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/*

 * SCLP event type

 *    Ascii Console Data (VT220 Console)

 *

 * Copyright IBM, Corp. 2012

 *

 * Authors:

 *  Heinz Graalfs <graalfs@de.ibm.com>

 *

 * This work is licensed under the terms of the GNU GPL, version 2 or (at your

 * option) any later version.  See the COPYING file in the top-level directory.

 *

 */

#include <hw/qdev.h>

#include "qemu/thread.h"

#include "qemu/error-report.h"

#include "hw/s390x/sclp.h"

#include "hw/s390x/event-facility.h"

#include "sysemu/char.h"

typedef struct ASCIIConsoleData {

    EventBufferHeader ebh;

    char data[0];

} QEMU_PACKED ASCIIConsoleData;

/* max size for ASCII data in 4K SCCB page */

#define SIZE_BUFFER_VT220 4080

typedef struct SCLPConsole {

    SCLPEvent event;

    CharDriverState *chr;

    /* io vector                                                       */

    uint8_t *iov;           /* iov buffer pointer                      */

    uint8_t *iov_sclp;      /* pointer to SCLP read offset             */

    uint8_t *iov_bs;        /* pointer byte stream read offset         */

    uint32_t iov_data_len;  /* length of byte stream in buffer         */

    uint32_t iov_sclp_rest; /* length of byte stream not read via SCLP */

    qemu_irq irq_read_vt220;

} SCLPConsole;

/* character layer call-back functions */

/* Return number of bytes that fit into iov buffer */

static int chr_can_read(void *opaque)

{

    SCLPConsole *scon = opaque;

    return scon->iov ? SIZE_BUFFER_VT220 - scon->iov_data_len : 0;

}

/* Receive n bytes from character layer, save in iov buffer,

 * and set event pending */

static void receive_from_chr_layer(SCLPConsole *scon, const uint8_t *buf,

                                   int size)

{

    assert(scon->iov);

    /* read data must fit into current buffer */

    assert(size <= SIZE_BUFFER_VT220 - scon->iov_data_len);

    /* put byte-stream from character layer into buffer */

    memcpy(scon->iov_bs, buf, size);

    scon->iov_data_len += size;

    scon->iov_sclp_rest += size;

    scon->iov_bs += size;

    scon->event.event_pending = true;

}

/* Send data from a char device over to the guest */

static void chr_read(void *opaque, const uint8_t *buf, int size)

{

    SCLPConsole *scon = opaque;

    assert(scon);

    receive_from_chr_layer(scon, buf, size);

    /* trigger SCLP read operation */

    qemu_irq_raise(scon->irq_read_vt220);

}

static void chr_event(void *opaque, int event)

{

    SCLPConsole *scon = opaque;

    switch (event) {

    case CHR_EVENT_OPENED:

        if (!scon->iov) {

            scon->iov = g_malloc0(SIZE_BUFFER_VT220);

            scon->iov_sclp = scon->iov;

            scon->iov_bs = scon->iov;

            scon->iov_data_len = 0;

            scon->iov_sclp_rest = 0;

        }

        break;

    case CHR_EVENT_CLOSED:

        if (scon->iov) {

            g_free(scon->iov);

            scon->iov = NULL;

        }

        break;

    }

}

/* functions to be called by event facility */

static int event_type(void)

{

    return SCLP_EVENT_ASCII_CONSOLE_DATA;

}

static unsigned int send_mask(void)

{

    return SCLP_EVENT_MASK_MSG_ASCII;

}

static unsigned int receive_mask(void)

{

    return SCLP_EVENT_MASK_MSG_ASCII;

}

/* triggered by SCLP's read_event_data -

 * copy console data byte-stream into provided (SCLP) buffer

 */

static void get_console_data(SCLPEvent *event, uint8_t *buf, size_t *size,

                             int avail)

{

    SCLPConsole *cons = DO_UPCAST(SCLPConsole, event, event);

    /* first byte is hex 0 saying an ascii string follows */

    *buf++ = '\0';

    avail--;

    /* if all data fit into provided SCLP buffer */

    if (avail >= cons->iov_sclp_rest) {

        /* copy character byte-stream to SCLP buffer */

        memcpy(buf, cons->iov_sclp, cons->iov_sclp_rest);

        *size = cons->iov_sclp_rest + 1;

        cons->iov_sclp = cons->iov;

        cons->iov_bs = cons->iov;

        cons->iov_data_len = 0;

        cons->iov_sclp_rest = 0;

        event->event_pending = false;

        /* data provided and no more data pending */

    } else {

        /* if provided buffer is too small, just copy part */

        memcpy(buf, cons->iov_sclp, avail);

        *size = avail + 1;

        cons->iov_sclp_rest -= avail;

        cons->iov_sclp += avail;

