From 48b7e765e6e097d20d809fadd17a4355d26ad6d5 Mon Sep 17 00:00:00 2001 From: Gabor Juhos 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 --- 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; }