/*
   Common Flash Interface probe code.
   (C) 2000 Red Hat. GPL'd.
*/

#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <asm/io.h>
#include <asm/byteorder.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/interrupt.h>

#include <linux/mtd/xip.h>
#include <linux/mtd/map.h>
#include <linux/mtd/cfi.h>
#include <linux/mtd/gen_probe.h>

//#define DEBUG_CFI

#ifdef DEBUG_CFI
static void print_cfi_ident(struct cfi_ident *);
#endif

static int cfi_probe_chip(struct map_info *map, __u32 base,
			  unsigned long *chip_map, struct cfi_private *cfi);
static int cfi_chip_setup(struct map_info *map, struct cfi_private *cfi);

struct mtd_info *cfi_probe(struct map_info *map);

#ifdef CONFIG_MTD_XIP

/* only needed for short periods, so this is rather simple */
#define xip_disable()	local_irq_disable()

#define xip_allowed(base, map) \
do { \
	(void) map_read(map, base); \
	xip_iprefetch(); \
	local_irq_enable(); \
} while (0)

#define xip_enable(base, map, cfi) \
do { \
	cfi_send_gen_cmd(0xF0, 0, base, map, cfi, cfi->device_type, NULL); \
	cfi_send_gen_cmd(0xFF, 0, base, map, cfi, cfi->device_type, NULL); \
	xip_allowed(base, map); \
} while (0)

#define xip_disable_qry(base, map, cfi) \
do { \
	xip_disable(); \
	cfi_send_gen_cmd(0xF0, 0, base, map, cfi, cfi->device_type, NULL); \
	cfi_send_gen_cmd(0xFF, 0, base, map, cfi, cfi->device_type, NULL); \
	cfi_send_gen_cmd(0x98, 0x55, base, map, cfi, cfi->device_type, NULL); \
} while (0)

#else

#define xip_disable()			do { } while (0)
#define xip_allowed(base, map)		do { } while (0)
#define xip_enable(base, map, cfi)	do { } while (0)
#define xip_disable_qry(base, map, cfi) do { } while (0)

#endif

/* check for QRY.
   in: interleave,type,mode
   ret: table index, <0 for error
 */
static int __xipram qry_present(struct map_info *map, __u32 base,
				struct cfi_private *cfi)
{
	int osf = cfi->interleave * cfi->device_type;	// scale factor
	map_word val[3];
	map_word qry[3];

	qry[0] = cfi_build_cmd('Q', map, cfi);
	qry[1] = cfi_build_cmd('R', map, cfi);
	qry[2] = cfi_build_cmd('Y', map, cfi);

	val[0] = map_read(map, base + osf*0x10);
	val[1] = map_read(map, base + osf*0x11);
	val[2] = map_read(map, base + osf*0x12);

	if (!map_word_equal(map, qry[0], val[0]))
		return 0;

	if (!map_word_equal(map, qry[1], val[1]))
		return 0;

	if (!map_word_equal(map, qry[2], val[2]))
		return 0;

	return 1; 	// "QRY" found
}

static int __xipram cfi_probe_chip(struct map_info *map, __u32 base,
				   unsigned long *chip_map, struct cfi_private *cfi)
{
	int i;

	if ((base + 0) >= map->size) {
		printk(KERN_NOTICE
			"Probe at base[0x00](0x%08lx) past the end of the map(0x%08lx)\n",
			(unsigned long)base, map->size -1);
		return 0;
	}
	if ((base + 0xff) >= map->size) {
		printk(KERN_NOTICE
			"Probe at base[0x55](0x%08lx) past the end of the map(0x%08lx)\n",
			(unsigned long)base + 0x55, map->size -1);
		return 0;
	}

	xip_disable();
	cfi_send_gen_cmd(0xF0, 0, base, map, cfi, cfi->device_type, NULL);
	cfi_send_gen_cmd(0xFF, 0, base, map, cfi, cfi->device_type, NULL);
	cfi_send_gen_cmd(0x98, 0x55, base, map, cfi, cfi->device_type, NULL);

	if (!qry_present(map,base,cfi)) {
		xip_enable(base, map, cfi);
		return 0;
	}

	if (!cfi->numchips) {
		/* This is the first time we're called. Set up the CFI
		   stuff accordingly and return */
		return cfi_chip_setup(map, cfi);
	}

