2 * Copyright (C) 2006, 2007, 2009 Rusty Russell, IBM Corporation
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18 #include <linux/err.h>
19 #include <linux/init.h>
20 #include <linux/virtio.h>
21 #include <linux/virtio_console.h>
22 #include "hvc_console.h"
27 /* size of the buffer in *buf above */
30 /* used length of the buffer */
32 /* offset in the buf from which to consume data */
37 struct virtqueue *in_vq, *out_vq;
38 struct virtio_device *vdev;
40 /* The current buffer from which data has to be fed to readers */
41 struct port_buffer *inbuf;
44 struct hvc_struct *hvc;
47 /* We have one port ready to go immediately, for a console. */
48 static struct port console;
50 /* This is the very early arch-specified put chars function. */
51 static int (*early_put_chars)(u32, const char *, int);
53 static void free_buf(struct port_buffer *buf)
59 static struct port_buffer *alloc_buf(size_t buf_size)
61 struct port_buffer *buf;
63 buf = kmalloc(sizeof(*buf), GFP_KERNEL);
66 buf->buf = kzalloc(buf_size, GFP_KERNEL);
81 * The put_chars() callback is pretty straightforward.
83 * We turn the characters into a scatter-gather list, add it to the
84 * output queue and then kick the Host. Then we sit here waiting for
85 * it to finish: inefficient in theory, but in practice
86 * implementations will do it immediately (lguest's Launcher does).
88 static int put_chars(u32 vtermno, const char *buf, int count)
90 struct scatterlist sg[1];
94 if (unlikely(early_put_chars))
95 return early_put_chars(vtermno, buf, count);
99 /* This is a convenient routine to initialize a single-elem sg list */
100 sg_init_one(sg, buf, count);
102 /* This shouldn't fail: if it does, we lose chars. */
103 if (port->out_vq->vq_ops->add_buf(port->out_vq, sg, 1, 0, port) >= 0) {
104 /* Tell Host to go! */
105 port->out_vq->vq_ops->kick(port->out_vq);
106 while (!port->out_vq->vq_ops->get_buf(port->out_vq, &len))
110 /* We're expected to return the amount of data we wrote: all of it. */
115 * Create a scatter-gather list representing our input buffer and put
118 static void add_inbuf(struct port *port)
120 struct scatterlist sg[1];
121 sg_init_one(sg, port->inbuf->buf, PAGE_SIZE);
123 /* Should always be able to add one buffer to an empty queue. */
124 if (port->in_vq->vq_ops->add_buf(port->in_vq, sg, 0, 1, port) < 0)
126 port->in_vq->vq_ops->kick(port->in_vq);
130 * get_chars() is the callback from the hvc_console infrastructure
131 * when an interrupt is received.
133 * Most of the code deals with the fact that the hvc_console()
134 * infrastructure only asks us for 16 bytes at a time. We keep
135 * in_offset and in_used fields for partially-filled buffers.
137 static int get_chars(u32 vtermno, char *buf, int count)
144 /* If we don't have an input queue yet, we can't get input. */
145 BUG_ON(!port->in_vq);
147 /* No more in buffer? See if they've (re)used it. */
148 if (port->inbuf->offset == port->inbuf->len) {
149 if (!port->in_vq->vq_ops->get_buf(port->in_vq, &len))
151 port->inbuf->offset = 0;
152 port->inbuf->len = len;
155 /* You want more than we have to give? Well, try wanting less! */
156 if (port->inbuf->offset + count > port->inbuf->len)
157 count = port->inbuf->len - port->inbuf->offset;
159 /* Copy across to their buffer and increment offset. */
160 memcpy(buf, port->inbuf->buf + port->inbuf->offset, count);
161 port->inbuf->offset += count;
163 /* Finished? Re-register buffer so Host will use it again. */
164 if (port->inbuf->offset == port->inbuf->len)
171 * virtio console configuration. This supports:
174 static void virtcons_apply_config(struct virtio_device *dev)
178 if (virtio_has_feature(dev, VIRTIO_CONSOLE_F_SIZE)) {
179 dev->config->get(dev,
180 offsetof(struct virtio_console_config, cols),
181 &ws.ws_col, sizeof(u16));
182 dev->config->get(dev,
183 offsetof(struct virtio_console_config, rows),
184 &ws.ws_row, sizeof(u16));
185 hvc_resize(console.hvc, ws);
190 * we support only one console, the hvc struct is a global var We set
191 * the configuration at this point, since we now have a tty
193 static int notifier_add_vio(struct hvc_struct *hp, int data)
195 hp->irq_requested = 1;
196 virtcons_apply_config(console.vdev);
201 static void notifier_del_vio(struct hvc_struct *hp, int data)
203 hp->irq_requested = 0;
206 static void hvc_handle_input(struct virtqueue *vq)
208 if (hvc_poll(console.hvc))
212 /* The operations for the console. */
213 static const struct hv_ops hv_ops = {
214 .get_chars = get_chars,
215 .put_chars = put_chars,
216 .notifier_add = notifier_add_vio,
217 .notifier_del = notifier_del_vio,
218 .notifier_hangup = notifier_del_vio,
222 * Console drivers are initialized very early so boot messages can go
223 * out, so we do things slightly differently from the generic virtio
224 * initialization of the net and block drivers.
