serial8250_em485_config(9)

💖 serial8250_em485_config(9) 💖

okay bestie, welcome to the Kernel API Manual entry for serial8250_em485_config — a whole little icon in the 8250 serial world, and honestly? she's carrying the team. 🫶

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✨ SYNOPSIS ✨

int serial8250_em485_config (struct uart_port *port , struct ktermios
*termios , struct serial_rs485 *rs485 );

like, three args, one int back, no drama. 💅

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🌸 ARGUMENTS 🌸

• port — the uart port. your main character. the uart in question. 🎀
• termios — a termios structure. yes the classic one, she's here too.
• rs485 — the rs485 settings, aka the whole reason we're gathered here today. ✨

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🦋 DESCRIPTION 🦋

so the way that this works is — serial8250_em485_config is the generic ->rs485_config() callback, and it's usable by 8250 uart drivers to activate rs485 settings in one very specific situation, bestie:

your uart is incapable of driving RTS as a Transmit Enable signal in hardware. 😭 like it just cannot do it natively. so instead of giving up, we rely on software emulation instead. slay. that's the whole vibe. 🔥

no cap, that's the point of her — she's the software-emulation fallback for hardware that can't do the RTS-as-TE thing in silicon. iconic behaviour honestly. 👑

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👑 SEE ALSO 👑

• the kernel file itself, go read her: ./drivers/tty/serial/8250/8250_port.c 📖
• serial8250_em485_init(9)
• serial8250_em485_destroy(9)
• serial8250_em485_stop_tx(9)
• serial8250_em485_start_tx(9)

the whole em485 friend group fr fr 🫶💖

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and that's the page!! tysm for reading my little kernel lore dump 🧚‍♀️✨ this came out of ./drivers/tty/serial/8250, dated October 2026, under the header serial8250_em485_config(9) — go forth and emulate that RTS, bestie 💜🌈