	/* Check each previous chip to see if it's an alias */
 	for (i=0; i < (base >> cfi->chipshift); i++) {
 		unsigned long start;
 		if(!test_bit(i, chip_map)) {
			/* Skip location; no valid chip at this address */
 			continue;
 		}
 		start = i << cfi->chipshift;
		/* This chip should be in read mode if it's one
		   we've already touched. */
		if (qry_present(map, start, cfi)) {
			/* Eep. This chip also had the QRY marker.
			 * Is it an alias for the new one? */
			cfi_send_gen_cmd(0xF0, 0, start, map, cfi, cfi->device_type, NULL);
			cfi_send_gen_cmd(0xFF, 0, start, map, cfi, cfi->device_type, NULL);

			/* If the QRY marker goes away, it's an alias */
			if (!qry_present(map, start, cfi)) {
				xip_allowed(base, map);
				printk(KERN_DEBUG "%s: Found an alias at 0x%x for the chip at 0x%lx\n",
				       map->name, base, start);
				return 0;
			}
			/* Yes, it's actually got QRY for data. Most
			 * unfortunate. Stick the new chip in read mode
			 * too and if it's the same, assume it's an alias. */
			/* FIXME: Use other modes to do a proper check */
			cfi_send_gen_cmd(0xF0, 0, base, map, cfi, cfi->device_type, NULL);
			cfi_send_gen_cmd(0xFF, 0, start, map, cfi, cfi->device_type, NULL);

			if (qry_present(map, base, cfi)) {
				xip_allowed(base, map);
				printk(KERN_DEBUG "%s: Found an alias at 0x%x for the chip at 0x%lx\n",
				       map->name, base, start);
				return 0;
			}
		}
	}

	/* OK, if we got to here, then none of the previous chips appear to
	   be aliases for the current one. */
	set_bit((base >> cfi->chipshift), chip_map); /* Update chip map */
	cfi->numchips++;

	/* Put it back into Read Mode */
	cfi_send_gen_cmd(0xF0, 0, base, map, cfi, cfi->device_type, NULL);
	cfi_send_gen_cmd(0xFF, 0, base, map, cfi, cfi->device_type, NULL);
	xip_allowed(base, map);

	printk(KERN_INFO "%s: Found %d x%d devices at 0x%x in %d-bit bank\n",
	       map->name, cfi->interleave, cfi->device_type*8, base,
	       map->bankwidth*8);

	return 1;
}

static int __xipram cfi_chip_setup(struct map_info *map,
				   struct cfi_private *cfi)
{
	int ofs_factor = cfi->interleave*cfi->device_type;
	__u32 base = 0;
	int num_erase_regions = cfi_read_query(map, base + (0x10 + 28)*ofs_factor);
	int i;

	xip_enable(base, map, cfi);
#ifdef DEBUG_CFI
	printk("Number of erase regions: %d\n", num_erase_regions);
#endif
	if (!num_erase_regions)
		return 0;

	cfi->cfiq = kmalloc(sizeof(struct cfi_ident) + num_erase_regions * 4, GFP_KERNEL);
	if (!cfi->cfiq) {
		printk(KERN_WARNING "%s: kmalloc failed for CFI ident structure\n", map->name);
		return 0;
	}

	memset(cfi->cfiq,0,sizeof(struct cfi_ident));

	cfi->cfi_mode = CFI_MODE_CFI;

	/* Read the CFI info structure */
	xip_disable_qry(base, map, cfi);
	for (i=0; i<(sizeof(struct cfi_ident) + num_erase_regions * 4); i++)
		((unsigned char *)cfi->cfiq)[i] = cfi_read_query(map,base + (0x10 + i)*ofs_factor);

	/* Note we put the device back into Read Mode BEFORE going into Auto
	 * Select Mode, as some devices support nesting of modes, others
	 * don't. This way should always work.
	 * On cmdset 0001 the writes of 0xaa and 0x55 are not needed, and
	 * so should be treated as nops or illegal (and so put the device
	 * back into Read Mode, which is a nop in this case).
	 */
	cfi_send_gen_cmd(0xf0,     0, base, map, cfi, cfi->device_type, NULL);
	cfi_send_gen_cmd(0xaa, 0x555, base, map, cfi, cfi->device_type, NULL);
	cfi_send_gen_cmd(0x55, 0x2aa, base, map, cfi, cfi->device_type, NULL);
	cfi_send_gen_cmd(0x90, 0x555, base, map, cfi, cfi->device_type, NULL);
	cfi->mfr = cfi_read_query16(map, base);
	cfi->id = cfi_read_query16(map, base + ofs_factor);

