Hello.
Thought it's worth forwarding this here...
-------- Original Message --------
Subject: mtd/drivers/mtd/nand au1550nd.c,1.13,1.14
Date: Sun, 13 Nov 2005 09:52:10 +0000
From: ppopov@xxxxxxxxxxxxx
To: linux-mtd-cvs@xxxxxxxxxxxxxxxxxxx
Update of /home/cvs/mtd/drivers/mtd/nand
In directory phoenix.infradead.org:/tmp/cvs-serv4485/drivers/mtd/nand
Modified Files:
au1550nd.c
Log Message:
1. MEM_STNDCTL is write only.
2. Patch for problem with static bus controller which fails to keep
CE asserted during chip ready delay on read commands. The problem was
documented by Sergei Shtylylov; patch by the same author.
Index: au1550nd.c
===================================================================
RCS file: /home/cvs/mtd/drivers/mtd/nand/au1550nd.c,v
retrieving revision 1.13
retrieving revision 1.14
diff -u -r1.13 -r1.14
--- au1550nd.c 7 Nov 2005 11:14:30 -0000 1.13
+++ au1550nd.c 13 Nov 2005 09:52:07 -0000 1.14
@@ -14,9 +14,11 @@
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/module.h>
+#include <linux/interrupt.h>
#include <linux/mtd/mtd.h>
#include <linux/mtd/nand.h>
#include <linux/mtd/partitions.h>
+#include <linux/version.h>
#include <asm/io.h>
/* fixme: this is ugly */
@@ -313,6 +315,141 @@
return ret;
}
+/**
+ * au1550_select_chip - control -CE line
+ * Forbid driving -CE manually permitting the NAND controller to do this.
+ * Keeping -CE asserted during the whole sector reads interferes with the
+ * NOR flash and PCMCIA drivers as it causes contention on the static bus.
+ * We only have to hold -CE low for the NAND read commands since the flash
+ * chip needs it to be asserted during chip not ready time but the NAND
+ * controller keeps it released.
+ *
+ * @mtd: MTD device structure
+ * @chip: chipnumber to select, -1 for deselect
+ */
+static void au1550_select_chip(struct mtd_info *mtd, int chip)
+{
+}
+
+/**
+ * au1550_command - Send command to NAND device
+ * @mtd: MTD device structure
+ * @command: the command to be sent
+ * @column: the column address for this command, -1 if none
+ * @page_addr: the page address for this command, -1 if none
+ */
+static void au1550_command(struct mtd_info *mtd, unsigned command, int
column, int page_addr)
+{
+ register struct nand_chip *this = mtd->priv;
+ int ce_override = 0, i;
+ ulong flags;
+
+ /* Begin command latch cycle */
+ this->hwcontrol(mtd, NAND_CTL_SETCLE);
+ /*
+ * Write out the command to the device.
+ */
+ if (command == NAND_CMD_SEQIN) {
+ int readcmd;
+
+ if (column >= mtd->oobblock) {
+ /* OOB area */
+ column -= mtd->oobblock;
+ readcmd = NAND_CMD_READOOB;
+ } else if (column < 256) {
+ /* First 256 bytes --> READ0 */
+ readcmd = NAND_CMD_READ0;
+ } else {
+ column -= 256;
+ readcmd = NAND_CMD_READ1;
+ }
+ this->write_byte(mtd, readcmd);
+ }
+ this->write_byte(mtd, command);
+
+ /* Set ALE and clear CLE to start address cycle */
+ this->hwcontrol(mtd, NAND_CTL_CLRCLE);
+
+ if (column != -1 || page_addr != -1) {
+ this->hwcontrol(mtd, NAND_CTL_SETALE);
+
+ /* Serially input address */
+ if (column != -1) {
+ /* Adjust columns for 16 bit buswidth */
+ if (this->options & NAND_BUSWIDTH_16)
+ column >>= 1;
+ this->write_byte(mtd, column);
+ }
+ if (page_addr != -1) {
+ this->write_byte(mtd, (u8)(page_addr & 0xff));
+
+ if (command == NAND_CMD_READ0 ||
+ command == NAND_CMD_READ1 ||
+ command == NAND_CMD_READOOB) {
+ /*
+ * NAND controller will release -CE after
+ * the last address byte is written, so we'll
+ * have to forcibly assert it. No interrupts
+ * are allowed while we do this as we don't
+ * want the NOR flash or PCMCIA drivers to
+ * steal our precious bytes of data...
+ */
+ ce_override = 1;
+ local_irq_save(flags);
+ this->hwcontrol(mtd, NAND_CTL_SETNCE);
+ }
+
+ this->write_byte(mtd, (u8)(page_addr >> 8));
+
+ /* One more address cycle for devices > 32MiB */
+ if (this->chipsize > (32 << 20))
+ this->write_byte(mtd, (u8)((page_addr >> 16) & 0x0f));
+ }
+ /* Latch in address */
+ this->hwcontrol(mtd, NAND_CTL_CLRALE);
+ }
+
+ /*
+ * Program and erase have their own busy handlers.
+ * Status and sequential in need no delay.
+ */
+ switch (command) {
+
+ case NAND_CMD_PAGEPROG:
+ case NAND_CMD_ERASE1:
+ case NAND_CMD_ERASE2:
+ case NAND_CMD_SEQIN:
+ case NAND_CMD_STATUS:
+ return;
+
+ case NAND_CMD_RESET:
+ break;
+
+ case NAND_CMD_READ0:
+ case NAND_CMD_READ1:
+ case NAND_CMD_READOOB:
+ /* Check if we're really driving -CE low (just in case) */
+ if (unlikely(!ce_override))
+ break;
+
+ /* Apply a short delay always to ensure that we do wait tWB. */
+ ndelay(100);
+ /* Wait for a chip to become ready... */
+ for (i = this->chip_delay; !this->dev_ready(mtd) && i > 0; --i)
+ udelay(1);
+
+ /* Release -CE and re-enable interrupts. */
+ this->hwcontrol(mtd, NAND_CTL_CLRNCE);
+ local_irq_restore(flags);
+ return;
+ }
+ /* Apply this short delay always to ensure that we do wait tWB. */
+ ndelay(100);
+
+ while(!this->dev_ready(mtd));
+}
+
+
/*
* Main initialization routine
*/
@@ -342,12 +479,8 @@
/* Link the private data with the MTD structure */
au1550_mtd->priv = this;
-
- /* disable interrupts */
- au_writel(au_readl(MEM_STNDCTL) & ~(1<<8), MEM_STNDCTL);
-
- /* disable NAND boot */
- au_writel(au_readl(MEM_STNDCTL) & ~(1<<0), MEM_STNDCTL);
+ /* MEM_STNDCTL: disable ints, disable nand boot */
+ au_writel(0, MEM_STNDCTL);
#ifdef CONFIG_MIPS_PB1550
/* set gpio206 high */
@@ -437,6 +570,9 @@
/* Set address of hardware control function */
this->hwcontrol = au1550_hwcontrol;
this->dev_ready = au1550_device_ready;
+ this->select_chip = au1550_select_chip;
+ this->cmdfunc = au1550_command;
+
/* 30 us command delay time */
this->chip_delay = 30;
this->eccmode = NAND_ECC_SOFT;
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