/*
       *  linux/drivers/ide/cmd640.c		Version 1.02  Sep 01, 1996
       *
       *  Copyright (C) 1995-1996  Linus Torvalds & authors (see below)
       */
      
      /*
       *  Original authors:	abramov@cecmow.enet.dec.com (Igor Abramov)
       *  			mlord@pobox.com (Mark Lord)
       *
       *  See linux/MAINTAINERS for address of current maintainer.
       *
       *  This file provides support for the advanced features and bugs
       *  of IDE interfaces using the CMD Technologies 0640 IDE interface chip.
       *
       *  These chips are basically fucked by design, and getting this driver
       *  to work on every motherboard design that uses this screwed chip seems
       *  bloody well impossible.  However, we're still trying.
       *
       *  Version 0.97 worked for everybody.
       *
       *  User feedback is essential.  Many thanks to the beta test team:
       *
       *  A.Hartgers@stud.tue.nl, JZDQC@CUNYVM.CUNY.edu, abramov@cecmow.enet.dec.com,
       *  bardj@utopia.ppp.sn.no, bart@gaga.tue.nl, bbol001@cs.auckland.ac.nz,
       *  chrisc@dbass.demon.co.uk, dalecki@namu26.Num.Math.Uni-Goettingen.de,
       *  derekn@vw.ece.cmu.edu, florian@btp2x3.phy.uni-bayreuth.de,
       *  flynn@dei.unipd.it, gadio@netvision.net.il, godzilla@futuris.net,
       *  j@pobox.com, jkemp1@mises.uni-paderborn.de, jtoppe@hiwaay.net,
       *  kerouac@ssnet.com, meskes@informatik.rwth-aachen.de, hzoli@cs.elte.hu,
       *  peter@udgaard.isgtec.com, phil@tazenda.demon.co.uk, roadcapw@cfw.com,
       *  s0033las@sun10.vsz.bme.hu, schaffer@tam.cornell.edu, sjd@slip.net,
       *  steve@ei.org, ulrpeg@bigcomm.gun.de, ism@tardis.ed.ac.uk, mack@cray.com
       *  liug@mama.indstate.edu, and others.
       *
       *  Version 0.01	Initial version, hacked out of ide.c,
       *			and #include'd rather than compiled separately.
       *			This will get cleaned up in a subsequent release.
       *
       *  Version 0.02	Fixes for vlb initialization code, enable prefetch
       *			for versions 'B' and 'C' of chip by default,
       *			some code cleanup.
       *
       *  Version 0.03	Added reset of secondary interface,
       *			and black list for devices which are not compatible
       *			with prefetch mode. Separate function for setting
       *			prefetch is added, possibly it will be called some
       *			day from ioctl processing code.
       *
       *  Version 0.04	Now configs/compiles separate from ide.c
       *
       *  Version 0.05	Major rewrite of interface timing code.
       *			Added new function cmd640_set_mode to set PIO mode
       *			from ioctl call. New drives added to black list.
       *
       *  Version 0.06	More code cleanup. Prefetch is enabled only for
       *			detected hard drives, not included in prefetch
       *			black list.
       *
       *  Version 0.07	Changed to more conservative drive tuning policy.
       *			Unknown drives, which report PIO < 4 are set to
       *			(reported_PIO - 1) if it is supported, or to PIO0.
       *			List of known drives extended by info provided by
       *			CMD at their ftp site.
       *
       *  Version 0.08	Added autotune/noautotune support.
       *
       *  Version 0.09	Try to be smarter about 2nd port enabling.
       *  Version 0.10	Be nice and don't reset 2nd port.
       *  Version 0.11	Try to handle more wierd situations.
       *
       *  Version 0.12	Lots of bug fixes from Laszlo Peter
       *			irq unmasking disabled for reliability.
       *			try to be even smarter about the second port.
       *			tidy up source code formatting.
       *  Version 0.13	permit irq unmasking again.
       *  Version 0.90	massive code cleanup, some bugs fixed.
       *			defaults all drives to PIO mode0, prefetch off.
       *			autotune is OFF by default, with compile time flag.
       *			prefetch can be turned OFF/ON using "hdparm -p8/-p9"
       *			 (requires hdparm-3.1 or newer)
       *  Version 0.91	first release to linux-kernel list.
       *  Version 0.92	move initial reg dump to separate callable function
       *			change "readahead" to "prefetch" to avoid confusion
       *  Version 0.95	respect original BIOS timings unless autotuning.
       *			tons of code cleanup and rearrangement.
       *			added CONFIG_BLK_DEV_CMD640_ENHANCED option
       *			prevent use of unmask when prefetch is on
       *  Version 0.96	prevent use of io_32bit when prefetch is off
       *  Version 0.97	fix VLB secondary interface for sjd@slip.net
       *			other minor tune-ups:  0.96 was very good.
       *  Version 0.98	ignore PCI version when disabled by BIOS
       *  Version 0.99	display setup/active/recovery clocks with PIO mode
       *  Version 1.00	Mmm.. cannot depend on PCMD_ENA in all systems
       *  Version 1.01	slow/fast devsel can be selected with "hdparm -p6/-p7"
       *			 ("fast" is necessary for 32bit I/O in some systems)
       *  Version 1.02	fix bug that resulted in slow "setup times"
       *			 (patch courtesy of Zoltan Hidvegi)
       */
      
