/*
 *    pata_ns87415.c - NS87415 (non PARISC) PATA
 *
 *	(C) 2005 Red Hat <alan@redhat.com>
 *
 *    This is a fairly generic MWDMA controller. It has some limitations
 *    as it requires timing reloads on PIO/DMA transitions but it is otherwise
 *    fairly well designed.
 *
 *    This driver assumes the firmware has left the chip in a valid ST506
 *    compliant state, either legacy IRQ 14/15 or native INTA shared. You
 *    may need to add platform code if your system fails to do this.
 *
 *    The same cell appears in the 87560 controller used by some PARISC
 *    systems. This has its own special mountain of errata.
 *
 *    TODO:
 *	Test PARISC SuperIO
 *	Get someone to test on SPARC
 *	Implement lazy pio/dma switching for better performance
 *	8bit shared timing.
 *	See if we need to kill the FIFO for ATAPI
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/init.h>
#include <linux/blkdev.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <scsi/scsi_host.h>
#include <linux/libata.h>
#include <linux/ata.h>

#define DRV_NAME	"pata_ns87415"
#define DRV_VERSION	"0.0.1"

/**
 *	ns87415_set_mode - Initialize host controller mode timings
 *	@ap: Port whose timings we are configuring
 *	@adev: Device whose timings we are configuring
 *	@mode: Mode to set
 *
 *	Program the mode registers for this controller, channel and
 *	device. Because the chip is quite an old design we have to do this
 *	for PIO/DMA switches.
 *
 *	LOCKING:
 *	None (inherited from caller).
 */

static void ns87415_set_mode(struct ata_port *ap, struct ata_device *adev, u8 mode)
{
	struct pci_dev *dev	= to_pci_dev(ap->host->dev);
	int unit		= 2 * ap->port_no + adev->devno;
	int timing		= 0x44 + 2 * unit;
	unsigned long T		= 1000000000 / 33333;	/* PCI clocks */
	struct ata_timing t;
	u16 clocking;
	u8 iordy;
	u8 status;

	/* Timing register format is 17 - low nybble read timing with
	   the high nybble being 16 - x for recovery time in PCI clocks */

	ata_timing_compute(adev, adev->pio_mode, &t, T, 0);

	clocking = 17 - clamp_val(t.active, 2, 17);
	clocking |= (16 - clamp_val(t.recover, 1, 16)) << 4;
 	/* Use the same timing for read and write bytes */
	clocking |= (clocking << 8);
	pci_write_config_word(dev, timing, clocking);

	/* Set the IORDY enable versus DMA enable on or off properly */
	pci_read_config_byte(dev, 0x42, &iordy);
	iordy &= ~(1 << (4 + unit));
	if (mode >= XFER_MW_DMA_0 || !ata_pio_need_iordy(adev))
		iordy |= (1 << (4 + unit));

	/* Paranoia: We shouldn't ever get here with busy write buffers
	   but if so wait */

	pci_read_config_byte(dev, 0x43, &status);
	while (status & 0x03) {
		udelay(1);
		pci_read_config_byte(dev, 0x43, &status);
	}
	/* Flip the IORDY/DMA bits now we are sure the write buffers are
	   clear */
	pci_write_config_byte(dev, 0x42, iordy);

	/* TODO: Set byte 54 command timing to the best 8bit
	   mode shared by all four devices */
}

/**
 *	ns87415_set_piomode - Initialize host controller PATA PIO timings
 *	@ap: Port whose timings we are configuring
 *	@adev: Device to program
 *
 *	Set PIO mode for device, in host controller PCI config space.
 *
 *	LOCKING:
 *	None (inherited from caller).
 */

static void ns87415_set_piomode(struct ata_port *ap, struct ata_device *adev)
{
	ns87415_set_mode(ap, adev, adev->pio_mode);
}

/**
 *	ns87415_bmdma_setup		-	Set up DMA
 *	@qc: Command block
 *
 *	Set up for bus masterng DMA. We have to do this ourselves
 *	rather than use the helper due to a chip erratum
 */

static void ns87415_bmdma_setup(struct ata_queued_cmd *qc)
{
	struct ata_port *ap = qc->ap;
	unsigned int rw = (qc->tf.flags & ATA_TFLAG_WRITE);
	u8 dmactl;

	/* load PRD table addr. */
	mb();	/* make sure PRD table writes are visible to controller */
	iowrite32(ap->prd_dma, ap->ioaddr.bmdma_addr + ATA_DMA_TABLE_OFS);

	/* specify data direction, triple-check start bit is clear */
	dmactl = ioread8(ap->ioaddr.bmdma_addr + ATA_DMA_CMD);
	dmactl &= ~(ATA_DMA_WR | ATA_DMA_START);
	/* Due to an erratum we need to write these bits to the wrong
	   place - which does save us an I/O bizarrely */
	dmactl |= ATA_DMA_INTR | ATA_DMA_ERR;
	if (!rw)
		dmactl |= ATA_DMA_WR;
	iowrite8(dmactl, ap->ioaddr.bmdma_addr + ATA_DMA_CMD);
	/* issue r/w command */
	ap->ops->sff_exec_command(ap, &qc->tf);
}

