Commit b58f47eb authored by Adrian Ng Ho Yin's avatar Adrian Ng Ho Yin Committed by Alexandre Belloni
Browse files

i3c: add sysfs entry and attribute for Device NACK Retry count 



Document sysfs attribute dev_nack_retry_cnt that controls the number of
automatic retries performed by the I3C controller when a target device
returns a NACK

Add a `dev_nack_retry_count` sysfs attribute to allow reading and updating
the device NACK retry count. A new `dev_nack_retry_count` field and an
optional `set_dev_nack_retry()` callback are added to
i3c_master_controller. The attribute is created only when the callback is
implemented.

Updates are applied under the I3C bus maintenance lock to ensure safe
hardware reconfiguration.

Signed-off-by: default avatarAdrian Ng Ho Yin <adrianhoyin.ng@altera.com>
Reviewed-by: default avatarFrank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/3c4b5082bde64024fc383c44bebeef89ad3c7ed3.1765529948.git.adrianhoyin.ng@altera.com


Signed-off-by: default avatarAlexandre Belloni <alexandre.belloni@bootlin.com>
parent 8f0b4cce

Documentation/ABI/testing/sysfs-bus-i3c

+11 −0
Original line number Diff line number Diff line
@@ -161,3 +161,14 @@ Contact: linux-i3c@vger.kernel.org 
Description:

		These directories are just symbolic links to

		/sys/bus/i3c/devices/i3c-<bus-id>/<bus-id>-<device-pid>.



What:		/sys/bus/i3c/devices/i3c-<bus-id>/<bus-id>-<device-pid>/dev_nack_retry_count

KernelVersion:  6.18

Contact:	linux-i3c@vger.kernel.org

Description:

		Expose the dev_nak_retry_count which controls the number of

		automatic retries that will be performed by the controller when

		the target device returns a NACK response. A value of 0 disables

		the automatic retries. Exist only when I3C constroller supports

		this retry on nack feature.

drivers/i3c/master.c

+39 −0
Original line number Diff line number Diff line
@@ -683,6 +683,39 @@ static ssize_t hotjoin_show(struct device *dev, struct device_attribute *da, cha 


static DEVICE_ATTR_RW(hotjoin);



static ssize_t dev_nack_retry_count_show(struct device *dev,

					 struct device_attribute *attr, char *buf)

{

	return sysfs_emit(buf, "%u\n", dev_to_i3cmaster(dev)->dev_nack_retry_count);

}



static ssize_t dev_nack_retry_count_store(struct device *dev,

					  struct device_attribute *attr,

					  const char *buf, size_t count)

{

	struct i3c_bus *i3cbus = dev_to_i3cbus(dev);

	struct i3c_master_controller *master = dev_to_i3cmaster(dev);

	unsigned long val;

	int ret;



	ret = kstrtoul(buf, 0, &val);

	if (ret)

		return ret;



	i3c_bus_maintenance_lock(i3cbus);

	ret = master->ops->set_dev_nack_retry(master, val);

	i3c_bus_maintenance_unlock(i3cbus);



	if (ret)

		return ret;



	master->dev_nack_retry_count = val;



	return count;

}



static DEVICE_ATTR_RW(dev_nack_retry_count);



static struct attribute *i3c_masterdev_attrs[] = {

	&dev_attr_mode.attr,

	&dev_attr_current_master.attr,
@@ -2959,6 +2992,9 @@ int i3c_master_register(struct i3c_master_controller *master, 
	i3c_master_register_new_i3c_devs(master);

	i3c_bus_normaluse_unlock(&master->bus);



	if (master->ops->set_dev_nack_retry)

		device_create_file(&master->dev, &dev_attr_dev_nack_retry_count);



	return 0;



err_del_dev:
@@ -2984,6 +3020,9 @@ void i3c_master_unregister(struct i3c_master_controller *master) 
{

	i3c_bus_notify(&master->bus, I3C_NOTIFY_BUS_REMOVE);



	if (master->ops->set_dev_nack_retry)

		device_remove_file(&master->dev, &dev_attr_dev_nack_retry_count);



	i3c_master_i2c_adapter_cleanup(master);

	i3c_master_unregister_i3c_devs(master);

	i3c_master_bus_cleanup(master);

include/linux/i3c/master.h

+6 −0
Original line number Diff line number Diff line
@@ -462,6 +462,8 @@ struct i3c_bus { 
 * @enable_hotjoin: enable hot join event detect.

 * @disable_hotjoin: disable hot join event detect.

 * @set_speed: adjust I3C open drain mode timing.

 * @set_dev_nack_retry: configure device NACK retry count for the master

 *                      controller.

 */

struct i3c_master_controller_ops {

	int (*bus_init)(struct i3c_master_controller *master);
@@ -491,6 +493,8 @@ struct i3c_master_controller_ops { 
	int (*enable_hotjoin)(struct i3c_master_controller *master);

	int (*disable_hotjoin)(struct i3c_master_controller *master);

	int (*set_speed)(struct i3c_master_controller *master, enum i3c_open_drain_speed speed);

	int (*set_dev_nack_retry)(struct i3c_master_controller *master,

				  unsigned long dev_nack_retry_cnt);

};



/**
@@ -514,6 +518,7 @@ struct i3c_master_controller_ops { 
 *	in a thread context. Typical examples are Hot Join processing which

 *	requires taking the bus lock in maintenance, which in turn, can only

 *	be done from a sleep-able context

 * @dev_nack_retry_count: retry count when slave device nack

 *

 * A &struct i3c_master_controller has to be registered to the I3C subsystem

 * through i3c_master_register(). None of &struct i3c_master_controller fields
@@ -534,6 +539,7 @@ struct i3c_master_controller { 
	} boardinfo;

	struct i3c_bus bus;

	struct workqueue_struct *wq;

	unsigned int dev_nack_retry_count;

};



/**