smp.c

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#include <linux/types.h>
#include <asm/delay.h>
#include <irq.h>
#include <hwregs/intr_vect.h>
#include <hwregs/intr_vect_defs.h>
#include <asm/tlbflush.h>
#include <asm/mmu_context.h>
#include <hwregs/asm/mmu_defs_asm.h>
#include <hwregs/supp_reg.h>
#include <linux/atomic.h>

#include <linux/err.h>
#include <linux/init.h>
#include <linux/timex.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/cpumask.h>
#include <linux/interrupt.h>
#include <linux/module.h>

#define IPI_SCHEDULE 1
#define IPI_CALL 2
#define IPI_FLUSH_TLB 4
#define IPI_BOOT 8

#define FLUSH_ALL (void*)0xffffffff

/* Vector of locks used for various atomic operations */
spinlock_t cris_atomic_locks[] = {
    [0 ... LOCK_COUNT - 1] = __SPIN_LOCK_UNLOCKED(cris_atomic_locks)
};

/* CPU masks */
cpumask_t phys_cpu_present_map = CPU_MASK_NONE;
EXPORT_SYMBOL(phys_cpu_present_map);

/* Variables used during SMP boot */
volatile int cpu_now_booting = 0;
volatile struct thread_info *smp_init_current_idle_thread;

/* Variables used during IPI */
static DEFINE_SPINLOCK(call_lock);
static DEFINE_SPINLOCK(tlbstate_lock);

struct call_data_struct {
    void (*func) (void *info);
    void *info;
    int wait;
};

static struct call_data_struct * call_data;

static struct mm_struct* flush_mm;
static struct vm_area_struct* flush_vma;
static unsigned long flush_addr;

/* Mode registers */
static unsigned long irq_regs[NR_CPUS] = {
  regi_irq,
  regi_irq2
};

static irqreturn_t crisv32_ipi_interrupt(int irq, void *dev_id);
static int send_ipi(int vector, int wait, cpumask_t cpu_mask);
static struct irqaction irq_ipi  = {
    .handler = crisv32_ipi_interrupt,
    .flags = IRQF_DISABLED,
    .name = "ipi",
};

extern void cris_mmu_init(void);
extern void cris_timer_init(void);

/* SMP initialization */
void __init smp_prepare_cpus(unsigned int max_cpus)
{
    int i;

    /* From now on we can expect IPIs so set them up */
    setup_irq(IPI_INTR_VECT, &irq_ipi);

    /* Mark all possible CPUs as present */
    for (i = 0; i < max_cpus; i++)
        cpumask_set_cpu(i, &phys_cpu_present_map);
}

void __devinit smp_prepare_boot_cpu(void)
{
    /* PGD pointer has moved after per_cpu initialization so
     * update the MMU.
     */
    pgd_t **pgd;
    pgd = (pgd_t**)&per_cpu(current_pgd, smp_processor_id());

    SUPP_BANK_SEL(1);
    SUPP_REG_WR(RW_MM_TLB_PGD, pgd);
    SUPP_BANK_SEL(2);
    SUPP_REG_WR(RW_MM_TLB_PGD, pgd);

    set_cpu_online(0, true);
    cpumask_set_cpu(0, &phys_cpu_present_map);
    set_cpu_possible(0, true);
}

void __init smp_cpus_done(unsigned int max_cpus)
{
}

/* Bring one cpu online.*/
static int __init
smp_boot_one_cpu(int cpuid, struct task_struct idle)
{
    unsigned timeout;
    cpumask_t cpu_mask;

    cpumask_clear(&cpu_mask);
    task_thread_info(idle)->cpu = cpuid;

    /* Information to the CPU that is about to boot */
    smp_init_current_idle_thread = task_thread_info(idle);
    cpu_now_booting = cpuid;

    /* Kick it */
    set_cpu_online(cpuid, true);
    cpumask_set_cpu(cpuid, &cpu_mask);
    send_ipi(IPI_BOOT, 0, cpu_mask);
    set_cpu_online(cpuid, false);

    /* Wait for CPU to come online */
    for (timeout = 0; timeout < 10000; timeout++) {
        if(cpu_online(cpuid)) {
            cpu_now_booting = 0;
            smp_init_current_idle_thread = NULL;
            return 0; /* CPU online */
        }
        udelay(100);
        barrier();
    }

    printk(KERN_CRIT "SMP: CPU:%d is stuck.\n", cpuid);
    return -1;
}

/* Secondary CPUs starts using C here. Here we need to setup CPU
 * specific stuff such as the local timer and the MMU. */
void __init smp_callin(void)
{
    extern void cpu_idle(void);

    int cpu = cpu_now_booting;
    reg_intr_vect_rw_mask vect_mask = {0};

    /* Initialise the idle task for this CPU */
    atomic_inc(&init_mm.mm_count);
    current->active_mm = &init_mm;

    /* Set up MMU */
    cris_mmu_init();
    __flush_tlb_all();

    /* Setup local timer. */
    cris_timer_init();

    /* Enable IRQ and idle */
    REG_WR(intr_vect, irq_regs[cpu], rw_mask, vect_mask);
    crisv32_unmask_irq(IPI_INTR_VECT);
    crisv32_unmask_irq(TIMER0_INTR_VECT);
    preempt_disable();
    notify_cpu_starting(cpu);
    local_irq_enable();

    set_cpu_online(cpu, true);
    cpu_idle();
}

/* Stop execution on this CPU.*/
void stop_this_cpu(void* dummy)
{
    local_irq_disable();
    asm volatile("halt");
}

