/*
 * Common Flash Interface support:
 *   AMD & Fujitsu Standard Vendor Command Set (ID 0x0002)
 *
 * Copyright (C) 2000 Crossnet Co. <info@crossnet.co.jp>
 * Copyright (C) 2004 Arcom Control Systems Ltd <linux@arcom.com>
 * Copyright (C) 2005 MontaVista Software Inc. <source@mvista.com>
 *
 * 2_by_8 routines added by Simon Munton
 *
 * 4_by_16 work by Carolyn J. Smith
 *
 * XIP support hooks by Vitaly Wool (based on code for Intel flash
 * by Nicolas Pitre)
 *
 * Occasionally maintained by Thayne Harbaugh tharbaugh at lnxi dot com
 *
 * This code is GPL
 *
 * $Id: cfi_cmdset_0002.c,v 1.122 2005/11/07 11:14:22 gleixner Exp $
 *
 */

#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <asm/io.h>
#include <asm/byteorder.h>

#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/mtd/compatmac.h>
#include <linux/mtd/map.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/cfi.h>
#include <linux/mtd/xip.h>

#define AMD_BOOTLOC_BUG
#define FORCE_WORD_WRITE 0

#define MAX_WORD_RETRIES 3

#define MANUFACTURER_AMD	0x0001
#define MANUFACTURER_ATMEL	0x001F
#define MANUFACTURER_SST	0x00BF
#define SST49LF004B	        0x0060
#define SST49LF040B	        0x0050
#define SST49LF008A		0x005a
#define AT49BV6416		0x00d6

static int cfi_amdstd_read (struct mtd_info *, loff_t, size_t, size_t *, u_char *);
static int cfi_amdstd_write_words(struct mtd_info *, loff_t, size_t, size_t *, const u_char *);
static int cfi_amdstd_write_buffers(struct mtd_info *, loff_t, size_t, size_t *, const u_char *);
static int cfi_amdstd_erase_chip(struct mtd_info *, struct erase_info *);
static int cfi_amdstd_erase_varsize(struct mtd_info *, struct erase_info *);
static void cfi_amdstd_sync (struct mtd_info *);
static int cfi_amdstd_suspend (struct mtd_info *);
static void cfi_amdstd_resume (struct mtd_info *);
static int cfi_amdstd_secsi_read (struct mtd_info *, loff_t, size_t, size_t *, u_char *);

static void cfi_amdstd_destroy(struct mtd_info *);

struct mtd_info *cfi_cmdset_0002(struct map_info *, int);
static struct mtd_info *cfi_amdstd_setup (struct mtd_info *);

static int get_chip(struct map_info *map, struct flchip *chip, unsigned long adr, int mode);
static void put_chip(struct map_info *map, struct flchip *chip, unsigned long adr);
#include "fwh_lock.h"

static int cfi_atmel_lock(struct mtd_info *mtd, loff_t ofs, size_t len);
static int cfi_atmel_unlock(struct mtd_info *mtd, loff_t ofs, size_t len);

static struct mtd_chip_driver cfi_amdstd_chipdrv = {
	.probe		= NULL, /* Not usable directly */
	.destroy	= cfi_amdstd_destroy,
	.name		= "cfi_cmdset_0002",
	.module		= THIS_MODULE
};


/* #define DEBUG_CFI_FEATURES */


#ifdef DEBUG_CFI_FEATURES
static void cfi_tell_features(struct cfi_pri_amdstd *extp)
{
	const char* erase_suspend[3] = {
		"Not supported", "Read only", "Read/write"
	};
	const char* top_bottom[6] = {
		"No WP", "8x8KiB sectors at top & bottom, no WP",
		"Bottom boot", "Top boot",
		"Uniform, Bottom WP", "Uniform, Top WP"
	};

	printk("  Silicon revision: %d\n", extp->SiliconRevision >> 1);
	printk("  Address sensitive unlock: %s\n",
	       (extp->SiliconRevision & 1) ? "Not required" : "Required");

	if (extp->EraseSuspend < ARRAY_SIZE(erase_suspend))
		printk("  Erase Suspend: %s\n", erase_suspend[extp->EraseSuspend]);
	else
		printk("  Erase Suspend: Unknown value %d\n", extp->EraseSuspend);

	if (extp->BlkProt == 0)
		printk("  Block protection: Not supported\n");
	else
		printk("  Block protection: %d sectors per group\n", extp->BlkProt);


	printk("  Temporary block unprotect: %s\n",
	       extp->TmpBlkUnprotect ? "Supported" : "Not supported");
	printk("  Block protect/unprotect scheme: %d\n", extp->BlkProtUnprot);
	printk("  Number of simultaneous operations: %d\n", extp->SimultaneousOps);
	printk("  Burst mode: %s\n",
	       extp->BurstMode ? "Supported" : "Not supported");
	if (extp->PageMode == 0)
		printk("  Page mode: Not supported\n");
	else
		printk("  Page mode: %d word page\n", extp->PageMode << 2);

	printk("  Vpp Supply Minimum Program/Erase Voltage: %d.%d V\n",
	       extp->VppMin >> 4, extp->VppMin & 0xf);
	printk("  Vpp Supply Maximum Program/Erase Voltage: %d.%d V\n",
	       extp->VppMax >> 4, extp->VppMax & 0xf);

	if (extp->TopBottom < ARRAY_SIZE(top_bottom))
		printk("  Top/Bottom Boot Block: %s\n", top_bottom[extp->TopBottom]);
	else
		printk("  Top/Bottom Boot Block: Unknown value %d\n", extp->TopBottom);
}
#endif

#ifdef AMD_BOOTLOC_BUG
/* Wheee. Bring me the head of someone at AMD. */
static void fixup_amd_bootblock(struct mtd_info *mtd, void* param)
{
	struct map_info *map = mtd->priv;
	struct cfi_private *cfi = map->fldrv_priv;
	struct cfi_pri_amdstd *extp = cfi->cmdset_priv;
	__u8 major = extp->MajorVersion;
	__u8 minor = extp->MinorVersion;

	if (((major << 8) | minor) < 0x3131) {
		/* CFI version 1.0 => don't trust bootloc */
		if (cfi->id & 0x80) {
			printk(KERN_WARNING "%s: JEDEC Device ID is 0x%02X. Assuming broken CFI table.\n", map->name, cfi->id);
			extp->TopBottom = 3;	/* top boot */
		} else {
			extp->TopBottom = 2;	/* bottom boot */
		}
	}
}
#endif

static void fixup_use_write_buffers(struct mtd_info *mtd, void *param)
{
	struct map_info *map = mtd->priv;
	struct cfi_private *cfi = map->fldrv_priv;
	if (cfi->cfiq->BufWriteTimeoutTyp) {
		DEBUG(MTD_DEBUG_LEVEL1, "Using buffer write method\n" );
		mtd->write = cfi_amdstd_write_buffers;
	}
}

/* Atmel chips don't use the same PRI format as AMD chips */
static void fixup_convert_atmel_pri(struct mtd_info *mtd, void *param)
{
	struct map_info *map = mtd->priv;
	struct cfi_private *cfi = map->fldrv_priv;
	struct cfi_pri_amdstd *extp = cfi->cmdset_priv;
	struct cfi_pri_atmel atmel_pri;

	memcpy(&atmel_pri, extp, sizeof(atmel_pri));
	memset((char *)extp + 5, 0, sizeof(*extp) - 5);

	if (atmel_pri.Features & 0x02)
		extp->EraseSuspend = 2;

	if (atmel_pri.BottomBoot)
		extp->TopBottom = 2;
	else
		extp->TopBottom = 3;

	/* burst write mode not supported */
	cfi->cfiq->BufWriteTimeoutTyp = 0;
	cfi->cfiq->BufWriteTimeoutMax = 0;
}

static void fixup_use_secsi(struct mtd_info *mtd, void *param)
{
	/* Setup for chips with a secsi area */
	mtd->read_user_prot_reg = cfi_amdstd_secsi_read;
	mtd->read_fact_prot_reg = cfi_amdstd_secsi_read;
}

static void fixup_use_erase_chip(struct mtd_info *mtd, void *param)
{
	struct map_info *map = mtd->priv;
	struct cfi_private *cfi = map->fldrv_priv;
	if ((cfi->cfiq->NumEraseRegions == 1) &&
		((cfi->cfiq->EraseRegionInfo[0] & 0xffff) == 0)) {
		mtd->erase = cfi_amdstd_erase_chip;
	}

