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/list.h>
21 #include <linux/spinlock.h>
22 #include <linux/virtio.h>
23 #include <linux/virtio_console.h>
24 #include "hvc_console.h"
27 * This is a global struct for storing common data for all the devices
28 * this driver handles.
30 * Mainly, it has a linked list for all the consoles in one place so
31 * that callbacks from hvc for get_chars(), put_chars() work properly
32 * across multiple devices and multiple ports per device.
34 struct ports_driver_data {
35 /* All the console devices handled by this driver */
36 struct list_head consoles;
38 static struct ports_driver_data pdrvdata;
40 DEFINE_SPINLOCK(pdrvdata_lock);
45 /* size of the buffer in *buf above */
48 /* used length of the buffer */
50 /* offset in the buf from which to consume data */
55 struct virtqueue *in_vq, *out_vq;
56 struct virtio_device *vdev;
58 /* The current buffer from which data has to be fed to readers */
59 struct port_buffer *inbuf;
61 /* For console ports, hvc != NULL and these are valid. */
63 struct hvc_struct *hvc;
65 /* We'll place all consoles in a list in the pdrvdata struct */
66 struct list_head list;
68 /* Our vterm number. */
72 /* We have one port ready to go immediately, for a console. */
73 static struct port console;
75 /* This is the very early arch-specified put chars function. */
76 static int (*early_put_chars)(u32, const char *, int);
78 static struct port *find_port_by_vtermno(u32 vtermno)
83 spin_lock_irqsave(&pdrvdata_lock, flags);
84 list_for_each_entry(port, &pdrvdata.consoles, list) {
85 if (port->vtermno == vtermno)
90 spin_unlock_irqrestore(&pdrvdata_lock, flags);
94 static void free_buf(struct port_buffer *buf)
100 static struct port_buffer *alloc_buf(size_t buf_size)
102 struct port_buffer *buf;
104 buf = kmalloc(sizeof(*buf), GFP_KERNEL);
107 buf->buf = kzalloc(buf_size, GFP_KERNEL);
112 buf->size = buf_size;
121 /* Callers should take appropriate locks */
122 static void *get_inbuf(struct port *port)
124 struct port_buffer *buf;
125 struct virtqueue *vq;
129 buf = vq->vq_ops->get_buf(vq, &len);
138 * Create a scatter-gather list representing our input buffer and put
141 * Callers should take appropriate locks.
143 static void add_inbuf(struct virtqueue *vq, struct port_buffer *buf)
145 struct scatterlist sg[1];
146 sg_init_one(sg, buf->buf, buf->size);
148 if (vq->vq_ops->add_buf(vq, sg, 0, 1, buf) < 0)
150 vq->vq_ops->kick(vq);
154 * The put_chars() callback is pretty straightforward.
156 * We turn the characters into a scatter-gather list, add it to the
157 * output queue and then kick the Host. Then we sit here waiting for
158 * it to finish: inefficient in theory, but in practice
159 * implementations will do it immediately (lguest's Launcher does).
161 static int put_chars(u32 vtermno, const char *buf, int count)
163 struct scatterlist sg[1];
167 port = find_port_by_vtermno(vtermno);
171 if (unlikely(early_put_chars))
172 return early_put_chars(vtermno, buf, count);
174 /* This is a convenient routine to initialize a single-elem sg list */
175 sg_init_one(sg, buf, count);
177 /* This shouldn't fail: if it does, we lose chars. */
178 if (port->out_vq->vq_ops->add_buf(port->out_vq, sg, 1, 0, port) >= 0) {
179 /* Tell Host to go! */
180 port->out_vq->vq_ops->kick(port->out_vq);
181 while (!port->out_vq->vq_ops->get_buf(port->out_vq, &len))
185 /* We're expected to return the amount of data we wrote: all of it. */
190 * get_chars() is the callback from the hvc_console infrastructure
191 * when an interrupt is received.
193 * Most of the code deals with the fact that the hvc_console()
194 * infrastructure only asks us for 16 bytes at a time. We keep
195 * in_offset and in_used fields for partially-filled buffers.
