[PATCH] put ide i/o code from ide.c into ide-io.c and comment it

drivers/ide/ide-io.c

+/*
+ *	IDE I/O functions
+ *
+ *	Basic PIO and command management functionality.
+ *
+ * This code was split off from ide.c. See ide.c for history and original
+ * copyrights.
+ *
+ * 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, 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.
+ *
+ * For the avoidance of doubt the "preferred form" of this code is one which
+ * is in an open non patent encumbered format. Where cryptographic key signing
+ * forms part of the process of creating an executable the information
+ * including keys needed to generate an equivalently functional executable
+ * are deemed to be part of the source code.
+ */
+ 
+ 
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/string.h>
+#include <linux/kernel.h>
+#include <linux/timer.h>
+#include <linux/mm.h>
+#include <linux/interrupt.h>
+#include <linux/major.h>
+#include <linux/errno.h>
+#include <linux/genhd.h>
+#include <linux/blkpg.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/pci.h>
+#include <linux/delay.h>
+#include <linux/ide.h>
+#include <linux/devfs_fs_kernel.h>
+#include <linux/completion.h>
+#include <linux/reboot.h>
+#include <linux/cdrom.h>
+#include <linux/seq_file.h>
+#include <linux/device.h>
+#include <linux/kmod.h>
+
+#include <asm/byteorder.h>
+#include <asm/irq.h>
+#include <asm/uaccess.h>
+#include <asm/io.h>
+#include <asm/bitops.h>
+
+#include "ide_modes.h"
+
+#if (DISK_RECOVERY_TIME > 0)
+
+Error So the User Has To Fix the Compilation And Stop Hacking Port 0x43
+Does anyone ever use this anyway ??
+
+/*
+ * For really screwy hardware (hey, at least it *can* be used with Linux)
+ * we can enforce a minimum delay time between successive operations.
+ */
+static unsigned long read_timer (ide_hwif_t *hwif)
+{
+	unsigned long t, flags;
+	int i;
+	
+	/* FIXME this is completely unsafe! */
+	local_irq_save(flags);
+	t = jiffies * 11932;
+	outb_p(0, 0x43);
+	i = inb_p(0x40);
+	i |= inb_p(0x40) << 8;
+	local_irq_restore(flags);
+	return (t - i);
+}
+#endif /* DISK_RECOVERY_TIME */
+
+static inline void set_recovery_timer (ide_hwif_t *hwif)
+{
+#if (DISK_RECOVERY_TIME > 0)
+	hwif->last_time = read_timer(hwif);
+#endif /* DISK_RECOVERY_TIME */
+}
+
+/**
+ *	ide_end_request		-	complete an IDE I/O
+ *	@drive: IDE device for the I/O
+ *	@uptodate: 
+ *	@nr_sectors: number of sectors completed
+ *
+ *	This is our end_request wrapper function. We complete the I/O
+ *	update random number input and dequeue the request, which if
+ *	it was tagged may be out of order.
+ */
+ 
+int ide_end_request (ide_drive_t *drive, int uptodate, int nr_sectors)
+{
+	struct request *rq;
+	unsigned long flags;
+	int ret = 1;
+
+	spin_lock_irqsave(&ide_lock, flags);
+	rq = HWGROUP(drive)->rq;
+
+	BUG_ON(!(rq->flags & REQ_STARTED));
+
+	if (!nr_sectors)
+		nr_sectors = rq->hard_cur_sectors;
+
+	/*
+	 * decide whether to reenable DMA -- 3 is a random magic for now,
+	 * if we DMA timeout more than 3 times, just stay in PIO
+	 */
+	if (drive->state == DMA_PIO_RETRY && drive->retry_pio <= 3) {
+		drive->state = 0;
+		HWGROUP(drive)->hwif->ide_dma_on(drive);
+	}
+
+	if (!end_that_request_first(rq, uptodate, nr_sectors)) {
+		add_disk_randomness(rq->rq_disk);
+		if (!blk_rq_tagged(rq))
+			blkdev_dequeue_request(rq);
+		else
+			blk_queue_end_tag(&drive->queue, rq);
+		HWGROUP(drive)->rq = NULL;
+		end_that_request_last(rq);
+		ret = 0;
+	}
+	spin_unlock_irqrestore(&ide_lock, flags);
+	return ret;
+}
+
+EXPORT_SYMBOL(ide_end_request);
+
+/**
+ *	ide_end_drive_cmd	-	end an explicit drive command
+ *	@drive: command 
+ *	@stat: status bits
+ *	@err: error bits
+ *
+ *	Clean up after success/failure of an explicit drive command.
+ *	These get thrown onto the queue so they are synchronized with
+ *	real I/O operations on the drive.
+ *
+ *	In LBA48 mode we have to read the register set twice to get
+ *	all the extra information out.
