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a23ea924 RR |
1 | /* |
2 | * Copyright (C) 2006, 2007, 2009 Rusty Russell, IBM Corporation | |
31610434 RR |
3 | * |
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 | ||
31610434 RR |
24 | static struct virtqueue *in_vq, *out_vq; |
25 | static struct virtio_device *vdev; | |
26 | ||
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; | |
30 | ||
91fcad19 CB |
31 | /* The hvc device */ |
32 | static struct hvc_struct *hvc; | |
33 | ||
971f3390 RR |
34 | /* This is the very early arch-specified put chars function. */ |
35 | static int (*early_put_chars)(u32, const char *, int); | |
36 | ||
a23ea924 RR |
37 | /* |
38 | * The put_chars() callback is pretty straightforward. | |
31610434 | 39 | * |
a23ea924 RR |
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). | |
44 | */ | |
31610434 RR |
45 | static int put_chars(u32 vtermno, const char *buf, int count) |
46 | { | |
47 | struct scatterlist sg[1]; | |
48 | unsigned int len; | |
49 | ||
971f3390 RR |
50 | if (unlikely(early_put_chars)) |
51 | return early_put_chars(vtermno, buf, count); | |
52 | ||
31610434 RR |
53 | /* This is a convenient routine to initialize a single-elem sg list */ |
54 | sg_init_one(sg, buf, count); | |
55 | ||
a23ea924 RR |
56 | /* |
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. | |
59 | */ | |
3c1b27d5 | 60 | if (out_vq->vq_ops->add_buf(out_vq, sg, 1, 0, (void *)1) >= 0) { |
31610434 RR |
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)) | |
65 | cpu_relax(); | |
66 | } | |
67 | ||
68 | /* We're expected to return the amount of data we wrote: all of it. */ | |
69 | return count; | |
70 | } | |
71 | ||
a23ea924 RR |
72 | /* |
73 | * Create a scatter-gather list representing our input buffer and put | |
74 | * it in the queue. | |
75 | */ | |
31610434 RR |
76 | static void add_inbuf(void) |
77 | { | |
78 | struct scatterlist sg[1]; | |
79 | sg_init_one(sg, inbuf, PAGE_SIZE); | |
80 | ||
81 | /* We should always be able to add one buffer to an empty queue. */ | |
3c1b27d5 | 82 | if (in_vq->vq_ops->add_buf(in_vq, sg, 0, 1, inbuf) < 0) |
31610434 RR |
83 | BUG(); |
84 | in_vq->vq_ops->kick(in_vq); | |
85 | } | |
86 | ||
a23ea924 RR |
87 | /* |
88 | * get_chars() is the callback from the hvc_console infrastructure | |
89 | * when an interrupt is received. | |
31610434 | 90 | * |
a23ea924 RR |
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. | |
94 | */ | |
31610434 RR |
95 | static int get_chars(u32 vtermno, char *buf, int count) |
96 | { | |
97 | /* If we don't have an input queue yet, we can't get input. */ | |
98 | BUG_ON(!in_vq); | |
99 | ||
100 | /* No buffer? Try to get one. */ | |
101 | if (!in_len) { | |
102 | in = in_vq->vq_ops->get_buf(in_vq, &in_len); | |
103 | if (!in) | |
104 | return 0; | |
105 | } | |
106 | ||
107 | /* You want more than we have to give? Well, try wanting less! */ | |
108 | if (in_len < count) | |
109 | count = in_len; | |
110 | ||
111 | /* Copy across to their buffer and increment offset. */ | |
112 | memcpy(buf, in, count); | |
113 | in += count; | |
114 | in_len -= count; | |
115 | ||
116 | /* Finished? Re-register buffer so Host will use it again. */ | |
117 | if (in_len == 0) | |
118 | add_inbuf(); | |
119 | ||
120 | return count; | |
121 | } | |
31610434 | 122 | |
c2983458 CB |
123 | /* |
124 | * virtio console configuration. This supports: | |
125 | * - console resize | |
126 | */ | |
127 | static void virtcons_apply_config(struct virtio_device *dev) | |
128 | { | |
129 | struct winsize ws; | |
130 | ||
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)); | |
138 | hvc_resize(hvc, ws); | |
139 | } | |
140 | } | |
141 | ||
91fcad19 | 142 | /* |
a23ea924 RR |
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 | |
91fcad19 CB |
145 | */ |
146 | static int notifier_add_vio(struct hvc_struct *hp, int data) | |
147 | { | |
148 | hp->irq_requested = 1; | |
c2983458 CB |
