berlin_tools/bootloader/android/flash_ts.c - manifest_repos/bootloader - Git at Google

 /*
  * Flash-based transactional key-value store
  *
  * Copyright (C) 2011 Google, Inc.
  * Author: Eugene Surovegin, Terry Heo
  */

 #include "common.h"
 #include "nflash_drv.h"
 #include "config.h"
 #include "nand_priv.h"
 #include "com_type.h"
 #include "debug.h"
 #include "errno-base.h"
 #include "string.h"
 #include "flash_ts.h"

 #define printf          lgpl_printf
 #define min(a,b)        (((a) < (b)) ? (a) : (b))
 #define NAND_INT_PAGE_BUFF_SIZE         ((MV_NAND_MAX_PAGE_SIZE + MV_NAND_MAX_OOB_SIZE) / 4)
 #define EMMC_INT_PAGE_BUFF_SIZE         (8448/4 + 32)
 #define ALIGNED(val, n)                 ((((unsigned int)val) + (n) - 1) & (~((unsigned int)(n) - 1)))

 extern struct mv_nand_data nand_data ;
 extern unsigned long simple_strtoul(const char *cp,char **endp,unsigned int base);

 inline int nand_page_size() {
     return (nand_data.szofpg);

 }

 inline int nand_block_size() {
     return (nand_data.szofblk);
 }

 inline int nand_read_page(int page, void *buf, int size) {
 #ifdef NAND_BOOT
     static int page_buff[NAND_INT_PAGE_BUFF_SIZE];
 #elif defined(EMMC_BOOT)
     static int temp[EMMC_INT_PAGE_BUFF_SIZE];
     int *page_buff;
     page_buff = (int *)ALIGNED(temp, 32);
 #else
 #error
 #endif
     loff_t offset = page * nand_page_size();

     if (size > nand_page_size()) {
         return -1;
     }
     if (NFlash_PageRead(offset, page_buff)) {
         // page may be not erased. return default data.
         memset(buf, 0xff, size);
         return 0;
     }
     UtilMemCpy(buf, page_buff, size);
     return 0;
 }

 inline int nand_write_page(int page, const void *buf, int size) {
 #ifdef NAND_BOOT
     static int page_buff[NAND_INT_PAGE_BUFF_SIZE];
 #elif defined(EMMC_BOOT)
     static int temp[EMMC_INT_PAGE_BUFF_SIZE];
     int *page_buff;
     page_buff = (int *)ALIGNED(temp, 32);
 #else
 #error
 #endif
     loff_t offset = page * nand_page_size();

     if (size > nand_page_size()) {
         return -1;
     }
     memset(page_buff, 0xff, sizeof(page_buff));
     UtilMemCpy(page_buff, buf, size);
     if (NFlash_PageWrite(offset, page_buff)) {
         lgpl_printf("Write failed @ 0x%08x\n", (unsigned)offset);
         return -1;
     }
     return 0;
 }

 /* Compatibility defines to keep code as similar as possible
  * to the Linux version.
  */
 #define DRV_NAME		"fts"
 static inline int is_power_of_2(unsigned int n)
 {
 	return (n != 0 && ((n & (n - 1)) == 0));
 }

 //typedef unsigned u32;
 //typedef long loff_t;
 #define likely(x)		__builtin_expect(!!(x), 1)
 #define unlikely(x)		__builtin_expect(!!(x), 0)

 /* Keep in sync with 'struct flash_ts' */
 #define FLASH_TS_HDR_SIZE	(4 * sizeof(u32))
 #define FLASH_TS_MAX_SIZE	(16 * 1024)
 #define FLASH_TS_MAX_DATA_SIZE	(FLASH_TS_MAX_SIZE - FLASH_TS_HDR_SIZE)

 #define FLASH_TS_MAGIC		0x53542a46

 /* Physical flash layout */
 struct flash_ts {
 	u32 magic;		/* "F*TS" */
 	u32 crc;		/* doesn't include magic and crc fields */
 	u32 len;		/* real size of data */
 	u32 version;		/* generation counter, must be positive */

 	/* data format is very similar to Unix environment:
 	 *   key1=value1\0key2=value2\0\0
 	 */
 	char data[FLASH_TS_MAX_DATA_SIZE];
 };

 /* Internal state */
 static struct flash_ts_priv {
 	/* chunk size, >= sizeof(struct flash_ts) */
 	size_t chunk;

 	/* current record offset within NAND partition */
 	loff_t offset;

 	loff_t base;		/* NAND partition base offset */
 	size_t size;		/* NAND partition size */
 	size_t erasesize;	/* block size */
 	size_t writesize;	/* page size */

