qemu/include/hw/virtio/virtio-serial.h
Amit Shah 4add73aa60 virtio: serial: expose a 'guest_writable' callback for users
Users of virtio-serial may want to know when a port becomes writable.  A
port can stop accepting writes if the guest port is open but not being
read from.  In this case, data gets queued up in the virtqueue, and
after the vq is full, writes to the port do not succeed.

When the guest reads off a vq element, and adds a new one for the host
to put data in, we can tell users the port is available for more writes,
via the new ->guest_writable() callback.

Reviewed-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Amit Shah <amit.shah@redhat.com>
2015-03-19 17:35:40 +05:30

228 lines
6.5 KiB
C

/*
* Virtio Serial / Console Support
*
* Copyright IBM, Corp. 2008
* Copyright Red Hat, Inc. 2009, 2010
*
* Authors:
* Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
* Amit Shah <amit.shah@redhat.com>
*
* This work is licensed under the terms of the GNU GPL, version 2. See
* the COPYING file in the top-level directory.
*
*/
#ifndef _QEMU_VIRTIO_SERIAL_H
#define _QEMU_VIRTIO_SERIAL_H
#include "standard-headers/linux/virtio_console.h"
#include "hw/qdev.h"
#include "hw/virtio/virtio.h"
struct virtio_serial_conf {
/* Max. number of ports we can have for a virtio-serial device */
uint32_t max_virtserial_ports;
};
#define TYPE_VIRTIO_SERIAL_PORT "virtio-serial-port"
#define VIRTIO_SERIAL_PORT(obj) \
OBJECT_CHECK(VirtIOSerialPort, (obj), TYPE_VIRTIO_SERIAL_PORT)
#define VIRTIO_SERIAL_PORT_CLASS(klass) \
OBJECT_CLASS_CHECK(VirtIOSerialPortClass, (klass), TYPE_VIRTIO_SERIAL_PORT)
#define VIRTIO_SERIAL_PORT_GET_CLASS(obj) \
OBJECT_GET_CLASS(VirtIOSerialPortClass, (obj), TYPE_VIRTIO_SERIAL_PORT)
typedef struct VirtIOSerial VirtIOSerial;
typedef struct VirtIOSerialBus VirtIOSerialBus;
typedef struct VirtIOSerialPort VirtIOSerialPort;
typedef struct VirtIOSerialPortClass {
DeviceClass parent_class;
/* Is this a device that binds with hvc in the guest? */
bool is_console;
/*
* The per-port (or per-app) realize function that's called when a
* new device is found on the bus.
*/
DeviceRealize realize;
/*
* Per-port unrealize function that's called when a port gets
* hot-unplugged or removed.
*/
DeviceUnrealize unrealize;
/* Callbacks for guest events */
/* Guest opened/closed device. */
void (*set_guest_connected)(VirtIOSerialPort *port, int guest_connected);
/* Guest is now ready to accept data (virtqueues set up). */
void (*guest_ready)(VirtIOSerialPort *port);
/*
* Guest has enqueued a buffer for the host to write into.
* Called each time a buffer is enqueued by the guest;
* irrespective of whether there already were free buffers the
* host could have consumed.
*
* This is dependent on both the guest and host end being
* connected.
*/
void (*guest_writable)(VirtIOSerialPort *port);
/*
* Guest wrote some data to the port. This data is handed over to
* the app via this callback. The app can return a size less than
* 'len'. In this case, throttling will be enabled for this port.
*/
ssize_t (*have_data)(VirtIOSerialPort *port, const uint8_t *buf,
ssize_t len);
} VirtIOSerialPortClass;
/*
* This is the state that's shared between all the ports. Some of the
* state is configurable via command-line options. Some of it can be
* set by individual devices in their initfn routines. Some of the
* state is set by the generic qdev device init routine.
*/
struct VirtIOSerialPort {
DeviceState dev;
QTAILQ_ENTRY(VirtIOSerialPort) next;
/*
* This field gives us the virtio device as well as the qdev bus
* that we are associated with
*/
VirtIOSerial *vser;
VirtQueue *ivq, *ovq;
/*
* This name is sent to the guest and exported via sysfs.
* The guest could create symlinks based on this information.
* The name is in the reverse fqdn format, like org.qemu.console.0
*/
char *name;
/*
* This id helps identify ports between the guest and the host.
* The guest sends a "header" with this id with each data packet
* that it sends and the host can then find out which associated
* device to send out this data to
*/
uint32_t id;
/*
* This is the elem that we pop from the virtqueue. A slow
* backend that consumes guest data (e.g. the file backend for
* qemu chardevs) can cause the guest to block till all the output
* is flushed. This isn't desired, so we keep a note of the last
* element popped and continue consuming it once the backend
* becomes writable again.
*/
VirtQueueElement elem;
/*
* The index and the offset into the iov buffer that was popped in
* elem above.
*/
uint32_t iov_idx;
uint64_t iov_offset;
/*
* When unthrottling we use a bottom-half to call flush_queued_data.
*/
QEMUBH *bh;
/* Is the corresponding guest device open? */
bool guest_connected;
/* Is this device open for IO on the host? */
bool host_connected;
/* Do apps not want to receive data? */
bool throttled;
};
/* The virtio-serial bus on top of which the ports will ride as devices */
struct VirtIOSerialBus {
BusState qbus;
/* This is the parent device that provides the bus for ports. */
VirtIOSerial *vser;
/* The maximum number of ports that can ride on top of this bus */
uint32_t max_nr_ports;
};
typedef struct VirtIOSerialPostLoad {
QEMUTimer *timer;
uint32_t nr_active_ports;
struct {
VirtIOSerialPort *port;
uint8_t host_connected;
} *connected;
} VirtIOSerialPostLoad;
struct VirtIOSerial {
VirtIODevice parent_obj;
VirtQueue *c_ivq, *c_ovq;
/* Arrays of ivqs and ovqs: one per port */
VirtQueue **ivqs, **ovqs;
VirtIOSerialBus bus;
QTAILQ_HEAD(, VirtIOSerialPort) ports;
QLIST_ENTRY(VirtIOSerial) next;
/* bitmap for identifying active ports */
uint32_t *ports_map;
struct VirtIOSerialPostLoad *post_load;
virtio_serial_conf serial;
};
/* Interface to the virtio-serial bus */
/*
* Open a connection to the port
* Returns 0 on success (always).
*/
int virtio_serial_open(VirtIOSerialPort *port);
/*
* Close the connection to the port
* Returns 0 on success (always).
*/
int virtio_serial_close(VirtIOSerialPort *port);
/*
* Send data to Guest
*/
ssize_t virtio_serial_write(VirtIOSerialPort *port, const uint8_t *buf,
size_t size);
/*
* Query whether a guest is ready to receive data.
*/
size_t virtio_serial_guest_ready(VirtIOSerialPort *port);
/*
* Flow control: Ports can signal to the virtio-serial core to stop
* sending data or re-start sending data, depending on the 'throttle'
* value here.
*/
void virtio_serial_throttle_port(VirtIOSerialPort *port, bool throttle);
#define TYPE_VIRTIO_SERIAL "virtio-serial-device"
#define VIRTIO_SERIAL(obj) \
OBJECT_CHECK(VirtIOSerial, (obj), TYPE_VIRTIO_SERIAL)
#define DEFINE_VIRTIO_SERIAL_PROPERTIES(_state, _field) \
DEFINE_PROP_UINT32("max_ports", _state, _field.max_virtserial_ports, 31)
#endif