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261 lines
6.7 KiB
261 lines
6.7 KiB
From bec69bb8e85151729014d859106dcc3fe652b1d4 Mon Sep 17 00:00:00 2001
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From: Boris BREZILLON <boris.brezillon@free-electrons.com>
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Date: Mon, 28 Jul 2014 14:45:40 +0200
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Subject: [PATCH] mtd: nand: Add page status table (pst)
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Page status table is an byte array storing pages status.
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It defines 3 status:
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- unknown: the page has not been read yet and we do not know its current
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state
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- empty: the page contains only FFs
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- filled: the page has been filled with data
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Care must be taken: an empty page does not mean it can be written, because
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it might have already been written with only FFs.
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These page status are useful to check wether the controller should try to
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correct errors (using ECC) or a derandomize data (using a randomizer
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block).
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Signed-off-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
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Signed-off-by: Hans de Goede <hdegoede@redhat.com>
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---
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drivers/mtd/nand/nand_base.c | 154 +++++++++++++++++++++++++++++++++++++++++++
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include/linux/mtd/nand.h | 21 ++++++
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2 files changed, 175 insertions(+)
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--- a/drivers/mtd/nand/nand_base.c
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+++ b/drivers/mtd/nand/nand_base.c
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@@ -1102,6 +1102,138 @@ out:
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EXPORT_SYMBOL(nand_lock);
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/**
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+ * nand_page_is_empty - check wether a NAND page contains only FFs
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+ * @mtd: mtd info
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+ * @data: data buffer
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+ * @oob: oob buffer
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+ *
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+ * Reads the data stored in the databuf buffer and check if it contains only
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+ * FFs.
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+ *
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+ * Return true if it does else return false.
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+ */
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+bool nand_page_is_empty(struct mtd_info *mtd, void *data, void *oob)
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+{
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+ u8 *buf;
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+ int length;
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+ u32 pattern = 0xffffffff;
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+ int bitflips = 0;
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+ int cnt;
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+
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+ buf = data;
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+ length = mtd->writesize;
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+ while (length) {
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+ cnt = length < sizeof(pattern) ? length : sizeof(pattern);
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+ if (memcmp(&pattern, buf, cnt)) {
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+ int i;
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+ for (i = 0; i < cnt * BITS_PER_BYTE; i++) {
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+ if (!(buf[i / BITS_PER_BYTE] &
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+ (1 << (i % BITS_PER_BYTE)))) {
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+ bitflips++;
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+ if (bitflips > mtd->ecc_strength)
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+ return false;
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+ }
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+ }
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+ }
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+
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+ buf += sizeof(pattern);
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+ length -= sizeof(pattern);
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+ }
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+
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+ buf = oob;
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+ length = mtd->oobsize;
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+ while (length) {
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+ cnt = length < sizeof(pattern) ? length : sizeof(pattern);
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+ if (memcmp(&pattern, buf, cnt)) {
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+ int i;
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+ for (i = 0; i < cnt * BITS_PER_BYTE; i++) {
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+ if (!(buf[i / BITS_PER_BYTE] &
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+ (1 << (i % BITS_PER_BYTE)))) {
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+ bitflips++;
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+ if (bitflips > mtd->ecc_strength)
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+ return false;
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+ }
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+ }
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+ }
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+
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+ buf += sizeof(pattern);
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+ length -= sizeof(pattern);
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+ }
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+
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+ return true;
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+}
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+EXPORT_SYMBOL(nand_page_is_empty);
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+
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+/**
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+ * nand_page_get_status - retrieve page status from the page status table (pst)
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+ * @mtd: mtd info
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+ * @page: page you want to get status on
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+ *
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+ * Return the page status.
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+ */
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+int nand_page_get_status(struct mtd_info *mtd, int page)
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+{
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+ struct nand_chip *chip = mtd->priv;
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+ u8 shift = (page % 4) * 2;
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+ uint64_t offset = page / 4;
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+ int ret = NAND_PAGE_STATUS_UNKNOWN;
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+
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+ if (chip->pst)
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+ ret = (chip->pst[offset] >> shift) & 0x3;
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+
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+ return ret;
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+}
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+EXPORT_SYMBOL(nand_page_get_status);
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+
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+/**
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+ * nand_page_set_status - assign page status from in the page status table
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+ * @mtd: mtd info
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+ * @page: page you want to get status on
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+ * @status: new status to assign
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+ */
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+void nand_page_set_status(struct mtd_info *mtd, int page,
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+ enum nand_page_status status)
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+{
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+ struct nand_chip *chip = mtd->priv;
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+ u8 shift;
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+ uint64_t offset;
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+
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+ if (!chip->pst)
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+ return;
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+
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+ shift = (page % 4) * 2;
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+ offset = page / 4;
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+ chip->pst[offset] &= ~(0x3 << shift);
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+ chip->pst[offset] |= (status & 0x3) << shift;
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+}
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+EXPORT_SYMBOL(nand_page_set_status);
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+
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+/**
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+ * nand_pst_create - create a page status table
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+ * @mtd: mtd info
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+ *
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+ * Allocate a page status table and assign it to the mtd device.
