ide-scsi.c

讲述linux的初始化过程

/*
 * linux/drivers/scsi/ide-scsi.c	Version 0.9		Jul   4, 1999
 *
 * Copyright (C) 1996 - 1999 Gadi Oxman <[e-mail]>
 */

/*
 * Emulation of a SCSI host adapter for IDE ATAPI devices.
 *
 * With this driver, one can use the Linux SCSI drivers instead of the
 * native IDE ATAPI drivers.
 *
 * Ver 0.1   Dec  3 96   Initial version.
 * Ver 0.2   Jan 26 97   Fixed bug in cleanup_module() and added emulation
 *                        of MODE_SENSE_6/MODE_SELECT_6 for cdroms. Thanks
 *                        to Janos Farkas for pointing this out.
 *                       Avoid using bitfields in structures for m68k.
 *                       Added Scatter/Gather and DMA support.
 * Ver 0.4   Dec  7 97   Add support for ATAPI PD/CD drives.
 *                       Use variable timeout for each command.
 * Ver 0.5   Jan  2 98   Fix previous PD/CD support.
 *                       Allow disabling of SCSI-6 to SCSI-10 transformation.
 * Ver 0.6   Jan 27 98   Allow disabling of SCSI command translation layer
 *                        for access through /dev/sg.
 *                       Fix MODE_SENSE_6/MODE_SELECT_6/INQUIRY translation.
 * Ver 0.7   Dec 04 98   Ignore commands where lun != 0 to avoid multiple
 *                        detection of devices with CONFIG_SCSI_MULTI_LUN
 * Ver 0.8   Feb 05 99   Optical media need translation too. Reverse 0.7.
 * Ver 0.9   Jul 04 99   Fix a bug in SG_SET_TRANSFORM.
 */

#define IDESCSI_VERSION "0.9"

#include <linux/module.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/ioport.h>
#include <linux/blkdev.h>
#include <linux/errno.h>
#include <linux/hdreg.h>
#include <linux/malloc.h>
#include <linux/ide.h>

#include <asm/io.h>
#include <asm/bitops.h>
#include <asm/uaccess.h>

#include "scsi.h"
#include "hosts.h"
#include "sd.h"
#include "ide-scsi.h"
#include <scsi/sg.h>

#define IDESCSI_DEBUG_LOG		0

typedef struct idescsi_pc_s {
	u8 c[12];				/* Actual packet bytes */
	int request_transfer;			/* Bytes to transfer */
	int actually_transferred;		/* Bytes actually transferred */
	int buffer_size;			/* Size of our data buffer */
	struct request *rq;			/* The corresponding request */
	byte *buffer;				/* Data buffer */
	byte *current_position;			/* Pointer into the above buffer */
	struct scatterlist *sg;			/* Scatter gather table */
	int b_count;				/* Bytes transferred from current entry */
	Scsi_Cmnd *scsi_cmd;			/* SCSI command */
	void (*done)(Scsi_Cmnd *);		/* Scsi completion routine */
	unsigned long flags;			/* Status/Action flags */
	unsigned long timeout;			/* Command timeout */
} idescsi_pc_t;

/*
 *	Packet command status bits.
 */
#define PC_DMA_IN_PROGRESS		0	/* 1 while DMA in progress */
#define PC_WRITING			1	/* Data direction */
#define PC_TRANSFORM			2	/* transform SCSI commands */

/*
 *	SCSI command transformation layer
 */
#define IDESCSI_TRANSFORM		0	/* Enable/Disable transformation */
#define IDESCSI_SG_TRANSFORM		1	/* /dev/sg transformation */

/*
 *	Log flags
 */
#define IDESCSI_LOG_CMD			0	/* Log SCSI commands */

typedef struct {
	ide_drive_t *drive;
	idescsi_pc_t *pc;			/* Current packet command */
	unsigned long flags;			/* Status/Action flags */
	unsigned long transform;		/* SCSI cmd translation layer */
	unsigned long log;			/* log flags */
} idescsi_scsi_t;

/*
 *	Per ATAPI device status bits.
 */
#define IDESCSI_DRQ_INTERRUPT		0	/* DRQ interrupt device */

/*
 *	ide-scsi requests.
 */
#define IDESCSI_PC_RQ			90

/*
 *	Bits of the interrupt reason register.
 */
#define IDESCSI_IREASON_COD	0x1		/* Information transferred is command */
#define IDESCSI_IREASON_IO	0x2		/* The device requests us to read */

static void idescsi_discard_data (ide_drive_t *drive, unsigned int bcount)
{
	while (bcount--)
		IN_BYTE (IDE_DATA_REG);
}

static void idescsi_output_zeros (ide_drive_t *drive, unsigned int bcount)
{
	while (bcount--)
		OUT_BYTE (0, IDE_DATA_REG);
}

