/*
 * sbp2.c - SBP-2 protocol driver for IEEE-1394
 *
 * Copyright (C) 2000 James Goodwin, Filanet Corporation (www.filanet.com)
 * jamesg@filanet.com (JSG)
 *
 * Copyright (C) 2003 Ben Collins <bcollins@debian.org>
 *
 * 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.
 */

/*
 * Brief Description:
 *
 * This driver implements the Serial Bus Protocol 2 (SBP-2) over IEEE-1394
 * under Linux. The SBP-2 driver is implemented as an IEEE-1394 high-level
 * driver. It also registers as a SCSI lower-level driver in order to accept
 * SCSI commands for transport using SBP-2.
 *
 * You may access any attached SBP-2 (usually storage devices) as regular
 * SCSI devices. E.g. mount /dev/sda1, fdisk, mkfs, etc..
 *
 * See http://www.t10.org/drafts.htm#sbp2 for the final draft of the SBP-2
 * specification and for where to purchase the official standard.
 *
 * TODO:
 *   - look into possible improvements of the SCSI error handlers
 *   - handle Unit_Characteristics.mgt_ORB_timeout and .ORB_size
 *   - handle Logical_Unit_Number.ordered
 *   - handle src == 1 in status blocks
 *   - reimplement the DMA mapping in absence of physical DMA so that
 *     bus_to_virt is no longer required
 *   - debug the handling of absent physical DMA
 *   - replace CONFIG_IEEE1394_SBP2_PHYS_DMA by automatic detection
 *     (this is easy but depends on the previous two TODO items)
 *   - make the parameter serialize_io configurable per device
 *   - move all requests to fetch agent registers into non-atomic context,
 *     replace all usages of sbp2util_node_write_no_wait by true transactions
 * Grep for inline FIXME comments below.
 */

#include <linux/compiler.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/dma-mapping.h>
#include <linux/gfp.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/stat.h>
#include <linux/string.h>
#include <linux/stringify.h>
#include <linux/types.h>
#include <linux/wait.h>
#include <linux/workqueue.h>

#include <asm/byteorder.h>
#include <asm/errno.h>
#include <asm/param.h>
#include <asm/scatterlist.h>
#include <asm/system.h>
#include <asm/types.h>

#ifdef CONFIG_IEEE1394_SBP2_PHYS_DMA
#include <asm/io.h> /* for bus_to_virt */
#endif

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

#include "csr1212.h"
#include "highlevel.h"
#include "hosts.h"
#include "ieee1394.h"
#include "ieee1394_core.h"
#include "ieee1394_hotplug.h"
#include "ieee1394_transactions.h"
#include "ieee1394_types.h"
#include "nodemgr.h"
#include "sbp2.h"

/*
 * Module load parameter definitions
 */

/*
 * Change max_speed on module load if you have a bad IEEE-1394
 * controller that has trouble running 2KB packets at 400mb.
 *
 * NOTE: On certain OHCI parts I have seen short packets on async transmit
 * (probably due to PCI latency/throughput issues with the part). You can
 * bump down the speed if you are running into problems.
 */
static int sbp2_max_speed = IEEE1394_SPEED_MAX;
module_param_named(max_speed, sbp2_max_speed, int, 0644);
MODULE_PARM_DESC(max_speed, "Force max speed "
		 "(3 = 800Mb/s, 2 = 400Mb/s, 1 = 200Mb/s, 0 = 100Mb/s)");

/*
 * Set serialize_io to 0 or N to use dynamically appended lists of command ORBs.
 * This is and always has been buggy in multiple subtle ways. See above TODOs.
 */
static int sbp2_serialize_io = 1;
module_param_named(serialize_io, sbp2_serialize_io, bool, 0444);
MODULE_PARM_DESC(serialize_io, "Serialize requests coming from SCSI drivers "
		 "(default = Y, faster but buggy = N)");

