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mtd: nand: Wait tCCS after a column change 

Drivers implementing ->cmd_ctrl() and relying on the default ->cmdfunc()
implementation usually don't wait tCCS when a column change (RNDIN or
RNDOUT) is requested.
Add an option flag to ask the core to do so (note that we keep this as
an opt-in to avoid breaking existing implementations), and make use of
the ->data_interface information is available (otherwise, wait 500ns).

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Tested-by: Marc Gonzalez <marc_gonzalez@sigmadesigns.com>
This commit is contained in:
Boris Brezillon 2016-10-01 10:24:03 +02:00
parent 204e7ecd47
commit 6ea40a3ba9
2 changed files with 35 additions and 1 deletions
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26
drivers/mtd/nand/nand_base.c
View File

@ -709,6 +709,25 @@ static void nand_command(struct mtd_info *mtd, unsigned int command,
nand_wait_ready(mtd);
}
static void nand_ccs_delay(struct nand_chip *chip)
{
/*
* The controller already takes care of waiting for tCCS when the RNDIN
* or RNDOUT command is sent, return directly.
*/
if (!(chip->options & NAND_WAIT_TCCS))
return;
/*
* Wait tCCS_min if it is correctly defined, otherwise wait 500ns
* (which should be safe for all NANDs).
*/
if (chip->data_interface && chip->data_interface->timings.sdr.tCCS_min)
ndelay(chip->data_interface->timings.sdr.tCCS_min / 1000);
else
ndelay(500);
}
/**
* nand_command_lp - [DEFAULT] Send command to NAND large page device
* @mtd: MTD device structure
@ -773,10 +792,13 @@ static void nand_command_lp(struct mtd_info *mtd, unsigned int command,
case NAND_CMD_ERASE1:
case NAND_CMD_ERASE2:
case NAND_CMD_SEQIN:
case NAND_CMD_RNDIN:
case NAND_CMD_STATUS:
return;
case NAND_CMD_RNDIN:
nand_ccs_delay(chip);
return;
case NAND_CMD_RESET:
if (chip->dev_ready)
break;
@ -795,6 +817,8 @@ static void nand_command_lp(struct mtd_info *mtd, unsigned int command,
NAND_NCE | NAND_CLE | NAND_CTRL_CHANGE);
chip->cmd_ctrl(mtd, NAND_CMD_NONE,
NAND_NCE | NAND_CTRL_CHANGE);
nand_ccs_delay(chip);
return;
case NAND_CMD_READ0:

10
include/linux/mtd/nand.h
View File

@ -210,6 +210,16 @@ enum nand_ecc_algo {
*/
#define NAND_USE_BOUNCE_BUFFER 0x00100000
/*
* In case your controller is implementing ->cmd_ctrl() and is relying on the
* default ->cmdfunc() implementation, you may want to let the core handle the
* tCCS delay which is required when a column change (RNDIN or RNDOUT) is
* requested.
* If your controller already takes care of this delay, you don't need to set
* this flag.
*/
#define NAND_WAIT_TCCS 0x00200000
/* Options set by nand scan */
/* Nand scan has allocated controller struct */
#define NAND_CONTROLLER_ALLOC 0x80000000