Commit ca68eade authored by Wolfram Sang's avatar Wolfram Sang Committed by Wolfram Sang

i2c: rcar: honor additional i2c timings from DT

Signed-off-by: default avatarWolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: default avatarWolfram Sang <wsa@the-dreams.de>
parent c7881871
...@@ -20,6 +20,10 @@ Optional properties: ...@@ -20,6 +20,10 @@ Optional properties:
propoerty indicates the default frequency 100 kHz. propoerty indicates the default frequency 100 kHz.
- clocks: clock specifier. - 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 : Examples :
i2c0: i2c@e6508000 { i2c0: i2c@e6508000 {
......
...@@ -164,12 +164,15 @@ static int rcar_i2c_bus_barrier(struct rcar_i2c_priv *priv) ...@@ -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) 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; unsigned long rate;
struct device *dev = rcar_i2c_priv_to_dev(priv); struct device *dev = rcar_i2c_priv_to_dev(priv);
/* Fall back to previously used values if not supplied */ /* Fall back to previously used values if not supplied */
t->bus_freq_hz = t->bus_freq_hz ?: 100000; 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) { switch (priv->devtype) {
case I2C_RCAR_GEN1: case I2C_RCAR_GEN1:
...@@ -193,9 +196,9 @@ static int rcar_i2c_clock_calculate(struct rcar_i2c_priv *priv, struct i2c_timin ...@@ -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]) * SCL = ick / (20 + SCGD * 8 + F[(ticf + tr + intd) * ick])
* *
* ick : I2C internal clock < 20 MHz * ick : I2C internal clock < 20 MHz
* ticf : I2C SCL falling time = 35 ns here * ticf : I2C SCL falling time
* tr : I2C SCL rising time = 200 ns here * tr : I2C SCL rising time
* intd : LSI internal delay = 50 ns here * intd : LSI internal delay
* clkp : peripheral_clk * clkp : peripheral_clk
* F[] : integer up-valuation * F[] : integer up-valuation
*/ */
...@@ -211,12 +214,12 @@ static int rcar_i2c_clock_calculate(struct rcar_i2c_priv *priv, struct i2c_timin ...@@ -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 * it is impossible to calculate large scale
* number on u32. separate it * number on u32. separate it
* *
* F[(ticf + tr + intd) * ick] * F[(ticf + tr + intd) * ick] with sum = (ticf + tr + intd)
* = F[(35 + 200 + 50)ns * ick] * = F[sum * ick / 1000000000]
* = F[285 * ick / 1000000000] * = F[(ick / 1000000) * sum / 1000]
* = F[(ick / 1000000) * 285 / 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; round = (round + 500) / 1000;
/* /*
......
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