libata.h

/*
 *  Copyright 2003-2005 Red Hat, Inc.  All rights reserved.
 *  Copyright 2003-2005 Jeff Garzik
 *
 *
 *  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.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; see the file COPYING.  If not, write to
 *  the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 *
 *  libata documentation is available via 'make {ps|pdf}docs',
 *  as Documentation/DocBook/libata.*
 *
 */

#ifndef __LINUX_LIBATA_H__
#define __LINUX_LIBATA_H__

#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/pci.h>
#include <linux/dma-mapping.h>
#include <asm/io.h>
#include <linux/ata.h>
#include <linux/workqueue.h>

/*
 * compile-time options
 */
#undef ATA_DEBUG		/* debugging output */
#undef ATA_VERBOSE_DEBUG	/* yet more debugging output */
#undef ATA_IRQ_TRAP		/* define to ack screaming irqs */
#undef ATA_NDEBUG		/* define to disable quick runtime checks */
#undef ATA_ENABLE_PATA		/* define to enable PATA support in some
				 * low-level drivers */
#undef ATAPI_ENABLE_DMADIR	/* enables ATAPI DMADIR bridge support */


/* note: prints function name for you */
#ifdef ATA_DEBUG
#define DPRINTK(fmt, args...) printk(KERN_ERR "%s: " fmt, __FUNCTION__, ## args)
#ifdef ATA_VERBOSE_DEBUG
#define VPRINTK(fmt, args...) printk(KERN_ERR "%s: " fmt, __FUNCTION__, ## args)
#else
#define VPRINTK(fmt, args...)
#endif	/* ATA_VERBOSE_DEBUG */
#else
#define DPRINTK(fmt, args...)
#define VPRINTK(fmt, args...)
#endif	/* ATA_DEBUG */

#define BPRINTK(fmt, args...) if (ap->flags & ATA_FLAG_DEBUGMSG) printk(KERN_ERR "%s: " fmt, __FUNCTION__, ## args)

#ifdef ATA_NDEBUG
#define assert(expr)
#else
#define assert(expr) \
        if(unlikely(!(expr))) {                                   \
        printk(KERN_ERR "Assertion failed! %s,%s,%s,line=%d\n", \
        #expr,__FILE__,__FUNCTION__,__LINE__);          \
        }
#endif

/* defines only for the constants which don't work well as enums */
#define ATA_TAG_POISON		0xfafbfcfdU

/* move to PCI layer? */
static inline struct device *pci_dev_to_dev(struct pci_dev *pdev)
{
	return &pdev->dev;
}

enum {
	/* various global constants */
	LIBATA_MAX_PRD		= ATA_MAX_PRD / 2,
	ATA_MAX_PORTS		= 8,
	ATA_DEF_QUEUE		= 1,
	ATA_MAX_QUEUE		= 1,
	ATA_MAX_SECTORS		= 200,	/* FIXME */
	ATA_MAX_BUS		= 2,
	ATA_DEF_BUSY_WAIT	= 10000,
	ATA_SHORT_PAUSE		= (HZ >> 6) + 1,

	ATA_SHT_EMULATED	= 1,
	ATA_SHT_CMD_PER_LUN	= 1,
	ATA_SHT_THIS_ID		= -1,
	ATA_SHT_USE_CLUSTERING	= 1,

	/* struct ata_device stuff */
	ATA_DFLAG_LBA48		= (1 << 0), /* device supports LBA48 */
	ATA_DFLAG_PIO		= (1 << 1), /* device currently in PIO mode */
	ATA_DFLAG_LOCK_SECTORS	= (1 << 2), /* don't adjust max_sectors */
	ATA_DFLAG_LBA		= (1 << 3), /* device supports LBA */

	ATA_DEV_UNKNOWN		= 0,	/* unknown device */
	ATA_DEV_ATA		= 1,	/* ATA device */
	ATA_DEV_ATA_UNSUP	= 2,	/* ATA device (unsupported) */
	ATA_DEV_ATAPI		= 3,	/* ATAPI device */
	ATA_DEV_ATAPI_UNSUP	= 4,	/* ATAPI device (unsupported) */
	ATA_DEV_NONE		= 5,	/* no device */

