/*
 * QEMU model of the Xilinx timer block.
 *
 * Copyright (c) 2009 Edgar E. Iglesias.
 *
 * DS573: https://docs.amd.com/v/u/en-US/xps_timer
 * LogiCORE IP XPS Timer/Counter (v1.02a)
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include "qemu/osdep.h"
#include "qapi/error.h"
#include "hw/sysbus.h"
#include "hw/irq.h"
#include "hw/ptimer.h"
#include "hw/qdev-properties.h"
#include "hw/qdev-properties-system.h"
#include "qemu/log.h"
#include "qemu/module.h"
#include "qom/object.h"

#define D(x)

#define R_TCSR     0
#define R_TLR      1
#define R_TCR      2
#define R_MAX      4

#define TCSR_MDT        (1<<0)
#define TCSR_UDT        (1<<1)
#define TCSR_GENT       (1<<2)
#define TCSR_CAPT       (1<<3)
#define TCSR_ARHT       (1<<4)
#define TCSR_LOAD       (1<<5)
#define TCSR_ENIT       (1<<6)
#define TCSR_ENT        (1<<7)
#define TCSR_TINT       (1<<8)
#define TCSR_PWMA       (1<<9)
#define TCSR_ENALL      (1<<10)

struct xlx_timer
{
    ptimer_state *ptimer;
    void *parent;
    int nr; /* for debug.  */

    unsigned long timer_div;

    uint32_t regs[R_MAX];
};

#define TYPE_XILINX_TIMER "xlnx.xps-timer"
typedef struct XpsTimerState XpsTimerState;
DECLARE_INSTANCE_CHECKER(XpsTimerState, XILINX_TIMER, TYPE_XILINX_TIMER)

struct XpsTimerState
{
    SysBusDevice parent_obj;

    EndianMode model_endianness;
    MemoryRegion mmio;
    qemu_irq irq;
    uint8_t one_timer_only;
    uint32_t freq_hz;
    struct xlx_timer *timers;
};

static inline unsigned int num_timers(XpsTimerState *t)
{
    return 2 - t->one_timer_only;
}

static inline unsigned int timer_from_addr(hwaddr addr)
{
    /* Timers get a 4x32bit control reg area each.  */
    return addr >> 2;
}

static void timer_update_irq(XpsTimerState *t)
{
    unsigned int i, irq = 0;
    uint32_t csr;

    for (i = 0; i < num_timers(t); i++) {
        csr = t->timers[i].regs[R_TCSR];
        irq |= (csr & TCSR_TINT) && (csr & TCSR_ENIT);
    }

    /* All timers within the same slave share a single IRQ line.  */
    qemu_set_irq(t->irq, !!irq);
}

static uint64_t
timer_read(void *opaque, hwaddr addr, unsigned int size)
{
    XpsTimerState *t = opaque;
    struct xlx_timer *xt;
    uint32_t r = 0;
    unsigned int timer;

    addr >>= 2;
    timer = timer_from_addr(addr);
    xt = &t->timers[timer];
    /* Further decoding to address a specific timers reg.  */
    addr &= 0x3;
    switch (addr)
    {
        case R_TCR:
                r = ptimer_get_count(xt->ptimer);
                if (!(xt->regs[R_TCSR] & TCSR_UDT))
                    r = ~r;
                D(qemu_log("xlx_timer t=%d read counter=%x udt=%d\n",
                         timer, r, xt->regs[R_TCSR] & TCSR_UDT));
            break;
        default:
            if (addr < ARRAY_SIZE(xt->regs))
                r = xt->regs[addr];
            break;

    }
    D(fprintf(stderr, "%s timer=%d %x=%x\n", __func__, timer, addr * 4, r));
    return r;
}

/* Must be called inside ptimer transaction block */
static void timer_enable(struct xlx_timer *xt)
{
    uint64_t count;