      #undef REALLY_SLOW_IO		/* most systems can safely undef this */
      #define CMD640_PREFETCH_MASKS 1
      
      #include <linux/config.h>
      #include <linux/types.h>
      #include <linux/kernel.h>
      #include <linux/delay.h>
      #include <linux/timer.h>
      #include <linux/mm.h>
      #include <linux/ioport.h>
      #include <linux/blkdev.h>
      #include <linux/hdreg.h>
      #include <linux/ide.h>
      #include <linux/init.h>
      
      #include <asm/io.h>
      
      #include "ide_modes.h"
      
      /*
       * This flag is set in ide.c by the parameter:  ide0=cmd640_vlb
       */
      int cmd640_vlb = 0;
      
      /*
       * CMD640 specific registers definition.
       */
      
      #define VID		0x00
      #define DID		0x02
      #define PCMD		0x04
      #define   PCMD_ENA	0x01
      #define PSTTS		0x06
      #define REVID		0x08
      #define PROGIF		0x09
      #define SUBCL		0x0a
      #define BASCL		0x0b
      #define BaseA0		0x10
      #define BaseA1		0x14
      #define BaseA2		0x18
      #define BaseA3		0x1c
      #define INTLINE		0x3c
      #define INPINE		0x3d
      
      #define	CFR		0x50
      #define   CFR_DEVREV		0x03
      #define   CFR_IDE01INTR		0x04
      #define	  CFR_DEVID		0x18
      #define	  CFR_AT_VESA_078h	0x20
      #define	  CFR_DSA1		0x40
      #define	  CFR_DSA0		0x80
      
      #define CNTRL		0x51
      #define	  CNTRL_DIS_RA0		0x40
      #define   CNTRL_DIS_RA1		0x80
      #define	  CNTRL_ENA_2ND		0x08
      
      #define	CMDTIM		0x52
      #define	ARTTIM0		0x53
      #define	DRWTIM0		0x54
      #define ARTTIM1 	0x55
      #define DRWTIM1		0x56
      #define ARTTIM23	0x57
      #define   ARTTIM23_DIS_RA2	0x04
      #define   ARTTIM23_DIS_RA3	0x08
      #define DRWTIM23	0x58
      #define BRST		0x59
      
      /*
       * Registers and masks for easy access by drive index:
       */
      static byte prefetch_regs[4]  = {CNTRL, CNTRL, ARTTIM23, ARTTIM23};
      static byte prefetch_masks[4] = {CNTRL_DIS_RA0, CNTRL_DIS_RA1, ARTTIM23_DIS_RA2, ARTTIM23_DIS_RA3};
      
      #ifdef CONFIG_BLK_DEV_CMD640_ENHANCED
      
      static byte arttim_regs[4] = {ARTTIM0, ARTTIM1, ARTTIM23, ARTTIM23};
      static byte drwtim_regs[4] = {DRWTIM0, DRWTIM1, DRWTIM23, DRWTIM23};
      
