From: Austin Christ Date: Thu, 10 May 2018 16:13:56 +0000 (-0600) Subject: i2c: qup: Correct duty cycle for FM and FM+ X-Git-Tag: v4.18-rc1~27^2~9 X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=71fbafcc45fed7c647987495900b8f6ff29fc5aa;p=linux.git i2c: qup: Correct duty cycle for FM and FM+ The I2C spec UM10204 Rev. 6 specifies the following timings. Standard Fast Mode Fast Mode Plus SCL low 4.7us 1.3us 0.5us SCL high 4.0us 0.6us 0.26us This results in a 33%/66% duty cycle as opposed to the 50%/50% duty cycle used for Standard-mode. Add High Time Divider settings to correct duty cycle for FM(400kHz) and FM+(1MHz). Signed-off-by: Austin Christ Reviewed-by: Sricharan R Reviewed-by: Andy Gross Signed-off-by: Wolfram Sang --- diff --git a/drivers/i2c/busses/i2c-qup.c b/drivers/i2c/busses/i2c-qup.c index ce5f215cd7e8..f87f29f5be65 100644 --- a/drivers/i2c/busses/i2c-qup.c +++ b/drivers/i2c/busses/i2c-qup.c @@ -1855,9 +1855,15 @@ static int qup_i2c_probe(struct platform_device *pdev) size = QUP_INPUT_FIFO_SIZE(io_mode); qup->in_fifo_sz = qup->in_blk_sz * (2 << size); - fs_div = ((src_clk_freq / clk_freq) / 2) - 3; hs_div = 3; - qup->clk_ctl = (hs_div << 8) | (fs_div & 0xff); + if (clk_freq <= I2C_STANDARD_FREQ) { + fs_div = ((src_clk_freq / clk_freq) / 2) - 3; + qup->clk_ctl = (hs_div << 8) | (fs_div & 0xff); + } else { + /* 33%/66% duty cycle */ + fs_div = ((src_clk_freq / clk_freq) - 6) * 2 / 3; + qup->clk_ctl = ((fs_div / 2) << 16) | (hs_div << 8) | (fs_div & 0xff); + } /* * Time it takes for a byte to be clocked out on the bus.