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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>
This commit is contained in:
Rusty Russell 2010-01-18 19:14:55 +05:30
parent 3b8706240e
commit a23ea92474
2 changed files with 58 additions and 56 deletions
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108
drivers/char/virtio_console.c
View File

@ -1,18 +1,5 @@
/*D:300 /*
* The Guest console driver * Copyright (C) 2006, 2007, 2009 Rusty Russell, IBM Corporation
*
* Writing console drivers is one of the few remaining Dark Arts in Linux.
* Fortunately for us, the path of virtual consoles has been well-trodden by
* the PowerPC folks, who wrote "hvc_console.c" to generically support any
* virtual console. We use that infrastructure which only requires us to write
* the basic put_chars and get_chars functions and call the right register
* functions.
:*/
/*M:002 The console can be flooded: while the Guest is processing input the
* Host can send more. Buffering in the Host could alleviate this, but it is a
* difficult problem in general. :*/
/* Copyright (C) 2006, 2007 Rusty Russell, IBM Corporation
* *
* This program is free software; you can redistribute it and/or modify * This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by * it under the terms of the GNU General Public License as published by
@ -34,8 +21,6 @@
#include <linux/virtio_console.h> #include <linux/virtio_console.h>
#include "hvc_console.h" #include "hvc_console.h"
/*D:340 These represent our input and output console queues, and the virtio
* operations for them. */
static struct virtqueue *in_vq, *out_vq; static struct virtqueue *in_vq, *out_vq;
static struct virtio_device *vdev; static struct virtio_device *vdev;
@ -49,12 +34,14 @@ static struct hv_ops virtio_cons;
/* The hvc device */ /* The hvc device */
static struct hvc_struct *hvc; static struct hvc_struct *hvc;
/*D:310 The put_chars() callback is pretty straightforward. /*
* The put_chars() callback is pretty straightforward.
* *
* We turn the characters into a scatter-gather list, add it to the output * We turn the characters into a scatter-gather list, add it to the
* queue and then kick the Host. Then we sit here waiting for it to finish: * output queue and then kick the Host. Then we sit here waiting for
* inefficient in theory, but in practice implementations will do it * it to finish: inefficient in theory, but in practice
* immediately (lguest's Launcher does). */ * implementations will do it immediately (lguest's Launcher does).
*/
static int put_chars(u32 vtermno, const char *buf, int count) static int put_chars(u32 vtermno, const char *buf, int count)
{ {
struct scatterlist sg[1]; struct scatterlist sg[1];
@ -63,8 +50,10 @@ static int put_chars(u32 vtermno, const char *buf, int count)
/* This is a convenient routine to initialize a single-elem sg list */ /* This is a convenient routine to initialize a single-elem sg list */
sg_init_one(sg, buf, count); sg_init_one(sg, buf, count);
/* add_buf wants a token to identify this buffer: we hand it any /*
* non-NULL pointer, since there's only ever one buffer. */ * add_buf wants a token to identify this buffer: we hand it
* any non-NULL pointer, since there's only ever one buffer.
*/
if (out_vq->vq_ops->add_buf(out_vq, sg, 1, 0, (void *)1) >= 0) { if (out_vq->vq_ops->add_buf(out_vq, sg, 1, 0, (void *)1) >= 0) {
/* Tell Host to go! */ /* Tell Host to go! */
out_vq->vq_ops->kick(out_vq); out_vq->vq_ops->kick(out_vq);
@ -77,8 +66,10 @@ static int put_chars(u32 vtermno, const char *buf, int count)
return count; return count;
} }
/* Create a scatter-gather list representing our input buffer and put it in the /*
* queue. */ * Create a scatter-gather list representing our input buffer and put
* it in the queue.
*/
static void add_inbuf(void) static void add_inbuf(void)
{ {
struct scatterlist sg[1]; struct scatterlist sg[1];
@ -90,12 +81,14 @@ static void add_inbuf(void)
in_vq->vq_ops->kick(in_vq); in_vq->vq_ops->kick(in_vq);
} }
/*D:350 get_chars() is the callback from the hvc_console infrastructure when /*
* an interrupt is received. * get_chars() is the callback from the hvc_console infrastructure
* when an interrupt is received.
* *
* Most of the code deals with the fact that the hvc_console() infrastructure * Most of the code deals with the fact that the hvc_console()
* only asks us for 16 bytes at a time. We keep in_offset and in_used fields * infrastructure only asks us for 16 bytes at a time. We keep
* for partially-filled buffers. */ * in_offset and in_used fields for partially-filled buffers.
*/
static int get_chars(u32 vtermno, char *buf, int count) static int get_chars(u32 vtermno, char *buf, int count)
{ {
/* If we don't have an input queue yet, we can't get input. */ /* 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)
return count; return count;
} }
/*:*/