      /*
       * Current cmd640 timing values for each drive.
       * The defaults for each are the slowest possible timings.
       */
      static byte setup_counts[4]    = {4, 4, 4, 4};     /* Address setup count (in clocks) */
      static byte active_counts[4]   = {16, 16, 16, 16}; /* Active count   (encoded) */
      static byte recovery_counts[4] = {16, 16, 16, 16}; /* Recovery count (encoded) */
      
      #endif /* CONFIG_BLK_DEV_CMD640_ENHANCED */
      
      /*
       * These are initialized to point at the devices we control
       */
      static ide_hwif_t  *cmd_hwif0, *cmd_hwif1;
      static ide_drive_t *cmd_drives[4];
      
      /*
       * Interface to access cmd640x registers
       */
      static unsigned int cmd640_key;
      static void (*put_cmd640_reg)(unsigned short reg, byte val);
      static byte (*get_cmd640_reg)(unsigned short reg);
      
      /*
       * This is read from the CFR reg, and is used in several places.
       */
      static unsigned int cmd640_chip_version;
      
      /*
       * The CMD640x chip does not support DWORD config write cycles, but some
       * of the BIOSes use them to implement the config services.
       * Therefore, we must use direct IO instead.
       */
      
      /* PCI method 1 access */
      
 216  static void put_cmd640_reg_pci1 (unsigned short reg, byte val)
      {
      	unsigned long flags;
      
      	save_flags(flags);
      	cli();
      	outl_p((reg & 0xfc) | cmd640_key, 0xcf8);
      	outb_p(val, (reg & 3) | 0xcfc);
      	restore_flags(flags);
      }
      
 227  static byte get_cmd640_reg_pci1 (unsigned short reg)
      {
      	byte b;
      	unsigned long flags;
      
      	save_flags(flags);
      	cli();
      	outl_p((reg & 0xfc) | cmd640_key, 0xcf8);
      	b = inb_p((reg & 3) | 0xcfc);
      	restore_flags(flags);
 237  	return b;
      }
      
      /* PCI method 2 access (from CMD datasheet) */
      
 242  static void put_cmd640_reg_pci2 (unsigned short reg, byte val)
      {
      	unsigned long flags;
      
      	save_flags(flags);
      	cli();
      	outb_p(0x10, 0xcf8);
      	outb_p(val, cmd640_key + reg);
      	outb_p(0, 0xcf8);
      	restore_flags(flags);
      }
      
 254  static byte get_cmd640_reg_pci2 (unsigned short reg)
      {
      	byte b;
      	unsigned long flags;
      
      	save_flags(flags);
      	cli();
      	outb_p(0x10, 0xcf8);
      	b = inb_p(cmd640_key + reg);
      	outb_p(0, 0xcf8);
      	restore_flags(flags);
 265  	return b;
      }
      
      /* VLB access */
      
 270  static void put_cmd640_reg_vlb (unsigned short reg, byte val)
      {
      	unsigned long flags;
      
      	save_flags(flags);
      	cli();
      	outb_p(reg, cmd640_key);
      	outb_p(val, cmd640_key + 4);
      	restore_flags(flags);
      }
      
 281  static byte get_cmd640_reg_vlb (unsigned short reg)
      {
      	byte b;
      	unsigned long flags;
      
      	save_flags(flags);
      	cli();
      	outb_p(reg, cmd640_key);
      	b = inb_p(cmd640_key + 4);
      	restore_flags(flags);
 291  	return b;
      }
      
 294  static int __init match_pci_cmd640_device (void)
      {
      	const byte ven_dev[4] = {0x95, 0x10, 0x40, 0x06};
      	unsigned int i;
 298  	for (i = 0; i < 4; i++) {
 299  		if (get_cmd640_reg(i) != ven_dev[i])
 300  			return 0;
      	}
      #ifdef STUPIDLY_TRUST_BROKEN_PCMD_ENA_BIT
      	if ((get_cmd640_reg(PCMD) & PCMD_ENA) == 0) {
      		printk("ide: cmd640 on PCI disabled by BIOS\n");
      		return 0;
      	}
      #endif /* STUPIDLY_TRUST_BROKEN_PCMD_ENA_BIT */
 308  	return 1; /* success */
      }
      
