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 Signed-off-by: Vinod Koul vkoul@kernel.org --- .../ABI/testing/sysfs-bus-soundwire-slave | 18 ++++++ drivers/soundwire/slave.c | 2 + drivers/soundwire/sysfs_local.h | 4 ++ drivers/soundwire/sysfs_slave.c | 58 ++++++++++++++++++- 4 files changed, 81 insertions(+), 1 deletion(-)
diff --git a/Documentation/ABI/testing/sysfs-bus-soundwire-slave b/Documentation/ABI/testing/sysfs-bus-soundwire-slave index db4c9511d1aa..d324aa0b678f 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:.../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 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..b48b6617a396 100644 --- a/drivers/soundwire/sysfs_slave.c +++ b/drivers/soundwire/sysfs_slave.c @@ -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 +};