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![Jessica Clarke](/assets/img/avatar_default.png)
Unlike amd64's, this RTC is implemented entirely in userspace. This is the same RTC as is provided by QEMU's virt machine. Reviewed by: jhb MFC after: 2 weeks Obtained from: CheriBSD
280 lines
6 KiB
C
280 lines
6 KiB
C
/*-
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* SPDX-License-Identifier: BSD-2-Clause
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*
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* Copyright (c) 2024 Jessica Clarke <jrtc27@FreeBSD.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/param.h>
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#include <assert.h>
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#include <limits.h>
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#include <pthread.h>
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#include <stdlib.h>
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#include <time.h>
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#include "config.h"
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#include "mevent.h"
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#include "rtc_pl031.h"
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#define RTCDR 0x000
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#define RTCMR 0x004
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#define RTCLR 0x008
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#define RTCCR 0x00C
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#define RTCIMSC 0x010
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#define RTCRIS 0x014
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#define RTCMIS 0x018
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#define RTCICR 0x01C
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#define RTCPeriphID0 0xFE0
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#define RTCPeriphID1 0xFE4
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#define RTCPeriphID2 0xFE8
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#define RTCPeriphID3 0xFEC
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#define _RTCPeriphID_VAL 0x00141031
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#define RTCPeriphID_VAL(_n) ((_RTCPeriphID_VAL >> (8 * (_n))) & 0xff)
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#define RTCCellID0 0xFF0
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#define RTCCellID1 0xFF4
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#define RTCCellID2 0xFF8
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#define RTCCellID3 0xFFC
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#define _RTCCellID_VAL 0xb105f00d
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#define RTCCellID_VAL(_n) ((_RTCCellID_VAL >> (8 * (_n))) & 0xff)
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struct rtc_pl031_softc {
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pthread_mutex_t mtx;
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time_t last_tick;
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uint32_t dr;
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uint32_t mr;
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uint32_t lr;
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uint8_t imsc;
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uint8_t ris;
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uint8_t prev_mis;
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struct mevent *mevp;
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void *arg;
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rtc_pl031_intr_func_t intr_assert;
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rtc_pl031_intr_func_t intr_deassert;
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};
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static void rtc_pl031_callback(int fd, enum ev_type type, void *param);
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/*
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* Returns the current RTC time as number of seconds since 00:00:00 Jan 1, 1970
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*/
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static time_t
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rtc_pl031_time(void)
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{
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struct tm tm;
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time_t t;
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time(&t);
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if (get_config_bool_default("rtc.use_localtime", false)) {
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localtime_r(&t, &tm);
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t = timegm(&tm);
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}
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return (t);
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}
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static void
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rtc_pl031_update_mis(struct rtc_pl031_softc *sc)
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{
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uint8_t mis;
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mis = sc->ris & sc->imsc;
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if (mis == sc->prev_mis)
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return;
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sc->prev_mis = mis;
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if (mis)
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(*sc->intr_assert)(sc->arg);
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else
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(*sc->intr_deassert)(sc->arg);
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}
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static uint64_t
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rtc_pl031_next_match_ticks(struct rtc_pl031_softc *sc)
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{
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uint32_t ticks;
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ticks = sc->mr - sc->dr;
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if (ticks == 0)
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return ((uint64_t)1 << 32);
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return (ticks);
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}
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static int
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rtc_pl031_next_timer_msecs(struct rtc_pl031_softc *sc)
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{
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uint64_t ticks;
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ticks = rtc_pl031_next_match_ticks(sc);
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return (MIN(ticks * 1000, INT_MAX));
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}
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static void
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rtc_pl031_update_timer(struct rtc_pl031_softc *sc)
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{
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mevent_timer_update(sc->mevp, rtc_pl031_next_timer_msecs(sc));
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}
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static void
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rtc_pl031_tick(struct rtc_pl031_softc *sc, bool from_timer)
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{
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bool match;
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time_t now, ticks;
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now = rtc_pl031_time();
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ticks = now - sc->last_tick;
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match = ticks >= 0 &&
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(uint64_t)ticks >= rtc_pl031_next_match_ticks(sc);
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sc->dr += ticks;
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sc->last_tick = now;
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if (match) {
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sc->ris = 1;
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rtc_pl031_update_mis(sc);
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}
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if (match || from_timer || ticks < 0)
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rtc_pl031_update_timer(sc);
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}
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static void
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rtc_pl031_callback(int fd __unused, enum ev_type type __unused, void *param)
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{
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struct rtc_pl031_softc *sc = param;
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pthread_mutex_lock(&sc->mtx);
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rtc_pl031_tick(sc, true);
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pthread_mutex_unlock(&sc->mtx);
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}
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void
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rtc_pl031_write(struct rtc_pl031_softc *sc, int offset, uint32_t value)
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{
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pthread_mutex_lock(&sc->mtx);
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rtc_pl031_tick(sc, false);
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switch (offset) {
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case RTCMR:
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sc->mr = value;
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rtc_pl031_update_timer(sc);
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break;
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case RTCLR:
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sc->lr = value;
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sc->dr = sc->lr;
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rtc_pl031_update_timer(sc);
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break;
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case RTCIMSC:
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sc->imsc = value & 1;
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rtc_pl031_update_mis(sc);
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break;
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case RTCICR:
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sc->ris &= ~value;
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rtc_pl031_update_mis(sc);
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break;
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default:
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/* Ignore writes to read-only/unassigned/ID registers */
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break;
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}
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pthread_mutex_unlock(&sc->mtx);
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}
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uint32_t
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rtc_pl031_read(struct rtc_pl031_softc *sc, int offset)
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{
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uint32_t reg;
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pthread_mutex_lock(&sc->mtx);
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rtc_pl031_tick(sc, false);
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switch (offset) {
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case RTCDR:
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reg = sc->dr;
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break;
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case RTCMR:
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reg = sc->mr;
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break;
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case RTCLR:
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reg = sc->lr;
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break;
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case RTCCR:
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/* RTC enabled from reset */
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reg = 1;
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break;
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case RTCIMSC:
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reg = sc->imsc;
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break;
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case RTCRIS:
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reg = sc->ris;
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break;
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case RTCMIS:
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reg = sc->ris & sc->imsc;
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break;
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case RTCPeriphID0:
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case RTCPeriphID1:
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case RTCPeriphID2:
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case RTCPeriphID3:
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reg = RTCPeriphID_VAL(offset - RTCPeriphID0);
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break;
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case RTCCellID0:
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case RTCCellID1:
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case RTCCellID2:
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case RTCCellID3:
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reg = RTCCellID_VAL(offset - RTCCellID0);
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break;
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default:
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/* Return 0 in reads from unasigned registers */
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reg = 0;
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break;
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}
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pthread_mutex_unlock(&sc->mtx);
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return (reg);
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}
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struct rtc_pl031_softc *
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rtc_pl031_init(rtc_pl031_intr_func_t intr_assert,
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rtc_pl031_intr_func_t intr_deassert, void *arg)
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{
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struct rtc_pl031_softc *sc;
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time_t now;
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sc = calloc(1, sizeof(struct rtc_pl031_softc));
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pthread_mutex_init(&sc->mtx, NULL);
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now = rtc_pl031_time();
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sc->dr = now;
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sc->last_tick = now;
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sc->arg = arg;
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sc->intr_assert = intr_assert;
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sc->intr_deassert = intr_deassert;
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sc->mevp = mevent_add(rtc_pl031_next_timer_msecs(sc), EVF_TIMER,
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rtc_pl031_callback, sc);
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return (sc);
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}
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