uart_insert_char(9)

🌸 uart_insert_char(9) — the Kernel API Manual, but make it bestie-friendly 🌸

okay so welcome to the Kernel API Manual entry for uart_insert_char(9), and honestly? it's a little one-pager and it ate 💅 let's get into it.

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✨ NAME ✨

uart_insert_char — push a char to the uart layer 🎀

like. you have a char. you want it in the uart layer. this is the function for that. slay.

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🦋 SYNOPSIS 🦋

void uart_insert_char (struct uart_port *port , unsigned int status ,
       unsigned int overrun , u8 ch , u8 flag );

five arguments, one void, zero drama. (well. okay. some drama, there's an overrun mask involved, keep reading 🫶)

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💖 ARGUMENTS 💖

• port — the corresponding port. your port. the port in question. main character port energy 👑
• status — the state of the serial port RX buffer (that's LSR for 8250, iykyk). basically the receipts of what the hardware is going through rn.
• overrun — a mask of overrun bits in status. yes, a mask, of the overrun bits, inside status. it's giving layered. it's giving onion. it's giving "please read the status carefully" 🧅✨
• ch — the character to push. the actual lil guy. the payload. the u8 of the hour 🍓
• flag — the flag for the character (check TTY_NORMAL and friends, they're a whole friend group 💜)

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🌈 DESCRIPTION 🌈

the user is responsible to call tty_flip_buffer_push when they are done with insertion. 👈 this is you. this is your job. nobody else is gonna do it for you, bestie 😭

so like, uart_insert_char pushes the char in, right? but it does not push the flip buffer for you. that's on you. once you're done inserting, you call tty_flip_buffer_push. no cap. don't forget, fr fr 🫶

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⭐ SEE ALSO ⭐

the whole squad, in the order the manpage lists them, no rosters edited ✅ and all of it lives in the kernel file ./drivers/tty/serial/serial_core.c:

• uart_write_wakeup(9)
• uart_update_timeout(9)
• uart_get_baud_rate(9)
• uart_get_divisor(9)
• uart_get_lsr_info(9)
• uart_console_write(9)
• uart_parse_earlycon(9)
• uart_parse_options(9)
• uart_set_options(9)
• uart_change_pm(9)
• uart_register_driver(9)
• uart_unregister_driver(9)
• serial_core_add_one_port(9)
• serial_core_remove_one_port(9)
• uart_match_port(9)
• uart_handle_dcd_change(9)
• uart_handle_cts_change(9)
• uart_try_toggle_sysrq(9)
• uart_get_rs485_mode(9)

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and that's the page!! mwah 💋 oh and the cute lil sign-off at the bottom says this one comes from ./drivers/tty/serial and it's dated October 2026 — iconic, timeless, periodt 🎀🦋✨