+ */
+ 
+void ide_end_drive_cmd (ide_drive_t *drive, u8 stat, u8 err)
+{
+	ide_hwif_t *hwif = HWIF(drive);
+	unsigned long flags;
+	struct request *rq;
+
+	spin_lock_irqsave(&ide_lock, flags);
+	rq = HWGROUP(drive)->rq;
+	spin_unlock_irqrestore(&ide_lock, flags);
+
+	if (rq->flags & REQ_DRIVE_CMD) {
+		u8 *args = (u8 *) rq->buffer;
+		if (rq->errors == 0)
+			rq->errors = !OK_STAT(stat,READY_STAT,BAD_STAT);
+
+		if (args) {
+			args[0] = stat;
+			args[1] = err;
+			args[2] = hwif->INB(IDE_NSECTOR_REG);
+		}
+	} else if (rq->flags & REQ_DRIVE_TASK) {
+		u8 *args = (u8 *) rq->buffer;
+		if (rq->errors == 0)
+			rq->errors = !OK_STAT(stat,READY_STAT,BAD_STAT);
+
+		if (args) {
+			args[0] = stat;
+			args[1] = err;
+			args[2] = hwif->INB(IDE_NSECTOR_REG);
+			args[3] = hwif->INB(IDE_SECTOR_REG);
+			args[4] = hwif->INB(IDE_LCYL_REG);
+			args[5] = hwif->INB(IDE_HCYL_REG);
+			args[6] = hwif->INB(IDE_SELECT_REG);
+		}
+	} else if (rq->flags & REQ_DRIVE_TASKFILE) {
+		ide_task_t *args = (ide_task_t *) rq->special;
+		if (rq->errors == 0)
+			rq->errors = !OK_STAT(stat,READY_STAT,BAD_STAT);
+			
+		if (args) {
+			if (args->tf_in_flags.b.data) {
+				u16 data				= hwif->INW(IDE_DATA_REG);
+				args->tfRegister[IDE_DATA_OFFSET]	= (data) & 0xFF;
+				args->hobRegister[IDE_DATA_OFFSET_HOB]	= (data >> 8) & 0xFF;
+			}
+			args->tfRegister[IDE_ERROR_OFFSET]   = err;
+			args->tfRegister[IDE_NSECTOR_OFFSET] = hwif->INB(IDE_NSECTOR_REG);
+			args->tfRegister[IDE_SECTOR_OFFSET]  = hwif->INB(IDE_SECTOR_REG);
+			args->tfRegister[IDE_LCYL_OFFSET]    = hwif->INB(IDE_LCYL_REG);
+			args->tfRegister[IDE_HCYL_OFFSET]    = hwif->INB(IDE_HCYL_REG);
+			args->tfRegister[IDE_SELECT_OFFSET]  = hwif->INB(IDE_SELECT_REG);
+			args->tfRegister[IDE_STATUS_OFFSET]  = stat;
+
+			if (drive->addressing == 1) {
+				hwif->OUTB(drive->ctl|0x80, IDE_CONTROL_REG_HOB);
+				args->hobRegister[IDE_FEATURE_OFFSET_HOB] = hwif->INB(IDE_FEATURE_REG);
+				args->hobRegister[IDE_NSECTOR_OFFSET_HOB] = hwif->INB(IDE_NSECTOR_REG);
+				args->hobRegister[IDE_SECTOR_OFFSET_HOB]  = hwif->INB(IDE_SECTOR_REG);
+				args->hobRegister[IDE_LCYL_OFFSET_HOB]    = hwif->INB(IDE_LCYL_REG);
+				args->hobRegister[IDE_HCYL_OFFSET_HOB]    = hwif->INB(IDE_HCYL_REG);
+			}
+		}
+	}
+
+	spin_lock_irqsave(&ide_lock, flags);
+	blkdev_dequeue_request(rq);
+	HWGROUP(drive)->rq = NULL;
+	end_that_request_last(rq);
+	spin_unlock_irqrestore(&ide_lock, flags);
+}
+
+EXPORT_SYMBOL(ide_end_drive_cmd);
+
+/**
+ *	try_to_flush_leftover_data	-	flush junk
+ *	@drive: drive to flush
+ *
+ *	try_to_flush_leftover_data() is invoked in response to a drive
+ *	unexpectedly having its DRQ_STAT bit set.  As an alternative to
+ *	resetting the drive, this routine tries to clear the condition
+ *	by read a sector's worth of data from the drive.  Of course,
+ *	this may not help if the drive is *waiting* for data from *us*.
+ */
+void try_to_flush_leftover_data (ide_drive_t *drive)
+{
+	int i = (drive->mult_count ? drive->mult_count : 1) * SECTOR_WORDS;
+
+	if (drive->media != ide_disk)
+		return;
+	while (i > 0) {
+		u32 buffer[16];
+		u32 wcount = (i > 16) ? 16 : i;
+
+		i -= wcount;
+		HWIF(drive)->ata_input_data(drive, buffer, wcount);
+	}
+}
+
+EXPORT_SYMBOL(try_to_flush_leftover_data);
+
+/*
+ * FIXME Add an ATAPI error
+ */
+
+/**
+ *	ide_error	-	handle an error on the IDE
+ *	@drive: drive the error occurred on
+ *	@msg: message to report
+ *	@stat: status bits
+ *
+ *	ide_error() takes action based on the error returned by the drive.
+ *	For normal I/O that may well include retries. We deal with
+ *	both new-style (taskfile) and old style command handling here.
+ *	In the case of taskfile command handling there is work left to
+ *	do
+ */
+ 
+ide_startstop_t ide_error (ide_drive_t *drive, const char *msg, u8 stat)
+{
+	ide_hwif_t *hwif;
+	struct request *rq;
+	u8 err;
+
+	err = ide_dump_status(drive, msg, stat);
+	if (drive == NULL || (rq = HWGROUP(drive)->rq) == NULL)
+		return ide_stopped;
+
+	hwif = HWIF(drive);
+	/* retry only "normal" I/O: */
+	if (rq->flags & (REQ_DRIVE_CMD | REQ_DRIVE_TASK)) {
+		rq->errors = 1;
+		ide_end_drive_cmd(drive, stat, err);
+		return ide_stopped;
+	}
+	if (rq->flags & REQ_DRIVE_TASKFILE) {
+		rq->errors = 1;
+		ide_end_drive_cmd(drive, stat, err);
+//		ide_end_taskfile(drive, stat, err);
+		return ide_stopped;
+	}
+
+	if (stat & BUSY_STAT || ((stat & WRERR_STAT) && !drive->nowerr)) {
+		 /* other bits are useless when BUSY */
+		rq->errors |= ERROR_RESET;
+	} else {
+		if (drive->media != ide_disk)
+			goto media_out;
+
+		if (stat & ERR_STAT) {
+			/* err has different meaning on cdrom and tape */
+			if (err == ABRT_ERR) {
+				if (drive->select.b.lba &&
+				    (hwif->INB(IDE_COMMAND_REG) == WIN_SPECIFY))
+					/* some newer drives don't
+					 * support WIN_SPECIFY
+					 */
+					return ide_stopped;
+			} else if ((err & BAD_CRC) == BAD_CRC) {
+				drive->crc_count++;
+				/* UDMA crc error -- just retry the operation */
+			} else if (err & (BBD_ERR | ECC_ERR)) {
+				/* retries won't help these */
+				rq->errors = ERROR_MAX;
+			} else if (err & TRK0_ERR) {
+				/* help it find track zero */
+				rq->errors |= ERROR_RECAL;
+			}
+		}
+media_out:
+		if ((stat & DRQ_STAT) && rq_data_dir(rq) != WRITE)
+			try_to_flush_leftover_data(drive);
+	}
+	if (hwif->INB(IDE_STATUS_REG) & (BUSY_STAT|DRQ_STAT)) {
+		/* force an abort */
+		hwif->OUTB(WIN_IDLEIMMEDIATE,IDE_COMMAND_REG);
+	}
+	if (rq->errors >= ERROR_MAX) {
+		if (drive->driver != NULL)
+			DRIVER(drive)->end_request(drive, 0, 0);
+		else
+	 		ide_end_request(drive, 0, 0);
+	} else {
+		if ((rq->errors & ERROR_RESET) == ERROR_RESET) {
+			++rq->errors;
+			return ide_do_reset(drive);
+		}
+		if ((rq->errors & ERROR_RECAL) == ERROR_RECAL)
+			drive->special.b.recalibrate = 1;
+		++rq->errors;
+	}
+	return ide_stopped;
+}
+
+EXPORT_SYMBOL(ide_error);
+
+/**
+ *	ide_cmd		-	issue a simple drive command
+ *	@drive: drive the command is for
+ *	@cmd: command byte
+ *	@nsect: sector byte
+ *	@handler: handler for the command completion
+ *
+ *	Issue a simple drive command with interrupts.
