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Rusty Russella23ea922010-01-18 19:14:55 +05301/*
2 * Copyright (C) 2006, 2007, 2009 Rusty Russell, IBM Corporation
Rusty Russell31610432007-10-22 11:03:39 +10003 *
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.
8 *
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.
13 *
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
17 */
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"
23
Rusty Russell31610432007-10-22 11:03:39 +100024static struct virtqueue *in_vq, *out_vq;
25static struct virtio_device *vdev;
26
27/* This is our input buffer, and how much data is left in it. */
28static unsigned int in_len;
29static char *in, *inbuf;
30
31/* The operations for our console. */
32static struct hv_ops virtio_cons;
33
Christian Borntraeger91fcad12008-06-20 15:24:15 +020034/* The hvc device */
35static struct hvc_struct *hvc;
36
Rusty Russella23ea922010-01-18 19:14:55 +053037/*
38 * The put_chars() callback is pretty straightforward.
Rusty Russell31610432007-10-22 11:03:39 +100039 *
Rusty Russella23ea922010-01-18 19:14:55 +053040 * 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).
44 */
Rusty Russell31610432007-10-22 11:03:39 +100045static int put_chars(u32 vtermno, const char *buf, int count)
46{
47 struct scatterlist sg[1];
48 unsigned int len;
49
50 /* This is a convenient routine to initialize a single-elem sg list */
51 sg_init_one(sg, buf, count);
52
Rusty Russella23ea922010-01-18 19:14:55 +053053 /*
54 * add_buf wants a token to identify this buffer: we hand it
55 * any non-NULL pointer, since there's only ever one buffer.
56 */
Rusty Russell3c1b27d2009-09-23 22:26:31 -060057 if (out_vq->vq_ops->add_buf(out_vq, sg, 1, 0, (void *)1) >= 0) {
Rusty Russell31610432007-10-22 11:03:39 +100058 /* Tell Host to go! */
59 out_vq->vq_ops->kick(out_vq);
60 /* Chill out until it's done with the buffer. */
61 while (!out_vq->vq_ops->get_buf(out_vq, &len))
62 cpu_relax();
63 }
64
65 /* We're expected to return the amount of data we wrote: all of it. */
66 return count;
67}
68
Rusty Russella23ea922010-01-18 19:14:55 +053069/*
70 * Create a scatter-gather list representing our input buffer and put
71 * it in the queue.
72 */
Rusty Russell31610432007-10-22 11:03:39 +100073static void add_inbuf(void)
74{
75 struct scatterlist sg[1];
76 sg_init_one(sg, inbuf, PAGE_SIZE);
77
78 /* We should always be able to add one buffer to an empty queue. */
Rusty Russell3c1b27d2009-09-23 22:26:31 -060079 if (in_vq->vq_ops->add_buf(in_vq, sg, 0, 1, inbuf) < 0)
Rusty Russell31610432007-10-22 11:03:39 +100080 BUG();
81 in_vq->vq_ops->kick(in_vq);
82}
83
Rusty Russella23ea922010-01-18 19:14:55 +053084/*
85 * get_chars() is the callback from the hvc_console infrastructure
86 * when an interrupt is received.
Rusty Russell31610432007-10-22 11:03:39 +100087 *
Rusty Russella23ea922010-01-18 19:14:55 +053088 * Most of the code deals with the fact that the hvc_console()
89 * infrastructure only asks us for 16 bytes at a time. We keep
90 * in_offset and in_used fields for partially-filled buffers.
91 */
Rusty Russell31610432007-10-22 11:03:39 +100092static int get_chars(u32 vtermno, char *buf, int count)
93{
94 /* If we don't have an input queue yet, we can't get input. */
95 BUG_ON(!in_vq);
96
97 /* No buffer? Try to get one. */
98 if (!in_len) {
99 in = in_vq->vq_ops->get_buf(in_vq, &in_len);
100 if (!in)
101 return 0;
102 }
103
104 /* You want more than we have to give? Well, try wanting less! */
105 if (in_len < count)
106 count = in_len;
107
108 /* Copy across to their buffer and increment offset. */
109 memcpy(buf, in, count);
110 in += count;
111 in_len -= count;
112
113 /* Finished? Re-register buffer so Host will use it again. */
114 if (in_len == 0)
115 add_inbuf();
116
117 return count;
118}
Rusty Russell31610432007-10-22 11:03:39 +1000119
Rusty Russella23ea922010-01-18 19:14:55 +0530120/*
121 * Console drivers are initialized very early so boot messages can go
122 * out, so we do things slightly differently from the generic virtio
123 * initialization of the net and block drivers.
