mtd: mxc-nand: Allow to use column addresses different from 0

[Linux-MTD Mailing List]

Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=c4ca3997ef954bcba009cce0e325f3155bdde01a
Commit:     c4ca3997ef954bcba009cce0e325f3155bdde01a
Parent:     3f410690f511f9531fdc0865a931522b049d7b29
Author:     Uwe Kleine-König <u.kleine-koenig at pengutronix.de>
AuthorDate: Tue Feb 10 19:59:58 2015 +0100
Committer:  Brian Norris <computersforpeace at gmail.com>
CommitDate: Wed Mar 11 15:20:29 2015 -0700

    mtd: mxc-nand: Allow to use column addresses different from 0
    
    The mxc-nand controller works pagewise and so usually only sends
    commands to the flash chip with column == 0. A request with column != 0
    from the upper layer is then fulfilled by indexing appropriately into the
    device's RAM buffer.
    
    To be able to access the ONFI marker at offset 0x20 in reply to the
    READID command however it's invalid to read 32 bytes starting from
    column 0.
    
    So let the function used to send the address cycles send the column
    address actually passed instead of 0 and fix all callers to pass 0
    instead appropriately. Also add some warnings in case this patch changes
    the drivers semantics.
    
    Signed-off-by: Uwe Kleine-König <u.kleine-koenig at pengutronix.de>
    Signed-off-by: Brian Norris <computersforpeace at gmail.com>
---
 drivers/mtd/nand/mxc_nand.c | 40 +++++++++++++++++++++++++++++-----------
 1 file changed, 29 insertions(+), 11 deletions(-)

diff --git a/drivers/mtd/nand/mxc_nand.c b/drivers/mtd/nand/mxc_nand.c
index aa98a0d..0afe590 100644
--- a/drivers/mtd/nand/mxc_nand.c
+++ b/drivers/mtd/nand/mxc_nand.c
@@ -836,6 +836,12 @@ static void copy_spare(struct mtd_info *mtd, bool bfrom)
 	}
 }
 
+/*
+ * MXC NANDFC can only perform full page+spare or spare-only read/write.  When
+ * the upper layers perform a read/write buf operation, the saved column address
+ * is used to index into the full page. So usually this function is called with
+ * column == 0 (unless no column cycle is needed indicated by column == -1)
+ */
 static void mxc_do_addr_cycle(struct mtd_info *mtd, int column, int page_addr)
 {
 	struct nand_chip *nand_chip = mtd->priv;
@@ -843,16 +849,13 @@ static void mxc_do_addr_cycle(struct mtd_info *mtd, int column, int page_addr)
 
 	/* Write out column address, if necessary */
 	if (column != -1) {
-		/*
-		 * MXC NANDFC can only perform full page+spare or
-		 * spare-only read/write.  When the upper layers
-		 * perform a read/write buf operation, the saved column
-		  * address is used to index into the full page.
-		 */
-		host->devtype_data->send_addr(host, 0, page_addr == -1);
+		host->devtype_data->send_addr(host, column & 0xff,
+					      page_addr == -1);
 		if (mtd->writesize > 512)
 			/* another col addr cycle for 2k page */
-			host->devtype_data->send_addr(host, 0, false);
+			host->devtype_data->send_addr(host,
+						      (column >> 8) & 0xff,
+						      false);
 	}
 
 	/* Write out page address, if necessary */
@@ -1077,6 +1080,9 @@ static void mxc_nand_command(struct mtd_info *mtd, unsigned command,
 		host->status_request = true;
 
 		host->devtype_data->send_cmd(host, command, true);
+		WARN_ONCE(column != -1 || page_addr != -1,
+			  "Unexpected column/row value (cmd=%u, col=%d, row=%d)\n",
+			  command, column, page_addr);
 		mxc_do_addr_cycle(mtd, column, page_addr);
 		break;
 
@@ -1090,7 +1096,10 @@ static void mxc_nand_command(struct mtd_info *mtd, unsigned command,
 		command = NAND_CMD_READ0; /* only READ0 is valid */
 
 		host->devtype_data->send_cmd(host, command, false);
-		mxc_do_addr_cycle(mtd, column, page_addr);
+		WARN_ONCE(column < 0,
+			  "Unexpected column/row value (cmd=%u, col=%d, row=%d)\n",
+			  command, column, page_addr);
+		mxc_do_addr_cycle(mtd, 0, page_addr);
 
 		if (mtd->writesize > 512)
 			host->devtype_data->send_cmd(host,
@@ -1111,7 +1120,10 @@ static void mxc_nand_command(struct mtd_info *mtd, unsigned command,
 		host->buf_start = column;
 
 		host->devtype_data->send_cmd(host, command, false);
-		mxc_do_addr_cycle(mtd, column, page_addr);
+		WARN_ONCE(column < -1,
+			  "Unexpected column/row value (cmd=%u, col=%d, row=%d)\n",
+			  command, column, page_addr);
+		mxc_do_addr_cycle(mtd, 0, page_addr);
 		break;
 
 	case NAND_CMD_PAGEPROG:
@@ -1119,6 +1131,9 @@ static void mxc_nand_command(struct mtd_info *mtd, unsigned command,
 		copy_spare(mtd, false);
 		host->devtype_data->send_page(mtd, NFC_INPUT);
 		host->devtype_data->send_cmd(host, command, true);
+		WARN_ONCE(column != -1 || page_addr != -1,
+			  "Unexpected column/row value (cmd=%u, col=%d, row=%d)\n",
+			  command, column, page_addr);
 		mxc_do_addr_cycle(mtd, column, page_addr);
 		break;
 
@@ -1126,12 +1141,15 @@ static void mxc_nand_command(struct mtd_info *mtd, unsigned command,
 		host->devtype_data->send_cmd(host, command, true);
 		mxc_do_addr_cycle(mtd, column, page_addr);
 		host->devtype_data->send_read_id(host);
-		host->buf_start = column;
+		host->buf_start = 0;
 		break;
 
 	case NAND_CMD_ERASE1:
 	case NAND_CMD_ERASE2:
 		host->devtype_data->send_cmd(host, command, false);
+		WARN_ONCE(column != -1,
+			  "Unexpected column value (cmd=%u, col=%d)\n",
+			  command, column);
 		mxc_do_addr_cycle(mtd, column, page_addr);
 
 		break;