 	/* in-memory copy of flash content */
 	struct flash_ts cache;

 	/* temporary buffers
 	 *  - one backup for failure rollback
 	 *  - another for read-after-write verification
 	 */
 	struct flash_ts cache_tmp_backup;
 	struct flash_ts cache_tmp_verify;
 } __ts_priv;
 static struct flash_ts_priv *__ts = NULL;

 static int flash_block_isbad(struct flash_ts_priv *ts, loff_t off)
 {
 	return is_block_bad(ts->base + off);
 }

 static int flash_erase(struct flash_ts_priv *ts, loff_t off)
 {
 	lgpl_printf(DRV_NAME ": flash_erase @ 0x%08x\n", (unsigned)(ts->base + off));
 	int res = NFlash_Erase(ts->base + off);
 	if (unlikely(res))
 		printf(DRV_NAME ": flash_erase(0x%08x) failed, errno %d\n",
 		       (unsigned)off, res);
 	return res;
 }

 static int flash_write(struct flash_ts_priv *ts, loff_t off,
 		       const void *buf, size_t size)
 {
 	int page = (ts->base + off) / ts->writesize;
 	int res = 0;

 	while (size) {
 		size_t chunk = min(size, ts->writesize);
 		res = nand_write_page(page, buf, chunk);
 		if (likely(!res)) {
 			++page;
 			buf = (const void*)((unsigned long)buf + chunk);
 			size -= chunk;
 		} else {
 			printf(DRV_NAME ": write_page(%u) failed, errno %d\n",
 			       page, res);
 			break;
 		}
 	}
 	return res;
 }

 static int flash_read(struct flash_ts_priv *ts, loff_t off, void *buf, size_t size)
 {
 	int page = (ts->base + off) / ts->writesize;
 	int res = 0;

 	while (size) {
 		size_t chunk = min(size, ts->writesize);
 		res = nand_read_page(page, buf, chunk);
 		if (likely(!res)) {
 			++page;
 			buf = (void*)((unsigned long)buf + chunk);
 			size -= chunk;
 		} else {
 			printf(DRV_NAME ": read_page(%u), errno %d\n",
 			       page, res);
 			break;
 		}
 	}
 	return res;
 }

 static char *flash_ts_find(struct flash_ts_priv *ts, const char *key,
 			   size_t key_len)
 {
 	char *s = ts->cache.data;
 	while (*s) {
 		if (!strncmp(s, key, key_len)) {
 			if (s[key_len] == '=')
 				return s;
 		}

 		s += strlen(s) + 1;
 	}
 	return NULL;
 }


 static inline u32 flash_ts_crc(const struct flash_ts *cache)
 {
 	const unsigned char *p;
 	u32 crc = 0;
 	size_t len;

 	/* skip magic and crc fields */
 	len = cache->len + 2 * sizeof(u32);
 	p = (const unsigned char*)&cache->len;

 	while (len--) {
 		int i;

 		crc ^= *p++;
 		for (i = 0; i < 8; i++)
 			crc = (crc >> 1) ^ ((crc & 1) ? 0xedb88320 : 0);
 	}
 	return crc ^ ~0;
 }

 /* Verifies cache consistency and locks it */
 static struct flash_ts_priv *__flash_ts_get(void)
 {
 	struct flash_ts_priv *ts = __ts;

 	if (likely(ts)) {
 		if (unlikely(ts->cache.crc != flash_ts_crc(&ts->cache))) {
 			printf(DRV_NAME
 			       ": memory corruption detected\n");
 			ts = NULL;
 		}
 	} else {
 		printf(DRV_NAME ": not initialized yet\n");
 	}

 	return ts;
 }

 static int flash_ts_commit(struct flash_ts_priv *ts)
 {
 	loff_t off = ts->offset + ts->chunk;
 	/* we try to make two passes to handle non-erased blocks
 	 * this should only matter for the inital pass over the whole device.
 	 */
 	int max_iterations = (ts->size / ts->erasesize) * 2;
 	size_t size = (FLASH_TS_HDR_SIZE + ts->cache.len + ts->chunk - 1)
 		       & ~(ts->chunk - 1);

 	/* fill unused part of data */
 	memset(ts->cache.data + ts->cache.len, 0xff,
 	       sizeof(ts->cache.data) - ts->cache.len);

 	while (max_iterations--) {
 		/* wrap around */
 		if (off >= ts->size)
 			off = 0;

