[PATCH][NAND] Add ssfdc read-only translation layer

[Claudio Lanconelli <lanconelli.claudio@eptar.com>]

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Hi,
here is another try.
Now it builds fine against git mtd-2.6, however I can't test if it works 
anymore after the changes,
my target system at the moment doesn't support kernel 2.6, sigh!

One question, I use major number 44 (since it's the number used by old 
ssfdc.c) but I don't
know if it's the correct number.

Signed-off-by: Claudio Lanconelli <lanconelli.claudio@eptar.com>

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diff --git a/drivers/mtd/nand/Kconfig b/drivers/mtd/nand/Kconfig
index 3db77ee..462c4ce 100644
--- a/drivers/mtd/nand/Kconfig
+++ b/drivers/mtd/nand/Kconfig
@@ -31,6 +31,22 @@ config MTD_NAND_ECC_SMC
 	  Software ECC according to the Smart Media Specification.
 	  The original Linux implementation had byte 0 and 1 swapped.
 
+config MTD_NAND_SSFDC_READONLY
+	bool "NAND SSFDC (SmartMedia) read only translation layer"
+	depends on MTD_NAND
+	default n
+	help
+	  This enable read only access to SmartMedia formatted Nand
+	  flash. You can mount it with FAT file system.
+
+config MTD_NAND_SSFDC_GETGEO
+	bool "Enable SmartMedia standard geometry CHS"
+	depends on MTD_NAND_SSFDC_READONLY
+	default n
+	help
+	  This forces the get geometry system call to return standard
+	  CHS values for SmartMedia.
+
 config MTD_NAND_AUTCPU12
 	tristate "SmartMediaCard on autronix autcpu12 board"
 	depends on MTD_NAND && ARCH_AUTCPU12
diff --git a/drivers/mtd/nand/Makefile b/drivers/mtd/nand/Makefile
index f747593..adee70e 100644
--- a/drivers/mtd/nand/Makefile
+++ b/drivers/mtd/nand/Makefile
@@ -22,5 +22,6 @@ obj-$(CONFIG_MTD_NAND_TS7250)		+= ts7250
 obj-$(CONFIG_MTD_NAND_NANDSIM)		+= nandsim.o
 obj-$(CONFIG_MTD_NAND_CS553X)		+= cs553x_nand.o
 obj-$(CONFIG_MTD_NAND_NDFC)		+= ndfc.o
+obj-$(CONFIG_MTD_NAND_SSFDC_READONLY)	+= ssfdc_ro.o
 
 nand-objs = nand_base.o nand_bbt.o
diff --git a/drivers/mtd/nand/ssfdc_ro.c b/drivers/mtd/nand/ssfdc_ro.c
new file mode 100644
index 0000000..30a16ea
--- /dev/null
+++ b/drivers/mtd/nand/ssfdc_ro.c
@@ -0,0 +1,484 @@
+/*
+ * Linux driver for SSFDC Flash Translation Layer (Read only)
+ * (c) 2005 Eptar srl
+ * Author: Claudio Lanconelli <lanconelli.claudio@eptar.com>
+ *
+ * Based on NTFL and MTDBLOCK_RO drivers
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/config.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/hdreg.h>
+#include <linux/mtd/mtd.h>
+#include <linux/mtd/nand.h>
+#include <linux/mtd/blktrans.h>
+
+/* #undef CONFIG_MTD_NAND_SSFDC_GETGEO */
+
+struct ssfdcr_record {
+	struct mtd_blktrans_dev mbd;
+	int usecount;
+#ifdef CONFIG_MTD_NAND_SSFDC_GETGEO
+	unsigned char heads;
+	unsigned char sectors;
+	unsigned short cylinders;
+#endif
+	int cis_block;			/* block n. containing CIS/IDI */
+	int erase_size;			/* phys_block_size */