}

/*
 * Some Atmel chips (e.g. the AT49BV6416) power-up with all sectors
 * locked by default.
 */
static void fixup_use_atmel_lock(struct mtd_info *mtd, void *param)
{
	mtd->lock = cfi_atmel_lock;
	mtd->unlock = cfi_atmel_unlock;
	mtd->flags |= MTD_POWERUP_LOCK;
}

static struct cfi_fixup cfi_fixup_table[] = {
	{ CFI_MFR_ATMEL, CFI_ID_ANY, fixup_convert_atmel_pri, NULL },
#ifdef AMD_BOOTLOC_BUG
	{ CFI_MFR_AMD, CFI_ID_ANY, fixup_amd_bootblock, NULL },
#endif
	{ CFI_MFR_AMD, 0x0050, fixup_use_secsi, NULL, },
	{ CFI_MFR_AMD, 0x0053, fixup_use_secsi, NULL, },
	{ CFI_MFR_AMD, 0x0055, fixup_use_secsi, NULL, },
	{ CFI_MFR_AMD, 0x0056, fixup_use_secsi, NULL, },
	{ CFI_MFR_AMD, 0x005C, fixup_use_secsi, NULL, },
	{ CFI_MFR_AMD, 0x005F, fixup_use_secsi, NULL, },
#if !FORCE_WORD_WRITE
	{ CFI_MFR_ANY, CFI_ID_ANY, fixup_use_write_buffers, NULL, },
#endif
	{ 0, 0, NULL, NULL }
};
static struct cfi_fixup jedec_fixup_table[] = {
	{ MANUFACTURER_SST, SST49LF004B, fixup_use_fwh_lock, NULL, },
	{ MANUFACTURER_SST, SST49LF040B, fixup_use_fwh_lock, NULL, },
	{ MANUFACTURER_SST, SST49LF008A, fixup_use_fwh_lock, NULL, },
	{ 0, 0, NULL, NULL }
};

static struct cfi_fixup fixup_table[] = {
	/* The CFI vendor ids and the JEDEC vendor IDs appear
	 * to be common.  It is like the devices id's are as
	 * well.  This table is to pick all cases where
	 * we know that is the case.
	 */
	{ CFI_MFR_ANY, CFI_ID_ANY, fixup_use_erase_chip, NULL },
	{ CFI_MFR_ATMEL, AT49BV6416, fixup_use_atmel_lock, NULL },
	{ 0, 0, NULL, NULL }
};


struct mtd_info *cfi_cmdset_0002(struct map_info *map, int primary)
{
	struct cfi_private *cfi = map->fldrv_priv;
	struct mtd_info *mtd;
	int i;

	mtd = kzalloc(sizeof(*mtd), GFP_KERNEL);
	if (!mtd) {
		printk(KERN_WARNING "Failed to allocate memory for MTD device\n");
		return NULL;
	}
	mtd->priv = map;
	mtd->type = MTD_NORFLASH;

	/* Fill in the default mtd operations */
	mtd->erase   = cfi_amdstd_erase_varsize;
	mtd->write   = cfi_amdstd_write_words;
	mtd->read    = cfi_amdstd_read;
	mtd->sync    = cfi_amdstd_sync;
	mtd->suspend = cfi_amdstd_suspend;
	mtd->resume  = cfi_amdstd_resume;
	mtd->flags   = MTD_CAP_NORFLASH;
	mtd->name    = map->name;
	mtd->writesize = 1;

	if (cfi->cfi_mode==CFI_MODE_CFI){
		unsigned char bootloc;
		/*
		 * It's a real CFI chip, not one for which the probe
		 * routine faked a CFI structure. So we read the feature
		 * table from it.
		 */
		__u16 adr = primary?cfi->cfiq->P_ADR:cfi->cfiq->A_ADR;
		struct cfi_pri_amdstd *extp;

		extp = (struct cfi_pri_amdstd*)cfi_read_pri(map, adr, sizeof(*extp), "Amd/Fujitsu");
		if (!extp) {
			kfree(mtd);
			return NULL;
		}

		if (extp->MajorVersion != '1' ||
		    (extp->MinorVersion < '0' || extp->MinorVersion > '4')) {
			printk(KERN_ERR "  Unknown Amd/Fujitsu Extended Query "
			       "version %c.%c.\n",  extp->MajorVersion,
			       extp->MinorVersion);
			kfree(extp);
			kfree(mtd);
			return NULL;
		}

		/* Install our own private info structure */
		cfi->cmdset_priv = extp;

		/* Apply cfi device specific fixups */
		cfi_fixup(mtd, cfi_fixup_table);

#ifdef DEBUG_CFI_FEATURES
		/* Tell the user about it in lots of lovely detail */
		cfi_tell_features(extp);
#endif

		bootloc = extp->TopBottom;
		if ((bootloc != 2) && (bootloc != 3)) {
			printk(KERN_WARNING "%s: CFI does not contain boot "
			       "bank location. Assuming top.\n", map->name);
			bootloc = 2;
		}

		if (bootloc == 3 && cfi->cfiq->NumEraseRegions > 1) {
			printk(KERN_WARNING "%s: Swapping erase regions for broken CFI table.\n", map->name);

			for (i=0; i<cfi->cfiq->NumEraseRegions / 2; i++) {
				int j = (cfi->cfiq->NumEraseRegions-1)-i;
				__u32 swap;

				swap = cfi->cfiq->EraseRegionInfo[i];
				cfi->cfiq->EraseRegionInfo[i] = cfi->cfiq->EraseRegionInfo[j];
				cfi->cfiq->EraseRegionInfo[j] = swap;
			}
		}
		/* Set the default CFI lock/unlock addresses */
		cfi->addr_unlock1 = 0x555;
		cfi->addr_unlock2 = 0x2aa;
		/* Modify the unlock address if we are in compatibility mode */
		if (	/* x16 in x8 mode */
			((cfi->device_type == CFI_DEVICETYPE_X8) &&
				(cfi->cfiq->InterfaceDesc ==
					CFI_INTERFACE_X8_BY_X16_ASYNC)) ||
			/* x32 in x16 mode */
			((cfi->device_type == CFI_DEVICETYPE_X16) &&
				(cfi->cfiq->InterfaceDesc ==
					CFI_INTERFACE_X16_BY_X32_ASYNC)))
		{
			cfi->addr_unlock1 = 0xaaa;
			cfi->addr_unlock2 = 0x555;
		}

	} /* CFI mode */
	else if (cfi->cfi_mode == CFI_MODE_JEDEC) {
		/* Apply jedec specific fixups */
		cfi_fixup(mtd, jedec_fixup_table);
	}
	/* Apply generic fixups */
	cfi_fixup(mtd, fixup_table);

	for (i=0; i< cfi->numchips; i++) {
		cfi->chips[i].word_write_time = 1<<cfi->cfiq->WordWriteTimeoutTyp;
		cfi->chips[i].buffer_write_time = 1<<cfi->cfiq->BufWriteTimeoutTyp;
		cfi->chips[i].erase_time = 1<<cfi->cfiq->BlockEraseTimeoutTyp;
		cfi->chips[i].ref_point_counter = 0;
		init_waitqueue_head(&(cfi->chips[i].wq));
	}

	map->fldrv = &cfi_amdstd_chipdrv;

	return cfi_amdstd_setup(mtd);
}
EXPORT_SYMBOL_GPL(cfi_cmdset_0002);

static struct mtd_info *cfi_amdstd_setup(struct mtd_info *mtd)
{
	struct map_info *map = mtd->priv;
	struct cfi_private *cfi = map->fldrv_priv;
	unsigned long devsize = (1<<cfi->cfiq->DevSize) * cfi->interleave;
	unsigned long offset = 0;
	int i,j;

