The Linux kernel driver was updated in commit 4451d3f59f2a
("clocksource/drivers/fttmr010: Fix set_next_event handler) to fix an
issue observed on hardware:
> RELOAD register is loaded into COUNT register when the aspeed timer
> is enabled, which means the next event may be delayed because timer
> interrupt won't be generated until <0xFFFFFFFF - current_count +
> cycles>.
When running under Qemu, the system appeared "laggy". The guest is now
scheduling timer events too regularly, starving the host of CPU time.
This patch modifies the timer model to attempt to schedule the timer
expiry as the guest requests, but if we have missed the deadline we
re interrupt and try again, which allows the guest to catch up.
Provides expected behaviour with old and new guest code.
Fixes: c04bd47db6
("hw/timer: Add ASPEED timer device model")
Signed-off-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Message-id: 20190618165311.27066-8-clg@kaod.org
[clg: - merged a fix from Andrew Jeffery <andrew@aj.id.au>
"Fire interrupt on failure to meet deadline"
https://lists.ozlabs.org/pipermail/openbmc/2019-January/014641.html
- adapted commit log
- checkpatch fixes ]
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
548 lines
15 KiB
C
548 lines
15 KiB
C
/*
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* ASPEED AST2400 Timer
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*
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* Andrew Jeffery <andrew@aj.id.au>
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*
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* Copyright (C) 2016 IBM Corp.
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*
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* This code is licensed under the GPL version 2 or later. See
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* the COPYING file in the top-level directory.
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*/
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#include "qemu/osdep.h"
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#include "qapi/error.h"
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#include "hw/sysbus.h"
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#include "hw/timer/aspeed_timer.h"
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#include "qemu/bitops.h"
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#include "qemu/timer.h"
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#include "qemu/log.h"
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#include "qemu/module.h"
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#include "trace.h"
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#define TIMER_NR_REGS 4
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#define TIMER_CTRL_BITS 4
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#define TIMER_CTRL_MASK ((1 << TIMER_CTRL_BITS) - 1)
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#define TIMER_CLOCK_USE_EXT true
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#define TIMER_CLOCK_EXT_HZ 1000000
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#define TIMER_CLOCK_USE_APB false
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#define TIMER_REG_STATUS 0
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#define TIMER_REG_RELOAD 1
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#define TIMER_REG_MATCH_FIRST 2
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#define TIMER_REG_MATCH_SECOND 3
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#define TIMER_FIRST_CAP_PULSE 4
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enum timer_ctrl_op {
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op_enable = 0,
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op_external_clock,
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op_overflow_interrupt,
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op_pulse_enable
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};
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/**
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* Avoid mutual references between AspeedTimerCtrlState and AspeedTimer
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* structs, as it's a waste of memory. The ptimer BH callback needs to know
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* whether a specific AspeedTimer is enabled, but this information is held in
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* AspeedTimerCtrlState. So, provide a helper to hoist ourselves from an
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* arbitrary AspeedTimer to AspeedTimerCtrlState.
