fsl_add_inb_buffer(9)

💖 fsl_add_inb_buffer 💖

okay so you're in the Kernel API Manual (yes, the big one, the iconic one) and this page is all about fsl_add_inb_buffer — one tiny function with main character energy. it does exactly one job and it does it slayfully. let's get into it 🫶

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✨ SYNOPSIS ✨

int fsl_add_inb_buffer (struct rio_mport *mport , int mbox , void *buf );

three args, one int coming back at you. short. sweet. to the point. we love a signature that doesn't overstay its welcome 💅

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🎀 ARGUMENTS 🎀

• mport — the master port that's implementing the inbound message unit. like, this is the port, the one with the message unit energy. you gotta hand it over first.
• mbox — the inbound mailbox number. which mailbox are we talking to? that one. you tell it which one.
• buf — the buffer you're adding to the inbound queue. this is the actual payload, the little guy going into the queue. treat it right bestie 🥺

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🌸 DESCRIPTION 🌸

so what does it actually do? it adds the buf buffer to the MPC85xx inbound message queue. that's it. that's the whole vibe.

it returns 0 on success or -EINVAL on failure. no cap, that's the full return story — you either get that clean 0 (slay) or you get -EINVAL (not slay, but at least it's honest about it) 😭

ngl, keep an eye on that return value. 0 = we ate. -EINVAL = something in your args said no. either way, check it — don't just assume bestie 💀

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🦋 SEE ALSO 🦋

okay the friend group is huge, this function travels in a pack. all of these live in the kernel file ./arch/powerpc/sysdev/fsl_rmu.c:

• fsl_rio_tx_handler(9)
• fsl_rio_rx_handler(9)
• fsl_rio_dbell_handler(9)
• fsl_rio_port_write_handler(9)
• fsl_rio_pw_enable(9)
• fsl_rio_port_write_init(9)
• fsl_rio_doorbell_send(9)
• fsl_add_outb_message(9)
• fsl_open_outb_mbox(9)
• fsl_close_outb_mbox(9)
• fsl_open_inb_mbox(9)
• fsl_close_inb_mbox(9)
• fsl_get_inb_message(9)
• fsl_rio_doorbell_init(9)

literally the whole squad, go read them, they're all linked and they all ate 🔥

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and that's the page bestie!! short one, but she's got range 💜 also obligatory credits moment: this came out of ./arch/powerpc/sysdev and it's dated October 2026, so yeah, future-flavored kernel lore. go forth and add those buffers 🎀✨