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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;
}
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