/*
   *  IDE DMA support (including IDE PCI BM-DMA).
   *
   *  Copyright (C) 1995-1998   Mark Lord
   *  Copyright (C) 1999-2000   Andre Hedrick <andre@linux-ide.org>
   *  Copyright (C) 2004, 2007  Bartlomiej Zolnierkiewicz
   *
   *  May be copied or modified under the terms of the GNU General Public License
   *
   *  DMA is supported for all IDE devices (disk drives, cdroms, tapes, floppies).
   */
  
  /*
   *  Special Thanks to Mark for his Six years of work.
   */
  
  /*
   * Thanks to "Christopher J. Reimer" <reimer@doe.carleton.ca> for
   * fixing the problem with the BIOS on some Acer motherboards.
   *
   * Thanks to "Benoit Poulot-Cazajous" <poulot@chorus.fr> for testing
   * "TX" chipset compatibility and for providing patches for the "TX" chipset.
   *
   * Thanks to Christian Brunner <chb@muc.de> for taking a good first crack
   * at generic DMA -- his patches were referred to when preparing this code.
   *
   * Most importantly, thanks to Robert Bringman <rob@mars.trion.com>
   * for supplying a Promise UDMA board & WD UDMA drive for this work!
   */
  
  #include <linux/types.h>
  #include <linux/gfp.h>
  #include <linux/kernel.h>
  #include <linux/export.h>
  #include <linux/ide.h>
  #include <linux/scatterlist.h>
  #include <linux/dma-mapping.h>
  
  static const struct drive_list_entry drive_whitelist[] = {
  	{ "Micropolis 2112A"	,       NULL		},
  	{ "CONNER CTMA 4000"	,       NULL		},
  	{ "CONNER CTT8000-A"	,       NULL		},
  	{ "ST34342A"		,	NULL		},
  	{ NULL			,	NULL		}
  };
  
  static const struct drive_list_entry drive_blacklist[] = {
  	{ "WDC AC11000H"	,	NULL 		},
  	{ "WDC AC22100H"	,	NULL 		},
  	{ "WDC AC32500H"	,	NULL 		},
  	{ "WDC AC33100H"	,	NULL 		},
  	{ "WDC AC31600H"	,	NULL 		},
  	{ "WDC AC32100H"	,	"24.09P07"	},
  	{ "WDC AC23200L"	,	"21.10N21"	},
  	{ "Compaq CRD-8241B"	,	NULL 		},
  	{ "CRD-8400B"		,	NULL 		},
  	{ "CRD-8480B",			NULL 		},
  	{ "CRD-8482B",			NULL 		},
  	{ "CRD-84"		,	NULL 		},
  	{ "SanDisk SDP3B"	,	NULL 		},
  	{ "SanDisk SDP3B-64"	,	NULL 		},
  	{ "SANYO CD-ROM CRD"	,	NULL 		},
  	{ "HITACHI CDR-8"	,	NULL 		},
  	{ "HITACHI CDR-8335"	,	NULL 		},
  	{ "HITACHI CDR-8435"	,	NULL 		},
  	{ "Toshiba CD-ROM XM-6202B"	,	NULL 		},
  	{ "TOSHIBA CD-ROM XM-1702BC",	NULL 		},
  	{ "CD-532E-A"		,	NULL 		},
  	{ "E-IDE CD-ROM CR-840",	NULL 		},
  	{ "CD-ROM Drive/F5A",	NULL 		},
  	{ "WPI CDD-820",		NULL 		},
  	{ "SAMSUNG CD-ROM SC-148C",	NULL 		},
  	{ "SAMSUNG CD-ROM SC",	NULL 		},
  	{ "ATAPI CD-ROM DRIVE 40X MAXIMUM",	NULL 		},
  	{ "_NEC DV5800A",               NULL            },
  	{ "SAMSUNG CD-ROM SN-124",	"N001" },
  	{ "Seagate STT20000A",		NULL  },
  	{ "CD-ROM CDR_U200",		"1.09" },
  	{ NULL			,	NULL		}
  
  };
  
