/*
* AVR 16-bit timer
*
* Copyright (c) 2018 University of Kent
* Author: Ed Robbins
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library 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. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see
* <http://www.gnu.org/licenses/lgpl-2.1.html>
*/
/*
* Driver for 16 bit timers on 8 bit AVR devices.
* Note:
* ATmega640/V-1280/V-1281/V-2560/V-2561/V timers 1, 3, 4 and 5 are 16 bit
*/
/*
* XXX TODO: Power Reduction Register support
* prescaler pause support
* PWM modes, GPIO, output capture pins, input compare pin
*/
#include "qemu/osdep.h"
#include "qapi/error.h"
#include "qemu/log.h"
#include "hw/irq.h"
#include "hw/qdev-properties.h"
#include "hw/timer/avr_timer16.h"
#include "trace.h"
/* Register offsets */
#define T16_CRA 0x0
#define T16_CRB 0x1
#define T16_CRC 0x2
#define T16_CNTL 0x4
#define T16_CNTH 0x5
#define T16_ICRL 0x6
#define T16_ICRH 0x7
#define T16_OCRAL 0x8
#define T16_OCRAH 0x9
#define T16_OCRBL 0xa
#define T16_OCRBH 0xb
#define T16_OCRCL 0xc
#define T16_OCRCH 0xd
/* Field masks */
#define T16_CRA_WGM01 0x3
#define T16_CRA_COMC 0xc
#define T16_CRA_COMB 0x30
#define T16_CRA_COMA 0xc0
#define T16_CRA_OC_CONF \
(T16_CRA_COMA | T16_CRA_COMB | T16_CRA_COMC)
#define T16_CRB_CS 0x7
#define T16_CRB_WGM23 0x18
#define T16_CRB_ICES 0x40
#define T16_CRB_ICNC 0x80
#define T16_CRC_FOCC 0x20
#define T16_CRC_FOCB 0x40
#define T16_CRC_FOCA 0x80
/* Fields masks both TIMSK and TIFR (interrupt mask/flag registers) */
#define T16_INT_TOV 0x1 /* Timer overflow */
#define T16_INT_OCA 0x2 /* Output compare A */
#define T16_INT_OCB 0x4 /* Output compare B */
#define T16_INT_OCC 0x8 /* Output compare C */
#define T16_INT_IC 0x20 /* Input capture */
/* Clock source values */
#define T16_CLKSRC_STOPPED 0
#define T16_CLKSRC_DIV1 1
#define T16_CLKSRC_DIV8 2
#define T16_CLKSRC_DIV64 3
#define T16_CLKSRC_DIV256 4
#define T16_CLKSRC_DIV1024 5
#define T16_CLKSRC_EXT_FALLING 6
#define T16_CLKSRC_EXT_RISING 7
/* Timer mode values (not including PWM modes) */
#define T16_MODE_NORMAL 0
#define T16_MODE_CTC_OCRA 4
#define T16_MODE_CTC_ICR 12
/* Accessors */
#define CLKSRC(t16) (t16->crb & T16_CRB_CS)
#define MODE(t16) (((t16->crb & T16_CRB_WGM23) >> 1) | \
(t16->cra & T16_CRA_WGM01))
#define CNT(t16) VAL16(t16->cntl, t16->cnth)
#define OCRA(t16) VAL16(t16->ocral, t16->ocrah)
#define OCRB(t16) VAL16(t16->ocrbl, t16->ocrbh)
#define OCRC(t16) VAL16(t16->ocrcl, t16->ocrch)
#define ICR(t16) VAL16(t16->icrl, t16->icrh)
/* Helper macros */
#define VAL16(l, h) ((h << 8) | l)
#define DB_PRINT(fmt, args...) /* Nothing */
static inline int64_t avr_timer16_ns_to_ticks(AVRTimer16State *t16, int64_t t)
{
if (t16->period_ns == 0) {
return 0;
}
return t / t16->period_ns;
}
static void avr_timer16_update_cnt(AVRTimer16State *t16)
{
uint16_t cnt;
cnt = avr_timer16_ns_to_ticks(t16, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) -