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*/
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static inline AspeedTimerCtrlState *timer_to_ctrl(AspeedTimer *t)
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{
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const AspeedTimer (*timers)[] = (void *)t - (t->id * sizeof(*t));
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return container_of(timers, AspeedTimerCtrlState, timers);
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}
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static inline bool timer_ctrl_status(AspeedTimer *t, enum timer_ctrl_op op)
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{
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return !!(timer_to_ctrl(t)->ctrl & BIT(t->id * TIMER_CTRL_BITS + op));
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}
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static inline bool timer_enabled(AspeedTimer *t)
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{
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return timer_ctrl_status(t, op_enable);
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}
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static inline bool timer_overflow_interrupt(AspeedTimer *t)
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{
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return timer_ctrl_status(t, op_overflow_interrupt);
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}
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static inline bool timer_can_pulse(AspeedTimer *t)
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{
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return t->id >= TIMER_FIRST_CAP_PULSE;
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}
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static inline bool timer_external_clock(AspeedTimer *t)
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{
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return timer_ctrl_status(t, op_external_clock);
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}
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static inline uint32_t calculate_rate(struct AspeedTimer *t)
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{
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AspeedTimerCtrlState *s = timer_to_ctrl(t);
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return timer_external_clock(t) ? TIMER_CLOCK_EXT_HZ : s->scu->apb_freq;
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}
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static inline uint32_t calculate_ticks(struct AspeedTimer *t, uint64_t now_ns)
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{
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uint64_t delta_ns = now_ns - MIN(now_ns, t->start);
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uint32_t rate = calculate_rate(t);
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uint64_t ticks = muldiv64(delta_ns, rate, NANOSECONDS_PER_SECOND);
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return t->reload - MIN(t->reload, ticks);
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}
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static inline uint64_t calculate_time(struct AspeedTimer *t, uint32_t ticks)
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{
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uint64_t delta_ns;
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uint64_t delta_ticks;
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delta_ticks = t->reload - MIN(t->reload, ticks);
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delta_ns = muldiv64(delta_ticks, NANOSECONDS_PER_SECOND, calculate_rate(t));
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return t->start + delta_ns;
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}
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static uint64_t calculate_next(struct AspeedTimer *t)
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{
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uint64_t now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
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uint64_t next;
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/*
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* We don't know the relationship between the values in the match
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* registers, so sort using MAX/MIN/zero. We sort in that order as
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* the timer counts down to zero.
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*/
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next = calculate_time(t, MAX(t->match[0], t->match[1]));
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if (now < next) {
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return next;
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}
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next = calculate_time(t, MIN(t->match[0], t->match[1]));
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if (now < next) {
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return next;
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}
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next = calculate_time(t, 0);
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if (now < next) {
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return next;
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}
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/* We've missed all deadlines, fire interrupt and try again */
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timer_del(&t->timer);
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if (timer_overflow_interrupt(t)) {
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t->level = !t->level;
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qemu_set_irq(t->irq, t->level);
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}
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t->start = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
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return calculate_time(t, MAX(MAX(t->match[0], t->match[1]), 0));
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}
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static void aspeed_timer_mod(AspeedTimer *t)
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{
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uint64_t next = calculate_next(t);
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if (next) {
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timer_mod(&t->timer, next);
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}
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}
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static void aspeed_timer_expire(void *opaque)
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{
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AspeedTimer *t = opaque;
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bool interrupt = false;
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uint32_t ticks;
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if (!timer_enabled(t)) {
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return;
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}
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ticks = calculate_ticks(t, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL));
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if (!ticks) {
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interrupt = timer_overflow_interrupt(t) || !t->match[0] || !t->match[1];
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} else if (ticks <= MIN(t->match[0], t->match[1])) {
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interrupt = true;
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} else if (ticks <= MAX(t->match[0], t->match[1])) {
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interrupt = true;
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}
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if (interrupt) {
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t->level = !t->level;
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qemu_set_irq(t->irq, t->level);
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}
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aspeed_timer_mod(t);
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}
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static uint64_t aspeed_timer_get_value(AspeedTimer *t, int reg)
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{
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uint64_t value;
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switch (reg) {
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case TIMER_REG_STATUS:
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value = calculate_ticks(t, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL));
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break;
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case TIMER_REG_RELOAD:
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value = t->reload;
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break;
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case TIMER_REG_MATCH_FIRST:
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case TIMER_REG_MATCH_SECOND:
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value = t->match[reg - 2];
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break;
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default:
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qemu_log_mask(LOG_UNIMP, "%s: Programming error: unexpected reg: %d\n",
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__func__, reg);
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value = 0;
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break;
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}
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return value;
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}
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static uint64_t aspeed_timer_read(void *opaque, hwaddr offset, unsigned size)
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{
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AspeedTimerCtrlState *s = opaque;
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const int reg = (offset & 0xf) / 4;
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uint64_t value;
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switch (offset) {
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case 0x30: /* Control Register */
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value = s->ctrl;
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break;
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case 0x34: /* Control Register 2 */
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value = s->ctrl2;
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break;
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case 0x00 ... 0x2c: /* Timers 1 - 4 */
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value = aspeed_timer_get_value(&s->timers[(offset >> 4)], reg);
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break;
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case 0x40 ... 0x8c: /* Timers 5 - 8 */
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value = aspeed_timer_get_value(&s->timers[(offset >> 4) - 1], reg);
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break;
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/* Illegal */
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case 0x38:
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case 0x3C:
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default:
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qemu_log_mask(LOG_GUEST_ERROR, "%s: Bad offset 0x%" HWADDR_PRIx "\n",
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__func__, offset);
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value = 0;
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break;
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}
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trace_aspeed_timer_read(offset, size, value);
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return value;
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}
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static void aspeed_timer_set_value(AspeedTimerCtrlState *s, int timer, int reg,
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uint32_t value)
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{
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AspeedTimer *t;
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uint32_t old_reload;
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trace_aspeed_timer_set_value(timer, reg, value);
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t = &s->timers[timer];
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switch (reg) {
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case TIMER_REG_RELOAD:
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old_reload = t->reload;
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t->reload = value;
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/* If the reload value was not previously set, or zero, and
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* the current value is valid, try to start the timer if it is
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* enabled.
