1 // SPDX-License-Identifier: GPL-2.0 2 3 //! `register!` macro to define register layout and accessors. 4 //! 5 //! A single register typically includes several fields, which are accessed through a combination 6 //! of bit-shift and mask operations that introduce a class of potential mistakes, notably because 7 //! not all possible field values are necessarily valid. 8 //! 9 //! The `register!` macro in this module provides an intuitive and readable syntax for defining a 10 //! dedicated type for each register. Each such type comes with its own field accessors that can 11 //! return an error if a field's value is invalid. 12 13 /// Defines a dedicated type for a register with an absolute offset, including getter and setter 14 /// methods for its fields and methods to read and write it from an `Io` region. 15 /// 16 /// Example: 17 /// 18 /// ```no_run 19 /// register!(BOOT_0 @ 0x00000100, "Basic revision information about the GPU" { 20 /// 3:0 minor_revision as u8, "Minor revision of the chip"; 21 /// 7:4 major_revision as u8, "Major revision of the chip"; 22 /// 28:20 chipset as u32 ?=> Chipset, "Chipset model"; 23 /// }); 24 /// ``` 25 /// 26 /// This defines a `BOOT_0` type which can be read or written from offset `0x100` of an `Io` 27 /// region. It is composed of 3 fields, for instance `minor_revision` is made of the 4 least 28 /// significant bits of the register. Each field can be accessed and modified using accessor 29 /// methods: 30 /// 31 /// ```no_run 32 /// // Read from the register's defined offset (0x100). 33 /// let boot0 = BOOT_0::read(&bar); 34 /// pr_info!("chip revision: {}.{}", boot0.major_revision(), boot0.minor_revision()); 35 /// 36 /// // `Chipset::try_from` is called with the value of the `chipset` field and returns an 37 /// // error if it is invalid. 38 /// let chipset = boot0.chipset()?; 39 /// 40 /// // Update some fields and write the value back. 41 /// boot0.set_major_revision(3).set_minor_revision(10).write(&bar); 42 /// 43 /// // Or, just read and update the register in a single step: 44 /// BOOT_0::alter(&bar, |r| r.set_major_revision(3).set_minor_revision(10)); 45 /// ``` 46 /// 47 /// Fields are defined as follows: 48 /// 49 /// - `as <type>` simply returns the field value casted to <type>, typically `u32`, `u16`, `u8` or 50 /// `bool`. Note that `bool` fields must have a range of 1 bit. 51 /// - `as <type> => <into_type>` calls `<into_type>`'s `From::<<type>>` implementation and returns 52 /// the result. 53 /// - `as <type> ?=> <try_into_type>` calls `<try_into_type>`'s `TryFrom::<<type>>` implementation 54 /// and returns the result. This is useful with fields for which not all values are valid. 55 /// 56 /// The documentation strings are optional. If present, they will be added to the type's 57 /// definition, or the field getter and setter methods they are attached to. 58 /// 59 /// Putting a `+` before the address of the register makes it relative to a base: the `read` and 60 /// `write` methods take a `base` argument that is added to the specified address before access: 61 /// 62 /// ```no_run 63 /// register!(CPU_CTL @ +0x0000010, "CPU core control" { 64 /// 0:0 start as bool, "Start the CPU core"; 65 /// }); 66 /// 67 /// // Flip the `start` switch for the CPU core which base address is at `CPU_BASE`. 68 /// let cpuctl = CPU_CTL::read(&bar, CPU_BASE); 69 /// pr_info!("CPU CTL: {:#x}", cpuctl); 70 /// cpuctl.set_start(true).write(&bar, CPU_BASE); 71 /// ``` 72 /// 73 /// It is also possible to create a alias register by using the `=> ALIAS` syntax. This is useful 74 /// for cases where a register's interpretation depends on the context: 75 /// 76 /// ```no_run 77 /// register!(SCRATCH @ 0x00000200, "Scratch register" { 78 /// 31:0 value as u32, "Raw value"; 79 /// }); 80 /// 81 /// register!(SCRATCH_BOOT_STATUS => SCRATCH, "Boot status of the firmware" { 82 /// 0:0 completed as bool, "Whether the firmware has completed booting"; 83 /// }); 84 /// ``` 85 /// 86 /// In this example, `SCRATCH_0_BOOT_STATUS` uses the same I/O address as `SCRATCH`, while also 87 /// providing its own `completed` field. 