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

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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: Srinivas Kandgatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Co-developed-by: Vinod Koul <vkoul@kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20200924194430.121058-3-pierre-louis.bossart@linux.intel.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
This commit is contained in:
Pierre-Louis Bossart 2020-09-24 14:44:30 -05:00 committed by Vinod Koul
parent fcb9d730be
commit 0173f525b2
4 changed files with 81 additions and 1 deletions
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18
Documentation/ABI/testing/sysfs-bus-soundwire-slave
View File

@ -1,3 +1,21 @@
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

2
drivers/soundwire/slave.c
View File

@ -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);

4
drivers/soundwire/sysfs_local.h
View File

@ -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);

58
drivers/soundwire/sysfs_slave.c
View File

@ -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
};