+ *	The drive must be selected beforehand.
+ */
+ 
+void ide_cmd (ide_drive_t *drive, u8 cmd, u8 nsect, ide_handler_t *handler)
+{
+	ide_hwif_t *hwif = HWIF(drive);
+	if (HWGROUP(drive)->handler != NULL)
+		BUG();
+	ide_set_handler(drive, handler, WAIT_CMD, NULL);
+	if (IDE_CONTROL_REG)
+		hwif->OUTB(drive->ctl,IDE_CONTROL_REG);	/* clear nIEN */
+	SELECT_MASK(drive,0);
+	hwif->OUTB(nsect,IDE_NSECTOR_REG);
+	hwif->OUTB(cmd,IDE_COMMAND_REG);
+}
+
+EXPORT_SYMBOL(ide_cmd);
+
+/**
+ *	drive_cmd_intr		- 	drive command completion interrupt
+ *	@drive: drive the completion interrupt occurred on
+ *
+ *	drive_cmd_intr() is invoked on completion of a special DRIVE_CMD.
+ *	We do any neccessary daya reading and then wait for the drive to
+ *	go non busy. At that point we may read the error data and complete
+ *	the request
+ */
+ 
+ide_startstop_t drive_cmd_intr (ide_drive_t *drive)
+{
+	struct request *rq = HWGROUP(drive)->rq;
+	ide_hwif_t *hwif = HWIF(drive);
+	u8 *args = (u8 *) rq->buffer;
+	u8 stat = hwif->INB(IDE_STATUS_REG);
+	int retries = 10;
+
+	local_irq_enable();
+	if ((stat & DRQ_STAT) && args && args[3]) {
+		u8 io_32bit = drive->io_32bit;
+		drive->io_32bit = 0;
+		hwif->ata_input_data(drive, &args[4], args[3] * SECTOR_WORDS);
+		drive->io_32bit = io_32bit;
+		while (((stat = hwif->INB(IDE_STATUS_REG)) & BUSY_STAT) && retries--)
+			udelay(100);
+	}
+
+	if (!OK_STAT(stat, READY_STAT, BAD_STAT))
+		return DRIVER(drive)->error(drive, "drive_cmd", stat);
+		/* calls ide_end_drive_cmd */
+	ide_end_drive_cmd(drive, stat, hwif->INB(IDE_ERROR_REG));
+	return ide_stopped;
+}
+
+EXPORT_SYMBOL(drive_cmd_intr);
+
+/**
+ *	do_special		-	issue some special commands
+ *	@drive: drive the command is for
+ *
+ *	do_special() is used to issue WIN_SPECIFY, WIN_RESTORE, and WIN_SETMULT
+ *	commands to a drive.  It used to do much more, but has been scaled
+ *	back.
+ */
+
+ide_startstop_t do_special (ide_drive_t *drive)
+{
+	special_t *s = &drive->special;
+
+#ifdef DEBUG
+	printk("%s: do_special: 0x%02x\n", drive->name, s->all);
+#endif
+	if (s->b.set_tune) {
+		s->b.set_tune = 0;
+		if (HWIF(drive)->tuneproc != NULL)
+			HWIF(drive)->tuneproc(drive, drive->tune_req);
+	} else if (drive->driver != NULL) {
+		return DRIVER(drive)->special(drive);
+	} else if (s->all) {
+		printk(KERN_ERR "%s: bad special flag: 0x%02x\n", drive->name, s->all);
+		s->all = 0;
+	}
+	return ide_stopped;
+}
+
+EXPORT_SYMBOL(do_special);
+
+/**
+ *	execute_drive_command	-	issue special drive command
+ *	@drive: the drive to issue th command on
+ *	@rq: the request structure holding the command
+ *
+ *	execute_drive_cmd() issues a special drive command,  usually 
+ *	initiated by ioctl() from the external hdparm program. The
+ *	command can be a drive command, drive task or taskfile 
+ *	operation. Weirdly you can call it with NULL to wait for
+ *	all commands to finish. Don't do this as that is due to change
+ */
+
+ide_startstop_t execute_drive_cmd (ide_drive_t *drive, struct request *rq)
+{
+	ide_hwif_t *hwif = HWIF(drive);
+	if (rq->flags & REQ_DRIVE_TASKFILE) {
+ 		ide_task_t *args = rq->special;
+ 
+		if (!args)
+			goto done;
+ 
+		if (args->tf_out_flags.all != 0) 
+			return flagged_taskfile(drive, args);
+		return do_rw_taskfile(drive, args);
+	} else if (rq->flags & REQ_DRIVE_TASK) {
+		u8 *args = rq->buffer;
+		u8 sel;
+ 
+		if (!args)
+			goto done;
+#ifdef DEBUG
+ 		printk("%s: DRIVE_TASK_CMD ", drive->name);
+ 		printk("cmd=0x%02x ", args[0]);
+ 		printk("fr=0x%02x ", args[1]);
+ 		printk("ns=0x%02x ", args[2]);
+ 		printk("sc=0x%02x ", args[3]);
+ 		printk("lcyl=0x%02x ", args[4]);
+ 		printk("hcyl=0x%02x ", args[5]);
+ 		printk("sel=0x%02x\n", args[6]);
+#endif
+ 		hwif->OUTB(args[1], IDE_FEATURE_REG);
+ 		hwif->OUTB(args[3], IDE_SECTOR_REG);
+ 		hwif->OUTB(args[4], IDE_LCYL_REG);
+ 		hwif->OUTB(args[5], IDE_HCYL_REG);
+ 		sel = (args[6] & ~0x10);
+ 		if (drive->select.b.unit)
+ 			sel |= 0x10;
+ 		hwif->OUTB(sel, IDE_SELECT_REG);
+ 		ide_cmd(drive, args[0], args[2], &drive_cmd_intr);
+ 		return ide_started;
+ 	} else if (rq->flags & REQ_DRIVE_CMD) {
+ 		u8 *args = rq->buffer;
+
+		if (!args)
+			goto done;
+#ifdef DEBUG
+ 		printk("%s: DRIVE_CMD ", drive->name);
+ 		printk("cmd=0x%02x ", args[0]);
+ 		printk("sc=0x%02x ", args[1]);
+ 		printk("fr=0x%02x ", args[2]);
+ 		printk("xx=0x%02x\n", args[3]);
+#endif
+ 		if (args[0] == WIN_SMART) {
+ 			hwif->OUTB(0x4f, IDE_LCYL_REG);
+ 			hwif->OUTB(0xc2, IDE_HCYL_REG);
+ 			hwif->OUTB(args[2],IDE_FEATURE_REG);
+ 			hwif->OUTB(args[1],IDE_SECTOR_REG);
+ 			ide_cmd(drive, args[0], args[3], &drive_cmd_intr);
+ 			return ide_started;
+ 		}
+ 		hwif->OUTB(args[2],IDE_FEATURE_REG);
+ 		ide_cmd(drive, args[0], args[1], &drive_cmd_intr);
+ 		return ide_started;
+ 	}
+
+done:
+ 	/*
+ 	 * NULL is actually a valid way of waiting for
+ 	 * all current requests to be flushed from the queue.