 		/* new block? */
 		if (!(off & (ts->erasesize - 1))) {
 			if (flash_block_isbad(ts, off)) {
 				/* skip this block */
 				off += ts->erasesize;
 				continue;
 			}

 			if (unlikely(flash_erase(ts, off))) {
 				/* skip this block */
 				off += ts->erasesize;
 				continue;
 			}
 		}

 		/* write and read back to veryfy */
 		if (flash_write(ts, off, &ts->cache, size) ||
 		    flash_read(ts, off, &ts->cache_tmp_verify, size)) {
 			/* hmm, probably unclean block, skip it for now */
 			off = (off + ts->erasesize) & ~(ts->erasesize - 1);
 			continue;
 		}

 		/* compare */
 		if (memcmp(&ts->cache, &ts->cache_tmp_verify, size)) {
 			printf(DRV_NAME
 			       ": record v%u read mismatch @ 0x%08x\n",
 				(unsigned)ts->cache.version, (unsigned)off);
 			/* skip this block for now */
 			off = (off + ts->erasesize) & ~(ts->erasesize - 1);
 			continue;
 		}

 		/* for new block, erase the previous block after write done,
 		 * it's to speed up flash_ts_scan
 		 */
 		if (!(off & (ts->erasesize - 1))) {
 			loff_t pre_block_base = ts->offset & ~(ts->erasesize - 1);
 			loff_t cur_block_base = off & ~(ts->erasesize - 1);
 			if (cur_block_base != pre_block_base)
 				flash_erase(ts, pre_block_base);
 		}
 		ts->offset = off;
 		printf(DRV_NAME ": record v%u commited @ 0x%08x\n",
 		       (unsigned)ts->cache.version, (unsigned)off);
 		return 0;
 	}

 	printf(DRV_NAME ": commit failure\n");
 	return -EIO;
 }

 int flash_ts_set(const char *key, const char *value)
 {
 	struct flash_ts_priv *ts;
 	size_t klen = strlen(key);
 	size_t vlen = strlen(value);
 	int res;
 	char *p;

 	ts = __flash_ts_get();
 	if (unlikely(!ts))
 		return -EINVAL;

 	/* save current cache contents so we can restore it on failure */
 	memcpy(&ts->cache_tmp_backup, &ts->cache, sizeof(ts->cache_tmp_backup));

 	p = flash_ts_find(ts, key, klen);
 	if (p) {
 		/* we are replacing existing entry,
 		 * empty value (vlen == 0) removes entry completely.
 		 */
 		size_t cur_len = strlen(p) + 1;
 		size_t new_len = vlen ? klen + 1 + vlen + 1 : 0;

 		if (cur_len != new_len) {
 			/* we need to move stuff around */

 			if ((ts->cache.len - cur_len) + new_len >
 			     sizeof(ts->cache.data))
 				goto no_space;

 			memmove(p + new_len, p + cur_len,
 				ts->cache.len - (p - ts->cache.data + cur_len));

 			ts->cache.len = (ts->cache.len - cur_len) + new_len;
 		} else if (!strcmp(p + klen + 1, value)) {
 			/* skip update if new value is the same as the old one */
 			res = 0;
 			goto out;
 		}

 		if (vlen) {
 			p += klen + 1;
 			memcpy(p, value, vlen);
 			p[vlen] = '\0';
 		}
 	} else {
 		size_t len = klen + 1 + vlen + 1;

 		/* don't do anything if value is empty */
 		if (!vlen) {
 			res = 0;
 			goto out;
 		}

 		if (ts->cache.len + len > sizeof(ts->cache.data))
 			goto no_space;

 		/* add new entry at the end */
 		p = ts->cache.data + ts->cache.len - 1;
 		memcpy(p, key, klen);
 		p += klen;
 		*p++ = '=';
 		memcpy(p, value, vlen);
 		p += vlen;
 		*p++ = '\0';
 		*p = '\0';
 		ts->cache.len += len;
 	}

 	++ts->cache.version;
 	ts->cache.crc = flash_ts_crc(&ts->cache);
 	res = flash_ts_commit(ts);
 	if (unlikely(res))
 		memcpy(&ts->cache, &ts->cache_tmp_backup, sizeof(ts->cache));
 	goto out;

     no_space:
 	printf(DRV_NAME ": no space left for '%s=%s'\n", key, value);
 	res = -ENOSPC;
     out:

 	return res;
 }

 void flash_ts_get(const char *key, char *value, unsigned int size)
 {
 	size_t klen = strlen(key);
 	struct flash_ts_priv *ts;
 	const char *p;