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+ *
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+ * Returns 0 in case of success or -ERRNO in case of error.
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+ */
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+int nand_pst_create(struct mtd_info *mtd)
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+{
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+ struct nand_chip *chip = mtd->priv;
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+
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+ if (chip->pst)
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+ return 0;
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+
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+ chip->pst = kzalloc(mtd->size >>
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+ (chip->page_shift + mtd->subpage_sft + 2),
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+ GFP_KERNEL);
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+ if (!chip->pst)
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+ return -ENOMEM;
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+
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+ return 0;
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+}
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+EXPORT_SYMBOL(nand_pst_create);
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+
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+/**
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* nand_read_page_raw - [INTERN] read raw page data without ecc
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* @mtd: mtd info structure
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* @chip: nand chip info structure
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@@ -2539,6 +2671,7 @@ static int nand_do_write_ops(struct mtd_
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uint8_t *wbuf = buf;
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int use_bufpoi;
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int part_pagewr = (column || writelen < (mtd->writesize - 1));
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+ int subpage;
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if (part_pagewr)
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use_bufpoi = 1;
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@@ -2574,6 +2707,14 @@ static int nand_do_write_ops(struct mtd_
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if (ret)
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break;
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+ for (subpage = column / chip->subpagesize;
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+ subpage < (column + writelen) / chip->subpagesize;
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+ subpage++)
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+ nand_page_set_status(mtd,
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+ (page << mtd->subpage_sft) +
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+ subpage,
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+ NAND_PAGE_FILLED);
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+
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writelen -= bytes;
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if (!writelen)
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break;
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@@ -2979,6 +3120,7 @@ int nand_erase_nand(struct mtd_info *mtd
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int page, status, pages_per_block, ret, chipnr;
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struct nand_chip *chip = mtd->priv;
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loff_t len;
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+ int i;
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pr_debug("%s: start = 0x%012llx, len = %llu\n",
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__func__, (unsigned long long)instr->addr,
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@@ -3051,6 +3193,18 @@ int nand_erase_nand(struct mtd_info *mtd
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goto erase_exit;
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}
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+ for (i = 0; i < pages_per_block; i++) {
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+ int subpage;
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+ for (subpage = 0;
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+ subpage < 1 << mtd->subpage_sft;
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+ subpage++) {
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+ nand_page_set_status(mtd,
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+ ((page + i) << mtd->subpage_sft) +
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+ subpage,
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+ NAND_PAGE_EMPTY);
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+ }
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+ }
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+
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/* Increment page address and decrement length */
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len -= (1ULL << chip->phys_erase_shift);
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page += pages_per_block;
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--- a/include/linux/mtd/nand.h
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+++ b/include/linux/mtd/nand.h
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@@ -521,6 +521,24 @@ struct nand_ecc_ctrl {
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int page);
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};
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+/*
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+ * Constants for page status
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+ */
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+enum nand_page_status {
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+ NAND_PAGE_STATUS_UNKNOWN,
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+ NAND_PAGE_EMPTY,
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+ NAND_PAGE_FILLED,
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+};
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+
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+bool nand_page_is_empty(struct mtd_info *mtd, void *data, void *oob);
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+
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+int nand_page_get_status(struct mtd_info *mtd, int page);
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+
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+void nand_page_set_status(struct mtd_info *mtd, int page,
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+ enum nand_page_status status);
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+
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+int nand_pst_create(struct mtd_info *mtd);
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+
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/**
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* struct nand_buffers - buffer structure for read/write
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* @ecccalc: buffer pointer for calculated ECC, size is oobsize.
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@@ -630,6 +648,7 @@ struct nand_buffers {
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* @bbt_md: [REPLACEABLE] bad block table mirror descriptor
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* @badblock_pattern: [REPLACEABLE] bad block scan pattern used for initial
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* bad block scan.
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+ * @pst: [INTERN] page status table
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* @controller: [REPLACEABLE] a pointer to a hardware controller
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* structure which is shared among multiple independent
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* devices.
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@@ -718,6 +737,8 @@ struct nand_chip {
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struct nand_bbt_descr *badblock_pattern;
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+ uint8_t *pst;
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+
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struct list_head partitions;
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struct mutex part_lock;
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