STRUCT MIPS_EJTAG_FDC_TTY_PORT(9)

🦋 struct mips_ejtag_fdc_tty_port(9) 🦋

ok so this is a page from the Kernel API Manual, and bestie, it's literally the whole lore on one little wrapper struct 💅

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✨ NAME ✨

struct mips_ejtag_fdc_tty_port — the wrapper struct for an FDC tty_port, no cap 🫶

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🌸 SYNOPSIS 🌸

struct mips_ejtag_fdc_tty_port {
    struct tty_port                  port;
    struct mips_ejtag_fdc_tty       *driver;
    raw_spinlock_t rx_lock;
    void *rx_buf;
    spinlock_t xmit_lock;
    unsigned int                     xmit_cnt;
    unsigned int                     xmit_head;
    unsigned int                     xmit_tail;
    struct completion                xmit_empty;
 };

like… look at her. iconic. 👑

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🎀 Members 🎀

okay so here's the member-by-member rundown, and every single one is important so don't skip 🙈

• port — the TTY port data. that's the whole vibe of the thing 💖
• driver — the TTY driver. the main character, honestly ✨
• rx_lock — the lock for rx_buf. it protects between the hard interrupt and user context. it's also held during read SWITCH operations. so like, it's doing a lot of work, respect her 💅
• rx_buf — the read buffer. the little home where the incoming bytes chill 🏠
• xmit_lock — the lock for xmit_*, and for port.xmit_buf. it protects between user context and the kernel thread. and listen 👀 it gets used from the chars_in_buffer/write_room TTY callbacks, which are used during wait operations — so a mutex is unsuitable here. like, a mutex literally cannot sit with her. not the vibe. no cap 🔥
• xmit_cnt — the size of the xmit buffer contents 🍓
• xmit_head — the head of the xmit buffer, where data is written ✍️
• xmit_tail — the tail of the xmit buffer, where data is read 📖
• xmit_empty — the completion for the xmit buffer being empty. she's the "we're done here" notification 🎀

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🌈 SEE ALSO 🌈

bestie there is a whole friend group, go say hi to all of them 🫶

• Kernel file ./drivers/tty/mips_ejtag_fdc.c
• struct mips_ejtag_fdc_tty(9)
• struct fdc_word(9)
• struct mips_ejtag_fdc_console(9)
• mips_ejtag_fdc_put_chan(9)
• mips_ejtag_fdc_put(9)
• mips_ejtag_fdc_handle(9)
• mips_ejtag_fdc_isr(9)
• mips_ejtag_fdc_tty_timer(9)

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💀 reminder bestie: xmit_lock is a spinlock for a reason — it's reachable from chars_in_buffer/write_room callbacks during wait operations, so a mutex is unsuitable. don't go swapping it, i'm begging 🙏

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and that's the whole page!! sign-off time 🧚

this absolute banger lives in ./drivers/tty, dated October 2026, and it's filed under struct mips_...fdc_tty_port(9) in the Kernel API Manual. slay, go read the kernel source, ily 💜✨