 	*value = '\0';

 	ts = __flash_ts_get();
 	if (unlikely(!ts))
 		return;

 	p = flash_ts_find(ts, key, klen);
 	if (p)
 		strlcpy(value, p + klen + 1, size);
 }

 int flash_ts_get_int(const char *key, int default_value)
 {
 	char value[16];
 	int res;

 	flash_ts_get(key, value, sizeof(value));
 	if (!value[0])
 		return default_value;

 	res = (int)simple_strtoul(value, (char**)NULL, 0);
 	return res;
 }

 static inline u32 flash_ts_check_header(const struct flash_ts *cache)
 {
 	if (cache->magic == FLASH_TS_MAGIC &&
 	    cache->version &&
 	    cache->len && cache->len <= sizeof(cache->data) &&
 	    cache->crc == flash_ts_crc(cache) &&
 	    /* check correct null-termination */
 	    !cache->data[cache->len - 1] &&
 	    (cache->len == 1 || !cache->data[cache->len - 2])) {
 	    	/* all is good */
 		return cache->version;
 	}

 	return 0;
 }

 static int flash_ts_scan(struct flash_ts_priv *ts)
 {
 	int res, good_blocks = 0;
 	loff_t off = 0;

 	do {
 		/* new block ? */
 		if (!(off & (ts->erasesize - 1))) {
 			if (flash_block_isbad(ts, off)) {
 				printf(DRV_NAME
 			       	       ": skipping bad block @ 0x%08x\n",
 			       	       (unsigned)off);
 				off += ts->erasesize;
 				continue;
 			} else
 				++good_blocks;
 		}

 		res = flash_read(ts, off, &ts->cache_tmp_verify,
 				 sizeof(ts->cache_tmp_verify));
 		if (!res) {
 			u32 version =
 			    flash_ts_check_header(&ts->cache_tmp_verify);
 			if (version > ts->cache.version) {
 				memcpy(&ts->cache, &ts->cache_tmp_verify,
 				       sizeof(ts->cache));
 				ts->offset = off;
 			}
 			if (0 == version &&
 				is_blank(&ts->cache_tmp_verify,
 					sizeof(ts->cache_tmp_verify))) {
 				/* skip the whole block if chunk is blank */
 				off = (off + ts->erasesize) & ~(ts->erasesize - 1);
 			} else
 				off += ts->chunk;
 		} else {
 			off += ts->chunk;
 		}
 	} while (off < ts->size);

 	if (unlikely(!good_blocks)) {
 		printf(DRV_NAME ": no good blocks\n");
 		return -ENODEV;
 	}

 	if (unlikely(good_blocks < 2))
 		printf(DRV_NAME ": less than 2 good blocks,"
 				" reliability is not guaranteed\n");
 	return 0;
 }

 /* Round-up to the next power-of-2,
  * from "Hacker's Delight" by Henry S. Warren.
  */
 static inline u32 clp2(u32 x)
 {
 	--x;
 	x |= x >> 1;
 	x |= x >> 2;
 	x |= x >> 4;
 	x |= x >> 8;
 	x |= x >> 16;
 	return x + 1;
 }

 int flash_ts_init(int start_block, int blocks)
 {
 	struct flash_ts_priv *ts = &__ts_priv;
 	int writesize = nand_page_size();
 	int erasesize = nand_block_size();
 	int res;

 	/* make sure both page and block sizes are power-of-2
 	 * (this will make chunk size determination simpler).
 	 */
 	if (unlikely(writesize < 0 || !is_power_of_2(writesize) ||
 		     erasesize < 0 || !is_power_of_2(erasesize))) {
 		printf(DRV_NAME ": unsupported flash geometry: erasesize=%d, writesize=%d\n",
 			erasesize, writesize);
 		return -ENODEV;
 	}

 	/* determine chunk size so it doesn't cross block boundary,
 	 * is multiple of page size and there is no wasted space in a block.
 	 * We assume page and block sizes are power-of-2.
 	 */
 	ts->chunk = clp2((sizeof(struct flash_ts) + writesize - 1) &
 			 ~(writesize - 1));
 	if (unlikely(ts->chunk > (unsigned int)erasesize)) {
 		printf(DRV_NAME ": NAND block size is too small\n");
 		return -ENODEV;
 	}

 	if (writesize > MV_NAND_MAX_PAGE_SIZE) {
 		printf(DRV_NAME ": NAND page size is too large\n");
 		return -ENODEV;
 	}

 	/* write flash information */
 	ts->size = blocks * erasesize;
 	ts->base = start_block * erasesize;
 	ts->erasesize = erasesize;
 	ts->writesize = writesize;

