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authorRusty Russell <rusty@rustcorp.com.au>2010-01-18 08:44:55 -0500
committerRusty Russell <rusty@rustcorp.com.au>2010-02-23 22:52:30 -0500
commita23ea92474e558b071d3e43d961ec767c31faebd (patch)
treebb95ff6c72488e19fb624e3ee00263bcf66ac52c /drivers/char
parent3b8706240ee6084ccb46e53cd3a554356b7eeec8 (diff)
virtio: console: comment cleanup
Remove old lguest-style comments. [Amit: - wingify comments acc. to kernel style - indent comments ] Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Amit Shah <amit.shah@redhat.com> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'drivers/char')
-rw-r--r--drivers/char/virtio_console.c108
1 files changed, 54 insertions, 54 deletions
diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
index a035ae39a359..26e238cd7d2f 100644
--- a/drivers/char/virtio_console.c
+++ b/drivers/char/virtio_console.c
@@ -1,18 +1,5 @@
1/*D:300 1/*
2 * The Guest console driver 2 * Copyright (C) 2006, 2007, 2009 Rusty Russell, IBM Corporation
3 *
4 * Writing console drivers is one of the few remaining Dark Arts in Linux.
5 * Fortunately for us, the path of virtual consoles has been well-trodden by
6 * the PowerPC folks, who wrote "hvc_console.c" to generically support any
7 * virtual console. We use that infrastructure which only requires us to write
8 * the basic put_chars and get_chars functions and call the right register
9 * functions.
10 :*/
11
12/*M:002 The console can be flooded: while the Guest is processing input the
13 * Host can send more. Buffering in the Host could alleviate this, but it is a
14 * difficult problem in general. :*/
15/* Copyright (C) 2006, 2007 Rusty Russell, IBM Corporation
16 * 3 *
17 * This program is free software; you can redistribute it and/or modify 4 * This program is free software; you can redistribute it and/or modify
18 * it under the terms of the GNU General Public License as published by 5 * it under the terms of the GNU General Public License as published by
@@ -34,8 +21,6 @@
34#include <linux/virtio_console.h> 21#include <linux/virtio_console.h>
35#include "hvc_console.h" 22#include "hvc_console.h"
36 23
37/*D:340 These represent our input and output console queues, and the virtio
38 * operations for them. */
39static struct virtqueue *in_vq, *out_vq; 24static struct virtqueue *in_vq, *out_vq;
40static struct virtio_device *vdev; 25static struct virtio_device *vdev;
41 26
@@ -49,12 +34,14 @@ static struct hv_ops virtio_cons;
49/* The hvc device */ 34/* The hvc device */
50static struct hvc_struct *hvc; 35static struct hvc_struct *hvc;
51 36
52/*D:310 The put_chars() callback is pretty straightforward. 37/*
38 * The put_chars() callback is pretty straightforward.
53 * 39 *
54 * We turn the characters into a scatter-gather list, add it to the output 40 * We turn the characters into a scatter-gather list, add it to the
55 * queue and then kick the Host. Then we sit here waiting for it to finish: 41 * output queue and then kick the Host. Then we sit here waiting for
56 * inefficient in theory, but in practice implementations will do it 42 * it to finish: inefficient in theory, but in practice
57 * immediately (lguest's Launcher does). */ 43 * implementations will do it immediately (lguest's Launcher does).
44 */
58static int put_chars(u32 vtermno, const char *buf, int count) 45static int put_chars(u32 vtermno, const char *buf, int count)
59{ 46{
60 struct scatterlist sg[1]; 47 struct scatterlist sg[1];
@@ -63,8 +50,10 @@ static int put_chars(u32 vtermno, const char *buf, int count)
63 /* This is a convenient routine to initialize a single-elem sg list */ 50 /* This is a convenient routine to initialize a single-elem sg list */
64 sg_init_one(sg, buf, count); 51 sg_init_one(sg, buf, count);
65 52
66 /* add_buf wants a token to identify this buffer: we hand it any 53 /*
67 * non-NULL pointer, since there's only ever one buffer. */ 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 */
68 if (out_vq->vq_ops->add_buf(out_vq, sg, 1, 0, (void *)1) >= 0) { 57 if (out_vq->vq_ops->add_buf(out_vq, sg, 1, 0, (void *)1) >= 0) {
69 /* Tell Host to go! */ 58 /* Tell Host to go! */
70 out_vq->vq_ops->kick(out_vq); 59 out_vq->vq_ops->kick(out_vq);
@@ -77,8 +66,10 @@ static int put_chars(u32 vtermno, const char *buf, int count)
77 return count; 66 return count;
78} 67}
79 68
80/* Create a scatter-gather list representing our input buffer and put it in the 69/*
81 * queue. */ 70 * Create a scatter-gather list representing our input buffer and put
71 * it in the queue.
72 */
82static void add_inbuf(void) 73static void add_inbuf(void)
83{ 74{
84 struct scatterlist sg[1]; 75 struct scatterlist sg[1];
@@ -90,12 +81,14 @@ static void add_inbuf(void)
90 in_vq->vq_ops->kick(in_vq); 81 in_vq->vq_ops->kick(in_vq);
91} 82}
92 83
93/*D:350 get_chars() is the callback from the hvc_console infrastructure when 84/*
94 * an interrupt is received. 85 * get_chars() is the callback from the hvc_console infrastructure
86 * when an interrupt is received.
