/*
   * pata_cs5536.c	- CS5536 PATA for new ATA layer
   *			  (C) 2007 Martin K. Petersen <mkp@mkp.net>

   *			  (C) 2011 Bartlomiej Zolnierkiewicz

   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   *
   * 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; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307	 USA
   *
   * Documentation:
   *	Available from AMD web site.
   *
   * The IDE timing registers for the CS5536 live in the Geode Machine
   * Specific Register file and not PCI config space.  Most BIOSes
   * virtualize the PCI registers so the chip looks like a standard IDE
   * controller.	Unfortunately not all implementations get this right.
   * In particular some have problems with unaligned accesses to the
   * virtualized PCI registers.  This driver always does full dword
   * writes to work around the issue.  Also, in case of a bad BIOS this
   * driver can be loaded with the "msr=1" parameter which forces using
   * the Machine Specific Registers to configure the device.
   */
  
  #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/libata.h>
  #include <scsi/scsi_host.h>

  
  #ifdef CONFIG_X86_32

  #include <asm/msr.h>

  static int use_msr;
  module_param_named(msr, use_msr, int, 0644);
  MODULE_PARM_DESC(msr, "Force using MSR to configure IDE function (Default: 0)");
  #else

  #undef rdmsr	/* avoid accidental MSR usage on, e.g. x86-64 */
  #undef wrmsr

  #define rdmsr(x, y, z) do { } while (0)
  #define wrmsr(x, y, z) do { } while (0)
  #define use_msr 0
  #endif

  
  #define DRV_NAME	"pata_cs5536"

  #define DRV_VERSION	"0.0.8"

  
  enum {

  	MSR_IDE_CFG		= 0x51300010,

  	PCI_IDE_CFG		= 0x40,

  	CFG			= 0,
  	DTC			= 2,
  	CAST			= 3,
  	ETC			= 4,
  
  	IDE_CFG_CHANEN		= (1 << 1),
  	IDE_CFG_CABLE		= (1 << 17) | (1 << 16),

  
  	IDE_D0_SHIFT		= 24,
  	IDE_D1_SHIFT		= 16,
  	IDE_DRV_MASK		= 0xff,
  
  	IDE_CAST_D0_SHIFT	= 6,
  	IDE_CAST_D1_SHIFT	= 4,
  	IDE_CAST_DRV_MASK	= 0x3,
  	IDE_CAST_CMD_MASK	= 0xff,
  	IDE_CAST_CMD_SHIFT	= 24,

  	IDE_ETC_UDMA_MASK	= 0xc0,

  };

  static int cs5536_read(struct pci_dev *pdev, int reg, u32 *val)

  {
  	if (unlikely(use_msr)) {

  		u32 dummy __maybe_unused;

  		rdmsr(MSR_IDE_CFG + reg, *val, dummy);

  		return 0;
  	}

  	return pci_read_config_dword(pdev, PCI_IDE_CFG + reg * 4, val);

  }

  static int cs5536_write(struct pci_dev *pdev, int reg, int val)

  {
  	if (unlikely(use_msr)) {

  		wrmsr(MSR_IDE_CFG + reg, val, 0);

  		return 0;
  	}

  	return pci_write_config_dword(pdev, PCI_IDE_CFG + reg * 4, val);
  }
  
  static void cs5536_program_dtc(struct ata_device *adev, u8 tim)
  {
  	struct pci_dev *pdev = to_pci_dev(adev->link->ap->host->dev);
  	int dshift = adev->devno ? IDE_D1_SHIFT : IDE_D0_SHIFT;
  	u32 dtc;
  
  	cs5536_read(pdev, DTC, &dtc);
  	dtc &= ~(IDE_DRV_MASK << dshift);
  	dtc |= tim << dshift;
  	cs5536_write(pdev, DTC, dtc);

  }
  
  /**
   *	cs5536_cable_detect	-	detect cable type
   *	@ap: Port to detect on

   *

   *	Perform cable detection for ATA66 capable cable.
   *
   *	Returns a cable type.

   */
  
  static int cs5536_cable_detect(struct ata_port *ap)
  {
  	struct pci_dev *pdev = to_pci_dev(ap->host->dev);
  	u32 cfg;
  
  	cs5536_read(pdev, CFG, &cfg);

  	if (cfg & IDE_CFG_CABLE)

  		return ATA_CBL_PATA80;
  	else
  		return ATA_CBL_PATA40;
  }
  
  /**
   *	cs5536_set_piomode		-	PIO setup
   *	@ap: ATA interface
   *	@adev: device on the interface
   */
  
  static void cs5536_set_piomode(struct ata_port *ap, struct ata_device *adev)
  {
  	static const u8 drv_timings[5] = {
  		0x98, 0x55, 0x32, 0x21, 0x20,
  	};
  
  	static const u8 addr_timings[5] = {
  		0x2, 0x1, 0x0, 0x0, 0x0,
  	};
  
  	static const u8 cmd_timings[5] = {
  		0x99, 0x92, 0x90, 0x22, 0x20,
  	};
  
