#include "hw/qdev.h"
#include "sysemu/char.h"
#include "hw/ppc/spapr.h"
#include "hw/ppc/spapr_vio.h"

#define VTERM_BUFSIZE   16

typedef struct VIOsPAPRVTYDevice {
    VIOsPAPRDevice sdev;
    CharDriverState *chardev;
    uint32_t in, out;
    uint8_t buf[VTERM_BUFSIZE];
} VIOsPAPRVTYDevice;

static int vty_can_receive(void *opaque)
{
    VIOsPAPRVTYDevice *dev = (VIOsPAPRVTYDevice *)opaque;

    return (dev->in - dev->out) < VTERM_BUFSIZE;
}

static void vty_receive(void *opaque, const uint8_t *buf, int size)
{
    VIOsPAPRVTYDevice *dev = (VIOsPAPRVTYDevice *)opaque;
    int i;

    if ((dev->in == dev->out) && size) {
        /* toggle line to simulate edge interrupt */
        qemu_irq_pulse(spapr_vio_qirq(&dev->sdev));
    }
    for (i = 0; i < size; i++) {
        assert((dev->in - dev->out) < VTERM_BUFSIZE);
        dev->buf[dev->in++ % VTERM_BUFSIZE] = buf[i];
    }
}

static int vty_getchars(VIOsPAPRDevice *sdev, uint8_t *buf, int max)
{
    VIOsPAPRVTYDevice *dev = (VIOsPAPRVTYDevice *)sdev;
    int n = 0;

    while ((n < max) && (dev->out != dev->in)) {
        buf[n++] = dev->buf[dev->out++ % VTERM_BUFSIZE];
    }

    return n;
}

void vty_putchars(VIOsPAPRDevice *sdev, uint8_t *buf, int len)
{
    VIOsPAPRVTYDevice *dev = (VIOsPAPRVTYDevice *)sdev;

    /* FIXME: should check the qemu_chr_fe_write() return value */
    qemu_chr_fe_write(dev->chardev, buf, len);
}

static int spapr_vty_init(VIOsPAPRDevice *sdev)
{
    VIOsPAPRVTYDevice *dev = (VIOsPAPRVTYDevice *)sdev;

    if (!dev->chardev) {
        fprintf(stderr, "spapr-vty: Can't create vty without a chardev!\n");
        exit(1);
    }

    qemu_chr_add_handlers(dev->chardev, vty_can_receive,
                          vty_receive, NULL, dev);

    return 0;
}

/* Forward declaration */
static target_ulong h_put_term_char(PowerPCCPU *cpu, sPAPREnvironment *spapr,
                                    target_ulong opcode, target_ulong *args)
{
    target_ulong reg = args[0];
    target_ulong len = args[1];
    target_ulong char0_7 = args[2];
    target_ulong char8_15 = args[3];
    VIOsPAPRDevice *sdev;
    uint8_t buf[16];

    sdev = vty_lookup(spapr, reg);
    if (!sdev) {
        return H_PARAMETER;
    }

    if (len > 16) {
        return H_PARAMETER;
    }

    *((uint64_t *)buf) = cpu_to_be64(char0_7);
    *((uint64_t *)buf + 1) = cpu_to_be64(char8_15);

    vty_putchars(sdev, buf, len);

    return H_SUCCESS;
}

static target_ulong h_get_term_char(PowerPCCPU *cpu, sPAPREnvironment *spapr,
                                    target_ulong opcode, target_ulong *args)
{
    target_ulong reg = args[0];
    target_ulong *len = args + 0;
    target_ulong *char0_7 = args + 1;
    target_ulong *char8_15 = args + 2;
    VIOsPAPRDevice *sdev;
    uint8_t buf[16];

    sdev = vty_lookup(spapr, reg);
    if (!sdev) {
        return H_PARAMETER;
    }

    *len = vty_getchars(sdev, buf, sizeof(buf));
    if (*len < 16) {
        memset(buf + *len, 0, 16 - *len);
    }

    *char0_7 = be64_to_cpu(*((uint64_t *)buf));
    *char8_15 = be64_to_cpu(*((uint64_t *)buf + 1));

    return H_SUCCESS;
}

void spapr_vty_create(VIOsPAPRBus *bus, CharDriverState *chardev)
{
    DeviceState *dev;

    dev = qdev_create(&bus->bus, "spapr-vty");
    qdev_prop_set_chr(dev, "chardev", chardev);
    qdev_init_nofail(dev);
}

static Property spapr_vty_properties[] = {
    DEFINE_SPAPR_PROPERTIES(VIOsPAPRVTYDevice, sdev),
    DEFINE_PROP_CHR("chardev", VIOsPAPRVTYDevice, chardev),
    DEFINE_PROP_END_OF_LIST(),
};

static void spapr_vty_class_init(ObjectClass *klass, void *data)
{
    DeviceClass *dc = DEVICE_CLASS(klass);
    VIOsPAPRDeviceClass *k = VIO_SPAPR_DEVICE_CLASS(klass);

    k->init = spapr_vty_init;
    k->dt_name = "vty";
    k->dt_type = "serial";
    k->dt_compatible = "hvterm1";
    dc->props = spapr_vty_properties;
}

static const TypeInfo spapr_vty_info = {
    .name          = "spapr-vty",
    .parent        = TYPE_VIO_SPAPR_DEVICE,
    .instance_size = sizeof(VIOsPAPRVTYDevice),
    .class_init    = spapr_vty_class_init,
};

VIOsPAPRDevice *spapr_vty_get_default(VIOsPAPRBus *bus)
{
    VIOsPAPRDevice *sdev, *selected;
    BusChild *kid;

    /*
     * To avoid the console bouncing around we want one VTY to be
     * the "default". We haven't really got anything to go on, so
     * arbitrarily choose the one with the lowest reg value.
     */

    selected = NULL;
    QTAILQ_FOREACH(kid, &bus->bus.children, sibling) {
        DeviceState *iter = kid->child;

        /* Only look at VTY devices */
        if (!object_dynamic_cast(OBJECT(iter), "spapr-vty")) {
            continue;
        }

        sdev = DO_UPCAST(VIOsPAPRDevice, qdev, iter);

        /* First VTY we've found, so it is selected for now */
        if (!selected) {
            selected = sdev;
            continue;
        }

        /* Choose VTY with lowest reg value */
        if (sdev->reg < selected->reg) {
            selected = sdev;
        }
    }

    return selected;
}

VIOsPAPRDevice *vty_lookup(sPAPREnvironment *spapr, target_ulong reg)
{
    VIOsPAPRDevice *sdev;

    sdev = spapr_vio_find_by_reg(spapr->vio_bus, reg);
    if (!sdev && reg == 0) {
        /* Hack for kernel early debug, which always specifies reg==0.
         * We search all VIO devices, and grab the vty with the lowest
         * reg.  This attempts to mimic existing PowerVM behaviour
         * (early debug does work there, despite having no vty with
         * reg==0. */
        return spapr_vty_get_default(spapr->vio_bus);
    }

    return sdev;
}

static void spapr_vty_register_types(void)
{
    spapr_register_hypercall(H_PUT_TERM_CHAR, h_put_term_char);
    spapr_register_hypercall(H_GET_TERM_CHAR, h_get_term_char);
    type_register_static(&spapr_vty_info);
}

type_init(spapr_vty_register_types)