      /*
       * Probe for CMD640x -- pci method 1
       */
 314  static int __init probe_for_cmd640_pci1 (void)
      {
      	get_cmd640_reg = get_cmd640_reg_pci1;
      	put_cmd640_reg = put_cmd640_reg_pci1;
 318  	for (cmd640_key = 0x80000000; cmd640_key <= 0x8000f800; cmd640_key += 0x800) {
 319  		if (match_pci_cmd640_device())
 320  			return 1; /* success */
      	}
 322  	return 0;
      }
      
      /*
       * Probe for CMD640x -- pci method 2
       */
 328  static int __init probe_for_cmd640_pci2 (void)
      {
      	get_cmd640_reg = get_cmd640_reg_pci2;
      	put_cmd640_reg = put_cmd640_reg_pci2;
 332  	for (cmd640_key = 0xc000; cmd640_key <= 0xcf00; cmd640_key += 0x100) {
 333  		if (match_pci_cmd640_device())
 334  			return 1; /* success */
      	}
 336  	return 0;
      }
      
      /*
       * Probe for CMD640x -- vlb
       */
 342  static int __init probe_for_cmd640_vlb (void)
      {
      	byte b;
      
      	get_cmd640_reg = get_cmd640_reg_vlb;
      	put_cmd640_reg = put_cmd640_reg_vlb;
      	cmd640_key = 0x178;
      	b = get_cmd640_reg(CFR);
 350  	if (b == 0xff || b == 0x00 || (b & CFR_AT_VESA_078h)) {
      		cmd640_key = 0x78;
      		b = get_cmd640_reg(CFR);
 353  		if (b == 0xff || b == 0x00 || !(b & CFR_AT_VESA_078h))
 354  			return 0;
      	}
 356  	return 1; /* success */
      }
      
      /*
       *  Returns 1 if an IDE interface/drive exists at 0x170,
       *  Returns 0 otherwise.
       */
 363  static int __init secondary_port_responding (void)
      {
      	unsigned long flags;
      
      	save_flags(flags);
      	cli();
      
      	outb_p(0x0a, 0x170 + IDE_SELECT_OFFSET);	/* select drive0 */
      	udelay(100);
 372  	if ((inb_p(0x170 + IDE_SELECT_OFFSET) & 0x1f) != 0x0a) {
      		outb_p(0x1a, 0x170 + IDE_SELECT_OFFSET); /* select drive1 */
      		udelay(100);
 375  		if ((inb_p(0x170 + IDE_SELECT_OFFSET) & 0x1f) != 0x1a) {
      			restore_flags(flags);
 377  			return 0; /* nothing responded */
      		}
      	}
      	restore_flags(flags);
 381  	return 1; /* success */
      }
      
      #ifdef CMD640_DUMP_REGS
      /*
       * Dump out all cmd640 registers.  May be called from ide.c
       */
      void cmd640_dump_regs (void)
      {
      	unsigned int reg = cmd640_vlb ? 0x50 : 0x00;
      
      	/* Dump current state of chip registers */
      	printk("ide: cmd640 internal register dump:");
      	for (; reg <= 0x59; reg++) {
      		if (!(reg & 0x0f))
      			printk("\n%04x:", reg);
      		printk(" %02x", get_cmd640_reg(reg));
      	}
      	printk("\n");
      }
      #endif
      
      /*
       * Check whether prefetch is on for a drive,
       * and initialize the unmask flags for safe operation.
       */
 407  static void __init check_prefetch (unsigned int index)
      {
      	ide_drive_t *drive = cmd_drives[index];
      	byte b = get_cmd640_reg(prefetch_regs[index]);
      
 412  	if (b & prefetch_masks[index]) {	/* is prefetch off? */
      		drive->no_unmask = 0;
      		drive->no_io_32bit = 1;
      		drive->io_32bit = 0;
 416  	} else {
      #if CMD640_PREFETCH_MASKS
      		drive->no_unmask = 1;
      		drive->unmask = 0;
      #endif
      		drive->no_io_32bit = 0;
      	}
      }
      