197 static int get_chars(u32 vtermno, char *buf, int count)
202 port = find_port_by_vtermno(vtermno);
206 /* If we don't have an input queue yet, we can't get input. */
207 BUG_ON(!port->in_vq);
209 /* No more in buffer? See if they've (re)used it. */
210 if (port->inbuf->offset == port->inbuf->len) {
211 if (!get_inbuf(port))
215 /* You want more than we have to give? Well, try wanting less! */
216 if (port->inbuf->offset + count > port->inbuf->len)
217 count = port->inbuf->len - port->inbuf->offset;
219 /* Copy across to their buffer and increment offset. */
220 memcpy(buf, port->inbuf->buf + port->inbuf->offset, count);
221 port->inbuf->offset += count;
223 /* Finished? Re-register buffer so Host will use it again. */
224 if (port->inbuf->offset == port->inbuf->len)
225 add_inbuf(port->in_vq, port->inbuf);
231 * virtio console configuration. This supports:
234 static void virtcons_apply_config(struct virtio_device *dev)
236 struct port *port = dev->priv;
239 if (virtio_has_feature(dev, VIRTIO_CONSOLE_F_SIZE)) {
240 dev->config->get(dev,
241 offsetof(struct virtio_console_config, cols),
242 &ws.ws_col, sizeof(u16));
243 dev->config->get(dev,
244 offsetof(struct virtio_console_config, rows),
245 &ws.ws_row, sizeof(u16));
246 hvc_resize(port->hvc, ws);
250 /* We set the configuration at this point, since we now have a tty */
251 static int notifier_add_vio(struct hvc_struct *hp, int data)
255 port = find_port_by_vtermno(hp->vtermno);
259 hp->irq_requested = 1;
260 virtcons_apply_config(port->vdev);
265 static void notifier_del_vio(struct hvc_struct *hp, int data)
267 hp->irq_requested = 0;
270 static void hvc_handle_input(struct virtqueue *vq)
272 struct port *port = vq->vdev->priv;
274 if (hvc_poll(port->hvc))
278 /* The operations for the console. */
279 static const struct hv_ops hv_ops = {
280 .get_chars = get_chars,
281 .put_chars = put_chars,
282 .notifier_add = notifier_add_vio,
283 .notifier_del = notifier_del_vio,
284 .notifier_hangup = notifier_del_vio,
288 * Console drivers are initialized very early so boot messages can go
289 * out, so we do things slightly differently from the generic virtio
290 * initialization of the net and block drivers.
292 * At this stage, the console is output-only. It's too early to set
293 * up a virtqueue, so we let the drivers do some boutique early-output
296 int __init virtio_cons_early_init(int (*put_chars)(u32, const char *, int))
298 early_put_chars = put_chars;
299 return hvc_instantiate(0, 0, &hv_ops);
303 * Once we're further in boot, we get probed like any other virtio
304 * device. At this stage we set up the output virtqueue.
306 * To set up and manage our virtual console, we call hvc_alloc().
307 * Since we never remove the console device we never need this pointer
310 * Finally we put our input buffer in the input queue, ready to
313 static int __devinit virtcons_probe(struct virtio_device *vdev)
315 vq_callback_t *callbacks[] = { hvc_handle_input, NULL};
316 const char *names[] = { "input", "output" };
317 struct virtqueue *vqs[2];
323 dev_warn(&port->vdev->dev,
324 "Multiple virtio-console devices not supported yet\n");
328 /* Attach this port to this virtio_device, and vice-versa. */
332 /* This is the scratch page we use to receive console input */
333 port->inbuf = alloc_buf(PAGE_SIZE);
339 /* Find the queues. */
340 err = vdev->config->find_vqs(vdev, 2, vqs, callbacks, names);
344 port->in_vq = vqs[0];
345 port->out_vq = vqs[1];
348 * The first argument of hvc_alloc() is the virtual console
349 * number, so we use zero. The second argument is the
350 * parameter for the notification mechanism (like irq
351 * number). We currently leave this as zero, virtqueues have
352 * implicit notifications.
354 * The third argument is a "struct hv_ops" containing the
355 * put_chars(), get_chars(), notifier_add() and notifier_del()
356 * pointers. The final argument is the output buffer size: we
357 * can do any size, so we put PAGE_SIZE here.
359 port->hvc = hvc_alloc(0, 0, &hv_ops, PAGE_SIZE);
360 if (IS_ERR(port->hvc)) {
361 err = PTR_ERR(port->hvc);
365 /* Add to vtermno list. */
366 spin_lock_irq(&pdrvdata_lock);
367 list_add(&port->list, &pdrvdata.consoles);
368 spin_unlock_irq(&pdrvdata_lock);
370 /* Register the input buffer the first time. */
371 add_inbuf(port->in_vq, port->inbuf);
373 /* Start using the new console output. */
374 early_put_chars = NULL;
378 vdev->config->del_vqs(vdev);
380 free_buf(port->inbuf);
385 static struct virtio_device_id id_table[] = {
386 { VIRTIO_ID_CONSOLE, VIRTIO_DEV_ANY_ID },
390 static unsigned int features[] = {
391 VIRTIO_CONSOLE_F_SIZE,
394 static struct virtio_driver virtio_console = {
395 .feature_table = features,
396 .feature_table_size = ARRAY_SIZE(features),
397 .driver.name = KBUILD_MODNAME,
398 .driver.owner = THIS_MODULE,
399 .id_table = id_table,
400 .probe = virtcons_probe,
401 .config_changed = virtcons_apply_config,
404 static int __init init(void)
406 INIT_LIST_HEAD(&pdrvdata.consoles);
408 return register_virtio_driver(&virtio_console);
412 MODULE_DEVICE_TABLE(virtio, id_table);
413 MODULE_DESCRIPTION("Virtio console driver");
414 MODULE_LICENSE("GPL");