	/* struct ata_port flags */
	ATA_FLAG_SLAVE_POSS	= (1 << 1), /* host supports slave dev */
					    /* (doesn't imply presence) */
	ATA_FLAG_PORT_DISABLED	= (1 << 2), /* port is disabled, ignore it */
	ATA_FLAG_SATA		= (1 << 3),
	ATA_FLAG_NO_LEGACY	= (1 << 4), /* no legacy mode check */
	ATA_FLAG_SRST		= (1 << 5), /* use ATA SRST, not E.D.D. */
	ATA_FLAG_MMIO		= (1 << 6), /* use MMIO, not PIO */
	ATA_FLAG_SATA_RESET	= (1 << 7), /* use COMRESET */
	ATA_FLAG_PIO_DMA	= (1 << 8), /* PIO cmds via DMA */
	ATA_FLAG_NOINTR		= (1 << 9), /* FIXME: Remove this once
					     * proper HSM is in place. */
	ATA_FLAG_DEBUGMSG	= (1 << 10),

	ATA_QCFLAG_ACTIVE	= (1 << 1), /* cmd not yet ack'd to scsi lyer */
	ATA_QCFLAG_SG		= (1 << 3), /* have s/g table? */
	ATA_QCFLAG_SINGLE	= (1 << 4), /* no s/g, just a single buffer */
	ATA_QCFLAG_DMAMAP	= ATA_QCFLAG_SG | ATA_QCFLAG_SINGLE,

	/* various lengths of time */
	ATA_TMOUT_EDD		= 5 * HZ,	/* hueristic */
	ATA_TMOUT_PIO		= 30 * HZ,
	ATA_TMOUT_BOOT		= 30 * HZ,	/* hueristic */
	ATA_TMOUT_BOOT_QUICK	= 7 * HZ,	/* hueristic */
	ATA_TMOUT_CDB		= 30 * HZ,
	ATA_TMOUT_CDB_QUICK	= 5 * HZ,

	/* ATA bus states */
	BUS_UNKNOWN		= 0,
	BUS_DMA			= 1,
	BUS_IDLE		= 2,
	BUS_NOINTR		= 3,
	BUS_NODATA		= 4,
	BUS_TIMER		= 5,
	BUS_PIO			= 6,
	BUS_EDD			= 7,
	BUS_IDENTIFY		= 8,
	BUS_PACKET		= 9,

	/* SATA port states */
	PORT_UNKNOWN		= 0,
	PORT_ENABLED		= 1,
	PORT_DISABLED		= 2,

	/* encoding various smaller bitmaps into a single
	 * unsigned long bitmap
	 */
	ATA_SHIFT_UDMA		= 0,
	ATA_SHIFT_MWDMA		= 8,
	ATA_SHIFT_PIO		= 11,

	/* size of buffer to pad xfers ending on unaligned boundaries */
	ATA_DMA_PAD_SZ		= 4,
	ATA_DMA_PAD_BUF_SZ	= ATA_DMA_PAD_SZ * ATA_MAX_QUEUE,
	
	/* Masks for port functions */
	ATA_PORT_PRIMARY	= (1 << 0),
	ATA_PORT_SECONDARY	= (1 << 1),
};

enum hsm_task_states {
	HSM_ST_UNKNOWN,
	HSM_ST_IDLE,
	HSM_ST_POLL,
	HSM_ST_TMOUT,
	HSM_ST,
	HSM_ST_LAST,
	HSM_ST_LAST_POLL,
	HSM_ST_ERR,
};

enum ata_completion_errors {
	AC_ERR_OTHER		= (1 << 0),
	AC_ERR_DEV		= (1 << 1),
	AC_ERR_ATA_BUS		= (1 << 2),
	AC_ERR_HOST_BUS		= (1 << 3),
};

/* forward declarations */
struct scsi_device;
struct ata_port_operations;
struct ata_port;
struct ata_queued_cmd;

/* typedefs */
typedef int (*ata_qc_cb_t) (struct ata_queued_cmd *qc, unsigned int err_mask);

struct ata_ioports {
	unsigned long		cmd_addr;
	unsigned long		data_addr;
	unsigned long		error_addr;
	unsigned long		feature_addr;
	unsigned long		nsect_addr;
	unsigned long		lbal_addr;
	unsigned long		lbam_addr;
	unsigned long		lbah_addr;
	unsigned long		device_addr;
	unsigned long		status_addr;
	unsigned long		command_addr;
	unsigned long		altstatus_addr;
	unsigned long		ctl_addr;
	unsigned long		bmdma_addr;
	unsigned long		scr_addr;
};