      /*
       * Figure out which devices we control
       */
 428  static void __init setup_device_ptrs (void)
      {
      	unsigned int i;
      
      	cmd_hwif0 = &ide_hwifs[0]; /* default, if not found below */
      	cmd_hwif1 = &ide_hwifs[1]; /* default, if not found below */
 434  	for (i = 0; i < MAX_HWIFS; i++) {
      		ide_hwif_t *hwif = &ide_hwifs[i];
 436  		if (hwif->chipset == ide_unknown || hwif->chipset == ide_generic) {
 437  			if (hwif->io_ports[IDE_DATA_OFFSET] == 0x1f0)
      				cmd_hwif0 = hwif;
 439  			else if (hwif->io_ports[IDE_DATA_OFFSET] == 0x170)
      				cmd_hwif1 = hwif;
      		}
      	}
      	cmd_drives[0] = &cmd_hwif0->drives[0];
      	cmd_drives[1] = &cmd_hwif0->drives[1];
      	cmd_drives[2] = &cmd_hwif1->drives[0];
      	cmd_drives[3] = &cmd_hwif1->drives[1];
      }
      
      #ifdef CONFIG_BLK_DEV_CMD640_ENHANCED
      
      /*
       * Sets prefetch mode for a drive.
       */
      static void set_prefetch_mode (unsigned int index, int mode)
      {
      	ide_drive_t *drive = cmd_drives[index];
      	int reg = prefetch_regs[index];
      	byte b;
      	unsigned long flags;
      
      	save_flags(flags);
      	cli();
      	b = get_cmd640_reg(reg);
      	if (mode) {	/* want prefetch on? */
      #if CMD640_PREFETCH_MASKS
      		drive->no_unmask = 1;
      		drive->unmask = 0;
      #endif
      		drive->no_io_32bit = 0;
      		b &= ~prefetch_masks[index];	/* enable prefetch */
      	} else {
      		drive->no_unmask = 0;
      		drive->no_io_32bit = 1;
      		drive->io_32bit = 0;
      		b |= prefetch_masks[index];	/* disable prefetch */
      	}
      	put_cmd640_reg(reg, b);
      	restore_flags(flags);
      }
      
      /*
       * Dump out current drive clocks settings
       */
      static void display_clocks (unsigned int index)
      {
      	byte active_count, recovery_count;
      
      	active_count = active_counts[index];
      	if (active_count == 1)
      		++active_count;
      	recovery_count = recovery_counts[index];
      	if (active_count > 3 && recovery_count == 1)
      		++recovery_count;
      	if (cmd640_chip_version > 1)
      		recovery_count += 1;  /* cmd640b uses (count + 1)*/
      	printk(", clocks=%d/%d/%d\n", setup_counts[index], active_count, recovery_count);
      }
      
      /*
       * Pack active and recovery counts into single byte representation
       * used by controller
       */
      inline static byte pack_nibbles (byte upper, byte lower)
      {
      	return ((upper & 0x0f) << 4) | (lower & 0x0f);
      }
      
      /*
       * This routine retrieves the initial drive timings from the chipset.
       */
      static void __init retrieve_drive_counts (unsigned int index)
      {
      	byte b;
      
      	/*
      	 * Get the internal setup timing, and convert to clock count
      	 */
      	b = get_cmd640_reg(arttim_regs[index]) & ~0x3f;
      	switch (b) {
      		case 0x00: b = 4; break;
      		case 0x80: b = 3; break;
      		case 0x40: b = 2; break;
      		default:   b = 5; break;
      	}
      	setup_counts[index] = b;
      
      	/*
      	 * Get the active/recovery counts
      	 */
      	b = get_cmd640_reg(drwtim_regs[index]);
      	active_counts[index]   = (b >> 4)   ? (b >> 4)   : 0x10;
      	recovery_counts[index] = (b & 0x0f) ? (b & 0x0f) : 0x10;
      }
      
      
      /*
       * This routine writes the prepared setup/active/recovery counts
       * for a drive into the cmd640 chipset registers to active them.
       */
      static void program_drive_counts (unsigned int index)
      {
      	unsigned long flags;
      	byte setup_count    = setup_counts[index];
      	byte active_count   = active_counts[index];
      	byte recovery_count = recovery_counts[index];
      