  /**
   *	ide_dma_intr	-	IDE DMA interrupt handler
   *	@drive: the drive the interrupt is for
   *
   *	Handle an interrupt completing a read/write DMA transfer on an
   *	IDE device
   */
  
  ide_startstop_t ide_dma_intr(ide_drive_t *drive)
  {
  	ide_hwif_t *hwif = drive->hwif;
  	struct ide_cmd *cmd = &hwif->cmd;
  	u8 stat = 0, dma_stat = 0;
  
  	drive->waiting_for_dma = 0;
  	dma_stat = hwif->dma_ops->dma_end(drive);
  	ide_dma_unmap_sg(drive, cmd);
  	stat = hwif->tp_ops->read_status(hwif);
  
  	if (OK_STAT(stat, DRIVE_READY, drive->bad_wstat | ATA_DRQ)) {
  		if (!dma_stat) {
  			if ((cmd->tf_flags & IDE_TFLAG_FS) == 0)
  				ide_finish_cmd(drive, cmd, stat);
  			else
  				ide_complete_rq(drive, 0,
  						blk_rq_sectors(cmd->rq) << 9);
  			return ide_stopped;
  		}
  		printk(KERN_ERR "%s: %s: bad DMA status (0x%02x)
  ",
  			drive->name, __func__, dma_stat);
  	}
  	return ide_error(drive, "dma_intr", stat);
  }
  
  int ide_dma_good_drive(ide_drive_t *drive)
  {
  	return ide_in_drive_list(drive->id, drive_whitelist);
  }
  
  /**
   *	ide_dma_map_sg	-	map IDE scatter gather for DMA I/O
   *	@drive: the drive to map the DMA table for
   *	@cmd: command
   *
   *	Perform the DMA mapping magic necessary to access the source or
   *	target buffers of a request via DMA.  The lower layers of the
   *	kernel provide the necessary cache management so that we can
   *	operate in a portable fashion.
   */
  
  static int ide_dma_map_sg(ide_drive_t *drive, struct ide_cmd *cmd)
  {
  	ide_hwif_t *hwif = drive->hwif;
  	struct scatterlist *sg = hwif->sg_table;
  	int i;
  
  	if (cmd->tf_flags & IDE_TFLAG_WRITE)
  		cmd->sg_dma_direction = DMA_TO_DEVICE;
  	else
  		cmd->sg_dma_direction = DMA_FROM_DEVICE;
  
  	i = dma_map_sg(hwif->dev, sg, cmd->sg_nents, cmd->sg_dma_direction);
  	if (i) {
  		cmd->orig_sg_nents = cmd->sg_nents;
  		cmd->sg_nents = i;
  	}
  
  	return i;
  }
  
  /**
   *	ide_dma_unmap_sg	-	clean up DMA mapping
   *	@drive: The drive to unmap
   *
   *	Teardown mappings after DMA has completed. This must be called
   *	after the completion of each use of ide_build_dmatable and before
   *	the next use of ide_build_dmatable. Failure to do so will cause
   *	an oops as only one mapping can be live for each target at a given
   *	time.
   */
  
  void ide_dma_unmap_sg(ide_drive_t *drive, struct ide_cmd *cmd)
  {
  	ide_hwif_t *hwif = drive->hwif;
  
  	dma_unmap_sg(hwif->dev, hwif->sg_table, cmd->orig_sg_nents,
  		     cmd->sg_dma_direction);
  }
  EXPORT_SYMBOL_GPL(ide_dma_unmap_sg);
  
  /**
   *	ide_dma_off_quietly	-	Generic DMA kill
   *	@drive: drive to control
   *
   *	Turn off the current DMA on this IDE controller.
   */
  
  void ide_dma_off_quietly(ide_drive_t *drive)
  {
  	drive->dev_flags &= ~IDE_DFLAG_USING_DMA;
  	ide_toggle_bounce(drive, 0);
  
  	drive->hwif->dma_ops->dma_host_set(drive, 0);
  }
  EXPORT_SYMBOL(ide_dma_off_quietly);
  