/*
 *	PIO data transfer routines using the scatter gather table.
 */
static void idescsi_input_buffers (ide_drive_t *drive, idescsi_pc_t *pc, unsigned int bcount)
{
	int count;

	while (bcount) {
		if (pc->sg - (struct scatterlist *) pc->scsi_cmd->request_buffer > pc->scsi_cmd->use_sg) {
			printk (KERN_ERR "ide-scsi: scatter gather table too small, discarding data\n");
			idescsi_discard_data (drive, bcount);
			return;
		}
		count = IDE_MIN (pc->sg->length - pc->b_count, bcount);
		atapi_input_bytes (drive, pc->sg->address + pc->b_count, count);
		bcount -= count; pc->b_count += count;
		if (pc->b_count == pc->sg->length) {
			pc->sg++;
			pc->b_count = 0;
		}
	}
}

static void idescsi_output_buffers (ide_drive_t *drive, idescsi_pc_t *pc, unsigned int bcount)
{
	int count;

	while (bcount) {
		if (pc->sg - (struct scatterlist *) pc->scsi_cmd->request_buffer > pc->scsi_cmd->use_sg) {
			printk (KERN_ERR "ide-scsi: scatter gather table too small, padding with zeros\n");
			idescsi_output_zeros (drive, bcount);
			return;
		}
		count = IDE_MIN (pc->sg->length - pc->b_count, bcount);
		atapi_output_bytes (drive, pc->sg->address + pc->b_count, count);
		bcount -= count; pc->b_count += count;
		if (pc->b_count == pc->sg->length) {
			pc->sg++;
			pc->b_count = 0;
		}
	}
}

/*
 *	Most of the SCSI commands are supported directly by ATAPI devices.
 *	idescsi_transform_pc handles the few exceptions.
 */
static inline void idescsi_transform_pc1 (ide_drive_t *drive, idescsi_pc_t *pc)
{
	u8 *c = pc->c, *scsi_buf = pc->buffer, *sc = pc->scsi_cmd->cmnd;
	char *atapi_buf;

	if (!test_bit(PC_TRANSFORM, &pc->flags))
		return;
	if (drive->media == ide_cdrom || drive->media == ide_optical) {
		if (c[0] == READ_6 || c[0] == WRITE_6) {
			c[8] = c[4];		c[5] = c[3];		c[4] = c[2];
			c[3] = c[1] & 0x1f;	c[2] = 0;		c[1] &= 0xe0;
			c[0] += (READ_10 - READ_6);
		}
		if (c[0] == MODE_SENSE || c[0] == MODE_SELECT) {
			if (!scsi_buf)
				return;
			if ((atapi_buf = kmalloc(pc->buffer_size + 4, GFP_ATOMIC)) == NULL)
				return;
			memset(atapi_buf, 0, pc->buffer_size + 4);
			memset (c, 0, 12);
			c[0] = sc[0] | 0x40;	c[1] = sc[1];		c[2] = sc[2];
			c[8] = sc[4] + 4;	c[9] = sc[5];
			if (sc[4] + 4 > 255)
				c[7] = sc[4] + 4 - 255;
			if (c[0] == MODE_SELECT_10) {
				atapi_buf[1] = scsi_buf[0];	/* Mode data length */
				atapi_buf[2] = scsi_buf[1];	/* Medium type */
				atapi_buf[3] = scsi_buf[2];	/* Device specific parameter */
				atapi_buf[7] = scsi_buf[3];	/* Block descriptor length */
				memcpy(atapi_buf + 8, scsi_buf + 4, pc->buffer_size - 4);
			}
			pc->buffer = atapi_buf;
			pc->request_transfer += 4;
			pc->buffer_size += 4;
		}
	}
}

static inline void idescsi_transform_pc2 (ide_drive_t *drive, idescsi_pc_t *pc)
{
	u8 *atapi_buf = pc->buffer;
	u8 *sc = pc->scsi_cmd->cmnd;
	u8 *scsi_buf = pc->scsi_cmd->request_buffer;

