[U-Boot] [RFC 04/11] mtd/nand: add page status table (pst)

Roy Spliet
2015-06-05T11:52:37Z

From: yassin <yassinjaffer@gmail.com>

Signed-off-by: Roy Spliet <r.spliet@ultimaker.com>
---
drivers/mtd/nand/nand_base.c | 154 +++++++++++++++++++++++++++++++++++++++++++
include/linux/mtd/nand.h | 21 ++++++
2 files changed, 175 insertions(+)

diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index dbeb092..1c514a0 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -1185,6 +1185,138 @@ EXPORT_SYMBOL(nand_lock);
#endif

/**
+ * nand_page_is_empty - check wether a NAND page contains only FFs
+ * @mtd: mtd info
+ * @data: data buffer
+ * @oob: oob buffer
+ *
+ * Reads the data stored in the databuf buffer and check if it contains only
+ * FFs.
+ *
+ * Return true if it does else return false.
+ */
+bool nand_page_is_empty(struct mtd_info *mtd, void *data, void *oob)
+{
+ u8 *buf;
+ int length;
+ u32 pattern = 0xffffffff;
+ int bitflips = 0;
+ int cnt;
+
+ buf = data;
+ length = mtd->writesize;
+ while (length) {
+ cnt = length < sizeof(pattern) ? length : sizeof(pattern);
+ if (memcmp(&pattern, buf, cnt)) {
+ int i;
+ for (i = 0; i < cnt * 8; i++) {
+ if (!(buf[i / 8] &
+ (1 << (i % 8)))) {
+ bitflips++;
+ if (bitflips > mtd->ecc_strength)
+ return false;
+ }
+ }
+ }
+
+ buf += sizeof(pattern);
+ length -= sizeof(pattern);
+ }
+
+ buf = oob;
+ length = mtd->oobsize;
+ while (length) {
+ cnt = length < sizeof(pattern) ? length : sizeof(pattern);
+ if (memcmp(&pattern, buf, cnt)) {
+ int i;
+ for (i = 0; i < cnt * 8; i++) {
+ if (!(buf[i / 8] &
+ (1 << (i % 8)))) {
+ bitflips++;
+ if (bitflips > mtd->ecc_strength)
+ return false;
+ }
+ }
+ }
+
+ buf += sizeof(pattern);
+ length -= sizeof(pattern);
+ }
+
+ return true;
+}
+EXPORT_SYMBOL(nand_page_is_empty);
+
+/**
+ * nand_page_get_status - retrieve page status from the page status table (pst)
+ * @mtd: mtd info
+ * @page: page you want to get status on
+ *
+ * Return the page status.
+ */
+int nand_page_get_status(struct mtd_info *mtd, int page)
+{
+ struct nand_chip *chip = mtd->priv;
+ u8 shift = (page % 4) * 2;
+ uint64_t offset = page / 4;
+ int ret = NAND_PAGE_STATUS_UNKNOWN;
+
+ if (chip->pst)
+ ret = (chip->pst[offset] >> shift) & 0x3;
+
+ return ret;
+}
+EXPORT_SYMBOL(nand_page_get_status);
+
+/**
+ * nand_page_set_status - assign page status from in the page status table
+ * @mtd: mtd info
+ * @page: page you want to get status on
+ * @status: new status to assign
+ */
+void nand_page_set_status(struct mtd_info *mtd, int page,
+ enum nand_page_status status)
+{
+ struct nand_chip *chip = mtd->priv;
+ u8 shift;
+ uint64_t offset;
+
+ if (!chip->pst)
+ return;
+
+ shift = (page % 4) * 2;
+ offset = page / 4;
+ chip->pst[offset] &= ~(0x3 << shift);
+ chip->pst[offset] |= (status & 0x3) << shift;
+}
+EXPORT_SYMBOL(nand_page_set_status);
+
+/**
+ * nand_pst_create - create a page status table
+ * @mtd: mtd info
+ *
+ * Allocate a page status table and assign it to the mtd device.
+ *
+ * Returns 0 in case of success or -ERRNO in case of error.
+ */
+int nand_pst_create(struct mtd_info *mtd)
+{
+ struct nand_chip *chip = mtd->priv;
+
+ if (chip->pst)
+ return 0;
+
+ chip->pst = kzalloc(mtd->size >>
+ (chip->page_shift + mtd->subpage_sft + 2),
+ GFP_KERNEL);
+ if (!chip->pst)
+ return -ENOMEM;
+
+ return 0;
+}
+EXPORT_SYMBOL(nand_pst_create);
+
+/**
* nand_read_page_raw - [INTERN] read raw page data without ecc
* @mtd: mtd info structure
* @chip: nand chip info structure
@@ -2521,6 +2653,7 @@ static int nand_do_write_ops(struct mtd_info *mtd, loff_t to,
int bytes = mtd->writesize;
int cached = writelen > bytes && page != blockmask;
uint8_t *wbuf = buf;
+ int subpage;

