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

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

Documentation/devicetree/bindings/i2c/i2c-rcar.txt

+4 −0
Original line number Diff line number Diff line
@@ -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 {

drivers/i2c/busses/i2c-rcar.c

+12 −9
Original line number Diff line number Diff line
@@ -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;



	/*