From: David Brownell Date: Fri, 4 Jul 2008 06:40:16 +0000 (-0700) Subject: [MTD] [NAND] atmel_nand speedup via {read,write}s{b,w}() X-Git-Tag: v2.6.27-rc1~69^2~23 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=23a346ca4a5a6f50f81062456af955155f68e313;p=linux-2.6 [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 Signed-off-by: Håvard Skinnemoen Acked-by: Andrew Victor Signed-off-by: Andrew Morton Signed-off-by: David Woodhouse --- diff --git a/drivers/mtd/nand/atmel_nand.c b/drivers/mtd/nand/atmel_nand.c index 50700ab5a5..4814fc9b23 100644 --- a/drivers/mtd/nand/atmel_nand.c +++ b/drivers/mtd/nand/atmel_nand.c @@ -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); }