/* A simple block driver for lguest.
*
* Copyright 2006 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation
*
* 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
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
//#define DEBUG
#include <linux/init.h>
#include <linux/types.h>
#include <linux/blkdev.h>
#include <linux/interrupt.h>
#include <linux/lguest_bus.h>
static char next_block_index = 'a';
struct blockdev
{
spinlock_t lock;
/* The disk structure for the kernel. */
struct gendisk *disk;
/* The major number for this disk. */
int major;
int irq;
unsigned long phys_addr;
/* The mapped block page. */
struct lguest_block_page *lb_page;
/* We only have a single request outstanding at a time. */
struct lguest_dma dma;
struct request *req;
};
/* Jens gave me this nice helper to end all chunks of a request. */
static void end_entire_request(struct request *req, int uptodate)
{
if (end_that_request_first(req, uptodate, req->hard_nr_sectors))
BUG();
add_disk_randomness(req->rq_disk);
blkdev_dequeue_request(req);
end_that_request_last(req, uptodate);
}
static irqreturn_t lgb_irq(int irq, void *_bd)
{
struct blockdev *bd = _bd;
unsigned long flags;
if (!bd->req) {
pr_debug("No work!\n");
return IRQ_NONE;
}
if (!bd->lb_page->result) {
pr_debug("No result!\n");
return IRQ_NONE;
}
spin_lock_irqsave(&bd->lock, flags);
end_entire_request(bd->req, bd->lb_page->result == 1);
bd->req = NULL;
bd->dma.used_len = 0;
blk_start_queue(bd->disk->queue);
spin_unlock_irqrestore(&bd->lock, flags);
return IRQ_HANDLED;
}
static unsigned int req_to_dma(struct request *req, struct lguest_dma *dma)
{
unsigned int i = 0, idx, len = 0;
struct bio *bio;
rq_for_each_bio(bio, req) {
struct bio_vec *bvec;
bio_for_each_segment(bvec, bio, idx) {
BUG_ON(i == LGUEST_MAX_DMA_SECTIONS);
BUG_ON(!bvec->bv_len);
dma->addr[i] = page_to_phys(bvec->bv_page)
+ bvec->bv_offset;
dma->len[i] = bvec->bv_len;
len += bvec->bv_len;
i++;
}
}
if (i < LGUEST_MAX_DMA_SECTIONS)
dma->len[i] = 0;
return len;
}
static void empty_dma(struct lguest_dma *dma)
{
dma->len[0] = 0;
}
static void setup_req(struct blockdev *bd,
int type, struct request *req, struct lguest_dma *dma)
{
bd->lb_page->type = type;
bd->lb_page->sector = req->sector;
bd->lb_page->result = 0;
bd->req = req;
bd->lb_page->bytes = req_to_dma(req, dma);
}
static void do_write(struct blockdev *bd, struct request *req)
{
struct lguest_dma send;
pr_debug("lgb: WRITE sector %li\n", (long)req->sector);
setup_req(bd, 1, req, &send);
lguest_send_dma(bd->phys_addr, &send);
}
static void do_read(struct blockdev *bd, struct request *req)
{
struct lguest_dma ping;
pr_debug("lgb: READ sector %li\n", (long)req->sector);
setup_req(bd, 0, req, &bd->dma);
empty_dma(&ping);
lguest_send_dma(bd->phys_addr, &ping);
}
static void do_lgb_request(request_queue_t *q)
{
struct blockdev *bd;
struct request *req;
again:
req = elv_next_request(q);
if (!req)
return;
bd = req->rq_disk->private_data;
/* Sometimes we get repeated requests after blk_stop_queue. */
if (bd->req)
return;
if (!blk_fs_request(req)) {
pr_debug("Got non-command 0x%08x\n", req->cmd_type);
req->errors++;
end_entire_request(req, 0);
goto again;
}
if (rq_data_dir(req) == WRITE)
do_write(bd, req);
else
do_read(bd, req);
/* Wait for interrupt to tell us it's done. */
blk_stop_queue(q);
}
static struct block_device_operations lguestblk_fops = {
.owner = THIS_MODULE,
};
static int lguestblk_probe(struct lguest_device *lgdev)
{
struct blockdev *bd;
int err;
int irqflags = IRQF_SHARED;
bd = kmalloc(sizeof(*bd), GFP_KERNEL);
if (!bd)
return -ENOMEM;
spin_lock_init(&bd->lock);
bd->irq = lgdev_irq(lgdev);
bd->req = NULL;
bd->dma.used_len = 0;
bd->dma.len[0] = 0;
bd->phys_addr = (lguest_devices[lgdev->index].pfn << PAGE_SHIFT);
bd->lb_page = lguest_map(bd->phys_addr, 1);
if (!bd->lb_page) {
err = -ENOMEM;
goto out_free_bd;
}
bd->major = register_blkdev(0, "lguestblk");
if (bd->major < 0) {
err = bd->major;
goto out_unmap;
}
bd->disk = alloc_disk(1);
if (!bd->disk) {
err = -ENOMEM;
goto out_unregister_blkdev;
}
bd->disk->queue = blk_init_queue(do_lgb_request, &bd->lock);
if (!bd->disk->queue) {
err = -ENOMEM;
goto out_put_disk;
}
/* We can only handle a certain number of sg entries */
blk_queue_max_hw_segments(bd->disk->queue, LGUEST_MAX_DMA_SECTIONS);
/* Buffers must not cross page boundaries */
blk_queue_segment_boundary(bd->disk->queue, PAGE_SIZE-1);
sprintf(bd->disk->disk_name, "lgb%c", next_block_index++);
if (lguest_devices[lgdev->index].features & LGUEST_DEVICE_F_RANDOMNESS)
irqflags |= IRQF_SAMPLE_RANDOM;
err = request_irq(bd->irq, lgb_irq, irqflags, bd->disk->disk_name, bd);
if (err)
goto out_cleanup_queue;
err = lguest_bind_dma(bd->phys_addr, &bd->dma, 1, bd->irq);
if (err)
goto out_free_irq;
bd->disk->major = bd->major;
bd->disk->first_minor = 0;
bd->disk->private_data = bd;
bd->disk->fops = &lguestblk_fops;
/* This is initialized to the disk size by the other end. */
set_capacity(bd->disk, bd->lb_page->num_sectors);
add_disk(bd->disk);
printk(KERN_INFO "%s: device %i at major %d\n",
bd->disk->disk_name, lgdev->index, bd->major);
lgdev->private = bd;
return 0;
out_free_irq:
free_irq(bd->irq, bd);
out_cleanup_queue:
blk_cleanup_queue(bd->disk->queue);
out_put_disk:
put_disk(bd->disk);
out_unregister_blkdev:
unregister_blkdev(bd->major, "lguestblk");
out_unmap:
lguest_unmap(bd->lb_page);
out_free_bd:
kfree(bd);
return err;
}
static struct lguest_driver lguestblk_drv = {
.name = "lguestblk",
.owner = THIS_MODULE,
.device_type = LGUEST_DEVICE_T_BLOCK,
.probe = lguestblk_probe,
};
static __init int lguestblk_init(void)
{
return register_lguest_driver(&lguestblk_drv);
}
module_init(lguestblk_init);
MODULE_DESCRIPTION("Lguest block driver");
MODULE_LICENSE("GPL");
