rust/kernel/i2c.rs - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0

 //! I2C Driver subsystem

 // I2C Driver abstractions.
 use crate::{
     acpi,
     container_of,
     device,
     device_id::{
         RawDeviceId,
         RawDeviceIdIndex, //
     },
     devres::Devres,
     driver,
     error::*,
     of,
     prelude::*,
     types::{
         AlwaysRefCounted,
         Opaque, //
     }, //
 };

 use core::{
     marker::PhantomData,
     mem::offset_of,
     ptr::{
         from_ref,
         NonNull, //
     }, //
 };

 use kernel::types::ARef;

 /// An I2C device id table.
 #[repr(transparent)]
 #[derive(Clone, Copy)]
 pub struct DeviceId(bindings::i2c_device_id);

 impl DeviceId {
     const I2C_NAME_SIZE: usize = 20;

     /// Create a new device id from an I2C 'id' string.
     #[inline(always)]
     pub const fn new(id: &'static CStr) -> Self {
         let src = id.to_bytes_with_nul();
         build_assert!(src.len() <= Self::I2C_NAME_SIZE, "ID exceeds 20 bytes");
         let mut i2c: bindings::i2c_device_id = pin_init::zeroed();
         let mut i = 0;
         while i < src.len() {
             i2c.name[i] = src[i];
             i += 1;
         }

         Self(i2c)
     }
 }

 // SAFETY: `DeviceId` is a `#[repr(transparent)]` wrapper of `i2c_device_id` and does not add
 // additional invariants, so it's safe to transmute to `RawType`.
 unsafe impl RawDeviceId for DeviceId {
     type RawType = bindings::i2c_device_id;
 }

 // SAFETY: `DRIVER_DATA_OFFSET` is the offset to the `driver_data` field.
 unsafe impl RawDeviceIdIndex for DeviceId {
     const DRIVER_DATA_OFFSET: usize = core::mem::offset_of!(bindings::i2c_device_id, driver_data);

     fn index(&self) -> usize {
         self.0.driver_data
     }
 }

 /// IdTable type for I2C
 pub type IdTable<T> = &'static dyn kernel::device_id::IdTable<DeviceId, T>;

 /// Create a I2C `IdTable` with its alias for modpost.
 #[macro_export]
 macro_rules! i2c_device_table {
     ($table_name:ident, $module_table_name:ident, $id_info_type: ty, $table_data: expr) => {
         const $table_name: $crate::device_id::IdArray<
             $crate::i2c::DeviceId,
             $id_info_type,
             { $table_data.len() },
         > = $crate::device_id::IdArray::new($table_data);

         $crate::module_device_table!("i2c", $module_table_name, $table_name);
     };
 }

 /// An adapter for the registration of I2C drivers.
 pub struct Adapter<T: Driver>(T);

 // SAFETY: A call to `unregister` for a given instance of `RegType` is guaranteed to be valid if
 // a preceding call to `register` has been successful.
 unsafe impl<T: Driver + 'static> driver::RegistrationOps for Adapter<T> {
     type RegType = bindings::i2c_driver;

     unsafe fn register(
         idrv: &Opaque<Self::RegType>,
         name: &'static CStr,
         module: &'static ThisModule,
     ) -> Result {
         build_assert!(
             T::ACPI_ID_TABLE.is_some() || T::OF_ID_TABLE.is_some() || T::I2C_ID_TABLE.is_some(),
             "At least one of ACPI/OF/Legacy tables must be present when registering an i2c driver"
         );

         let i2c_table = match T::I2C_ID_TABLE {
             Some(table) => table.as_ptr(),
             None => core::ptr::null(),
         };

         let of_table = match T::OF_ID_TABLE {
             Some(table) => table.as_ptr(),
             None => core::ptr::null(),
         };

         let acpi_table = match T::ACPI_ID_TABLE {
             Some(table) => table.as_ptr(),
             None => core::ptr::null(),
         };

         // SAFETY: It's safe to set the fields of `struct i2c_client` on initialization.
         unsafe {
             (*idrv.get()).driver.name = name.as_char_ptr();
             (*idrv.get()).probe = Some(Self::probe_callback);
             (*idrv.get()).remove = Some(Self::remove_callback);
             (*idrv.get()).shutdown = Some(Self::shutdown_callback);
             (*idrv.get()).id_table = i2c_table;
             (*idrv.get()).driver.of_match_table = of_table;
             (*idrv.get()).driver.acpi_match_table = acpi_table;
         }

         // SAFETY: `idrv` is guaranteed to be a valid `RegType`.
         to_result(unsafe { bindings::i2c_register_driver(module.0, idrv.get()) })
     }

     unsafe fn unregister(idrv: &Opaque<Self::RegType>) {
         // SAFETY: `idrv` is guaranteed to be a valid `RegType`.
         unsafe { bindings::i2c_del_driver(idrv.get()) }
     }
 }

 impl<T: Driver + 'static> Adapter<T> {
     extern "C" fn probe_callback(idev: *mut bindings::i2c_client) -> kernel::ffi::c_int {
         // SAFETY: The I2C bus only ever calls the probe callback with a valid pointer to a
         // `struct i2c_client`.
         //
         // INVARIANT: `idev` is valid for the duration of `probe_callback()`.
         let idev = unsafe { &*idev.cast::<I2cClient<device::CoreInternal>>() };

         let info =
             Self::i2c_id_info(idev).or_else(|| <Self as driver::Adapter>::id_info(idev.as_ref()));

         from_result(|| {
             let data = T::probe(idev, info);

             idev.as_ref().set_drvdata(data)?;
             Ok(0)
         })
     }

     extern "C" fn remove_callback(idev: *mut bindings::i2c_client) {
         // SAFETY: `idev` is a valid pointer to a `struct i2c_client`.
         let idev = unsafe { &*idev.cast::<I2cClient<device::CoreInternal>>() };