/*
 * Bump up max_sectors if you'd like to support very large sized
 * transfers. Please note that some older sbp2 bridge chips are broken for
 * transfers greater or equal to 128KB.  Default is a value of 255
 * sectors, or just under 128KB (at 512 byte sector size). I can note that
 * the Oxsemi sbp2 chipsets have no problems supporting very large
 * transfer sizes.
 */
static int sbp2_max_sectors = SBP2_MAX_SECTORS;
module_param_named(max_sectors, sbp2_max_sectors, int, 0444);
MODULE_PARM_DESC(max_sectors, "Change max sectors per I/O supported "
		 "(default = " __stringify(SBP2_MAX_SECTORS) ")");

/*
 * Exclusive login to sbp2 device? In most cases, the sbp2 driver should
 * do an exclusive login, as it's generally unsafe to have two hosts
 * talking to a single sbp2 device at the same time (filesystem coherency,
 * etc.). If you're running an sbp2 device that supports multiple logins,
 * and you're either running read-only filesystems or some sort of special
 * filesystem supporting multiple hosts, e.g. OpenGFS, Oracle Cluster
 * File System, or Lustre, then set exclusive_login to zero.
 *
 * So far only bridges from Oxford Semiconductor are known to support
 * concurrent logins. Depending on firmware, four or two concurrent logins
 * are possible on OXFW911 and newer Oxsemi bridges.
 */
static int sbp2_exclusive_login = 1;
module_param_named(exclusive_login, sbp2_exclusive_login, bool, 0644);
MODULE_PARM_DESC(exclusive_login, "Exclusive login to sbp2 device "
		 "(default = Y, use N for concurrent initiators)");

/*
 * If any of the following workarounds is required for your device to work,
 * please submit the kernel messages logged by sbp2 to the linux1394-devel
 * mailing list.
 *
 * - 128kB max transfer
 *   Limit transfer size. Necessary for some old bridges.
 *
 * - 36 byte inquiry
 *   When scsi_mod probes the device, let the inquiry command look like that
 *   from MS Windows.
 *
 * - skip mode page 8
 *   Suppress sending of mode_sense for mode page 8 if the device pretends to
 *   support the SCSI Primary Block commands instead of Reduced Block Commands.
 *
 * - fix capacity
 *   Tell sd_mod to correct the last sector number reported by read_capacity.
 *   Avoids access beyond actual disk limits on devices with an off-by-one bug.
 *   Don't use this with devices which don't have this bug.
 *
 * - override internal blacklist
 *   Instead of adding to the built-in blacklist, use only the workarounds
 *   specified in the module load parameter.
 *   Useful if a blacklist entry interfered with a non-broken device.
 */
static int sbp2_default_workarounds;
module_param_named(workarounds, sbp2_default_workarounds, int, 0644);
MODULE_PARM_DESC(workarounds, "Work around device bugs (default = 0"
	", 128kB max transfer = " __stringify(SBP2_WORKAROUND_128K_MAX_TRANS)
	", 36 byte inquiry = "    __stringify(SBP2_WORKAROUND_INQUIRY_36)
	", skip mode page 8 = "   __stringify(SBP2_WORKAROUND_MODE_SENSE_8)
	", fix capacity = "       __stringify(SBP2_WORKAROUND_FIX_CAPACITY)
	", override internal blacklist = " __stringify(SBP2_WORKAROUND_OVERRIDE)
	", or a combination)");

/*
 * This influences the format of the sysfs attribute
 * /sys/bus/scsi/devices/.../ieee1394_id.
 *
 * The default format is like in older kernels:  %016Lx:%d:%d
 * It contains the target's EUI-64, a number given to the logical unit by
 * the ieee1394 driver's nodemgr (starting at 0), and the LUN.
 *
 * The long format is:  %016Lx:%06x:%04x
 * It contains the target's EUI-64, the unit directory's directory_ID as per
 * IEEE 1212 clause 7.7.19, and the LUN.  This format comes closest to the
 * format of SBP(-3) target port and logical unit identifier as per SAM (SCSI
 * Architecture Model) rev.2 to 4 annex A.  Therefore and because it is
 * independent of the implementation of the ieee1394 nodemgr, the longer format
 * is recommended for future use.
 */
static int sbp2_long_sysfs_ieee1394_id;
module_param_named(long_ieee1394_id, sbp2_long_sysfs_ieee1394_id, bool, 0644);
MODULE_PARM_DESC(long_ieee1394_id, "8+3+2 bytes format of ieee1394_id in sysfs "
		 "(default = backwards-compatible = N, SAM-conforming = Y)");