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*/
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if (old_reload || !t->reload) {
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break;
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}
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case TIMER_REG_STATUS:
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if (timer_enabled(t)) {
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uint64_t now = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
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int64_t delta = (int64_t) value - (int64_t) calculate_ticks(t, now);
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uint32_t rate = calculate_rate(t);
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t->start += muldiv64(delta, NANOSECONDS_PER_SECOND, rate);
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aspeed_timer_mod(t);
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}
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break;
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case TIMER_REG_MATCH_FIRST:
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case TIMER_REG_MATCH_SECOND:
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t->match[reg - 2] = value;
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if (timer_enabled(t)) {
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aspeed_timer_mod(t);
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}
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break;
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default:
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qemu_log_mask(LOG_UNIMP, "%s: Programming error: unexpected reg: %d\n",
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__func__, reg);
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break;
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}
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}
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/* Control register operations are broken out into helpers that can be
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* explicitly called on aspeed_timer_reset(), but also from
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* aspeed_timer_ctrl_op().
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*/
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static void aspeed_timer_ctrl_enable(AspeedTimer *t, bool enable)
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{
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trace_aspeed_timer_ctrl_enable(t->id, enable);
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if (enable) {
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t->start = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
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aspeed_timer_mod(t);
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} else {
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timer_del(&t->timer);
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}
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}
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static void aspeed_timer_ctrl_external_clock(AspeedTimer *t, bool enable)
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{
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trace_aspeed_timer_ctrl_external_clock(t->id, enable);
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}
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static void aspeed_timer_ctrl_overflow_interrupt(AspeedTimer *t, bool enable)
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{
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trace_aspeed_timer_ctrl_overflow_interrupt(t->id, enable);
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}
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static void aspeed_timer_ctrl_pulse_enable(AspeedTimer *t, bool enable)
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{
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if (timer_can_pulse(t)) {
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trace_aspeed_timer_ctrl_pulse_enable(t->id, enable);
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} else {
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qemu_log_mask(LOG_GUEST_ERROR,
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"%s: Timer does not support pulse mode\n", __func__);
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}
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}
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/**
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* Given the actions are fixed in number and completely described in helper
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* functions, dispatch with a lookup table rather than manage control flow with
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* a switch statement.
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*/
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static void (*const ctrl_ops[])(AspeedTimer *, bool) = {
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[op_enable] = aspeed_timer_ctrl_enable,
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[op_external_clock] = aspeed_timer_ctrl_external_clock,
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[op_overflow_interrupt] = aspeed_timer_ctrl_overflow_interrupt,
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[op_pulse_enable] = aspeed_timer_ctrl_pulse_enable,
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};
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/**
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* Conditionally affect changes chosen by a timer's control bit.
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*
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* The aspeed_timer_ctrl_op() interface is convenient for the
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* aspeed_timer_set_ctrl() function as the "no change" early exit can be
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* calculated for all operations, which cleans up the caller code. However the
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* interface isn't convenient for the reset function where we want to enter a
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* specific state without artificially constructing old and new values that
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* will fall through the change guard (and motivates extracting the actions
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* out to helper functions).