         // SAFETY: `remove_callback` is only ever called after a successful call to
         // `probe_callback`, hence it's guaranteed that `I2cClient::set_drvdata()` has been called
         // and stored a `Pin<KBox<T>>`.
         let data = unsafe { idev.as_ref().drvdata_obtain::<T>() };

         T::unbind(idev, data.as_ref());
     }

     extern "C" fn shutdown_callback(idev: *mut bindings::i2c_client) {
         // SAFETY: `shutdown_callback` is only ever called for a valid `idev`
         let idev = unsafe { &*idev.cast::<I2cClient<device::CoreInternal>>() };

         // SAFETY: `shutdown_callback` is only ever called after a successful call to
         // `probe_callback`, hence it's guaranteed that `Device::set_drvdata()` has been called
         // and stored a `Pin<KBox<T>>`.
         let data = unsafe { idev.as_ref().drvdata_obtain::<T>() };

         T::shutdown(idev, data.as_ref());
     }

     /// The [`i2c::IdTable`] of the corresponding driver.
     fn i2c_id_table() -> Option<IdTable<<Self as driver::Adapter>::IdInfo>> {
         T::I2C_ID_TABLE
     }

     /// Returns the driver's private data from the matching entry in the [`i2c::IdTable`], if any.
     ///
     /// If this returns `None`, it means there is no match with an entry in the [`i2c::IdTable`].
     fn i2c_id_info(dev: &I2cClient) -> Option<&'static <Self as driver::Adapter>::IdInfo> {
         let table = Self::i2c_id_table()?;

         // SAFETY:
         // - `table` has static lifetime, hence it's valid for reads
         // - `dev` is guaranteed to be valid while it's alive, and so is `dev.as_raw()`.
         let raw_id = unsafe { bindings::i2c_match_id(table.as_ptr(), dev.as_raw()) };

         if raw_id.is_null() {
             return None;
         }

         // SAFETY: `DeviceId` is a `#[repr(transparent)` wrapper of `struct i2c_device_id` and
         // does not add additional invariants, so it's safe to transmute.
         let id = unsafe { &*raw_id.cast::<DeviceId>() };

         Some(table.info(<DeviceId as RawDeviceIdIndex>::index(id)))
     }
 }

 impl<T: Driver + 'static> driver::Adapter for Adapter<T> {
     type IdInfo = T::IdInfo;

     fn of_id_table() -> Option<of::IdTable<Self::IdInfo>> {
         T::OF_ID_TABLE
     }

     fn acpi_id_table() -> Option<acpi::IdTable<Self::IdInfo>> {
         T::ACPI_ID_TABLE
     }
 }

 /// Declares a kernel module that exposes a single i2c driver.
 ///
 /// # Examples
 ///
 /// ```ignore
 /// kernel::module_i2c_driver! {
 ///     type: MyDriver,
 ///     name: "Module name",
 ///     authors: ["Author name"],
 ///     description: "Description",
 ///     license: "GPL v2",
 /// }
 /// ```
 #[macro_export]
 macro_rules! module_i2c_driver {
     ($($f:tt)*) => {
         $crate::module_driver!(<T>, $crate::i2c::Adapter<T>, { $($f)* });
     };
 }

 /// The i2c driver trait.
 ///
 /// Drivers must implement this trait in order to get a i2c driver registered.
 ///
 /// # Example
 ///
 ///```
 /// # use kernel::{acpi, bindings, c_str, device::Core, i2c, of};
 ///
 /// struct MyDriver;
 ///
 /// kernel::acpi_device_table!(
 ///     ACPI_TABLE,
 ///     MODULE_ACPI_TABLE,
 ///     <MyDriver as i2c::Driver>::IdInfo,
 ///     [
 ///         (acpi::DeviceId::new(c_str!("LNUXBEEF")), ())
 ///     ]
 /// );
 ///
 /// kernel::i2c_device_table!(
 ///     I2C_TABLE,
 ///     MODULE_I2C_TABLE,
 ///     <MyDriver as i2c::Driver>::IdInfo,
 ///     [
 ///          (i2c::DeviceId::new(c_str!("rust_driver_i2c")), ())
 ///     ]
 /// );
 ///
 /// kernel::of_device_table!(
 ///     OF_TABLE,
 ///     MODULE_OF_TABLE,
 ///     <MyDriver as i2c::Driver>::IdInfo,
 ///     [
 ///         (of::DeviceId::new(c_str!("test,device")), ())
 ///     ]
 /// );
 ///
 /// impl i2c::Driver for MyDriver {
 ///     type IdInfo = ();
 ///     const I2C_ID_TABLE: Option<i2c::IdTable<Self::IdInfo>> = Some(&I2C_TABLE);
 ///     const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = Some(&OF_TABLE);
 ///     const ACPI_ID_TABLE: Option<acpi::IdTable<Self::IdInfo>> = Some(&ACPI_TABLE);
 ///
 ///     fn probe(
 ///         _idev: &i2c::I2cClient<Core>,
 ///         _id_info: Option<&Self::IdInfo>,
 ///     ) -> impl PinInit<Self, Error> {
 ///         Err(ENODEV)
 ///     }
 ///
 ///     fn shutdown(_idev: &i2c::I2cClient<Core>, this: Pin<&Self>) {
 ///     }
 /// }
 ///```
 pub trait Driver: Send {
     /// The type holding information about each device id supported by the driver.
     // TODO: Use `associated_type_defaults` once stabilized:
     //
     // ```
     // type IdInfo: 'static = ();
     // ```
     type IdInfo: 'static;

     /// The table of device ids supported by the driver.
     const I2C_ID_TABLE: Option<IdTable<Self::IdInfo>> = None;