t16->reset_time_ns);
t16->cntl = (uint8_t)(cnt & 0xff);
t16->cnth = (uint8_t)((cnt & 0xff00) >> 8);
}
static inline void avr_timer16_recalc_reset_time(AVRTimer16State *t16)
{
t16->reset_time_ns = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) -
CNT(t16) * t16->period_ns;
}
static void avr_timer16_clock_reset(AVRTimer16State *t16)
{
t16->cntl = 0;
t16->cnth = 0;
t16->reset_time_ns = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
}
static void avr_timer16_clksrc_update(AVRTimer16State *t16)
{
uint16_t divider = 0;
switch (CLKSRC(t16)) {
case T16_CLKSRC_EXT_FALLING:
case T16_CLKSRC_EXT_RISING:
qemu_log_mask(LOG_UNIMP, "%s: external clock source unsupported\n",
__func__);
break;
case T16_CLKSRC_STOPPED:
break;
case T16_CLKSRC_DIV1:
divider = 1;
break;
case T16_CLKSRC_DIV8:
divider = 8;
break;
case T16_CLKSRC_DIV64:
divider = 64;
break;
case T16_CLKSRC_DIV256:
divider = 256;
break;
case T16_CLKSRC_DIV1024:
divider = 1024;
break;
default:
break;
}
if (divider) {
t16->freq_hz = t16->cpu_freq_hz / divider;
t16->period_ns = NANOSECONDS_PER_SECOND / t16->freq_hz;
trace_avr_timer16_clksrc_update(t16->freq_hz, t16->period_ns,
(uint64_t)(1e6 / t16->freq_hz));
}
}
static void avr_timer16_set_alarm(AVRTimer16State *t16)
{
if (CLKSRC(t16) == T16_CLKSRC_EXT_FALLING ||
CLKSRC(t16) == T16_CLKSRC_EXT_RISING ||
CLKSRC(t16) == T16_CLKSRC_STOPPED) {
/* Timer is disabled or set to external clock source (unsupported) */
return;
}
uint64_t alarm_offset = 0xffff;
enum NextInterrupt next_interrupt = OVERFLOW;
switch (MODE(t16)) {
case T16_MODE_NORMAL:
/* Normal mode */
if (OCRA(t16) < alarm_offset && OCRA(t16) > CNT(t16) &&
(t16->imsk & T16_INT_OCA)) {
alarm_offset = OCRA(t16);
next_interrupt = COMPA;
}
break;
case T16_MODE_CTC_OCRA:
/* CTC mode, top = ocra */
if (OCRA(t16) < alarm_offset && OCRA(t16) > CNT(t16)) {
alarm_offset = OCRA(t16);
next_interrupt = COMPA;
}
break;
case T16_MODE_CTC_ICR:
/* CTC mode, top = icr */
if (ICR(t16) < alarm_offset && ICR(t16) > CNT(t16)) {
alarm_offset = ICR(t16);
next_interrupt = CAPT;
}
if (OCRA(t16) < alarm_offset && OCRA(t16) > CNT(t16) &&
(t16->imsk & T16_INT_OCA)) {
alarm_offset = OCRA(t16);
next_interrupt = COMPA;
}
break;
default:
qemu_log_mask(LOG_UNIMP, "%s: pwm modes are unsupported\n",
__func__);
return;
}
if (OCRB(t16) < alarm_offset && OCRB(t16) > CNT(t16) &&
(t16->imsk & T16_INT_OCB)) {
alarm_offset = OCRB(t16);
next_interrupt = COMPB;
}
if (OCRC(t16) < alarm_offset && OCRB(t16) > CNT(t16) &&
(t16->imsk & T16_INT_OCC)) {
alarm_offset = OCRB(t16);
next_interrupt = COMPC;
}
alarm_offset -= CNT(t16);
t16->next_interrupt = next_interrupt;
uint64_t alarm_ns =
t16->reset_time_ns + ((CNT(t16) + alarm_offset) * t16->period_ns);
timer_mod(t16->timer, alarm_ns);
trace_avr_timer16_next_alarm(alarm_offset * t16->period_ns);
}
static void avr_timer16_interrupt(void *opaque)
{
AVRTimer16State *t16 = opaque;
