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[MTD] [NAND] atmel_nand speedup via {read,write}s{b,w}()

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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: Håvard 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>
This commit is contained in:
David Brownell 2008-07-03 23:40:16 -07:00 committed by David Woodhouse
parent 175428b2b3
commit 23a346ca4a
1 changed files with 41 additions and 5 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

46
drivers/mtd/nand/atmel_nand.c
View file

@ -141,6 +141,37 @@ static int atmel_nand_device_ready(struct mtd_info *mtd)
return gpio_get_value(host->board->rdy_pin);
}
/*
* 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
*/
@ -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);
}