text: // SPDX-License-Identifier: GPL-2.0-only
  #include <linux/types.h>
  #include <linux/kernel.h>
  #include <linux/export.h>
  #include <linux/ide.h>
  #include <linux/scatterlist.h>
  #include <linux/dma-mapping.h>
  #include <linux/io.h>
  
  /**
   *	config_drive_for_dma	-	attempt to activate IDE DMA
   *	@drive: the drive to place in DMA mode
   *
   *	If the drive supports at least mode 2 DMA or UDMA of any kind
   *	then attempt to place it into DMA mode. Drives that are known to
   *	support DMA but predate the DMA properties or that are known
   *	to have DMA handling bugs are also set up appropriately based
   *	on the good/bad drive lists.
   */
  
  int config_drive_for_dma(ide_drive_t *drive)
  {
  	ide_hwif_t *hwif = drive->hwif;
  	u16 *id = drive->id;
  
  	if (drive->media != ide_disk) {
  		if (hwif->host_flags & IDE_HFLAG_NO_ATAPI_DMA)
  			return 0;
  	}
  
  	/*
  	 * Enable DMA on any drive that has
  	 * UltraDMA (mode 0/1/2/3/4/5/6) enabled
  	 */
  	if ((id[ATA_ID_FIELD_VALID] & 4) &&
  	    ((id[ATA_ID_UDMA_MODES] >> 8) & 0x7f))
  		return 1;
  
  	/*
  	 * Enable DMA on any drive that has mode2 DMA
  	 * (multi or single) enabled
  	 */
  	if ((id[ATA_ID_MWDMA_MODES] & 0x404) == 0x404 ||
  	    (id[ATA_ID_SWDMA_MODES] & 0x404) == 0x404)
  		return 1;
  
  	/* Consult the list of known "good" drives */
  	if (ide_dma_good_drive(drive))
  		return 1;
  
  	return 0;
  }
  
  u8 ide_dma_sff_read_status(ide_hwif_t *hwif)
  {
  	unsigned long addr = hwif->dma_base + ATA_DMA_STATUS;
  
  	if (hwif->host_flags & IDE_HFLAG_MMIO)
  		return readb((void __iomem *)addr);
  	else
  		return inb(addr);
  }
  EXPORT_SYMBOL_GPL(ide_dma_sff_read_status);
  
  static void ide_dma_sff_write_status(ide_hwif_t *hwif, u8 val)
  {
  	unsigned long addr = hwif->dma_base + ATA_DMA_STATUS;
  
  	if (hwif->host_flags & IDE_HFLAG_MMIO)
  		writeb(val, (void __iomem *)addr);
  	else
  		outb(val, addr);
  }
  
  /**
   *	ide_dma_host_set	-	Enable/disable DMA on a host
   *	@drive: drive to control
   *
   *	Enable/disable DMA on an IDE controller following generic
   *	bus-mastering IDE controller behaviour.
   */
  
  void ide_dma_host_set(ide_drive_t *drive, int on)
  {
  	ide_hwif_t *hwif = drive->hwif;
  	u8 unit = drive->dn & 1;
  	u8 dma_stat = hwif->dma_ops->dma_sff_read_status(hwif);
  
  	if (on)
  		dma_stat |= (1 << (5 + unit));
  	else
  		dma_stat &= ~(1 << (5 + unit));
  
  	ide_dma_sff_write_status(hwif, dma_stat);
  }
  EXPORT_SYMBOL_GPL(ide_dma_host_set);
  
  /**
   *	ide_build_dmatable	-	build IDE DMA table
   *
   *	ide_build_dmatable() prepares a dma request. We map the command
   *	to get the pci bus addresses of the buffers and then build up
   *	the PRD table that the IDE layer wants to be fed.
   *
   *	Most chipsets correctly interpret a length of 0x0000 as 64KB,
   *	but at least one (e.g. CS5530) misinterprets it as zero (!).
   *	So we break the 64KB entry into two 32KB entries instead.
   *
   *	Returns the number of built PRD entries if all went okay,
   *	returns 0 otherwise.
   *
   *	May also be invoked from trm290.c
   */
  
  int ide_build_dmatable(ide_drive_t *drive, struct ide_cmd *cmd)
  {
  	ide_hwif_t *hwif = drive->hwif;
  	__le32 *table = (__le32 *)hwif->dmatable_cpu;
  	unsigned int count = 0;
  	int i;
  	struct scatterlist *sg;
  	u8 is_trm290 = !!(hwif->host_flags & IDE_HFLAG_TRM290);
  
  	for_each_sg(hwif->sg_table, sg, cmd->sg_nents, i) {
  		u32 cur_addr, cur_len, xcount, bcount;
  
  		cur_addr = sg_dma_address(sg);
  		cur_len = sg_dma_len(sg);
  