+	unsigned short *logic_block_map; /* all zones (max 8192 phys blocks on
+					    the 128MB) */
+	int map_len;			/* n. phys_blocks on the card */
+};
+
+
+#define SSFDCR_MAJOR		44
+#define SSFDCR_PARTN_BITS	3
+
+#define SECTOR_SIZE		512
+#define SECTOR_SHIFT		9
+#define OOB_SIZE		16
+
+#define MAX_LOGIC_BLK_PER_ZONE	1000
+#define MAX_PHYS_BLK_PER_ZONE	1024
+
+#define KB(x)	( (x) * 1024L )
+#define MB(x)	( KB(x) * 1024L )
+
+/** CHS Table
+		1MB	2MB	4MB	8MB	16MB	32MB	64MB	128MB
+NCylinder	125	125	250	250	500	500	500	500
+NHead		4	4	4	4	4	8	8	16
+NSector		4	8	8	16	16	16	32	32
+SumSector	2,000	4,000	8,000	16,000	32,000	64,000	128,000	256,000
+SectorSize	512	512	512	512	512	512	512	512
+**/
+
+#ifdef CONFIG_MTD_NAND_SSFDC_GETGEO
+
+typedef struct {
+	unsigned long size;
+	unsigned short cyl;
+	unsigned char head;
+	unsigned char sec;
+} chs_entry_t;
+
+/* Must be ordered by size */
+static const chs_entry_t chs_table[] = {
+	{ MB(  1), 125,  4,  4 },
+	{ MB(  2), 125,  4,  8 },
+	{ MB(  4), 250,  4,  8 },
+	{ MB(  8), 250,  4, 16 },
+	{ MB( 16), 500,  4, 16 },
+	{ MB( 32), 500,  8, 16 },
+	{ MB( 64), 500,  8, 32 },
+	{ MB(128), 500, 16, 32 },
+	{ 0 },
+};
+
+static int get_chs(unsigned long size, unsigned short *cyl, unsigned char *head,
+			unsigned char *sec)
+{
+	int k;
+	int found = 0;
+
+	k = 0;
+	while (chs_table[k].size > 0 && size > chs_table[k].size)
+		k++;
+
+	if (chs_table[k].size > 0) {
+		if (cyl)
+			*cyl = chs_table[k].cyl;
+		if (head)
+			*head = chs_table[k].head;
+		if (sec)
+			*sec = chs_table[k].sec;
+		found = 1;
+	}
+
+	return found;
+}
+#endif
+
+/* These bytes are the signature for the CIS/IDI sector */
+static const uint8_t cis_numbers[] = {
+	0x01, 0x03, 0xD9, 0x01, 0xFF, 0x18, 0x02, 0xDF, 0x01, 0x20
+};
+
+
+/* Read and check for a valid CIS sector */
+static int get_valid_cis_sector(struct mtd_info *mtd)
+{
+	int ret, k, cis_sector;
+	size_t retlen;
+	loff_t offset;
+	uint8_t sect_buf[SECTOR_SIZE];
+
+	/*
+	 * Look for CIS/IDI sector on the first GOOD block (give up after 4 bad
+	 * blocks). If the first good block doesn't contain CIS number the flash
+	 * is not SSFDC formatted
+	 */
+	cis_sector = -1;
+	for (k = 0, offset = 0; k < 4; k++, offset += mtd->erasesize) {
+		if (!mtd->block_isbad(mtd, offset)) {
+			ret = mtd->read(mtd, offset, SECTOR_SIZE, &retlen,
+				sect_buf);
+
+			/* CIS pattern match on the sector buffer */
+			if ( ret < 0 || retlen != SECTOR_SIZE ) {
+				printk(KERN_WARNING
+					"SSFDC_RO:can't read CIS/IDI sector\n");
+			} else if ( !memcmp(sect_buf, cis_numbers,
+					sizeof(cis_numbers)) ) {
+				/* Found */
+				cis_sector = (int)(offset >> SECTOR_SHIFT);
+			} else {
+				DEBUG(MTD_DEBUG_LEVEL0,
+					"SSFDC_RO: CIS/IDI sector not found"
+					" on %s (mtd%d)\n", mtd->name,
+					mtd->index);
+			}
+			break;
+		}
+	}
+
+	return cis_sector;
+}
+
+/* Read physical sector (wrapper to MTD_READ) */
+static int read_physical_sector(struct mtd_info *mtd, uint8_t *sect_buf,