	if (!test_bit(PC_TRANSFORM, &pc->flags))
		return;
	if (drive->media == ide_cdrom || drive->media == ide_optical) {
		if (pc->c[0] == MODE_SENSE_10 && sc[0] == MODE_SENSE) {
			scsi_buf[0] = atapi_buf[1];		/* Mode data length */
			scsi_buf[1] = atapi_buf[2];		/* Medium type */
			scsi_buf[2] = atapi_buf[3];		/* Device specific parameter */
			scsi_buf[3] = atapi_buf[7];		/* Block descriptor length */
			memcpy(scsi_buf + 4, atapi_buf + 8, pc->request_transfer - 8);
		}
		if (pc->c[0] == INQUIRY) {
			scsi_buf[2] |= 2;			/* ansi_revision */
			scsi_buf[3] = (scsi_buf[3] & 0xf0) | 2;	/* response data format */
		}
	}
	if (atapi_buf && atapi_buf != scsi_buf)
		kfree(atapi_buf);
}

static inline void idescsi_free_bh (struct buffer_head *bh)
{
	struct buffer_head *bhp;

	while (bh) {
		bhp = bh;
		bh = bh->b_reqnext;
		kfree (bhp);
	}
}

static void hexdump(u8 *x, int len)
{
	int i;

	printk("[ ");
	for (i = 0; i < len; i++)
		printk("%x ", x[i]);
	printk("]\n");
}

static void idescsi_end_request (byte uptodate, ide_hwgroup_t *hwgroup)
{
	ide_drive_t *drive = hwgroup->drive;
	idescsi_scsi_t *scsi = drive->driver_data;
	struct request *rq = hwgroup->rq;
	idescsi_pc_t *pc = (idescsi_pc_t *) rq->buffer;
	int log = test_bit(IDESCSI_LOG_CMD, &scsi->log);
	u8 *scsi_buf;
	unsigned long flags;

	if (rq->cmd != IDESCSI_PC_RQ) {
		ide_end_request (uptodate, hwgroup);
		return;
	}
	ide_end_drive_cmd (drive, 0, 0);
	if (rq->errors >= ERROR_MAX) {
		pc->scsi_cmd->result = DID_ERROR << 16;
		if (log)
			printk ("ide-scsi: %s: I/O error for %lu\n", drive->name, pc->scsi_cmd->serial_number);
	} else if (rq->errors) {
		pc->scsi_cmd->result = (CHECK_CONDITION << 1) | (DID_OK << 16);
		if (log)
			printk ("ide-scsi: %s: check condition for %lu\n", drive->name, pc->scsi_cmd->serial_number);
	} else {
		pc->scsi_cmd->result = DID_OK << 16;
		idescsi_transform_pc2 (drive, pc);
		if (log) {
			printk ("ide-scsi: %s: suc %lu", drive->name, pc->scsi_cmd->serial_number);
			if (!test_bit(PC_WRITING, &pc->flags) && pc->actually_transferred && pc->actually_transferred <= 1024 && pc->buffer) {
				printk(", rst = ");
				scsi_buf = pc->scsi_cmd->request_buffer;
				hexdump(scsi_buf, IDE_MIN(16, pc->scsi_cmd->request_bufflen));
			} else printk("\n");
		}
	}
	spin_lock_irqsave(&io_request_lock,flags);	
	pc->done(pc->scsi_cmd);
	spin_unlock_irqrestore(&io_request_lock,flags);
	idescsi_free_bh (rq->bh);
	kfree(pc); kfree(rq);
	scsi->pc = NULL;
}

static inline unsigned long get_timeout(idescsi_pc_t *pc)
{
	return IDE_MAX(WAIT_CMD, pc->timeout - jiffies);
}

/*
 *	Our interrupt handler.
 */
static ide_startstop_t idescsi_pc_intr (ide_drive_t *drive)
{
	idescsi_scsi_t *scsi = drive->driver_data;
	byte status, ireason;
	int bcount;
	idescsi_pc_t *pc=scsi->pc;
	struct request *rq = pc->rq;
	unsigned int temp;

