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.
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
========================
6. References
=============
- [1] include/uapi/linux/serial.h
-
- [2] Documentation/devicetree/bindings/serial/rs485.txt
+ [1] Documentation/devicetree/bindings/serial/rs485.txt
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 {