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NAND: Add timeout for reset command

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Without the timeout present an infinite loop can occur if the
NAND device is broken or not present.

Signed-off-by: Peter Tyser <ptyser@xes-inc.com>
Signed-off-by: Scott Wood <scottwood@freescale.com>
This commit is contained in:
Peter Tyser 2009-02-04 13:47:22 -06:00 committed by Scott Wood
parent 10dc6a9bef
commit 8da601280a
1 changed files with 17 additions and 2 deletions
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19
drivers/mtd/nand/nand_base.c
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@ -75,6 +75,17 @@
#include <jffs2/jffs2.h>
#endif
/*
* CONFIG_SYS_NAND_RESET_CNT is used as a timeout mechanism when resetting
* a flash. NAND flash is initialized prior to interrupts so standard timers
* can't be used. CONFIG_SYS_NAND_RESET_CNT should be set to a value
* which is greater than (max NAND reset time / NAND status read time).
* A conservative default of 200000 (500 us / 25 ns) is used as a default.
*/
#ifndef CONFIG_SYS_NAND_RESET_CNT
#define CONFIG_SYS_NAND_RESET_CNT 200000
#endif
/* Define default oob placement schemes for large and small page devices */
static struct nand_ecclayout nand_oob_8 = {
.eccbytes = 3,
@ -524,6 +535,7 @@ static void nand_command(struct mtd_info *mtd, unsigned int command,
{
register struct nand_chip *chip = mtd->priv;
int ctrl = NAND_CTRL_CLE | NAND_CTRL_CHANGE;
uint32_t rst_sts_cnt = CONFIG_SYS_NAND_RESET_CNT;
/*
* Write out the command to the device.
@ -590,7 +602,8 @@ static void nand_command(struct mtd_info *mtd, unsigned int command,
NAND_CTRL_CLE | NAND_CTRL_CHANGE);
chip->cmd_ctrl(mtd,
NAND_CMD_NONE, NAND_NCE | NAND_CTRL_CHANGE);
while (!(chip->read_byte(mtd) & NAND_STATUS_READY)) ;
while (!(chip->read_byte(mtd) & NAND_STATUS_READY) &&
(rst_sts_cnt--));
return;
/* This applies to read commands */
@ -626,6 +639,7 @@ static void nand_command_lp(struct mtd_info *mtd, unsigned int command,
int column, int page_addr)
{
register struct nand_chip *chip = mtd->priv;
uint32_t rst_sts_cnt = CONFIG_SYS_NAND_RESET_CNT;
/* Emulate NAND_CMD_READOOB */
if (command == NAND_CMD_READOOB) {
@ -696,7 +710,8 @@ 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);
while (!(chip->read_byte(mtd) & NAND_STATUS_READY)) ;
while (!(chip->read_byte(mtd) & NAND_STATUS_READY) &&
(rst_sts_cnt--));
return;
case NAND_CMD_RNDOUT: