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Subject[RFC 43/47] mtd: nand: stm_nand_bch: read and write functions (BCH)
Date
Helper function for bch_mtd_read() and bch_mtd_write() to handle
multi-page or non-aligned reads and writes respectively.

Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
drivers/mtd/nand/stm_nand_bch.c | 143 ++++++++++++++++++++++++++++++++++++++++
1 file changed, 143 insertions(+)

diff --git a/drivers/mtd/nand/stm_nand_bch.c b/drivers/mtd/nand/stm_nand_bch.c
index 389ccee..bcaed32 100644
--- a/drivers/mtd/nand/stm_nand_bch.c
+++ b/drivers/mtd/nand/stm_nand_bch.c
@@ -507,6 +507,149 @@ static uint8_t bch_write_page(struct nandi_controller *nandi,
return status;
}

+/* Helper function for bch_mtd_read to handle multi-page or non-aligned reads */
+static int bch_read(struct nandi_controller *nandi,
+ loff_t from, size_t len,
+ size_t *retlen, u_char *buf)
+{
+ struct mtd_ecc_stats stats;
+ uint32_t page_size = nandi->info.mtd.writesize;
+ uint32_t col_offs;
+ loff_t page_mask;
+ loff_t page_offs;
+ int ecc_errs, max_ecc_errs = 0;
+ int page_num;
+ size_t bytes;
+ uint8_t *p;
+ bool bounce = false;
+
+ dev_dbg(nandi->dev, "%s: %llu @ 0x%012llx\n", __func__,
+ (unsigned long long)len, from);
+
+ stats = nandi->info.mtd.ecc_stats;
+ page_mask = (loff_t)page_size - 1;
+ col_offs = (uint32_t)(from & page_mask);
+ page_offs = from & ~page_mask;
+ page_num = (int)(page_offs >> nandi->page_shift);
+
+ while (len > 0) {
+ bytes = min((page_size - col_offs), len);
+
+ if ((bytes != page_size) ||
+ ((unsigned int)buf & (NANDI_BCH_DMA_ALIGNMENT - 1)) ||
+ (!virt_addr_valid(buf))) /* vmalloc'd buffer! */
+ bounce = true;
+
+ if (page_num == nandi->cached_page) {
+ memcpy(buf, nandi->page_buf + col_offs, bytes);
+ goto done;
+ }
+
+ p = bounce ? nandi->page_buf : buf;
+
+ ecc_errs = bch_read_page(nandi, page_offs, p);
+ if (bounce)
+ memcpy(buf, p + col_offs, bytes);
+
+ if (ecc_errs < 0) {
+ dev_err(nandi->dev,
+ "%s: uncorrectable error at 0x%012llx\n",
+ __func__, page_offs);
+ nandi->info.mtd.ecc_stats.failed++;
+
+ /* Do not cache uncorrectable pages */
+ if (bounce)
+ nandi->cached_page = -1;
+
+ goto done;
+ }
+
+ if (ecc_errs) {
+ dev_info(nandi->dev,
+ "%s: corrected %u error(s) at 0x%012llx\n",
+ __func__, ecc_errs, page_offs);
+
+ nandi->info.mtd.ecc_stats.corrected += ecc_errs;
+
+ if (ecc_errs > max_ecc_errs)
+ max_ecc_errs = ecc_errs;
+ }
+
+ if (bounce)
+ nandi->cached_page = page_num;
+
+done:
+ buf += bytes;
+ len -= bytes;
+
+ if (retlen)
+ *retlen += bytes;
+
+ /* We are now page-aligned */
+ page_offs += page_size;
+ page_num++;
+ col_offs = 0;
+ }
+
+ /* Return '-EBADMSG' on uncorrectable errors */
+ if (nandi->info.mtd.ecc_stats.failed - stats.failed)
+ return -EBADMSG;
+
+ return max_ecc_errs;
+}
+
+/* Helper function for mtd_write, to handle multi-page and non-aligned writes */
+static int bch_write(struct nandi_controller *nandi,
+ loff_t to, size_t len,
+ size_t *retlen, const uint8_t *buf)
+{
+ uint32_t page_size = nandi->info.mtd.writesize;
+ int page_num;
+ bool bounce = false;
+ const uint8_t *p = NULL;
+ uint8_t ret;
+
+ dev_dbg(nandi->dev, "%s: %llu @ 0x%012llx\n", __func__,
+ (unsigned long long)len, to);
+
+ BUG_ON(len & (page_size - 1));
+ BUG_ON(to & (page_size - 1));
+
+ if (((unsigned long)buf & (NANDI_BCH_DMA_ALIGNMENT - 1)) ||
+ !virt_addr_valid(buf)) { /* vmalloc'd buffer! */
+ bounce = true;
+ }
+
+ page_num = (int)(to >> nandi->page_shift);
+
+ while (len > 0) {
+ if (bounce) {
+ memcpy(nandi->page_buf, buf, page_size);
+ p = nandi->page_buf;
+ nandi->cached_page = -1;
+ } else {
+ p = buf;
+ }
+
+ if (nandi->cached_page == page_num)
+ nandi->cached_page = -1;
+
+ ret = bch_write_page(nandi, to, p);
+ if (ret & NAND_STATUS_FAIL)
+ return -EIO;
+
+ to += page_size;
+ page_num++;
+ buf += page_size;
+ len -= page_size;
+
+ if (retlen)
+ *retlen += page_size;
+ }
+
+ return 0;
+}
+
/*
* Hamming-FLEX operations
*/
--
1.8.3.2


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