uint8_t mode = MODE(t16);
avr_timer16_update_cnt(t16);
if (CLKSRC(t16) == T16_CLKSRC_EXT_FALLING ||
CLKSRC(t16) == T16_CLKSRC_EXT_RISING ||
CLKSRC(t16) == T16_CLKSRC_STOPPED) {
/* Timer is disabled or set to external clock source (unsupported) */
return;
}
trace_avr_timer16_interrupt_count(CNT(t16));
/* Counter overflow */
if (t16->next_interrupt == OVERFLOW) {
trace_avr_timer16_interrupt_overflow("counter 0xffff");
avr_timer16_clock_reset(t16);
if (t16->imsk & T16_INT_TOV) {
t16->ifr |= T16_INT_TOV;
qemu_set_irq(t16->ovf_irq, 1);
}
}
/* Check for ocra overflow in CTC mode */
if (mode == T16_MODE_CTC_OCRA && t16->next_interrupt == COMPA) {
trace_avr_timer16_interrupt_overflow("CTC OCRA");
avr_timer16_clock_reset(t16);
}
/* Check for icr overflow in CTC mode */
if (mode == T16_MODE_CTC_ICR && t16->next_interrupt == CAPT) {
trace_avr_timer16_interrupt_overflow("CTC ICR");
avr_timer16_clock_reset(t16);
if (t16->imsk & T16_INT_IC) {
t16->ifr |= T16_INT_IC;
qemu_set_irq(t16->capt_irq, 1);
}
}
/* Check for output compare interrupts */
if (t16->imsk & T16_INT_OCA && t16->next_interrupt == COMPA) {
t16->ifr |= T16_INT_OCA;
qemu_set_irq(t16->compa_irq, 1);
}
if (t16->imsk & T16_INT_OCB && t16->next_interrupt == COMPB) {
t16->ifr |= T16_INT_OCB;
qemu_set_irq(t16->compb_irq, 1);
}
if (t16->imsk & T16_INT_OCC && t16->next_interrupt == COMPC) {
t16->ifr |= T16_INT_OCC;
qemu_set_irq(t16->compc_irq, 1);
}
avr_timer16_set_alarm(t16);
}
static void avr_timer16_reset(DeviceState *dev)
{
AVRTimer16State *t16 = AVR_TIMER16(dev);
avr_timer16_clock_reset(t16);
avr_timer16_clksrc_update(t16);
avr_timer16_set_alarm(t16);
qemu_set_irq(t16->capt_irq, 0);
qemu_set_irq(t16->compa_irq, 0);
qemu_set_irq(t16->compb_irq, 0);
qemu_set_irq(t16->compc_irq, 0);
qemu_set_irq(t16->ovf_irq, 0);
}
static uint64_t avr_timer16_read(void *opaque, hwaddr offset, unsigned size)
{
assert(size == 1);
AVRTimer16State *t16 = opaque;
uint8_t retval = 0;
switch (offset) {
case T16_CRA:
retval = t16->cra;
break;
case T16_CRB:
retval = t16->crb;
break;
case T16_CRC:
retval = t16->crc;
break;
case T16_CNTL:
avr_timer16_update_cnt(t16);
t16->rtmp = t16->cnth;
retval = t16->cntl;
break;
case T16_CNTH:
retval = t16->rtmp;
break;
case T16_ICRL:
/*
* The timer copies cnt to icr when the input capture pin changes
* state or when the analog comparator has a match. We don't
* emulate this behaviour. We do support it's use for defining a
* TOP value in T16_MODE_CTC_ICR
*/
t16->rtmp = t16->icrh;
retval = t16->icrl;
break;
case T16_ICRH:
retval = t16->rtmp;
break;
case T16_OCRAL:
retval = t16->ocral;
break;
case T16_OCRAH:
retval = t16->ocrah;
break;
case T16_OCRBL:
retval = t16->ocrbl;
break;
case T16_OCRBH:
retval = t16->ocrbh;
break;
case T16_OCRCL:
retval = t16->ocrcl;
break;
case T16_OCRCH:
retval = t16->ocrch;
break;
default:
break;
}
trace_avr_timer16_read(offset, retval);
return (uint64_t)retval;
}