#define SBP2_INFO(fmt, args...)	HPSB_INFO("sbp2: "fmt, ## args)
#define SBP2_ERR(fmt, args...)	HPSB_ERR("sbp2: "fmt, ## args)

/*
 * Globals
 */
static void sbp2scsi_complete_all_commands(struct sbp2_lu *, u32);
static void sbp2scsi_complete_command(struct sbp2_lu *, u32, struct scsi_cmnd *,
				      void (*)(struct scsi_cmnd *));
static struct sbp2_lu *sbp2_alloc_device(struct unit_directory *);
static int sbp2_start_device(struct sbp2_lu *);
static void sbp2_remove_device(struct sbp2_lu *);
static int sbp2_login_device(struct sbp2_lu *);
static int sbp2_reconnect_device(struct sbp2_lu *);
static int sbp2_logout_device(struct sbp2_lu *);
static void sbp2_host_reset(struct hpsb_host *);
static int sbp2_handle_status_write(struct hpsb_host *, int, int, quadlet_t *,
				    u64, size_t, u16);
static int sbp2_agent_reset(struct sbp2_lu *, int);
static void sbp2_parse_unit_directory(struct sbp2_lu *,
				      struct unit_directory *);
static int sbp2_set_busy_timeout(struct sbp2_lu *);
static int sbp2_max_speed_and_size(struct sbp2_lu *);


static const u8 sbp2_speedto_max_payload[] = { 0x7, 0x8, 0x9, 0xA, 0xB, 0xC };

static struct hpsb_highlevel sbp2_highlevel = {
	.name		= SBP2_DEVICE_NAME,
	.host_reset	= sbp2_host_reset,
};

static struct hpsb_address_ops sbp2_ops = {
	.write		= sbp2_handle_status_write
};

#ifdef CONFIG_IEEE1394_SBP2_PHYS_DMA
static int sbp2_handle_physdma_write(struct hpsb_host *, int, int, quadlet_t *,
				     u64, size_t, u16);
static int sbp2_handle_physdma_read(struct hpsb_host *, int, quadlet_t *, u64,
				    size_t, u16);

static struct hpsb_address_ops sbp2_physdma_ops = {
	.read		= sbp2_handle_physdma_read,
	.write		= sbp2_handle_physdma_write,
};
#endif


/*
 * Interface to driver core and IEEE 1394 core
 */
static struct ieee1394_device_id sbp2_id_table[] = {
	{
	 .match_flags	= IEEE1394_MATCH_SPECIFIER_ID | IEEE1394_MATCH_VERSION,
	 .specifier_id	= SBP2_UNIT_SPEC_ID_ENTRY & 0xffffff,
	 .version	= SBP2_SW_VERSION_ENTRY & 0xffffff},
	{}
};
MODULE_DEVICE_TABLE(ieee1394, sbp2_id_table);

static int sbp2_probe(struct device *);
static int sbp2_remove(struct device *);
static int sbp2_update(struct unit_directory *);

static struct hpsb_protocol_driver sbp2_driver = {
	.name		= SBP2_DEVICE_NAME,
	.id_table	= sbp2_id_table,
	.update		= sbp2_update,
	.driver		= {
		.probe		= sbp2_probe,
		.remove		= sbp2_remove,
	},
};


/*
 * Interface to SCSI core
 */
static int sbp2scsi_queuecommand(struct scsi_cmnd *,
				 void (*)(struct scsi_cmnd *));
static int sbp2scsi_abort(struct scsi_cmnd *);
static int sbp2scsi_reset(struct scsi_cmnd *);
static int sbp2scsi_slave_alloc(struct scsi_device *);
static int sbp2scsi_slave_configure(struct scsi_device *);
static void sbp2scsi_slave_destroy(struct scsi_device *);
static ssize_t sbp2_sysfs_ieee1394_id_show(struct device *,
					   struct device_attribute *, char *);

static DEVICE_ATTR(ieee1394_id, S_IRUGO, sbp2_sysfs_ieee1394_id_show, NULL);