     /// The table of OF device ids supported by the driver.
     const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = None;

     /// The table of ACPI device ids supported by the driver.
     const ACPI_ID_TABLE: Option<acpi::IdTable<Self::IdInfo>> = None;

     /// I2C driver probe.
     ///
     /// Called when a new i2c client is added or discovered.
     /// Implementers should attempt to initialize the client here.
     fn probe(
         dev: &I2cClient<device::Core>,
         id_info: Option<&Self::IdInfo>,
     ) -> impl PinInit<Self, Error>;

     /// I2C driver shutdown.
     ///
     /// Called by the kernel during system reboot or power-off to allow the [`Driver`] to bring the
     /// [`I2cClient`] into a safe state. Implementing this callback is optional.
     ///
     /// Typical actions include stopping transfers, disabling interrupts, or resetting the hardware
     /// to prevent undesired behavior during shutdown.
     ///
     /// This callback is distinct from final resource cleanup, as the driver instance remains valid
     /// after it returns. Any deallocation or teardown of driver-owned resources should instead be
     /// handled in `Self::drop`.
     fn shutdown(dev: &I2cClient<device::Core>, this: Pin<&Self>) {
         let _ = (dev, this);
     }

     /// I2C driver unbind.
     ///
     /// Called when the [`I2cClient`] is unbound from its bound [`Driver`]. Implementing this
     /// callback is optional.
     ///
     /// This callback serves as a place for drivers to perform teardown operations that require a
     /// `&Device<Core>` or `&Device<Bound>` reference. For instance, drivers may try to perform I/O
     /// operations to gracefully tear down the device.
     ///
     /// Otherwise, release operations for driver resources should be performed in `Self::drop`.
     fn unbind(dev: &I2cClient<device::Core>, this: Pin<&Self>) {
         let _ = (dev, this);
     }
 }

 /// The i2c adapter representation.
 ///
 /// This structure represents the Rust abstraction for a C `struct i2c_adapter`. The
 /// implementation abstracts the usage of an existing C `struct i2c_adapter` that
 /// gets passed from the C side
 ///
 /// # Invariants
 ///
 /// A [`I2cAdapter`] instance represents a valid `struct i2c_adapter` created by the C portion of
 /// the kernel.
 #[repr(transparent)]
 pub struct I2cAdapter<Ctx: device::DeviceContext = device::Normal>(
     Opaque<bindings::i2c_adapter>,
     PhantomData<Ctx>,
 );

 impl<Ctx: device::DeviceContext> I2cAdapter<Ctx> {
     fn as_raw(&self) -> *mut bindings::i2c_adapter {
         self.0.get()
     }
 }

 impl I2cAdapter {
     /// Returns the I2C Adapter index.
     #[inline]
     pub fn index(&self) -> i32 {
         // SAFETY: `self.as_raw` is a valid pointer to a `struct i2c_adapter`.
         unsafe { (*self.as_raw()).nr }
     }

     /// Gets pointer to an `i2c_adapter` by index.
     pub fn get(index: i32) -> Result<ARef<Self>> {
         // SAFETY: `index` must refer to a valid I2C adapter; the kernel
         // guarantees that `i2c_get_adapter(index)` returns either a valid
         // pointer or NULL. `NonNull::new` guarantees the correct check.
         let adapter = NonNull::new(unsafe { bindings::i2c_get_adapter(index) }).ok_or(ENODEV)?;

         // SAFETY: `adapter` is non-null and points to a live `i2c_adapter`.
         // `I2cAdapter` is #[repr(transparent)], so this cast is valid.
         Ok(unsafe { (&*adapter.as_ptr().cast::<I2cAdapter<device::Normal>>()).into() })
     }
 }

 // SAFETY: `I2cAdapter` is a transparent wrapper of a type that doesn't depend on
 // `I2cAdapter`'s generic argument.
 kernel::impl_device_context_deref!(unsafe { I2cAdapter });
 kernel::impl_device_context_into_aref!(I2cAdapter);

 // SAFETY: Instances of `I2cAdapter` are always reference-counted.
 unsafe impl crate::types::AlwaysRefCounted for I2cAdapter {
     fn inc_ref(&self) {
         // SAFETY: The existence of a shared reference guarantees that the refcount is non-zero.
         unsafe { bindings::i2c_get_adapter(self.index()) };
     }

     unsafe fn dec_ref(obj: NonNull<Self>) {
         // SAFETY: The safety requirements guarantee that the refcount is non-zero.
         unsafe { bindings::i2c_put_adapter(obj.as_ref().as_raw()) }
     }
 }

 /// The i2c board info representation
 ///
 /// This structure represents the Rust abstraction for a C `struct i2c_board_info` structure,
 /// which is used for manual I2C client creation.
 #[repr(transparent)]
 pub struct I2cBoardInfo(bindings::i2c_board_info);

 impl I2cBoardInfo {
     const I2C_TYPE_SIZE: usize = 20;
     /// Create a new [`I2cBoardInfo`] for a kernel driver.
     #[inline(always)]
     pub const fn new(type_: &'static CStr, addr: u16) -> Self {
         let src = type_.to_bytes_with_nul();
         build_assert!(src.len() <= Self::I2C_TYPE_SIZE, "Type exceeds 20 bytes");
         let mut i2c_board_info: bindings::i2c_board_info = pin_init::zeroed();
         let mut i: usize = 0;
         while i < src.len() {
             i2c_board_info.type_[i] = src[i];
             i += 1;
         }

         i2c_board_info.addr = addr;
         Self(i2c_board_info)
     }

     fn as_raw(&self) -> *const bindings::i2c_board_info {
         from_ref(&self.0)
     }
 }