	printk(KERN_NOTICE "number of %s chips: %d\n",
	       (cfi->cfi_mode == CFI_MODE_CFI)?"CFI":"JEDEC",cfi->numchips);
	/* Select the correct geometry setup */
	mtd->size = devsize * cfi->numchips;

	mtd->numeraseregions = cfi->cfiq->NumEraseRegions * cfi->numchips;
	mtd->eraseregions = kmalloc(sizeof(struct mtd_erase_region_info)
				    * mtd->numeraseregions, GFP_KERNEL);
	if (!mtd->eraseregions) {
		printk(KERN_WARNING "Failed to allocate memory for MTD erase region info\n");
		goto setup_err;
	}

	for (i=0; i<cfi->cfiq->NumEraseRegions; i++) {
		unsigned long ernum, ersize;
		ersize = ((cfi->cfiq->EraseRegionInfo[i] >> 8) & ~0xff) * cfi->interleave;
		ernum = (cfi->cfiq->EraseRegionInfo[i] & 0xffff) + 1;

		if (mtd->erasesize < ersize) {
			mtd->erasesize = ersize;
		}
		for (j=0; j<cfi->numchips; j++) {
			mtd->eraseregions[(j*cfi->cfiq->NumEraseRegions)+i].offset = (j*devsize)+offset;
			mtd->eraseregions[(j*cfi->cfiq->NumEraseRegions)+i].erasesize = ersize;
			mtd->eraseregions[(j*cfi->cfiq->NumEraseRegions)+i].numblocks = ernum;
		}
		offset += (ersize * ernum);
	}
	if (offset != devsize) {
		/* Argh */
		printk(KERN_WARNING "Sum of regions (%lx) != total size of set of interleaved chips (%lx)\n", offset, devsize);
		goto setup_err;
	}
#if 0
	// debug
	for (i=0; i<mtd->numeraseregions;i++){
		printk("%d: offset=0x%x,size=0x%x,blocks=%d\n",
		       i,mtd->eraseregions[i].offset,
		       mtd->eraseregions[i].erasesize,
		       mtd->eraseregions[i].numblocks);
	}
#endif

	/* FIXME: erase-suspend-program is broken.  See
	   http://lists.infradead.org/pipermail/linux-mtd/2003-December/009001.html */
	printk(KERN_NOTICE "cfi_cmdset_0002: Disabling erase-suspend-program due to code brokenness.\n");

	__module_get(THIS_MODULE);
	return mtd;

 setup_err:
	if(mtd) {
		kfree(mtd->eraseregions);
		kfree(mtd);
	}
	kfree(cfi->cmdset_priv);
	kfree(cfi->cfiq);
	return NULL;
}

/*
 * Return true if the chip is ready.
 *
 * Ready is one of: read mode, query mode, erase-suspend-read mode (in any
 * non-suspended sector) and is indicated by no toggle bits toggling.
 *
 * Note that anything more complicated than checking if no bits are toggling
 * (including checking DQ5 for an error status) is tricky to get working
 * correctly and is therefore not done	(particulary with interleaved chips
 * as each chip must be checked independantly of the others).
 */
static int __xipram chip_ready(struct map_info *map, unsigned long addr)
{
	map_word d, t;

	d = map_read(map, addr);
	t = map_read(map, addr);

	return map_word_equal(map, d, t);
}

/*
 * Return true if the chip is ready and has the correct value.
 *
 * Ready is one of: read mode, query mode, erase-suspend-read mode (in any
 * non-suspended sector) and it is indicated by no bits toggling.
 *
 * Error are indicated by toggling bits or bits held with the wrong value,
 * or with bits toggling.
 *
 * Note that anything more complicated than checking if no bits are toggling
 * (including checking DQ5 for an error status) is tricky to get working
 * correctly and is therefore not done	(particulary with interleaved chips
 * as each chip must be checked independantly of the others).
 *
 */
static int __xipram chip_good(struct map_info *map, unsigned long addr, map_word expected)
{
	map_word oldd, curd;

	oldd = map_read(map, addr);
	curd = map_read(map, addr);

	return	map_word_equal(map, oldd, curd) &&
		map_word_equal(map, curd, expected);
}

static int get_chip(struct map_info *map, struct flchip *chip, unsigned long adr, int mode)
{
	DECLARE_WAITQUEUE(wait, current);
	struct cfi_private *cfi = map->fldrv_priv;
	unsigned long timeo;
	struct cfi_pri_amdstd *cfip = (struct cfi_pri_amdstd *)cfi->cmdset_priv;

 resettime:
	timeo = jiffies + HZ;
 retry:
	switch (chip->state) {

	case FL_STATUS:
		for (;;) {
			if (chip_ready(map, adr))
				break;

			if (time_after(jiffies, timeo)) {
				printk(KERN_ERR "Waiting for chip to be ready timed out.\n");
				spin_unlock(chip->mutex);
				return -EIO;
			}
			spin_unlock(chip->mutex);
			cfi_udelay(1);
			spin_lock(chip->mutex);
			/* Someone else might have been playing with it. */
			goto retry;
		}

	case FL_READY:
	case FL_CFI_QUERY:
	case FL_JEDEC_QUERY:
		return 0;

	case FL_ERASING:
		if (mode == FL_WRITING) /* FIXME: Erase-suspend-program appears broken. */
			goto sleep;

		if (!(   mode == FL_READY
		      || mode == FL_POINT
		      || !cfip
		      || (mode == FL_WRITING && (cfip->EraseSuspend & 0x2))
		      || (mode == FL_WRITING && (cfip->EraseSuspend & 0x1)
		    )))
			goto sleep;

		/* We could check to see if we're trying to access the sector
		 * that is currently being erased. However, no user will try
		 * anything like that so we just wait for the timeout. */

		/* Erase suspend */
		/* It's harmless to issue the Erase-Suspend and Erase-Resume
		 * commands when the erase algorithm isn't in progress. */
		map_write(map, CMD(0xB0), chip->in_progress_block_addr);
		chip->oldstate = FL_ERASING;
		chip->state = FL_ERASE_SUSPENDING;
		chip->erase_suspended = 1;
		for (;;) {
			if (chip_ready(map, adr))
				break;

			if (time_after(jiffies, timeo)) {
				/* Should have suspended the erase by now.
				 * Send an Erase-Resume command as either
				 * there was an error (so leave the erase
				 * routine to recover from it) or we trying to
				 * use the erase-in-progress sector. */
				map_write(map, CMD(0x30), chip->in_progress_block_addr);
				chip->state = FL_ERASING;
				chip->oldstate = FL_READY;
				printk(KERN_ERR "MTD %s(): chip not ready after erase suspend\n", __func__);
				return -EIO;
			}

			spin_unlock(chip->mutex);
			cfi_udelay(1);
			spin_lock(chip->mutex);
			/* Nobody will touch it while it's in state FL_ERASE_SUSPENDING.
			   So we can just loop here. */
		}
		chip->state = FL_READY;
		return 0;

	case FL_XIP_WHILE_ERASING:
		if (mode != FL_READY && mode != FL_POINT &&
		    (!cfip || !(cfip->EraseSuspend&2)))
			goto sleep;
		chip->oldstate = chip->state;
		chip->state = FL_READY;
		return 0;

	case FL_POINT:
		/* Only if there's no operation suspended... */
		if (mode == FL_READY && chip->oldstate == FL_READY)
			return 0;

	default:
	sleep:
		set_current_state(TASK_UNINTERRUPTIBLE);
		add_wait_queue(&chip->wq, &wait);
		spin_unlock(chip->mutex);
		schedule();
		remove_wait_queue(&chip->wq, &wait);
		spin_lock(chip->mutex);
		goto resettime;
	}
}


static void put_chip(struct map_info *map, struct flchip *chip, unsigned long adr)
{
	struct cfi_private *cfi = map->fldrv_priv;

	switch(chip->oldstate) {
	case FL_ERASING:
		chip->state = chip->oldstate;
		map_write(map, CMD(0x30), chip->in_progress_block_addr);
		chip->oldstate = FL_READY;
		chip->state = FL_ERASING;
		break;

	case FL_XIP_WHILE_ERASING:
		chip->state = chip->oldstate;
		chip->oldstate = FL_READY;
		break;

	case FL_READY:
	case FL_STATUS:
		/* We should really make set_vpp() count, rather than doing this */
		DISABLE_VPP(map);
		break;
	default:
		printk(KERN_ERR "MTD: put_chip() called with oldstate %d!!\n", chip->oldstate);
	}
	wake_up(&chip->wq);
}

