__ssp_transmit_char(9)

💅 __ssp_transmit_char — a kernel API manual moment

okay so bestie, we're in the kernel API manual, specifically section 9, and today's main character is __ssp_transmit_char ✨ it's a tiny little function that just... puts a byte in a FIFO. and honestly? iconic behaviour. no cap.

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🌸 NAME 🌸

__ssp_transmit_char — enqueue a byte to transmit onto the TX FIFO 🎀

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✨ SYNOPSIS ✨

void __ssp_transmit_char (struct sifive_serial_port *ssp , int ch );

like, that's the whole signature. void return, so it gives you nothing back — it's giving "I did the thing, don't ask questions" energy 💅

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🦋 ARGUMENTS 🦋

• ssp — pointer to a struct sifive_serial_port. this is your lil serial port buddy that you're transmitting on 🫶
• ch — the character to transmit. one (1) single character. that's it. that's the byte 💖

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👑 DESCRIPTION 👑

So what it actually does: it enqueues a byte ch onto the transmit FIFO, given a pointer ssp to the struct sifive_serial_port * you wanna transmit on. simple. slay. one byte, one FIFO, done ✨

⚠️ but bestie listen — the caller should first check to make sure the TXFIFO actually has space before calling this. the manual literally points you at sifive_serial_is_txfifo_full for that check. check first, transmit second, that's the rule 🙈

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🌈 CONTEXT 🌈

Any context. fr fr, that's it — any context at all. no restrictions, no "only from interrupt context" drama, nothing. go off 💀

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🎀 SEE ALSO 🎀

the full squad, no gatekeeping:

• Kernel file ./drivers/tty/serial/sifive.c
• struct sifive_serial_port(9)
• __ssp_early_writel(9)
• __ssp_early_readl(9)
• __ssp_writel(9)
• __ssp_readl(9)
• sifive_serial_is_txfifo_full(9)
• __ssp_transmit_chars(9)
• __ssp_enable_txwm(9)
• __ssp_enable_rxwm(9)
• __ssp_disable_txwm(9)
• __ssp_disable_rxwm(9)
• __ssp_receive_char(9)
• __ssp_receive_chars(9)
• __ssp_update_div(9)
• __ssp_update_baud_rate(9)
• __ssp_set_stop_bits(9)
• __ssp_wait_for_xmitr(9)
• sifive_serial_clk_notifier(9)

like a whole friend group of ssp functions, and you should lowkey go read them all 🧚

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and that's the page!! 💜 it lives over in ./drivers/tty/serial, dated October 2026, and it's titled __ssp_transmit_char(9) — mwah, that's a wrap, periodt 🍓✨