 	/* default empty state */
 	ts->offset = ts->size - ts->chunk;
 	ts->cache.magic = FLASH_TS_MAGIC;
 	ts->cache.version = 0;
 	ts->cache.len = 1;
 	ts->cache.data[0] = '\0';
 	ts->cache.crc = flash_ts_crc(&ts->cache);

 	/* scan flash partition for the most recent record */
 	res = flash_ts_scan(ts);
 	if (unlikely(res))
 		return res;

 	if (ts->cache.version)
 		printf(DRV_NAME ": v%u loaded from 0x%08x\n",
 		       (unsigned)ts->cache.version, (unsigned)ts->offset);

 	/* "enable" it */
 	__ts = ts;

 	return res;
 }
	/*
	* Flash-based transactional key-value store
	*
	* Copyright (C) 2011 Google, Inc.
	* Author: Eugene Surovegin, Terry Heo
	*/

	#include "common.h"
	#include "nflash_drv.h"
	#include "config.h"
	#include "nand_priv.h"
	#include "com_type.h"
	#include "debug.h"
	#include "errno-base.h"
	#include "string.h"
	#include "flash_ts.h"

	#define printf lgpl_printf
	#define min(a,b) (((a) < (b)) ? (a) : (b))
	#define NAND_INT_PAGE_BUFF_SIZE ((MV_NAND_MAX_PAGE_SIZE + MV_NAND_MAX_OOB_SIZE) / 4)
	#define EMMC_INT_PAGE_BUFF_SIZE (8448/4 + 32)
	#define ALIGNED(val, n) ((((unsigned int)val) + (n) - 1) & (~((unsigned int)(n) - 1)))

	extern struct mv_nand_data nand_data ;
	extern unsigned long simple_strtoul(const char cp,char *endp,unsigned int base);

	inline int nand_page_size() {
	return (nand_data.szofpg);

	}

	inline int nand_block_size() {
	return (nand_data.szofblk);
	}

	inline int nand_read_page(int page, void *buf, int size) {
	#ifdef NAND_BOOT
	static int page_buff[NAND_INT_PAGE_BUFF_SIZE];
	#elif defined(EMMC_BOOT)
	static int temp[EMMC_INT_PAGE_BUFF_SIZE];
	int *page_buff;
	page_buff = (int *)ALIGNED(temp, 32);
	#else
	#error
	#endif
	loff_t offset = page * nand_page_size();

	if (size > nand_page_size()) {
	return -1;
	}
	if (NFlash_PageRead(offset, page_buff)) {
	// page may be not erased. return default data.
	memset(buf, 0xff, size);
	return 0;
	}
	UtilMemCpy(buf, page_buff, size);
	return 0;
	}

	inline int nand_write_page(int page, const void *buf, int size) {
	#ifdef NAND_BOOT
	static int page_buff[NAND_INT_PAGE_BUFF_SIZE];
	#elif defined(EMMC_BOOT)
	static int temp[EMMC_INT_PAGE_BUFF_SIZE];
	int *page_buff;
	page_buff = (int *)ALIGNED(temp, 32);
	#else
	#error
	#endif
	loff_t offset = page * nand_page_size();

	if (size > nand_page_size()) {
	return -1;
	}
	memset(page_buff, 0xff, sizeof(page_buff));
	UtilMemCpy(page_buff, buf, size);
	if (NFlash_PageWrite(offset, page_buff)) {
	lgpl_printf("Write failed @ 0x%08x\n", (unsigned)offset);
	return -1;
	}
	return 0;
	}

	/* Compatibility defines to keep code as similar as possible
	* to the Linux version.
	*/
	#define DRV_NAME "fts"
	static inline int is_power_of_2(unsigned int n)
	{
	return (n != 0 && ((n & (n - 1)) == 0));
	}

	//typedef unsigned u32;
	//typedef long loff_t;
	#define likely(x) __builtin_expect(!!(x), 1)
	#define unlikely(x) __builtin_expect(!!(x), 0)

	/* Keep in sync with 'struct flash_ts' */
	#define FLASH_TS_HDR_SIZE (4 * sizeof(u32))
	#define FLASH_TS_MAX_SIZE (16 * 1024)
	#define FLASH_TS_MAX_DATA_SIZE (FLASH_TS_MAX_SIZE - FLASH_TS_HDR_SIZE)

	#define FLASH_TS_MAGIC 0x53542a46

	/* Physical flash layout */
	struct flash_ts {
	u32 magic; /* "FTS" /
	u32 crc; /* doesn't include magic and crc fields */
	u32 len; /* real size of data */
	u32 version; /* generation counter, must be positive */

	/* data format is very similar to Unix environment:
	* key1=value1\0key2=value2\0\0
	*/
	char data[FLASH_TS_MAX_DATA_SIZE];
	};