 /// The i2c client representation.
 ///
 /// This structure represents the Rust abstraction for a C `struct i2c_client`. The
 /// implementation abstracts the usage of an existing C `struct i2c_client` that
 /// gets passed from the C side
 ///
 /// # Invariants
 ///
 /// A [`I2cClient`] instance represents a valid `struct i2c_client` created by the C portion of
 /// the kernel.
 #[repr(transparent)]
 pub struct I2cClient<Ctx: device::DeviceContext = device::Normal>(
     Opaque<bindings::i2c_client>,
     PhantomData<Ctx>,
 );

 impl<Ctx: device::DeviceContext> I2cClient<Ctx> {
     fn as_raw(&self) -> *mut bindings::i2c_client {
         self.0.get()
     }
 }

 // SAFETY: `I2cClient` is a transparent wrapper of `struct i2c_client`.
 // The offset is guaranteed to point to a valid device field inside `I2cClient`.
 unsafe impl<Ctx: device::DeviceContext> device::AsBusDevice<Ctx> for I2cClient<Ctx> {
     const OFFSET: usize = offset_of!(bindings::i2c_client, dev);
 }

 // SAFETY: `I2cClient` is a transparent wrapper of a type that doesn't depend on
 // `I2cClient`'s generic argument.
 kernel::impl_device_context_deref!(unsafe { I2cClient });
 kernel::impl_device_context_into_aref!(I2cClient);

 // SAFETY: Instances of `I2cClient` are always reference-counted.
 unsafe impl AlwaysRefCounted for I2cClient {
     fn inc_ref(&self) {
         // SAFETY: The existence of a shared reference guarantees that the refcount is non-zero.
         unsafe { bindings::get_device(self.as_ref().as_raw()) };
     }

     unsafe fn dec_ref(obj: NonNull<Self>) {
         // SAFETY: The safety requirements guarantee that the refcount is non-zero.
         unsafe { bindings::put_device(&raw mut (*obj.as_ref().as_raw()).dev) }
     }
 }

 impl<Ctx: device::DeviceContext> AsRef<device::Device<Ctx>> for I2cClient<Ctx> {
     fn as_ref(&self) -> &device::Device<Ctx> {
         let raw = self.as_raw();
         // SAFETY: By the type invariant of `Self`, `self.as_raw()` is a pointer to a valid
         // `struct i2c_client`.
         let dev = unsafe { &raw mut (*raw).dev };

         // SAFETY: `dev` points to a valid `struct device`.
         unsafe { device::Device::from_raw(dev) }
     }
 }

 impl<Ctx: device::DeviceContext> TryFrom<&device::Device<Ctx>> for &I2cClient<Ctx> {
     type Error = kernel::error::Error;

     fn try_from(dev: &device::Device<Ctx>) -> Result<Self, Self::Error> {
         // SAFETY: By the type invariant of `Device`, `dev.as_raw()` is a valid pointer to a
         // `struct device`.
         if unsafe { bindings::i2c_verify_client(dev.as_raw()).is_null() } {
             return Err(EINVAL);
         }

         // SAFETY: We've just verified that the type of `dev` equals to
         // `bindings::i2c_client_type`, hence `dev` must be embedded in a valid
         // `struct i2c_client` as guaranteed by the corresponding C code.
         let idev = unsafe { container_of!(dev.as_raw(), bindings::i2c_client, dev) };

         // SAFETY: `idev` is a valid pointer to a `struct i2c_client`.
         Ok(unsafe { &*idev.cast() })
     }
 }

 // SAFETY: A `I2cClient` is always reference-counted and can be released from any thread.
 unsafe impl Send for I2cClient {}

 // SAFETY: `I2cClient` can be shared among threads because all methods of `I2cClient`
 // (i.e. `I2cClient<Normal>) are thread safe.
 unsafe impl Sync for I2cClient {}

 /// The registration of an i2c client device.
 ///
 /// This type represents the registration of a [`struct i2c_client`]. When an instance of this
 /// type is dropped, its respective i2c client device will be unregistered from the system.
 ///
 /// # Invariants
 ///
 /// `self.0` always holds a valid pointer to an initialized and registered
 /// [`struct i2c_client`].
 #[repr(transparent)]
 pub struct Registration(NonNull<bindings::i2c_client>);

 impl Registration {
     /// The C `i2c_new_client_device` function wrapper for manual I2C client creation.
     pub fn new<'a>(
         i2c_adapter: &I2cAdapter,
         i2c_board_info: &I2cBoardInfo,
         parent_dev: &'a device::Device<device::Bound>,
     ) -> impl PinInit<Devres<Self>, Error> + 'a {
         Devres::new(parent_dev, Self::try_new(i2c_adapter, i2c_board_info))
     }

     fn try_new(i2c_adapter: &I2cAdapter, i2c_board_info: &I2cBoardInfo) -> Result<Self> {
         // SAFETY: the kernel guarantees that `i2c_new_client_device()` returns either a valid
         // pointer or NULL. `from_err_ptr` separates errors. Following `NonNull::new`
         // checks for NULL.
         let raw_dev = from_err_ptr(unsafe {
             bindings::i2c_new_client_device(i2c_adapter.as_raw(), i2c_board_info.as_raw())
         })?;

         let dev_ptr = NonNull::new(raw_dev).ok_or(ENODEV)?;

         Ok(Self(dev_ptr))
     }
 }

 impl Drop for Registration {
     fn drop(&mut self) {
         // SAFETY: `Drop` is only called for a valid `Registration`, which by invariant
         // always contains a non-null pointer to an `i2c_client`.
         unsafe { bindings::i2c_unregister_device(self.0.as_ptr()) }
     }
 }

 // SAFETY: A `Registration` of a `struct i2c_client` can be released from any thread.
 unsafe impl Send for Registration {}

