Commit 7ca5f6be authored by Wolfram Sang's avatar Wolfram Sang Committed by Wolfram Sang
Browse files

i2c: recovery: add get_bus_free callback 



Some IP cores have an internal 'bus free' logic which may be more
advanced than just checking if SDA is high. Add a separate callback to
get this status. Filling it is optional.

Signed-off-by: default avatarWolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: default avatarWolfram Sang <wsa@the-dreams.de>
parent 0b71026c

drivers/i2c/i2c-core-base.c

+23 −4
Original line number Diff line number Diff line
@@ -158,6 +158,22 @@ static void set_sda_gpio_value(struct i2c_adapter *adap, int val) 
	gpiod_set_value_cansleep(adap->bus_recovery_info->sda_gpiod, val);

}



static int i2c_generic_bus_free(struct i2c_adapter *adap)

{

	struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;

	int ret = -EOPNOTSUPP;



	if (bri->get_bus_free)

		ret = bri->get_bus_free(adap);

	else if (bri->get_sda)

		ret = bri->get_sda(adap);



	if (ret < 0)

		return ret;



	return ret ? 0 : -EBUSY;

}



/*

 * We are generating clock pulses. ndelay() determines durating of clk pulses.

 * We will generate clock with rate 100 KHz and so duration of both clock levels
@@ -169,7 +185,7 @@ static void set_sda_gpio_value(struct i2c_adapter *adap, int val) 
int i2c_generic_scl_recovery(struct i2c_adapter *adap)

{

	struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;

	int i = 0, val = 1, ret = 0;

	int i = 0, val = 1, ret;



	if (bri->prepare_recovery)

		bri->prepare_recovery(adap);
@@ -207,14 +223,17 @@ int i2c_generic_scl_recovery(struct i2c_adapter *adap) 
			bri->set_sda(adap, val);

		ndelay(RECOVERY_NDELAY / 2);



		/* Break if SDA is high */

		if (val && bri->get_sda) {

			ret = bri->get_sda(adap) ? 0 : -EBUSY;

		if (val) {

			ret = i2c_generic_bus_free(adap);

			if (ret == 0)

				break;

		}

	}



	/* If we can't check bus status, assume recovery worked */

	if (ret == -EOPNOTSUPP)

		ret = 0;



	if (bri->unprepare_recovery)

		bri->unprepare_recovery(adap);

include/linux/i2c.h

+3 −0
Original line number Diff line number Diff line
@@ -587,6 +587,8 @@ struct i2c_timings { 
 * @set_sda: This sets/clears the SDA line. This or get_sda() is mandatory for

 *	generic SCL recovery. Populated internally, if sda_gpio is a valid GPIO,

 *	for generic GPIO recovery.

 * @get_bus_free: Returns the bus free state as seen from the IP core in case it

 *	has a more complex internal logic than just reading SDA. Optional.

 * @prepare_recovery: This will be called before starting recovery. Platform may

 *	configure padmux here for SDA/SCL line or something else they want.

 * @unprepare_recovery: This will be called after completing recovery. Platform
@@ -601,6 +603,7 @@ struct i2c_bus_recovery_info { 
	void (*set_scl)(struct i2c_adapter *adap, int val);

	int (*get_sda)(struct i2c_adapter *adap);

	void (*set_sda)(struct i2c_adapter *adap, int val);

	int (*get_bus_free)(struct i2c_adapter *adap);



	void (*prepare_recovery)(struct i2c_adapter *adap);

	void (*unprepare_recovery)(struct i2c_adapter *adap);