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openwrt-xburst/target/linux/ar71xx/patches-3.2/201-spi-ath79-add-delay-between-SCK-changes.patch
juhosg e0b80e41eb ar71xx: add initial support for 3.2
Tested on the following boards:
  ALFA AP96
  TL-MR3220 v1
  TL-WR1043ND v1
  TL-WR2543ND v1
  TL-WR703N v1
  TL-WR741ND v1
  TL-WR741ND v4
  WNDR3700 v1
  WZR-HP-G300NH

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@29868 3c298f89-4303-0410-b956-a3cf2f4a3e73
2012-01-22 22:38:19 +00:00

43 lines
1.3 KiB
Diff

From 48b7e765e6e097d20d809fadd17a4355d26ad6d5 Mon Sep 17 00:00:00 2001
From: Gabor Juhos <juhosg@openwrt.org>
Date: Wed, 11 Jan 2012 20:06:35 +0100
Subject: [PATCH 1/7] spi/ath79: add delay between SCK changes
The driver uses the "as fast as it can" approach
to drive the SCK signal. However this does not
work with certain low speed SPI chips (e.g. the
PCF2123 RTC chip). Add per-bit slowdowns in order
to be able to use the driver with such chips as
well.
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
---
drivers/spi/spi-ath79.c | 8 ++++++++
1 files changed, 8 insertions(+), 0 deletions(-)
--- a/drivers/spi/spi-ath79.c
+++ b/drivers/spi/spi-ath79.c
@@ -52,6 +52,12 @@ static inline struct ath79_spi *ath79_sp
return spi_master_get_devdata(spi->master);
}
+static inline void ath79_spi_delay(unsigned nsecs)
+{
+ if (nsecs)
+ ndelay(nsecs);
+}
+
static void ath79_spi_chipselect(struct spi_device *spi, int is_active)
{
struct ath79_spi *sp = ath79_spidev_to_sp(spi);
@@ -184,7 +190,9 @@ static u32 ath79_spi_txrx_mode0(struct s
/* setup MSB (to slave) on trailing edge */
ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, out);
+ ath79_spi_delay(nsecs);
ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, out | AR71XX_SPI_IOC_CLK);
+ ath79_spi_delay(nsecs);
word <<= 1;
}