struct ata_probe_ent {
	struct list_head	node;
	struct device 		*dev;
	const struct ata_port_operations *port_ops;
	struct scsi_host_template *sht;
	struct ata_ioports	port[ATA_MAX_PORTS];
	unsigned int		n_ports;
	unsigned int		hard_port_no;
	unsigned int		pio_mask;
	unsigned int		mwdma_mask;
	unsigned int		udma_mask;
	unsigned int		legacy_mode;
	unsigned long		irq;
	unsigned int		irq_flags;
	unsigned long		host_flags;
	void __iomem		*mmio_base;
	void			*private_data;
};

struct ata_host_set {
	spinlock_t		lock;
	struct device 		*dev;
	unsigned long		irq;
	void __iomem		*mmio_base;
	unsigned int		n_ports;
	void			*private_data;
	const struct ata_port_operations *ops;
	struct ata_port *	ports[0];
};

struct ata_queued_cmd {
	struct ata_port		*ap;
	struct ata_device	*dev;

	struct scsi_cmnd	*scsicmd;
	void			(*scsidone)(struct scsi_cmnd *);

	struct ata_taskfile	tf;
	u8			cdb[ATAPI_CDB_LEN];

	unsigned long		flags;		/* ATA_QCFLAG_xxx */
	unsigned int		tag;
	unsigned int		n_elem;
	unsigned int		orig_n_elem;

	int			dma_dir;

	unsigned int		pad_len;

	unsigned int		nsect;
	unsigned int		cursect;

	unsigned int		nbytes;
	unsigned int		curbytes;

	unsigned int		cursg;
	unsigned int		cursg_ofs;

	struct scatterlist	sgent;
	struct scatterlist	pad_sgent;
	void			*buf_virt;

	/* DO NOT iterate over __sg manually, use ata_for_each_sg() */
	struct scatterlist	*__sg;

	ata_qc_cb_t		complete_fn;

	struct completion	*waiting;

	void			*private_data;
};

struct ata_host_stats {
	unsigned long		unhandled_irq;
	unsigned long		idle_irq;
	unsigned long		rw_reqbuf;
};

struct ata_device {
	u64			n_sectors;	/* size of device, if ATA */
	unsigned long		flags;		/* ATA_DFLAG_xxx */
	unsigned int		class;		/* ATA_DEV_xxx */
	unsigned int		devno;		/* 0 or 1 */
	u16			id[ATA_ID_WORDS]; /* IDENTIFY xxx DEVICE data */
	u8			pio_mode;
	u8			dma_mode;
	u8			xfer_mode;
	unsigned int		xfer_shift;	/* ATA_SHIFT_xxx */

	unsigned int		multi_count;	/* sectors count for
						   READ/WRITE MULTIPLE */

	/* for CHS addressing */
	u16			cylinders;	/* Number of cylinders */
	u16			heads;		/* Number of heads */
	u16			sectors;	/* Number of sectors per track */
};

struct ata_port {
	struct Scsi_Host	*host;	/* our co-allocated scsi host */
	const struct ata_port_operations *ops;
	unsigned long		flags;	/* ATA_FLAG_xxx */
	unsigned int		id;	/* unique id req'd by scsi midlyr */
	unsigned int		port_no; /* unique port #; from zero */
	unsigned int		hard_port_no;	/* hardware port #; from zero */

	struct ata_prd		*prd;	 /* our SG list */
	dma_addr_t		prd_dma; /* and its DMA mapping */

	void			*pad;	/* array of DMA pad buffers */
	dma_addr_t		pad_dma;

	struct ata_ioports	ioaddr;	/* ATA cmd/ctl/dma register blocks */

	u8			ctl;	/* cache of ATA control register */
	u8			last_ctl;	/* Cache last written value */
	unsigned int		bus_state;
	unsigned int		port_state;
	unsigned int		pio_mask;
	unsigned int		mwdma_mask;
	unsigned int		udma_mask;
	unsigned int		cbl;	/* cable type; ATA_CBL_xxx */
	unsigned int		cdb_len;

	struct ata_device	device[ATA_MAX_DEVICES];

	struct ata_queued_cmd	qcmd[ATA_MAX_QUEUE];
	unsigned long		qactive;
	unsigned int		active_tag;

	struct ata_host_stats	stats;
	struct ata_host_set	*host_set;

	struct work_struct	packet_task;

