| Message ID | 1525968837-13381-4-git-send-email-austinwc@codeaurora.org |
|---|---|
| State | Accepted |
| Headers | show |
| Series | Add Fast Mode Plus and other fixes | expand |
On Thu, May 10, 2018 at 10:13:56AM -0600, Austin Christ wrote: > 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 <austinwc@codeaurora.org> > Reviewed-by: Sricharan R <sricharan@codeaurora.org> > --- Looks good to me. Reviewed-by: Andy Gross <andy.gross@linaro.org>
diff --git a/drivers/i2c/busses/i2c-qup.c b/drivers/i2c/busses/i2c-qup.c index ce5f215..f87f29f 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.
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 <austinwc@codeaurora.org> Reviewed-by: Sricharan R <sricharan@codeaurora.org> --- v1: - Initial v2: - No changes v3: - No changes --- drivers/i2c/busses/i2c-qup.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-)