/**
 *	ns87415_bmdma_start		-	Begin DMA transfer
 *	@qc: Command block
 *
 *	Switch the timings for the chip and set up for a DMA transfer
 *	before the DMA burst begins.
 *
 *	FIXME: We should do lazy switching on bmdma_start versus
 *	ata_pio_data_xfer for better performance.
 */

static void ns87415_bmdma_start(struct ata_queued_cmd *qc)
{
	ns87415_set_mode(qc->ap, qc->dev, qc->dev->dma_mode);
	ata_bmdma_start(qc);
}

/**
 *	ns87415_bmdma_stop		-	End DMA transfer
 *	@qc: Command block
 *
 *	End DMA mode and switch the controller back into PIO mode
 */

static void ns87415_bmdma_stop(struct ata_queued_cmd *qc)
{
	ata_bmdma_stop(qc);
	ns87415_set_mode(qc->ap, qc->dev, qc->dev->pio_mode);
}

/**
 *	ns87415_irq_clear		-	Clear interrupt
 *	@ap: Channel to clear
 *
 *	Erratum: Due to a chip bug regisers 02 and 0A bit 1 and 2 (the
 *	error bits) are reset by writing to register 00 or 08.
 */

static void ns87415_irq_clear(struct ata_port *ap)
{
	void __iomem *mmio = ap->ioaddr.bmdma_addr;

	if (!mmio)
		return;
	iowrite8((ioread8(mmio + ATA_DMA_CMD) | ATA_DMA_INTR | ATA_DMA_ERR),
			mmio + ATA_DMA_CMD);
}

/**
 *	ns87415_check_atapi_dma		-	ATAPI DMA filter
 *	@qc: Command block
 *
 *	Disable ATAPI DMA (for now). We may be able to do DMA if we
 *	kill the prefetching. This isn't clear.
 */

static int ns87415_check_atapi_dma(struct ata_queued_cmd *qc)
{
	return -EOPNOTSUPP;
}

#if defined(CONFIG_SUPERIO)

/* SUPERIO 87560 is a PoS chip that NatSem denies exists.
 * Unfortunately, it's built-in on all Astro-based PA-RISC workstations
 * which use the integrated NS87514 cell for CD-ROM support.
 * i.e we have to support for CD-ROM installs.
 * See drivers/parisc/superio.c for more gory details.
 *
 * Workarounds taken from drivers/ide/pci/ns87415.c
 */

#include <asm/superio.h>

#define SUPERIO_IDE_MAX_RETRIES 25

/**
 *	ns87560_read_buggy	-	workaround buggy Super I/O chip
 *	@port: Port to read
 *
 *	Work around chipset problems in the 87560 SuperIO chip
 */

static u8 ns87560_read_buggy(void __iomem *port)
{
	u8 tmp;
	int retries = SUPERIO_IDE_MAX_RETRIES;
	do {
		tmp = ioread8(port);
		if (tmp != 0)
			return tmp;
		udelay(50);
	} while(retries-- > 0);
	return tmp;
}

/**
 *	ns87560_check_status
 *	@ap: channel to check
 *
 *	Return the status of the channel working around the
 *	87560 flaws.
 */

static u8 ns87560_check_status(struct ata_port *ap)
{
	return ns87560_read_buggy(ap->ioaddr.status_addr);
}

/**
 *	ns87560_tf_read - input device's ATA taskfile shadow registers
 *	@ap: Port from which input is read
 *	@tf: ATA taskfile register set for storing input
 *
 *	Reads ATA taskfile registers for currently-selected device
 *	into @tf. Work around the 87560 bugs.
 *
 *	LOCKING:
 *	Inherited from caller.
 */
void ns87560_tf_read(struct ata_port *ap, struct ata_taskfile *tf)
{
	struct ata_ioports *ioaddr = &ap->ioaddr;

	tf->command = ns87560_check_status(ap);
	tf->feature = ioread8(ioaddr->error_addr);
	tf->nsect = ioread8(ioaddr->nsect_addr);
	tf->lbal = ioread8(ioaddr->lbal_addr);
	tf->lbam = ioread8(ioaddr->lbam_addr);
	tf->lbah = ioread8(ioaddr->lbah_addr);
	tf->device = ns87560_read_buggy(ioaddr->device_addr);

	if (tf->flags & ATA_TFLAG_LBA48) {
		iowrite8(tf->ctl | ATA_HOB, ioaddr->ctl_addr);
		tf->hob_feature = ioread8(ioaddr->error_addr);
		tf->hob_nsect = ioread8(ioaddr->nsect_addr);
		tf->hob_lbal = ioread8(ioaddr->lbal_addr);
		tf->hob_lbam = ioread8(ioaddr->lbam_addr);
		tf->hob_lbah = ioread8(ioaddr->lbah_addr);
		iowrite8(tf->ctl, ioaddr->ctl_addr);
		ap->last_ctl = tf->ctl;
	}
}