  		/*
  		 * Fill in the dma table, without crossing any 64kB boundaries.
  		 * Most hardware requires 16-bit alignment of all blocks,
  		 * but the trm290 requires 32-bit alignment.
  		 */
  
  		while (cur_len) {
  			if (count++ >= PRD_ENTRIES)
  				goto use_pio_instead;
  
  			bcount = 0x10000 - (cur_addr & 0xffff);
  			if (bcount > cur_len)
  				bcount = cur_len;
  			*table++ = cpu_to_le32(cur_addr);
  			xcount = bcount & 0xffff;
  			if (is_trm290)
  				xcount = ((xcount >> 2) - 1) << 16;
  			else if (xcount == 0x0000) {
  				if (count++ >= PRD_ENTRIES)
  					goto use_pio_instead;
  				*table++ = cpu_to_le32(0x8000);
  				*table++ = cpu_to_le32(cur_addr + 0x8000);
  				xcount = 0x8000;
  			}
  			*table++ = cpu_to_le32(xcount);
  			cur_addr += bcount;
  			cur_len -= bcount;
  		}
  	}
  
  	if (count) {
  		if (!is_trm290)
  			*--table |= cpu_to_le32(0x80000000);
  		return count;
  	}
  
  use_pio_instead:
  	printk(KERN_ERR "%s: %s\n", drive->name,
  		count ? "DMA table too small" : "empty DMA table?");
  
  	return 0; /* revert to PIO for this request */
  }
  EXPORT_SYMBOL_GPL(ide_build_dmatable);
  
  /**
   *	ide_dma_setup	-	begin a DMA phase
   *	@drive: target device
   *	@cmd: command
   *
   *	Build an IDE DMA PRD (IDE speak for scatter gather table)
   *	and then set up the DMA transfer registers for a device
   *	that follows generic IDE PCI DMA behaviour. Controllers can
   *	override this function if they need to
   *
   *	Returns 0 on success. If a PIO fallback is required then 1
   *	is returned.
   */
  
  int ide_dma_setup(ide_drive_t *drive, struct ide_cmd *cmd)
  {
  	ide_hwif_t *hwif = drive->hwif;
  	u8 mmio = (hwif->host_flags & IDE_HFLAG_MMIO) ? 1 : 0;
  	u8 rw = (cmd->tf_flags & IDE_TFLAG_WRITE) ? 0 : ATA_DMA_WR;
  	u8 dma_stat;
  
  	/* fall back to pio! */
  	if (ide_build_dmatable(drive, cmd) == 0) {
  		ide_map_sg(drive, cmd);
  		return 1;
  	}
  
  	/* PRD table */
  	if (mmio)
  		writel(hwif->dmatable_dma,
  		       (void __iomem *)(hwif->dma_base + ATA_DMA_TABLE_OFS));
  	else
  		outl(hwif->dmatable_dma, hwif->dma_base + ATA_DMA_TABLE_OFS);
  
  	/* specify r/w */
  	if (mmio)
  		writeb(rw, (void __iomem *)(hwif->dma_base + ATA_DMA_CMD));
  	else
  		outb(rw, hwif->dma_base + ATA_DMA_CMD);
  
  	/* read DMA status for INTR & ERROR flags */
  	dma_stat = hwif->dma_ops->dma_sff_read_status(hwif);
  
  	/* clear INTR & ERROR flags */
  	ide_dma_sff_write_status(hwif, dma_stat | ATA_DMA_ERR | ATA_DMA_INTR);
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(ide_dma_setup);
  
  /**
   *	ide_dma_sff_timer_expiry	-	handle a DMA timeout
   *	@drive: Drive that timed out
   *
   *	An IDE DMA transfer timed out. In the event of an error we ask
   *	the driver to resolve the problem, if a DMA transfer is still
   *	in progress we continue to wait (arguably we need to add a
   *	secondary 'I don't care what the drive thinks' timeout here)
   *	Finally if we have an interrupt we let it complete the I/O.
   *	But only one time - we clear expiry and if it's still not
   *	completed after WAIT_CMD, we error and retry in PIO.
   *	This can occur if an interrupt is lost or due to hang or bugs.
   */
  
  int ide_dma_sff_timer_expiry(ide_drive_t *drive)
  {
  	ide_hwif_t *hwif = drive->hwif;
  	u8 dma_stat = hwif->dma_ops->dma_sff_read_status(hwif);
  