	/* Get AMD/Spansion extended JEDEC ID */
	if (cfi->mfr == CFI_MFR_AMD && (cfi->id & 0xff) == 0x7e)
		cfi->id = cfi_read_query(map, base + 0xe * ofs_factor) << 8 |
			  cfi_read_query(map, base + 0xf * ofs_factor);

	/* Put it back into Read Mode */
	cfi_send_gen_cmd(0xF0, 0, base, map, cfi, cfi->device_type, NULL);
	/* ... even if it's an Intel chip */
	cfi_send_gen_cmd(0xFF, 0, base, map, cfi, cfi->device_type, NULL);
	xip_allowed(base, map);

	/* Do any necessary byteswapping */
	cfi->cfiq->P_ID = le16_to_cpu(cfi->cfiq->P_ID);

	cfi->cfiq->P_ADR = le16_to_cpu(cfi->cfiq->P_ADR);
	cfi->cfiq->A_ID = le16_to_cpu(cfi->cfiq->A_ID);
	cfi->cfiq->A_ADR = le16_to_cpu(cfi->cfiq->A_ADR);
	cfi->cfiq->InterfaceDesc = le16_to_cpu(cfi->cfiq->InterfaceDesc);
	cfi->cfiq->MaxBufWriteSize = le16_to_cpu(cfi->cfiq->MaxBufWriteSize);

#ifdef DEBUG_CFI
	/* Dump the information therein */
	print_cfi_ident(cfi->cfiq);
#endif

	for (i=0; i<cfi->cfiq->NumEraseRegions; i++) {
		cfi->cfiq->EraseRegionInfo[i] = le32_to_cpu(cfi->cfiq->EraseRegionInfo[i]);

#ifdef DEBUG_CFI
		printk("  Erase Region #%d: BlockSize 0x%4.4X bytes, %d blocks\n",
		       i, (cfi->cfiq->EraseRegionInfo[i] >> 8) & ~0xff,
		       (cfi->cfiq->EraseRegionInfo[i] & 0xffff) + 1);
#endif
	}

	printk(KERN_INFO "%s: Found %d x%d devices at 0x%x in %d-bit bank\n",
	       map->name, cfi->interleave, cfi->device_type*8, base,
	       map->bankwidth*8);

	return 1;
}

#ifdef DEBUG_CFI
static char *vendorname(__u16 vendor)
{
	switch (vendor) {
	case P_ID_NONE:
		return "None";

	case P_ID_INTEL_EXT:
		return "Intel/Sharp Extended";

	case P_ID_AMD_STD:
		return "AMD/Fujitsu Standard";

	case P_ID_INTEL_STD:
		return "Intel/Sharp Standard";

	case P_ID_AMD_EXT:
		return "AMD/Fujitsu Extended";

	case P_ID_WINBOND:
		return "Winbond Standard";

	case P_ID_ST_ADV:
		return "ST Advanced";

	case P_ID_MITSUBISHI_STD:
		return "Mitsubishi Standard";

	case P_ID_MITSUBISHI_EXT:
		return "Mitsubishi Extended";

	case P_ID_SST_PAGE:
		return "SST Page Write";

	case P_ID_INTEL_PERFORMANCE:
		return "Intel Performance Code";

	case P_ID_INTEL_DATA:
		return "Intel Data";

	case P_ID_RESERVED:
		return "Not Allowed / Reserved for Future Use";

	default:
		return "Unknown";
	}
}


static void print_cfi_ident(struct cfi_ident *cfip)
{
#if 0
	if (cfip->qry[0] != 'Q' || cfip->qry[1] != 'R' || cfip->qry[2] != 'Y') {
		printk("Invalid CFI ident structure.\n");
		return;
	}
#endif
	printk("Primary Vendor Command Set: %4.4X (%s)\n", cfip->P_ID, vendorname(cfip->P_ID));
	if (cfip->P_ADR)
		printk("Primary Algorithm Table at %4.4X\n", cfip->P_ADR);
	else
		printk("No Primary Algorithm Table\n");

	printk("Alternative Vendor Command Set: %4.4X (%s)\n", cfip->A_ID, vendorname(cfip->A_ID));
	if (cfip->A_ADR)
		printk("Alternate Algorithm Table at %4.4X\n", cfip->A_ADR);
	else
		printk("No Alternate Algorithm Table\n");


