Messages in this thread Patch in this message | | | From | Boris Brezillon <> | Subject | [PATCH 1/5] mtd: nand: add basic stuff to support power-cut emulation | Date | Fri, 25 Sep 2015 17:09:14 +0200 |
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Add a new status flag to support power-cut emulation. Since real NAND status is limited to 8bits, we can safely use higher bits for something else. The NAND_STATUS_POWER_CUT is assigned bit 30 to avoid integer overflow (not sure this is necessary).
The NAND status is currently retrieved using ->read_byte() after sending a NAND_CMD_STATUS command, which prevents the nandsim (or any other implementation that wants to support power-cut emulation) to return a value with the NAND_STATUS_POWER_CUT flag set. Add a ->get_status() method returning an int, and provide a default implementation.
Also note that ->get_status() could be used for other cases than power-cut emulation. For example, some NAND controllers are able to retrieve the NAND status by their own after launching a specific command, and this status is then stored in a specific register, thus preventing the extra ->cmdfunc() + ->read_byte() calls.
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com> --- drivers/mtd/nand/nand_base.c | 17 ++++++++++++++--- include/linux/mtd/nand.h | 4 ++++ 2 files changed, 18 insertions(+), 3 deletions(-)
diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c index 37c0d9d..a621814 100644 --- a/drivers/mtd/nand/nand_base.c +++ b/drivers/mtd/nand/nand_base.c @@ -478,8 +478,7 @@ static int nand_check_wp(struct mtd_info *mtd) return 0; /* Check the WP bit */ - chip->cmdfunc(mtd, NAND_CMD_STATUS, -1, -1); - return (chip->read_byte(mtd) & NAND_STATUS_WP) ? 0 : 1; + return (chip->get_status(mtd) & NAND_STATUS_WP) ? 0 : 1; } /** @@ -880,6 +879,15 @@ static void panic_nand_wait(struct mtd_info *mtd, struct nand_chip *chip, } } +static int nand_get_status(struct mtd_info *mtd) +{ + struct nand_chip *chip = mtd->priv; + + chip->cmdfunc(mtd, NAND_CMD_STATUS, -1, -1); + + return (int)chip->read_byte(mtd); +} + /** * nand_wait - [DEFAULT] wait until the command is done * @mtd: MTD device structure @@ -922,7 +930,7 @@ static int nand_wait(struct mtd_info *mtd, struct nand_chip *chip) } led_trigger_event(nand_led_trigger, LED_OFF); - status = (int)chip->read_byte(mtd); + status = chip->get_status(mtd); /* This can happen if in case of timeout or buggy dev_ready */ WARN_ON(!(status & NAND_STATUS_READY)); return status; @@ -3106,6 +3114,9 @@ static void nand_set_defaults(struct nand_chip *chip, int busw) if (chip->cmdfunc == NULL) chip->cmdfunc = nand_command; + if (!chip->get_status) + chip->get_status = nand_get_status; + /* check, if a user supplied wait function given */ if (chip->waitfunc == NULL) chip->waitfunc = nand_wait; diff --git a/include/linux/mtd/nand.h b/include/linux/mtd/nand.h index c4d8e30..075d7b8 100644 --- a/include/linux/mtd/nand.h +++ b/include/linux/mtd/nand.h @@ -107,6 +107,9 @@ extern int nand_unlock(struct mtd_info *mtd, loff_t ofs, uint64_t len); #define NAND_STATUS_READY 0x40 #define NAND_STATUS_WP 0x80 +/* Status bits reserved for NAND emulation */ +#define NAND_STATUS_POWER_CUT 0x40000000 + /* * Constants for ECC_MODES */ @@ -661,6 +664,7 @@ struct nand_chip { int (*init_size)(struct mtd_info *mtd, struct nand_chip *this, u8 *id_data); int (*dev_ready)(struct mtd_info *mtd); + int (*get_status)(struct mtd_info *mtd); void (*cmdfunc)(struct mtd_info *mtd, unsigned command, int column, int page_addr); int(*waitfunc)(struct mtd_info *mtd, struct nand_chip *this); -- 1.9.1
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