+ 	 */
+#ifdef DEBUG
+ 	printk("%s: DRIVE_CMD (null)\n", drive->name);
+#endif
+ 	ide_end_drive_cmd(drive,
+			hwif->INB(IDE_STATUS_REG),
+			hwif->INB(IDE_ERROR_REG));
+ 	return ide_stopped;
+}
+
+EXPORT_SYMBOL(execute_drive_cmd);
+
+/**
+ *	start_request	-	start of I/O and command issuing for IDE
+ *
+ *	start_request() initiates handling of a new I/O request. It
+ *	accepts commands and I/O (read/write) requests. It also does
+ *	the final remapping for weird stuff like EZDrive. Once 
+ *	device mapper can work sector level the EZDrive stuff can go away
+ *
+ *	FIXME: this function needs a rename
+ */
+ 
+ide_startstop_t start_request (ide_drive_t *drive, struct request *rq)
+{
+	ide_startstop_t startstop;
+	unsigned long block;
+
+	BUG_ON(!(rq->flags & REQ_STARTED));
+
+#ifdef DEBUG
+	printk("%s: start_request: current=0x%08lx\n",
+		HWIF(drive)->name, (unsigned long) rq);
+#endif
+
+	/* bail early if we've exceeded max_failures */
+	if (drive->max_failures && (drive->failures > drive->max_failures)) {
+		goto kill_rq;
+	}
+
+	/*
+	 * bail early if we've sent a device to sleep, however how to wake
+	 * this needs to be a masked flag.  FIXME for proper operations.
+	 */
+	if (drive->suspend_reset)
+		goto kill_rq;
+
+	block    = rq->sector;
+	if (blk_fs_request(rq) &&
+	    (drive->media == ide_disk || drive->media == ide_floppy)) {
+		block += drive->sect0;
+	}
+	/* Yecch - this will shift the entire interval,
+	   possibly killing some innocent following sector */
+	if (block == 0 && drive->remap_0_to_1 == 1)
+		block = 1;  /* redirect MBR access to EZ-Drive partn table */
+
+#if (DISK_RECOVERY_TIME > 0)
+	while ((read_timer() - HWIF(drive)->last_time) < DISK_RECOVERY_TIME);
+#endif
+
+	SELECT_DRIVE(drive);
+	if (ide_wait_stat(&startstop, drive, drive->ready_stat, BUSY_STAT|DRQ_STAT, WAIT_READY)) {
+		printk(KERN_ERR "%s: drive not ready for command\n", drive->name);
+		return startstop;
+	}
+	if (!drive->special.all) {
+		if (rq->flags & (REQ_DRIVE_CMD | REQ_DRIVE_TASK))
+			return execute_drive_cmd(drive, rq);
+		else if (rq->flags & REQ_DRIVE_TASKFILE)
+			return execute_drive_cmd(drive, rq);
+
+		if (drive->driver != NULL) {
+			return (DRIVER(drive)->do_request(drive, rq, block));
+		}
+		printk(KERN_ERR "%s: media type %d not supported\n", drive->name, drive->media);
+		goto kill_rq;
+	}
+	return do_special(drive);
+kill_rq:
+	if (drive->driver != NULL)
+		DRIVER(drive)->end_request(drive, 0, 0);
+	else
+		ide_end_request(drive, 0, 0);
+	return ide_stopped;
+}
+
+EXPORT_SYMBOL(start_request);
+
+/**
+ *	restart_request		-	reissue an IDE request
+ *	@drive: drive for request
+ *	@rq: request to reissue
+ *
+ *	Reissue a request. See start_request for details and for
+ *	FIXME
+ */
+ 
+int restart_request (ide_drive_t *drive, struct request *rq)
+{
+	(void) start_request(drive, rq);
+	return 0;
+}
+
+EXPORT_SYMBOL(restart_request);
+
+/**
+ *	ide_stall_queue		-	pause an IDE device
+ *	@drive: drive to stall
+ *	@timeout: time to stall for (jiffies)
+ *
+ *	ide_stall_queue() can be used by a drive to give excess bandwidth back
+ *	to the hwgroup by sleeping for timeout jiffies.
+ */
+ 
+void ide_stall_queue (ide_drive_t *drive, unsigned long timeout)
+{
+	if (timeout > WAIT_WORSTCASE)
+		timeout = WAIT_WORSTCASE;
+	drive->sleep = timeout + jiffies;
+}
+
+EXPORT_SYMBOL(ide_stall_queue);
+
+#define WAKEUP(drive)	((drive)->service_start + 2 * (drive)->service_time)
+
+/**
+ *	choose_drive		-	select a drive to service
+ *	@hwgroup: hardware group to select on
+ *
+ *	choose_drive() selects the next drive which will be serviced.
+ *	This is neccessary because the IDE layer can't issue commands
+ *	to both drives on the same cable, unlike SCSI.
