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![Amit Shah](/assets/img/avatar_default.png)
This makes taking locks around the get_buf vq operation easier, as well as complements the add_inbuf() operation. Signed-off-by: Amit Shah <amit.shah@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
352 lines
8.9 KiB
C
352 lines
8.9 KiB
C
/*
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* Copyright (C) 2006, 2007, 2009 Rusty Russell, IBM Corporation
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include <linux/err.h>
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#include <linux/init.h>
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#include <linux/virtio.h>
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#include <linux/virtio_console.h>
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#include "hvc_console.h"
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struct port_buffer {
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char *buf;
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/* size of the buffer in *buf above */
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size_t size;
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/* used length of the buffer */
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size_t len;
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/* offset in the buf from which to consume data */
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size_t offset;
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};
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struct port {
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struct virtqueue *in_vq, *out_vq;
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struct virtio_device *vdev;
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/* The current buffer from which data has to be fed to readers */
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struct port_buffer *inbuf;
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/* The hvc device */
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struct hvc_struct *hvc;
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};
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/* We have one port ready to go immediately, for a console. */
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static struct port console;
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/* This is the very early arch-specified put chars function. */
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static int (*early_put_chars)(u32, const char *, int);
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static void free_buf(struct port_buffer *buf)
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{
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kfree(buf->buf);
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kfree(buf);
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}
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static struct port_buffer *alloc_buf(size_t buf_size)
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{
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struct port_buffer *buf;
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buf = kmalloc(sizeof(*buf), GFP_KERNEL);
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if (!buf)
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goto fail;
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buf->buf = kzalloc(buf_size, GFP_KERNEL);
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if (!buf->buf)
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goto free_buf;
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buf->len = 0;
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buf->offset = 0;
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buf->size = buf_size;
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return buf;
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free_buf:
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kfree(buf);
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fail:
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return NULL;
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}
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/* Callers should take appropriate locks */
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static void *get_inbuf(struct port *port)
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{
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struct port_buffer *buf;
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struct virtqueue *vq;
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unsigned int len;
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vq = port->in_vq;
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buf = vq->vq_ops->get_buf(vq, &len);
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if (buf) {
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buf->len = len;
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buf->offset = 0;
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}
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return buf;
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}
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/*
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* Create a scatter-gather list representing our input buffer and put
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* it in the queue.
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*
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* Callers should take appropriate locks.
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*/
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static void add_inbuf(struct virtqueue *vq, struct port_buffer *buf)
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{
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struct scatterlist sg[1];
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sg_init_one(sg, buf->buf, buf->size);
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if (vq->vq_ops->add_buf(vq, sg, 0, 1, buf) < 0)
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BUG();
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vq->vq_ops->kick(vq);
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}
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/*
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* The put_chars() callback is pretty straightforward.
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*
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* We turn the characters into a scatter-gather list, add it to the
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* output queue and then kick the Host. Then we sit here waiting for
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* it to finish: inefficient in theory, but in practice
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* implementations will do it immediately (lguest's Launcher does).
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*/
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static int put_chars(u32 vtermno, const char *buf, int count)
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{
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struct scatterlist sg[1];
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unsigned int len;
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struct port *port;
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if (unlikely(early_put_chars))
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return early_put_chars(vtermno, buf, count);
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port = &console;
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/* This is a convenient routine to initialize a single-elem sg list */
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sg_init_one(sg, buf, count);
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/* This shouldn't fail: if it does, we lose chars. */
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if (port->out_vq->vq_ops->add_buf(port->out_vq, sg, 1, 0, port) >= 0) {
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/* Tell Host to go! */
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port->out_vq->vq_ops->kick(port->out_vq);
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while (!port->out_vq->vq_ops->get_buf(port->out_vq, &len))
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cpu_relax();
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}
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/* We're expected to return the amount of data we wrote: all of it. */
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return count;
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}
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/*
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* get_chars() is the callback from the hvc_console infrastructure
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* when an interrupt is received.
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*
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* Most of the code deals with the fact that the hvc_console()
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* infrastructure only asks us for 16 bytes at a time. We keep
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* in_offset and in_used fields for partially-filled buffers.