	/* Internal state */
	static struct flash_ts_priv {
	/* chunk size, >= sizeof(struct flash_ts) */
	size_t chunk;

	/* current record offset within NAND partition */
	loff_t offset;

	loff_t base; /* NAND partition base offset */
	size_t size; /* NAND partition size */
	size_t erasesize; /* block size */
	size_t writesize; /* page size */

	/* in-memory copy of flash content */
	struct flash_ts cache;

	/* temporary buffers
	* - one backup for failure rollback
	* - another for read-after-write verification
	*/
	struct flash_ts cache_tmp_backup;
	struct flash_ts cache_tmp_verify;
	} __ts_priv;
	static struct flash_ts_priv *__ts = NULL;

	static int flash_block_isbad(struct flash_ts_priv *ts, loff_t off)
	{
	return is_block_bad(ts->base + off);
	}

	static int flash_erase(struct flash_ts_priv *ts, loff_t off)
	{
	lgpl_printf(DRV_NAME ": flash_erase @ 0x%08x\n", (unsigned)(ts->base + off));
	int res = NFlash_Erase(ts->base + off);
	if (unlikely(res))
	printf(DRV_NAME ": flash_erase(0x%08x) failed, errno %d\n",
	(unsigned)off, res);
	return res;
	}

	static int flash_write(struct flash_ts_priv *ts, loff_t off,
	const void *buf, size_t size)
	{
	int page = (ts->base + off) / ts->writesize;
	int res = 0;

	while (size) {
	size_t chunk = min(size, ts->writesize);
	res = nand_write_page(page, buf, chunk);
	if (likely(!res)) {
	++page;
	buf = (const void*)((unsigned long)buf + chunk);
	size -= chunk;
	} else {
	printf(DRV_NAME ": write_page(%u) failed, errno %d\n",
	page, res);
	break;
	}
	}
	return res;
	}

	static int flash_read(struct flash_ts_priv ts, loff_t off, void buf, size_t size)
	{
	int page = (ts->base + off) / ts->writesize;
	int res = 0;

	while (size) {
	size_t chunk = min(size, ts->writesize);
	res = nand_read_page(page, buf, chunk);
	if (likely(!res)) {
	++page;
	buf = (void*)((unsigned long)buf + chunk);
	size -= chunk;
	} else {
	printf(DRV_NAME ": read_page(%u), errno %d\n",
	page, res);
	break;
	}
	}
	return res;
	}

	static char flash_ts_find(struct flash_ts_priv ts, const char *key,
	size_t key_len)
	{
	char *s = ts->cache.data;
	while (*s) {
	if (!strncmp(s, key, key_len)) {
	if (s[key_len] == '=')
	return s;
	}

	s += strlen(s) + 1;
	}
	return NULL;
	}


	static inline u32 flash_ts_crc(const struct flash_ts *cache)
	{
	const unsigned char *p;
	u32 crc = 0;
	size_t len;

	/* skip magic and crc fields */
	len = cache->len + 2 * sizeof(u32);
	p = (const unsigned char*)&cache->len;

	while (len--) {
	int i;

	crc ^= *p++;
	for (i = 0; i < 8; i++)
	crc = (crc >> 1) ^ ((crc & 1) ? 0xedb88320 : 0);
	}
	return crc ^ ~0;
	}

	/* Verifies cache consistency and locks it */
	static struct flash_ts_priv *__flash_ts_get(void)
	{
	struct flash_ts_priv *ts = __ts;

	if (likely(ts)) {
	if (unlikely(ts->cache.crc != flash_ts_crc(&ts->cache))) {
	printf(DRV_NAME
	": memory corruption detected\n");
	ts = NULL;
	}
	} else {
	printf(DRV_NAME ": not initialized yet\n");
	}

	return ts;
	}

	static int flash_ts_commit(struct flash_ts_priv *ts)
	{
	loff_t off = ts->offset + ts->chunk;
	/* we try to make two passes to handle non-erased blocks
	* this should only matter for the inital pass over the whole device.
	*/
	int max_iterations = (ts->size / ts->erasesize) * 2;
	size_t size = (FLASH_TS_HDR_SIZE + ts->cache.len + ts->chunk - 1)
	& ~(ts->chunk - 1);

	/* fill unused part of data */
	memset(ts->cache.data + ts->cache.len, 0xff,
	sizeof(ts->cache.data) - ts->cache.len);

	while (max_iterations--) {
	/* wrap around */
	if (off >= ts->size)
	off = 0;