#ifdef CONFIG_MTD_XIP

/*
 * No interrupt what so ever can be serviced while the flash isn't in array
 * mode.  This is ensured by the xip_disable() and xip_enable() functions
 * enclosing any code path where the flash is known not to be in array mode.
 * And within a XIP disabled code path, only functions marked with __xipram
 * may be called and nothing else (it's a good thing to inspect generated
 * assembly to make sure inline functions were actually inlined and that gcc
 * didn't emit calls to its own support functions). Also configuring MTD CFI
 * support to a single buswidth and a single interleave is also recommended.
 */

static void xip_disable(struct map_info *map, struct flchip *chip,
			unsigned long adr)
{
	/* TODO: chips with no XIP use should ignore and return */
	(void) map_read(map, adr); /* ensure mmu mapping is up to date */
	local_irq_disable();
}

static void __xipram xip_enable(struct map_info *map, struct flchip *chip,
				unsigned long adr)
{
	struct cfi_private *cfi = map->fldrv_priv;

	if (chip->state != FL_POINT && chip->state != FL_READY) {
		map_write(map, CMD(0xf0), adr);
		chip->state = FL_READY;
	}
	(void) map_read(map, adr);
	xip_iprefetch();
	local_irq_enable();
}

/*
 * When a delay is required for the flash operation to complete, the
 * xip_udelay() function is polling for both the given timeout and pending
 * (but still masked) hardware interrupts.  Whenever there is an interrupt
 * pending then the flash erase operation is suspended, array mode restored
 * and interrupts unmasked.  Task scheduling might also happen at that
 * point.  The CPU eventually returns from the interrupt or the call to
 * schedule() and the suspended flash operation is resumed for the remaining
 * of the delay period.
 *
 * Warning: this function _will_ fool interrupt latency tracing tools.
 */

static void __xipram xip_udelay(struct map_info *map, struct flchip *chip,
				unsigned long adr, int usec)
{
	struct cfi_private *cfi = map->fldrv_priv;
	struct cfi_pri_amdstd *extp = cfi->cmdset_priv;
	map_word status, OK = CMD(0x80);
	unsigned long suspended, start = xip_currtime();
	flstate_t oldstate;

	do {
		cpu_relax();
		if (xip_irqpending() && extp &&
		    ((chip->state == FL_ERASING && (extp->EraseSuspend & 2))) &&
		    (cfi_interleave_is_1(cfi) || chip->oldstate == FL_READY)) {
			/*
			 * Let's suspend the erase operation when supported.
			 * Note that we currently don't try to suspend
			 * interleaved chips if there is already another
			 * operation suspended (imagine what happens
			 * when one chip was already done with the current
			 * operation while another chip suspended it, then
			 * we resume the whole thing at once).  Yes, it
			 * can happen!
			 */
			map_write(map, CMD(0xb0), adr);
			usec -= xip_elapsed_since(start);
			suspended = xip_currtime();
			do {
				if (xip_elapsed_since(suspended) > 100000) {
					/*
					 * The chip doesn't want to suspend
					 * after waiting for 100 msecs.
					 * This is a critical error but there
					 * is not much we can do here.
					 */
					return;
				}
				status = map_read(map, adr);
			} while (!map_word_andequal(map, status, OK, OK));

			/* Suspend succeeded */
			oldstate = chip->state;
			if (!map_word_bitsset(map, status, CMD(0x40)))
				break;
			chip->state = FL_XIP_WHILE_ERASING;
			chip->erase_suspended = 1;
			map_write(map, CMD(0xf0), adr);
			(void) map_read(map, adr);
			asm volatile (".rep 8; nop; .endr");
			local_irq_enable();
			spin_unlock(chip->mutex);
			asm volatile (".rep 8; nop; .endr");
			cond_resched();

			/*
			 * We're back.  However someone else might have
			 * decided to go write to the chip if we are in
			 * a suspended erase state.  If so let's wait
			 * until it's done.
			 */
			spin_lock(chip->mutex);
			while (chip->state != FL_XIP_WHILE_ERASING) {
				DECLARE_WAITQUEUE(wait, current);
				set_current_state(TASK_UNINTERRUPTIBLE);
				add_wait_queue(&chip->wq, &wait);
				spin_unlock(chip->mutex);
				schedule();
				remove_wait_queue(&chip->wq, &wait);
				spin_lock(chip->mutex);
			}
			/* Disallow XIP again */
			local_irq_disable();

			/* Resume the write or erase operation */
			map_write(map, CMD(0x30), adr);
			chip->state = oldstate;
			start = xip_currtime();
		} else if (usec >= 1000000/HZ) {
			/*
			 * Try to save on CPU power when waiting delay
			 * is at least a system timer tick period.
			 * No need to be extremely accurate here.
			 */
			xip_cpu_idle();
		}
		status = map_read(map, adr);
	} while (!map_word_andequal(map, status, OK, OK)
		 && xip_elapsed_since(start) < usec);
}

#define UDELAY(map, chip, adr, usec)  xip_udelay(map, chip, adr, usec)

/*
 * The INVALIDATE_CACHED_RANGE() macro is normally used in parallel while
 * the flash is actively programming or erasing since we have to poll for
 * the operation to complete anyway.  We can't do that in a generic way with
 * a XIP setup so do it before the actual flash operation in this case
 * and stub it out from INVALIDATE_CACHE_UDELAY.
 */
#define XIP_INVAL_CACHED_RANGE(map, from, size)  \
	INVALIDATE_CACHED_RANGE(map, from, size)

#define INVALIDATE_CACHE_UDELAY(map, chip, adr, len, usec)  \
	UDELAY(map, chip, adr, usec)

/*
 * Extra notes:
 *
 * Activating this XIP support changes the way the code works a bit.  For
 * example the code to suspend the current process when concurrent access
 * happens is never executed because xip_udelay() will always return with the
 * same chip state as it was entered with.  This is why there is no care for
 * the presence of add_wait_queue() or schedule() calls from within a couple
 * xip_disable()'d  areas of code, like in do_erase_oneblock for example.
 * The queueing and scheduling are always happening within xip_udelay().
 *
 * Similarly, get_chip() and put_chip() just happen to always be executed
 * with chip->state set to FL_READY (or FL_XIP_WHILE_*) where flash state
 * is in array mode, therefore never executing many cases therein and not
 * causing any problem with XIP.
 */

#else

#define xip_disable(map, chip, adr)
#define xip_enable(map, chip, adr)
#define XIP_INVAL_CACHED_RANGE(x...)

#define UDELAY(map, chip, adr, usec)  \
do {  \
	spin_unlock(chip->mutex);  \
	cfi_udelay(usec);  \
	spin_lock(chip->mutex);  \
} while (0)

#define INVALIDATE_CACHE_UDELAY(map, chip, adr, len, usec)  \
do {  \
	spin_unlock(chip->mutex);  \
	INVALIDATE_CACHED_RANGE(map, adr, len);  \
	cfi_udelay(usec);  \
	spin_lock(chip->mutex);  \
} while (0)

#endif

static inline int do_read_onechip(struct map_info *map, struct flchip *chip, loff_t adr, size_t len, u_char *buf)
{
	unsigned long cmd_addr;
	struct cfi_private *cfi = map->fldrv_priv;
	int ret;

	adr += chip->start;

	/* Ensure cmd read/writes are aligned. */
	cmd_addr = adr & ~(map_bankwidth(map)-1);

	spin_lock(chip->mutex);
	ret = get_chip(map, chip, cmd_addr, FL_READY);
	if (ret) {
		spin_unlock(chip->mutex);
		return ret;
	}

	if (chip->state != FL_POINT && chip->state != FL_READY) {
		map_write(map, CMD(0xf0), cmd_addr);
		chip->state = FL_READY;
	}

	map_copy_from(map, buf, adr, len);

	put_chip(map, chip, cmd_addr);

	spin_unlock(chip->mutex);
	return 0;
}


static int cfi_amdstd_read (struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf)
{
	struct map_info *map = mtd->priv;
	struct cfi_private *cfi = map->fldrv_priv;
	unsigned long ofs;
	int chipnum;
	int ret = 0;

