NAND: Add timeout for reset command
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>
diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
index bfa7874..d33fee2 100644
--- a/drivers/mtd/nand/nand_base.c
+++ b/drivers/mtd/nand/nand_base.c
@@ -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 @@
{
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 @@
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 @@
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 @@
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: