From afaa9f65c24d815ed4f6133c800884921e051913 Mon Sep 17 00:00:00 2001 From: Anatolij Gustschin Date: Wed, 19 Jan 2011 22:46:32 +0000 Subject: [PATCH] SPI: mxc_spi: add SPI clock calculation and setup to the driver The MXC SPI driver didn't calculate the SPI clock up to now and just used highest possible divider 512 for DATA RATE in the control register. This results in very low transfer rates. The patch adds code to calculate and setup the SPI clock frequency for transfers. Signed-off-by: Anatolij Gustschin Signed-off-by: Stefano Babic --- drivers/spi/mxc_spi.c | 23 ++++++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-) diff --git a/drivers/spi/mxc_spi.c b/drivers/spi/mxc_spi.c index dadf228844..2a4ddade32 100644 --- a/drivers/spi/mxc_spi.c +++ b/drivers/spi/mxc_spi.c @@ -199,15 +199,36 @@ void spi_cs_deactivate(struct spi_slave *slave) !(mxcs->ss_pol)); } +u32 get_cspi_div(u32 div) +{ + int i; + + for (i = 0; i < 8; i++) { + if (div <= (4 << i)) + return i; + } + return i; +} + #if defined(CONFIG_MX31) || defined(CONFIG_MX35) static s32 spi_cfg_mxc(struct mxc_spi_slave *mxcs, unsigned int cs, unsigned int max_hz, unsigned int mode) { unsigned int ctrl_reg; + u32 clk_src; + u32 div; + + clk_src = mxc_get_clock(MXC_CSPI_CLK); + + div = clk_src / max_hz; + div = get_cspi_div(div); + + debug("clk %d Hz, div %d, real clk %d Hz\n", + max_hz, div, clk_src / (4 << div)); ctrl_reg = MXC_CSPICTRL_CHIPSELECT(cs) | MXC_CSPICTRL_BITCOUNT(MXC_CSPICTRL_MAXBITS) | - MXC_CSPICTRL_DATARATE(7) | /* FIXME: calculate data rate */ + MXC_CSPICTRL_DATARATE(div) | MXC_CSPICTRL_EN | #ifdef CONFIG_MX35 MXC_CSPICTRL_SSCTL | -- 2.25.1