ub.c

Linux块设备驱动源码

/*
 * The low performance USB storage driver (ub).
 *
 * Copyright (c) 1999, 2000 Matthew Dharm ([e-mail])
 * Copyright (C) 2004 Pete Zaitcev ([e-mail])
 *
 * This work is a part of Linux kernel, is derived from it,
 * and is not licensed separately. See file COPYING for details.
 *
 * TODO (sorted by decreasing priority)
 *  -- Kill first_open (Al Viro fixed the block layer now)
 *  -- Do resets with usb_device_reset (needs a thread context, use khubd)
 *  -- set readonly flag for CDs, set removable flag for CF readers
 *  -- do inquiry and verify we got a disk and not a tape (for LUN mismatch)
 *  -- special case some senses, e.g. 3a/0 -> no media present, reduce retries
 *  -- verify the 13 conditions and do bulk resets
 *  -- kill last_pipe and simply do two-state clearing on both pipes
 *  -- verify protocol (bulk) from USB descriptors (maybe...)
 *  -- highmem
 *  -- move top_sense and work_bcs into separate allocations (if they survive)
 *     for cache purists and esoteric architectures.
 *  -- Allocate structure for LUN 0 before the first ub_sync_tur, avoid NULL. ?
 *  -- prune comments, they are too volumnous
 *  -- Exterminate P3 printks
 *  -- Resove XXX's
 *  -- Redo "benh's retries", perhaps have spin-up code to handle them. V:D=?
 *  -- CLEAR, CLR2STS, CLRRS seem to be ripe for refactoring.
 */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/usb.h>
#include <linux/blkdev.h>
#include <linux/devfs_fs_kernel.h>
#include <linux/timer.h>
#include <scsi/scsi.h>

#define DRV_NAME "ub"
#define DEVFS_NAME DRV_NAME

#define UB_MAJOR 180

/*
 * The command state machine is the key model for understanding of this driver.
 *
 * The general rule is that all transitions are done towards the bottom
 * of the diagram, thus preventing any loops.
 *
 * An exception to that is how the STAT state is handled. A counter allows it
 * to be re-entered along the path marked with [C].
 *
 *       +--------+
 *       ! INIT   !
 *       +--------+
 *           !
 *        ub_scsi_cmd_start fails ->--------------------------------------\
 *           !                                                            !
 *           V                                                            !
 *       +--------+                                                       !
 *       ! CMD    !                                                       !
 *       +--------+                                                       !
 *           !                                            +--------+      !
 *         was -EPIPE -->-------------------------------->! CLEAR  !      !
 *           !                                            +--------+      !
 *           !                                                !           !
 *         was error -->------------------------------------- ! --------->\
 *           !                                                !           !
 *  /--<-- cmd->dir == NONE ?                                 !           !
 *  !        !                                                !           !
 *  !        V                                                !           !
 *  !    +--------+                                           !           !
 *  !    ! DATA   !                                           !           !
 *  !    +--------+                                           !           !
 *  !        !                           +---------+          !           !
 *  !      was -EPIPE -->--------------->! CLR2STS !          !           !
 *  !        !                           +---------+          !           !
 *  !        !                                !               !           !
 *  !        !                              was error -->---- ! --------->\
 *  !      was error -->--------------------- ! ------------- ! --------->\
 *  !        !                                !               !           !
 *  !        V                                !               !           !
 *  \--->+--------+                           !               !           !
 *       ! STAT   !<--------------------------/               !           !
 *  /--->+--------+                                           !           !
 *  !        !                                                !           !
 * [C]     was -EPIPE -->-----------\                         !           !
 *  !        !                      !                         !           !
 *  +<---- len == 0                 !                         !           !
 *  !        !                      !                         !           !
 *  !      was error -->--------------------------------------!---------->\
 *  !        !                      !                         !           !
 *  +<---- bad CSW                  !                         !           !
 *  +<---- bad tag                  !                         !           !
 *  !        !                      V                         !           !
 *  !        !                 +--------+                     !           !
 *  !        !                 ! CLRRS  !                     !           !
 *  !        !                 +--------+                     !           !
 *  !        !                      !                         !           !
 *  \------- ! --------------------[C]--------\               !           !
 *           !                                !               !           !
 *         cmd->error---\                +--------+           !           !
 *           !          +--------------->! SENSE  !<----------/           !
 *         STAT_FAIL----/                +--------+                       !
 *           !                                !                           V
 *           !                                V                      +--------+
 *           \--------------------------------\--------------------->! DONE   !
 *                                                                   +--------+
 */