  /**
   *	ide_dma_off	-	disable DMA on a device
   *	@drive: drive to disable DMA on
   *
   *	Disable IDE DMA for a device on this IDE controller.
   *	Inform the user that DMA has been disabled.
   */
  
  void ide_dma_off(ide_drive_t *drive)
  {
  	printk(KERN_INFO "%s: DMA disabled
  ", drive->name);
  	ide_dma_off_quietly(drive);
  }
  EXPORT_SYMBOL(ide_dma_off);
  
  /**
   *	ide_dma_on		-	Enable DMA on a device
   *	@drive: drive to enable DMA on
   *
   *	Enable IDE DMA for a device on this IDE controller.
   */
  
  void ide_dma_on(ide_drive_t *drive)
  {
  	drive->dev_flags |= IDE_DFLAG_USING_DMA;
  	ide_toggle_bounce(drive, 1);
  
  	drive->hwif->dma_ops->dma_host_set(drive, 1);
  }
  
  int __ide_dma_bad_drive(ide_drive_t *drive)
  {
  	u16 *id = drive->id;
  
  	int blacklist = ide_in_drive_list(id, drive_blacklist);
  	if (blacklist) {
  		printk(KERN_WARNING "%s: Disabling (U)DMA for %s (blacklisted)
  ",
  				    drive->name, (char *)&id[ATA_ID_PROD]);
  		return blacklist;
  	}
  	return 0;
  }
  EXPORT_SYMBOL(__ide_dma_bad_drive);
  
  static const u8 xfer_mode_bases[] = {
  	XFER_UDMA_0,
  	XFER_MW_DMA_0,
  	XFER_SW_DMA_0,
  };
  
  static unsigned int ide_get_mode_mask(ide_drive_t *drive, u8 base, u8 req_mode)
  {
  	u16 *id = drive->id;
  	ide_hwif_t *hwif = drive->hwif;
  	const struct ide_port_ops *port_ops = hwif->port_ops;
  	unsigned int mask = 0;
  
  	switch (base) {
  	case XFER_UDMA_0:
  		if ((id[ATA_ID_FIELD_VALID] & 4) == 0)
  			break;
  		mask = id[ATA_ID_UDMA_MODES];
  		if (port_ops && port_ops->udma_filter)
  			mask &= port_ops->udma_filter(drive);
  		else
  			mask &= hwif->ultra_mask;
  
  		/*
  		 * avoid false cable warning from eighty_ninty_three()
  		 */
  		if (req_mode > XFER_UDMA_2) {
  			if ((mask & 0x78) && (eighty_ninty_three(drive) == 0))
  				mask &= 0x07;
  		}
  		break;
  	case XFER_MW_DMA_0:
  		mask = id[ATA_ID_MWDMA_MODES];
  
  		/* Also look for the CF specific MWDMA modes... */
  		if (ata_id_is_cfa(id) && (id[ATA_ID_CFA_MODES] & 0x38)) {
  			u8 mode = ((id[ATA_ID_CFA_MODES] & 0x38) >> 3) - 1;
  
  			mask |= ((2 << mode) - 1) << 3;
  		}
  
  		if (port_ops && port_ops->mdma_filter)
  			mask &= port_ops->mdma_filter(drive);
  		else
  			mask &= hwif->mwdma_mask;
  		break;
  	case XFER_SW_DMA_0:
  		mask = id[ATA_ID_SWDMA_MODES];
  		if (!(mask & ATA_SWDMA2) && (id[ATA_ID_OLD_DMA_MODES] >> 8)) {
  			u8 mode = id[ATA_ID_OLD_DMA_MODES] >> 8;
  
  			/*
  			 * if the mode is valid convert it to the mask
  			 * (the maximum allowed mode is XFER_SW_DMA_2)
  			 */
  			if (mode <= 2)
  				mask = (2 << mode) - 1;
  		}
  		mask &= hwif->swdma_mask;
  		break;
  	default:
  		BUG();
  		break;
  	}
  
  	return mask;
  }
  
  /**
   *	ide_find_dma_mode	-	compute DMA speed
   *	@drive: IDE device
   *	@req_mode: requested mode
   *
   *	Checks the drive/host capabilities and finds the speed to use for
   *	the DMA transfer.  The speed is then limited by the requested mode.
   *
   *	Returns 0 if the drive/host combination is incapable of DMA transfers
   *	or if the requested mode is not a DMA mode.
   */
  
