diff options
Diffstat (limited to 'drivers/block/lguest_blk.c')
| -rw-r--r-- | drivers/block/lguest_blk.c | 275 |
1 files changed, 275 insertions, 0 deletions
diff --git a/drivers/block/lguest_blk.c b/drivers/block/lguest_blk.c new file mode 100644 index 00000000000..1634c2dd25e --- /dev/null +++ b/drivers/block/lguest_blk.c @@ -0,0 +1,275 @@ +/* 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"); |