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"
24 static struct virtqueue *in_vq, *out_vq;
25 static struct virtio_device *vdev;
27 /* This is our input buffer, and how much data is left in it. */
28 static unsigned int in_len;
29 static char *in, *inbuf;
32 static struct hvc_struct *hvc;
34 /* This is the very early arch-specified put chars function. */
35 static int (*early_put_chars)(u32, const char *, int);
38 * The put_chars() callback is pretty straightforward.
40 * We turn the characters into a scatter-gather list, add it to the
41 * output queue and then kick the Host. Then we sit here waiting for
42 * it to finish: inefficient in theory, but in practice
43 * implementations will do it immediately (lguest's Launcher does).
45 static int put_chars(u32 vtermno, const char *buf, int count)
47 struct scatterlist sg[1];
50 if (unlikely(early_put_chars))
51 return early_put_chars(vtermno, buf, count);
53 /* This is a convenient routine to initialize a single-elem sg list */
54 sg_init_one(sg, buf, count);
57 * add_buf wants a token to identify this buffer: we hand it
58 * any non-NULL pointer, since there's only ever one buffer.
60 if (out_vq->vq_ops->add_buf(out_vq, sg, 1, 0, (void *)1) >= 0) {
61 /* Tell Host to go! */
62 out_vq->vq_ops->kick(out_vq);
63 /* Chill out until it's done with the buffer. */
64 while (!out_vq->vq_ops->get_buf(out_vq, &len))
68 /* We're expected to return the amount of data we wrote: all of it. */
73 * Create a scatter-gather list representing our input buffer and put
76 static void add_inbuf(void)
78 struct scatterlist sg[1];
79 sg_init_one(sg, inbuf, PAGE_SIZE);
81 /* We should always be able to add one buffer to an empty queue. */
82 if (in_vq->vq_ops->add_buf(in_vq, sg, 0, 1, inbuf) < 0)
84 in_vq->vq_ops->kick(in_vq);
88 * get_chars() is the callback from the hvc_console infrastructure
89 * when an interrupt is received.
91 * Most of the code deals with the fact that the hvc_console()
92 * infrastructure only asks us for 16 bytes at a time. We keep
93 * in_offset and in_used fields for partially-filled buffers.
95 static int get_chars(u32 vtermno, char *buf, int count)
97 /* If we don't have an input queue yet, we can't get input. */
100 /* No buffer? Try to get one. */
102 in = in_vq->vq_ops->get_buf(in_vq, &in_len);
107 /* You want more than we have to give? Well, try wanting less! */
111 /* Copy across to their buffer and increment offset. */
112 memcpy(buf, in, count);
116 /* Finished? Re-register buffer so Host will use it again. */
124 * virtio console configuration. This supports:
127 static void virtcons_apply_config(struct virtio_device *dev)
131 if (virtio_has_feature(dev, VIRTIO_CONSOLE_F_SIZE)) {
132 dev->config->get(dev,
133 offsetof(struct virtio_console_config, cols),
134 &ws.ws_col, sizeof(u16));
135 dev->config->get(dev,
136 offsetof(struct virtio_console_config, rows),
137 &ws.ws_row, sizeof(u16));
143 * we support only one console, the hvc struct is a global var We set
144 * the configuration at this point, since we now have a tty
146 static int notifier_add_vio(struct hvc_struct *hp, int data)
148 hp->irq_requested = 1;
149 virtcons_apply_config(vdev);
154 static void notifier_del_vio(struct hvc_struct *hp, int data)
156 hp->irq_requested = 0;
159 static void hvc_handle_input(struct virtqueue *vq)
165 /* The operations for the console. */
166 static struct hv_ops hv_ops = {
167 .get_chars = get_chars,
168 .put_chars = put_chars,
169 .notifier_add = notifier_add_vio,
170 .notifier_del = notifier_del_vio,
171 .notifier_hangup = notifier_del_vio,
175 * Console drivers are initialized very early so boot messages can go
176 * out, so we do things slightly differently from the generic virtio
177 * initialization of the net and block drivers.
179 * At this stage, the console is output-only. It's too early to set
180 * up a virtqueue, so we let the drivers do some boutique early-output
183 int __init virtio_cons_early_init(int (*put_chars)(u32, const char *, int))
185 early_put_chars = put_chars;
186 return hvc_instantiate(0, 0, &hv_ops);
190 * Once we're further in boot, we get probed like any other virtio
191 * device. At this stage we set up the output virtqueue.
193 * To set up and manage our virtual console, we call hvc_alloc().
194 * Since we never remove the console device we never need this pointer
197 * Finally we put our input buffer in the input queue, ready to
200 static int __devinit virtcons_probe(struct virtio_device *dev)
202 vq_callback_t *callbacks[] = { hvc_handle_input, NULL};
203 const char *names[] = { "input", "output" };
204 struct virtqueue *vqs[2];
209 /* This is the scratch page we use to receive console input */
210 inbuf = kmalloc(PAGE_SIZE, GFP_KERNEL);
216 /* Find the queues. */
217 err = vdev->config->find_vqs(vdev, 2, vqs, callbacks, names);
225 * The first argument of hvc_alloc() is the virtual console
226 * number, so we use zero. The second argument is the
227 * parameter for the notification mechanism (like irq
228 * number). We currently leave this as zero, virtqueues have
229 * implicit notifications.
231 * The third argument is a "struct hv_ops" containing the
232 * put_chars(), get_chars(), notifier_add() and notifier_del()
233 * pointers. The final argument is the output buffer size: we
234 * can do any size, so we put PAGE_SIZE here.
236 hvc = hvc_alloc(0, 0, &hv_ops, PAGE_SIZE);
242 /* Register the input buffer the first time. */
245 /* Start using the new console output. */
246 early_put_chars = NULL;
250 vdev->config->del_vqs(vdev);
257 static struct virtio_device_id id_table[] = {
258 { VIRTIO_ID_CONSOLE, VIRTIO_DEV_ANY_ID },
262 static unsigned int features[] = {
263 VIRTIO_CONSOLE_F_SIZE,
266 static struct virtio_driver virtio_console = {
267 .feature_table = features,
268 .feature_table_size = ARRAY_SIZE(features),
269 .driver.name = KBUILD_MODNAME,
270 .driver.owner = THIS_MODULE,
271 .id_table = id_table,
272 .probe = virtcons_probe,
273 .config_changed = virtcons_apply_config,
276 static int __init init(void)
278 return register_virtio_driver(&virtio_console);
282 MODULE_DEVICE_TABLE(virtio, id_table);
283 MODULE_DESCRIPTION("Virtio console driver");
284 MODULE_LICENSE("GPL");