  u8 ide_find_dma_mode(ide_drive_t *drive, u8 req_mode)
  {
  	ide_hwif_t *hwif = drive->hwif;
  	unsigned int mask;
  	int x, i;
  	u8 mode = 0;
  
  	if (drive->media != ide_disk) {
  		if (hwif->host_flags & IDE_HFLAG_NO_ATAPI_DMA)
  			return 0;
  	}
  
  	for (i = 0; i < ARRAY_SIZE(xfer_mode_bases); i++) {
  		if (req_mode < xfer_mode_bases[i])
  			continue;
  		mask = ide_get_mode_mask(drive, xfer_mode_bases[i], req_mode);
  		x = fls(mask) - 1;
  		if (x >= 0) {
  			mode = xfer_mode_bases[i] + x;
  			break;
  		}
  	}
  
  	if (hwif->chipset == ide_acorn && mode == 0) {
  		/*
  		 * is this correct?
  		 */
  		if (ide_dma_good_drive(drive) &&
  		    drive->id[ATA_ID_EIDE_DMA_TIME] < 150)
  			mode = XFER_MW_DMA_1;
  	}
  
  	mode = min(mode, req_mode);
  
  	printk(KERN_INFO "%s: %s mode selected
  ", drive->name,
  			  mode ? ide_xfer_verbose(mode) : "no DMA");
  
  	return mode;
  }
  
  static int ide_tune_dma(ide_drive_t *drive)
  {
  	ide_hwif_t *hwif = drive->hwif;
  	u8 speed;
  
  	if (ata_id_has_dma(drive->id) == 0 ||
  	    (drive->dev_flags & IDE_DFLAG_NODMA))
  		return 0;
  
  	/* consult the list of known "bad" drives */
  	if (__ide_dma_bad_drive(drive))
  		return 0;
  
  	if (hwif->host_flags & IDE_HFLAG_TRUST_BIOS_FOR_DMA)
  		return config_drive_for_dma(drive);
  
  	speed = ide_max_dma_mode(drive);
  
  	if (!speed)
  		return 0;
  
  	if (ide_set_dma_mode(drive, speed))
  		return 0;
  
  	return 1;
  }
  
  static int ide_dma_check(ide_drive_t *drive)
  {
  	ide_hwif_t *hwif = drive->hwif;
  
  	if (ide_tune_dma(drive))
  		return 0;
  
  	/* TODO: always do PIO fallback */
  	if (hwif->host_flags & IDE_HFLAG_TRUST_BIOS_FOR_DMA)
  		return -1;
  
  	ide_set_max_pio(drive);
  
  	return -1;
  }
  
  int ide_set_dma(ide_drive_t *drive)
  {
  	int rc;
  
  	/*
  	 * Force DMAing for the beginning of the check.
  	 * Some chipsets appear to do interesting
  	 * things, if not checked and cleared.
  	 *   PARANOIA!!!
  	 */
  	ide_dma_off_quietly(drive);
  
  	rc = ide_dma_check(drive);
  	if (rc)
  		return rc;
  
  	ide_dma_on(drive);
  
  	return 0;
  }
  
  void ide_check_dma_crc(ide_drive_t *drive)
  {
  	u8 mode;
  
  	ide_dma_off_quietly(drive);
  	drive->crc_count = 0;
  	mode = drive->current_speed;
  	/*
  	 * Don't try non Ultra-DMA modes without iCRC's.  Force the
  	 * device to PIO and make the user enable SWDMA/MWDMA modes.
  	 */
  	if (mode > XFER_UDMA_0 && mode <= XFER_UDMA_7)
  		mode--;
  	else
  		mode = XFER_PIO_4;
  	ide_set_xfer_rate(drive, mode);
  	if (drive->current_speed >= XFER_SW_DMA_0)
  		ide_dma_on(drive);
  }
  
  void ide_dma_lost_irq(ide_drive_t *drive)
  {
  	printk(KERN_ERR "%s: DMA interrupt recovery
  ", drive->name);
  }
  EXPORT_SYMBOL_GPL(ide_dma_lost_irq);
  