+				int sect_no)
+{
+	int ret;
+	size_t retlen;
+	loff_t offset = (loff_t)sect_no << SECTOR_SHIFT;
+
+	ret = mtd->read(mtd, offset, SECTOR_SIZE, &retlen, sect_buf);
+	if (ret < 0 || retlen != SECTOR_SIZE)
+		return -1;
+
+	return 0;
+}
+
+/* Read redundancy area (wrapper to MTD_READ_OOB */
+static int read_raw_oob(struct mtd_info *mtd, loff_t offs, uint8_t *buf)
+{
+	struct mtd_oob_ops ops;
+	int ret;
+
+	ops.mode = MTD_OOB_RAW;
+	ops.ooboffs = 0;
+	ops.ooblen = mtd->oobsize;
+	ops.len = OOB_SIZE;
+	ops.oobbuf = buf;
+	ops.datbuf = NULL;
+
+	ret = mtd->read_oob(mtd, offs, &ops);
+	if (ret < 0 || ops.retlen != OOB_SIZE)
+		return -1;
+
+	return 0;
+}
+
+/* Parity calculator on a word of n bit size */
+static int get_parity(int number, int size)
+{
+ 	int k;
+	int parity;
+
+	parity = 1;
+	for (k = 0; k < size; k++) {
+		parity += (number >> k);
+		parity &= 1;
+	}
+	return parity;
+}
+
+/* Read and validate the logical block address field stored in the OOB */
+static int get_logical_address(uint8_t *oob_buf)
+{
+	int block_address, parity;
+	int offset[2] = {6, 11}; /* offset of the 2 address fields within OOB */
+	int j;
+	int ok = 0;
+
+	/*
+	 * Look for the first valid logical address
+	 * Valid address has fixed pattern on most significant bits and
+	 * parity check
+	 */
+	for (j = 0; j < ARRAY_SIZE(offset); j++) {
+		block_address = ((int)oob_buf[offset[j]] << 8) |
+			oob_buf[offset[j]+1];
+
+		/* Check for the signature bits in the address field (MSBits) */
+		if ((block_address & ~0x7FF) == 0x1000) {
+			parity = block_address & 0x01;
+			block_address &= 0x7FF;
+			block_address >>= 1;
+
+			if (get_parity(block_address, 10) != parity) {
+				DEBUG(MTD_DEBUG_LEVEL0,
+					"SSFDC_RO: logical address field%d"
+					"parity error(0x%04X)\n", j+1,
+					block_address);
+			} else {
+				ok = 1;
+				break;
+			}
+		}
+	}
+
+	if ( !ok )
+		block_address = -2;
+
+	DEBUG(MTD_DEBUG_LEVEL3, "SSFDC_RO: get_logical_address() %d\n",
+		block_address);
+
+	return block_address;
+}
+
+
+/* Build the logic block map */
+static int build_logical_block_map(struct ssfdcr_record *ssfdc)
+{
+	unsigned long offset;
+	uint8_t oob_buf[OOB_SIZE];
+	int ret, block_address, phys_block;
+	struct mtd_info *mtd = ssfdc->mbd.mtd;
+
+	DEBUG(MTD_DEBUG_LEVEL1, "SSFDC_RO: build_block_map() nblks=%d (%luK)\n",
+		ssfdc->map_len, (unsigned long)ssfdc->map_len *
+		ssfdc->erase_size / 1024 );
+
+	/* Scan every physical block, skip CIS block */
+	for (phys_block = ssfdc->cis_block + 1; phys_block < ssfdc->map_len;
+			phys_block++) {
+		offset = (unsigned long)phys_block * ssfdc->erase_size;
+		if (mtd->block_isbad(mtd, offset))
+			continue;	/* skip bad blocks */
+
+		ret = read_raw_oob(mtd, offset, oob_buf);
+		if (ret < 0) {
+			DEBUG(MTD_DEBUG_LEVEL0,
+				"SSFDC_RO: mtd read_oob() failed at %lu\n",
+				offset);
+			return -1;
+		}
+		block_address = get_logical_address(oob_buf);