	/* new block? */
	if (!(off & (ts->erasesize - 1))) {
	if (flash_block_isbad(ts, off)) {
	/* skip this block */
	off += ts->erasesize;
	continue;
	}

	if (unlikely(flash_erase(ts, off))) {
	/* skip this block */
	off += ts->erasesize;
	continue;
	}
	}

	/* write and read back to veryfy */
	if (flash_write(ts, off, &ts->cache, size) \|\|
	flash_read(ts, off, &ts->cache_tmp_verify, size)) {
	/* hmm, probably unclean block, skip it for now */
	off = (off + ts->erasesize) & ~(ts->erasesize - 1);
	continue;
	}

	/* compare */
	if (memcmp(&ts->cache, &ts->cache_tmp_verify, size)) {
	printf(DRV_NAME
	": record v%u read mismatch @ 0x%08x\n",
	(unsigned)ts->cache.version, (unsigned)off);
	/* skip this block for now */
	off = (off + ts->erasesize) & ~(ts->erasesize - 1);
	continue;
	}

	/* for new block, erase the previous block after write done,
	* it's to speed up flash_ts_scan
	*/
	if (!(off & (ts->erasesize - 1))) {
	loff_t pre_block_base = ts->offset & ~(ts->erasesize - 1);
	loff_t cur_block_base = off & ~(ts->erasesize - 1);
	if (cur_block_base != pre_block_base)
	flash_erase(ts, pre_block_base);
	}
	ts->offset = off;
	printf(DRV_NAME ": record v%u commited @ 0x%08x\n",
	(unsigned)ts->cache.version, (unsigned)off);
	return 0;
	}

	printf(DRV_NAME ": commit failure\n");
	return -EIO;
	}

	int flash_ts_set(const char key, const char value)
	{
	struct flash_ts_priv *ts;
	size_t klen = strlen(key);
	size_t vlen = strlen(value);
	int res;
	char *p;

	ts = __flash_ts_get();
	if (unlikely(!ts))
	return -EINVAL;

	/* save current cache contents so we can restore it on failure */
	memcpy(&ts->cache_tmp_backup, &ts->cache, sizeof(ts->cache_tmp_backup));

	p = flash_ts_find(ts, key, klen);
	if (p) {
	/* we are replacing existing entry,
	* empty value (vlen == 0) removes entry completely.
	*/
	size_t cur_len = strlen(p) + 1;
	size_t new_len = vlen ? klen + 1 + vlen + 1 : 0;

	if (cur_len != new_len) {
	/* we need to move stuff around */

	if ((ts->cache.len - cur_len) + new_len >
	sizeof(ts->cache.data))
	goto no_space;

	memmove(p + new_len, p + cur_len,
	ts->cache.len - (p - ts->cache.data + cur_len));

	ts->cache.len = (ts->cache.len - cur_len) + new_len;
	} else if (!strcmp(p + klen + 1, value)) {
	/* skip update if new value is the same as the old one */
	res = 0;
	goto out;
	}

	if (vlen) {
	p += klen + 1;
	memcpy(p, value, vlen);
	p[vlen] = '\0';
	}
	} else {
	size_t len = klen + 1 + vlen + 1;

	/* don't do anything if value is empty */
	if (!vlen) {
	res = 0;
	goto out;
	}

	if (ts->cache.len + len > sizeof(ts->cache.data))
	goto no_space;

	/* add new entry at the end */
	p = ts->cache.data + ts->cache.len - 1;
	memcpy(p, key, klen);
	p += klen;
	*p++ = '=';
	memcpy(p, value, vlen);
	p += vlen;
	*p++ = '\0';
	*p = '\0';
	ts->cache.len += len;
	}

	++ts->cache.version;
	ts->cache.crc = flash_ts_crc(&ts->cache);
	res = flash_ts_commit(ts);
	if (unlikely(res))
	memcpy(&ts->cache, &ts->cache_tmp_backup, sizeof(ts->cache));
	goto out;

	no_space:
	printf(DRV_NAME ": no space left for '%s=%s'\n", key, value);
	res = -ENOSPC;
	out:

	return res;
	}

	void flash_ts_get(const char key, char value, unsigned int size)
	{
	size_t klen = strlen(key);
	struct flash_ts_priv *ts;
	const char *p;

