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| author | Ilpo Järvinen <ilpo.jarvinen@linux.intel.com> | 2022-06-24 23:42:09 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-06-27 15:44:20 +0300 |
| commit | 4f768e94774c58c9f7f54ebd38dadf172970046a (patch) | |
| tree | f237520975e9f0839fd2dbbd911d2681288f949e /include/uapi/linux/serial.h | |
| parent | ae50bb2752836277ae15aa4e9d99074d6d947946 (diff) | |
| download | linux-4f768e94774c58c9f7f54ebd38dadf172970046a.tar.xz | |
serial: Support for RS-485 multipoint addresses
Add support for RS-485 multipoint addressing using 9th bit [*]. The
addressing mode is configured through ->rs485_config().
ADDRB in termios indicates 9th bit addressing mode is enabled. In this
mode, 9th bit is used to indicate an address (byte) within the
communication line. ADDRB can only be enabled/disabled through
->rs485_config() that is also responsible for setting the destination and
receiver (filter) addresses.
Add traps to detect unwanted changes to struct serial_rs485 layout using
static_assert().
[*] Technically, RS485 is just an electronic spec and does not itself
specify the 9th bit addressing mode but 9th bit seems at least
"semi-standard" way to do addressing with RS485.
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220624204210.11112-6-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include/uapi/linux/serial.h')
| -rw-r--r-- | include/uapi/linux/serial.h | 20 |
1 files changed, 18 insertions, 2 deletions
diff --git a/include/uapi/linux/serial.h b/include/uapi/linux/serial.h index fa6b16e5fdd8..cea06924b295 100644 --- a/include/uapi/linux/serial.h +++ b/include/uapi/linux/serial.h @@ -126,10 +126,26 @@ struct serial_rs485 { #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 */ + __u32 delay_rts_before_send; /* Delay before send (milliseconds) */ __u32 delay_rts_after_send; /* Delay after send (milliseconds) */ - __u32 padding[5]; /* Memory is cheap, new structs - are a royal PITA .. */ + + /* The fields below are defined by flags */ + union { + __u32 padding[5]; /* Memory is cheap, new structs are a pain */ + + struct { + __u8 addr_recv; + __u8 addr_dest; + __u8 padding0[2]; + __u32 padding1[4]; + }; + }; }; /* |