serial: Convert serial_rs485 to kernel doc

Convert struct serial_rs485 comments to kernel doc format and include
it into documentation.

Suggested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Bagas Sanjaya <bagasdotme@gmail.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20221019093343.9546-2-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/driver-api/serial/serial-rs485.rst

@@ -29,11 +29,11 @@ RS485 Serial Communications
 3. Data Structures Already Available in the Kernel
 ==================================================
 
-   The Linux kernel provides the serial_rs485 structure (see [1]) to handle
-   RS485 communications. This data structure is used to set and configure RS485
+   The Linux kernel provides the serial_rs485 structure to handle RS485
+   communications. This data structure is used to set and configure RS485
    parameters in the platform data and in ioctls.
 
-   The device tree can also provide RS485 boot time parameters (see [2]
+   The device tree can also provide RS485 boot time parameters (see [1]
    for bindings). The driver is in charge of filling this data structure from
    the values given by the device tree.
 
@@ -47,6 +47,9 @@ RS485 Serial Communications
    for the uart_port. TIOCGRS485 ioctl can be used to read back the
    serial_rs485 structure matching to the current configuration.
 
+.. kernel-doc:: include/uapi/linux/serial.h
+   :identifiers: serial_rs485
+
 4. Usage from user-level
 ========================
 
@@ -126,6 +129,4 @@ RS485 Serial Communications
 6. References
 =============
 
- [1]	include/uapi/linux/serial.h
-
- [2]	Documentation/devicetree/bindings/serial/rs485.txt
+ [1]	Documentation/devicetree/bindings/serial/rs485.txt

include/uapi/linux/serial.h

@@ -107,33 +107,50 @@ struct serial_icounter_struct {
 	int reserved[9];
 };
 
-/*
+/**
+ * struct serial_rs485 - serial interface for controlling RS485 settings.
+ * @flags:			RS485 feature flags.
+ * @delay_rts_before_send:	Delay before send (milliseconds).
+ * @delay_rts_after_send:	Delay after send (milliseconds).
+ * @addr_recv:			Receive filter for RS485 addressing mode
+ *				(used only when %SER_RS485_ADDR_RECV is set).
+ * @addr_dest:			Destination address for RS485 addressing mode
+ *				(used only when %SER_RS485_ADDR_DEST is set).
+ * @padding0:			Padding (set to zero).
+ * @padding1:			Padding (set to zero).
+ * @padding:			Deprecated, use @padding0 and @padding1 instead.
+ *				Do not use with @addr_recv and @addr_dest (due to
+ *				overlap).
+ *
  * Serial interface for controlling RS485 settings on chips with suitable
  * support. Set with TIOCSRS485 and get with TIOCGRS485 if supported by your
  * platform. The set function returns the new state, with any unsupported bits
  * reverted appropriately.
+ *
+ * The flag bits are:
+ *
+ * * %SER_RS485_ENABLED		- RS485 enabled.
+ * * %SER_RS485_RTS_ON_SEND	- Logical level for RTS pin when sending.
+ * * %SER_RS485_RTS_AFTER_SEND	- Logical level for RTS pin after sent.
+ * * %SER_RS485_RX_DURING_TX	- Full-duplex RS485 line.
+ * * %SER_RS485_TERMINATE_BUS	- Enable bus termination (if supported).
+ * * %SER_RS485_ADDRB		- Enable RS485 addressing mode.
+ * * %SER_RS485_ADDR_RECV - Receive address filter (enables @addr_recv). Requires %SER_RS485_ADDRB.
+ * * %SER_RS485_ADDR_DEST - Destination address (enables @addr_dest). Requires %SER_RS485_ADDRB.
  */
-
 struct serial_rs485 {
-	__u32	flags;			/* RS485 feature flags */
-#define SER_RS485_ENABLED		(1 << 0)	/* If enabled */
-#define SER_RS485_RTS_ON_SEND		(1 << 1)	/* Logical level for
-							   RTS pin when
-							   sending */
-#define SER_RS485_RTS_AFTER_SEND	(1 << 2)	/* Logical level for
-							   RTS pin after sent*/
+	__u32	flags;
+#define SER_RS485_ENABLED		(1 << 0)
+#define SER_RS485_RTS_ON_SEND		(1 << 1)
+#define SER_RS485_RTS_AFTER_SEND	(1 << 2)
 #define SER_RS485_RX_DURING_TX		(1 << 4)
-#define SER_RS485_TERMINATE_BUS		(1 << 5)	/* Enable bus
-							   termination
-							   (if supported) */
-
-/* RS-485 addressing mode */
-#define SER_RS485_ADDRB			(1 << 6)	/* Enable addressing mode */
-#define SER_RS485_ADDR_RECV		(1 << 7)	/* Receive address filter */
-#define SER_RS485_ADDR_DEST		(1 << 8)	/* Destination address */
+#define SER_RS485_TERMINATE_BUS		(1 << 5)
+#define SER_RS485_ADDRB			(1 << 6)
+#define SER_RS485_ADDR_RECV		(1 << 7)
+#define SER_RS485_ADDR_DEST		(1 << 8)
 
-	__u32	delay_rts_before_send;	/* Delay before send (milliseconds) */
-	__u32	delay_rts_after_send;	/* Delay after send (milliseconds) */
+	__u32	delay_rts_before_send;
+	__u32	delay_rts_after_send;
 
 	/* The fields below are defined by flags */
 	union {