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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)
}
}