	struct work_struct	pio_task;
	unsigned int		hsm_task_state;
	unsigned long		pio_task_timeout;

	void			*private_data;
};

struct ata_port_operations {
	void (*port_disable) (struct ata_port *);

	void (*dev_config) (struct ata_port *, struct ata_device *);

	void (*set_piomode) (struct ata_port *, struct ata_device *);
	void (*set_dmamode) (struct ata_port *, struct ata_device *);

	void (*tf_load) (struct ata_port *ap, const struct ata_taskfile *tf);
	void (*tf_read) (struct ata_port *ap, struct ata_taskfile *tf);

	void (*exec_command)(struct ata_port *ap, const struct ata_taskfile *tf);
	u8   (*check_status)(struct ata_port *ap);
	u8   (*check_altstatus)(struct ata_port *ap);
	void (*dev_select)(struct ata_port *ap, unsigned int device);

	void (*phy_reset) (struct ata_port *ap);
	void (*post_set_mode) (struct ata_port *ap);

	int (*check_atapi_dma) (struct ata_queued_cmd *qc);

	void (*bmdma_setup) (struct ata_queued_cmd *qc);
	void (*bmdma_start) (struct ata_queued_cmd *qc);

	void (*qc_prep) (struct ata_queued_cmd *qc);
	int (*qc_issue) (struct ata_queued_cmd *qc);

	void (*eng_timeout) (struct ata_port *ap);

	irqreturn_t (*irq_handler)(int, void *, struct pt_regs *);
	void (*irq_clear) (struct ata_port *);

	u32 (*scr_read) (struct ata_port *ap, unsigned int sc_reg);
	void (*scr_write) (struct ata_port *ap, unsigned int sc_reg,
			   u32 val);

	int (*port_start) (struct ata_port *ap);
	void (*port_stop) (struct ata_port *ap);

	void (*host_stop) (struct ata_host_set *host_set);

	void (*bmdma_stop) (struct ata_queued_cmd *qc);
	u8   (*bmdma_status) (struct ata_port *ap);
};

struct ata_port_info {
	struct scsi_host_template	*sht;
	unsigned long		host_flags;
	unsigned long		pio_mask;
	unsigned long		mwdma_mask;
	unsigned long		udma_mask;
	const struct ata_port_operations *port_ops;
	void 			*private_data;
};

struct ata_timing {
	unsigned short mode;		/* ATA mode */
	unsigned short setup;		/* t1 */
	unsigned short act8b;		/* t2 for 8-bit I/O */
	unsigned short rec8b;		/* t2i for 8-bit I/O */
	unsigned short cyc8b;		/* t0 for 8-bit I/O */
	unsigned short active;		/* t2 or tD */
	unsigned short recover;		/* t2i or tK */
	unsigned short cycle;		/* t0 */
	unsigned short udma;		/* t2CYCTYP/2 */
};

#define FIT(v,vmin,vmax)	max_t(short,min_t(short,v,vmax),vmin)

extern void ata_port_probe(struct ata_port *);
extern void __sata_phy_reset(struct ata_port *ap);
extern void sata_phy_reset(struct ata_port *ap);
extern void ata_bus_reset(struct ata_port *ap);
extern void ata_port_disable(struct ata_port *);
extern void ata_std_ports(struct ata_ioports *ioaddr);
#ifdef CONFIG_PCI
extern int ata_pci_init_one (struct pci_dev *pdev, struct ata_port_info **port_info,
			     unsigned int n_ports);
extern void ata_pci_remove_one (struct pci_dev *pdev);
#endif /* CONFIG_PCI */
extern int ata_device_add(const struct ata_probe_ent *ent);
extern void ata_host_set_remove(struct ata_host_set *host_set);
extern int ata_scsi_detect(struct scsi_host_template *sht);
extern int ata_scsi_ioctl(struct scsi_device *dev, int cmd, void __user *arg);
extern int ata_scsi_queuecmd(struct scsi_cmnd *cmd, void (*done)(struct scsi_cmnd *));
extern int ata_scsi_error(struct Scsi_Host *host);
extern int ata_scsi_release(struct Scsi_Host *host);
extern unsigned int ata_host_intr(struct ata_port *ap, struct ata_queued_cmd *qc);
extern int ata_ratelimit(void);