	/* ofs: offset within the first chip that the first read should start */

	chipnum = (from >> cfi->chipshift);
	ofs = from - (chipnum <<  cfi->chipshift);


	*retlen = 0;

	while (len) {
		unsigned long thislen;

		if (chipnum >= cfi->numchips)
			break;

		if ((len + ofs -1) >> cfi->chipshift)
			thislen = (1<<cfi->chipshift) - ofs;
		else
			thislen = len;

		ret = do_read_onechip(map, &cfi->chips[chipnum], ofs, thislen, buf);
		if (ret)
			break;

		*retlen += thislen;
		len -= thislen;
		buf += thislen;

		ofs = 0;
		chipnum++;
	}
	return ret;
}


static inline int do_read_secsi_onechip(struct map_info *map, struct flchip *chip, loff_t adr, size_t len, u_char *buf)
{
	DECLARE_WAITQUEUE(wait, current);
	unsigned long timeo = jiffies + HZ;
	struct cfi_private *cfi = map->fldrv_priv;

 retry:
	spin_lock(chip->mutex);

	if (chip->state != FL_READY){
#if 0
		printk(KERN_DEBUG "Waiting for chip to read, status = %d\n", chip->state);
#endif
		set_current_state(TASK_UNINTERRUPTIBLE);
		add_wait_queue(&chip->wq, &wait);

		spin_unlock(chip->mutex);

		schedule();
		remove_wait_queue(&chip->wq, &wait);
#if 0
		if(signal_pending(current))
			return -EINTR;
#endif
		timeo = jiffies + HZ;

		goto retry;
	}

	adr += chip->start;

	chip->state = FL_READY;

	cfi_send_gen_cmd(0xAA, cfi->addr_unlock1, chip->start, map, cfi, cfi->device_type, NULL);
	cfi_send_gen_cmd(0x55, cfi->addr_unlock2, chip->start, map, cfi, cfi->device_type, NULL);
	cfi_send_gen_cmd(0x88, cfi->addr_unlock1, chip->start, map, cfi, cfi->device_type, NULL);

	map_copy_from(map, buf, adr, len);

	cfi_send_gen_cmd(0xAA, cfi->addr_unlock1, chip->start, map, cfi, cfi->device_type, NULL);
	cfi_send_gen_cmd(0x55, cfi->addr_unlock2, chip->start, map, cfi, cfi->device_type, NULL);
	cfi_send_gen_cmd(0x90, cfi->addr_unlock1, chip->start, map, cfi, cfi->device_type, NULL);
	cfi_send_gen_cmd(0x00, cfi->addr_unlock1, chip->start, map, cfi, cfi->device_type, NULL);

	wake_up(&chip->wq);
	spin_unlock(chip->mutex);

	return 0;
}

static int cfi_amdstd_secsi_read (struct mtd_info *mtd, loff_t from, size_t len, size_t *retlen, u_char *buf)
{
	struct map_info *map = mtd->priv;
	struct cfi_private *cfi = map->fldrv_priv;
	unsigned long ofs;
	int chipnum;
	int ret = 0;


	/* ofs: offset within the first chip that the first read should start */

	/* 8 secsi bytes per chip */
	chipnum=from>>3;
	ofs=from & 7;


	*retlen = 0;

	while (len) {
		unsigned long thislen;

		if (chipnum >= cfi->numchips)
			break;

		if ((len + ofs -1) >> 3)
			thislen = (1<<3) - ofs;
		else
			thislen = len;

		ret = do_read_secsi_onechip(map, &cfi->chips[chipnum], ofs, thislen, buf);
		if (ret)
			break;

		*retlen += thislen;
		len -= thislen;
		buf += thislen;

		ofs = 0;
		chipnum++;
	}
	return ret;
}


static int __xipram do_write_oneword(struct map_info *map, struct flchip *chip, unsigned long adr, map_word datum)
{
	struct cfi_private *cfi = map->fldrv_priv;
	unsigned long timeo = jiffies + HZ;
	/*
	 * We use a 1ms + 1 jiffies generic timeout for writes (most devices
	 * have a max write time of a few hundreds usec). However, we should
	 * use the maximum timeout value given by the chip at probe time
	 * instead.  Unfortunately, struct flchip does have a field for
	 * maximum timeout, only for typical which can be far too short
	 * depending of the conditions.	 The ' + 1' is to avoid having a
	 * timeout of 0 jiffies if HZ is smaller than 1000.
	 */
	unsigned long uWriteTimeout = ( HZ / 1000 ) + 1;
	int ret = 0;
	map_word oldd;
	int retry_cnt = 0;

	adr += chip->start;

	spin_lock(chip->mutex);
	ret = get_chip(map, chip, adr, FL_WRITING);
	if (ret) {
		spin_unlock(chip->mutex);
		return ret;
	}

	DEBUG( MTD_DEBUG_LEVEL3, "MTD %s(): WRITE 0x%.8lx(0x%.8lx)\n",
	       __func__, adr, datum.x[0] );

	/*
	 * Check for a NOP for the case when the datum to write is already
	 * present - it saves time and works around buggy chips that corrupt
	 * data at other locations when 0xff is written to a location that
	 * already contains 0xff.
	 */
	oldd = map_read(map, adr);
	if (map_word_equal(map, oldd, datum)) {
		DEBUG( MTD_DEBUG_LEVEL3, "MTD %s(): NOP\n",
		       __func__);
		goto op_done;
	}

	XIP_INVAL_CACHED_RANGE(map, adr, map_bankwidth(map));
	ENABLE_VPP(map);
	xip_disable(map, chip, adr);
 retry:
	cfi_send_gen_cmd(0xAA, cfi->addr_unlock1, chip->start, map, cfi, cfi->device_type, NULL);
	cfi_send_gen_cmd(0x55, cfi->addr_unlock2, chip->start, map, cfi, cfi->device_type, NULL);
	cfi_send_gen_cmd(0xA0, cfi->addr_unlock1, chip->start, map, cfi, cfi->device_type, NULL);
	map_write(map, datum, adr);
	chip->state = FL_WRITING;

	INVALIDATE_CACHE_UDELAY(map, chip,
				adr, map_bankwidth(map),
				chip->word_write_time);

	/* See comment above for timeout value. */
	timeo = jiffies + uWriteTimeout;
	for (;;) {
		if (chip->state != FL_WRITING) {
			/* Someone's suspended the write. Sleep */
			DECLARE_WAITQUEUE(wait, current);

			set_current_state(TASK_UNINTERRUPTIBLE);
			add_wait_queue(&chip->wq, &wait);
			spin_unlock(chip->mutex);
			schedule();
			remove_wait_queue(&chip->wq, &wait);
			timeo = jiffies + (HZ / 2); /* FIXME */
			spin_lock(chip->mutex);
			continue;
		}

		if (time_after(jiffies, timeo) && !chip_ready(map, adr)){
			xip_enable(map, chip, adr);
			printk(KERN_WARNING "MTD %s(): software timeout\n", __func__);
			xip_disable(map, chip, adr);
			break;
		}

		if (chip_ready(map, adr))
			break;

		/* Latency issues. Drop the lock, wait a while and retry */
		UDELAY(map, chip, adr, 1);
	}
	/* Did we succeed? */
	if (!chip_good(map, adr, datum)) {
		/* reset on all failures. */
		map_write( map, CMD(0xF0), chip->start );
		/* FIXME - should have reset delay before continuing */

		if (++retry_cnt <= MAX_WORD_RETRIES)
			goto retry;

		ret = -EIO;
	}
	xip_enable(map, chip, adr);
 op_done:
	chip->state = FL_READY;
	put_chip(map, chip, adr);
	spin_unlock(chip->mutex);

	return ret;
}


static int cfi_amdstd_write_words(struct mtd_info *mtd, loff_t to, size_t len,
				  size_t *retlen, const u_char *buf)
{
	struct map_info *map = mtd->priv;
	struct cfi_private *cfi = map->fldrv_priv;
	int ret = 0;
	int chipnum;
	unsigned long ofs, chipstart;
	DECLARE_WAITQUEUE(wait, current);