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*
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* @t: The timer to manipulate
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* @op: The type of operation to be performed
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* @old: The old state of the timer's control bits
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* @new: The incoming state for the timer's control bits
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*/
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static void aspeed_timer_ctrl_op(AspeedTimer *t, enum timer_ctrl_op op,
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uint8_t old, uint8_t new)
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{
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const uint8_t mask = BIT(op);
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const bool enable = !!(new & mask);
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const bool changed = ((old ^ new) & mask);
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if (!changed) {
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return;
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}
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ctrl_ops[op](t, enable);
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}
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static void aspeed_timer_set_ctrl(AspeedTimerCtrlState *s, uint32_t reg)
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{
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int i;
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int shift;
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uint8_t t_old, t_new;
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AspeedTimer *t;
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const uint8_t enable_mask = BIT(op_enable);
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/* Handle a dependency between the 'enable' and remaining three
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* configuration bits - i.e. if more than one bit in the control set has
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* changed, including the 'enable' bit, then we want either disable the
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* timer and perform configuration, or perform configuration and then
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* enable the timer
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*/
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for (i = 0; i < ASPEED_TIMER_NR_TIMERS; i++) {
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t = &s->timers[i];
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shift = (i * TIMER_CTRL_BITS);
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t_old = (s->ctrl >> shift) & TIMER_CTRL_MASK;
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t_new = (reg >> shift) & TIMER_CTRL_MASK;
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/* If we are disabling, do so first */
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if ((t_old & enable_mask) && !(t_new & enable_mask)) {
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aspeed_timer_ctrl_enable(t, false);
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}
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aspeed_timer_ctrl_op(t, op_external_clock, t_old, t_new);
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aspeed_timer_ctrl_op(t, op_overflow_interrupt, t_old, t_new);
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aspeed_timer_ctrl_op(t, op_pulse_enable, t_old, t_new);
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/* If we are enabling, do so last */
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if (!(t_old & enable_mask) && (t_new & enable_mask)) {
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aspeed_timer_ctrl_enable(t, true);
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}
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}
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s->ctrl = reg;
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}
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static void aspeed_timer_set_ctrl2(AspeedTimerCtrlState *s, uint32_t value)
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{
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trace_aspeed_timer_set_ctrl2(value);
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}
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static void aspeed_timer_write(void *opaque, hwaddr offset, uint64_t value,
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unsigned size)
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{
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const uint32_t tv = (uint32_t)(value & 0xFFFFFFFF);
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const int reg = (offset & 0xf) / 4;
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AspeedTimerCtrlState *s = opaque;
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switch (offset) {
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/* Control Registers */
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case 0x30:
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aspeed_timer_set_ctrl(s, tv);
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break;
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case 0x34:
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aspeed_timer_set_ctrl2(s, tv);
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break;
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/* Timer Registers */
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case 0x00 ... 0x2c:
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aspeed_timer_set_value(s, (offset >> TIMER_NR_REGS), reg, tv);
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break;
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case 0x40 ... 0x8c:
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aspeed_timer_set_value(s, (offset >> TIMER_NR_REGS) - 1, reg, tv);
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break;
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/* Illegal */
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case 0x38:
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case 0x3C:
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default:
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qemu_log_mask(LOG_GUEST_ERROR, "%s: Bad offset 0x%" HWADDR_PRIx "\n",
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__func__, offset);
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break;
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}
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}
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static const MemoryRegionOps aspeed_timer_ops = {
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.read = aspeed_timer_read,
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.write = aspeed_timer_write,
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.endianness = DEVICE_LITTLE_ENDIAN,
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.valid.min_access_size = 4,
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.valid.max_access_size = 4,
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.valid.unaligned = false,
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};