/*
 * Default driver ops implementations
 */
extern void ata_tf_load(struct ata_port *ap, const struct ata_taskfile *tf);
extern void ata_tf_read(struct ata_port *ap, struct ata_taskfile *tf);
extern void ata_tf_to_fis(const struct ata_taskfile *tf, u8 *fis, u8 pmp);
extern void ata_tf_from_fis(const u8 *fis, struct ata_taskfile *tf);
extern void ata_noop_dev_select (struct ata_port *ap, unsigned int device);
extern void ata_std_dev_select (struct ata_port *ap, unsigned int device);
extern u8 ata_check_status(struct ata_port *ap);
extern u8 ata_altstatus(struct ata_port *ap);
extern void ata_exec_command(struct ata_port *ap, const struct ata_taskfile *tf);
extern int ata_port_start (struct ata_port *ap);
extern void ata_port_stop (struct ata_port *ap);
extern void ata_host_stop (struct ata_host_set *host_set);
extern irqreturn_t ata_interrupt (int irq, void *dev_instance, struct pt_regs *regs);
extern void ata_qc_prep(struct ata_queued_cmd *qc);
extern int ata_qc_issue_prot(struct ata_queued_cmd *qc);
extern void ata_sg_init_one(struct ata_queued_cmd *qc, void *buf,
		unsigned int buflen);
extern void ata_sg_init(struct ata_queued_cmd *qc, struct scatterlist *sg,
		 unsigned int n_elem);
extern unsigned int ata_dev_classify(const struct ata_taskfile *tf);
extern void ata_dev_id_string(const u16 *id, unsigned char *s,
			      unsigned int ofs, unsigned int len);
extern void ata_dev_config(struct ata_port *ap, unsigned int i);
extern void ata_bmdma_setup (struct ata_queued_cmd *qc);
extern void ata_bmdma_start (struct ata_queued_cmd *qc);
extern void ata_bmdma_stop(struct ata_queued_cmd *qc);
extern u8   ata_bmdma_status(struct ata_port *ap);
extern void ata_bmdma_irq_clear(struct ata_port *ap);
extern void ata_qc_complete(struct ata_queued_cmd *qc, unsigned int err_mask);
extern void ata_eng_timeout(struct ata_port *ap);
extern void ata_scsi_simulate(u16 *id, struct scsi_cmnd *cmd,
			      void (*done)(struct scsi_cmnd *));
extern int ata_std_bios_param(struct scsi_device *sdev,
			      struct block_device *bdev,
			      sector_t capacity, int geom[]);
extern int ata_scsi_slave_config(struct scsi_device *sdev);

/*
 * Timing helpers
 */
extern int ata_timing_compute(struct ata_device *, unsigned short,
			      struct ata_timing *, int, int);
extern void ata_timing_merge(const struct ata_timing *,
			     const struct ata_timing *, struct ata_timing *,
			     unsigned int);

enum {
	ATA_TIMING_SETUP	= (1 << 0),
	ATA_TIMING_ACT8B	= (1 << 1),
	ATA_TIMING_REC8B	= (1 << 2),
	ATA_TIMING_CYC8B	= (1 << 3),
	ATA_TIMING_8BIT		= ATA_TIMING_ACT8B | ATA_TIMING_REC8B |
				  ATA_TIMING_CYC8B,
	ATA_TIMING_ACTIVE	= (1 << 4),
	ATA_TIMING_RECOVER	= (1 << 5),
	ATA_TIMING_CYCLE	= (1 << 6),
	ATA_TIMING_UDMA		= (1 << 7),
	ATA_TIMING_ALL		= ATA_TIMING_SETUP | ATA_TIMING_ACT8B |
				  ATA_TIMING_REC8B | ATA_TIMING_CYC8B |
				  ATA_TIMING_ACTIVE | ATA_TIMING_RECOVER |
				  ATA_TIMING_CYCLE | ATA_TIMING_UDMA,
};


#ifdef CONFIG_PCI
struct pci_bits {
	unsigned int		reg;	/* PCI config register to read */
	unsigned int		width;	/* 1 (8 bit), 2 (16 bit), 4 (32 bit) */
	unsigned long		mask;
	unsigned long		val;
};

extern void ata_pci_host_stop (struct ata_host_set *host_set);
extern struct ata_probe_ent *
ata_pci_init_native_mode(struct pci_dev *pdev, struct ata_port_info **port, int portmask);
extern int pci_test_config_bits(struct pci_dev *pdev, const struct pci_bits *bits);

