/* $OpenBSD: i8253.h,v 1.11 2025/06/12 21:04:37 dv Exp $ */
/*
 * Copyright (c) 2016 Mike Larkin <mlarkin@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

/*
 * Emulated i8253 PIT (counter)
 */
#define TIMER_BASE      0x40    /* 8253 timer 0 */
#define TIMER_CTRL      0x43    /* 8253 timer control */
#define NS_PER_TICK     (1000000000 / TIMER_FREQ)
#define TIMER_RB_COUNT  0x20    /* read back count value */
#define TIMER_RB_STATUS 0x10    /* read back status */
#define TIMER_RB_C0     0x2     /* read back channel 0 */
#define TIMER_RB_C1     0x4     /* read back channel 1 */
#define TIMER_RB_C2     0x8     /* read back channel 1 */
#define PCKBC_AUX       0x61    /* PC keyboard aux port for i8253 misc access */

/* i8253 registers */
struct i8253_channel {
        struct timespec ts;     /* timer start time */
        uint16_t start;         /* starting value */
        uint16_t olatch;        /* output latch */
        uint16_t ilatch;        /* input latch */
        uint8_t last_r;         /* last read byte (MSB/LSB) */
        uint8_t last_w;         /* last written byte (MSB/LSB) */
        uint8_t mode;           /* counter mode */
        uint8_t rbs;            /* channel is in readback status mode */
        struct event timer;     /* timer event for this counter */
        uint32_t vm_id;         /* owning VM id */
        int in_use;             /* denotes if this counter was ever used */
        uint8_t state;          /* 0 if channel is counting, 1 if fired */
};

void i8253_init(uint32_t);
void i8253_reset(uint8_t);
void i8253_fire(int, short, void *);
uint8_t vcpu_exit_i8253(struct vm_run_params *);
uint8_t vcpu_exit_i8253_misc(struct vm_run_params *);
void i8253_do_readback(uint32_t);
void i8253_stop(void);
void i8253_start(void);