/*D:320 Console drivers are initialized very early so boot messages can go out, /*
* so we do things slightly differently from the generic virtio initialization * Console drivers are initialized very early so boot messages can go
* of the net and block drivers. * out, so we do things slightly differently from the generic virtio
* initialization of the net and block drivers.
* *
* At this stage, the console is output-only. It's too early to set up a * At this stage, the console is output-only. It's too early to set
* virtqueue, so we let the drivers do some boutique early-output thing. */ * up a virtqueue, so we let the drivers do some boutique early-output
* thing.
*/
int __init virtio_cons_early_init(int (*put_chars)(u32, const char *, int)) int __init virtio_cons_early_init(int (*put_chars)(u32, const char *, int))
{ {
virtio_cons.put_chars = put_chars; virtio_cons.put_chars = put_chars;
@ -157,8 +152,8 @@ static void virtcons_apply_config(struct virtio_device *dev)
} }
/* /*
* we support only one console, the hvc struct is a global var * we support only one console, the hvc struct is a global var We set
* We set the configuration at this point, since we now have a tty * the configuration at this point, since we now have a tty
*/ */
static int notifier_add_vio(struct hvc_struct *hp, int data) static int notifier_add_vio(struct hvc_struct *hp, int data)
{ {
@ -179,13 +174,17 @@ static void hvc_handle_input(struct virtqueue *vq)
hvc_kick(); hvc_kick();
} }
/*D:370 Once we're further in boot, we get probed like any other virtio device. /*
* At this stage we set up the output virtqueue. * Once we're further in boot, we get probed like any other virtio
* device. At this stage we set up the output virtqueue.
* *
* To set up and manage our virtual console, we call hvc_alloc(). Since we * To set up and manage our virtual console, we call hvc_alloc().
* never remove the console device we never need this pointer again. * Since we never remove the console device we never need this pointer
* again.
* *
* Finally we put our input buffer in the input queue, ready to receive. */ * Finally we put our input buffer in the input queue, ready to
* receive.
*/
static int __devinit virtcons_probe(struct virtio_device *dev) static int __devinit virtcons_probe(struct virtio_device *dev)
{ {
vq_callback_t *callbacks[] = { hvc_handle_input, NULL}; vq_callback_t *callbacks[] = { hvc_handle_input, NULL};
@ -203,8 +202,6 @@ static int __devinit virtcons_probe(struct virtio_device *dev)
} }
/* Find the queues. */ /* Find the queues. */
/* FIXME: This is why we want to wean off hvc: we do nothing
* when input comes in. */
err = vdev->config->find_vqs(vdev, 2, vqs, callbacks, names); err = vdev->config->find_vqs(vdev, 2, vqs, callbacks, names);
if (err) if (err)
goto free; goto free;
@ -219,15 +216,18 @@ static int __devinit virtcons_probe(struct virtio_device *dev)
virtio_cons.notifier_del = notifier_del_vio; virtio_cons.notifier_del = notifier_del_vio;
virtio_cons.notifier_hangup = notifier_del_vio; virtio_cons.notifier_hangup = notifier_del_vio;
/* The first argument of hvc_alloc() is the virtual console number, so /*
* we use zero. The second argument is the parameter for the * The first argument of hvc_alloc() is the virtual console
* notification mechanism (like irq number). We currently leave this * number, so we use zero. The second argument is the
* as zero, virtqueues have implicit notifications. * parameter for the notification mechanism (like irq
* number). We currently leave this as zero, virtqueues have
* implicit notifications.
* *
* The third argument is a "struct hv_ops" containing the put_chars() * The third argument is a "struct hv_ops" containing the
* get_chars(), notifier_add() and notifier_del() pointers. * put_chars(), get_chars(), notifier_add() and notifier_del()
* The final argument is the output buffer size: we can do any size, * pointers. The final argument is the output buffer size: we
* so we put PAGE_SIZE here. */ * can do any size, so we put PAGE_SIZE here.
*/
hvc = hvc_alloc(0, 0, &virtio_cons, PAGE_SIZE); hvc = hvc_alloc(0, 0, &virtio_cons, PAGE_SIZE);
if (IS_ERR(hvc)) { if (IS_ERR(hvc)) {
err = PTR_ERR(hvc); err = PTR_ERR(hvc);

6
include/linux/virtio_console.h
View File

@ -3,8 +3,10 @@
#include <linux/types.h> #include <linux/types.h>
#include <linux/virtio_ids.h> #include <linux/virtio_ids.h>
#include <linux/virtio_config.h> #include <linux/virtio_config.h>
/* This header, excluding the #ifdef __KERNEL__ part, is BSD licensed so /*
* anyone can use the definitions to implement compatible drivers/servers. */ * This header, excluding the #ifdef __KERNEL__ part, is BSD licensed so
* anyone can use the definitions to implement compatible drivers/servers.
*/
/* Feature bits */ /* Feature bits */
#define VIRTIO_CONSOLE_F_SIZE 0 /* Does host provide console size? */ #define VIRTIO_CONSOLE_F_SIZE 0 /* Does host provide console size? */