149 | virtcons_apply_config(vdev); |
150 | ||
91fcad19 CB |
151 | return 0; |
152 | } | |
153 | ||
154 | static void notifier_del_vio(struct hvc_struct *hp, int data) | |
155 | { | |
156 | hp->irq_requested = 0; | |
157 | } | |
158 | ||
159 | static void hvc_handle_input(struct virtqueue *vq) | |
160 | { | |
161 | if (hvc_poll(hvc)) | |
162 | hvc_kick(); | |
163 | } | |
164 | ||
971f3390 | 165 | /* The operations for the console. */ |
1dff3996 | 166 | static const struct hv_ops hv_ops = { |
971f3390 RR |
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, | |
172 | }; | |
173 | ||
174 | /* | |
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. | |
178 | * | |
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 | |
181 | * thing. | |
182 | */ | |
183 | int __init virtio_cons_early_init(int (*put_chars)(u32, const char *, int)) | |
184 | { | |
185 | early_put_chars = put_chars; | |
186 | return hvc_instantiate(0, 0, &hv_ops); | |
187 | } | |
188 | ||
a23ea924 RR |
189 | /* |
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. | |
31610434 | 192 | * |
a23ea924 RR |
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 | |
195 | * again. | |
31610434 | 196 | * |
a23ea924 RR |
197 | * Finally we put our input buffer in the input queue, ready to |
198 | * receive. | |
199 | */ | |
139b8298 | 200 | static int __devinit virtcons_probe(struct virtio_device *dev) |
31610434 | 201 | { |
d2a7ddda MT |
202 | vq_callback_t *callbacks[] = { hvc_handle_input, NULL}; |
203 | const char *names[] = { "input", "output" }; | |
204 | struct virtqueue *vqs[2]; | |
31610434 | 205 | int err; |
31610434 RR |
206 | |
207 | vdev = dev; | |
208 | ||
209 | /* This is the scratch page we use to receive console input */ | |
210 | inbuf = kmalloc(PAGE_SIZE, GFP_KERNEL); | |
211 | if (!inbuf) { | |
212 | err = -ENOMEM; | |
213 | goto fail; | |
214 | } | |
215 | ||
d2a7ddda | 216 | /* Find the queues. */ |
d2a7ddda MT |
217 | err = vdev->config->find_vqs(vdev, 2, vqs, callbacks, names); |
218 | if (err) | |
31610434 | 219 | goto free; |
31610434 | 220 | |
d2a7ddda MT |
221 | in_vq = vqs[0]; |
222 | out_vq = vqs[1]; | |
31610434 | 223 | |
a23ea924 RR |
224 | /* |
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. | |
31610434 | 230 | * |
a23ea924 RR |
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. | |
235 | */ | |
971f3390 | 236 | hvc = hvc_alloc(0, 0, &hv_ops, PAGE_SIZE); |
31610434 RR |
237 | if (IS_ERR(hvc)) { |
238 | err = PTR_ERR(hvc); | |
d2a7ddda | 239 | goto free_vqs; |
31610434 RR |
240 | } |
241 | ||
242 | /* Register the input buffer the first time. */ | |
243 | add_inbuf(); | |
971f3390 RR |
244 | |
245 | /* Start using the new console output. */ | |
246 | early_put_chars = NULL; | |
31610434 RR |
247 | return 0; |
248 | ||
d2a7ddda MT |
249 | free_vqs: |
250 | vdev->config->del_vqs(vdev); | |
31610434 RR |
251 | free: |
252 | kfree(inbuf); | |
253 | fail: | |
254 | return err; | |
255 | } | |
256 | ||
257 | static struct virtio_device_id id_table[] = { | |
258 | { VIRTIO_ID_CONSOLE, VIRTIO_DEV_ANY_ID }, | |
259 | { 0 }, | |
260 | }; | |
261 | ||
c2983458 CB |
262 | static unsigned int features[] = { |
263 | VIRTIO_CONSOLE_F_SIZE, | |
264 | }; | |
265 | ||
31610434 | 266 | static struct virtio_driver virtio_console = { |
c2983458 CB |
267 | .feature_table = features, |
268 | .feature_table_size = ARRAY_SIZE(features), | |
31610434 RR |
269 | .driver.name = KBUILD_MODNAME, |
270 | .driver.owner = THIS_MODULE, | |
271 | .id_table = id_table, | |
272 | .probe = virtcons_probe, | |
c2983458 | 273 | .config_changed = virtcons_apply_config, |
31610434 RR |
274 | }; |
275 | ||
276 | static int __init init(void) | |
277 | { | |
278 | return register_virtio_driver(&virtio_console); | |
279 | } | |
280 | module_init(init); | |
281 | ||
282 | MODULE_DEVICE_TABLE(virtio, id_table); | |
283 | MODULE_DESCRIPTION("Virtio console driver"); | |
284 | MODULE_LICENSE("GPL"); |