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@xxxxxxxxxx>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>
---
.../ABI/testing/sysfs-bus-soundwire-slave | 18 ++++++
drivers/soundwire/slave.c | 2 +
drivers/soundwire/sysfs_local.h | 4 ++
drivers/soundwire/sysfs_slave.c | 59 ++++++++++++++++++-
4 files changed, 82 insertions(+), 1 deletion(-)
diff --git a/Documentation/ABI/testing/sysfs-bus-soundwire-slave b/Documentation/ABI/testing/sysfs-bus-soundwire-slave
index db4c9511d1aa..425adf7b8aec 100644
--- a/Documentation/ABI/testing/sysfs-bus-soundwire-slave
+++ b/Documentation/ABI/testing/sysfs-bus-soundwire-slave
@@ -1,3 +1,21 @@
+What: /sys/bus/soundwire/devices/sdw:.../dev-status/status
+ /sys/bus/soundwire/devices/sdw:.../dev-status/device_number
+
+Date: September 2020
+
+Contact: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>
+ Bard Liao <yung-chuan.liao@xxxxxxxxxxxxxxx>
+ Vinod Koul <vkoul@xxxxxxxxxx>
+
+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
diff --git a/drivers/soundwire/slave.c b/drivers/soundwire/slave.c
index 19b012310c29..a08f4081c1c4 100644
--- a/drivers/soundwire/slave.c
+++ b/drivers/soundwire/slave.c
@@ -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);
diff --git a/drivers/soundwire/sysfs_local.h b/drivers/soundwire/sysfs_local.h
index ff60adee3c41..7268bc24c538 100644
--- a/drivers/soundwire/sysfs_local.h
+++ b/drivers/soundwire/sysfs_local.h
@@ -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);
diff --git a/drivers/soundwire/sysfs_slave.c b/drivers/soundwire/sysfs_slave.c
index f510071b0add..99c0bdd4a726 100644
--- a/drivers/soundwire/sysfs_slave.c
+++ b/drivers/soundwire/sysfs_slave.c
@@ -16,10 +16,14 @@
/*
* The sysfs for Slave reflects the MIPI description as given
- * in the MIPI DisCo spec
+ * in the MIPI DisCo spec. dev-status properties come directly
+ * from the MIPI SoundWire specification.
*
* Base file is device
* |---- modalias
+ * |---- dev-status
+ * |---- status
+ * |---- device_number
* |---- dev-properties
* |---- mipi_revision
* |---- wake_capable
@@ -212,3 +216,56 @@ 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 we want to add a subdirectory
+ * for device-status
+ */
+static const struct attribute_group sdw_slave_status_attr_group = {
+ .attrs = slave_status_attrs,
+ .name = "dev-status",
+};
+
+const struct attribute_group *sdw_slave_status_attr_groups[] = {
+ &sdw_slave_status_attr_group,
+ NULL
+};
--
2.25.1