  /*
   * un-busy the port etc, and clear any pending DMA status. we want to
   * retry the current request in pio mode instead of risking tossing it
   * all away
   */
  ide_startstop_t ide_dma_timeout_retry(ide_drive_t *drive, int error)
  {
  	ide_hwif_t *hwif = drive->hwif;
  	const struct ide_dma_ops *dma_ops = hwif->dma_ops;
  	struct ide_cmd *cmd = &hwif->cmd;
  	ide_startstop_t ret = ide_stopped;
  
  	/*
  	 * end current dma transaction
  	 */
  
  	if (error < 0) {
  		printk(KERN_WARNING "%s: DMA timeout error
  ", drive->name);
  		drive->waiting_for_dma = 0;
  		(void)dma_ops->dma_end(drive);
  		ide_dma_unmap_sg(drive, cmd);
  		ret = ide_error(drive, "dma timeout error",
  				hwif->tp_ops->read_status(hwif));
  	} else {
  		printk(KERN_WARNING "%s: DMA timeout retry
  ", drive->name);
  		if (dma_ops->dma_clear)
  			dma_ops->dma_clear(drive);
  		printk(KERN_ERR "%s: timeout waiting for DMA
  ", drive->name);
  		if (dma_ops->dma_test_irq(drive) == 0) {
  			ide_dump_status(drive, "DMA timeout",
  					hwif->tp_ops->read_status(hwif));
  			drive->waiting_for_dma = 0;
  			(void)dma_ops->dma_end(drive);
  			ide_dma_unmap_sg(drive, cmd);
  		}
  	}
  
  	/*
  	 * 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->dev_flags |= IDE_DFLAG_DMA_PIO_RETRY;
  	drive->retry_pio++;
  	ide_dma_off_quietly(drive);
  
  	/*
  	 * make sure request is sane
  	 */
  	if (hwif->rq)
  		hwif->rq->errors = 0;
  	return ret;
  }
  
  void ide_release_dma_engine(ide_hwif_t *hwif)
  {
  	if (hwif->dmatable_cpu) {
  		int prd_size = hwif->prd_max_nents * hwif->prd_ent_size;
  
  		dma_free_coherent(hwif->dev, prd_size,
  				  hwif->dmatable_cpu, hwif->dmatable_dma);
  		hwif->dmatable_cpu = NULL;
  	}
  }
  EXPORT_SYMBOL_GPL(ide_release_dma_engine);
  
  int ide_allocate_dma_engine(ide_hwif_t *hwif)
  {
  	int prd_size;
  
  	if (hwif->prd_max_nents == 0)
  		hwif->prd_max_nents = PRD_ENTRIES;
  	if (hwif->prd_ent_size == 0)
  		hwif->prd_ent_size = PRD_BYTES;
  
  	prd_size = hwif->prd_max_nents * hwif->prd_ent_size;
  
  	hwif->dmatable_cpu = dma_alloc_coherent(hwif->dev, prd_size,
  						&hwif->dmatable_dma,
  						GFP_ATOMIC);
  	if (hwif->dmatable_cpu == NULL) {
  		printk(KERN_ERR "%s: unable to allocate PRD table
  ",
  			hwif->name);
  		return -ENOMEM;
  	}
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(ide_allocate_dma_engine);
  
  int ide_dma_prepare(ide_drive_t *drive, struct ide_cmd *cmd)
  {
  	const struct ide_dma_ops *dma_ops = drive->hwif->dma_ops;
  
  	if ((drive->dev_flags & IDE_DFLAG_USING_DMA) == 0 ||
  	    (dma_ops->dma_check && dma_ops->dma_check(drive, cmd)))
  		goto out;
  	ide_map_sg(drive, cmd);
  	if (ide_dma_map_sg(drive, cmd) == 0)
  		goto out_map;
  	if (dma_ops->dma_setup(drive, cmd))
  		goto out_dma_unmap;
  	drive->waiting_for_dma = 1;
  	return 0;
  out_dma_unmap:
  	ide_dma_unmap_sg(drive, cmd);
  out_map:
  	ide_map_sg(drive, cmd);
  out:
  	return 1;
  }