      	/*
      	 * Set up address setup count and drive read/write timing registers.
      	 * Primary interface has individual count/timing registers for
      	 * each drive.  Secondary interface has one common set of registers,
      	 * so we merge the timings, using the slowest value for each timing.
      	 */
      	if (index > 1) {
      		unsigned int mate;
      		if (cmd_drives[mate = index ^ 1]->present) {
      			if (setup_count < setup_counts[mate])
      				setup_count = setup_counts[mate];
      			if (active_count < active_counts[mate])
      				active_count = active_counts[mate];
      			if (recovery_count < recovery_counts[mate])
      				recovery_count = recovery_counts[mate];
      		}
      	}
      
      	/*
      	 * Convert setup_count to internal chipset representation
      	 */
      	switch (setup_count) {
      		case 4:	 setup_count = 0x00; break;
      		case 3:	 setup_count = 0x80; break;
      		case 1:
      		case 2:	 setup_count = 0x40; break;
      		default: setup_count = 0xc0; /* case 5 */
      	}
      
      	/*
      	 * Now that everything is ready, program the new timings
      	 */
      	save_flags (flags);
      	cli();
      	/*
      	 * Program the address_setup clocks into ARTTIM reg,
      	 * and then the active/recovery counts into the DRWTIM reg
      	 * (this converts counts of 16 into counts of zero -- okay).
      	 */
      	setup_count |= get_cmd640_reg(arttim_regs[index]) & 0x3f;
      	put_cmd640_reg(arttim_regs[index], setup_count);
      	put_cmd640_reg(drwtim_regs[index], pack_nibbles(active_count, recovery_count));
      	restore_flags(flags);
      }
      
      /*
       * Set a specific pio_mode for a drive
       */
      static void cmd640_set_mode (unsigned int index, byte pio_mode, unsigned int cycle_time)
      {
      	int setup_time, active_time, recovery_time, clock_time;
      	byte setup_count, active_count, recovery_count, recovery_count2, cycle_count;
      	int bus_speed = system_bus_clock();
      
      	if (pio_mode > 5)
      		pio_mode = 5;
      	setup_time  = ide_pio_timings[pio_mode].setup_time;
      	active_time = ide_pio_timings[pio_mode].active_time;
      	recovery_time = cycle_time - (setup_time + active_time);
      	clock_time = 1000 / bus_speed;
      	cycle_count = (cycle_time + clock_time - 1) / clock_time;
      
      	setup_count = (setup_time + clock_time - 1) / clock_time;
      
      	active_count = (active_time + clock_time - 1) / clock_time;
      	if (active_count < 2)
      		active_count = 2; /* minimum allowed by cmd640 */
      
      	recovery_count = (recovery_time + clock_time - 1) / clock_time;
      	recovery_count2 = cycle_count - (setup_count + active_count);
      	if (recovery_count2 > recovery_count)
      		recovery_count = recovery_count2;
      	if (recovery_count < 2)
      		recovery_count = 2; /* minimum allowed by cmd640 */
      	if (recovery_count > 17) {
      		active_count += recovery_count - 17;
      		recovery_count = 17;
      	}
      	if (active_count > 16)
      		active_count = 16; /* maximum allowed by cmd640 */
      	if (cmd640_chip_version > 1)
      		recovery_count -= 1;  /* cmd640b uses (count + 1)*/
      	if (recovery_count > 16)
      		recovery_count = 16; /* maximum allowed by cmd640 */
      
      	setup_counts[index]    = setup_count;
      	active_counts[index]   = active_count;
      	recovery_counts[index] = recovery_count;
      
      	/*
      	 * In a perfect world, we might set the drive pio mode here
      	 * (using WIN_SETFEATURE) before continuing.
      	 *
      	 * But we do not, because:
      	 *	1) this is the wrong place to do it (proper is do_special() in ide.c)
      	 * 	2) in practice this is rarely, if ever, necessary
      	 */
      	program_drive_counts (index);
      }
      