 // SAFETY: `Registration` offers no interior mutability (no mutation through &self
 // and no mutable access is exposed)
 unsafe impl Sync for Registration {}
	// SPDX-License-Identifier: GPL-2.0

	//! I2C Driver subsystem

	// I2C Driver abstractions.
	use crate::{
	acpi,
	container_of,
	device,
	device_id::{
	RawDeviceId,
	RawDeviceIdIndex, //
	},
	devres::Devres,
	driver,
	error::*,
	of,
	prelude::*,
	types::{
	AlwaysRefCounted,
	Opaque, //
	}, //
	};

	use core::{
	marker::PhantomData,
	mem::offset_of,
	ptr::{
	from_ref,
	NonNull, //
	}, //
	};

	use kernel::types::ARef;

	/// An I2C device id table.
	#[repr(transparent)]
	#[derive(Clone, Copy)]
	pub struct DeviceId(bindings::i2c_device_id);

	impl DeviceId {
	const I2C_NAME_SIZE: usize = 20;

	/// Create a new device id from an I2C 'id' string.
	#[inline(always)]
	pub const fn new(id: &'static CStr) -> Self {
	let src = id.to_bytes_with_nul();
	build_assert!(src.len() <= Self::I2C_NAME_SIZE, "ID exceeds 20 bytes");
	let mut i2c: bindings::i2c_device_id = pin_init::zeroed();
	let mut i = 0;
	while i < src.len() {
	i2c.name[i] = src[i];
	i += 1;
	}

	Self(i2c)
	}
	}

	// SAFETY: `DeviceId` is a `#[repr(transparent)]` wrapper of `i2c_device_id` and does not add
	// additional invariants, so it's safe to transmute to `RawType`.
	unsafe impl RawDeviceId for DeviceId {
	type RawType = bindings::i2c_device_id;
	}

	// SAFETY: `DRIVER_DATA_OFFSET` is the offset to the `driver_data` field.
	unsafe impl RawDeviceIdIndex for DeviceId {
	const DRIVER_DATA_OFFSET: usize = core::mem::offset_of!(bindings::i2c_device_id, driver_data);

	fn index(&self) -> usize {
	self.0.driver_data
	}
	}

	/// IdTable type for I2C
	pub type IdTable<T> = &'static dyn kernel::device_id::IdTable<DeviceId, T>;

	/// Create a I2C `IdTable` with its alias for modpost.
	#[macro_export]
	macro_rules! i2c_device_table {
	($table_name:ident, $module_table_name:ident, $id_info_type: ty, $table_data: expr) => {
	const $table_name: $crate::device_id::IdArray<
	$crate::i2c::DeviceId,
	$id_info_type,
	{ $table_data.len() },
	> = $crate::device_id::IdArray::new($table_data);

	$crate::module_device_table!("i2c", $module_table_name, $table_name);
	};
	}

	/// An adapter for the registration of I2C drivers.
	pub struct Adapter<T: Driver>(T);

	// SAFETY: A call to `unregister` for a given instance of `RegType` is guaranteed to be valid if
	// a preceding call to `register` has been successful.
	unsafe impl<T: Driver + 'static> driver::RegistrationOps for Adapter<T> {
	type RegType = bindings::i2c_driver;

	unsafe fn register(
	idrv: &Opaque<Self::RegType>,
	name: &'static CStr,
	module: &'static ThisModule,
	) -> Result {
	build_assert!(
	T::ACPI_ID_TABLE.is_some() \|\| T::OF_ID_TABLE.is_some() \|\| T::I2C_ID_TABLE.is_some(),
	"At least one of ACPI/OF/Legacy tables must be present when registering an i2c driver"
	);

	let i2c_table = match T::I2C_ID_TABLE {
	Some(table) => table.as_ptr(),
	None => core::ptr::null(),
	};

	let of_table = match T::OF_ID_TABLE {
	Some(table) => table.as_ptr(),
	None => core::ptr::null(),
	};

	let acpi_table = match T::ACPI_ID_TABLE {
	Some(table) => table.as_ptr(),
	None => core::ptr::null(),
	};

	// SAFETY: It's safe to set the fields of `struct i2c_client` on initialization.
	unsafe {
	(*idrv.get()).driver.name = name.as_char_ptr();
	(*idrv.get()).probe = Some(Self::probe_callback);
	(*idrv.get()).remove = Some(Self::remove_callback);
	(*idrv.get()).shutdown = Some(Self::shutdown_callback);
	(*idrv.get()).id_table = i2c_table;
	(*idrv.get()).driver.of_match_table = of_table;
	(*idrv.get()).driver.acpi_match_table = acpi_table;
	}

	// SAFETY: `idrv` is guaranteed to be a valid `RegType`.
	to_result(unsafe { bindings::i2c_register_driver(module.0, idrv.get()) })
	}

	unsafe fn unregister(idrv: &Opaque<Self::RegType>) {
	// SAFETY: `idrv` is guaranteed to be a valid `RegType`.
	unsafe { bindings::i2c_del_driver(idrv.get()) }
	}
	}

	impl<T: Driver + 'static> Adapter<T> {
	extern "C" fn probe_callback(idev: *mut bindings::i2c_client) -> kernel::ffi::c_int {
	// SAFETY: The I2C bus only ever calls the probe callback with a valid pointer to a
	// `struct i2c_client`.
	//
	// INVARIANT: `idev` is valid for the duration of `probe_callback()`.
	let idev = unsafe { &*idev.cast::<I2cClient<device::CoreInternal>>() };

	let info =
	Self::i2c_id_info(idev).or_else(\|\| <Self as driver::Adapter>::id_info(idev.as_ref()));

	from_result(\|\| {
	let data = T::probe(idev, info);

	idev.as_ref().set_drvdata(data)?;
	Ok(0)
	})
	}

	extern "C" fn remove_callback(idev: *mut bindings::i2c_client) {
	// SAFETY: `idev` is a valid pointer to a `struct i2c_client`.
	let idev = unsafe { &*idev.cast::<I2cClient<device::CoreInternal>>() };

