aboutsummaryrefslogtreecommitdiffstats
path: root/arch/x86/kernel/vmiclock_32.c
blob: 2f1ca56142928af1a98e6a9358bd758cfd282513 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
/*
 * 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/apicdef.h>
#include <asm/apic.h>
#include <asm/timer.h>
#include <asm/i8253.h>
#include <asm/irq_vectors.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));
}

/* x86_platform.calibrate_tsc = vmi_tsc_khz */
unsigned long vmi_tsc_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)
{
	return IRQ0_VECTOR;
}

/** 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 | IRQF_TIMER,
};

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);

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

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

	vmi_time_init_clockevent();
	setup_irq(0, &vmi_clock_action);
	for_each_possible_cpu(cpu)
		per_cpu(vector_irq, cpu)[vmi_get_timer_vector()] = 0;
}

#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_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 struct clocksource clocksource_vmi;

static cycle_t read_real_cycles(struct clocksource *cs)
{
	cycle_t ret = (cycle_t)vmi_timer_ops.get_cycle_counter(VMI_CYCLES_REAL);
	return max(ret, clocksource_vmi.cycle_last);
}

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);