arch/x86/kernel/vmiclock_32.c

   1 /*
   2  * VMI paravirtual timer support routines.
   3  *
   4  * Copyright (C) 2007, VMware, Inc.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful, but
  12  * WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  14  * NON INFRINGEMENT.  See the GNU General Public License for more
  15  * details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20  *
  21  */
  22
  23 #include <linux/smp.h>
  24 #include <linux/interrupt.h>
  25 #include <linux/cpumask.h>
  26 #include <linux/clocksource.h>
  27 #include <linux/clockchips.h>
  28
  29 #include <asm/vmi.h>
  30 #include <asm/vmi_time.h>
  31 #include <asm/arch_hooks.h>
  32 #include <asm/apicdef.h>
  33 #include <asm/apic.h>
  34 #include <asm/timer.h>
  35 #include <asm/i8253.h>
  36
  37 #include <irq_vectors.h>
  38 #include "io_ports.h"
  39
  40 #define VMI_ONESHOT  (VMI_ALARM_IS_ONESHOT  | VMI_CYCLES_REAL | vmi_get_alarm_wiring())
  41 #define VMI_PERIODIC (VMI_ALARM_IS_PERIODIC | VMI_CYCLES_REAL | vmi_get_alarm_wiring())
  42
  43 static DEFINE_PER_CPU(struct clock_event_device, local_events);
  44
  45 static inline u32 vmi_counter(u32 flags)
  46 {
  47         /* Given VMI_ONESHOT or VMI_PERIODIC, return the corresponding
  48          * cycle counter. */
  49         return flags & VMI_ALARM_COUNTER_MASK;
  50 }
  51
  52 /* paravirt_ops.get_wallclock = vmi_get_wallclock */
  53 unsigned long vmi_get_wallclock(void)
  54 {
  55         unsigned long long wallclock;
  56         wallclock = vmi_timer_ops.get_wallclock(); // nsec
  57         (void)do_div(wallclock, 1000000000);       // sec
  58
  59         return wallclock;
  60 }
  61
  62 /* paravirt_ops.set_wallclock = vmi_set_wallclock */
  63 int vmi_set_wallclock(unsigned long now)
  64 {
  65         return 0;
  66 }
  67
  68 /* paravirt_ops.sched_clock = vmi_sched_clock */
  69 unsigned long long vmi_sched_clock(void)
  70 {
  71         return cycles_2_ns(vmi_timer_ops.get_cycle_counter(VMI_CYCLES_AVAILABLE));
  72 }
  73
  74 /* paravirt_ops.get_cpu_khz = vmi_cpu_khz */
  75 unsigned long vmi_cpu_khz(void)
  76 {
  77         unsigned long long khz;
  78         khz = vmi_timer_ops.get_cycle_frequency();
  79         (void)do_div(khz, 1000);
  80         return khz;
  81 }
  82
  83 static inline unsigned int vmi_get_timer_vector(void)
  84 {
  85 #ifdef CONFIG_X86_IO_APIC
  86         return FIRST_DEVICE_VECTOR;
  87 #else
  88         return FIRST_EXTERNAL_VECTOR;
  89 #endif
  90 }
  91
  92 /** vmi clockchip */
  93 #ifdef CONFIG_X86_LOCAL_APIC
  94 static unsigned int startup_timer_irq(unsigned int irq)
  95 {
  96         unsigned long val = apic_read(APIC_LVTT);
  97         apic_write(APIC_LVTT, vmi_get_timer_vector());
  98
  99         return (val & APIC_SEND_PENDING);
 100 }
 101
 102 static void mask_timer_irq(unsigned int irq)
 103 {
 104         unsigned long val = apic_read(APIC_LVTT);
 105         apic_write(APIC_LVTT, val | APIC_LVT_MASKED);
 106 }
 107
 108 static void unmask_timer_irq(unsigned int irq)
 109 {
 110         unsigned long val = apic_read(APIC_LVTT);
 111         apic_write(APIC_LVTT, val & ~APIC_LVT_MASKED);
 112 }
 113
 114 static void ack_timer_irq(unsigned int irq)
 115 {
 116         ack_APIC_irq();
 117 }
 118
 119 static struct irq_chip vmi_chip __read_mostly = {
 120         .name           = "VMI-LOCAL",
 121         .startup        = startup_timer_irq,
 122         .mask           = mask_timer_irq,
 123         .unmask         = unmask_timer_irq,
 124         .ack            = ack_timer_irq
 125 };
 126 #endif
 127
 128 /** vmi clockevent */
 129 #define VMI_ALARM_WIRED_IRQ0    0x00000000
 130 #define VMI_ALARM_WIRED_LVTT    0x00010000
 131 static int vmi_wiring = VMI_ALARM_WIRED_IRQ0;
 132
 133 static inline int vmi_get_alarm_wiring(void)
 134 {
