[PATCH v3 09/22] soundwire: bus: add helper to reset Slave status to UNATTACHED

[Pierre-Louis Bossart]

When resuming, we need to re-enumerate and restart from UNATTACHED.

This will help implement a more robust state machine avoiding race
conditions on resume.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>
---
 drivers/soundwire/bus.c | 24 ++++++++++++++++++++++++
 drivers/soundwire/bus.h |  2 ++
 2 files changed, 26 insertions(+)

diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
index d0461bb2fb86..b050a45d1745 100644
--- a/drivers/soundwire/bus.c
+++ b/drivers/soundwire/bus.c
@@ -1108,3 +1108,27 @@ int sdw_handle_slave_status(struct sdw_bus *bus,
 	return ret;
 }
 EXPORT_SYMBOL(sdw_handle_slave_status);
+
+void sdw_clear_slave_status(struct sdw_bus *bus)
+{
+	struct sdw_slave *slave;
+	int i;
+
+	/* Check all non-zero devices */
+	for (i = 1; i <= SDW_MAX_DEVICES; i++) {
+		mutex_lock(&bus->bus_lock);
+		if (test_bit(i, bus->assigned) == false) {
+			mutex_unlock(&bus->bus_lock);
+			continue;
+		}
+		mutex_unlock(&bus->bus_lock);
+
+		slave = sdw_get_slave(bus, i);
+		if (!slave)
+			continue;
+
+		if (slave->status != SDW_SLAVE_UNATTACHED)
+			sdw_modify_slave_status(slave, SDW_SLAVE_UNATTACHED);
+	}
+}
+EXPORT_SYMBOL(sdw_clear_slave_status);
diff --git a/drivers/soundwire/bus.h b/drivers/soundwire/bus.h
index 93e7bbab0938..4e6fb5d2f5cc 100644
--- a/drivers/soundwire/bus.h
+++ b/drivers/soundwire/bus.h
@@ -167,4 +167,6 @@ sdw_update(struct sdw_slave *slave, u32 addr, u8 mask, u8 val)
 	return sdw_write(slave, addr, tmp);
 }
 
+void sdw_clear_slave_status(struct sdw_bus *bus);
+
 #endif /* __SDW_BUS_H */
-- 
2.20.1