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authorDavid Brownell <david-b@pacbell.net>2008-07-03 23:40:16 -0700
committerDavid Woodhouse <David.Woodhouse@intel.com>2008-07-11 14:51:21 +0100
commit23a346ca4a5a6f50f81062456af955155f68e313 (patch)
treed2e37dfb9bdc350aab668ee0cac9168a43cc78ea /drivers/mtd
parent175428b2b3eeacf90dcc171d5915d6b4dc86e917 (diff)
downloadop-kernel-dev-23a346ca4a5a6f50f81062456af955155f68e313.zip
op-kernel-dev-23a346ca4a5a6f50f81062456af955155f68e313.tar.gz
[MTD] [NAND] atmel_nand speedup via {read,write}s{b,w}()
This uses __raw_{read,write}s{b,w}() primitives to access data on NAND chips for more efficient I/O. On an arm926 with memory clocked at 100 MHz, this reduced the elapsed time for a 64 MiB read by 16%. ("dd" /dev/mtd0 to /dev/null, with an 8-bit NAND using hardware ECC and 128KiB blocksize.) Also some minor section tweaks: - Use platform_driver_probe() so no pointer to probe() lingers after that code has been removed at run-time. - Use __exit and __exit_p so the remove() code will normally be removed by the linker. Since these buffer read/write calls are new, this increases the runtime code footprint (by 88 bytes on my build, after the section tweaks). [haavard.skinnemoen@atmel.com: rebase onto atmel_nand rename] Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Signed-off-by: HÃ¥vard Skinnemoen <haavard.skinnemoen@atmel.com> Acked-by: Andrew Victor <linux@maxim.org.za> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
Diffstat (limited to 'drivers/mtd')
-rw-r--r--drivers/mtd/nand/atmel_nand.c46
1 files changed, 41 insertions, 5 deletions
diff --git a/drivers/mtd/nand/atmel_nand.c b/drivers/mtd/nand/atmel_nand.c
index 50700ab..4814fc9 100644
--- a/drivers/mtd/nand/atmel_nand.c
+++ b/drivers/mtd/nand/atmel_nand.c
@@ -142,6 +142,37 @@ static int atmel_nand_device_ready(struct mtd_info *mtd)
}
/*
+ * Minimal-overhead PIO for data access.
+ */
+static void atmel_read_buf(struct mtd_info *mtd, u8 *buf, int len)
+{
+ struct nand_chip *nand_chip = mtd->priv;
+
+ __raw_readsb(nand_chip->IO_ADDR_R, buf, len);
+}
+
+static void atmel_read_buf16(struct mtd_info *mtd, u8 *buf, int len)
+{
+ struct nand_chip *nand_chip = mtd->priv;
+
+ __raw_readsw(nand_chip->IO_ADDR_R, buf, len / 2);
+}
+
+static void atmel_write_buf(struct mtd_info *mtd, const u8 *buf, int len)
+{
+ struct nand_chip *nand_chip = mtd->priv;
+
+ __raw_writesb(nand_chip->IO_ADDR_W, buf, len);
+}
+
+static void atmel_write_buf16(struct mtd_info *mtd, const u8 *buf, int len)
+{
+ struct nand_chip *nand_chip = mtd->priv;
+
+ __raw_writesw(nand_chip->IO_ADDR_W, buf, len / 2);
+}
+
+/*
* write oob for small pages
*/
static int atmel_nand_write_oob_512(struct mtd_info *mtd,
@@ -436,8 +467,14 @@ static int __init atmel_nand_probe(struct platform_device *pdev)
nand_chip->chip_delay = 20; /* 20us command delay time */
- if (host->board->bus_width_16) /* 16-bit bus width */
+ if (host->board->bus_width_16) { /* 16-bit bus width */
nand_chip->options |= NAND_BUSWIDTH_16;
+ nand_chip->read_buf = atmel_read_buf16;
+ nand_chip->write_buf = atmel_write_buf16;
+ } else {
+ nand_chip->read_buf = atmel_read_buf;
+ nand_chip->write_buf = atmel_write_buf;
+ }
platform_set_drvdata(pdev, host);
atmel_nand_enable(host);
@@ -546,7 +583,7 @@ err_nand_ioremap:
/*
* Remove a NAND device.
*/
-static int __devexit atmel_nand_remove(struct platform_device *pdev)
+static int __exit atmel_nand_remove(struct platform_device *pdev)
{
struct atmel_nand_host *host = platform_get_drvdata(pdev);
struct mtd_info *mtd = &host->mtd;
@@ -564,8 +601,7 @@ static int __devexit atmel_nand_remove(struct platform_device *pdev)
}
static struct platform_driver atmel_nand_driver = {
- .probe = atmel_nand_probe,
- .remove = atmel_nand_remove,
+ .remove = __exit_p(atmel_nand_remove),
.driver = {
.name = "atmel_nand",
.owner = THIS_MODULE,
@@ -574,7 +610,7 @@ static struct platform_driver atmel_nand_driver = {
static int __init atmel_nand_init(void)
{
- return platform_driver_register(&atmel_nand_driver);
+ return platform_driver_probe(&atmel_nand_driver, atmel_nand_probe);
}
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