ar71xx: improve SPI flash read/write performance

mtd_speedtest results:

                        page write speed
                    old         new       delta
DB120            209 KiB/s   226 KiB/s     +8.13%
TL-WR1043ND v1   122 KiB/s   148 KiB/s    +21.31%
TL-WR703N v1     153 KiB/s   194 KiB/s    +26.80%
TL-MR3220 v1     130 KiB/s   156 KiB/s    +20.00%
TL-WR2543ND v1   158 KiB/s   202 KiB/s    +27.85%
TL-WR741ND v2    122 KiB/s   152 KiB/s    +24.59%
ALFA AP96        229 KiB/s   260 KiB/s    +13.54%
WNDR3700         202 KiB/s   223 KiB/s    +10.40%

                         page read speed
                    old        new       delta
DB120            691 KiB/s   929 KiB/s    +34.44%
TL-WR1043ND v1   372 KiB/s   754 KiB/s   +102.69%
TL-WR703N v1     375 KiB/s   745 KiB/s    +98.67%
TL-MR3220 v1     372 KiB/s   752 KiB/s   +102.15%
TL-WR2543ND v1   307 KiB/s   564 KiB/s    +83.71%
TL-WR741ND v2    315 KiB/s   525 KiB/s    +66.67%
ALFA AP96        515 KiB/s   702 KiB/s    +36.31%
WNDR3700         515 KiB/s   697 KiB/s    +35.34%

SVN-Revision: 31117

1 files changed, 108 insertions, 0 deletions

diff --git a/target/linux/ar71xx/patches-3.2/205-spi-ath79-avoid-multiple-initialization-of-the-SPI-c.patch b/target/linux/ar71xx/patches-3.2/205-spi-ath79-avoid-multiple-initialization-of-the-SPI-c.patch
new file mode 100644
index 0000000000..6230e5d97b
--- /dev/null
+++ b/target/linux/ar71xx/patches-3.2/205-spi-ath79-avoid-multiple-initialization-of-the-SPI-c.patch
@@ -0,0 +1,108 @@
+From 25e681989198e94656eab9df22b8b761abd2ae26 Mon Sep 17 00:00:00 2001
+From: Gabor Juhos <juhosg@openwrt.org>
+Date: Mon, 9 Jan 2012 15:00:46 +0100
+Subject: [PATCH 5/7] spi/ath79: avoid multiple initialization of the SPI controller
+
+Currently we are initializing the SPI controller in
+the chip select line function, and that function is
+called once for each SPI device on the bus. If a
+board has multiple SPI devices, the controller will
+be initialized multiple times.
+
+Introduce ath79_spi_{en,dis}able helper functions,
+and call those from probe/response in order to avoid
+the mutliple initialization of the controller.
+
+Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
+---
+ drivers/spi/spi-ath79.c |   41 ++++++++++++++++++++++++-----------------
+ 1 files changed, 24 insertions(+), 17 deletions(-)
+
+--- a/drivers/spi/spi-ath79.c
++++ b/drivers/spi/spi-ath79.c
+@@ -96,16 +96,8 @@ static void ath79_spi_chipselect(struct
+ 
+ }
+ 
+-static int ath79_spi_setup_cs(struct spi_device *spi)
++static void ath79_spi_enable(struct ath79_spi *sp)
+ {
+-	struct ath79_spi *sp = ath79_spidev_to_sp(spi);
+-	struct ath79_spi_controller_data *cdata;
+-	int status;
+-
+-	cdata = spi->controller_data;
+-	if (spi->chip_select && !cdata)
+-		return -EINVAL;
+-
+ 	/* enable GPIO mode */
+ 	ath79_spi_wr(sp, AR71XX_SPI_REG_FS, AR71XX_SPI_FS_GPIO);
+ 
+@@ -115,6 +107,24 @@ static int ath79_spi_setup_cs(struct spi
+ 
+ 	/* TODO: setup speed? */
+ 	ath79_spi_wr(sp, AR71XX_SPI_REG_CTRL, 0x43);
++}
++
++static void ath79_spi_disable(struct ath79_spi *sp)
++{
++	/* restore CTRL register */
++	ath79_spi_wr(sp, AR71XX_SPI_REG_CTRL, sp->reg_ctrl);
++	/* disable GPIO mode */
++	ath79_spi_wr(sp, AR71XX_SPI_REG_FS, 0);
++}
++
++static int ath79_spi_setup_cs(struct spi_device *spi)
++{
++	struct ath79_spi_controller_data *cdata;
++	int status;
++
++	cdata = spi->controller_data;
++	if (spi->chip_select && !cdata)
++		return -EINVAL;
+ 
+ 	status = 0;
+ 	if (spi->chip_select) {
+@@ -135,17 +145,10 @@ static int ath79_spi_setup_cs(struct spi
+ 
+ static void ath79_spi_cleanup_cs(struct spi_device *spi)
+ {
+-	struct ath79_spi *sp = ath79_spidev_to_sp(spi);
+-
+ 	if (spi->chip_select) {
+ 		struct ath79_spi_controller_data *cdata = spi->controller_data;
+ 		gpio_free(cdata->gpio);
+ 	}
+-
+-	/* restore CTRL register */
+-	ath79_spi_wr(sp, AR71XX_SPI_REG_CTRL, sp->reg_ctrl);
+-	/* disable GPIO mode */
+-	ath79_spi_wr(sp, AR71XX_SPI_REG_FS, 0);
+ }
+ 
+ static int ath79_spi_setup(struct spi_device *spi)
+@@ -271,12 +274,15 @@ static __devinit int ath79_spi_probe(str
+ 	dev_dbg(&pdev->dev, "register read/write delay is %u nsecs\n",
+ 		sp->rrw_delay);
+ 
++	ath79_spi_enable(sp);
+ 	ret = spi_bitbang_start(&sp->bitbang);
+ 	if (ret)
+-		goto err_clk_disable;
++		goto err_disable;
+ 
+ 	return 0;
+ 
++err_disable:
++	ath79_spi_disable(sp);
+ err_clk_disable:
+ 	clk_disable(sp->clk);
+ err_clk_put:
+@@ -295,6 +301,7 @@ static __devexit int ath79_spi_remove(st
+ 	struct ath79_spi *sp = platform_get_drvdata(pdev);
+ 
+ 	spi_bitbang_stop(&sp->bitbang);
++	ath79_spi_disable(sp);
+ 	clk_disable(sp->clk);
+ 	clk_put(sp->clk);
+ 	iounmap(sp->base);