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

Roy Spliet r.spliet at ultimaker.com
Fri Jun 5 13:52:37 CEST 2015


From: yassin <yassinjaffer at gmail.com>

Signed-off-by: Roy Spliet <r.spliet at 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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