static void avr_timer16_write(void *opaque, hwaddr offset,
uint64_t val64, unsigned size)
{
assert(size == 1);
AVRTimer16State *t16 = opaque;
uint8_t val8 = (uint8_t)val64;
uint8_t prev_clk_src = CLKSRC(t16);
trace_avr_timer16_write(offset, val8);
switch (offset) {
case T16_CRA:
t16->cra = val8;
if (t16->cra & T16_CRA_OC_CONF) {
qemu_log_mask(LOG_UNIMP, "%s: output compare pins unsupported\n",
__func__);
}
break;
case T16_CRB:
t16->crb = val8;
if (t16->crb & T16_CRB_ICNC) {
qemu_log_mask(LOG_UNIMP,
"%s: input capture noise canceller unsupported\n",
__func__);
}
if (t16->crb & T16_CRB_ICES) {
qemu_log_mask(LOG_UNIMP, "%s: input capture unsupported\n",
__func__);
}
if (CLKSRC(t16) != prev_clk_src) {
avr_timer16_clksrc_update(t16);
if (prev_clk_src == T16_CLKSRC_STOPPED) {
t16->reset_time_ns = qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL);
}
}
break;
case T16_CRC:
t16->crc = val8;
qemu_log_mask(LOG_UNIMP, "%s: output compare pins unsupported\n",
__func__);
break;
case T16_CNTL:
/*
* CNT is the 16-bit counter value, it must be read/written via
* a temporary register (rtmp) to make the read/write atomic.
*/
/* ICR also has this behaviour, and shares rtmp */
/*
* Writing CNT blocks compare matches for one clock cycle.
* Writing CNT to TOP or to an OCR value (if in use) will
* skip the relevant interrupt
*/
t16->cntl = val8;
t16->cnth = t16->rtmp;
avr_timer16_recalc_reset_time(t16);
break;
case T16_CNTH:
t16->rtmp = val8;
break;
case T16_ICRL:
/* ICR can only be written in mode T16_MODE_CTC_ICR */
if (MODE(t16) == T16_MODE_CTC_ICR) {
t16->icrl = val8;
t16->icrh = t16->rtmp;
}
break;
case T16_ICRH:
if (MODE(t16) == T16_MODE_CTC_ICR) {
t16->rtmp = val8;
}
break;
case T16_OCRAL:
/*
* OCRn cause the relevant output compare flag to be raised, and
* trigger an interrupt, when CNT is equal to the value here
*/
t16->ocral = val8;
break;
case T16_OCRAH:
t16->ocrah = val8;
break;
case T16_OCRBL:
t16->ocrbl = val8;
break;
case T16_OCRBH:
t16->ocrbh = val8;
break;
case T16_OCRCL:
t16->ocrcl = val8;
break;
case T16_OCRCH:
t16->ocrch = val8;
break;
default:
break;
}
avr_timer16_set_alarm(t16);
}
static uint64_t avr_timer16_imsk_read(void *opaque,
hwaddr offset,
unsigned size)
{
assert(size == 1);
AVRTimer16State *t16 = opaque;
trace_avr_timer16_read_imsk(offset ? 0 : t16->imsk);
if (offset != 0) {
return 0;
}
return t16->imsk;
}
static void avr_timer16_imsk_write(void *opaque, hwaddr offset,
uint64_t val64, unsigned size)
{
assert(size == 1);
AVRTimer16State *t16 = opaque;
trace_avr_timer16_write_imsk(val64);
if (offset != 0) {
return;
}
t16->imsk = (uint8_t)val64;
}
static uint64_t avr_timer16_ifr_read(void *opaque,
hwaddr offset,
unsigned size)
{
assert(size == 1);
AVRTimer16State *t16 = opaque;
trace_avr_timer16_read_ifr(offset ? 0 : t16->ifr);
if (offset != 0) {
return 0;
}
return t16->ifr;
}
static void avr_timer16_ifr_write(void *opaque, hwaddr offset,
