diff options
| author | Masahiro Yamada <yamada.masahiro@socionext.com> | 2018-12-06 12:55:28 +0900 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-12-21 14:15:24 +0100 |
| commit | cab9d27671db270b9fb8f4ed5d3a52cbc94c6438 (patch) | |
| tree | 921c5d73865bda80f27fda2ec3d2ed24bf742ff9 | |
| parent | eb296b2d315bcfaabe9dcd7c43b6795f1fd0f07a (diff) | |
i2c: uniphier-f: fix violation of tLOW requirement for Fast-mode
[ Upstream commit ece27a337d42a3197935711997f2880f0957ed7e ]
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@socionext.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | drivers/i2c/busses/i2c-uniphier-f.c | 19 |
1 files changed, 18 insertions, 1 deletions
diff --git a/drivers/i2c/busses/i2c-uniphier-f.c b/drivers/i2c/busses/i2c-uniphier-f.c index a403e8579b65..bc26ec822e26 100644 --- a/drivers/i2c/busses/i2c-uniphier-f.c +++ b/drivers/i2c/busses/i2c-uniphier-f.c @@ -470,9 +470,26 @@ 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); |