    D(fprintf(stderr, "%s timer=%d down=%d\n", __func__,
              xt->nr, xt->regs[R_TCSR] & TCSR_UDT));

    ptimer_stop(xt->ptimer);

    if (xt->regs[R_TCSR] & TCSR_UDT)
        count = xt->regs[R_TLR];
    else
        count = ~0 - xt->regs[R_TLR];
    ptimer_set_limit(xt->ptimer, count, 1);
    ptimer_run(xt->ptimer, 1);
}

static void
timer_write(void *opaque, hwaddr addr,
            uint64_t val64, unsigned int size)
{
    XpsTimerState *t = opaque;
    struct xlx_timer *xt;
    unsigned int timer;
    uint32_t value = val64;

    addr >>= 2;
    timer = timer_from_addr(addr);
    xt = &t->timers[timer];
    D(fprintf(stderr, "%s addr=%x val=%x (timer=%d off=%d)\n",
             __func__, addr * 4, value, timer, addr & 3));
    /* Further decoding to address a specific timers reg.  */
    addr &= 3;
    switch (addr) 
    {
        case R_TCSR:
            if (value & TCSR_TINT)
                value &= ~TCSR_TINT;

            xt->regs[addr] = value & 0x7ff;
            if (value & TCSR_ENT) {
                ptimer_transaction_begin(xt->ptimer);
                timer_enable(xt);
                ptimer_transaction_commit(xt->ptimer);
            }
            break;
 
        default:
            if (addr < ARRAY_SIZE(xt->regs))
                xt->regs[addr] = value;
            break;
    }
    timer_update_irq(t);
}

static const MemoryRegionOps timer_ops[2] = {
    [0 ... 1] = {
        .read = timer_read,
        .write = timer_write,
        .impl = {
            .min_access_size = 4,
            .max_access_size = 4,
        },
        .valid = {
            .min_access_size = 4,
            .max_access_size = 4,
        },
    },
    [0].endianness = DEVICE_LITTLE_ENDIAN,
    [1].endianness = DEVICE_BIG_ENDIAN,
};

static void timer_hit(void *opaque)
{
    struct xlx_timer *xt = opaque;
    XpsTimerState *t = xt->parent;
    D(fprintf(stderr, "%s %d\n", __func__, xt->nr));
    xt->regs[R_TCSR] |= TCSR_TINT;

    if (xt->regs[R_TCSR] & TCSR_ARHT)
        timer_enable(xt);
    timer_update_irq(t);
}

static void xilinx_timer_realize(DeviceState *dev, Error **errp)
{
    XpsTimerState *t = XILINX_TIMER(dev);
    unsigned int i;

    if (t->model_endianness == ENDIAN_MODE_UNSPECIFIED) {
        error_setg(errp, TYPE_XILINX_TIMER " property 'endianness'"
                         " must be set to 'big' or 'little'");
        return;
    }

    /* Init all the ptimers.  */
    t->timers = g_malloc0(sizeof t->timers[0] * num_timers(t));
    for (i = 0; i < num_timers(t); i++) {
        struct xlx_timer *xt = &t->timers[i];

        xt->parent = t;
        xt->nr = i;
        xt->ptimer = ptimer_init(timer_hit, xt, PTIMER_POLICY_LEGACY);
        ptimer_transaction_begin(xt->ptimer);
        ptimer_set_freq(xt->ptimer, t->freq_hz);
        ptimer_transaction_commit(xt->ptimer);
    }

    memory_region_init_io(&t->mmio, OBJECT(t),
                          &timer_ops[t->model_endianness == ENDIAN_MODE_BIG],
                          t, "xlnx.xps-timer", R_MAX * 4 * num_timers(t));
    sysbus_init_mmio(SYS_BUS_DEVICE(dev), &t->mmio);
}

static void xilinx_timer_init(Object *obj)
{
    XpsTimerState *t = XILINX_TIMER(obj);

    /* All timers share a single irq line.  */
    sysbus_init_irq(SYS_BUS_DEVICE(obj), &t->irq);
}

static const Property xilinx_timer_properties[] = {
    DEFINE_PROP_ENDIAN_NODEFAULT("endianness", XpsTimerState, model_endianness),
    DEFINE_PROP_UINT32("clock-frequency", XpsTimerState, freq_hz, 62 * 1000000),
    DEFINE_PROP_UINT8("one-timer-only", XpsTimerState, one_timer_only, 0),
};

static void xilinx_timer_class_init(ObjectClass *klass, void *data)
{
    DeviceClass *dc = DEVICE_CLASS(klass);

    dc->realize = xilinx_timer_realize;
    device_class_set_props(dc, xilinx_timer_properties);
}

static const TypeInfo xilinx_timer_info = {
    .name          = TYPE_XILINX_TIMER,
    .parent        = TYPE_SYS_BUS_DEVICE,
    .instance_size = sizeof(XpsTimerState),
    .instance_init = xilinx_timer_init,
    .class_init    = xilinx_timer_class_init,
};

static void xilinx_timer_register_types(void)
{
    type_register_static(&xilinx_timer_info);
}

type_init(xilinx_timer_register_types)