#endif /* CONFIG_PCI */


static inline int
ata_sg_is_last(struct scatterlist *sg, struct ata_queued_cmd *qc)
{
	if (sg == &qc->pad_sgent)
		return 1;
	if (qc->pad_len)
		return 0;
	if (((sg - qc->__sg) + 1) == qc->n_elem)
		return 1;
	return 0;
}

static inline struct scatterlist *
ata_qc_next_sg(struct scatterlist *sg, struct ata_queued_cmd *qc)
{
	if (sg == &qc->pad_sgent)
		return NULL;
	if (++sg - qc->__sg < qc->n_elem)
		return sg;
	return qc->pad_len ? &qc->pad_sgent : NULL;
}

#define ata_for_each_sg(sg, qc) \
	for (sg = qc->__sg; sg; sg = ata_qc_next_sg(sg, qc))

static inline unsigned int ata_tag_valid(unsigned int tag)
{
	return (tag < ATA_MAX_QUEUE) ? 1 : 0;
}

static inline unsigned int ata_dev_present(const struct ata_device *dev)
{
	return ((dev->class == ATA_DEV_ATA) ||
		(dev->class == ATA_DEV_ATAPI));
}

static inline u8 ata_chk_status(struct ata_port *ap)
{
	return ap->ops->check_status(ap);
}


/**
 *	ata_pause - Flush writes and pause 400 nanoseconds.
 *	@ap: Port to wait for.
 *
 *	LOCKING:
 *	Inherited from caller.
 */

static inline void ata_pause(struct ata_port *ap)
{
	ata_altstatus(ap);
	ndelay(400);
}


/**
 *	ata_busy_wait - Wait for a port status register
 *	@ap: Port to wait for.
 *
 *	Waits up to max*10 microseconds for the selected bits in the port's
 *	status register to be cleared.
 *	Returns final value of status register.
 *
 *	LOCKING:
 *	Inherited from caller.
 */

static inline u8 ata_busy_wait(struct ata_port *ap, unsigned int bits,
			       unsigned int max)
{
	u8 status;

	do {
		udelay(10);
		status = ata_chk_status(ap);
		max--;
	} while ((status & bits) && (max > 0));

	return status;
}


/**
 *	ata_wait_idle - Wait for a port to be idle.
 *	@ap: Port to wait for.
 *
 *	Waits up to 10ms for port's BUSY and DRQ signals to clear.
 *	Returns final value of status register.
 *
 *	LOCKING:
 *	Inherited from caller.
 */

static inline u8 ata_wait_idle(struct ata_port *ap)
{
	u8 status = ata_busy_wait(ap, ATA_BUSY | ATA_DRQ, 1000);

	if (status & (ATA_BUSY | ATA_DRQ)) {
		unsigned long l = ap->ioaddr.status_addr;
		printk(KERN_WARNING
		       "ATA: abnormal status 0x%X on port 0x%lX\n",
		       status, l);
	}

	return status;
}

static inline void ata_qc_set_polling(struct ata_queued_cmd *qc)
{
	qc->tf.ctl |= ATA_NIEN;
}

static inline struct ata_queued_cmd *ata_qc_from_tag (struct ata_port *ap,
						      unsigned int tag)
{
	if (likely(ata_tag_valid(tag)))
		return &ap->qcmd[tag];
	return NULL;
}

static inline void ata_tf_init(struct ata_port *ap, struct ata_taskfile *tf, unsigned int device)
{
	memset(tf, 0, sizeof(*tf));

	tf->ctl = ap->ctl;
	if (device == 0)
		tf->device = ATA_DEVICE_OBS;
	else
		tf->device = ATA_DEVICE_OBS | ATA_DEV1;
}

static inline void ata_qc_reinit(struct ata_queued_cmd *qc)
{
	qc->__sg = NULL;
	qc->flags = 0;
	qc->cursect = qc->cursg = qc->cursg_ofs = 0;
	qc->nsect = 0;
	qc->nbytes = qc->curbytes = 0;

	ata_tf_init(qc->ap, &qc->tf, qc->dev->devno);
}


/**
 *	ata_irq_on - Enable interrupts on a port.
 *	@ap: Port on which interrupts are enabled.
 *
 *	Enable interrupts on a legacy IDE device using MMIO or PIO,
 *	wait for idle, clear any pending interrupts.
 *
 *	LOCKING:
 *	Inherited from caller.
 */