	*retlen = 0;
	if (!len)
		return 0;

	chipnum = to >> cfi->chipshift;
	ofs = to  - (chipnum << cfi->chipshift);
	chipstart = cfi->chips[chipnum].start;

	/* If it's not bus-aligned, do the first byte write */
	if (ofs & (map_bankwidth(map)-1)) {
		unsigned long bus_ofs = ofs & ~(map_bankwidth(map)-1);
		int i = ofs - bus_ofs;
		int n = 0;
		map_word tmp_buf;

 retry:
		spin_lock(cfi->chips[chipnum].mutex);

		if (cfi->chips[chipnum].state != FL_READY) {
#if 0
			printk(KERN_DEBUG "Waiting for chip to write, status = %d\n", cfi->chips[chipnum].state);
#endif
			set_current_state(TASK_UNINTERRUPTIBLE);
			add_wait_queue(&cfi->chips[chipnum].wq, &wait);

			spin_unlock(cfi->chips[chipnum].mutex);

			schedule();
			remove_wait_queue(&cfi->chips[chipnum].wq, &wait);
#if 0
			if(signal_pending(current))
				return -EINTR;
#endif
			goto retry;
		}

		/* Load 'tmp_buf' with old contents of flash */
		tmp_buf = map_read(map, bus_ofs+chipstart);

		spin_unlock(cfi->chips[chipnum].mutex);

		/* Number of bytes to copy from buffer */
		n = min_t(int, len, map_bankwidth(map)-i);

		tmp_buf = map_word_load_partial(map, tmp_buf, buf, i, n);

		ret = do_write_oneword(map, &cfi->chips[chipnum],
				       bus_ofs, tmp_buf);
		if (ret)
			return ret;

		ofs += n;
		buf += n;
		(*retlen) += n;
		len -= n;

		if (ofs >> cfi->chipshift) {
			chipnum ++;
			ofs = 0;
			if (chipnum == cfi->numchips)
				return 0;
		}
	}

	/* We are now aligned, write as much as possible */
	while(len >= map_bankwidth(map)) {
		map_word datum;

		datum = map_word_load(map, buf);

		ret = do_write_oneword(map, &cfi->chips[chipnum],
				       ofs, datum);
		if (ret)
			return ret;

		ofs += map_bankwidth(map);
		buf += map_bankwidth(map);
		(*retlen) += map_bankwidth(map);
		len -= map_bankwidth(map);

		if (ofs >> cfi->chipshift) {
			chipnum ++;
			ofs = 0;
			if (chipnum == cfi->numchips)
				return 0;
			chipstart = cfi->chips[chipnum].start;
		}
	}

	/* Write the trailing bytes if any */
	if (len & (map_bankwidth(map)-1)) {
		map_word tmp_buf;

 retry1:
		spin_lock(cfi->chips[chipnum].mutex);

		if (cfi->chips[chipnum].state != FL_READY) {
#if 0
			printk(KERN_DEBUG "Waiting for chip to write, status = %d\n", cfi->chips[chipnum].state);
#endif
			set_current_state(TASK_UNINTERRUPTIBLE);
			add_wait_queue(&cfi->chips[chipnum].wq, &wait);

			spin_unlock(cfi->chips[chipnum].mutex);

			schedule();
			remove_wait_queue(&cfi->chips[chipnum].wq, &wait);
#if 0
			if(signal_pending(current))
				return -EINTR;
#endif
			goto retry1;
		}

		tmp_buf = map_read(map, ofs + chipstart);

		spin_unlock(cfi->chips[chipnum].mutex);

		tmp_buf = map_word_load_partial(map, tmp_buf, buf, 0, len);

		ret = do_write_oneword(map, &cfi->chips[chipnum],
				ofs, tmp_buf);
		if (ret)
			return ret;

		(*retlen) += len;
	}

	return 0;
}


/*
 * FIXME: interleaved mode not tested, and probably not supported!
 */
static int __xipram do_write_buffer(struct map_info *map, struct flchip *chip,
				    unsigned long adr, const u_char *buf,
				    int len)
{
	struct cfi_private *cfi = map->fldrv_priv;
	unsigned long timeo = jiffies + HZ;
	/* see comments in do_write_oneword() regarding uWriteTimeo. */
	unsigned long uWriteTimeout = ( HZ / 1000 ) + 1;
	int ret = -EIO;
	unsigned long cmd_adr;
	int z, words;
	map_word datum;

	adr += chip->start;
	cmd_adr = adr;

	spin_lock(chip->mutex);
	ret = get_chip(map, chip, adr, FL_WRITING);
	if (ret) {
		spin_unlock(chip->mutex);
		return ret;
	}

	datum = map_word_load(map, buf);

	DEBUG( MTD_DEBUG_LEVEL3, "MTD %s(): WRITE 0x%.8lx(0x%.8lx)\n",
	       __func__, adr, datum.x[0] );

	XIP_INVAL_CACHED_RANGE(map, adr, len);
	ENABLE_VPP(map);
	xip_disable(map, chip, cmd_adr);

	cfi_send_gen_cmd(0xAA, cfi->addr_unlock1, chip->start, map, cfi, cfi->device_type, NULL);
	cfi_send_gen_cmd(0x55, cfi->addr_unlock2, chip->start, map, cfi, cfi->device_type, NULL);
	//cfi_send_gen_cmd(0xA0, cfi->addr_unlock1, chip->start, map, cfi, cfi->device_type, NULL);

	/* Write Buffer Load */
	map_write(map, CMD(0x25), cmd_adr);

	chip->state = FL_WRITING_TO_BUFFER;

	/* Write length of data to come */
	words = len / map_bankwidth(map);
	map_write(map, CMD(words - 1), cmd_adr);
	/* Write data */
	z = 0;
	while(z < words * map_bankwidth(map)) {
		datum = map_word_load(map, buf);
		map_write(map, datum, adr + z);

		z += map_bankwidth(map);
		buf += map_bankwidth(map);
	}
	z -= map_bankwidth(map);

	adr += z;

	/* Write Buffer Program Confirm: GO GO GO */
	map_write(map, CMD(0x29), cmd_adr);
	chip->state = FL_WRITING;

	INVALIDATE_CACHE_UDELAY(map, chip,
				adr, map_bankwidth(map),
				chip->word_write_time);

	timeo = jiffies + uWriteTimeout;

	for (;;) {
		if (chip->state != FL_WRITING) {
			/* Someone's suspended the write. Sleep */
			DECLARE_WAITQUEUE(wait, current);

			set_current_state(TASK_UNINTERRUPTIBLE);
			add_wait_queue(&chip->wq, &wait);
			spin_unlock(chip->mutex);
			schedule();
			remove_wait_queue(&chip->wq, &wait);
			timeo = jiffies + (HZ / 2); /* FIXME */
			spin_lock(chip->mutex);
			continue;
		}

		if (time_after(jiffies, timeo) && !chip_ready(map, adr))
			break;

		if (chip_ready(map, adr)) {
			xip_enable(map, chip, adr);
			goto op_done;
		}

		/* Latency issues. Drop the lock, wait a while and retry */
		UDELAY(map, chip, adr, 1);
	}

	/* reset on all failures. */
	map_write( map, CMD(0xF0), chip->start );
	xip_enable(map, chip, adr);
	/* FIXME - should have reset delay before continuing */

	printk(KERN_WARNING "MTD %s(): software timeout\n",
	       __func__ );

	ret = -EIO;
 op_done:
	chip->state = FL_READY;
	put_chip(map, chip, adr);
	spin_unlock(chip->mutex);

	return ret;
}


static int cfi_amdstd_write_buffers(struct mtd_info *mtd, loff_t to, size_t len,
				    size_t *retlen, const u_char *buf)
{
	struct map_info *map = mtd->priv;
	struct cfi_private *cfi = map->fldrv_priv;
	int wbufsize = cfi_interleave(cfi) << cfi->cfiq->MaxBufWriteSize;
	int ret = 0;
	int chipnum;
	unsigned long ofs;

