Matthew Maurerrust: Add soc_device support057d44b10 months agoHistory
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// SPDX-License-Identifier: GPL-2.0 // Copyright (C) 2025 Google LLC. //! SoC Driver Abstraction.//!//! C header: [`include/linux/sys_soc.h`](srctree/include/linux/sys_soc.h) use crate::{    bindings,    error,    prelude::*,    str::CString,    types::Opaque, //};use core::ptr::NonNull; /// Attributes for a SoC device.////// These are both exported to userspace under /sys/devices/socX and provided to other drivers to/// match against via `soc_device_match` (not yet available in Rust) to enable quirks or/// device-specific support where necessary.////// All fields are freeform - they have no specific formatting, just defined meanings./// For example, the [`machine`](`Attributes::machine`) field could be "DB8500" or/// "Qualcomm Technologies, Inc. SM8560 HDK", but regardless it should identify a board or product.pub struct Attributes {    /// Should generally be a board ID or product ID. Examples    /// include DB8500 (ST-Ericsson) or "Qualcomm Technologies, inc. SM8560 HDK".    ///    /// If this field is not populated, the SoC infrastructure will try to populate it from    /// `/model` in the device tree.    pub machine: Option<CString>,    /// The broader class this SoC belongs to. Examples include ux500    /// (for DB8500) or Snapdragon (for SM8650).    ///    /// On chips with ARM firmware supporting SMCCC v1.2+, this may be a JEDEC JEP106 manufacturer    /// identification.    pub family: Option<CString>,    /// The manufacturing revision of the part. Frequently this is MAJOR.MINOR, but not always.    pub revision: Option<CString>,    /// Serial Number - uniquely identifies a specific SoC. If present, should be unique (buying a    /// replacement part should change it if present). This field cannot be matched on and is    /// solely present to export through /sys.    pub serial_number: Option<CString>,    /// SoC ID - identifies a specific SoC kind in question, sometimes more specifically than    /// `machine` if the same SoC is used in multiple products. Some devices use this to specify a    /// SoC name, e.g. "I.MX??", and others just print an ID number (e.g. Tegra and Qualcomm).    ///    /// On chips with ARM firmware supporting SMCCC v1.2+, this may be a JEDEC JEP106 manufacturer    /// identification (the family value) followed by a colon and then a 4-digit ID value.    pub soc_id: Option<CString>,} struct BuiltAttributes {    // While `inner` has pointers to `_backing`, it is to the interior of the `CStrings`, not    // `backing` itself, so it does not need to be pinned.    _backing: Attributes,    // `Opaque` makes us `!Unpin`, as the registration holds a pointer to `inner` when used.    inner: Opaque<bindings::soc_device_attribute>,} fn cstring_to_c(mcs: &Option<CString>) -> *const kernel::ffi::c_char {    mcs.as_ref()        .map(|cs| cs.as_char_ptr())        .unwrap_or(core::ptr::null())} impl BuiltAttributes {    fn as_mut_ptr(&self) -> *mut bindings::soc_device_attribute {        self.inner.get()    }} impl Attributes {    fn build(self) -> BuiltAttributes {        BuiltAttributes {            inner: Opaque::new(bindings::soc_device_attribute {                machine: cstring_to_c(&self.machine),                family: cstring_to_c(&self.family),                revision: cstring_to_c(&self.revision),                serial_number: cstring_to_c(&self.serial_number),                soc_id: cstring_to_c(&self.soc_id),                data: core::ptr::null(),                custom_attr_group: core::ptr::null(),            }),            _backing: self,        }    }} #[pin_data(PinnedDrop)]/// Registration handle for your soc_dev. If you let it go out of scope, your soc_dev will be/// unregistered.pub struct Registration {    #[pin]    attr: BuiltAttributes,    soc_dev: NonNull<bindings::soc_device>,} // SAFETY: We provide no operations through `&Registration`.unsafe impl Sync for Registration {} // SAFETY: All pointers are normal allocations, not thread-specific.unsafe impl Send for Registration {} #[pinned_drop]impl PinnedDrop for Registration {    fn drop(self: Pin<&mut Self>) {        // SAFETY: Device always contains a live pointer to a soc_device that can be unregistered        unsafe { bindings::soc_device_unregister(self.soc_dev.as_ptr()) }    }} impl Registration {    /// Register a new SoC device    pub fn new(attr: Attributes) -> impl PinInit<Self, Error> {        try_pin_init!(Self {            attr: attr.build(),            soc_dev: {                // SAFETY:                // * The struct provided through attr is backed by pinned data next to it,                //   so as long as attr lives, the strings pointed to by the struct will too.                // * `attr` is pinned, so the pinned data won't move.                // * If it returns a device, and so others may try to read this data, by                //   caller invariant, `attr` won't be released until the device is.                let raw_soc = error::from_err_ptr(unsafe {                    bindings::soc_device_register(attr.as_mut_ptr())                })?;                 NonNull::new(raw_soc).ok_or(EINVAL)?            },        }? Error)    }}