	// SAFETY: `remove_callback` is only ever called after a successful call to
	// `probe_callback`, hence it's guaranteed that `I2cClient::set_drvdata()` has been called
	// and stored a `Pin<KBox<T>>`.
	let data = unsafe { idev.as_ref().drvdata_obtain::<T>() };

	T::unbind(idev, data.as_ref());
	}

	extern "C" fn shutdown_callback(idev: *mut bindings::i2c_client) {
	// SAFETY: `shutdown_callback` is only ever called for a valid `idev`
	let idev = unsafe { &*idev.cast::<I2cClient<device::CoreInternal>>() };

	// SAFETY: `shutdown_callback` is only ever called after a successful call to
	// `probe_callback`, hence it's guaranteed that `Device::set_drvdata()` has been called
	// and stored a `Pin<KBox<T>>`.
	let data = unsafe { idev.as_ref().drvdata_obtain::<T>() };

	T::shutdown(idev, data.as_ref());
	}

	/// The [`i2c::IdTable`] of the corresponding driver.
	fn i2c_id_table() -> Option<IdTable<<Self as driver::Adapter>::IdInfo>> {
	T::I2C_ID_TABLE
	}

	/// Returns the driver's private data from the matching entry in the [`i2c::IdTable`], if any.
	///
	/// If this returns `None`, it means there is no match with an entry in the [`i2c::IdTable`].
	fn i2c_id_info(dev: &I2cClient) -> Option<&'static <Self as driver::Adapter>::IdInfo> {
	let table = Self::i2c_id_table()?;

	// SAFETY:
	// - `table` has static lifetime, hence it's valid for reads
	// - `dev` is guaranteed to be valid while it's alive, and so is `dev.as_raw()`.
	let raw_id = unsafe { bindings::i2c_match_id(table.as_ptr(), dev.as_raw()) };

	if raw_id.is_null() {
	return None;
	}

	// SAFETY: `DeviceId` is a `#[repr(transparent)` wrapper of `struct i2c_device_id` and
	// does not add additional invariants, so it's safe to transmute.
	let id = unsafe { &*raw_id.cast::<DeviceId>() };

	Some(table.info(<DeviceId as RawDeviceIdIndex>::index(id)))
	}
	}

	impl<T: Driver + 'static> driver::Adapter for Adapter<T> {
	type IdInfo = T::IdInfo;

	fn of_id_table() -> Option<of::IdTable<Self::IdInfo>> {
	T::OF_ID_TABLE
	}

	fn acpi_id_table() -> Option<acpi::IdTable<Self::IdInfo>> {
	T::ACPI_ID_TABLE
	}
	}

	/// Declares a kernel module that exposes a single i2c driver.
	///
	/// # Examples
	///
	/// ```ignore
	/// kernel::module_i2c_driver! {
	/// type: MyDriver,
	/// name: "Module name",
	/// authors: ["Author name"],
	/// description: "Description",
	/// license: "GPL v2",
	/// }
	/// ```
	#[macro_export]
	macro_rules! module_i2c_driver {
	($($f:tt)*) => {
	$crate::module_driver!(<T>, $crate::i2c::Adapter<T>, { $($f)* });
	};
	}

	/// The i2c driver trait.
	///
	/// Drivers must implement this trait in order to get a i2c driver registered.
	///
	/// # Example
	///
	///```
	/// # use kernel::{acpi, bindings, c_str, device::Core, i2c, of};
	///
	/// struct MyDriver;
	///
	/// kernel::acpi_device_table!(
	/// ACPI_TABLE,
	/// MODULE_ACPI_TABLE,
	/// <MyDriver as i2c::Driver>::IdInfo,
	/// [
	/// (acpi::DeviceId::new(c_str!("LNUXBEEF")), ())
	/// ]
	/// );
	///
	/// kernel::i2c_device_table!(
	/// I2C_TABLE,
	/// MODULE_I2C_TABLE,
	/// <MyDriver as i2c::Driver>::IdInfo,
	/// [
	/// (i2c::DeviceId::new(c_str!("rust_driver_i2c")), ())
	/// ]
	/// );
	///
	/// kernel::of_device_table!(
	/// OF_TABLE,
	/// MODULE_OF_TABLE,
	/// <MyDriver as i2c::Driver>::IdInfo,
	/// [
	/// (of::DeviceId::new(c_str!("test,device")), ())
	/// ]
	/// );
	///
	/// impl i2c::Driver for MyDriver {
	/// type IdInfo = ();
	/// const I2C_ID_TABLE: Option<i2c::IdTable<Self::IdInfo>> = Some(&I2C_TABLE);
	/// const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = Some(&OF_TABLE);
	/// const ACPI_ID_TABLE: Option<acpi::IdTable<Self::IdInfo>> = Some(&ACPI_TABLE);
	///
	/// fn probe(
	/// _idev: &i2c::I2cClient<Core>,
	/// _id_info: Option<&Self::IdInfo>,
	/// ) -> impl PinInit<Self, Error> {
	/// Err(ENODEV)
	/// }
	///
	/// fn shutdown(_idev: &i2c::I2cClient<Core>, this: Pin<&Self>) {
	/// }
	/// }
	///```
	pub trait Driver: Send {
	/// The type holding information about each device id supported by the driver.
	// TODO: Use `associated_type_defaults` once stabilized:
	//
	// ```
	// type IdInfo: 'static = ();
	// ```
	type IdInfo: 'static;

	/// The table of device ids supported by the driver.
	const I2C_ID_TABLE: Option<IdTable<Self::IdInfo>> = None;

