From 8203b201eaa1b33758956294b3ec70b326f8ba5c Mon Sep 17 00:00:00 2001 From: Valentin Longchamp Date: Wed, 15 Aug 2012 05:31:49 +0000 Subject: kw_spi: fix clock prescaler computation The computation was not correct with low clock values: setting a 1MHz clock would result in an overlap that would then configure a 25Mhz clock. This patch implements a correct computation method according to the kirkwood functionnal spec. table 600 (Serial Memory Interface Configuration Register). Signed-off-by: Valentin Longchamp cc: Holger Brunck cc: Prafulla Wadaskar Acked-by: Prafulla Wadaskar Signed-off-by: Prafulla Wadaskar --- drivers/spi/kirkwood_spi.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'drivers') diff --git a/drivers/spi/kirkwood_spi.c b/drivers/spi/kirkwood_spi.c index f4523a3..a7cda75 100644 --- a/drivers/spi/kirkwood_spi.c +++ b/drivers/spi/kirkwood_spi.c @@ -56,8 +56,9 @@ struct spi_slave *spi_setup_slave(unsigned int bus, unsigned int cs, writel(~KWSPI_CSN_ACT | KWSPI_SMEMRDY, &spireg->ctrl); /* calculate spi clock prescaller using max_hz */ - data = ((CONFIG_SYS_TCLK / 2) / max_hz) & KWSPI_CLKPRESCL_MASK; - data |= 0x10; + data = ((CONFIG_SYS_TCLK / 2) / max_hz) + 0x10; + data = data < KWSPI_CLKPRESCL_MIN ? KWSPI_CLKPRESCL_MIN : data; + data = data > KWSPI_CLKPRESCL_MASK ? KWSPI_CLKPRESCL_MASK : data; /* program spi clock prescaller using max_hz */ writel(KWSPI_ADRLEN_3BYTE | data, &spireg->cfg); -- cgit v1.1