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vmiclock_32.c

/*
 * VMI paravirtual timer support routines.
 *
 * Copyright (C) 2007, VMware, Inc.
 *
 * 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, GOOD TITLE or
 * NON INFRINGEMENT.  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., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 */

#include <linux/smp.h>
#include <linux/interrupt.h>
#include <linux/cpumask.h>
#include <linux/clocksource.h>
#include <linux/clockchips.h>

#include <asm/vmi.h>
#include <asm/vmi_time.h>
#include <asm/arch_hooks.h>
#include <asm/apicdef.h>
#include <asm/apic.h>
#include <asm/timer.h>
#include <asm/i8253.h>

#include <irq_vectors.h>
#include "io_ports.h"

#define VMI_ONESHOT  (VMI_ALARM_IS_ONESHOT  | VMI_CYCLES_REAL | vmi_get_alarm_wiring())
#define VMI_PERIODIC (VMI_ALARM_IS_PERIODIC | VMI_CYCLES_REAL | vmi_get_alarm_wiring())

static DEFINE_PER_CPU(struct clock_event_device, local_events);

static inline u32 vmi_counter(u32 flags)
{
      /* Given VMI_ONESHOT or VMI_PERIODIC, return the corresponding
       * cycle counter. */
      return flags & VMI_ALARM_COUNTER_MASK;
}

/* paravirt_ops.get_wallclock = vmi_get_wallclock */
unsigned long vmi_get_wallclock(void)
{
      unsigned long long wallclock;
      wallclock = vmi_timer_ops.get_wallclock(); // nsec
      (void)do_div(wallclock, 1000000000);       // sec

      return wallclock;
}

/* paravirt_ops.set_wallclock = vmi_set_wallclock */
int vmi_set_wallclock(unsigned long now)
{
      return 0;
}

/* paravirt_ops.sched_clock = vmi_sched_clock */
unsigned long long vmi_sched_clock(void)
{
      return cycles_2_ns(vmi_timer_ops.get_cycle_counter(VMI_CYCLES_AVAILABLE));
}

/* paravirt_ops.get_cpu_khz = vmi_cpu_khz */
unsigned long vmi_cpu_khz(void)
{
      unsigned long long khz;
      khz = vmi_timer_ops.get_cycle_frequency();
      (void)do_div(khz, 1000);
      return khz;
}

static inline unsigned int vmi_get_timer_vector(void)
{
#ifdef CONFIG_X86_IO_APIC
      return FIRST_DEVICE_VECTOR;
#else
      return FIRST_EXTERNAL_VECTOR;
#endif
}

/** vmi clockchip */
#ifdef CONFIG_X86_LOCAL_APIC
static unsigned int startup_timer_irq(unsigned int irq)
{
      unsigned long val = apic_read(APIC_LVTT);
      apic_write(APIC_LVTT, vmi_get_timer_vector());

      return (val & APIC_SEND_PENDING);
}

static void mask_timer_irq(unsigned int irq)
{
      unsigned long val = apic_read(APIC_LVTT);
      apic_write(APIC_LVTT, val | APIC_LVT_MASKED);
}

static void unmask_timer_irq(unsigned int irq)
{
      unsigned long val = apic_read(APIC_LVTT);
      apic_write(APIC_LVTT, val & ~APIC_LVT_MASKED);
}

static void ack_timer_irq(unsigned int irq)
{
      ack_APIC_irq();
}

static struct irq_chip vmi_chip __read_mostly = {
      .name             = "VMI-LOCAL",
      .startup    = startup_timer_irq,
      .mask       = mask_timer_irq,
      .unmask           = unmask_timer_irq,
      .ack        = ack_timer_irq
};
#endif

/** vmi clockevent */
#define VMI_ALARM_WIRED_IRQ0    0x00000000
#define VMI_ALARM_WIRED_LVTT    0x00010000
static int vmi_wiring = VMI_ALARM_WIRED_IRQ0;

static inline int vmi_get_alarm_wiring(void)
{
      return vmi_wiring;
}

static void vmi_timer_set_mode(enum clock_event_mode mode,
                         struct clock_event_device *evt)
{
      cycle_t now, cycles_per_hz;
      BUG_ON(!irqs_disabled());

      switch (mode) {
      case CLOCK_EVT_MODE_ONESHOT:
      case CLOCK_EVT_MODE_RESUME:
            break;
      case CLOCK_EVT_MODE_PERIODIC:
            cycles_per_hz = vmi_timer_ops.get_cycle_frequency();
            (void)do_div(cycles_per_hz, HZ);
            now = vmi_timer_ops.get_cycle_counter(vmi_counter(VMI_PERIODIC));
            vmi_timer_ops.set_alarm(VMI_PERIODIC, now, cycles_per_hz);
            break;
      case CLOCK_EVT_MODE_UNUSED:
      case CLOCK_EVT_MODE_SHUTDOWN:
            switch (evt->mode) {
            case CLOCK_EVT_MODE_ONESHOT:
                  vmi_timer_ops.cancel_alarm(VMI_ONESHOT);
                  break;
            case CLOCK_EVT_MODE_PERIODIC:
                  vmi_timer_ops.cancel_alarm(VMI_PERIODIC);
                  break;
            default:
                  break;
            }
            break;
      default:
            break;
      }
}

static int vmi_timer_next_event(unsigned long delta,
                        struct clock_event_device *evt)
{
      /* Unfortunately, set_next_event interface only passes relative
       * expiry, but we want absolute expiry.  It'd be better if were
       * were passed an aboslute expiry, since a bunch of time may
       * have been stolen between the time the delta is computed and
       * when we set the alarm below. */
      cycle_t now = vmi_timer_ops.get_cycle_counter(vmi_counter(VMI_ONESHOT));

