diff options
| author | Wolfram Sang <wsa+renesas@sang-engineering.com> | 2015-12-08 10:37:49 +0100 |
|---|---|---|
| committer | Wolfram Sang <wsa@the-dreams.de> | 2015-12-14 10:51:10 +0100 |
| commit | ca68eade666a6ad7e954cc8c1af07ce477726087 (patch) | |
| tree | 284e32c5c439c6f5a731d6ad89f7ce8bf37d536c | |
| parent | c7881871de878ab3a40b973142e4ca17857b6b73 (diff) | |
i2c: rcar: honor additional i2c timings from DT
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
| -rw-r--r-- | Documentation/devicetree/bindings/i2c/i2c-rcar.txt | 4 | ||||
| -rw-r--r-- | drivers/i2c/busses/i2c-rcar.c | 21 |
2 files changed, 16 insertions, 9 deletions
diff --git a/Documentation/devicetree/bindings/i2c/i2c-rcar.txt b/Documentation/devicetree/bindings/i2c/i2c-rcar.txt index ea406eb20fa5..95e97223a71c 100644 --- a/Documentation/devicetree/bindings/i2c/i2c-rcar.txt +++ b/Documentation/devicetree/bindings/i2c/i2c-rcar.txt @@ -20,6 +20,10 @@ Optional properties: propoerty indicates the default frequency 100 kHz. - clocks: clock specifier. +- i2c-scl-falling-time-ns: see i2c.txt +- i2c-scl-internal-delay-ns: see i2c.txt +- i2c-scl-rising-time-ns: see i2c.txt + Examples : i2c0: i2c@e6508000 { diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c index c663f4389bf8..b2389c492579 100644 --- a/drivers/i2c/busses/i2c-rcar.c +++ b/drivers/i2c/busses/i2c-rcar.c @@ -164,12 +164,15 @@ static int rcar_i2c_bus_barrier(struct rcar_i2c_priv *priv) static int rcar_i2c_clock_calculate(struct rcar_i2c_priv *priv, struct i2c_timings *t) { - u32 scgd, cdf, round, ick, scl, cdf_width; + u32 scgd, cdf, round, ick, sum, scl, cdf_width; unsigned long rate; struct device *dev = rcar_i2c_priv_to_dev(priv); /* Fall back to previously used values if not supplied */ t->bus_freq_hz = t->bus_freq_hz ?: 100000; + t->scl_fall_ns = t->scl_fall_ns ?: 35; + t->scl_rise_ns = t->scl_rise_ns ?: 200; + t->scl_int_delay_ns = t->scl_int_delay_ns ?: 50; switch (priv->devtype) { case I2C_RCAR_GEN1: @@ -193,9 +196,9 @@ static int rcar_i2c_clock_calculate(struct rcar_i2c_priv *priv, struct i2c_timin * SCL = ick / (20 + SCGD * 8 + F[(ticf + tr + intd) * ick]) * * ick : I2C internal clock < 20 MHz - * ticf : I2C SCL falling time = 35 ns here - * tr : I2C SCL rising time = 200 ns here - * intd : LSI internal delay = 50 ns here + * ticf : I2C SCL falling time + * tr : I2C SCL rising time + * intd : LSI internal delay * clkp : peripheral_clk * F[] : integer up-valuation */ @@ -211,12 +214,12 @@ static int rcar_i2c_clock_calculate(struct rcar_i2c_priv *priv, struct i2c_timin * it is impossible to calculate large scale * number on u32. separate it * - * F[(ticf + tr + intd) * ick] - * = F[(35 + 200 + 50)ns * ick] - * = F[285 * ick / 1000000000] - * = F[(ick / 1000000) * 285 / 1000] + * F[(ticf + tr + intd) * ick] with sum = (ticf + tr + intd) + * = F[sum * ick / 1000000000] + * = F[(ick / 1000000) * sum / 1000] */ - round = (ick + 500000) / 1000000 * 285; + sum = t->scl_fall_ns + t->scl_rise_ns + t->scl_int_delay_ns; + round = (ick + 500000) / 1000000 * sum; round = (round + 500) / 1000; /* |