[PATCH 3/4] soundwire: add sdw_show_ping_status() helper

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

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

This helper provides an optional delay parameter to wait for devices
to resync in case of errors, and checks that devices are indeed
attached on the bus.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Rander Wang <rander.wang@intel.com>
Signed-off-by: Bard Liao <yung-chuan.liao@linux.intel.com>
---
 drivers/soundwire/bus.c       | 32 ++++++++++++++++++++++++++++++++
 include/linux/soundwire/sdw.h |  2 ++
 2 files changed, 34 insertions(+)

diff --git a/drivers/soundwire/bus.c b/drivers/soundwire/bus.c
index 2772973eebb1..0a99ac791c7e 100644
--- a/drivers/soundwire/bus.c
+++ b/drivers/soundwire/bus.c
@@ -300,6 +300,38 @@ int sdw_transfer(struct sdw_bus *bus, struct sdw_msg *msg)
 	return ret;
 }
 
+/**
+ * sdw_show_ping_status() - Direct report of PING status, to be used by Peripheral drivers
+ * @bus: SDW bus
+ * @sync_delay: Delay before reading status
+ */
+void sdw_show_ping_status(struct sdw_bus *bus, bool sync_delay)
+{
+	u32 status;
+
+	if (!bus->ops->read_ping_status)
+		return;
+
+	/*
+	 * wait for peripheral to sync if desired. 10-15ms should be more than
+	 * enough in most cases.
+	 */
+	if (sync_delay)
+		usleep_range(10000, 15000);
+
+	mutex_lock(&bus->msg_lock);
+
+	status = bus->ops->read_ping_status(bus);
+
+	mutex_unlock(&bus->msg_lock);
+
+	if (!status)
+		dev_warn(bus->dev, "%s: no peripherals attached\n", __func__);
+	else
+		dev_dbg(bus->dev, "PING status: %#x\n", status);
+}
+EXPORT_SYMBOL(sdw_show_ping_status);
+
 /**
  * sdw_transfer_defer() - Asynchronously transfer message to a SDW Slave device
  * @bus: SDW bus
diff --git a/include/linux/soundwire/sdw.h b/include/linux/soundwire/sdw.h
index a85cf829bb77..9e4537f409c2 100644
--- a/include/linux/soundwire/sdw.h
+++ b/include/linux/soundwire/sdw.h
@@ -926,6 +926,8 @@ int sdw_bus_master_add(struct sdw_bus *bus, struct device *parent,
 		       struct fwnode_handle *fwnode);
 void sdw_bus_master_delete(struct sdw_bus *bus);
 
+void sdw_show_ping_status(struct sdw_bus *bus, bool sync_delay);
+
 /**
  * sdw_port_config: Master or Slave Port configuration
  *
-- 
2.25.1