static struct device_attribute *sbp2_sysfs_sdev_attrs[] = {
	&dev_attr_ieee1394_id,
	NULL
};

static struct scsi_host_template sbp2_shost_template = {
	.module			 = THIS_MODULE,
	.name			 = "SBP-2 IEEE-1394",
	.proc_name		 = SBP2_DEVICE_NAME,
	.queuecommand		 = sbp2scsi_queuecommand,
	.eh_abort_handler	 = sbp2scsi_abort,
	.eh_device_reset_handler = sbp2scsi_reset,
	.slave_alloc		 = sbp2scsi_slave_alloc,
	.slave_configure	 = sbp2scsi_slave_configure,
	.slave_destroy		 = sbp2scsi_slave_destroy,
	.this_id		 = -1,
	.sg_tablesize		 = SG_ALL,
	.use_clustering		 = ENABLE_CLUSTERING,
	.cmd_per_lun		 = SBP2_MAX_CMDS,
	.can_queue		 = SBP2_MAX_CMDS,
	.sdev_attrs		 = sbp2_sysfs_sdev_attrs,
};

/* for match-all entries in sbp2_workarounds_table */
#define SBP2_ROM_VALUE_WILDCARD 0x1000000

/*
 * List of devices with known bugs.
 *
 * The firmware_revision field, masked with 0xffff00, is the best indicator
 * for the type of bridge chip of a device.  It yields a few false positives
 * but this did not break correctly behaving devices so far.
 */
static const struct {
	u32 firmware_revision;
	u32 model_id;
	unsigned workarounds;
} sbp2_workarounds_table[] = {
	/* DViCO Momobay CX-1 with TSB42AA9 bridge */ {
		.firmware_revision	= 0x002800,
		.model_id		= 0x001010,
		.workarounds		= SBP2_WORKAROUND_INQUIRY_36 |
					  SBP2_WORKAROUND_MODE_SENSE_8,
	},
	/* Initio bridges, actually only needed for some older ones */ {
		.firmware_revision	= 0x000200,
		.model_id		= SBP2_ROM_VALUE_WILDCARD,
		.workarounds		= SBP2_WORKAROUND_INQUIRY_36,
	},
	/* Symbios bridge */ {
		.firmware_revision	= 0xa0b800,
		.model_id		= SBP2_ROM_VALUE_WILDCARD,
		.workarounds		= SBP2_WORKAROUND_128K_MAX_TRANS,
	},
	/* iPod 4th generation */ {
		.firmware_revision	= 0x0a2700,
		.model_id		= 0x000021,
		.workarounds		= SBP2_WORKAROUND_FIX_CAPACITY,
	},
	/* iPod mini */ {
		.firmware_revision	= 0x0a2700,
		.model_id		= 0x000023,
		.workarounds		= SBP2_WORKAROUND_FIX_CAPACITY,
	},
	/* iPod Photo */ {
		.firmware_revision	= 0x0a2700,
		.model_id		= 0x00007e,
		.workarounds		= SBP2_WORKAROUND_FIX_CAPACITY,
	}
};

/**************************************
 * General utility functions
 **************************************/

#ifndef __BIG_ENDIAN
/*
 * Converts a buffer from be32 to cpu byte ordering. Length is in bytes.
 */
static inline void sbp2util_be32_to_cpu_buffer(void *buffer, int length)
{
	u32 *temp = buffer;

	for (length = (length >> 2); length--; )
		temp[length] = be32_to_cpu(temp[length]);
}

/*
 * Converts a buffer from cpu to be32 byte ordering. Length is in bytes.
 */
static inline void sbp2util_cpu_to_be32_buffer(void *buffer, int length)
{
	u32 *temp = buffer;

	for (length = (length >> 2); length--; )
		temp[length] = cpu_to_be32(temp[length]);
}
#else /* BIG_ENDIAN */
/* Why waste the cpu cycles? */
#define sbp2util_be32_to_cpu_buffer(x,y) do {} while (0)
#define sbp2util_cpu_to_be32_buffer(x,y) do {} while (0)
#endif

static DECLARE_WAIT_QUEUE_HEAD(sbp2_access_wq);

/*
 * Waits for completion of an SBP-2 access request.