/*
 * Definitions which have to be scattered once we understand the layout better.
 */

/* Transport (despite PR in the name) */
#define US_PR_BULK	0x50		/* bulk only */

/* Protocol */
#define US_SC_SCSI	0x06		/* Transparent */

/*
 * This many LUNs per USB device.
 * Every one of them takes a host, see UB_MAX_HOSTS.
 */
#define UB_MAX_LUNS   9

/*
 */

#define UB_MINORS_PER_MAJOR	8

#define UB_MAX_CDB_SIZE      16		/* Corresponds to Bulk */

#define UB_SENSE_SIZE  18

/*
 */

/* command block wrapper */
struct bulk_cb_wrap {
	__le32	Signature;		/* contains 'USBC' */
	u32	Tag;			/* unique per command id */
	__le32	DataTransferLength;	/* size of data */
	u8	Flags;			/* direction in bit 0 */
	u8	Lun;			/* LUN */
	u8	Length;			/* of of the CDB */
	u8	CDB[UB_MAX_CDB_SIZE];	/* max command */
};

#define US_BULK_CB_WRAP_LEN	31
#define US_BULK_CB_SIGN		0x43425355	/*spells out USBC */
#define US_BULK_FLAG_IN		1
#define US_BULK_FLAG_OUT	0

/* command status wrapper */
struct bulk_cs_wrap {
	__le32	Signature;		/* should = 'USBS' */
	u32	Tag;			/* same as original command */
	__le32	Residue;		/* amount not transferred */
	u8	Status;			/* see below */
};

#define US_BULK_CS_WRAP_LEN	13
#define US_BULK_CS_SIGN		0x53425355	/* spells out 'USBS' */
#define US_BULK_STAT_OK		0
#define US_BULK_STAT_FAIL	1
#define US_BULK_STAT_PHASE	2

/* bulk-only class specific requests */
#define US_BULK_RESET_REQUEST	0xff
#define US_BULK_GET_MAX_LUN	0xfe

/*
 */
struct ub_dev;

#define UB_MAX_REQ_SG	9	/* cdrecord requires 32KB and maybe a header */
#define UB_MAX_SECTORS 64

/*
 * A second is more than enough for a 32K transfer (UB_MAX_SECTORS)
 * even if a webcam hogs the bus, but some devices need time to spin up.
 */
#define UB_URB_TIMEOUT	(HZ*2)
#define UB_DATA_TIMEOUT	(HZ*5)	/* ZIP does spin-ups in the data phase */
#define UB_STAT_TIMEOUT	(HZ*5)	/* Same spinups and eject for a dataless cmd. */
#define UB_CTRL_TIMEOUT	(HZ/2)	/* 500ms ought to be enough to clear a stall */

/*
 * An instance of a SCSI command in transit.
 */
#define UB_DIR_NONE	0
#define UB_DIR_READ	1
#define UB_DIR_ILLEGAL2	2
#define UB_DIR_WRITE	3

#define UB_DIR_CHAR(c)  (((c)==UB_DIR_WRITE)? 'w': \
			 (((c)==UB_DIR_READ)? 'r': 'n'))

enum ub_scsi_cmd_state {
	UB_CMDST_INIT,			/* Initial state */
	UB_CMDST_CMD,			/* Command submitted */
	UB_CMDST_DATA,			/* Data phase */
	UB_CMDST_CLR2STS,		/* Clearing before requesting status */
	UB_CMDST_STAT,			/* Status phase */
	UB_CMDST_CLEAR,			/* Clearing a stall (halt, actually) */
	UB_CMDST_CLRRS,			/* Clearing before retrying status */
	UB_CMDST_SENSE,			/* Sending Request Sense */
	UB_CMDST_DONE			/* Final state */
};

static char *ub_scsi_cmd_stname[] = {
	".  ",
	"Cmd",
	"dat",
	"c2s",
	"sts",
	"clr",
	"crs",
	"Sen",
	"fin"
};

struct ub_scsi_cmd {
	unsigned char cdb[UB_MAX_CDB_SIZE];
	unsigned char cdb_len;

	unsigned char dir;		/* 0 - none, 1 - read, 3 - write. */
	unsigned char trace_index;
	enum ub_scsi_cmd_state state;
	unsigned int tag;
	struct ub_scsi_cmd *next;

	int error;			/* Return code - valid upon done */
	unsigned int act_len;		/* Return size */
	unsigned char key, asc, ascq;	/* May be valid if error==-EIO */

	int stat_count;			/* Retries getting status. */

	unsigned int len;		/* Requested length */
	unsigned int current_sg;
	unsigned int nsg;		/* sgv[nsg] */
	struct scatterlist sgv[UB_MAX_REQ_SG];

	struct ub_lun *lun;
	void (*done)(struct ub_dev *, struct ub_scsi_cmd *);
	void *back;
};