      /*
       * Drive PIO mode selection:
       */
      static void cmd640_tune_drive (ide_drive_t *drive, byte mode_wanted)
      {
      	byte b;
      	ide_pio_data_t  d;
      	unsigned int index = 0;
      
      	while (drive != cmd_drives[index]) {
      		if (++index > 3) {
      			printk("%s: bad news in cmd640_tune_drive\n", drive->name);
      			return;
      		}
      	}
      	switch (mode_wanted) {
      		case 6: /* set fast-devsel off */
      		case 7: /* set fast-devsel on */
      			mode_wanted &= 1;
      			b = get_cmd640_reg(CNTRL) & ~0x27;
      			if (mode_wanted)
      				b |= 0x27;
      			put_cmd640_reg(CNTRL, b);
      			printk("%s: %sabled cmd640 fast host timing (devsel)\n", drive->name, mode_wanted ? "en" : "dis");
      			return;
      
      		case 8: /* set prefetch off */
      		case 9: /* set prefetch on */
      			mode_wanted &= 1;
      			set_prefetch_mode(index, mode_wanted);
      			printk("%s: %sabled cmd640 prefetch\n", drive->name, mode_wanted ? "en" : "dis");
      			return;
      	}
      
      	(void) ide_get_best_pio_mode (drive, mode_wanted, 5, &d);
      	cmd640_set_mode (index, d.pio_mode, d.cycle_time);
      
      	printk ("%s: selected cmd640 PIO mode%d (%dns)%s",
      		drive->name,
      		d.pio_mode,
      		d.cycle_time,
      		d.overridden ? " (overriding vendor mode)" : "");
      	display_clocks(index);
      	return;
      }
      
      #endif /* CONFIG_BLK_DEV_CMD640_ENHANCED */
      
      /*
       * Probe for a cmd640 chipset, and initialize it if found.  Called from ide.c
       */
 698  int __init ide_probe_for_cmd640x (void)
      {
      #ifdef CONFIG_BLK_DEV_CMD640_ENHANCED
      	int second_port_toggled = 0;
      #endif /* CONFIG_BLK_DEV_CMD640_ENHANCED */
      	int second_port_cmd640 = 0;
      	const char *bus_type, *port2;
      	unsigned int index;
      	byte b, cfr;
      
 708  	if (cmd640_vlb && probe_for_cmd640_vlb()) {
      		bus_type = "VLB";
 710  	} else {
      		cmd640_vlb = 0;
 712  		if (probe_for_cmd640_pci1())
      			bus_type = "PCI (type1)";
 714  		else if (probe_for_cmd640_pci2())
      			bus_type = "PCI (type2)";
 716  		else
 717  			return 0;
      	}
      	/*
      	 * Undocumented magic (there is no 0x5b reg in specs)
      	 */
      	put_cmd640_reg(0x5b, 0xbd);
 723  	if (get_cmd640_reg(0x5b) != 0xbd) {
      		printk("ide: cmd640 init failed: wrong value in reg 0x5b\n");
 725  		return 0;
      	}
      	put_cmd640_reg(0x5b, 0);
      
      #ifdef CMD640_DUMP_REGS
      	CMD640_DUMP_REGS;
      #endif
      
      	/*
      	 * Documented magic begins here
      	 */
      	cfr = get_cmd640_reg(CFR);
      	cmd640_chip_version = cfr & CFR_DEVREV;
 738  	if (cmd640_chip_version == 0) {
      		printk ("ide: bad cmd640 revision: %d\n", cmd640_chip_version);
 740  		return 0;
      	}
      
      	/*
      	 * Initialize data for primary port
      	 */
      	setup_device_ptrs ();
      	printk("%s: buggy cmd640%c interface on %s, config=0x%02x\n",
      	       cmd_hwif0->name, 'a' + cmd640_chip_version - 1, bus_type, cfr);
      	cmd_hwif0->chipset = ide_cmd640;
      #ifdef CONFIG_BLK_DEV_CMD640_ENHANCED
      	cmd_hwif0->tuneproc = &cmd640_tune_drive;
      #endif /* CONFIG_BLK_DEV_CMD640_ENHANCED */
      