	*value = '\0';

	ts = __flash_ts_get();
	if (unlikely(!ts))
	return;

	p = flash_ts_find(ts, key, klen);
	if (p)
	strlcpy(value, p + klen + 1, size);
	}

	int flash_ts_get_int(const char *key, int default_value)
	{
	char value[16];
	int res;

	flash_ts_get(key, value, sizeof(value));
	if (!value[0])
	return default_value;

	res = (int)simple_strtoul(value, (char**)NULL, 0);
	return res;
	}

	static inline u32 flash_ts_check_header(const struct flash_ts *cache)
	{
	if (cache->magic == FLASH_TS_MAGIC &&
	cache->version &&
	cache->len && cache->len <= sizeof(cache->data) &&
	cache->crc == flash_ts_crc(cache) &&
	/* check correct null-termination */
	!cache->data[cache->len - 1] &&
	(cache->len == 1 \|\| !cache->data[cache->len - 2])) {
	/* all is good */
	return cache->version;
	}

	return 0;
	}

	static int flash_ts_scan(struct flash_ts_priv *ts)
	{
	int res, good_blocks = 0;
	loff_t off = 0;

	do {
	/* new block ? */
	if (!(off & (ts->erasesize - 1))) {
	if (flash_block_isbad(ts, off)) {
	printf(DRV_NAME
	": skipping bad block @ 0x%08x\n",
	(unsigned)off);
	off += ts->erasesize;
	continue;
	} else
	++good_blocks;
	}

	res = flash_read(ts, off, &ts->cache_tmp_verify,
	sizeof(ts->cache_tmp_verify));
	if (!res) {
	u32 version =
	flash_ts_check_header(&ts->cache_tmp_verify);
	if (version > ts->cache.version) {
	memcpy(&ts->cache, &ts->cache_tmp_verify,
	sizeof(ts->cache));
	ts->offset = off;
	}
	if (0 == version &&
	is_blank(&ts->cache_tmp_verify,
	sizeof(ts->cache_tmp_verify))) {
	/* skip the whole block if chunk is blank */
	off = (off + ts->erasesize) & ~(ts->erasesize - 1);
	} else
	off += ts->chunk;
	} else {
	off += ts->chunk;
	}
	} while (off < ts->size);

	if (unlikely(!good_blocks)) {
	printf(DRV_NAME ": no good blocks\n");
	return -ENODEV;
	}

	if (unlikely(good_blocks < 2))
	printf(DRV_NAME ": less than 2 good blocks,"
	" reliability is not guaranteed\n");
	return 0;
	}

	/* Round-up to the next power-of-2,
	* from "Hacker's Delight" by Henry S. Warren.
	*/
	static inline u32 clp2(u32 x)
	{
	--x;
	x \|= x >> 1;
	x \|= x >> 2;
	x \|= x >> 4;
	x \|= x >> 8;
	x \|= x >> 16;
	return x + 1;
	}

	int flash_ts_init(int start_block, int blocks)
	{
	struct flash_ts_priv *ts = &__ts_priv;
	int writesize = nand_page_size();
	int erasesize = nand_block_size();
	int res;

	/* make sure both page and block sizes are power-of-2
	* (this will make chunk size determination simpler).
	*/
	if (unlikely(writesize < 0 \|\| !is_power_of_2(writesize) \|\|
	erasesize < 0 \|\| !is_power_of_2(erasesize))) {
	printf(DRV_NAME ": unsupported flash geometry: erasesize=%d, writesize=%d\n",
	erasesize, writesize);
	return -ENODEV;
	}

	/* determine chunk size so it doesn't cross block boundary,
	* is multiple of page size and there is no wasted space in a block.
	* We assume page and block sizes are power-of-2.
	*/
	ts->chunk = clp2((sizeof(struct flash_ts) + writesize - 1) &
	~(writesize - 1));
	if (unlikely(ts->chunk > (unsigned int)erasesize)) {
	printf(DRV_NAME ": NAND block size is too small\n");
	return -ENODEV;
	}

	if (writesize > MV_NAND_MAX_PAGE_SIZE) {
	printf(DRV_NAME ": NAND page size is too large\n");
	return -ENODEV;
	}

	/* write flash information */
	ts->size = blocks * erasesize;
	ts->base = start_block * erasesize;
	ts->erasesize = erasesize;
	ts->writesize = writesize;

	/* default empty state */
	ts->offset = ts->size - ts->chunk;
	ts->cache.magic = FLASH_TS_MAGIC;
	ts->cache.version = 0;
	ts->cache.len = 1;
	ts->cache.data[0] = '\0';
	ts->cache.crc = flash_ts_crc(&ts->cache);

	/* scan flash partition for the most recent record */
	res = flash_ts_scan(ts);
	if (unlikely(res))
	return res;

	if (ts->cache.version)
	printf(DRV_NAME ": v%u loaded from 0x%08x\n",
	(unsigned)ts->cache.version, (unsigned)ts->offset);

	/* "enable" it */
	__ts = ts;

	return res;
	}