	/// The table of OF device ids supported by the driver.
	const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = None;

	/// The table of ACPI device ids supported by the driver.
	const ACPI_ID_TABLE: Option<acpi::IdTable<Self::IdInfo>> = None;

	/// I2C driver probe.
	///
	/// Called when a new i2c client is added or discovered.
	/// Implementers should attempt to initialize the client here.
	fn probe(
	dev: &I2cClient<device::Core>,
	id_info: Option<&Self::IdInfo>,
	) -> impl PinInit<Self, Error>;

	/// I2C driver shutdown.
	///
	/// Called by the kernel during system reboot or power-off to allow the [`Driver`] to bring the
	/// [`I2cClient`] into a safe state. Implementing this callback is optional.
	///
	/// Typical actions include stopping transfers, disabling interrupts, or resetting the hardware
	/// to prevent undesired behavior during shutdown.
	///
	/// This callback is distinct from final resource cleanup, as the driver instance remains valid
	/// after it returns. Any deallocation or teardown of driver-owned resources should instead be
	/// handled in `Self::drop`.
	fn shutdown(dev: &I2cClient<device::Core>, this: Pin<&Self>) {
	let _ = (dev, this);
	}

	/// I2C driver unbind.
	///
	/// Called when the [`I2cClient`] is unbound from its bound [`Driver`]. Implementing this
	/// callback is optional.
	///
	/// This callback serves as a place for drivers to perform teardown operations that require a
	/// `&Device<Core>` or `&Device<Bound>` reference. For instance, drivers may try to perform I/O
	/// operations to gracefully tear down the device.
	///
	/// Otherwise, release operations for driver resources should be performed in `Self::drop`.
	fn unbind(dev: &I2cClient<device::Core>, this: Pin<&Self>) {
	let _ = (dev, this);
	}
	}

	/// The i2c adapter representation.
	///
	/// This structure represents the Rust abstraction for a C `struct i2c_adapter`. The
	/// implementation abstracts the usage of an existing C `struct i2c_adapter` that
	/// gets passed from the C side
	///
	/// # Invariants
	///
	/// A [`I2cAdapter`] instance represents a valid `struct i2c_adapter` created by the C portion of
	/// the kernel.
	#[repr(transparent)]
	pub struct I2cAdapter<Ctx: device::DeviceContext = device::Normal>(
	Opaque<bindings::i2c_adapter>,
	PhantomData<Ctx>,
	);

	impl<Ctx: device::DeviceContext> I2cAdapter<Ctx> {
	fn as_raw(&self) -> *mut bindings::i2c_adapter {
	self.0.get()
	}
	}

	impl I2cAdapter {
	/// Returns the I2C Adapter index.
	#[inline]
	pub fn index(&self) -> i32 {
	// SAFETY: `self.as_raw` is a valid pointer to a `struct i2c_adapter`.
	unsafe { (*self.as_raw()).nr }
	}

	/// Gets pointer to an `i2c_adapter` by index.
	pub fn get(index: i32) -> Result<ARef<Self>> {
	// SAFETY: `index` must refer to a valid I2C adapter; the kernel
	// guarantees that `i2c_get_adapter(index)` returns either a valid
	// pointer or NULL. `NonNull::new` guarantees the correct check.
	let adapter = NonNull::new(unsafe { bindings::i2c_get_adapter(index) }).ok_or(ENODEV)?;

	// SAFETY: `adapter` is non-null and points to a live `i2c_adapter`.
	// `I2cAdapter` is #[repr(transparent)], so this cast is valid.
	Ok(unsafe { (&*adapter.as_ptr().cast::<I2cAdapter<device::Normal>>()).into() })
	}
	}

	// SAFETY: `I2cAdapter` is a transparent wrapper of a type that doesn't depend on
	// `I2cAdapter`'s generic argument.
	kernel::impl_device_context_deref!(unsafe { I2cAdapter });
	kernel::impl_device_context_into_aref!(I2cAdapter);

	// SAFETY: Instances of `I2cAdapter` are always reference-counted.
	unsafe impl crate::types::AlwaysRefCounted for I2cAdapter {
	fn inc_ref(&self) {
	// SAFETY: The existence of a shared reference guarantees that the refcount is non-zero.
	unsafe { bindings::i2c_get_adapter(self.index()) };
	}

	unsafe fn dec_ref(obj: NonNull<Self>) {
	// SAFETY: The safety requirements guarantee that the refcount is non-zero.
	unsafe { bindings::i2c_put_adapter(obj.as_ref().as_raw()) }
	}
	}

	/// The i2c board info representation
	///
	/// This structure represents the Rust abstraction for a C `struct i2c_board_info` structure,
	/// which is used for manual I2C client creation.
	#[repr(transparent)]
	pub struct I2cBoardInfo(bindings::i2c_board_info);

	impl I2cBoardInfo {
	const I2C_TYPE_SIZE: usize = 20;
	/// Create a new [`I2cBoardInfo`] for a kernel driver.
	#[inline(always)]
	pub const fn new(type_: &'static CStr, addr: u16) -> Self {
	let src = type_.to_bytes_with_nul();
	build_assert!(src.len() <= Self::I2C_TYPE_SIZE, "Type exceeds 20 bytes");
	let mut i2c_board_info: bindings::i2c_board_info = pin_init::zeroed();
	let mut i: usize = 0;
	while i < src.len() {
	i2c_board_info.type_[i] = src[i];
	i += 1;
	}

	i2c_board_info.addr = addr;
	Self(i2c_board_info)
	}

	fn as_raw(&self) -> *const bindings::i2c_board_info {
	from_ref(&self.0)
	}
	}

	/// The i2c client representation.
	///
	/// This structure represents the Rust abstraction for a C `struct i2c_client`. The
	/// implementation abstracts the usage of an existing C `struct i2c_client` that
	/// gets passed from the C side
	///
	/// # Invariants
	///
	/// A [`I2cClient`] instance represents a valid `struct i2c_client` created by the C portion of
	/// the kernel.
	#[repr(transparent)]
	pub struct I2cClient<Ctx: device::DeviceContext = device::Normal>(
	Opaque<bindings::i2c_client>,
	PhantomData<Ctx>,
	);

	impl<Ctx: device::DeviceContext> I2cClient<Ctx> {
	fn as_raw(&self) -> *mut bindings::i2c_client {
	self.0.get()
	}
	}