 135         return vmi_wiring;
 136 }
 137
 138 static void vmi_timer_set_mode(enum clock_event_mode mode,
 139                                struct clock_event_device *evt)
 140 {
 141         cycle_t now, cycles_per_hz;
 142         BUG_ON(!irqs_disabled());
 143
 144         switch (mode) {
 145         case CLOCK_EVT_MODE_ONESHOT:
 146         case CLOCK_EVT_MODE_RESUME:
 147                 break;
 148         case CLOCK_EVT_MODE_PERIODIC:
 149                 cycles_per_hz = vmi_timer_ops.get_cycle_frequency();
 150                 (void)do_div(cycles_per_hz, HZ);
 151                 now = vmi_timer_ops.get_cycle_counter(vmi_counter(VMI_PERIODIC));
 152                 vmi_timer_ops.set_alarm(VMI_PERIODIC, now, cycles_per_hz);
 153                 break;
 154         case CLOCK_EVT_MODE_UNUSED:
 155         case CLOCK_EVT_MODE_SHUTDOWN:
 156                 switch (evt->mode) {
 157                 case CLOCK_EVT_MODE_ONESHOT:
 158                         vmi_timer_ops.cancel_alarm(VMI_ONESHOT);
 159                         break;
 160                 case CLOCK_EVT_MODE_PERIODIC:
 161                         vmi_timer_ops.cancel_alarm(VMI_PERIODIC);
 162                         break;
 163                 default:
 164                         break;
 165                 }
 166                 break;
 167         default:
 168                 break;
 169         }
 170 }
 171
 172 static int vmi_timer_next_event(unsigned long delta,
 173                                 struct clock_event_device *evt)
 174 {
 175         /* Unfortunately, set_next_event interface only passes relative
 176          * expiry, but we want absolute expiry.  It'd be better if were
 177          * were passed an aboslute expiry, since a bunch of time may
 178          * have been stolen between the time the delta is computed and
 179          * when we set the alarm below. */
 180         cycle_t now = vmi_timer_ops.get_cycle_counter(vmi_counter(VMI_ONESHOT));
 181
 182         BUG_ON(evt->mode != CLOCK_EVT_MODE_ONESHOT);
 183         vmi_timer_ops.set_alarm(VMI_ONESHOT, now + delta, 0);
 184         return 0;
 185 }
 186
 187 static struct clock_event_device vmi_clockevent = {
 188         .name           = "vmi-timer",
 189         .features       = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
 190         .shift          = 22,
 191         .set_mode       = vmi_timer_set_mode,
 192         .set_next_event = vmi_timer_next_event,
 193         .rating         = 1000,
 194         .irq            = 0,
 195 };
 196
 197 static irqreturn_t vmi_timer_interrupt(int irq, void *dev_id)
 198 {
 199         struct clock_event_device *evt = &__get_cpu_var(local_events);
 200         evt->event_handler(evt);
 201         return IRQ_HANDLED;
 202 }
 203
 204 static struct irqaction vmi_clock_action  = {
 205         .name           = "vmi-timer",
 206         .handler        = vmi_timer_interrupt,
 207         .flags          = IRQF_DISABLED | IRQF_NOBALANCING,
 208         .mask           = CPU_MASK_ALL,
 209 };
 210
 211 static void __devinit vmi_time_init_clockevent(void)
 212 {
 213         cycle_t cycles_per_msec;
 214         struct clock_event_device *evt;
 215
 216         int cpu = smp_processor_id();
 217         evt = &__get_cpu_var(local_events);
 218
 219         /* Use cycles_per_msec since div_sc params are 32-bits. */
 220         cycles_per_msec = vmi_timer_ops.get_cycle_frequency();
 221         (void)do_div(cycles_per_msec, 1000);
 222
 223         memcpy(evt, &vmi_clockevent, sizeof(*evt));
 224         /* Must pick .shift such that .mult fits in 32-bits.  Choosing
 225          * .shift to be 22 allows 2^(32-22) cycles per nano-seconds
 226          * before overflow. */
 227         evt->mult = div_sc(cycles_per_msec, NSEC_PER_MSEC, evt->shift);