/*
 */
struct ub_capacity {
	unsigned long nsec;		/* Linux size - 512 byte sectors */
	unsigned int bsize;		/* Linux hardsect_size */
	unsigned int bshift;		/* Shift between 512 and hard sects */
};

/*
 * The SCSI command tracing structure.
 */

#define SCMD_ST_HIST_SZ   8
#define SCMD_TRACE_SZ    63		/* Less than 4KB of 61-byte lines */

struct ub_scsi_cmd_trace {
	int hcur;
	unsigned int tag;
	unsigned int req_size, act_size;
	unsigned char op;
	unsigned char dir;
	unsigned char key, asc, ascq;
	char st_hst[SCMD_ST_HIST_SZ];	
};

struct ub_scsi_trace {
	int cur;
	struct ub_scsi_cmd_trace vec[SCMD_TRACE_SZ];
};

/*
 * This is a direct take-off from linux/include/completion.h
 * The difference is that I do not wait on this thing, just poll.
 * When I want to wait (ub_probe), I just use the stock completion.
 *
 * Note that INIT_COMPLETION takes no lock. It is correct. But why
 * in the bloody hell that thing takes struct instead of pointer to struct
 * is quite beyond me. I just copied it from the stock completion.
 */
struct ub_completion {
	unsigned int done;
	spinlock_t lock;
};

static inline void ub_init_completion(struct ub_completion *x)
{
	x->done = 0;
	spin_lock_init(&x->lock);
}

#define UB_INIT_COMPLETION(x)	((x).done = 0)

static void ub_complete(struct ub_completion *x)
{
	unsigned long flags;

	spin_lock_irqsave(&x->lock, flags);
	x->done++;
	spin_unlock_irqrestore(&x->lock, flags);
}

static int ub_is_completed(struct ub_completion *x)
{
	unsigned long flags;
	int ret;

	spin_lock_irqsave(&x->lock, flags);
	ret = x->done;
	spin_unlock_irqrestore(&x->lock, flags);
	return ret;
}

/*
 */
struct ub_scsi_cmd_queue {
	int qlen, qmax;
	struct ub_scsi_cmd *head, *tail;
};

/*
 * The block device instance (one per LUN).
 */
struct ub_lun {
	struct ub_dev *udev;
	struct list_head link;
	struct gendisk *disk;
	int id;				/* Host index */
	int num;			/* LUN number */
	char name[16];

	int changed;			/* Media was changed */
	int removable;
	int readonly;
	int first_open;			/* Kludge. See ub_bd_open. */

	/* Use Ingo's mempool if or when we have more than one command. */
	/*
	 * Currently we never need more than one command for the whole device.
	 * However, giving every LUN a command is a cheap and automatic way
	 * to enforce fairness between them.
	 */
	int cmda[1];
	struct ub_scsi_cmd cmdv[1];

	struct ub_capacity capacity; 
};

/*
 * The USB device instance.
 */
struct ub_dev {
	spinlock_t lock;
	atomic_t poison;		/* The USB device is disconnected */
	int openc;			/* protected by ub_lock! */
					/* kref is too implicit for our taste */
	unsigned int tagcnt;
	char name[12];
	struct usb_device *dev;
	struct usb_interface *intf;

	struct list_head luns;

	unsigned int send_bulk_pipe;	/* cached pipe values */
	unsigned int recv_bulk_pipe;
	unsigned int send_ctrl_pipe;
	unsigned int recv_ctrl_pipe;

	struct tasklet_struct tasklet;

	struct ub_scsi_cmd_queue cmd_queue;
	struct ub_scsi_cmd top_rqs_cmd;	/* REQUEST SENSE */
	unsigned char top_sense[UB_SENSE_SIZE];

	struct ub_completion work_done;
	struct urb work_urb;
	struct timer_list work_timer;
	int last_pipe;			/* What might need clearing */
	__le32 signature;		/* Learned signature */
	struct bulk_cb_wrap work_bcb;
	struct bulk_cs_wrap work_bcs;
	struct usb_ctrlrequest work_cr;

	int sg_stat[6];
	struct ub_scsi_trace tr;
};

