Commit 0173f525 authored by Pierre-Louis Bossart's avatar Pierre-Louis Bossart Committed by Vinod Koul
Browse files

soundwire: sysfs: add slave status and device number before probe 



The MIPI DisCo device properties that are read by the driver from
platform firmware, or hard-coded in the driver, should only be
provided as sysfs entries when a driver probes successfully.

However the device status and device number is updated even when there
is no driver present, and hence can be updated when a Slave device is
detected on the bus without being described in platform firmware and
without any driver registered/probed.

As suggested by GregKH, the attribute group for Slave status and
device number is is added by default upon device registration.

Credits to Vinod Koul for the status_show() function, shared in a
separate patch and used as is here. The status table was modified to
remove an unnecessary enum and status_show() is handled in a different
group attribute than what was suggested by Vinod.

Tested-by: default avatarSrinivas Kandgatla <srinivas.kandagatla@linaro.org>
Signed-off-by: default avatarPierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Co-developed-by: default avatarVinod Koul <vkoul@kernel.org>
Reviewed-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20200924194430.121058-3-pierre-louis.bossart@linux.intel.com


Signed-off-by: default avatarVinod Koul <vkoul@kernel.org>
parent fcb9d730

Documentation/ABI/testing/sysfs-bus-soundwire-slave

+18 −0
Original line number Diff line number Diff line 
What:		/sys/bus/soundwire/devices/sdw:.../status

		/sys/bus/soundwire/devices/sdw:.../device_number



Date:		September 2020



Contact:	Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>

		Bard Liao <yung-chuan.liao@linux.intel.com>

		Vinod Koul <vkoul@kernel.org>



Description:	SoundWire Slave status



		These properties report the Slave status, e.g. if it

		is UNATTACHED or not, and in the latter case show the

		device_number. This status information is useful to

		detect devices exposed by platform firmware but not

		physically present on the bus, and conversely devices

		not exposed in platform firmware but enumerated.



What:		/sys/bus/soundwire/devices/sdw:.../dev-properties/mipi_revision

		/sys/bus/soundwire/devices/sdw:.../dev-properties/wake_capable

		/sys/bus/soundwire/devices/sdw:.../dev-properties/test_mode_capable

drivers/soundwire/slave.c

+2 −0
Original line number Diff line number Diff line
@@ -6,6 +6,7 @@ 
#include <linux/soundwire/sdw.h>

#include <linux/soundwire/sdw_type.h>

#include "bus.h"

#include "sysfs_local.h"



static void sdw_slave_release(struct device *dev)

{
@@ -51,6 +52,7 @@ int sdw_slave_add(struct sdw_bus *bus, 
	slave->dev.bus = &sdw_bus_type;

	slave->dev.of_node = of_node_get(to_of_node(fwnode));

	slave->dev.type = &sdw_slave_type;

	slave->dev.groups = sdw_slave_status_attr_groups;

	slave->bus = bus;

	slave->status = SDW_SLAVE_UNATTACHED;

	init_completion(&slave->enumeration_complete);

drivers/soundwire/sysfs_local.h

+4 −0
Original line number Diff line number Diff line
@@ -8,6 +8,10 @@ 
 * SDW sysfs APIs -

 */



/* basic attributes to report status of Slave (attachment, dev_num) */

extern const struct attribute_group *sdw_slave_status_attr_groups[];



/* additional device-managed properties reported after driver probe */

int sdw_slave_sysfs_init(struct sdw_slave *slave);

int sdw_slave_sysfs_dpn_init(struct sdw_slave *slave);

drivers/soundwire/sysfs_slave.c

+57 −1
Original line number Diff line number Diff line
@@ -16,9 +16,13 @@ 


/*

 * The sysfs for Slave reflects the MIPI description as given

 * in the MIPI DisCo spec

 * in the MIPI DisCo spec.

 * status and device_number come directly from the MIPI SoundWire

 * 1.x specification.

 *

 * Base file is device

 *	|---- status

 *	|---- device_number

 *	|---- modalias

 *	|---- dev-properties

 *		|---- mipi_revision
@@ -212,3 +216,55 @@ int sdw_slave_sysfs_init(struct sdw_slave *slave) 


	return 0;

}



/*

 * the status is shown in capital letters for UNATTACHED and RESERVED

 * on purpose, to highligh users to the fact that these status values

 * are not expected.

 */

static const char *const slave_status[] = {

	[SDW_SLAVE_UNATTACHED] =  "UNATTACHED",

	[SDW_SLAVE_ATTACHED] = "Attached",

	[SDW_SLAVE_ALERT] = "Alert",

	[SDW_SLAVE_RESERVED] = "RESERVED",

};



static ssize_t status_show(struct device *dev,

			   struct device_attribute *attr, char *buf)

{

	struct sdw_slave *slave = dev_to_sdw_dev(dev);



	return sprintf(buf, "%s\n", slave_status[slave->status]);

}

static DEVICE_ATTR_RO(status);



static ssize_t device_number_show(struct device *dev,

				  struct device_attribute *attr, char *buf)

{

	struct sdw_slave *slave = dev_to_sdw_dev(dev);



	if (slave->status == SDW_SLAVE_UNATTACHED)

		return sprintf(buf, "%s", "N/A");

	else

		return sprintf(buf, "%d", slave->dev_num);

}

static DEVICE_ATTR_RO(device_number);



static struct attribute *slave_status_attrs[] = {

	&dev_attr_status.attr,

	&dev_attr_device_number.attr,

	NULL,

};



/*

 * we don't use ATTRIBUTES_GROUP here since the group is used in a

 * separate file and can't be handled as a static.

 */

static const struct attribute_group sdw_slave_status_attr_group = {

	.attrs	= slave_status_attrs,

};



const struct attribute_group *sdw_slave_status_attr_groups[] = {

	&sdw_slave_status_attr_group,

	NULL

};