uint64_t val64, unsigned size)
{
assert(size == 1);
AVRTimer16State *t16 = opaque;
trace_avr_timer16_write_imsk(val64);
if (offset != 0) {
return;
}
t16->ifr = (uint8_t)val64;
}
static const MemoryRegionOps avr_timer16_ops = {
.read = avr_timer16_read,
.write = avr_timer16_write,
.endianness = DEVICE_NATIVE_ENDIAN,
.impl = {.max_access_size = 1}
};
static const MemoryRegionOps avr_timer16_imsk_ops = {
.read = avr_timer16_imsk_read,
.write = avr_timer16_imsk_write,
.endianness = DEVICE_NATIVE_ENDIAN,
.impl = {.max_access_size = 1}
};
static const MemoryRegionOps avr_timer16_ifr_ops = {
.read = avr_timer16_ifr_read,
.write = avr_timer16_ifr_write,
.endianness = DEVICE_NATIVE_ENDIAN,
.impl = {.max_access_size = 1}
};
static Property avr_timer16_properties[] = {
DEFINE_PROP_UINT8("id", struct AVRTimer16State, id, 0),
DEFINE_PROP_UINT64("cpu-frequency-hz", struct AVRTimer16State,
cpu_freq_hz, 0),
DEFINE_PROP_END_OF_LIST(),
};
static void avr_timer16_pr(void *opaque, int irq, int level)
{
AVRTimer16State *s = AVR_TIMER16(opaque);
s->enabled = !level;
if (!s->enabled) {
avr_timer16_reset(DEVICE(s));
}
}
static void avr_timer16_init(Object *obj)
{
AVRTimer16State *s = AVR_TIMER16(obj);
sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->capt_irq);
sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->compa_irq);
sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->compb_irq);
sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->compc_irq);
sysbus_init_irq(SYS_BUS_DEVICE(obj), &s->ovf_irq);
memory_region_init_io(&s->iomem, obj, &avr_timer16_ops,
s, "avr-timer16", 0xe);
memory_region_init_io(&s->imsk_iomem, obj, &avr_timer16_imsk_ops,
s, "avr-timer16-intmask", 0x1);
memory_region_init_io(&s->ifr_iomem, obj, &avr_timer16_ifr_ops,
s, "avr-timer16-intflag", 0x1);
sysbus_init_mmio(SYS_BUS_DEVICE(obj), &s->iomem);
sysbus_init_mmio(SYS_BUS_DEVICE(obj), &s->imsk_iomem);
sysbus_init_mmio(SYS_BUS_DEVICE(obj), &s->ifr_iomem);
qdev_init_gpio_in(DEVICE(s), avr_timer16_pr, 1);
}
static void avr_timer16_realize(DeviceState *dev, Error **errp)
{
AVRTimer16State *s = AVR_TIMER16(dev);
if (s->cpu_freq_hz == 0) {
error_setg(errp, "AVR timer16: cpu-frequency-hz property must be set");
return;
}
s->timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, avr_timer16_interrupt, s);
s->enabled = true;
}
static void avr_timer16_class_init(ObjectClass *klass, void *data)
{
DeviceClass *dc = DEVICE_CLASS(klass);
dc->reset = avr_timer16_reset;
dc->realize = avr_timer16_realize;
device_class_set_props(dc, avr_timer16_properties);
}
static const TypeInfo avr_timer16_info = {
.name = TYPE_AVR_TIMER16,
.parent = TYPE_SYS_BUS_DEVICE,
.instance_size = sizeof(AVRTimer16State),
.instance_init = avr_timer16_init,
.class_init = avr_timer16_class_init,
};
static void avr_timer16_register_types(void)
{
type_register_static(&avr_timer16_info);
}
type_init(avr_timer16_register_types)