WATCHDOG_RESET();
/* Partial page write? */
@@ -2547,6 +2680,14 @@ static int nand_do_write_ops(struct mtd_info *mtd, loff_t to,
if (ret)
break;

+ for (subpage = column / chip->subpagesize;
+ subpage < (column + writelen) / chip->subpagesize;
+ subpage++)
+ nand_page_set_status(mtd,
+ (page << mtd->subpage_sft) +
+ subpage,
+ NAND_PAGE_FILLED);
+
writelen -= bytes;
if (!writelen)
break;
@@ -2804,6 +2945,7 @@ int nand_erase_nand(struct mtd_info *mtd, struct erase_info *instr,
int page, status, pages_per_block, ret, chipnr;
struct nand_chip *chip = mtd->priv;
loff_t len;
+ int i;

pr_debug("%s: start = 0x%012llx, len = %llu\n",
__func__, (unsigned long long)instr->addr,
@@ -2880,6 +3022,18 @@ int nand_erase_nand(struct mtd_info *mtd, struct erase_info *instr,
goto erase_exit;
}

+ for (i = 0; i < pages_per_block; i++) {
+ int subpage;
+ for (subpage = 0;
+ subpage < 1 << mtd->subpage_sft;
+ subpage++) {
+ nand_page_set_status(mtd,
+ ((page + i) << mtd->subpage_sft) +
+ subpage,
+ NAND_PAGE_EMPTY);
+ }
+ }
+
/* Increment page address and decrement length */
len -= (1ULL << chip->phys_erase_shift);
page += pages_per_block;
diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h
index 0cdb3b9..ef6a783 100644
--- a/include/linux/mtd/nand.h
+++ b/include/linux/mtd/nand.h
@@ -547,6 +547,24 @@ struct nand_ecc_ctrl {
int page);
};

+/*
+ * Constants for page status
+ */
+enum nand_page_status {
+ NAND_PAGE_STATUS_UNKNOWN,
+ NAND_PAGE_EMPTY,
+ NAND_PAGE_FILLED,
+};
+
+bool nand_page_is_empty(struct mtd_info *mtd, void *data, void *oob);
+
+int nand_page_get_status(struct mtd_info *mtd, int page);
+
+void nand_page_set_status(struct mtd_info *mtd, int page,
+ enum nand_page_status status);
+
+int nand_pst_create(struct mtd_info *mtd);
+
/**
* struct nand_buffers - buffer structure for read/write
* @ecccalc: buffer pointer for calculated ECC, size is oobsize.
@@ -660,6 +678,7 @@ struct nand_buffers {
* @bbt_md: [REPLACEABLE] bad block table mirror descriptor
* @badblock_pattern: [REPLACEABLE] bad block scan pattern used for initial
* bad block scan.
+ * @pst: [INTERN] page status table
* @controller: [REPLACEABLE] a pointer to a hardware controller
* structure which is shared among multiple independent
* devices.
@@ -750,6 +769,8 @@ struct nand_chip {

struct nand_bbt_descr *badblock_pattern;

+ uint8_t *pst;
+
void *priv;
};

--
2.4.2

--

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