/**
 *	ns87560_bmdma_status
 *	@ap: channel to check
 *
 *	Return the DMA status of the channel working around the
 *	87560 flaws.
 */

static u8 ns87560_bmdma_status(struct ata_port *ap)
{
	return ns87560_read_buggy(ap->ioaddr.bmdma_addr + ATA_DMA_STATUS);
}
#endif		/* 87560 SuperIO Support */

static struct ata_port_operations ns87415_pata_ops = {
	.inherits		= &ata_bmdma_port_ops,

	.check_atapi_dma	= ns87415_check_atapi_dma,
	.bmdma_setup		= ns87415_bmdma_setup,
	.bmdma_start		= ns87415_bmdma_start,
	.bmdma_stop		= ns87415_bmdma_stop,
	.sff_irq_clear		= ns87415_irq_clear,

	.cable_detect		= ata_cable_40wire,
	.set_piomode		= ns87415_set_piomode,
};

#if defined(CONFIG_SUPERIO)
static struct ata_port_operations ns87560_pata_ops = {
	.inherits		= &ns87415_pata_ops,
	.sff_tf_read		= ns87560_tf_read,
	.sff_check_status	= ns87560_check_status,
	.bmdma_status		= ns87560_bmdma_status,
};
#endif

static struct scsi_host_template ns87415_sht = {
	ATA_BMDMA_SHT(DRV_NAME),
};


/**
 *	ns87415_init_one - Register 87415 ATA PCI device with kernel services
 *	@pdev: PCI device to register
 *	@ent: Entry in ns87415_pci_tbl matching with @pdev
 *
 *	Called from kernel PCI layer.  We probe for combined mode (sigh),
 *	and then hand over control to libata, for it to do the rest.
 *
 *	LOCKING:
 *	Inherited from PCI layer (may sleep).
 *
 *	RETURNS:
 *	Zero on success, or -ERRNO value.
 */

static int ns87415_init_one (struct pci_dev *pdev, const struct pci_device_id *ent)
{
	static int printed_version;
	static const struct ata_port_info info = {
		.flags		= ATA_FLAG_SLAVE_POSS,
		.pio_mask	= 0x1f,	/* pio0-4 */
		.mwdma_mask	= 0x07, /* mwdma0-2 */
		.port_ops	= &ns87415_pata_ops,
	};
	const struct ata_port_info *ppi[] = { &info, NULL };
	int rc;
#if defined(CONFIG_SUPERIO)
	static const struct ata_port_info info87560 = {
		.flags		= ATA_FLAG_SLAVE_POSS,
		.pio_mask	= 0x1f,	/* pio0-4 */
		.mwdma_mask	= 0x07, /* mwdma0-2 */
		.port_ops	= &ns87560_pata_ops,
	};

	if (PCI_SLOT(pdev->devfn) == 0x0E)
		ppi[0] = &info87560;
#endif
	if (!printed_version++)
		dev_printk(KERN_DEBUG, &pdev->dev,
			   "version " DRV_VERSION "\n");

	rc = pcim_enable_device(pdev);
	if (rc)
		return rc;

	/* Select 512 byte sectors */
	pci_write_config_byte(pdev, 0x55, 0xEE);
	/* Select PIO0 8bit clocking */
	pci_write_config_byte(pdev, 0x54, 0xB7);
	return ata_pci_sff_init_one(pdev, ppi, &ns87415_sht, NULL);
}

static const struct pci_device_id ns87415_pci_tbl[] = {
	{ PCI_VDEVICE(NS, PCI_DEVICE_ID_NS_87415), },

	{ }	/* terminate list */
};

static struct pci_driver ns87415_pci_driver = {
	.name			= DRV_NAME,
	.id_table		= ns87415_pci_tbl,
	.probe			= ns87415_init_one,
	.remove			= ata_pci_remove_one,
#ifdef CONFIG_PM
	.suspend		= ata_pci_device_suspend,
	.resume			= ata_pci_device_resume,
#endif
};

static int __init ns87415_init(void)
{
	return pci_register_driver(&ns87415_pci_driver);
}

static void __exit ns87415_exit(void)
{
	pci_unregister_driver(&ns87415_pci_driver);
}

module_init(ns87415_init);
module_exit(ns87415_exit);

MODULE_AUTHOR("Alan Cox");
MODULE_DESCRIPTION("ATA low-level driver for NS87415 controllers");
MODULE_LICENSE("GPL");
MODULE_DEVICE_TABLE(pci, ns87415_pci_tbl);
MODULE_VERSION(DRV_VERSION);