+ */
+ 
+static inline ide_drive_t *choose_drive (ide_hwgroup_t *hwgroup)
+{
+	ide_drive_t *drive, *best;
+
+repeat:	
+	best = NULL;
+	drive = hwgroup->drive;
+	do {
+		if (!blk_queue_empty(&drive->queue) && (!drive->sleep || time_after_eq(jiffies, drive->sleep))) {
+			if (!best
+			 || (drive->sleep && (!best->sleep || 0 < (signed long)(best->sleep - drive->sleep)))
+			 || (!best->sleep && 0 < (signed long)(WAKEUP(best) - WAKEUP(drive))))
+			{
+				if (!blk_queue_plugged(&drive->queue))
+					best = drive;
+			}
+		}
+	} while ((drive = drive->next) != hwgroup->drive);
+	if (best && best->nice1 && !best->sleep && best != hwgroup->drive && best->service_time > WAIT_MIN_SLEEP) {
+		long t = (signed long)(WAKEUP(best) - jiffies);
+		if (t >= WAIT_MIN_SLEEP) {
+		/*
+		 * We *may* have some time to spare, but first let's see if
+		 * someone can potentially benefit from our nice mood today..
+		 */
+			drive = best->next;
+			do {
+				if (!drive->sleep
+				/* FIXME: use time_before */
+				 && 0 < (signed long)(WAKEUP(drive) - (jiffies - best->service_time))
+				 && 0 < (signed long)((jiffies + t) - WAKEUP(drive)))
+				{
+					ide_stall_queue(best, IDE_MIN(t, 10 * WAIT_MIN_SLEEP));
+					goto repeat;
+				}
+			} while ((drive = drive->next) != best);
+		}
+	}
+	return best;
+}
+
+/*
+ * Issue a new request to a drive from hwgroup
+ * Caller must have already done spin_lock_irqsave(&ide_lock, ..);
+ *
+ * A hwgroup is a serialized group of IDE interfaces.  Usually there is
+ * exactly one hwif (interface) per hwgroup, but buggy controllers (eg. CMD640)
+ * may have both interfaces in a single hwgroup to "serialize" access.
+ * Or possibly multiple ISA interfaces can share a common IRQ by being grouped
+ * together into one hwgroup for serialized access.
+ *
+ * Note also that several hwgroups can end up sharing a single IRQ,
+ * possibly along with many other devices.  This is especially common in
+ * PCI-based systems with off-board IDE controller cards.
+ *
+ * The IDE driver uses the single global ide_lock spinlock to protect
+ * access to the request queues, and to protect the hwgroup->busy flag.
+ *
+ * The first thread into the driver for a particular hwgroup sets the
+ * hwgroup->busy flag to indicate that this hwgroup is now active,
+ * and then initiates processing of the top request from the request queue.
+ *
+ * Other threads attempting entry notice the busy setting, and will simply
+ * queue their new requests and exit immediately.  Note that hwgroup->busy
+ * remains set even when the driver is merely awaiting the next interrupt.
+ * Thus, the meaning is "this hwgroup is busy processing a request".
+ *
+ * When processing of a request completes, the completing thread or IRQ-handler
+ * will start the next request from the queue.  If no more work remains,
+ * the driver will clear the hwgroup->busy flag and exit.
+ *
+ * The ide_lock (spinlock) is used to protect all access to the
+ * hwgroup->busy flag, but is otherwise not needed for most processing in
+ * the driver.  This makes the driver much more friendlier to shared IRQs
+ * than previous designs, while remaining 100% (?) SMP safe and capable.
+ */
+/* --BenH: made non-static as ide-pmac.c uses it to kick the hwgroup back
+ *         into life on wakeup from machine sleep.
+ */ 
+void ide_do_request (ide_hwgroup_t *hwgroup, int masked_irq)
+{
+	ide_drive_t	*drive;
+	ide_hwif_t	*hwif;
+	struct request	*rq;
+	ide_startstop_t	startstop;
+
+	/* for atari only: POSSIBLY BROKEN HERE(?) */
+	ide_get_lock(&ide_intr_lock, ide_intr, hwgroup);
+
+	/* necessary paranoia: ensure IRQs are masked on local CPU */
+	local_irq_disable();
+
+	while (!hwgroup->busy) {
+		hwgroup->busy = 1;
+		drive = choose_drive(hwgroup);
+		if (drive == NULL) {
+			unsigned long sleep = 0;
+			hwgroup->rq = NULL;
+			drive = hwgroup->drive;
+			do {
+				if (drive->sleep && (!sleep || 0 < (signed long)(sleep - drive->sleep)))
+					sleep = drive->sleep;
+			} while ((drive = drive->next) != hwgroup->drive);
+			if (sleep) {
+		/*
+		 * Take a short snooze, and then wake up this hwgroup again.
+		 * This gives other hwgroups on the same a chance to
+		 * play fairly with us, just in case there are big differences
+		 * in relative throughputs.. don't want to hog the cpu too much.
+		 */
+				if (time_before(sleep, jiffies + WAIT_MIN_SLEEP))
+					sleep = jiffies + WAIT_MIN_SLEEP;
+#if 1
+				if (timer_pending(&hwgroup->timer))
+					printk(KERN_CRIT "ide_set_handler: timer already active\n");
+#endif
+				/* so that ide_timer_expiry knows what to do */
+				hwgroup->sleeping = 1;
+				mod_timer(&hwgroup->timer, sleep);
+				/* we purposely leave hwgroup->busy==1
+				 * while sleeping */
+			} else {
+				/* Ugly, but how can we sleep for the lock
+				 * otherwise? perhaps from tq_disk?
+				 */
+
+				/* for atari only */
+				ide_release_lock(&ide_intr_lock);
+				hwgroup->busy = 0;
+			}
+
+			/* no more work for this hwgroup (for now) */
+			return;
+		}
+		hwif = HWIF(drive);
+		if (hwgroup->hwif->sharing_irq &&
+		    hwif != hwgroup->hwif &&
+		    hwif->io_ports[IDE_CONTROL_OFFSET]) {
+			/* set nIEN for previous hwif */
+			SELECT_INTERRUPT(drive);
+		}
+		hwgroup->hwif = hwif;
+		hwgroup->drive = drive;
+		drive->sleep = 0;
+		drive->service_start = jiffies;
+
+queue_next:
+		if (!ata_can_queue(drive)) {
+			if (!ata_pending_commands(drive))
+				hwgroup->busy = 0;
+
+			break;
+		}
+
+		if (blk_queue_plugged(&drive->queue)) {
+			if (drive->using_tcq)
+				break;
+
+			printk(KERN_ERR "ide: huh? queue was plugged!\n");
+			break;
+		}
+
+		/*
+		 * we know that the queue isn't empty, but this can happen
+		 * if the q->prep_rq_fn() decides to kill a request
+		 */
+		rq = elv_next_request(&drive->queue);
+		if (!rq) {
+			hwgroup->busy = !!ata_pending_commands(drive);
+			break;
+		}
+
+		if (!rq->bio && ata_pending_commands(drive))
+			break;
+
+		hwgroup->rq = rq;
+
+		/*
+		 * Some systems have trouble with IDE IRQs arriving while
+		 * the driver is still setting things up.  So, here we disable
+		 * the IRQ used by this interface while the request is being started.
