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 {
36 * This is used to keep track of the number of hvc consoles
37 * spawned by this driver. This number is given as the first
38 * argument to hvc_alloc(). To correctly map an initial
39 * console spawned via hvc_instantiate to the console being
40 * hooked up via hvc_alloc, we need to pass the same vtermno.
42 * We also just assume the first console being initialised was
43 * the first one that got used as the initial console.
45 unsigned int next_vtermno;
47 /* All the console devices handled by this driver */
48 struct list_head consoles;
50 static struct ports_driver_data pdrvdata;
52 DEFINE_SPINLOCK(pdrvdata_lock);
55 * This is a per-device struct that stores data common to all the
56 * ports for that device (vdev->priv).
59 struct virtqueue *in_vq, *out_vq;
60 struct virtio_device *vdev;
66 /* size of the buffer in *buf above */
69 /* used length of the buffer */
71 /* offset in the buf from which to consume data */
75 /* This struct holds the per-port data */
77 /* Pointer to the parent virtio_console device */
78 struct ports_device *portdev;
80 /* The current buffer from which data has to be fed to readers */
81 struct port_buffer *inbuf;
83 /* The IO vqs for this port */
84 struct virtqueue *in_vq, *out_vq;
86 /* For console ports, hvc != NULL and these are valid. */
88 struct hvc_struct *hvc;
90 /* We'll place all consoles in a list in the pdrvdata struct */
91 struct list_head list;
93 /* Our vterm number. */
97 /* This is the very early arch-specified put chars function. */
98 static int (*early_put_chars)(u32, const char *, int);
100 static struct port *find_port_by_vtermno(u32 vtermno)
105 spin_lock_irqsave(&pdrvdata_lock, flags);
106 list_for_each_entry(port, &pdrvdata.consoles, list) {
107 if (port->vtermno == vtermno)
112 spin_unlock_irqrestore(&pdrvdata_lock, flags);
116 static void free_buf(struct port_buffer *buf)
122 static struct port_buffer *alloc_buf(size_t buf_size)
124 struct port_buffer *buf;
126 buf = kmalloc(sizeof(*buf), GFP_KERNEL);
129 buf->buf = kzalloc(buf_size, GFP_KERNEL);
134 buf->size = buf_size;
143 /* Callers should take appropriate locks */
144 static void *get_inbuf(struct port *port)
146 struct port_buffer *buf;
147 struct virtqueue *vq;
151 buf = vq->vq_ops->get_buf(vq, &len);
160 * Create a scatter-gather list representing our input buffer and put
163 * Callers should take appropriate locks.
165 static void add_inbuf(struct virtqueue *vq, struct port_buffer *buf)
167 struct scatterlist sg[1];
169 sg_init_one(sg, buf->buf, buf->size);
171 if (vq->vq_ops->add_buf(vq, sg, 0, 1, buf) < 0)
173 vq->vq_ops->kick(vq);
177 * The put_chars() callback is pretty straightforward.
179 * We turn the characters into a scatter-gather list, add it to the
180 * output queue and then kick the Host. Then we sit here waiting for
181 * it to finish: inefficient in theory, but in practice
182 * implementations will do it immediately (lguest's Launcher does).
184 static int put_chars(u32 vtermno, const char *buf, int count)
186 struct scatterlist sg[1];
188 struct virtqueue *out_vq;
191 port = find_port_by_vtermno(vtermno);
195 if (unlikely(early_put_chars))
196 return early_put_chars(vtermno, buf, count);
198 out_vq = port->out_vq;
199 /* This is a convenient routine to initialize a single-elem sg list */
200 sg_init_one(sg, buf, count);
202 /* This shouldn't fail: if it does, we lose chars. */
203 if (out_vq->vq_ops->add_buf(out_vq, sg, 1, 0, port) >= 0) {
204 /* Tell Host to go! */
205 out_vq->vq_ops->kick(out_vq);
206 while (!out_vq->vq_ops->get_buf(out_vq, &len))
210 /* We're expected to return the amount of data we wrote: all of it. */
215 * get_chars() is the callback from the hvc_console infrastructure
216 * when an interrupt is received.
218 * Most of the code deals with the fact that the hvc_console()
219 * infrastructure only asks us for 16 bytes at a time. We keep
220 * in_offset and in_used fields for partially-filled buffers.
