path: root/drivers/scsi/xen-scsifront.c

/*
 * Xen SCSI frontend driver
 *
 * Copyright (c) 2008, FUJITSU Limited
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License version 2
 * as published by the Free Software Foundation; or, when distributed
 * separately from the Linux kernel or incorporated into other
 * software packages, subject to the following license:
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this source file (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use, copy, modify,
 * merge, publish, distribute, sublicense, and/or sell copies of the Software,
 * and to permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/device.h>
#include <linux/wait.h>
#include <linux/interrupt.h>
#include <linux/mutex.h>
#include <linux/spinlock.h>
#include <linux/sched.h>
#include <linux/blkdev.h>
#include <linux/pfn.h>
#include <linux/slab.h>
#include <linux/bitops.h>

#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi.h>
#include <scsi/scsi_host.h>

#include <xen/xen.h>
#include <xen/xenbus.h>
#include <xen/grant_table.h>
#include <xen/events.h>
#include <xen/page.h>

#include <xen/interface/grant_table.h>
#include <xen/interface/io/vscsiif.h>
#include <xen/interface/io/protocols.h>

#include <asm/xen/hypervisor.h>

#define VSCSIFRONT_OP_ADD_LUN	1
#define VSCSIFRONT_OP_DEL_LUN	2
#define VSCSIFRONT_OP_READD_LUN	3

/* Tuning point. */
#define VSCSIIF_DEFAULT_CMD_PER_LUN 10
#define VSCSIIF_MAX_TARGET          64
#define VSCSIIF_MAX_LUN             255

#define VSCSIIF_RING_SIZE	__CONST_RING_SIZE(vscsiif, PAGE_SIZE)
#define VSCSIIF_MAX_REQS	VSCSIIF_RING_SIZE

#define vscsiif_grants_sg(_sg)	(PFN_UP((_sg) *		\
				sizeof(struct scsiif_request_segment)))

struct vscsifrnt_shadow {
	/* command between backend and frontend */
	unsigned char act;
	uint8_t nr_segments;
	uint16_t rqid;
	uint16_t ref_rqid;

	bool inflight;

	unsigned int nr_grants;		/* number of grants in gref[] */
	struct scsiif_request_segment *sg;	/* scatter/gather elements */
	struct scsiif_request_segment seg[VSCSIIF_SG_TABLESIZE];

	/* Do reset or abort function. */
	wait_queue_head_t wq_reset;	/* reset work queue           */
	int wait_reset;			/* reset work queue condition */
	int32_t rslt_reset;		/* reset response status:     */
					/* SUCCESS or FAILED or:      */
#define RSLT_RESET_WAITING	0
#define RSLT_RESET_ERR		-1

	/* Requested struct scsi_cmnd is stored from kernel. */
	struct scsi_cmnd *sc;
	int gref[vscsiif_grants_sg(SG_ALL) + SG_ALL];
};

struct vscsifrnt_info {
	struct xenbus_device *dev;

	struct Scsi_Host *host;
	enum {
		STATE_INACTIVE,
		STATE_ACTIVE,
		STATE_ERROR
	}  host_active;

	unsigned int evtchn;
	unsigned int irq;

	grant_ref_t ring_ref;
	struct vscsiif_front_ring ring;
	struct vscsiif_response	ring_rsp;

	spinlock_t shadow_lock;
	DECLARE_BITMAP(shadow_free_bitmap, VSCSIIF_MAX_REQS);
	struct vscsifrnt_shadow *shadow[VSCSIIF_MAX_REQS];

	/* Following items are protected by the host lock. */
	wait_queue_head_t wq_sync;
	wait_queue_head_t wq_pause;
	unsigned int wait_ring_available:1;
	unsigned int waiting_pause:1;
	unsigned int pause:1;
	unsigned callers;

	char dev_state_path[64];
	struct task_struct *curr;
};

static DEFINE_MUTEX(scsifront_mutex);

static void scsifront_wake_up(struct vscsifrnt_info *info)
{
	info->wait_ring_available = 0;
	wake_up(&info->wq_sync);
}

static int scsifront_get_rqid(struct vscsifrnt_info *info)
{
	unsigned long flags;
	int free;

	spin_lock_irqsave(&info->shadow_lock, flags);

	free = find_first_bit(info->shadow_free_bitmap, VSCSIIF_MAX_REQS);
	__clear_bit(free, info->shadow_free_bitmap);

	spin_unlock_irqrestore(&info->shadow_lock, flags);

	return free;
}

static int _scsifront_put_rqid(struct vscsifrnt_info *info,