Currently, the clock duty is set as tLOW/tHIGH = 1/1. For Fast-mode, tLOW is set to 1.25 us while the I2C spec requires tLOW >= 1.3 us. tLOW/tHIGH = 5/4 would meet both Standard-mode and Fast-mode: Standard-mode: tLOW = 5.56 us, tHIGH = 4.44 us Fast-mode: tLOW = 1.39 us, tHIGH = 1.11 us Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> --- drivers/i2c/busses/i2c-uniphier-f.c | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-) diff --git a/drivers/i2c/busses/i2c-uniphier-f.c b/drivers/i2c/busses/i2c-uniphier-f.c index d8a5db14..03da4a5 100644 --- a/drivers/i2c/busses/i2c-uniphier-f.c +++ b/drivers/i2c/busses/i2c-uniphier-f.c @@ -518,9 +518,26 @@ static void uniphier_fi2c_hw_init(struct uniphier_fi2c_priv *priv) uniphier_fi2c_reset(priv); + /* + * Standard-mode: tLOW + tHIGH = 10 us + * Fast-mode: tLOW + tHIGH = 2.5 us + */ writel(cyc, priv->membase + UNIPHIER_FI2C_CYC); - writel(cyc / 2, priv->membase + UNIPHIER_FI2C_LCTL); + /* + * Standard-mode: tLOW = 4.7 us, tHIGH = 4.0 us, tBUF = 4.7 us + * Fast-mode: tLOW = 1.3 us, tHIGH = 0.6 us, tBUF = 1.3 us + * "tLow/tHIGH = 5/4" meets both. + */ + writel(cyc * 5 / 9, priv->membase + UNIPHIER_FI2C_LCTL); + /* + * Standard-mode: tHD;STA = 4.0 us, tSU;STA = 4.7 us, tSU;STO = 4.0 us + * Fast-mode: tHD;STA = 0.6 us, tSU;STA = 0.6 us, tSU;STO = 0.6 us + */ writel(cyc / 2, priv->membase + UNIPHIER_FI2C_SSUT); + /* + * Standard-mode: tSU;DAT = 250 ns + * Fast-mode: tSU;DAT = 100 ns + */ writel(cyc / 16, priv->membase + UNIPHIER_FI2C_DSUT); uniphier_fi2c_prepare_operation(priv); -- 2.7.4
