mei: bus: add more client attributes to sysfs

Export more client attributes via sysfs that are usually obtained
upon connection. In some cases, for example a monitoring application
may wish to know the attributes without actually performing the connection.
Added attributes:
max number of connections, fixed address, max message length.
Signed-off-by: Alexander Usyskin <alexander.usyskin@intel.com>
Signed-off-by: Tomas Winkler <tomas.winkler@intel.com>
Link: https://lore.kernel.org/r/20191116142136.17535-1-tomas.winkler@intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/ABI/testing/sysfs-bus-mei

@@ -26,3 +26,24 @@ KernelVersion:	4.3
 Contact:	Tomas Winkler <tomas.winkler@intel.com>
 Description:	Stores mei client protocol version
 		Format: %d
+
+What:		/sys/bus/mei/devices/.../max_conn
+Date:		Nov 2019
+KernelVersion:	5.5
+Contact:	Tomas Winkler <tomas.winkler@intel.com>
+Description:	Stores mei client maximum number of connections
+		Format: %d
+
+What:		/sys/bus/mei/devices/.../fixed
+Date:		Nov 2019
+KernelVersion:	5.5
+Contact:	Tomas Winkler <tomas.winkler@intel.com>
+Description:	Stores mei client fixed address, if any
+		Format: %d
+
+What:		/sys/bus/mei/devices/.../max_len
+Date:		Nov 2019
+KernelVersion:	5.5
+Contact:	Tomas Winkler <tomas.winkler@intel.com>
+Description:	Stores mei client maximum message length
+		Format: %d

drivers/misc/mei/bus.c

@@ -791,11 +791,44 @@ static ssize_t modalias_show(struct device *dev, struct device_attribute *a,
 }
 static DEVICE_ATTR_RO(modalias);
 
+static ssize_t max_conn_show(struct device *dev, struct device_attribute *a,
+			     char *buf)
+{
+	struct mei_cl_device *cldev = to_mei_cl_device(dev);
+	u8 maxconn = mei_me_cl_max_conn(cldev->me_cl);
+
+	return scnprintf(buf, PAGE_SIZE, "%d", maxconn);
+}
+static DEVICE_ATTR_RO(max_conn);
+
+static ssize_t fixed_show(struct device *dev, struct device_attribute *a,
+			  char *buf)
+{
+	struct mei_cl_device *cldev = to_mei_cl_device(dev);
+	u8 fixed = mei_me_cl_fixed(cldev->me_cl);
+
+	return scnprintf(buf, PAGE_SIZE, "%d", fixed);
+}
+static DEVICE_ATTR_RO(fixed);
+
+static ssize_t max_len_show(struct device *dev, struct device_attribute *a,
+			    char *buf)
+{
+	struct mei_cl_device *cldev = to_mei_cl_device(dev);
+	u32 maxlen = mei_me_cl_max_len(cldev->me_cl);
+
+	return scnprintf(buf, PAGE_SIZE, "%u", maxlen);
+}
+static DEVICE_ATTR_RO(max_len);
+
 static struct attribute *mei_cldev_attrs[] = {
 	&dev_attr_name.attr,
 	&dev_attr_uuid.attr,
 	&dev_attr_version.attr,
 	&dev_attr_modalias.attr,
+	&dev_attr_max_conn.attr,
+	&dev_attr_fixed.attr,
+	&dev_attr_max_len.attr,
 	NULL,
 };
 ATTRIBUTE_GROUPS(mei_cldev);

drivers/misc/mei/client.h

@@ -69,6 +69,42 @@ static inline u8 mei_me_cl_ver(const struct mei_me_client *me_cl)
 	return me_cl->props.protocol_version;
 }
 
+/**
+ * mei_me_cl_max_conn - return me client max number of connections
+ *
+ * @me_cl: me client
+ *
+ * Return: me client max number of connections
+ */
+static inline u8 mei_me_cl_max_conn(const struct mei_me_client *me_cl)
+{
+	return me_cl->props.max_number_of_connections;
+}
+
+/**
+ * mei_me_cl_fixed - return me client fixed address, if any
+ *
+ * @me_cl: me client
+ *
+ * Return: me client fixed address
+ */
+static inline u8 mei_me_cl_fixed(const struct mei_me_client *me_cl)
+{
+	return me_cl->props.fixed_address;
+}
+
+/**
+ * mei_me_cl_max_len - return me client max msg length
+ *
+ * @me_cl: me client
+ *
+ * Return: me client max msg length
+ */
+static inline u32 mei_me_cl_max_len(const struct mei_me_client *me_cl)
+{
+	return me_cl->props.max_msg_length;
+}
+
 /*
  * MEI IO Functions
  */