      BUG_ON(evt->mode != CLOCK_EVT_MODE_ONESHOT);
      vmi_timer_ops.set_alarm(VMI_ONESHOT, now + delta, 0);
      return 0;
}

static struct clock_event_device vmi_clockevent = {
      .name       = "vmi-timer",
      .features   = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
      .shift            = 22,
      .set_mode   = vmi_timer_set_mode,
      .set_next_event = vmi_timer_next_event,
      .rating         = 1000,
      .irq        = 0,
};

static irqreturn_t vmi_timer_interrupt(int irq, void *dev_id)
{
      struct clock_event_device *evt = &__get_cpu_var(local_events);
      evt->event_handler(evt);
      return IRQ_HANDLED;
}

static struct irqaction vmi_clock_action  = {
      .name             = "vmi-timer",
      .handler    = vmi_timer_interrupt,
      .flags            = IRQF_DISABLED | IRQF_NOBALANCING,
      .mask             = CPU_MASK_ALL,
};

static void __devinit vmi_time_init_clockevent(void)
{
      cycle_t cycles_per_msec;
      struct clock_event_device *evt;

      int cpu = smp_processor_id();
      evt = &__get_cpu_var(local_events);

      /* Use cycles_per_msec since div_sc params are 32-bits. */
      cycles_per_msec = vmi_timer_ops.get_cycle_frequency();
      (void)do_div(cycles_per_msec, 1000);

      memcpy(evt, &vmi_clockevent, sizeof(*evt));
      /* Must pick .shift such that .mult fits in 32-bits.  Choosing
       * .shift to be 22 allows 2^(32-22) cycles per nano-seconds
       * before overflow. */
      evt->mult = div_sc(cycles_per_msec, NSEC_PER_MSEC, evt->shift);
      /* Upper bound is clockevent's use of ulong for cycle deltas. */
      evt->max_delta_ns = clockevent_delta2ns(ULONG_MAX, evt);
      evt->min_delta_ns = clockevent_delta2ns(1, evt);
      evt->cpumask = cpumask_of_cpu(cpu);

      printk(KERN_WARNING "vmi: registering clock event %s. mult=%lu shift=%u\n",
             evt->name, evt->mult, evt->shift);
      clockevents_register_device(evt);
}

void __init vmi_time_init(void)
{
      /* Disable PIT: BIOSes start PIT CH0 with 18.2hz peridic. */
      outb_p(0x3a, PIT_MODE); /* binary, mode 5, LSB/MSB, ch 0 */

      vmi_time_init_clockevent();
      setup_irq(0, &vmi_clock_action);
}

#ifdef CONFIG_X86_LOCAL_APIC
void __devinit vmi_time_bsp_init(void)
{
      /*
       * On APIC systems, we want local timers to fire on each cpu.  We do
       * this by programming LVTT to deliver timer events to the IRQ handler
       * for IRQ-0, since we can't re-use the APIC local timer handler
       * without interfering with that code.
       */
      clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL);
      local_irq_disable();
#ifdef CONFIG_X86_SMP
      /*
       * XXX handle_percpu_irq only defined for SMP; we need to switch over
       * to using it, since this is a local interrupt, which each CPU must
       * handle individually without locking out or dropping simultaneous
       * local timers on other CPUs.  We also don't want to trigger the
       * quirk workaround code for interrupts which gets invoked from
       * handle_percpu_irq via eoi, so we use our own IRQ chip.
       */
      set_irq_chip_and_handler_name(0, &vmi_chip, handle_percpu_irq, "lvtt");
#else
      set_irq_chip_and_handler_name(0, &vmi_chip, handle_edge_irq, "lvtt");
#endif
      vmi_wiring = VMI_ALARM_WIRED_LVTT;
      apic_write(APIC_LVTT, vmi_get_timer_vector());
      local_irq_enable();
      clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL);
}

void __devinit vmi_time_ap_init(void)
{
      vmi_time_init_clockevent();
      apic_write(APIC_LVTT, vmi_get_timer_vector());
}
#endif

/** vmi clocksource */

static cycle_t read_real_cycles(void)
{
      return vmi_timer_ops.get_cycle_counter(VMI_CYCLES_REAL);
}

static struct clocksource clocksource_vmi = {
      .name             = "vmi-timer",
      .rating                 = 450,
      .read             = read_real_cycles,
      .mask             = CLOCKSOURCE_MASK(64),
      .mult             = 0, /* to be set */
      .shift                  = 22,
      .flags                  = CLOCK_SOURCE_IS_CONTINUOUS,
};

static int __init init_vmi_clocksource(void)
{
      cycle_t cycles_per_msec;

      if (!vmi_timer_ops.get_cycle_frequency)
            return 0;
      /* Use khz2mult rather than hz2mult since hz arg is only 32-bits. */
      cycles_per_msec = vmi_timer_ops.get_cycle_frequency();
      (void)do_div(cycles_per_msec, 1000);

      /* Note that clocksource.{mult, shift} converts in the opposite direction
       * as clockevents.  */
      clocksource_vmi.mult = clocksource_khz2mult(cycles_per_msec,
                                        clocksource_vmi.shift);

      printk(KERN_WARNING "vmi: registering clock source khz=%lld\n", cycles_per_msec);
      return clocksource_register(&clocksource_vmi);

}
module_init(init_vmi_clocksource);

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