  	struct pci_dev *pdev = to_pci_dev(ap->host->dev);
  	struct ata_device *pair = ata_dev_pair(adev);
  	int mode = adev->pio_mode - XFER_PIO_0;
  	int cmdmode = mode;

  	int cshift = adev->devno ? IDE_CAST_D1_SHIFT : IDE_CAST_D0_SHIFT;

  	u32 cast;

  
  	if (pair)
  		cmdmode = min(mode, pair->pio_mode - XFER_PIO_0);

  	cs5536_program_dtc(adev, drv_timings[mode]);

  	cs5536_read(pdev, CAST, &cast);

  
  	cast &= ~(IDE_CAST_DRV_MASK << cshift);
  	cast |= addr_timings[mode] << cshift;
  
  	cast &= ~(IDE_CAST_CMD_MASK << IDE_CAST_CMD_SHIFT);
  	cast |= cmd_timings[cmdmode] << IDE_CAST_CMD_SHIFT;

  	cs5536_write(pdev, CAST, cast);

  }
  
  /**
   *	cs5536_set_dmamode		-	DMA timing setup
   *	@ap: ATA interface
   *	@adev: Device being configured
   *
   */
  
  static void cs5536_set_dmamode(struct ata_port *ap, struct ata_device *adev)
  {
  	static const u8 udma_timings[6] = {
  		0xc2, 0xc1, 0xc0, 0xc4, 0xc5, 0xc6,
  	};
  
  	static const u8 mwdma_timings[3] = {
  		0x67, 0x21, 0x20,
  	};
  
  	struct pci_dev *pdev = to_pci_dev(ap->host->dev);

  	u32 etc;

  	int mode = adev->dma_mode;

  	int dshift = adev->devno ? IDE_D1_SHIFT : IDE_D0_SHIFT;

  	cs5536_read(pdev, ETC, &etc);

  	if (mode >= XFER_UDMA_0) {

  		etc &= ~(IDE_DRV_MASK << dshift);
  		etc |= udma_timings[mode - XFER_UDMA_0] << dshift;

  	} else { /* MWDMA */

  		etc &= ~(IDE_ETC_UDMA_MASK << dshift);
  		cs5536_program_dtc(adev, mwdma_timings[mode - XFER_MW_DMA_0]);

  	}

  
  	cs5536_write(pdev, ETC, etc);

  }
  
  static struct scsi_host_template cs5536_sht = {

  	ATA_BMDMA_SHT(DRV_NAME),

  };
  
  static struct ata_port_operations cs5536_port_ops = {

  	.inherits		= &ata_bmdma32_port_ops,

  	.cable_detect		= cs5536_cable_detect,

  	.set_piomode		= cs5536_set_piomode,
  	.set_dmamode		= cs5536_set_dmamode,

  };
  
  /**
   *	cs5536_init_one
   *	@dev: PCI device
   *	@id: Entry in match table
   *
   */
  
  static int cs5536_init_one(struct pci_dev *dev, const struct pci_device_id *id)
  {
  	static const struct ata_port_info info = {

  		.flags = ATA_FLAG_SLAVE_POSS,

  		.pio_mask = ATA_PIO4,
  		.mwdma_mask = ATA_MWDMA2,

  		.udma_mask = ATA_UDMA5,
  		.port_ops = &cs5536_port_ops,
  	};
  
  	const struct ata_port_info *ppi[] = { &info, &ata_dummy_port_info };
  	u32 cfg;
  
  	if (use_msr)
  		printk(KERN_ERR DRV_NAME ": Using MSR regs instead of PCI
  ");
  
  	cs5536_read(dev, CFG, &cfg);
  
  	if ((cfg & IDE_CFG_CHANEN) == 0) {
  		printk(KERN_ERR DRV_NAME ": disabled by BIOS
  ");
  		return -ENODEV;
  	}

  	return ata_pci_bmdma_init_one(dev, ppi, &cs5536_sht, NULL, 0);

  }
  
  static const struct pci_device_id cs5536[] = {
  	{ PCI_VDEVICE(AMD,	PCI_DEVICE_ID_AMD_CS5536_IDE), },
  	{ },
  };
  
  static struct pci_driver cs5536_pci_driver = {
  	.name		= DRV_NAME,
  	.id_table	= cs5536,
  	.probe		= cs5536_init_one,
  	.remove		= ata_pci_remove_one,
  #ifdef CONFIG_PM
  	.suspend	= ata_pci_device_suspend,
  	.resume		= ata_pci_device_resume,
  #endif
  };
  
  static int __init cs5536_init(void)
  {
  	return pci_register_driver(&cs5536_pci_driver);
  }
  
  static void __exit cs5536_exit(void)
  {
  	pci_unregister_driver(&cs5536_pci_driver);
  }
  
  MODULE_AUTHOR("Martin K. Petersen");
  MODULE_DESCRIPTION("low-level driver for the CS5536 IDE controller");
  MODULE_LICENSE("GPL");
  MODULE_DEVICE_TABLE(pci, cs5536);
  MODULE_VERSION(DRV_VERSION);

  
  module_init(cs5536_init);
  module_exit(cs5536_exit);