#if IDESCSI_DEBUG_LOG
	printk (KERN_INFO "ide-scsi: Reached idescsi_pc_intr interrupt handler\n");
#endif /* IDESCSI_DEBUG_LOG */

	if (test_and_clear_bit (PC_DMA_IN_PROGRESS, &pc->flags)) {
#if IDESCSI_DEBUG_LOG
		printk ("ide-scsi: %s: DMA complete\n", drive->name);
#endif /* IDESCSI_DEBUG_LOG */
		pc->actually_transferred=pc->request_transfer;
		(void) (HWIF(drive)->dmaproc(ide_dma_end, drive));
	}

	status = GET_STAT();						/* Clear the interrupt */

	if ((status & DRQ_STAT) == 0) {					/* No more interrupts */
		if (test_bit(IDESCSI_LOG_CMD, &scsi->log))
			printk (KERN_INFO "Packet command completed, %d bytes transferred\n", pc->actually_transferred);
		ide__sti();
		if (status & ERR_STAT)
			rq->errors++;
		idescsi_end_request (1, HWGROUP(drive));
		return ide_stopped;
	}
	bcount = IN_BYTE (IDE_BCOUNTH_REG) << 8 | IN_BYTE (IDE_BCOUNTL_REG);
	ireason = IN_BYTE (IDE_IREASON_REG);

	if (ireason & IDESCSI_IREASON_COD) {
		printk (KERN_ERR "ide-scsi: CoD != 0 in idescsi_pc_intr\n");
		return ide_do_reset (drive);
	}
	if (ireason & IDESCSI_IREASON_IO) {
		temp = pc->actually_transferred + bcount;
		if ( temp > pc->request_transfer) {
			if (temp > pc->buffer_size) {
				printk (KERN_ERR "ide-scsi: The scsi wants to send us more data than expected - discarding data\n");
				temp = pc->buffer_size - pc->actually_transferred;
				if (temp) {
					clear_bit(PC_WRITING, &pc->flags);
					if (pc->sg)
						idescsi_input_buffers(drive, pc, temp);
					else
						atapi_input_bytes(drive, pc->current_position, temp);
					printk(KERN_ERR "ide-scsi: transferred %d of %d bytes\n", temp, bcount);
				}
				pc->actually_transferred += temp;
				pc->current_position += temp;
				idescsi_discard_data (drive,bcount - temp);
				ide_set_handler(drive, &idescsi_pc_intr, get_timeout(pc), NULL);
				return ide_started;
			}
#if IDESCSI_DEBUG_LOG
			printk (KERN_NOTICE "ide-scsi: The scsi wants to send us more data than expected - allowing transfer\n");
#endif /* IDESCSI_DEBUG_LOG */
		}
	}
	if (ireason & IDESCSI_IREASON_IO) {
		clear_bit(PC_WRITING, &pc->flags);
		if (pc->sg)
			idescsi_input_buffers (drive, pc, bcount);
		else
			atapi_input_bytes (drive,pc->current_position,bcount);
	} else {
		set_bit(PC_WRITING, &pc->flags);
		if (pc->sg)
			idescsi_output_buffers (drive, pc, bcount);
		else
			atapi_output_bytes (drive,pc->current_position,bcount);
	}
	pc->actually_transferred+=bcount;				/* Update the current position */
	pc->current_position+=bcount;

	ide_set_handler(drive, &idescsi_pc_intr, get_timeout(pc), NULL);	/* And set the interrupt handler again */
	return ide_started;
}

static ide_startstop_t idescsi_transfer_pc (ide_drive_t *drive)
{
	idescsi_scsi_t *scsi = drive->driver_data;
	idescsi_pc_t *pc = scsi->pc;
	byte ireason;
	ide_startstop_t startstop;

	if (ide_wait_stat (&startstop,drive,DRQ_STAT,BUSY_STAT,WAIT_READY)) {
		printk (KERN_ERR "ide-scsi: Strange, packet command initiated yet DRQ isn't asserted\n");
		return startstop;
	}
	ireason = IN_BYTE (IDE_IREASON_REG);
	if ((ireason & (IDESCSI_IREASON_IO | IDESCSI_IREASON_COD)) != IDESCSI_IREASON_COD) {
		printk (KERN_ERR "ide-scsi: (IO,CoD) != (0,1) while issuing a packet command\n");
		return ide_do_reset (drive);
	}
	ide_set_handler(drive, &idescsi_pc_intr, get_timeout(pc), NULL);	/* Set the interrupt routine */
	atapi_output_bytes (drive, scsi->pc->c, 12);			/* Send the actual packet */
	return ide_started;
}

/*
 *	Issue a packet command
 */
static ide_startstop_t idescsi_issue_pc (ide_drive_t *drive, idescsi_pc_t *pc)
{
	idescsi_scsi_t *scsi = drive->driver_data;
	int bcount;
	struct request *rq = pc->rq;
	int dma_ok = 0;

	scsi->pc=pc;							/* Set the current packet command */
	pc->actually_transferred=0;					/* We haven't transferred any data yet */