/*
 */
static void ub_cleanup(struct ub_dev *sc);
static int ub_request_fn_1(struct ub_lun *lun, struct request *rq);
static int ub_cmd_build_block(struct ub_dev *sc, struct ub_lun *lun,
    struct ub_scsi_cmd *cmd, struct request *rq);
static int ub_cmd_build_packet(struct ub_dev *sc, struct ub_lun *lun,
    struct ub_scsi_cmd *cmd, struct request *rq);
static void ub_rw_cmd_done(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
static void ub_end_rq(struct request *rq, int uptodate);
static int ub_submit_scsi(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
static void ub_urb_complete(struct urb *urb, struct pt_regs *pt);
static void ub_scsi_action(unsigned long _dev);
static void ub_scsi_dispatch(struct ub_dev *sc);
static void ub_scsi_urb_compl(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
static void ub_data_start(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
static void ub_state_done(struct ub_dev *sc, struct ub_scsi_cmd *cmd, int rc);
static int __ub_state_stat(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
static void ub_state_stat(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
static void ub_state_stat_counted(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
static void ub_state_sense(struct ub_dev *sc, struct ub_scsi_cmd *cmd);
static int ub_submit_clear_stall(struct ub_dev *sc, struct ub_scsi_cmd *cmd,
    int stalled_pipe);
static void ub_top_sense_done(struct ub_dev *sc, struct ub_scsi_cmd *scmd);
static int ub_sync_tur(struct ub_dev *sc, struct ub_lun *lun);
static int ub_sync_read_cap(struct ub_dev *sc, struct ub_lun *lun,
    struct ub_capacity *ret);
static int ub_probe_lun(struct ub_dev *sc, int lnum);

/*
 */
static struct usb_device_id ub_usb_ids[] = {
	// { USB_DEVICE_VER(0x0781, 0x0002, 0x0009, 0x0009) },	/* SDDR-31 */
	{ USB_INTERFACE_INFO(USB_CLASS_MASS_STORAGE, US_SC_SCSI, US_PR_BULK) },
	{ }
};

MODULE_DEVICE_TABLE(usb, ub_usb_ids);

/*
 * Find me a way to identify "next free minor" for add_disk(),
 * and the array disappears the next day. However, the number of
 * hosts has something to do with the naming and /proc/partitions.
 * This has to be thought out in detail before changing.
 * If UB_MAX_HOST was 1000, we'd use a bitmap. Or a better data structure.
 */
#define UB_MAX_HOSTS  26
static char ub_hostv[UB_MAX_HOSTS];

static DEFINE_SPINLOCK(ub_lock);	/* Locks globals and ->openc */

/*
 * The SCSI command tracing procedures.
 */

static void ub_cmdtr_new(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
{
	int n;
	struct ub_scsi_cmd_trace *t;

	if ((n = sc->tr.cur + 1) == SCMD_TRACE_SZ) n = 0;
	t = &sc->tr.vec[n];

	memset(t, 0, sizeof(struct ub_scsi_cmd_trace));
	t->tag = cmd->tag;
	t->op = cmd->cdb[0];
	t->dir = cmd->dir;
	t->req_size = cmd->len;
	t->st_hst[0] = cmd->state;

	sc->tr.cur = n;
	cmd->trace_index = n;
}

static void ub_cmdtr_state(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
{
	int n;
	struct ub_scsi_cmd_trace *t;

	t = &sc->tr.vec[cmd->trace_index];
	if (t->tag == cmd->tag) {
		if ((n = t->hcur + 1) == SCMD_ST_HIST_SZ) n = 0;
		t->st_hst[n] = cmd->state;
		t->hcur = n;
	}
}

static void ub_cmdtr_act_len(struct ub_dev *sc, struct ub_scsi_cmd *cmd)
{
	struct ub_scsi_cmd_trace *t;

	t = &sc->tr.vec[cmd->trace_index];
	if (t->tag == cmd->tag)
		t->act_size = cmd->act_len;
}

static void ub_cmdtr_sense(struct ub_dev *sc, struct ub_scsi_cmd *cmd,
    unsigned char *sense)
{
	struct ub_scsi_cmd_trace *t;

	t = &sc->tr.vec[cmd->trace_index];
	if (t->tag == cmd->tag) {
		t->key = sense[2] & 0x0F;
		t->asc = sense[12];
		t->ascq = sense[13];
	}
}