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static void aspeed_init_one_timer(AspeedTimerCtrlState *s, uint8_t id)
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{
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AspeedTimer *t = &s->timers[id];
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t->id = id;
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timer_init_ns(&t->timer, QEMU_CLOCK_VIRTUAL, aspeed_timer_expire, t);
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}
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static void aspeed_timer_realize(DeviceState *dev, Error **errp)
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{
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int i;
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SysBusDevice *sbd = SYS_BUS_DEVICE(dev);
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AspeedTimerCtrlState *s = ASPEED_TIMER(dev);
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Object *obj;
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Error *err = NULL;
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obj = object_property_get_link(OBJECT(dev), "scu", &err);
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if (!obj) {
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error_propagate_prepend(errp, err, "required link 'scu' not found: ");
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return;
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}
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s->scu = ASPEED_SCU(obj);
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for (i = 0; i < ASPEED_TIMER_NR_TIMERS; i++) {
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aspeed_init_one_timer(s, i);
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sysbus_init_irq(sbd, &s->timers[i].irq);
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}
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memory_region_init_io(&s->iomem, OBJECT(s), &aspeed_timer_ops, s,
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TYPE_ASPEED_TIMER, 0x1000);
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sysbus_init_mmio(sbd, &s->iomem);
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}
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static void aspeed_timer_reset(DeviceState *dev)
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{
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int i;
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AspeedTimerCtrlState *s = ASPEED_TIMER(dev);
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|
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for (i = 0; i < ASPEED_TIMER_NR_TIMERS; i++) {
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AspeedTimer *t = &s->timers[i];
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/* Explicitly call helpers to avoid any conditional behaviour through
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* aspeed_timer_set_ctrl().
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*/
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aspeed_timer_ctrl_enable(t, false);
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aspeed_timer_ctrl_external_clock(t, TIMER_CLOCK_USE_APB);
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aspeed_timer_ctrl_overflow_interrupt(t, false);
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aspeed_timer_ctrl_pulse_enable(t, false);
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t->level = 0;
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t->reload = 0;
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t->match[0] = 0;
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t->match[1] = 0;
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}
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s->ctrl = 0;
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s->ctrl2 = 0;
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}
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static const VMStateDescription vmstate_aspeed_timer = {
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.name = "aspeed.timer",
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.version_id = 2,
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.minimum_version_id = 2,
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.fields = (VMStateField[]) {
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VMSTATE_UINT8(id, AspeedTimer),
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VMSTATE_INT32(level, AspeedTimer),
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VMSTATE_TIMER(timer, AspeedTimer),
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VMSTATE_UINT32(reload, AspeedTimer),
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VMSTATE_UINT32_ARRAY(match, AspeedTimer, 2),
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VMSTATE_END_OF_LIST()
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}
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};
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|
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static const VMStateDescription vmstate_aspeed_timer_state = {
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.name = "aspeed.timerctrl",
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|
.version_id = 1,
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|
.minimum_version_id = 1,
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|
.fields = (VMStateField[]) {
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VMSTATE_UINT32(ctrl, AspeedTimerCtrlState),
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VMSTATE_UINT32(ctrl2, AspeedTimerCtrlState),
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VMSTATE_STRUCT_ARRAY(timers, AspeedTimerCtrlState,
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|
ASPEED_TIMER_NR_TIMERS, 1, vmstate_aspeed_timer,
|
|
AspeedTimer),
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|
VMSTATE_END_OF_LIST()
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|
}
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|
};
|
|
|
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static void timer_class_init(ObjectClass *klass, void *data)
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|
{
|
|
DeviceClass *dc = DEVICE_CLASS(klass);
|
|
|
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dc->realize = aspeed_timer_realize;
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|
dc->reset = aspeed_timer_reset;
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dc->desc = "ASPEED Timer";
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|
dc->vmsd = &vmstate_aspeed_timer_state;
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}
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|
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static const TypeInfo aspeed_timer_info = {
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.name = TYPE_ASPEED_TIMER,
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|
.parent = TYPE_SYS_BUS_DEVICE,
|
|
.instance_size = sizeof(AspeedTimerCtrlState),
|
|
.class_init = timer_class_init,
|
|
};
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|
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static void aspeed_timer_register_types(void)
|
|
{
|
|
type_register_static(&aspeed_timer_info);
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|
}
|
|
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|
type_init(aspeed_timer_register_types)
|