Rusty Russell31610432007-10-22 11:03:39 +1000124 *
Rusty Russella23ea922010-01-18 19:14:55 +0530125 * At this stage, the console is output-only. It's too early to set
126 * up a virtqueue, so we let the drivers do some boutique early-output
127 * thing.
128 */
Rusty Russell31610432007-10-22 11:03:39 +1000129int __init virtio_cons_early_init(int (*put_chars)(u32, const char *, int))
130{
131 virtio_cons.put_chars = put_chars;
132 return hvc_instantiate(0, 0, &virtio_cons);
133}
134
Christian Borntraeger91fcad12008-06-20 15:24:15 +0200135/*
Christian Borntraegerc2983452008-11-25 13:36:26 +0100136 * virtio console configuration. This supports:
137 * - console resize
138 */
139static void virtcons_apply_config(struct virtio_device *dev)
140{
141 struct winsize ws;
142
143 if (virtio_has_feature(dev, VIRTIO_CONSOLE_F_SIZE)) {
144 dev->config->get(dev,
145 offsetof(struct virtio_console_config, cols),
146 &ws.ws_col, sizeof(u16));
147 dev->config->get(dev,
148 offsetof(struct virtio_console_config, rows),
149 &ws.ws_row, sizeof(u16));
150 hvc_resize(hvc, ws);
151 }
152}
153
154/*
Rusty Russella23ea922010-01-18 19:14:55 +0530155 * we support only one console, the hvc struct is a global var We set
156 * the configuration at this point, since we now have a tty
Christian Borntraeger91fcad12008-06-20 15:24:15 +0200157 */
158static int notifier_add_vio(struct hvc_struct *hp, int data)
159{
160 hp->irq_requested = 1;
Christian Borntraegerc2983452008-11-25 13:36:26 +0100161 virtcons_apply_config(vdev);
162
Christian Borntraeger91fcad12008-06-20 15:24:15 +0200163 return 0;
164}
165
166static void notifier_del_vio(struct hvc_struct *hp, int data)
167{
168 hp->irq_requested = 0;
169}
170
171static void hvc_handle_input(struct virtqueue *vq)
172{
173 if (hvc_poll(hvc))
174 hvc_kick();
175}
176
Rusty Russella23ea922010-01-18 19:14:55 +0530177/*
178 * Once we're further in boot, we get probed like any other virtio
179 * device. At this stage we set up the output virtqueue.
Rusty Russell31610432007-10-22 11:03:39 +1000180 *
Rusty Russella23ea922010-01-18 19:14:55 +0530181 * To set up and manage our virtual console, we call hvc_alloc().
182 * Since we never remove the console device we never need this pointer
183 * again.
Rusty Russell31610432007-10-22 11:03:39 +1000184 *
Rusty Russella23ea922010-01-18 19:14:55 +0530185 * Finally we put our input buffer in the input queue, ready to
186 * receive.