222 static int get_chars(u32 vtermno, char *buf, int count)
226 port = find_port_by_vtermno(vtermno);
230 /* If we don't have an input queue yet, we can't get input. */
231 BUG_ON(!port->in_vq);
233 /* No more in buffer? See if they've (re)used it. */
234 if (port->inbuf->offset == port->inbuf->len) {
235 if (!get_inbuf(port))
239 /* You want more than we have to give? Well, try wanting less! */
240 if (port->inbuf->offset + count > port->inbuf->len)
241 count = port->inbuf->len - port->inbuf->offset;
243 /* Copy across to their buffer and increment offset. */
244 memcpy(buf, port->inbuf->buf + port->inbuf->offset, count);
245 port->inbuf->offset += count;
247 /* Finished? Re-register buffer so Host will use it again. */
248 if (port->inbuf->offset == port->inbuf->len)
249 add_inbuf(port->in_vq, port->inbuf);
255 * virtio console configuration. This supports:
258 static void virtcons_apply_config(struct virtio_device *dev)
262 if (virtio_has_feature(dev, VIRTIO_CONSOLE_F_SIZE)) {
263 dev->config->get(dev,
264 offsetof(struct virtio_console_config, cols),
265 &ws.ws_col, sizeof(u16));
266 dev->config->get(dev,
267 offsetof(struct virtio_console_config, rows),
268 &ws.ws_row, sizeof(u16));
269 /* This is the pre-multiport style: we use control messages
270 * these days which specify the port. So this means port 0. */
271 hvc_resize(find_port_by_vtermno(0)->hvc, ws);
275 /* We set the configuration at this point, since we now have a tty */
276 static int notifier_add_vio(struct hvc_struct *hp, int data)
280 port = find_port_by_vtermno(hp->vtermno);
284 hp->irq_requested = 1;
285 virtcons_apply_config(port->portdev->vdev);
290 static void notifier_del_vio(struct hvc_struct *hp, int data)
292 hp->irq_requested = 0;
295 static void hvc_handle_input(struct virtqueue *vq)
298 bool activity = false;
300 list_for_each_entry(port, &pdrvdata.consoles, list)
301 activity |= hvc_poll(port->hvc);
307 /* The operations for the console. */
308 static const struct hv_ops hv_ops = {
309 .get_chars = get_chars,
310 .put_chars = put_chars,
311 .notifier_add = notifier_add_vio,
312 .notifier_del = notifier_del_vio,
313 .notifier_hangup = notifier_del_vio,
317 * Console drivers are initialized very early so boot messages can go
318 * out, so we do things slightly differently from the generic virtio
319 * initialization of the net and block drivers.
321 * At this stage, the console is output-only. It's too early to set
322 * up a virtqueue, so we let the drivers do some boutique early-output
325 int __init virtio_cons_early_init(int (*put_chars)(u32, const char *, int))
327 early_put_chars = put_chars;
328 return hvc_instantiate(0, 0, &hv_ops);
331 static int __devinit add_port(struct ports_device *portdev)
336 port = kmalloc(sizeof(*port), GFP_KERNEL);
342 port->portdev = portdev;
343 port->in_vq = portdev->in_vq;
344 port->out_vq = portdev->out_vq;
346 port->inbuf = alloc_buf(PAGE_SIZE);
353 * The first argument of hvc_alloc() is the virtual console
354 * number. The second argument is the parameter for the
355 * notification mechanism (like irq number). We currently
356 * leave this as zero, virtqueues have implicit notifications.
358 * The third argument is a "struct hv_ops" containing the
359 * put_chars(), get_chars(), notifier_add() and notifier_del()
360 * pointers. The final argument is the output buffer size: we
361 * can do any size, so we put PAGE_SIZE here.
363 port->vtermno = pdrvdata.next_vtermno;
364 port->hvc = hvc_alloc(port->vtermno, 0, &hv_ops, PAGE_SIZE);
365 if (IS_ERR(port->hvc)) {
366 err = PTR_ERR(port->hvc);
370 /* Add to vtermno list. */
371 spin_lock_irq(&pdrvdata_lock);
372 pdrvdata.next_vtermno++;
373 list_add(&port->list, &pdrvdata.consoles);
374 spin_unlock_irq(&pdrvdata_lock);
376 /* Register the input buffer the first time. */
377 add_inbuf(port->in_vq, port->inbuf);
382 free_buf(port->inbuf);
390 * Once we're further in boot, we get probed like any other virtio
393 static int __devinit virtcons_probe(struct virtio_device *vdev)
395 vq_callback_t *callbacks[] = { hvc_handle_input, NULL};
396 const char *names[] = { "input", "output" };
397 struct virtqueue *vqs[2];
398 struct ports_device *portdev;
401 portdev = kmalloc(sizeof(*portdev), GFP_KERNEL);
407 /* Attach this portdev to this virtio_device, and vice-versa. */
408 portdev->vdev = vdev;
409 vdev->priv = portdev;
411 /* Find the queues. */
412 err = vdev->config->find_vqs(vdev, 2, vqs, callbacks, names);
416 portdev->in_vq = vqs[0];
417 portdev->out_vq = vqs[1];
419 /* We only have one port. */
420 err = add_port(portdev);
424 /* Start using the new console output. */
425 early_put_chars = NULL;
429 vdev->config->del_vqs(vdev);
436 static struct virtio_device_id id_table[] = {
437 { VIRTIO_ID_CONSOLE, VIRTIO_DEV_ANY_ID },
441 static unsigned int features[] = {
442 VIRTIO_CONSOLE_F_SIZE,
445 static struct virtio_driver virtio_console = {
446 .feature_table = features,
447 .feature_table_size = ARRAY_SIZE(features),
448 .driver.name = KBUILD_MODNAME,
449 .driver.owner = THIS_MODULE,
450 .id_table = id_table,
451 .probe = virtcons_probe,
452 .config_changed = virtcons_apply_config,
455 static int __init init(void)
457 INIT_LIST_HEAD(&pdrvdata.consoles);
459 return register_virtio_driver(&virtio_console);
463 MODULE_DEVICE_TABLE(virtio, id_table);
464 MODULE_DESCRIPTION("Virtio console driver");
465 MODULE_LICENSE("GPL");