        /* more data pending */

    }

}

static int read_event_data(SCLPEvent *event, EventBufferHeader *evt_buf_hdr,

                           int *slen)

{

    int avail;

    size_t src_len;

    uint8_t *to;

    ASCIIConsoleData *acd = (ASCIIConsoleData *) evt_buf_hdr;

    if (!event->event_pending) {

        /* no data pending */

        return 0;

    }

    to = (uint8_t *)&acd->data;

    avail = *slen - sizeof(ASCIIConsoleData);

    get_console_data(event, to, &src_len, avail);

    acd->ebh.length = cpu_to_be16(sizeof(ASCIIConsoleData) + src_len);

    acd->ebh.type = SCLP_EVENT_ASCII_CONSOLE_DATA;

    acd->ebh.flags |= SCLP_EVENT_BUFFER_ACCEPTED;

    *slen = avail - src_len;

    return 1;

}

/* triggered by SCLP's write_event_data

 *  - write console data to character layer

 *  returns < 0 if an error occurred

 */

static ssize_t write_console_data(SCLPEvent *event, const uint8_t *buf,

                                  size_t len)

{

    ssize_t ret = 0;

    const uint8_t *iov_offset;

    SCLPConsole *scon = DO_UPCAST(SCLPConsole, event, event);

    if (!scon->chr) {

        /* If there's no backend, we can just say we consumed all data. */

        return len;

    }

    iov_offset = buf;

    while (len > 0) {

        ret = qemu_chr_fe_write(scon->chr, buf, len);

        if (ret == 0) {

            /* a pty doesn't seem to be connected - no error */

            len = 0;

        } else if (ret == -EAGAIN || (ret > 0 && ret < len)) {

            len -= ret;

            iov_offset += ret;

        } else {

            len = 0;

        }

    }

    return ret;

}

static int write_event_data(SCLPEvent *event, EventBufferHeader *evt_buf_hdr)

{

    int rc;

    int length;

    ssize_t written;

    ASCIIConsoleData *acd = (ASCIIConsoleData *) evt_buf_hdr;

    length = be16_to_cpu(evt_buf_hdr->length) - sizeof(EventBufferHeader);

    written = write_console_data(event, (uint8_t *)acd->data, length);

    rc = SCLP_RC_NORMAL_COMPLETION;

    /* set event buffer accepted flag */

    evt_buf_hdr->flags |= SCLP_EVENT_BUFFER_ACCEPTED;

    /* written will be zero if a pty is not connected - don't treat as error */

    if (written < 0) {

        /* event buffer not accepted due to error in character layer */

        evt_buf_hdr->flags &= ~(SCLP_EVENT_BUFFER_ACCEPTED);

        rc = SCLP_RC_CONTAINED_EQUIPMENT_CHECK;

    }

    return rc;

}

static void trigger_ascii_console_data(void *opaque, int n, int level)

{

    sclp_service_interrupt(0);

}

/* qemu object creation and initialization functions */

/* tell character layer our call-back functions */

static int console_init(SCLPEvent *event)

{

    static bool console_available;

    SCLPConsole *scon = DO_UPCAST(SCLPConsole, event, event);

    if (console_available) {

        error_report("Multiple VT220 operator consoles are not supported");

        return -1;

    }

    console_available = true;

    event->event_type = SCLP_EVENT_ASCII_CONSOLE_DATA;

    if (scon->chr) {

        qemu_chr_add_handlers(scon->chr, chr_can_read,

                              chr_read, chr_event, scon);

    }

    scon->irq_read_vt220 = *qemu_allocate_irqs(trigger_ascii_console_data,

                                               NULL, 1);

    return 0;

}

static int console_exit(SCLPEvent *event)

{

    return 0;

}

static Property console_properties[] = {

    DEFINE_PROP_CHR("chardev", SCLPConsole, chr),

    DEFINE_PROP_END_OF_LIST(),

};

static void console_class_init(ObjectClass *klass, void *data)

{

    DeviceClass *dc = DEVICE_CLASS(klass);

    SCLPEventClass *ec = SCLP_EVENT_CLASS(klass);

    dc->props = console_properties;

    ec->init = console_init;

    ec->exit = console_exit;

    ec->get_send_mask = send_mask;

    ec->get_receive_mask = receive_mask;

    ec->event_type = event_type;

    ec->read_event_data = read_event_data;

    ec->write_event_data = write_event_data;

}

static const TypeInfo sclp_console_info = {

    .name          = "sclpconsole",

    .parent        = TYPE_SCLP_EVENT,

    .instance_size = sizeof(SCLPConsole),

    .class_init    = console_class_init,

    .class_size    = sizeof(SCLPEventClass),

};

static void register_types(void)

{

    type_register_static(&sclp_console_info);

}

type_init(register_types)