/*
   * CS5536 PATA support
   * (C) 2007 Martin K. Petersen <mkp@mkp.net>
   * (C) 2009 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/ide.h>
  #include <asm/msr.h>
  
  #define DRV_NAME	"cs5536"
  
  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_SHIFT	= 24,
  	IDE_CAST_CMD_MASK	= 0xff,
  
  	IDE_ETC_UDMA_MASK	= 0xc0,
  };
  
  static int use_msr;
  
  static int cs5536_read(struct pci_dev *pdev, int reg, u32 *val)
  {
  	if (unlikely(use_msr)) {
  		u32 dummy;
  
  		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(ide_drive_t *drive, u8 tim)
  {
  	struct pci_dev *pdev = to_pci_dev(drive->hwif->dev);
  	int dshift = (drive->dn & 1) ? 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
   *	@hwif: Port to detect on
   *
   *	Perform cable detection for ATA66 capable cable.
   *
   *	Returns a cable type.
   */
  
  static u8 cs5536_cable_detect(ide_hwif_t *hwif)
  {
  	struct pci_dev *pdev = to_pci_dev(hwif->dev);
  	u32 cfg;
  
  	cs5536_read(pdev, CFG, &cfg);
  
  	if (cfg & IDE_CFG_CABLE)
  		return ATA_CBL_PATA80;
  	else
  		return ATA_CBL_PATA40;
  }
  
  /**
   *	cs5536_set_pio_mode		-	PIO timing setup
   *	@hwif: ATA port
   *	@drive: ATA device
   */
  
  static void cs5536_set_pio_mode(ide_hwif_t *hwif, ide_drive_t *drive)
  {
  	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(hwif->dev);
  	ide_drive_t *pair = ide_get_pair_dev(drive);
  	int cshift = (drive->dn & 1) ? IDE_CAST_D1_SHIFT : IDE_CAST_D0_SHIFT;
  	unsigned long timings = (unsigned long)ide_get_drivedata(drive);
  	u32 cast;
  	const u8 pio = drive->pio_mode - XFER_PIO_0;
  	u8 cmd_pio = pio;
  
  	if (pair)
  		cmd_pio = min_t(u8, pio, pair->pio_mode - XFER_PIO_0);
  
  	timings &= (IDE_DRV_MASK << 8);
  	timings |= drv_timings[pio];
  	ide_set_drivedata(drive, (void *)timings);
  
  	cs5536_program_dtc(drive, drv_timings[pio]);
  
  	cs5536_read(pdev, CAST, &cast);
  
  	cast &= ~(IDE_CAST_DRV_MASK << cshift);
  	cast |= addr_timings[pio] << cshift;
  
  	cast &= ~(IDE_CAST_CMD_MASK << IDE_CAST_CMD_SHIFT);
  	cast |= cmd_timings[cmd_pio] << IDE_CAST_CMD_SHIFT;
  
  	cs5536_write(pdev, CAST, cast);
  }
  
  /**
   *	cs5536_set_dma_mode		-	DMA timing setup
   *	@hwif: ATA port
   *	@drive: ATA device
   */
  
  static void cs5536_set_dma_mode(ide_hwif_t *hwif, ide_drive_t *drive)
  {
  	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(hwif->dev);
  	int dshift = (drive->dn & 1) ? IDE_D1_SHIFT : IDE_D0_SHIFT;
  	unsigned long timings = (unsigned long)ide_get_drivedata(drive);
  	u32 etc;
  	const u8 mode = drive->dma_mode;
  
  	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);
  		timings &= IDE_DRV_MASK;
  		timings |= mwdma_timings[mode - XFER_MW_DMA_0] << 8;
  		ide_set_drivedata(drive, (void *)timings);
  	}
  
  	cs5536_write(pdev, ETC, etc);
  }
  
  static void cs5536_dma_start(ide_drive_t *drive)
  {
  	unsigned long timings = (unsigned long)ide_get_drivedata(drive);
  
  	if (drive->current_speed < XFER_UDMA_0 &&
  	    (timings >> 8) != (timings & IDE_DRV_MASK))
  		cs5536_program_dtc(drive, timings >> 8);
  
  	ide_dma_start(drive);
  }
  
  static int cs5536_dma_end(ide_drive_t *drive)
  {
  	int ret = ide_dma_end(drive);
  	unsigned long timings = (unsigned long)ide_get_drivedata(drive);
  
  	if (drive->current_speed < XFER_UDMA_0 &&
  	    (timings >> 8) != (timings & IDE_DRV_MASK))
  		cs5536_program_dtc(drive, timings & IDE_DRV_MASK);
  
  	return ret;
  }
  
  static const struct ide_port_ops cs5536_port_ops = {
  	.set_pio_mode		= cs5536_set_pio_mode,
  	.set_dma_mode		= cs5536_set_dma_mode,
  	.cable_detect		= cs5536_cable_detect,
  };
  
  static const struct ide_dma_ops cs5536_dma_ops = {
  	.dma_host_set		= ide_dma_host_set,
  	.dma_setup		= ide_dma_setup,
  	.dma_start		= cs5536_dma_start,
  	.dma_end		= cs5536_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,
  };
  
  static const struct ide_port_info cs5536_info = {
  	.name		= DRV_NAME,
  	.port_ops	= &cs5536_port_ops,
  	.dma_ops	= &cs5536_dma_ops,
  	.host_flags	= IDE_HFLAG_SINGLE,
  	.pio_mask	= ATA_PIO4,
  	.mwdma_mask	= ATA_MWDMA2,
  	.udma_mask	= ATA_UDMA5,
  };
  
  /**
   *	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)
  {
  	u32 cfg;
  
  	if (use_msr)
  		printk(KERN_INFO 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 ide_pci_init_one(dev, &cs5536_info, NULL);
  }
  
  static const struct pci_device_id cs5536_pci_tbl[] = {
  	{ PCI_VDEVICE(AMD, PCI_DEVICE_ID_AMD_CS5536_IDE), },
  	{ },
  };
  
  static struct pci_driver cs5536_pci_driver = {
  	.name		= DRV_NAME,
  	.id_table	= cs5536_pci_tbl,
  	.probe		= cs5536_init_one,
  	.remove		= ide_pci_remove,
  	.suspend	= ide_pci_suspend,
  	.resume		= ide_pci_resume,
  };
  
  module_pci_driver(cs5536_pci_driver);
  
  MODULE_AUTHOR("Martin K. Petersen, Bartlomiej Zolnierkiewicz");
  MODULE_DESCRIPTION("low-level driver for the CS5536 IDE controller");
  MODULE_LICENSE("GPL");
  MODULE_DEVICE_TABLE(pci, cs5536_pci_tbl);
  
  module_param_named(msr, use_msr, int, 0644);
  MODULE_PARM_DESC(msr, "Force using MSR to configure IDE function (Default: 0)");