a0 = 0;

      pr_debug("SMPCMP: CPU%d: %s cpu %d\n", smp_processor_id(),
            __func__, cpu);

#if 0
      /* Needed? */
      flush_icache_range((unsigned long)gp,
                     (unsigned long)(gp + sizeof(struct thread_info)));
#endif

      amon_cpu_start(cpu, pc, sp, gp, a0);
}

/*
 * Common setup before any secondaries are started
 */
void __init cmp_smp_setup(void)
{
      int i;
      int ncpu = 0;

      pr_debug("SMPCMP: CPU%d: %s\n", smp_processor_id(), __func__);

#ifdef CONFIG_MIPS_MT_FPAFF
      /* If we have an FPU, enroll ourselves in the FPU-full mask */
      if (cpu_has_fpu)
            cpu_set(0, mt_fpu_cpumask);
#endif /* CONFIG_MIPS_MT_FPAFF */

      for (i = 1; i < NR_CPUS; i++) {
            if (amon_cpu_avail(i)) {
                  cpu_set(i, phys_cpu_present_map);
                  __cpu_number_map[i]     = ++ncpu;
                  __cpu_logical_map[ncpu] = i;
            }
      }

      if (cpu_has_mipsmt) {
            unsigned int nvpe, mvpconf0 = read_c0_mvpconf0();

            nvpe = ((mvpconf0 & MVPCONF0_PTC) >> MVPCONF0_PTC_SHIFT) + 1;
            smp_num_siblings = nvpe;
      }
      pr_info("Detected %i available secondary CPU(s)\n", ncpu);
}

void __init cmp_prepare_cpus(unsigned int max_cpus)
{
      pr_debug("SMPCMP: CPU%d: %s max_cpus=%d\n",
             smp_processor_id(), __func__, max_cpus);

      /*
       * FIXME: some of these options are per-system, some per-core and
       * some per-cpu
       */
      mips_mt_set_cpuoptions();
}

struct plat_smp_ops cmp_smp_ops = {
      .send_ipi_single  = cmp_send_ipi_single,
      .send_ipi_mask          = cmp_send_ipi_mask,
      .init_secondary         = cmp_init_secondary,
      .smp_finish       = cmp_smp_finish,
      .cpus_done        = cmp_cpus_done,
      .boot_secondary         = cmp_boot_secondary,
      .smp_setup        = cmp_smp_setup,
      .prepare_cpus           = cmp_prepare_cpus,
};

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