From: Adrian Hunter Date: Thu, 4 Jan 2007 09:51:26 +0200 Subject: [MTD] OneNand: Implement read-while-load Read-while-load enables higher performance read operations. Signed-off-by: Adrian Hunter --- drivers/mtd/onenand/onenand_base.c | 46 ++++++++++++++++++++++-------------- include/linux/mtd/onenand.h | 1 + 2 files changed, 29 insertions(+), 18 deletions(-) diff --git a/drivers/mtd/onenand/onenand_base.c b/drivers/mtd/onenand/onenand_base.c index e121bcc..11da796 100644 --- a/drivers/mtd/onenand/onenand_base.c +++ b/drivers/mtd/onenand/onenand_base.c @@ -727,38 +727,45 @@ static int onenand_read(struct mtd_info /* TODO handling oob */ stats = mtd->ecc_stats; - while (read < len) { - thislen = min_t(int, mtd->writesize, len - read); - column = from & (mtd->writesize - 1); - if (column + thislen > mtd->writesize) - thislen = mtd->writesize - column; + /* Read-while-load method */ + /* Do first load to bufferRAM */ + if (read < len) { if (!onenand_check_bufferram(mtd, from)) { this->command(mtd, ONENAND_CMD_READ, from, mtd->writesize); - ret = this->wait(mtd, FL_READING); - /* First copy data and check return value for ECC handling */ onenand_update_bufferram(mtd, from, !ret); } - - this->read_bufferram(mtd, ONENAND_DATARAM, buf, column, thislen); - - if (ret) { - DEBUG(MTD_DEBUG_LEVEL0, "onenand_read: read failed = %d\n", ret); - goto out; + } + thislen = min_t(int, mtd->writesize, len - read); + column = from & (mtd->writesize - 1); + if (column + thislen > mtd->writesize) + thislen = mtd->writesize - column; + while (!ret) { + /* If there is more to load then start next load */ + from += thislen; + if (read + thislen < len) { + this->command(mtd, ONENAND_CMD_READ, from, mtd->writesize); + ONENAND_SET_PREV_BUFFERRAM(this); } - + /* While load is going, read from last bufferRAM */ + this->read_bufferram(mtd, ONENAND_DATARAM, buf, column, thislen); + /* See if we are done */ read += thislen; - if (read == len) break; - - from += thislen; + /* Set up for next read from bufferRAM */ + ONENAND_SET_NEXT_BUFFERRAM(this); buf += thislen; + thislen = min_t(int, mtd->writesize, len - read); + column = 0; + cond_resched(); + /* Now wait for load */ + ret = this->wait(mtd, FL_READING); + onenand_update_bufferram(mtd, from, !ret); } -out: /* Deselect and wake up anyone waiting on the device */ onenand_release_device(mtd); @@ -772,6 +779,9 @@ out: if (mtd->ecc_stats.failed - stats.failed) return -EBADMSG; + if (ret) + return ret; + return mtd->ecc_stats.corrected - stats.corrected ? -EUCLEAN : 0; } diff --git a/include/linux/mtd/onenand.h b/include/linux/mtd/onenand.h index fe3500d..f775a7a 100644 --- a/include/linux/mtd/onenand.h +++ b/include/linux/mtd/onenand.h @@ -143,6 +143,7 @@ struct onenand_chip { #define ONENAND_CURRENT_BUFFERRAM(this) (this->bufferram_index) #define ONENAND_NEXT_BUFFERRAM(this) (this->bufferram_index ^ 1) #define ONENAND_SET_NEXT_BUFFERRAM(this) (this->bufferram_index ^= 1) +#define ONENAND_SET_PREV_BUFFERRAM(this) (this->bufferram_index ^= 1) #define ONENAND_GET_SYS_CFG1(this) \ (this->read_word(this->base + ONENAND_REG_SYS_CFG1)) -- 1.4.3