+		 * This may look bad at first, but pretty much the same thing
+		 * happens anyway when any interrupt comes in, IDE or otherwise
+		 *  -- the kernel masks the IRQ while it is being handled.
+		 */
+		if (masked_irq && hwif->irq != masked_irq)
+			disable_irq_nosync(hwif->irq);
+		spin_unlock(&ide_lock);
+		local_irq_enable();
+			/* allow other IRQs while we start this request */
+		startstop = start_request(drive, rq);
+		spin_lock_irq(&ide_lock);
+		if (masked_irq && hwif->irq != masked_irq)
+			enable_irq(hwif->irq);
+		if (startstop == ide_released)
+			goto queue_next;
+		if (startstop == ide_stopped)
+			hwgroup->busy = 0;
+	}
+}
+
+EXPORT_SYMBOL(ide_do_request);
+
+/*
+ * Passes the stuff to ide_do_request
+ */
+void do_ide_request(request_queue_t *q)
+{
+	ide_do_request(q->queuedata, 0);
+}
+
+/*
+ * un-busy the hwgroup etc, and clear any pending DMA status. we want to
+ * retry the current request in pio mode instead of risking tossing it
+ * all away
+ */
+void ide_dma_timeout_retry(ide_drive_t *drive)
+{
+	ide_hwif_t *hwif = HWIF(drive);
+	struct request *rq;
+
+	/*
+	 * end current dma transaction
+	 */
+	(void) hwif->ide_dma_end(drive);
+
+	/*
+	 * complain a little, later we might remove some of this verbosity
+	 */
+	printk(KERN_WARNING "%s: timeout waiting for DMA\n", drive->name);
+	(void) hwif->ide_dma_timeout(drive);
+
+	/*
+	 * disable dma for now, but remember that we did so because of
+	 * a timeout -- we'll reenable after we finish this next request
+	 * (or rather the first chunk of it) in pio.
+	 */
+	drive->retry_pio++;
+	drive->state = DMA_PIO_RETRY;
+	(void) hwif->ide_dma_off_quietly(drive);
+
+	/*
+	 * un-busy drive etc (hwgroup->busy is cleared on return) and
+	 * make sure request is sane
+	 */
+	rq = HWGROUP(drive)->rq;
+	HWGROUP(drive)->rq = NULL;
+
+	rq->errors = 0;
+	rq->sector = rq->bio->bi_sector;
+	rq->current_nr_sectors = bio_iovec(rq->bio)->bv_len >> 9;
+	rq->hard_cur_sectors = rq->current_nr_sectors;
+	if (rq->bio)
+		rq->buffer = NULL;
+}
+
+EXPORT_SYMBOL(ide_dma_timeout_retry);
+
+/**
+ *	ide_timer_expiry	-	handle lack of an IDE interrupt
+ *	@data: timer callback magic (hwgroup)
+ *
+ *	An IDE command has timed out before the expected drive return
+ *	occurred. At this point we attempt to clean up the current
+ *	mess. If the current handler includes an expiry handler then
+ *	we invoke the expiry handler, and providing it is happy the
+ *	work is done. If that fails we apply generic recovery rules
+ *	invoking the handler and checking the drive DMA status. We
+ *	have an excessively incestuous relationship with the DMA
+ *	logic that wants cleaning up.
+ */
+ 
+void ide_timer_expiry (unsigned long data)
+{
+	ide_hwgroup_t	*hwgroup = (ide_hwgroup_t *) data;
+	ide_handler_t	*handler;
+	ide_expiry_t	*expiry;
+ 	unsigned long	flags;
+	unsigned long	wait;
+
+	spin_lock_irqsave(&ide_lock, flags);
+	del_timer(&hwgroup->timer);
+
+	if ((handler = hwgroup->handler) == NULL) {
+		/*
+		 * Either a marginal timeout occurred
+		 * (got the interrupt just as timer expired),
+		 * or we were "sleeping" to give other devices a chance.
+		 * Either way, we don't really want to complain about anything.
+		 */
+		if (hwgroup->sleeping) {
+			hwgroup->sleeping = 0;
+			hwgroup->busy = 0;
+		}
+	} else {
+		ide_drive_t *drive = hwgroup->drive;
+		if (!drive) {
+			printk(KERN_ERR "ide_timer_expiry: hwgroup->drive was NULL\n");
+			hwgroup->handler = NULL;
+		} else {
+			ide_hwif_t *hwif;
+			ide_startstop_t startstop = ide_stopped;
+			if (!hwgroup->busy) {
+				hwgroup->busy = 1;	/* paranoia */
+				printk(KERN_ERR "%s: ide_timer_expiry: hwgroup->busy was 0 ??\n", drive->name);
+			}
+			if ((expiry = hwgroup->expiry) != NULL) {
+				/* continue */
+				if ((wait = expiry(drive)) != 0) {
+					/* reset timer */
+					hwgroup->timer.expires  = jiffies + wait;
+					add_timer(&hwgroup->timer);
+					spin_unlock_irqrestore(&ide_lock, flags);
+					return;
+				}
+			}
+			hwgroup->handler = NULL;
+			/*
+			 * We need to simulate a real interrupt when invoking
+			 * the handler() function, which means we need to
+			 * globally mask the specific IRQ:
+			 */
+			spin_unlock(&ide_lock);
+			hwif  = HWIF(drive);
+#if DISABLE_IRQ_NOSYNC
+			disable_irq_nosync(hwif->irq);
+#else
+			/* disable_irq_nosync ?? */
+			disable_irq(hwif->irq);
+#endif /* DISABLE_IRQ_NOSYNC */
+			/* local CPU only,
+			 * as if we were handling an interrupt */
+			local_irq_disable();
+			if (hwgroup->poll_timeout != 0) {
+				startstop = handler(drive);
+			} else if (drive_is_ready(drive)) {
+				if (drive->waiting_for_dma)
+					(void) hwgroup->hwif->ide_dma_lostirq(drive);
+				(void)ide_ack_intr(hwif);
+				printk(KERN_WARNING "%s: lost interrupt\n", drive->name);
+				startstop = handler(drive);
+			} else {
+				if (drive->waiting_for_dma) {
+					startstop = ide_stopped;
+					ide_dma_timeout_retry(drive);
+				} else
+					startstop = DRIVER(drive)->error(drive, "irq timeout", hwif->INB(IDE_STATUS_REG));
+			}
+			set_recovery_timer(hwif);
+			drive->service_time = jiffies - drive->service_start;
+			enable_irq(hwif->irq);
+			spin_lock_irq(&ide_lock);
+			if (startstop == ide_stopped)
+				hwgroup->busy = 0;
+		}
+	}
+	ide_do_request(hwgroup, 0);
+	spin_unlock_irqrestore(&ide_lock, flags);
+}
+
+EXPORT_SYMBOL(ide_timer_expiry);
+
+/**
+ *	unexpected_intr		-	handle an unexpected IDE interrupt
+ *	@irq: interrupt line
+ *	@hwgroup: hwgroup being processed
+ *
+ *	There's nothing really useful we can do with an unexpected interrupt,
+ *	other than reading the status register (to clear it), and logging it.