 228         /* Upper bound is clockevent's use of ulong for cycle deltas. */
 229         evt->max_delta_ns = clockevent_delta2ns(ULONG_MAX, evt);
 230         evt->min_delta_ns = clockevent_delta2ns(1, evt);
 231         evt->cpumask = cpumask_of_cpu(cpu);
 232
 233         printk(KERN_WARNING "vmi: registering clock event %s. mult=%lu shift=%u\n",
 234                evt->name, evt->mult, evt->shift);
 235         clockevents_register_device(evt);
 236 }
 237
 238 void __init vmi_time_init(void)
 239 {
 240         /* Disable PIT: BIOSes start PIT CH0 with 18.2hz peridic. */
 241         outb_p(0x3a, PIT_MODE); /* binary, mode 5, LSB/MSB, ch 0 */
 242
 243         vmi_time_init_clockevent();
 244         setup_irq(0, &vmi_clock_action);
 245 }
 246
 247 #ifdef CONFIG_X86_LOCAL_APIC
 248 void __devinit vmi_time_bsp_init(void)
 249 {
 250         /*
 251          * On APIC systems, we want local timers to fire on each cpu.  We do
 252          * this by programming LVTT to deliver timer events to the IRQ handler
 253          * for IRQ-0, since we can't re-use the APIC local timer handler
 254          * without interfering with that code.
 255          */
 256         clockevents_notify(CLOCK_EVT_NOTIFY_SUSPEND, NULL);
 257         local_irq_disable();
 258 #ifdef CONFIG_X86_SMP
 259         /*
 260          * XXX handle_percpu_irq only defined for SMP; we need to switch over
 261          * to using it, since this is a local interrupt, which each CPU must
 262          * handle individually without locking out or dropping simultaneous
 263          * local timers on other CPUs.  We also don't want to trigger the
 264          * quirk workaround code for interrupts which gets invoked from
 265          * handle_percpu_irq via eoi, so we use our own IRQ chip.
 266          */
 267         set_irq_chip_and_handler_name(0, &vmi_chip, handle_percpu_irq, "lvtt");
 268 #else
 269         set_irq_chip_and_handler_name(0, &vmi_chip, handle_edge_irq, "lvtt");
 270 #endif
 271         vmi_wiring = VMI_ALARM_WIRED_LVTT;
 272         apic_write(APIC_LVTT, vmi_get_timer_vector());
 273         local_irq_enable();
 274         clockevents_notify(CLOCK_EVT_NOTIFY_RESUME, NULL);
 275 }
 276
 277 void __devinit vmi_time_ap_init(void)
 278 {
 279         vmi_time_init_clockevent();
 280         apic_write(APIC_LVTT, vmi_get_timer_vector());
 281 }
 282 #endif
 283
 284 /** vmi clocksource */
 285
 286 static cycle_t read_real_cycles(void)
 287 {
 288         return vmi_timer_ops.get_cycle_counter(VMI_CYCLES_REAL);
 289 }
 290
 291 static struct clocksource clocksource_vmi = {
 292         .name                   = "vmi-timer",
 293         .rating                 = 450,
 294         .read                   = read_real_cycles,
 295         .mask                   = CLOCKSOURCE_MASK(64),
 296         .mult                   = 0, /* to be set */
 297         .shift                  = 22,
 298         .flags                  = CLOCK_SOURCE_IS_CONTINUOUS,
 299 };
 300
 301 static int __init init_vmi_clocksource(void)
 302 {
 303         cycle_t cycles_per_msec;
 304
 305         if (!vmi_timer_ops.get_cycle_frequency)
 306                 return 0;
 307         /* Use khz2mult rather than hz2mult since hz arg is only 32-bits. */
 308         cycles_per_msec = vmi_timer_ops.get_cycle_frequency();
 309         (void)do_div(cycles_per_msec, 1000);
 310
 311         /* Note that clocksource.{mult, shift} converts in the opposite direction
 312          * as clockevents.  */
 313         clocksource_vmi.mult = clocksource_khz2mult(cycles_per_msec,
 314                                                     clocksource_vmi.shift);
 315
 316         printk(KERN_WARNING "vmi: registering clock source khz=%lld\n", cycles_per_msec);
 317         return clocksource_register(&clocksource_vmi);
 318
 319 }
 320 module_init(init_vmi_clocksource);