	printk("Vcc Minimum: %2d.%d V\n", cfip->VccMin >> 4, cfip->VccMin & 0xf);
	printk("Vcc Maximum: %2d.%d V\n", cfip->VccMax >> 4, cfip->VccMax & 0xf);
	if (cfip->VppMin) {
		printk("Vpp Minimum: %2d.%d V\n", cfip->VppMin >> 4, cfip->VppMin & 0xf);
		printk("Vpp Maximum: %2d.%d V\n", cfip->VppMax >> 4, cfip->VppMax & 0xf);
	}
	else
		printk("No Vpp line\n");

	printk("Typical byte/word write timeout: %d µs\n", 1<<cfip->WordWriteTimeoutTyp);
	printk("Maximum byte/word write timeout: %d µs\n", (1<<cfip->WordWriteTimeoutMax) * (1<<cfip->WordWriteTimeoutTyp));

	if (cfip->BufWriteTimeoutTyp || cfip->BufWriteTimeoutMax) {
		printk("Typical full buffer write timeout: %d µs\n", 1<<cfip->BufWriteTimeoutTyp);
		printk("Maximum full buffer write timeout: %d µs\n", (1<<cfip->BufWriteTimeoutMax) * (1<<cfip->BufWriteTimeoutTyp));
	}
	else
		printk("Full buffer write not supported\n");

	printk("Typical block erase timeout: %d ms\n", 1<<cfip->BlockEraseTimeoutTyp);
	printk("Maximum block erase timeout: %d ms\n", (1<<cfip->BlockEraseTimeoutMax) * (1<<cfip->BlockEraseTimeoutTyp));
	if (cfip->ChipEraseTimeoutTyp || cfip->ChipEraseTimeoutMax) {
		printk("Typical chip erase timeout: %d ms\n", 1<<cfip->ChipEraseTimeoutTyp);
		printk("Maximum chip erase timeout: %d ms\n", (1<<cfip->ChipEraseTimeoutMax) * (1<<cfip->ChipEraseTimeoutTyp));
	}
	else
		printk("Chip erase not supported\n");

	printk("Device size: 0x%X bytes (%d MiB)\n", 1 << cfip->DevSize, 1<< (cfip->DevSize - 20));
	printk("Flash Device Interface description: 0x%4.4X\n", cfip->InterfaceDesc);
	switch(cfip->InterfaceDesc) {
	case CFI_INTERFACE_X8_ASYNC:
		printk("  - x8-only asynchronous interface\n");
		break;

	case CFI_INTERFACE_X16_ASYNC:
		printk("  - x16-only asynchronous interface\n");
		break;

	case CFI_INTERFACE_X8_BY_X16_ASYNC:
		printk("  - supports x8 and x16 via BYTE# with asynchronous interface\n");
		break;

	case CFI_INTERFACE_X32_ASYNC:
		printk("  - x32-only asynchronous interface\n");
		break;

	case CFI_INTERFACE_X16_BY_X32_ASYNC:
		printk("  - supports x16 and x32 via Word# with asynchronous interface\n");
		break;

	case CFI_INTERFACE_NOT_ALLOWED:
		printk("  - Not Allowed / Reserved\n");
		break;

	default:
		printk("  - Unknown\n");
		break;
	}

	printk("Max. bytes in buffer write: 0x%x\n", 1<< cfip->MaxBufWriteSize);
	printk("Number of Erase Block Regions: %d\n", cfip->NumEraseRegions);

}
#endif /* DEBUG_CFI */

static struct chip_probe cfi_chip_probe = {
	.name		= "CFI",
	.probe_chip	= cfi_probe_chip
};

struct mtd_info *cfi_probe(struct map_info *map)
{
	/*
	 * Just use the generic probe stuff to call our CFI-specific
	 * chip_probe routine in all the possible permutations, etc.
	 */
	return mtd_do_chip_probe(map, &cfi_chip_probe);
}

static struct mtd_chip_driver cfi_chipdrv = {
	.probe		= cfi_probe,
	.name		= "cfi_probe",
	.module		= THIS_MODULE
};

static int __init cfi_probe_init(void)
{
	register_mtd_chip_driver(&cfi_chipdrv);
	return 0;
}

static void __exit cfi_probe_exit(void)
{
	unregister_mtd_chip_driver(&cfi_chipdrv);
}

module_init(cfi_probe_init);
module_exit(cfi_probe_exit);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org> et al.");
MODULE_DESCRIPTION("Probe code for CFI-compliant flash chips");