/* Other calls */
void smp_send_stop(void)
{
    smp_call_function(stop_this_cpu, NULL, 0);
}

int setup_profiling_timer(unsigned int multiplier)
{
    return -EINVAL;
}


/* cache_decay_ticks is used by the scheduler to decide if a process
 * is "hot" on one CPU. A higher value means a higher penalty to move
 * a process to another CPU. Our cache is rather small so we report
 * 1 tick.
 */
unsigned long cache_decay_ticks = 1;

int __cpuinit __cpu_up(unsigned int cpu, struct task_struct *tidle)
{
    smp_boot_one_cpu(cpu, tidle);
    return cpu_online(cpu) ? 0 : -ENOSYS;
}

void smp_send_reschedule(int cpu)
{
    cpumask_t cpu_mask;
    cpumask_clear(&cpu_mask);
    cpumask_set_cpu(cpu, &cpu_mask);
    send_ipi(IPI_SCHEDULE, 0, cpu_mask);
}

/* TLB flushing
 *
 * Flush needs to be done on the local CPU and on any other CPU that
 * may have the same mapping. The mm->cpu_vm_mask is used to keep track
 * of which CPUs that a specific process has been executed on.
 */
void flush_tlb_common(struct mm_struct* mm, struct vm_area_struct* vma, unsigned long addr)
{
    unsigned long flags;
    cpumask_t cpu_mask;

    spin_lock_irqsave(&tlbstate_lock, flags);
    cpu_mask = (mm == FLUSH_ALL ? cpu_all_mask : *mm_cpumask(mm));
    cpumask_clear_cpu(smp_processor_id(), &cpu_mask);
    flush_mm = mm;
    flush_vma = vma;
    flush_addr = addr;
    send_ipi(IPI_FLUSH_TLB, 1, cpu_mask);
    spin_unlock_irqrestore(&tlbstate_lock, flags);
}

void flush_tlb_all(void)
{
    __flush_tlb_all();
    flush_tlb_common(FLUSH_ALL, FLUSH_ALL, 0);
}

void flush_tlb_mm(struct mm_struct *mm)
{
    __flush_tlb_mm(mm);
    flush_tlb_common(mm, FLUSH_ALL, 0);
    /* No more mappings in other CPUs */
    cpumask_clear(mm_cpumask(mm));
    cpumask_set_cpu(smp_processor_id(), mm_cpumask(mm));
}

void flush_tlb_page(struct vm_area_struct *vma,
               unsigned long addr)
{
    __flush_tlb_page(vma, addr);
    flush_tlb_common(vma->vm_mm, vma, addr);
}

/* Inter processor interrupts
 *
 * The IPIs are used for:
 *   * Force a schedule on a CPU
 *   * FLush TLB on other CPUs
 *   * Call a function on other CPUs
 */

int send_ipi(int vector, int wait, cpumask_t cpu_mask)
{
    int i = 0;
    reg_intr_vect_rw_ipi ipi = REG_RD(intr_vect, irq_regs[i], rw_ipi);
    int ret = 0;

    /* Calculate CPUs to send to. */
    cpumask_and(&cpu_mask, &cpu_mask, cpu_online_mask);

    /* Send the IPI. */
    for_each_cpu(i, &cpu_mask)
    {
        ipi.vector |= vector;
        REG_WR(intr_vect, irq_regs[i], rw_ipi, ipi);
    }

    /* Wait for IPI to finish on other CPUS */
    if (wait) {
        for_each_cpu(i, &cpu_mask) {
                        int j;
                        for (j = 0 ; j < 1000; j++) {
                ipi = REG_RD(intr_vect, irq_regs[i], rw_ipi);
                if (!ipi.vector)
                    break;
                udelay(100);
            }

            /* Timeout? */
            if (ipi.vector) {
                printk("SMP call timeout from %d to %d\n", smp_processor_id(), i);
                ret = -ETIMEDOUT;
                dump_stack();
            }
        }
    }
    return ret;
}

/*
 * You must not call this function with disabled interrupts or from a
 * hardware interrupt handler or from a bottom half handler.
 */
int smp_call_function(void (*func)(void *info), void *info, int wait)
{
    cpumask_t cpu_mask;
    struct call_data_struct data;
    int ret;

    cpumask_setall(&cpu_mask);
    cpumask_clear_cpu(smp_processor_id(), &cpu_mask);

    WARN_ON(irqs_disabled());

    data.func = func;
    data.info = info;
    data.wait = wait;

    spin_lock(&call_lock);
    call_data = &data;
    ret = send_ipi(IPI_CALL, wait, cpu_mask);
    spin_unlock(&call_lock);

    return ret;
}

irqreturn_t crisv32_ipi_interrupt(int irq, void *dev_id)
{
    void (*func) (void *info) = call_data->func;
    void *info = call_data->info;
    reg_intr_vect_rw_ipi ipi;

    ipi = REG_RD(intr_vect, irq_regs[smp_processor_id()], rw_ipi);

    if (ipi.vector & IPI_SCHEDULE) {
        scheduler_ipi();
    }
    if (ipi.vector & IPI_CALL) {
        func(info);
    }
    if (ipi.vector & IPI_FLUSH_TLB) {
        if (flush_mm == FLUSH_ALL)
            __flush_tlb_all();
        else if (flush_vma == FLUSH_ALL)
            __flush_tlb_mm(flush_mm);
        else
            __flush_tlb_page(flush_vma, flush_addr);
    }

    ipi.vector = 0;
    REG_WR(intr_vect, irq_regs[smp_processor_id()], rw_ipi, ipi);

    return IRQ_HANDLED;
}