  	printk(KERN_WARNING "%s: %s: DMA status (0x%02x)\n",
  		drive->name, __func__, dma_stat);
  
  	if ((dma_stat & 0x18) == 0x18)	/* BUSY Stupid Early Timer !! */
  		return WAIT_CMD;
  
  	hwif->expiry = NULL;	/* one free ride for now */
  
  	if (dma_stat & ATA_DMA_ERR)	/* ERROR */
  		return -1;
  
  	if (dma_stat & ATA_DMA_ACTIVE)	/* DMAing */
  		return WAIT_CMD;
  
  	if (dma_stat & ATA_DMA_INTR)	/* Got an Interrupt */
  		return WAIT_CMD;
  
  	return 0;	/* Status is unknown -- reset the bus */
  }
  EXPORT_SYMBOL_GPL(ide_dma_sff_timer_expiry);
  
  void ide_dma_start(ide_drive_t *drive)
  {
  	ide_hwif_t *hwif = drive->hwif;
  	u8 dma_cmd;
  
  	/* Note that this is done *after* the cmd has
  	 * been issued to the drive, as per the BM-IDE spec.
  	 * The Promise Ultra33 doesn't work correctly when
  	 * we do this part before issuing the drive cmd.
  	 */
  	if (hwif->host_flags & IDE_HFLAG_MMIO) {
  		dma_cmd = readb((void __iomem *)(hwif->dma_base + ATA_DMA_CMD));
  		writeb(dma_cmd | ATA_DMA_START,
  		       (void __iomem *)(hwif->dma_base + ATA_DMA_CMD));
  	} else {
  		dma_cmd = inb(hwif->dma_base + ATA_DMA_CMD);
  		outb(dma_cmd | ATA_DMA_START, hwif->dma_base + ATA_DMA_CMD);
  	}
  }
  EXPORT_SYMBOL_GPL(ide_dma_start);
  
  /* returns 1 on error, 0 otherwise */
  int ide_dma_end(ide_drive_t *drive)
  {
  	ide_hwif_t *hwif = drive->hwif;
  	u8 dma_stat = 0, dma_cmd = 0;
  
  	/* stop DMA */
  	if (hwif->host_flags & IDE_HFLAG_MMIO) {
  		dma_cmd = readb((void __iomem *)(hwif->dma_base + ATA_DMA_CMD));
  		writeb(dma_cmd & ~ATA_DMA_START,
  		       (void __iomem *)(hwif->dma_base + ATA_DMA_CMD));
  	} else {
  		dma_cmd = inb(hwif->dma_base + ATA_DMA_CMD);
  		outb(dma_cmd & ~ATA_DMA_START, hwif->dma_base + ATA_DMA_CMD);
  	}
  
  	/* get DMA status */
  	dma_stat = hwif->dma_ops->dma_sff_read_status(hwif);
  
  	/* clear INTR & ERROR bits */
  	ide_dma_sff_write_status(hwif, dma_stat | ATA_DMA_ERR | ATA_DMA_INTR);
  
  #define CHECK_DMA_MASK (ATA_DMA_ACTIVE | ATA_DMA_ERR | ATA_DMA_INTR)
  
  	/* verify good DMA status */
  	if ((dma_stat & CHECK_DMA_MASK) != ATA_DMA_INTR)
  		return 0x10 | dma_stat;
  	return 0;
  }
  EXPORT_SYMBOL_GPL(ide_dma_end);
  
  /* returns 1 if dma irq issued, 0 otherwise */
  int ide_dma_test_irq(ide_drive_t *drive)
  {
  	ide_hwif_t *hwif = drive->hwif;
  	u8 dma_stat = hwif->dma_ops->dma_sff_read_status(hwif);
  
  	return (dma_stat & ATA_DMA_INTR) ? 1 : 0;
  }
  EXPORT_SYMBOL_GPL(ide_dma_test_irq);
  
  const struct ide_dma_ops sff_dma_ops = {
  	.dma_host_set		= ide_dma_host_set,
  	.dma_setup		= ide_dma_setup,
  	.dma_start		= ide_dma_start,
  	.dma_end		= ide_dma_end,
  	.dma_test_irq		= ide_dma_test_irq,
  	.dma_lost_irq		= ide_dma_lost_irq,
  	.dma_timer_expiry	= ide_dma_sff_timer_expiry,
  	.dma_sff_read_status	= ide_dma_sff_read_status,
  };
  EXPORT_SYMBOL_GPL(sff_dma_ops);
  