95 * 87 *
96 * Most of the code deals with the fact that the hvc_console() infrastructure 88 * Most of the code deals with the fact that the hvc_console()
97 * only asks us for 16 bytes at a time. We keep in_offset and in_used fields 89 * infrastructure only asks us for 16 bytes at a time. We keep
98 * for partially-filled buffers. */ 90 * in_offset and in_used fields for partially-filled buffers.
91 */
99static int get_chars(u32 vtermno, char *buf, int count) 92static int get_chars(u32 vtermno, char *buf, int count)
100{ 93{
101 /* If we don't have an input queue yet, we can't get input. */ 94 /* If we don't have an input queue yet, we can't get input. */
@@ -123,14 +116,16 @@ static int get_chars(u32 vtermno, char *buf, int count)
123 116
124 return count; 117 return count;
125} 118}
126/*:*/
127 119
128/*D:320 Console drivers are initialized very early so boot messages can go out, 120/*
129 * so we do things slightly differently from the generic virtio initialization 121 * Console drivers are initialized very early so boot messages can go
130 * of the net and block drivers. 122 * out, so we do things slightly differently from the generic virtio
123 * initialization of the net and block drivers.
131 * 124 *
132 * At this stage, the console is output-only. It's too early to set up a 125 * At this stage, the console is output-only. It's too early to set
133 * virtqueue, so we let the drivers do some boutique early-output thing. */ 126 * up a virtqueue, so we let the drivers do some boutique early-output
127 * thing.
128 */
134int __init virtio_cons_early_init(int (*put_chars)(u32, const char *, int)) 129int __init virtio_cons_early_init(int (*put_chars)(u32, const char *, int))
135{ 130{
136 virtio_cons.put_chars = put_chars; 131 virtio_cons.put_chars = put_chars;
@@ -157,8 +152,8 @@ static void virtcons_apply_config(struct virtio_device *dev)
157} 152}
158 153
159/* 154/*
160 * we support only one console, the hvc struct is a global var 155 * we support only one console, the hvc struct is a global var We set
161 * We set the configuration at this point, since we now have a tty 156 * the configuration at this point, since we now have a tty
162 */ 157 */
163static int notifier_add_vio(struct hvc_struct *hp, int data) 158static int notifier_add_vio(struct hvc_struct *hp, int data)
164{ 159{
@@ -179,13 +174,17 @@ static void hvc_handle_input(struct virtqueue *vq)
179 hvc_kick(); 174 hvc_kick();
180} 175}
181 176
182/*D:370 Once we're further in boot, we get probed like any other virtio device. 177/*
183 * At this stage we set up the output virtqueue. 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.
184 * 180 *
185 * To set up and manage our virtual console, we call hvc_alloc(). Since we 181 * To set up and manage our virtual console, we call hvc_alloc().
186 * never remove the console device we never need this pointer again. 182 * Since we never remove the console device we never need this pointer
183 * again.
187 * 184 *
188 * Finally we put our input buffer in the input queue, ready to receive. */ 185 * Finally we put our input buffer in the input queue, ready to
186 * receive.
187 */
189static int __devinit virtcons_probe(struct virtio_device *dev) 188static int __devinit virtcons_probe(struct virtio_device *dev)
190{ 189{
191 vq_callback_t *callbacks[] = { hvc_handle_input, NULL}; 190 vq_callback_t *callbacks[] = { hvc_handle_input, NULL};
@@ -203,8 +202,6 @@ static int __devinit virtcons_probe(struct virtio_device *dev)
203 } 202 }
204 203
205 /* Find the queues. */ 204 /* Find the queues. */
206 /* FIXME: This is why we want to wean off hvc: we do nothing
207 * when input comes in. */
208 err = vdev->config->find_vqs(vdev, 2, vqs, callbacks, names); 205 err = vdev->config->find_vqs(vdev, 2, vqs, callbacks, names);
209 if (err) 206 if (err)
210 goto free; 207 goto free;
@@ -219,15 +216,18 @@ static int __devinit virtcons_probe(struct virtio_device *dev)
219 virtio_cons.notifier_del = notifier_del_vio; 216 virtio_cons.notifier_del = notifier_del_vio;
220 virtio_cons.notifier_hangup = notifier_del_vio; 217 virtio_cons.notifier_hangup = notifier_del_vio;
221 218
222 /* The first argument of hvc_alloc() is the virtual console number, so 219 /*
223 * we use zero. The second argument is the parameter for the 220 * The first argument of hvc_alloc() is the virtual console
224 * notification mechanism (like irq number). We currently leave this 221 * number, so we use zero. The second argument is the
225 * as zero, virtqueues have implicit notifications. 222 * parameter for the notification mechanism (like irq
223 * number). We currently leave this as zero, virtqueues have
224 * implicit notifications.
226 * 225 *
227 * The third argument is a "struct hv_ops" containing the put_chars() 226 * The third argument is a "struct hv_ops" containing the
228 * get_chars(), notifier_add() and notifier_del() pointers. 227 * put_chars(), get_chars(), notifier_add() and notifier_del()
229 * The final argument is the output buffer size: we can do any size, 228 * pointers. The final argument is the output buffer size: we
230 * so we put PAGE_SIZE here. */ 229 * can do any size, so we put PAGE_SIZE here.
230 */
231 hvc = hvc_alloc(0, 0, &virtio_cons, PAGE_SIZE); 231 hvc = hvc_alloc(0, 0, &virtio_cons, PAGE_SIZE);
232 if (IS_ERR(hvc)) { 232 if (IS_ERR(hvc)) {
233 err = PTR_ERR(hvc); 233 err = PTR_ERR(hvc);