	*retlen = 0;
	if (!len)
		return 0;

	chipnum = to >> cfi->chipshift;
	ofs = to  - (chipnum << cfi->chipshift);

	/* If it's not bus-aligned, do the first word write */
	if (ofs & (map_bankwidth(map)-1)) {
		size_t local_len = (-ofs)&(map_bankwidth(map)-1);
		if (local_len > len)
			local_len = len;
		ret = cfi_amdstd_write_words(mtd, ofs + (chipnum<<cfi->chipshift),
					     local_len, retlen, buf);
		if (ret)
			return ret;
		ofs += local_len;
		buf += local_len;
		len -= local_len;

		if (ofs >> cfi->chipshift) {
			chipnum ++;
			ofs = 0;
			if (chipnum == cfi->numchips)
				return 0;
		}
	}

	/* Write buffer is worth it only if more than one word to write... */
	while (len >= map_bankwidth(map) * 2) {
		/* We must not cross write block boundaries */
		int size = wbufsize - (ofs & (wbufsize-1));

		if (size > len)
			size = len;
		if (size % map_bankwidth(map))
			size -= size % map_bankwidth(map);

		ret = do_write_buffer(map, &cfi->chips[chipnum],
				      ofs, buf, size);
		if (ret)
			return ret;

		ofs += size;
		buf += size;
		(*retlen) += size;
		len -= size;

		if (ofs >> cfi->chipshift) {
			chipnum ++;
			ofs = 0;
			if (chipnum == cfi->numchips)
				return 0;
		}
	}

	if (len) {
		size_t retlen_dregs = 0;

		ret = cfi_amdstd_write_words(mtd, ofs + (chipnum<<cfi->chipshift),
					     len, &retlen_dregs, buf);

		*retlen += retlen_dregs;
		return ret;
	}

	return 0;
}


/*
 * Handle devices with one erase region, that only implement
 * the chip erase command.
 */
static int __xipram do_erase_chip(struct map_info *map, struct flchip *chip)
{
	struct cfi_private *cfi = map->fldrv_priv;
	unsigned long timeo = jiffies + HZ;
	unsigned long int adr;
	DECLARE_WAITQUEUE(wait, current);
	int ret = 0;

	adr = cfi->addr_unlock1;

	spin_lock(chip->mutex);
	ret = get_chip(map, chip, adr, FL_WRITING);
	if (ret) {
		spin_unlock(chip->mutex);
		return ret;
	}

	DEBUG( MTD_DEBUG_LEVEL3, "MTD %s(): ERASE 0x%.8lx\n",
	       __func__, chip->start );

	XIP_INVAL_CACHED_RANGE(map, adr, map->size);
	ENABLE_VPP(map);
	xip_disable(map, chip, adr);

	cfi_send_gen_cmd(0xAA, cfi->addr_unlock1, chip->start, map, cfi, cfi->device_type, NULL);
	cfi_send_gen_cmd(0x55, cfi->addr_unlock2, chip->start, map, cfi, cfi->device_type, NULL);
	cfi_send_gen_cmd(0x80, cfi->addr_unlock1, chip->start, map, cfi, cfi->device_type, NULL);
	cfi_send_gen_cmd(0xAA, cfi->addr_unlock1, chip->start, map, cfi, cfi->device_type, NULL);
	cfi_send_gen_cmd(0x55, cfi->addr_unlock2, chip->start, map, cfi, cfi->device_type, NULL);
	cfi_send_gen_cmd(0x10, cfi->addr_unlock1, chip->start, map, cfi, cfi->device_type, NULL);

	chip->state = FL_ERASING;
	chip->erase_suspended = 0;
	chip->in_progress_block_addr = adr;

	INVALIDATE_CACHE_UDELAY(map, chip,
				adr, map->size,
				chip->erase_time*500);

	timeo = jiffies + (HZ*20);

	for (;;) {
		if (chip->state != FL_ERASING) {
			/* Someone's suspended the erase. Sleep */
			set_current_state(TASK_UNINTERRUPTIBLE);
			add_wait_queue(&chip->wq, &wait);
			spin_unlock(chip->mutex);
			schedule();
			remove_wait_queue(&chip->wq, &wait);
			spin_lock(chip->mutex);
			continue;
		}
		if (chip->erase_suspended) {
			/* This erase was suspended and resumed.
			   Adjust the timeout */
			timeo = jiffies + (HZ*20); /* FIXME */
			chip->erase_suspended = 0;
		}

		if (chip_ready(map, adr))
			break;

		if (time_after(jiffies, timeo)) {
			printk(KERN_WARNING "MTD %s(): software timeout\n",
				__func__ );
			break;
		}

		/* Latency issues. Drop the lock, wait a while and retry */
		UDELAY(map, chip, adr, 1000000/HZ);
	}
	/* Did we succeed? */
	if (!chip_good(map, adr, map_word_ff(map))) {
		/* reset on all failures. */
		map_write( map, CMD(0xF0), chip->start );
		/* FIXME - should have reset delay before continuing */

		ret = -EIO;
	}

	chip->state = FL_READY;
	xip_enable(map, chip, adr);
	put_chip(map, chip, adr);
	spin_unlock(chip->mutex);

	return ret;
}


static int __xipram do_erase_oneblock(struct map_info *map, struct flchip *chip, unsigned long adr, int len, void *thunk)
{
	struct cfi_private *cfi = map->fldrv_priv;
	unsigned long timeo = jiffies + HZ;
	DECLARE_WAITQUEUE(wait, current);
	int ret = 0;

	adr += chip->start;

	spin_lock(chip->mutex);
	ret = get_chip(map, chip, adr, FL_ERASING);
	if (ret) {
		spin_unlock(chip->mutex);
		return ret;
	}

	DEBUG( MTD_DEBUG_LEVEL3, "MTD %s(): ERASE 0x%.8lx\n",
	       __func__, adr );

	XIP_INVAL_CACHED_RANGE(map, adr, len);
	ENABLE_VPP(map);
	xip_disable(map, chip, adr);

	cfi_send_gen_cmd(0xAA, cfi->addr_unlock1, chip->start, map, cfi, cfi->device_type, NULL);
	cfi_send_gen_cmd(0x55, cfi->addr_unlock2, chip->start, map, cfi, cfi->device_type, NULL);
	cfi_send_gen_cmd(0x80, cfi->addr_unlock1, chip->start, map, cfi, cfi->device_type, NULL);
	cfi_send_gen_cmd(0xAA, cfi->addr_unlock1, chip->start, map, cfi, cfi->device_type, NULL);
	cfi_send_gen_cmd(0x55, cfi->addr_unlock2, chip->start, map, cfi, cfi->device_type, NULL);
	map_write(map, CMD(0x30), adr);

	chip->state = FL_ERASING;
	chip->erase_suspended = 0;
	chip->in_progress_block_addr = adr;

	INVALIDATE_CACHE_UDELAY(map, chip,
				adr, len,
				chip->erase_time*500);

	timeo = jiffies + (HZ*20);

	for (;;) {
		if (chip->state != FL_ERASING) {
			/* Someone's suspended the erase. Sleep */
			set_current_state(TASK_UNINTERRUPTIBLE);
			add_wait_queue(&chip->wq, &wait);
			spin_unlock(chip->mutex);
			schedule();
			remove_wait_queue(&chip->wq, &wait);
			spin_lock(chip->mutex);
			continue;
		}
		if (chip->erase_suspended) {
			/* This erase was suspended and resumed.
			   Adjust the timeout */
			timeo = jiffies + (HZ*20); /* FIXME */
			chip->erase_suspended = 0;
		}

		if (chip_ready(map, adr)) {
			xip_enable(map, chip, adr);
			break;
		}

		if (time_after(jiffies, timeo)) {
			xip_enable(map, chip, adr);
			printk(KERN_WARNING "MTD %s(): software timeout\n",
				__func__ );
			break;
		}