+ *	There should be no way that an irq can happen before we're ready for it,
+ *	so we needn't worry much about losing an "important" interrupt here.
+ *
+ *	On laptops (and "green" PCs), an unexpected interrupt occurs whenever
+ *	the drive enters "idle", "standby", or "sleep" mode, so if the status
+ *	looks "good", we just ignore the interrupt completely.
+ *
+ *	This routine assumes __cli() is in effect when called.
+ *
+ *	If an unexpected interrupt happens on irq15 while we are handling irq14
+ *	and if the two interfaces are "serialized" (CMD640), then it looks like
+ *	we could screw up by interfering with a new request being set up for 
+ *	irq15.
+ *
+ *	In reality, this is a non-issue.  The new command is not sent unless 
+ *	the drive is ready to accept one, in which case we know the drive is
+ *	not trying to interrupt us.  And ide_set_handler() is always invoked
+ *	before completing the issuance of any new drive command, so we will not
+ *	be accidentally invoked as a result of any valid command completion
+ *	interrupt.
+ *
+ *	Note that we must walk the entire hwgroup here. We know which hwif
+ *	is doing the current command, but we don't know which hwif burped
+ *	mysteriously.
+ */
+ 
+static void unexpected_intr (int irq, ide_hwgroup_t *hwgroup)
+{
+	u8 stat;
+	ide_hwif_t *hwif = hwgroup->hwif;
+
+	/*
+	 * handle the unexpected interrupt
+	 */
+	do {
+		if (hwif->irq == irq) {
+			stat = hwif->INB(hwif->io_ports[IDE_STATUS_OFFSET]);
+			if (!OK_STAT(stat, READY_STAT, BAD_STAT)) {
+				/* Try to not flood the console with msgs */
+				static unsigned long last_msgtime, count;
+				++count;
+				if (time_after(jiffies, last_msgtime + HZ)) {
+					last_msgtime = jiffies;
+					printk(KERN_ERR "%s%s: unexpected interrupt, "
+						"status=0x%02x, count=%ld\n",
+						hwif->name,
+						(hwif->next==hwgroup->hwif) ? "" : "(?)", stat, count);
+				}
+			}
+		}
+	} while ((hwif = hwif->next) != hwgroup->hwif);
+}
+
+/**
+ *	ide_intr	-	default IDE interrupt handler
+ *	@irq: interrupt number
+ *	@dev_id: hwif group
+ *	@regs: unused weirdness from the kernel irq layer
+ *
+ *	This is the default IRQ handler for the IDE layer. You should
+ *	not need to override it. If you do be aware it is subtle in
+ *	places
+ *
+ *	hwgroup->hwif is the interface in the group currently performing
+ *	a command. hwgroup->drive is the drive and hwgroup->handler is
+ *	the IRQ handler to call. As we issue a command the handlers
+ *	step through multiple states, reassigning the handler to the
+ *	next step in the process. Unlike a smart SCSI controller IDE
+ *	expects the main processor to sequence the various transfer
+ *	stages. We also manage a poll timer to catch up with most
+ *	timeout situations. There are still a few where the handlers
+ *	don't ever decide to give up.
+ *
+ *	The handler eventually returns ide_stopped to indicate the
+ *	request completed. At this point we issue the next request
+ *	on the hwgroup and the process begins again.
+ */
+ 
+void ide_intr (int irq, void *dev_id, struct pt_regs *regs)
+{
+	unsigned long flags;
+	ide_hwgroup_t *hwgroup = (ide_hwgroup_t *)dev_id;
+	ide_hwif_t *hwif;
+	ide_drive_t *drive;
+	ide_handler_t *handler;
+	ide_startstop_t startstop;
+
+	spin_lock_irqsave(&ide_lock, flags);
+	hwif = hwgroup->hwif;
+
+	if (!ide_ack_intr(hwif)) {
+		spin_unlock_irqrestore(&ide_lock, flags);
+		return;
+	}
+
+	if ((handler = hwgroup->handler) == NULL ||
+	    hwgroup->poll_timeout != 0) {
+		/*
+		 * Not expecting an interrupt from this drive.
+		 * That means this could be:
+		 *	(1) an interrupt from another PCI device
+		 *	sharing the same PCI INT# as us.
+		 * or	(2) a drive just entered sleep or standby mode,
+		 *	and is interrupting to let us know.
+		 * or	(3) a spurious interrupt of unknown origin.
+		 *
+		 * For PCI, we cannot tell the difference,
+		 * so in that case we just ignore it and hope it goes away.
+		 *
+		 * FIXME: unexpected_intr should be hwif-> then we can
+		 * remove all the ifdef PCI crap
+		 */
+#ifdef CONFIG_BLK_DEV_IDEPCI
+		if (hwif->pci_dev && !hwif->pci_dev->vendor)
+#endif	/* CONFIG_BLK_DEV_IDEPCI */
+		{
+			/*
+			 * Probably not a shared PCI interrupt,
+			 * so we can safely try to do something about it:
+			 */
+			unexpected_intr(irq, hwgroup);
+#ifdef CONFIG_BLK_DEV_IDEPCI
+		} else {
+			/*
+			 * Whack the status register, just in case
+			 * we have a leftover pending IRQ.
