STRUCT NBPF_CHANNEL(9)

💅 struct nbpf_channel(9) — like, the whole kernel API manual, bestie

okay so this is the struct nbpf_channel(9) page from the Kernel API Manual (yes, section 9, we love a kernel-space moment ✨). it's all about one DMAC channel — a single channel of the DMA controller, broken down field by field so you know exactly what's vibing in there 🎀

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✨ NAME ✨

struct nbpf_channel — literally just one DMAC channel, that's the whole gig 💫

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🦋 SYNOPSIS 🦋

struct nbpf_channel {
    struct dma_chan dma_chan;
    struct tasklet_struct tasklet;
    void __iomem *base;
    struct nbpf_device *nbpf;
    char name[16];
    int irq;
    dma_addr_t slave_src_addr;
    size_t slave_src_width;
    size_t slave_src_burst;
    dma_addr_t slave_dst_addr;
    size_t slave_dst_width;
    size_t slave_dst_burst;
    unsigned int terminal;
    u32 dmarq_cfg;
    unsigned long flags;
    spinlock_t lock;
    struct list_head free_links;
    struct list_head free;
    struct list_head queued;
    struct list_head active;
    struct list_head done;
    struct list_head desc_page;
    struct nbpf_desc *running;
    bool paused;
};

like, that's the whole struct, no cap 👑

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🌸 Members 🌸

okay now the main character energy part — every single member, one by one, let's go 🫶

• dma_chan — the standard dmaengine channel object, the vanilla one everybody gets 🍦
• tasklet — this channel's own little tasklet, it's the one that runs the callbacks ⚡
• base — the register address base, where the registers live 📍
• nbpf — the DMAC itself, hi bestie 👋
• name — the IRQ name 🏷️
• irq — the IRQ number 🔢
• slave_src_addr — source address for slave DMA 📤
• slave_src_width — source slave data size, in bytes 📏
• slave_src_burst — maximum source slave burst size, in bytes 💥
• slave_dst_addr — destination address for slave DMA 📥
• slave_dst_width — destination slave data size, in bytes 📐
• slave_dst_burst — maximum destination slave burst size, in bytes 🌊
• terminal — the DMA terminal, assigned to this channel 🎯
• dmarq_cfg — DMA request line configuration: high / low, edge / level, for NBPF_CHAN_CFG 🎛️
• flags — configuration flags, straight from DT 🚩
• lock — protects the descriptor lists 🔒 (do not skip this one, fr fr)
• free_links — list of free link descriptors ⛓️
• free — list of free descriptors 🆓
• queued — list of queued descriptors 📋
• active — list of descriptors scheduled for processing 🏃‍♀️
• done — list of completed descriptors, waiting on post-processing ✅
• desc_page — list of additionally allocated descriptor pages, if there are any 📄
• running — the linked descriptor of the running transaction 🔥
• paused — are translations on this channel paused? 🤔 (a bool, so it's a yes/no vibe)

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👑 SEE ALSO 👑

• Kernel file ./drivers/dma/nbpfaxi.c and struct nbpf_desc(9) — go read those too, iykyk 📚

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heads up bestie: lock is there to protect the descriptor lists — that's the whole reason it exists, so don't be out here touching those lists without it 💀

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and that's a wrap on the struct nbpf_channel(9) page 🌈 — brought to you by the ./drivers/dma directory, dated October 2026, slaying in the Kernel API Manual forever 💖🎀🦋