	// SAFETY: `I2cClient` is a transparent wrapper of `struct i2c_client`.
	// The offset is guaranteed to point to a valid device field inside `I2cClient`.
	unsafe impl<Ctx: device::DeviceContext> device::AsBusDevice<Ctx> for I2cClient<Ctx> {
	const OFFSET: usize = offset_of!(bindings::i2c_client, dev);
	}

	// SAFETY: `I2cClient` is a transparent wrapper of a type that doesn't depend on
	// `I2cClient`'s generic argument.
	kernel::impl_device_context_deref!(unsafe { I2cClient });
	kernel::impl_device_context_into_aref!(I2cClient);

	// SAFETY: Instances of `I2cClient` are always reference-counted.
	unsafe impl AlwaysRefCounted for I2cClient {
	fn inc_ref(&self) {
	// SAFETY: The existence of a shared reference guarantees that the refcount is non-zero.
	unsafe { bindings::get_device(self.as_ref().as_raw()) };
	}

	unsafe fn dec_ref(obj: NonNull<Self>) {
	// SAFETY: The safety requirements guarantee that the refcount is non-zero.
	unsafe { bindings::put_device(&raw mut (*obj.as_ref().as_raw()).dev) }
	}
	}

	impl<Ctx: device::DeviceContext> AsRef<device::Device<Ctx>> for I2cClient<Ctx> {
	fn as_ref(&self) -> &device::Device<Ctx> {
	let raw = self.as_raw();
	// SAFETY: By the type invariant of `Self`, `self.as_raw()` is a pointer to a valid
	// `struct i2c_client`.
	let dev = unsafe { &raw mut (*raw).dev };

	// SAFETY: `dev` points to a valid `struct device`.
	unsafe { device::Device::from_raw(dev) }
	}
	}

	impl<Ctx: device::DeviceContext> TryFrom<&device::Device<Ctx>> for &I2cClient<Ctx> {
	type Error = kernel::error::Error;

	fn try_from(dev: &device::Device<Ctx>) -> Result<Self, Self::Error> {
	// SAFETY: By the type invariant of `Device`, `dev.as_raw()` is a valid pointer to a
	// `struct device`.
	if unsafe { bindings::i2c_verify_client(dev.as_raw()).is_null() } {
	return Err(EINVAL);
	}

	// SAFETY: We've just verified that the type of `dev` equals to
	// `bindings::i2c_client_type`, hence `dev` must be embedded in a valid
	// `struct i2c_client` as guaranteed by the corresponding C code.
	let idev = unsafe { container_of!(dev.as_raw(), bindings::i2c_client, dev) };

	// SAFETY: `idev` is a valid pointer to a `struct i2c_client`.
	Ok(unsafe { &*idev.cast() })
	}
	}

	// SAFETY: A `I2cClient` is always reference-counted and can be released from any thread.
	unsafe impl Send for I2cClient {}

	// SAFETY: `I2cClient` can be shared among threads because all methods of `I2cClient`
	// (i.e. `I2cClient<Normal>) are thread safe.
	unsafe impl Sync for I2cClient {}

	/// The registration of an i2c client device.
	///
	/// This type represents the registration of a [`struct i2c_client`]. When an instance of this
	/// type is dropped, its respective i2c client device will be unregistered from the system.
	///
	/// # Invariants
	///
	/// `self.0` always holds a valid pointer to an initialized and registered
	/// [`struct i2c_client`].
	#[repr(transparent)]
	pub struct Registration(NonNull<bindings::i2c_client>);

	impl Registration {
	/// The C `i2c_new_client_device` function wrapper for manual I2C client creation.
	pub fn new<'a>(
	i2c_adapter: &I2cAdapter,
	i2c_board_info: &I2cBoardInfo,
	parent_dev: &'a device::Device<device::Bound>,
	) -> impl PinInit<Devres<Self>, Error> + 'a {
	Devres::new(parent_dev, Self::try_new(i2c_adapter, i2c_board_info))
	}

	fn try_new(i2c_adapter: &I2cAdapter, i2c_board_info: &I2cBoardInfo) -> Result<Self> {
	// SAFETY: the kernel guarantees that `i2c_new_client_device()` returns either a valid
	// pointer or NULL. `from_err_ptr` separates errors. Following `NonNull::new`
	// checks for NULL.
	let raw_dev = from_err_ptr(unsafe {
	bindings::i2c_new_client_device(i2c_adapter.as_raw(), i2c_board_info.as_raw())
	})?;

	let dev_ptr = NonNull::new(raw_dev).ok_or(ENODEV)?;

	Ok(Self(dev_ptr))
	}
	}

	impl Drop for Registration {
	fn drop(&mut self) {
	// SAFETY: `Drop` is only called for a valid `Registration`, which by invariant
	// always contains a non-null pointer to an `i2c_client`.
	unsafe { bindings::i2c_unregister_device(self.0.as_ptr()) }
	}
	}

	// SAFETY: A `Registration` of a `struct i2c_client` can be released from any thread.
	unsafe impl Send for Registration {}

	// SAFETY: `Registration` offers no interior mutability (no mutation through &self
	// and no mutable access is exposed)
	unsafe impl Sync for Registration {}