+			 */
+			(void) hwif->INB(hwif->io_ports[IDE_STATUS_OFFSET]);
+#endif /* CONFIG_BLK_DEV_IDEPCI */
+		}
+		spin_unlock_irqrestore(&ide_lock, flags);
+		return;
+	}
+	drive = hwgroup->drive;
+	if (!drive) {
+		/*
+		 * This should NEVER happen, and there isn't much
+		 * we could do about it here.
+		 *
+		 * [Note - this can occur if the drive is hot unplugged]
+		 */
+		spin_unlock_irqrestore(&ide_lock, flags);
+		return;
+	}
+	if (!drive_is_ready(drive)) {
+		/*
+		 * This happens regularly when we share a PCI IRQ with
+		 * another device.  Unfortunately, it can also happen
+		 * with some buggy drives that trigger the IRQ before
+		 * their status register is up to date.  Hopefully we have
+		 * enough advance overhead that the latter isn't a problem.
+		 */
+		spin_unlock_irqrestore(&ide_lock, flags);
+		return;
+	}
+	if (!hwgroup->busy) {
+		hwgroup->busy = 1;	/* paranoia */
+		printk(KERN_ERR "%s: ide_intr: hwgroup->busy was 0 ??\n", drive->name);
+	}
+	hwgroup->handler = NULL;
+	del_timer(&hwgroup->timer);
+	spin_unlock(&ide_lock);
+
+	if (drive->unmask)
+		local_irq_enable();
+	/* service this interrupt, may set handler for next interrupt */
+	startstop = handler(drive);
+	spin_lock_irq(&ide_lock);
+
+	/*
+	 * Note that handler() may have set things up for another
+	 * interrupt to occur soon, but it cannot happen until
+	 * we exit from this routine, because it will be the
+	 * same irq as is currently being serviced here, and Linux
+	 * won't allow another of the same (on any CPU) until we return.
+	 */
+	set_recovery_timer(HWIF(drive));
+	drive->service_time = jiffies - drive->service_start;
+	if (startstop == ide_stopped) {
+		if (hwgroup->handler == NULL) {	/* paranoia */
+			hwgroup->busy = 0;
+			ide_do_request(hwgroup, hwif->irq);
+		} else {
+			printk(KERN_ERR "%s: ide_intr: huh? expected NULL handler "
+				"on exit\n", drive->name);
+		}
+	}
+	spin_unlock_irqrestore(&ide_lock, flags);
+}
+
+EXPORT_SYMBOL(ide_intr);
+
+/**
+ *	ide_init_drive_cmd	-	initialize a drive command request
+ *	@rq: request object
+ *
+ *	Initialize a request before we fill it in and send it down to
+ *	ide_do_drive_cmd. Commands must be set up by this function. Right
+ *	now it doesn't do a lot, but if that changes abusers will have a
+ *	nasty suprise.
+ */
+
+void ide_init_drive_cmd (struct request *rq)
+{
+	memset(rq, 0, sizeof(*rq));
+	rq->flags = REQ_DRIVE_CMD;
+}
+
+EXPORT_SYMBOL(ide_init_drive_cmd);
+
+/**
+ *	ide_do_drive_cmd	-	issue IDE special command
+ *	@drive: device to issue command
+ *	@rq: request to issue
+ *	@action: action for processing
+ *
+ *	This function issues a special IDE device request
+ *	onto the request queue.
+ *
+ *	If action is ide_wait, then the rq is queued at the end of the
+ *	request queue, and the function sleeps until it has been processed.
+ *	This is for use when invoked from an ioctl handler.
+ *
+ *	If action is ide_preempt, then the rq is queued at the head of
+ *	the request queue, displacing the currently-being-processed
+ *	request and this function returns immediately without waiting
+ *	for the new rq to be completed.  This is VERY DANGEROUS, and is
+ *	intended for careful use by the ATAPI tape/cdrom driver code.
+ *
+ *	If action is ide_next, then the rq is queued immediately after
+ *	the currently-being-processed-request (if any), and the function
+ *	returns without waiting for the new rq to be completed.  As above,
+ *	This is VERY DANGEROUS, and is intended for careful use by the
+ *	ATAPI tape/cdrom driver code.
+ *
+ *	If action is ide_end, then the rq is queued at the end of the
+ *	request queue, and the function returns immediately without waiting
+ *	for the new rq to be completed. This is again intended for careful
+ *	use by the ATAPI tape/cdrom driver code.
+ */
+ 
+int ide_do_drive_cmd (ide_drive_t *drive, struct request *rq, ide_action_t action)
+{
+	unsigned long flags;
+	ide_hwgroup_t *hwgroup = HWGROUP(drive);
+	DECLARE_COMPLETION(wait);
+	int insert_end = 1, err;
+
+#ifdef CONFIG_BLK_DEV_PDC4030
+	/*
+	 *	FIXME: there should be a drive or hwif->special
+	 *	handler that points here by default, not hacks
+	 *	in the ide-io.c code
+	 */
+	if (HWIF(drive)->chipset == ide_pdc4030 && rq->buffer != NULL)
+		return -ENOSYS;  /* special drive cmds not supported */
+#endif
+	rq->errors = 0;
+	rq->rq_status = RQ_ACTIVE;
+
+	rq->rq_disk = drive->disk;
+
+	/*
+	 * we need to hold an extra reference to request for safe inspection
+	 * after completion
+	 */
+	if (action == ide_wait) {
+		rq->ref_count++;
+		rq->waiting = &wait;
+	}
+
+	spin_lock_irqsave(&ide_lock, flags);
+	if (action == ide_preempt) {
+		hwgroup->rq = NULL;
+		insert_end = 0;
+	}
+	__elv_add_request(&drive->queue, rq, insert_end, 0);
+	ide_do_request(hwgroup, 0);
+	spin_unlock_irqrestore(&ide_lock, flags);
+
+	err = 0;
+	if (action == ide_wait) {
+		wait_for_completion(&wait);
+		if (rq->errors)
+			err = -EIO;
+
+		blk_put_request(rq);
+	}
+
+	return err;
+}
+
+EXPORT_SYMBOL(ide_do_drive_cmd);