226 * At this stage, the console is output-only. It's too early to set
227 * up a virtqueue, so we let the drivers do some boutique early-output
230 int __init virtio_cons_early_init(int (*put_chars)(u32, const char *, int))
232 early_put_chars = put_chars;
233 return hvc_instantiate(0, 0, &hv_ops);
237 * Once we're further in boot, we get probed like any other virtio
238 * device. At this stage we set up the output virtqueue.
240 * To set up and manage our virtual console, we call hvc_alloc().
241 * Since we never remove the console device we never need this pointer
244 * Finally we put our input buffer in the input queue, ready to
247 static int __devinit virtcons_probe(struct virtio_device *vdev)
249 vq_callback_t *callbacks[] = { hvc_handle_input, NULL};
250 const char *names[] = { "input", "output" };
251 struct virtqueue *vqs[2];
257 dev_warn(&port->vdev->dev,
258 "Multiple virtio-console devices not supported yet\n");
263 /* This is the scratch page we use to receive console input */
264 port->inbuf = alloc_buf(PAGE_SIZE);
270 /* Find the queues. */
271 err = vdev->config->find_vqs(vdev, 2, vqs, callbacks, names);
275 port->in_vq = vqs[0];
276 port->out_vq = vqs[1];
279 * The first argument of hvc_alloc() is the virtual console
280 * number, so we use zero. The second argument is the
281 * parameter for the notification mechanism (like irq
282 * number). We currently leave this as zero, virtqueues have
283 * implicit notifications.
285 * The third argument is a "struct hv_ops" containing the
286 * put_chars(), get_chars(), notifier_add() and notifier_del()
287 * pointers. The final argument is the output buffer size: we
288 * can do any size, so we put PAGE_SIZE here.
290 port->hvc = hvc_alloc(0, 0, &hv_ops, PAGE_SIZE);
291 if (IS_ERR(port->hvc)) {
292 err = PTR_ERR(port->hvc);
296 /* Register the input buffer the first time. */
299 /* Start using the new console output. */
300 early_put_chars = NULL;
304 vdev->config->del_vqs(vdev);
306 free_buf(port->inbuf);
311 static struct virtio_device_id id_table[] = {
312 { VIRTIO_ID_CONSOLE, VIRTIO_DEV_ANY_ID },
316 static unsigned int features[] = {
317 VIRTIO_CONSOLE_F_SIZE,
320 static struct virtio_driver virtio_console = {
321 .feature_table = features,
322 .feature_table_size = ARRAY_SIZE(features),
323 .driver.name = KBUILD_MODNAME,
324 .driver.owner = THIS_MODULE,
325 .id_table = id_table,
326 .probe = virtcons_probe,
327 .config_changed = virtcons_apply_config,
330 static int __init init(void)
332 return register_virtio_driver(&virtio_console);
336 MODULE_DEVICE_TABLE(virtio, id_table);
337 MODULE_DESCRIPTION("Virtio console driver");
338 MODULE_LICENSE("GPL");