STRUCT IOSM_MMIO(9)

🎀 STRUCT IOSM_MMIO 🎀

okay so bestie, welcome to the struct iosm_mmio(9) page from the Kernel API Manual — this is the whole entire vibe of an MMIO region that's been mapped to the doorbell scratchpad. yes, doorbell scratchpad. iconic name, no notes. 💅

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✨ SYNOPSIS ✨

like, here's the whole struct, bestie, exactly as it lives:

struct iosm_mmio {
    unsigned char __iomem *base;
    struct device *dev;
    struct mmio_offset offset;
    phys_addr_t context_info_addr;
    unsigned int chip_info_version;
    unsigned int chip_info_size;
    u32 mux_protocol;
    u8 has_ul_flow_credit:1, has_slp_no_prot:1, has_mcr_support:1;
 };

look at those bitfields at the end, living their best space-efficient life. we love a :1. 🫶

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🌸 MEMBERS 🌸

• base — the base address of the MMIO region. this is the main character address, fr fr. 👑
• dev — pointer to the device structure. gotta know which device we're talking to, obviously. 💖
• offset — the start offset. where the story begins. ✨
• context_info_addr — physical base address of the context info structure. physical, not virtual, don't get it twisted. 🎀
• chip_info_version — version of the chip info structure. iykyk. 🦋
• chip_info_size — size of the chip info structure. yes it has a size, everything has a size. 🌈
• mux_protocol — the mux protocol. that's it, that's the whole description, slay for being concise. ⭐
• has_ul_flow_credit — Ul flow credit support. it's a 1-bit yes/no situation. 💜
• has_slp_no_prot — device sleep no protocol support. also one bit, also doing its thing. 🌸
• has_mcr_support — usage of mcr support. one bit, one job, ate. 🔥

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🦋 SEE ALSO 🦋

the kernel file lives at ./drivers/net/wwan/iosm/iosm_ipc_mmio.h, and honestly the friend group here is:

• ipc_mmio_init(9)
• ipc_mmio_set_psi_addr_and_size(9)
• ipc_mmio_set_contex_info_addr(9)
• ipc_mmio_get_cp_version(9)
• ipc_mmio_get_rom_exit_code(9)
• ipc_mmio_get_exec_stage(9)
• ipc_mmio_get_ipc_state(9)
• ipc_mmio_copy_chip_info(9)
• ipc_mmio_config(9)
• ipc_mmio_update_cp_capability(9)

go read them, bestie, they're literally all part of the same saga. 📖

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ngl, the contex spelling in ipc_mmio_set_contex_info_addr(9) is exactly how it's written up there — do not "fix" it, that's canon. 💀

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okay that's the whole page, mwah 💋 — brought to you by the source tree at ./drivers/net/wwan/iosm, dated October 2026, filed under struct iosm_mmio(9) in the Kernel API Manual. go forth and doorbell-scratchpad responsibly. 🧚💖