static inline u8 ata_irq_on(struct ata_port *ap)
{
	struct ata_ioports *ioaddr = &ap->ioaddr;
	u8 tmp;

	ap->ctl &= ~ATA_NIEN;
	ap->last_ctl = ap->ctl;

	if (ap->flags & ATA_FLAG_MMIO)
		writeb(ap->ctl, (void __iomem *) ioaddr->ctl_addr);
	else
		outb(ap->ctl, ioaddr->ctl_addr);
	tmp = ata_wait_idle(ap);

	ap->ops->irq_clear(ap);

	return tmp;
}


/**
 *	ata_irq_ack - Acknowledge a device interrupt.
 *	@ap: Port on which interrupts are enabled.
 *
 *	Wait up to 10 ms for legacy IDE device to become idle (BUSY
 *	or BUSY+DRQ clear).  Obtain dma status and port status from
 *	device.  Clear the interrupt.  Return port status.
 *
 *	LOCKING:
 */

static inline u8 ata_irq_ack(struct ata_port *ap, unsigned int chk_drq)
{
	unsigned int bits = chk_drq ? ATA_BUSY | ATA_DRQ : ATA_BUSY;
	u8 host_stat, post_stat, status;

	status = ata_busy_wait(ap, bits, 1000);
	if (status & bits)
		DPRINTK("abnormal status 0x%X\n", status);

	/* get controller status; clear intr, err bits */
	if (ap->flags & ATA_FLAG_MMIO) {
		void __iomem *mmio = (void __iomem *) ap->ioaddr.bmdma_addr;
		host_stat = readb(mmio + ATA_DMA_STATUS);
		writeb(host_stat | ATA_DMA_INTR | ATA_DMA_ERR,
		       mmio + ATA_DMA_STATUS);

		post_stat = readb(mmio + ATA_DMA_STATUS);
	} else {
		host_stat = inb(ap->ioaddr.bmdma_addr + ATA_DMA_STATUS);
		outb(host_stat | ATA_DMA_INTR | ATA_DMA_ERR,
		     ap->ioaddr.bmdma_addr + ATA_DMA_STATUS);

		post_stat = inb(ap->ioaddr.bmdma_addr + ATA_DMA_STATUS);
	}

	VPRINTK("irq ack: host_stat 0x%X, new host_stat 0x%X, drv_stat 0x%X\n",
		host_stat, post_stat, status);

	return status;
}

static inline u32 scr_read(struct ata_port *ap, unsigned int reg)
{
	return ap->ops->scr_read(ap, reg);
}

static inline void scr_write(struct ata_port *ap, unsigned int reg, u32 val)
{
	ap->ops->scr_write(ap, reg, val);
}

static inline void scr_write_flush(struct ata_port *ap, unsigned int reg,
				   u32 val)
{
	ap->ops->scr_write(ap, reg, val);
	(void) ap->ops->scr_read(ap, reg);
}

static inline unsigned int sata_dev_present(struct ata_port *ap)
{
	return ((scr_read(ap, SCR_STATUS) & 0xf) == 0x3) ? 1 : 0;
}

static inline int ata_try_flush_cache(const struct ata_device *dev)
{
	return ata_id_wcache_enabled(dev->id) ||
	       ata_id_has_flush(dev->id) ||
	       ata_id_has_flush_ext(dev->id);
}

static inline unsigned int ac_err_mask(u8 status)
{
	if (status & ATA_BUSY)
		return AC_ERR_ATA_BUS;
	if (status & (ATA_ERR | ATA_DF))
		return AC_ERR_DEV;
	return 0;
}

static inline unsigned int __ac_err_mask(u8 status)
{
	unsigned int mask = ac_err_mask(status);
	if (mask == 0)
		return AC_ERR_OTHER;
	return mask;
}

static inline int ata_pad_alloc(struct ata_port *ap, struct device *dev)
{
	ap->pad_dma = 0;
	ap->pad = dma_alloc_coherent(dev, ATA_DMA_PAD_BUF_SZ,
				     &ap->pad_dma, GFP_KERNEL);
	return (ap->pad == NULL) ? -ENOMEM : 0;
}

static inline void ata_pad_free(struct ata_port *ap, struct device *dev)
{
	dma_free_coherent(dev, ATA_DMA_PAD_BUF_SZ, ap->pad, ap->pad_dma);
}

#endif /* __LINUX_LIBATA_H__ */