+
+		/* Skip invalid addresses */
+		if (block_address >= 0 &&
+				block_address < MAX_LOGIC_BLK_PER_ZONE) {
+			int zone_index;
+
+			zone_index = phys_block / MAX_PHYS_BLK_PER_ZONE;
+			block_address += zone_index * MAX_LOGIC_BLK_PER_ZONE;
+			ssfdc->logic_block_map[block_address] =
+				(unsigned short)phys_block;
+
+			DEBUG(MTD_DEBUG_LEVEL2,
+				"SSFDC_RO: build_block_map() phys_block=%d,"
+				"logic_block_addr=%d, zone=%d\n",
+				phys_block, block_address, zone_index);
+		}
+	}
+	return 0;
+}
+
+static void ssfdcr_add_mtd(struct mtd_blktrans_ops *tr, struct mtd_info *mtd)
+{
+	struct ssfdcr_record *ssfdc;
+	int cis_sector;
+
+	/* Check for small page NAND flash */
+	if (mtd->type != MTD_NANDFLASH || mtd->oobsize != OOB_SIZE)
+		return;
+
+	/* Check for SSDFC format by reading CIS/IDI sector */
+	cis_sector = get_valid_cis_sector(mtd);
+	if (cis_sector == -1)
+		return;
+
+	ssfdc = kzalloc(sizeof(struct ssfdcr_record), GFP_KERNEL);
+	if (!ssfdc) {
+		printk(KERN_WARNING
+			"SSFDC_RO: out of memory for data structures\n");
+		return;
+	}
+
+	ssfdc->mbd.mtd = mtd;
+	ssfdc->mbd.devnum = -1;
+	ssfdc->mbd.blksize = SECTOR_SIZE;
+	ssfdc->mbd.tr = tr;
+	ssfdc->mbd.readonly = 1;
+
+	ssfdc->cis_block = cis_sector / (mtd->erasesize >> SECTOR_SHIFT);
+	ssfdc->erase_size = mtd->erasesize;
+	ssfdc->map_len = mtd->size / mtd->erasesize;
+
+	DEBUG(MTD_DEBUG_LEVEL1,
+		"SSFDC_RO: cis_block=%d,erase_size=%d,map_len=%d,n_zones=%d\n",
+		ssfdc->cis_block, ssfdc->erase_size, ssfdc->map_len,
+		(ssfdc->map_len + MAX_PHYS_BLK_PER_ZONE - 1) /
+		MAX_PHYS_BLK_PER_ZONE);
+
+#ifdef CONFIG_MTD_NAND_SSFDC_GETGEO
+	/* Set geometry */
+	get_chs( mtd->size, NULL, &ssfdc->heads, &ssfdc->sectors);
+	ssfdc->cylinders = (unsigned short)((mtd->size >> SECTOR_SHIFT) /
+			((long)ssfdc->sectors * (long)ssfdc->heads));
+
+	DEBUG(MTD_DEBUG_LEVEL1, "SSFDC_RO: using C:%d H:%d S:%d == %ld sects\n",
+		ssfdc->cylinders, ssfdc->heads , ssfdc->sectors, 
+		(long)ssfdc->cylinders * (long)ssfdc->heads *
+		(long)ssfdc->sectors );
+
+	ssfdc->mbd.size = (long)ssfdc->heads * (long)ssfdc->cylinders *
+				(long)ssfdc->sectors;
+#else
+	ssfdc->mbd.size  = ssfdc->map_len * (ssfdc->erase_size >> SECTOR_SHIFT);
+#endif
+
+	/* Allocate logical block map */
+	ssfdc->logic_block_map = kmalloc( sizeof(ssfdc->logic_block_map[0]) *
+						ssfdc->map_len, GFP_KERNEL);
+	if (!ssfdc->logic_block_map) {
+		printk(KERN_WARNING
+			"SSFDC_RO: out of memory for data structures\n");
+		goto out_err;
+	}
+	memset(ssfdc->logic_block_map, 0xff, sizeof(ssfdc->logic_block_map[0]) *
+		ssfdc->map_len);
+
+	/* Build logical block map */
+	if (build_logical_block_map(ssfdc) < 0)
+		goto out_err;
+
+	/* Register device + partitions */
+	if (add_mtd_blktrans_dev(&ssfdc->mbd))
+		goto out_err;
+
+	printk(KERN_INFO "SSFDC_RO: Found ssfdc%c on mtd%d (%s)\n",
+		ssfdc->mbd.devnum + 'a', mtd->index, mtd->name);
+	return;
+
+out_err:
+	kfree(ssfdc->logic_block_map);