      	/*
      	 * Ensure compatibility by always using the slowest timings
      	 * for access to the drive's command register block,
      	 * and reset the prefetch burstsize to default (512 bytes).
      	 *
      	 * Maybe we need a way to NOT do these on *some* systems?
      	 */
      	put_cmd640_reg(CMDTIM, 0);
      	put_cmd640_reg(BRST, 0x40);
      
      	/*
      	 * Try to enable the secondary interface, if not already enabled
      	 */
 767  	if (cmd_hwif1->noprobe) {
      		port2 = "not probed";
 769  	} else {
      		b = get_cmd640_reg(CNTRL);
 771  		if (secondary_port_responding()) {
 772  			if ((b & CNTRL_ENA_2ND)) {
      				second_port_cmd640 = 1;
      				port2 = "okay";
 775  			} else if (cmd640_vlb) {
      				second_port_cmd640 = 1;
      				port2 = "alive";
 778  			} else
      				port2 = "not cmd640";
 780  		} else {
      			put_cmd640_reg(CNTRL, b ^ CNTRL_ENA_2ND); /* toggle the bit */
 782  			if (secondary_port_responding()) {
      				second_port_cmd640 = 1;
      #ifdef CONFIG_BLK_DEV_CMD640_ENHANCED
      				second_port_toggled = 1;
      #endif /* CONFIG_BLK_DEV_CMD640_ENHANCED */
      				port2 = "enabled";
 788  			} else {
      				put_cmd640_reg(CNTRL, b); /* restore original setting */
      				port2 = "not responding";
      			}
      		}
      	}
      
      	/*
      	 * Initialize data for secondary cmd640 port, if enabled
      	 */
 798  	if (second_port_cmd640) {
      		cmd_hwif0->serialized = 1;
      		cmd_hwif1->serialized = 1;
      		cmd_hwif1->chipset = ide_cmd640;
      		cmd_hwif0->mate = cmd_hwif1;
      		cmd_hwif1->mate = cmd_hwif0;
      		cmd_hwif1->channel = 1;
      #ifdef CONFIG_BLK_DEV_CMD640_ENHANCED
      		cmd_hwif1->tuneproc = &cmd640_tune_drive;
      #endif /* CONFIG_BLK_DEV_CMD640_ENHANCED */
      	}
      	printk("%s: %sserialized, secondary interface %s\n", cmd_hwif1->name,
      		cmd_hwif0->serialized ? "" : "not ", port2);
      
      	/*
      	 * Establish initial timings/prefetch for all drives.
      	 * Do not unnecessarily disturb any prior BIOS setup of these.
      	 */
 816  	for (index = 0; index < (2 + (second_port_cmd640 << 1)); index++) {
      		ide_drive_t *drive = cmd_drives[index];
      #ifdef CONFIG_BLK_DEV_CMD640_ENHANCED
      		if (drive->autotune || ((index > 1) && second_port_toggled)) {
      	 		/*
      	 		 * Reset timing to the slowest speed and turn off prefetch.
      			 * This way, the drive identify code has a better chance.
      			 */
      			setup_counts    [index] = 4;	/* max possible */
      			active_counts   [index] = 16;	/* max possible */
      			recovery_counts [index] = 16;	/* max possible */
      			program_drive_counts (index);
      			set_prefetch_mode (index, 0);
      			printk("cmd640: drive%d timings/prefetch cleared\n", index);
      		} else {
      			/*
      			 * Record timings/prefetch without changing them.
      			 * This preserves any prior BIOS setup.
      			 */
      			retrieve_drive_counts (index);
      			check_prefetch (index);
      			printk("cmd640: drive%d timings/prefetch(%s) preserved",
      				index, drive->no_io_32bit ? "off" : "on");
      			display_clocks(index);
      		}
      #else
      		/*
      		 * Set the drive unmask flags to match the prefetch setting
      		 */
      		check_prefetch (index);
      		printk("cmd640: drive%d timings/prefetch(%s) preserved\n",
      			index, drive->no_io_32bit ? "off" : "on");
      #endif /* CONFIG_BLK_DEV_CMD640_ENHANCED */
      	}
      
      #ifdef CMD640_DUMP_REGS
      	CMD640_DUMP_REGS;
      #endif
 854  	return 1;
      }