		/* Latency issues. Drop the lock, wait a while and retry */
		UDELAY(map, chip, adr, 1000000/HZ);
	}
	/* Did we succeed? */
	if (!chip_good(map, adr, map_word_ff(map))) {
		/* reset on all failures. */
		map_write( map, CMD(0xF0), chip->start );
		/* FIXME - should have reset delay before continuing */

		ret = -EIO;
	}

	chip->state = FL_READY;
	put_chip(map, chip, adr);
	spin_unlock(chip->mutex);
	return ret;
}


static int cfi_amdstd_erase_varsize(struct mtd_info *mtd, struct erase_info *instr)
{
	unsigned long ofs, len;
	int ret;

	ofs = instr->addr;
	len = instr->len;

	ret = cfi_varsize_frob(mtd, do_erase_oneblock, ofs, len, NULL);
	if (ret)
		return ret;

	instr->state = MTD_ERASE_DONE;
	mtd_erase_callback(instr);

	return 0;
}


static int cfi_amdstd_erase_chip(struct mtd_info *mtd, struct erase_info *instr)
{
	struct map_info *map = mtd->priv;
	struct cfi_private *cfi = map->fldrv_priv;
	int ret = 0;

	if (instr->addr != 0)
		return -EINVAL;

	if (instr->len != mtd->size)
		return -EINVAL;

	ret = do_erase_chip(map, &cfi->chips[0]);
	if (ret)
		return ret;

	instr->state = MTD_ERASE_DONE;
	mtd_erase_callback(instr);

	return 0;
}

static int do_atmel_lock(struct map_info *map, struct flchip *chip,
			 unsigned long adr, int len, void *thunk)
{
	struct cfi_private *cfi = map->fldrv_priv;
	int ret;

	spin_lock(chip->mutex);
	ret = get_chip(map, chip, adr + chip->start, FL_LOCKING);
	if (ret)
		goto out_unlock;
	chip->state = FL_LOCKING;

	DEBUG(MTD_DEBUG_LEVEL3, "MTD %s(): LOCK 0x%08lx len %d\n",
	      __func__, adr, len);

	cfi_send_gen_cmd(0xAA, cfi->addr_unlock1, chip->start, map, cfi,
			 cfi->device_type, NULL);
	cfi_send_gen_cmd(0x55, cfi->addr_unlock2, chip->start, map, cfi,
			 cfi->device_type, NULL);
	cfi_send_gen_cmd(0x80, cfi->addr_unlock1, chip->start, map, cfi,
			 cfi->device_type, NULL);
	cfi_send_gen_cmd(0xAA, cfi->addr_unlock1, chip->start, map, cfi,
			 cfi->device_type, NULL);
	cfi_send_gen_cmd(0x55, cfi->addr_unlock2, chip->start, map, cfi,
			 cfi->device_type, NULL);
	map_write(map, CMD(0x40), chip->start + adr);

	chip->state = FL_READY;
	put_chip(map, chip, adr + chip->start);
	ret = 0;

out_unlock:
	spin_unlock(chip->mutex);
	return ret;
}

static int do_atmel_unlock(struct map_info *map, struct flchip *chip,
			   unsigned long adr, int len, void *thunk)
{
	struct cfi_private *cfi = map->fldrv_priv;
	int ret;

	spin_lock(chip->mutex);
	ret = get_chip(map, chip, adr + chip->start, FL_UNLOCKING);
	if (ret)
		goto out_unlock;
	chip->state = FL_UNLOCKING;

	DEBUG(MTD_DEBUG_LEVEL3, "MTD %s(): LOCK 0x%08lx len %d\n",
	      __func__, adr, len);

	cfi_send_gen_cmd(0xAA, cfi->addr_unlock1, chip->start, map, cfi,
			 cfi->device_type, NULL);
	map_write(map, CMD(0x70), adr);

	chip->state = FL_READY;
	put_chip(map, chip, adr + chip->start);
	ret = 0;

out_unlock:
	spin_unlock(chip->mutex);
	return ret;
}

static int cfi_atmel_lock(struct mtd_info *mtd, loff_t ofs, size_t len)
{
	return cfi_varsize_frob(mtd, do_atmel_lock, ofs, len, NULL);
}

static int cfi_atmel_unlock(struct mtd_info *mtd, loff_t ofs, size_t len)
{
	return cfi_varsize_frob(mtd, do_atmel_unlock, ofs, len, NULL);
}


static void cfi_amdstd_sync (struct mtd_info *mtd)
{
	struct map_info *map = mtd->priv;
	struct cfi_private *cfi = map->fldrv_priv;
	int i;
	struct flchip *chip;
	int ret = 0;
	DECLARE_WAITQUEUE(wait, current);

	for (i=0; !ret && i<cfi->numchips; i++) {
		chip = &cfi->chips[i];

	retry:
		spin_lock(chip->mutex);

		switch(chip->state) {
		case FL_READY:
		case FL_STATUS:
		case FL_CFI_QUERY:
		case FL_JEDEC_QUERY:
			chip->oldstate = chip->state;
			chip->state = FL_SYNCING;
			/* No need to wake_up() on this state change -
			 * as the whole point is that nobody can do anything
			 * with the chip now anyway.
			 */
		case FL_SYNCING:
			spin_unlock(chip->mutex);
			break;

		default:
			/* Not an idle state */
			set_current_state(TASK_UNINTERRUPTIBLE);
			add_wait_queue(&chip->wq, &wait);

			spin_unlock(chip->mutex);

			schedule();

			remove_wait_queue(&chip->wq, &wait);

			goto retry;
		}
	}

	/* Unlock the chips again */

	for (i--; i >=0; i--) {
		chip = &cfi->chips[i];

		spin_lock(chip->mutex);

		if (chip->state == FL_SYNCING) {
			chip->state = chip->oldstate;
			wake_up(&chip->wq);
		}
		spin_unlock(chip->mutex);
	}
}


static int cfi_amdstd_suspend(struct mtd_info *mtd)
{
	struct map_info *map = mtd->priv;
	struct cfi_private *cfi = map->fldrv_priv;
	int i;
	struct flchip *chip;
	int ret = 0;

	for (i=0; !ret && i<cfi->numchips; i++) {
		chip = &cfi->chips[i];

		spin_lock(chip->mutex);

		switch(chip->state) {
		case FL_READY:
		case FL_STATUS:
		case FL_CFI_QUERY:
		case FL_JEDEC_QUERY:
			chip->oldstate = chip->state;
			chip->state = FL_PM_SUSPENDED;
			/* No need to wake_up() on this state change -
			 * as the whole point is that nobody can do anything
			 * with the chip now anyway.
			 */
		case FL_PM_SUSPENDED:
			break;

		default:
			ret = -EAGAIN;
			break;
		}
		spin_unlock(chip->mutex);
	}

	/* Unlock the chips again */

	if (ret) {
		for (i--; i >=0; i--) {
			chip = &cfi->chips[i];

			spin_lock(chip->mutex);

			if (chip->state == FL_PM_SUSPENDED) {
				chip->state = chip->oldstate;
				wake_up(&chip->wq);
			}
			spin_unlock(chip->mutex);
		}
	}

	return ret;
}


static void cfi_amdstd_resume(struct mtd_info *mtd)
{
	struct map_info *map = mtd->priv;
	struct cfi_private *cfi = map->fldrv_priv;
	int i;
	struct flchip *chip;

	for (i=0; i<cfi->numchips; i++) {

		chip = &cfi->chips[i];

		spin_lock(chip->mutex);

		if (chip->state == FL_PM_SUSPENDED) {
			chip->state = FL_READY;
			map_write(map, CMD(0xF0), chip->start);
			wake_up(&chip->wq);
		}
		else
			printk(KERN_ERR "Argh. Chip not in PM_SUSPENDED state upon resume()\n");

		spin_unlock(chip->mutex);
	}
}

static void cfi_amdstd_destroy(struct mtd_info *mtd)
{
	struct map_info *map = mtd->priv;
	struct cfi_private *cfi = map->fldrv_priv;

	kfree(cfi->cmdset_priv);
	kfree(cfi->cfiq);
	kfree(cfi);
	kfree(mtd->eraseregions);
}

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Crossnet Co. <info@crossnet.co.jp> et al.");
MODULE_DESCRIPTION("MTD chip driver for AMD/Fujitsu flash chips");