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*/
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static int get_chars(u32 vtermno, char *buf, int count)
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{
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struct port *port;
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port = &console;
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/* If we don't have an input queue yet, we can't get input. */
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BUG_ON(!port->in_vq);
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/* No more in buffer? See if they've (re)used it. */
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if (port->inbuf->offset == port->inbuf->len) {
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if (!get_inbuf(port))
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return 0;
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}
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/* You want more than we have to give? Well, try wanting less! */
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if (port->inbuf->offset + count > port->inbuf->len)
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count = port->inbuf->len - port->inbuf->offset;
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/* Copy across to their buffer and increment offset. */
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memcpy(buf, port->inbuf->buf + port->inbuf->offset, count);
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port->inbuf->offset += count;
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/* Finished? Re-register buffer so Host will use it again. */
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if (port->inbuf->offset == port->inbuf->len)
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add_inbuf(port->in_vq, port->inbuf);
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return count;
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}
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/*
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* virtio console configuration. This supports:
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* - console resize
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*/
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static void virtcons_apply_config(struct virtio_device *dev)
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{
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struct winsize ws;
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if (virtio_has_feature(dev, VIRTIO_CONSOLE_F_SIZE)) {
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dev->config->get(dev,
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offsetof(struct virtio_console_config, cols),
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&ws.ws_col, sizeof(u16));
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dev->config->get(dev,
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offsetof(struct virtio_console_config, rows),
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&ws.ws_row, sizeof(u16));
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hvc_resize(console.hvc, ws);
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}
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}
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/*
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* we support only one console, the hvc struct is a global var We set
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* the configuration at this point, since we now have a tty
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*/
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static int notifier_add_vio(struct hvc_struct *hp, int data)
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{
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hp->irq_requested = 1;
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virtcons_apply_config(console.vdev);
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return 0;
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}
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static void notifier_del_vio(struct hvc_struct *hp, int data)
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{
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hp->irq_requested = 0;
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}
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static void hvc_handle_input(struct virtqueue *vq)
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{
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if (hvc_poll(console.hvc))
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hvc_kick();
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}
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/* The operations for the console. */
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static const struct hv_ops hv_ops = {
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.get_chars = get_chars,
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.put_chars = put_chars,
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.notifier_add = notifier_add_vio,
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.notifier_del = notifier_del_vio,
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.notifier_hangup = notifier_del_vio,
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};
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/*
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* Console drivers are initialized very early so boot messages can go
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* out, so we do things slightly differently from the generic virtio
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* initialization of the net and block drivers.
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*
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* At this stage, the console is output-only. It's too early to set
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* up a virtqueue, so we let the drivers do some boutique early-output
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* thing.
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*/
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int __init virtio_cons_early_init(int (*put_chars)(u32, const char *, int))
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{
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early_put_chars = put_chars;
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return hvc_instantiate(0, 0, &hv_ops);
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}
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/*
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* Once we're further in boot, we get probed like any other virtio
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* device. At this stage we set up the output virtqueue.
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*
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* To set up and manage our virtual console, we call hvc_alloc().
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* Since we never remove the console device we never need this pointer
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* again.
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*
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* Finally we put our input buffer in the input queue, ready to
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* receive.
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*/
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static int __devinit virtcons_probe(struct virtio_device *vdev)
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{
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vq_callback_t *callbacks[] = { hvc_handle_input, NULL};
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const char *names[] = { "input", "output" };
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struct virtqueue *vqs[2];
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struct port *port;
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int err;
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port = &console;
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if (port->vdev) {
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dev_warn(&port->vdev->dev,
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"Multiple virtio-console devices not supported yet\n");
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return -EEXIST;
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}
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port->vdev = vdev;
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/* This is the scratch page we use to receive console input */
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port->inbuf = alloc_buf(PAGE_SIZE);
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if (!port->inbuf) {
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err = -ENOMEM;
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goto fail;
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}
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/* Find the queues. */
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err = vdev->config->find_vqs(vdev, 2, vqs, callbacks, names);
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if (err)
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goto free;
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port->in_vq = vqs[0];
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port->out_vq = vqs[1];
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/*
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* The first argument of hvc_alloc() is the virtual console
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* number, so we use zero. The second argument is the
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* parameter for the notification mechanism (like irq
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* number). We currently leave this as zero, virtqueues have
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* implicit notifications.
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*
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* The third argument is a "struct hv_ops" containing the
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* put_chars(), get_chars(), notifier_add() and notifier_del()
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* pointers. The final argument is the output buffer size: we
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* can do any size, so we put PAGE_SIZE here.
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*/
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port->hvc = hvc_alloc(0, 0, &hv_ops, PAGE_SIZE);
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if (IS_ERR(port->hvc)) {
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err = PTR_ERR(port->hvc);
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goto free_vqs;
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}
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/* Register the input buffer the first time. */
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add_inbuf(port->in_vq, port->inbuf);
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/* Start using the new console output. */
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early_put_chars = NULL;
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return 0;
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free_vqs:
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vdev->config->del_vqs(vdev);
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free:
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free_buf(port->inbuf);
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fail:
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return err;
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}
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static struct virtio_device_id id_table[] = {
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{ VIRTIO_ID_CONSOLE, VIRTIO_DEV_ANY_ID },
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{ 0 },
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};
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static unsigned int features[] = {
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VIRTIO_CONSOLE_F_SIZE,
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};
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static struct virtio_driver virtio_console = {
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.feature_table = features,
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.feature_table_size = ARRAY_SIZE(features),
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.driver.name = KBUILD_MODNAME,
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.driver.owner = THIS_MODULE,
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.id_table = id_table,
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.probe = virtcons_probe,
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.config_changed = virtcons_apply_config,
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};
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static int __init init(void)
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{
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return register_virtio_driver(&virtio_console);
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}
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module_init(init);
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MODULE_DEVICE_TABLE(virtio, id_table);
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MODULE_DESCRIPTION("Virtio console driver");
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MODULE_LICENSE("GPL");
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