187 */
Randy Dunlap139b8292007-11-05 14:51:01 -0800188static int __devinit virtcons_probe(struct virtio_device *dev)
Rusty Russell31610432007-10-22 11:03:39 +1000189{
Michael S. Tsirkind2a7ddd2009-06-12 22:16:36 -0600190 vq_callback_t *callbacks[] = { hvc_handle_input, NULL};
191 const char *names[] = { "input", "output" };
192 struct virtqueue *vqs[2];
Rusty Russell31610432007-10-22 11:03:39 +1000193 int err;
Rusty Russell31610432007-10-22 11:03:39 +1000194
195 vdev = dev;
196
197 /* This is the scratch page we use to receive console input */
198 inbuf = kmalloc(PAGE_SIZE, GFP_KERNEL);
199 if (!inbuf) {
200 err = -ENOMEM;
201 goto fail;
202 }
203
Michael S. Tsirkind2a7ddd2009-06-12 22:16:36 -0600204 /* Find the queues. */
Michael S. Tsirkind2a7ddd2009-06-12 22:16:36 -0600205 err = vdev->config->find_vqs(vdev, 2, vqs, callbacks, names);
206 if (err)
Rusty Russell31610432007-10-22 11:03:39 +1000207 goto free;
Rusty Russell31610432007-10-22 11:03:39 +1000208
Michael S. Tsirkind2a7ddd2009-06-12 22:16:36 -0600209 in_vq = vqs[0];
210 out_vq = vqs[1];
Rusty Russell31610432007-10-22 11:03:39 +1000211
212 /* Start using the new console output. */
213 virtio_cons.get_chars = get_chars;
214 virtio_cons.put_chars = put_chars;
Christian Borntraeger91fcad12008-06-20 15:24:15 +0200215 virtio_cons.notifier_add = notifier_add_vio;
216 virtio_cons.notifier_del = notifier_del_vio;
Hendrik Bruecknerfc362e22008-10-13 23:12:48 +0000217 virtio_cons.notifier_hangup = notifier_del_vio;
Rusty Russell31610432007-10-22 11:03:39 +1000218
Rusty Russella23ea922010-01-18 19:14:55 +0530219 /*
220 * The first argument of hvc_alloc() is the virtual console
221 * number, so we use zero. The second argument is the
222 * parameter for the notification mechanism (like irq
223 * number). We currently leave this as zero, virtqueues have
224 * implicit notifications.
Rusty Russell31610432007-10-22 11:03:39 +1000225 *
Rusty Russella23ea922010-01-18 19:14:55 +0530226 * The third argument is a "struct hv_ops" containing the
227 * put_chars(), get_chars(), notifier_add() and notifier_del()
228 * pointers. The final argument is the output buffer size: we
229 * can do any size, so we put PAGE_SIZE here.
230 */
Rusty Russell31610432007-10-22 11:03:39 +1000231 hvc = hvc_alloc(0, 0, &virtio_cons, PAGE_SIZE);
232 if (IS_ERR(hvc)) {
233 err = PTR_ERR(hvc);
Michael S. Tsirkind2a7ddd2009-06-12 22:16:36 -0600234 goto free_vqs;
Rusty Russell31610432007-10-22 11:03:39 +1000235 }
236
237 /* Register the input buffer the first time. */
238 add_inbuf();
239 return 0;
240
Michael S. Tsirkind2a7ddd2009-06-12 22:16:36 -0600241free_vqs:
242 vdev->config->del_vqs(vdev);
Rusty Russell31610432007-10-22 11:03:39 +1000243free:
244 kfree(inbuf);
245fail:
246 return err;
247}
248
249static struct virtio_device_id id_table[] = {
250 { VIRTIO_ID_CONSOLE, VIRTIO_DEV_ANY_ID },
251 { 0 },
252};
253
Christian Borntraegerc2983452008-11-25 13:36:26 +0100254static unsigned int features[] = {
255 VIRTIO_CONSOLE_F_SIZE,
256};
257
Rusty Russell31610432007-10-22 11:03:39 +1000258static struct virtio_driver virtio_console = {
Christian Borntraegerc2983452008-11-25 13:36:26 +0100259 .feature_table = features,
260 .feature_table_size = ARRAY_SIZE(features),
Rusty Russell31610432007-10-22 11:03:39 +1000261 .driver.name = KBUILD_MODNAME,
262 .driver.owner = THIS_MODULE,
263 .id_table = id_table,
264 .probe = virtcons_probe,
Christian Borntraegerc2983452008-11-25 13:36:26 +0100265 .config_changed = virtcons_apply_config,
Rusty Russell31610432007-10-22 11:03:39 +1000266};
267
268static int __init init(void)
269{
270 return register_virtio_driver(&virtio_console);
271}
272module_init(init);
273
274MODULE_DEVICE_TABLE(virtio, id_table);
275MODULE_DESCRIPTION("Virtio console driver");
276MODULE_LICENSE("GPL");