+        kfree(ssfdc);
+}
+
+static void ssfdcr_remove_dev(struct mtd_blktrans_dev *dev)
+{
+	struct ssfdcr_record *ssfdc = (struct ssfdcr_record *)dev;
+
+	DEBUG(MTD_DEBUG_LEVEL1, "SSFDC_RO: remove_dev (i=%d)\n", dev->devnum);
+
+	del_mtd_blktrans_dev(dev);
+	kfree(ssfdc->logic_block_map);
+	kfree(ssfdc);
+}
+
+static int ssfdcr_readsect(struct mtd_blktrans_dev *dev,
+				unsigned long logic_sect_no, char *buf)
+{
+	struct ssfdcr_record *ssfdc = (struct ssfdcr_record *)dev;
+	int sectors_per_block, offset, block_address;
+
+	sectors_per_block = ssfdc->erase_size >> SECTOR_SHIFT;
+	offset = (int)(logic_sect_no % sectors_per_block);
+	block_address = (int)(logic_sect_no / sectors_per_block);
+
+	DEBUG(MTD_DEBUG_LEVEL3,
+		"SSFDC_RO: ssfdcr_readsect(%lu) sec_per_blk=%d, ofst=%d,"
+		" block_addr=%d\n", logic_sect_no, sectors_per_block, offset,
+		block_address);
+
+	if (block_address >= ssfdc->map_len)
+		BUG();
+
+	block_address = ssfdc->logic_block_map[block_address];
+
+	DEBUG(MTD_DEBUG_LEVEL3,
+		"SSFDC_RO: ssfdcr_readsect() phys_block_addr=%d\n",
+		block_address);
+
+	if (block_address < 0xffff) {
+		unsigned long sect_no;
+
+		sect_no = (unsigned long)block_address * sectors_per_block +
+				offset;
+
+		DEBUG(MTD_DEBUG_LEVEL3,
+			"SSFDC_RO: ssfdcr_readsect() phys_sect_no=%lu\n",
+			sect_no);
+
+		if (read_physical_sector( ssfdc->mbd.mtd, buf, sect_no ) < 0)
+			return -EIO;
+	} else {
+		memset(buf, 0xff, SECTOR_SIZE);
+	}
+
+	return 0;
+}
+
+#ifdef CONFIG_MTD_NAND_SSFDC_GETGEO
+static int ssfdcr_getgeo(struct mtd_blktrans_dev *dev,  struct hd_geometry *geo)
+{
+	struct ssfdcr_record *ssfdc = (struct ssfdcr_record *)dev;
+
+	DEBUG(MTD_DEBUG_LEVEL1, "SSFDC_RO: ssfdcr_getgeo() C=%d, H=%d, S=%d\n",
+			ssfdc->cylinders, ssfdc->heads, ssfdc->sectors);
+
+	geo->heads = ssfdc->heads;
+	geo->sectors = ssfdc->sectors;
+	geo->cylinders = ssfdc->cylinders;
+
+	return 0;
+}
+#endif
+
+/****************************************************************************
+ *
+ * Module stuff
+ *
+ ****************************************************************************/
+
+static struct mtd_blktrans_ops ssfdcr_tr = {
+	.name		= "ssfdc",
+	.major		= SSFDCR_MAJOR,
+	.part_bits	= SSFDCR_PARTN_BITS,
+#ifdef CONFIG_MTD_NAND_SSFDC_GETGEO
+	.getgeo		= ssfdcr_getgeo,
+#endif
+	.readsect	= ssfdcr_readsect,
+	.add_mtd	= ssfdcr_add_mtd,
+	.remove_dev	= ssfdcr_remove_dev,
+	.owner		= THIS_MODULE,
+};
+
+static int __init init_ssfdcr(void)
+{
+	printk(KERN_INFO "SSFDC read-only Flash Translation layer\n");
+
+	return register_mtd_blktrans(&ssfdcr_tr);
+}
+
+static void __exit cleanup_ssfdcr(void)
+{
+	deregister_mtd_blktrans(&ssfdcr_tr);
+}
+
+module_init(init_ssfdcr);
+module_exit(cleanup_ssfdcr);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Claudio Lanconelli <lanconelli.claudio@eptar.com>");
+MODULE_DESCRIPTION("Flash Translation Layer for read-only SSFDC SmartMedia card");