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