88 macro_rules! register { 89 // Creates a register at a fixed offset of the MMIO space. 90 ($name:ident @ $offset:literal $(, $comment:literal)? { $($fields:tt)* } ) => { 91 register!(@core $name $(, $comment)? { $($fields)* } ); 92 register!(@io $name @ $offset); 93 }; 94 95 // Creates an alias register of fixed offset register `alias` with its own fields. 96 ($name:ident => $alias:ident $(, $comment:literal)? { $($fields:tt)* } ) => { 97 register!(@core $name $(, $comment)? { $($fields)* } ); 98 register!(@io $name @ $alias::OFFSET); 99 }; 100 101 // Creates a register at a relative offset from a base address. 102 ($name:ident @ + $offset:literal $(, $comment:literal)? { $($fields:tt)* } ) => { 103 register!(@core $name $(, $comment)? { $($fields)* } ); 104 register!(@io $name @ + $offset); 105 }; 106 107 // Creates an alias register of relative offset register `alias` with its own fields. 108 ($name:ident => + $alias:ident $(, $comment:literal)? { $($fields:tt)* } ) => { 109 register!(@core $name $(, $comment)? { $($fields)* } ); 110 register!(@io $name @ + $alias::OFFSET); 111 }; 112 113 // All rules below are helpers. 114 115 // Defines the wrapper `$name` type, as well as its relevant implementations (`Debug`, `BitOr`, 116 // and conversion to the value type) and field accessor methods. 117 (@core $name:ident $(, $comment:literal)? { $($fields:tt)* }) => { 118 $( 119 #[doc=$comment] 120 )? 121 #[repr(transparent)] 122 #[derive(Clone, Copy, Default)] 123 pub(crate) struct $name(u32); 124 125 // TODO[REGA]: display the raw hex value, then the value of all the fields. This requires 126 // matching the fields, which will complexify the syntax considerably... 127 impl ::core::fmt::Debug for $name { 128 fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result { 129 f.debug_tuple(stringify!($name)) 130 .field(&format_args!("0x{0:x}", &self.0)) 131 .finish() 132 } 133 } 134 135 impl ::core::ops::BitOr for $name { 136 type Output = Self; 137 138 fn bitor(self, rhs: Self) -> Self::Output { 139 Self(self.0 | rhs.0) 140 } 141 } 142 143 impl ::core::convert::From<$name> for u32 { 144 fn from(reg: $name) -> u32 { 145 reg.0 146 } 147 } 148 149 register!(@fields_dispatcher $name { $($fields)* }); 150 }; 151 152 // Captures the fields and passes them to all the implementers that require field information. 153 // 154 // Used to simplify the matching rules for implementers, so they don't need to match the entire 155 // complex fields rule even though they only make use of part of it. 156 (@fields_dispatcher $name:ident { 157 $($hi:tt:$lo:tt $field:ident as $type:tt 158 $(?=> $try_into_type:ty)? 159 $(=> $into_type:ty)? 160 $(, $comment:literal)? 161 ; 162 )* 163 } 164 ) => { 165 register!(@field_accessors $name { 166 $( 167 $hi:$lo $field as $type 168 $(?=> $try_into_type)? 169 $(=> $into_type)? 170 $(, $comment)? 171 ; 172 )* 173 }); 174 }; 175 176 // Defines all the field getter/methods methods for `$name`. 177 ( 178 @field_accessors $name:ident { 179 $($hi:tt:$lo:tt $field:ident as $type:tt 180 $(?=> $try_into_type:ty)? 181 $(=> $into_type:ty)? 182 $(, $comment:literal)? 183 ; 184 )* 185 } 186 ) => { 187 $( 188 register!(@check_field_bounds $hi:$lo $field as $type); 189 )* 190 191 #[allow(dead_code)] 192 impl $name { 193 $( 194 register!(@field_accessor $name $hi:$lo $field as $type 195 $(?=> $try_into_type)? 196 $(=> $into_type)? 197 $(, $comment)? 198 ; 199 ); 200 )* 201 } 202 }; 203 204 // Boolean fields must have `$hi == $lo`. 205 (@check_field_bounds $hi:tt:$lo:tt $field:ident as bool) => { 206 #[allow(clippy::eq_op)] 207 const _: () = { 208 ::kernel::build_assert!( 209 $hi == $lo, 210 concat!("boolean field `", stringify!($field), "` covers more than one bit") 211 ); 212 }; 213 }; 214 215 // Non-boolean fields must have `$hi >= $lo`. 216 (@check_field_bounds $hi:tt:$lo:tt $field:ident as $type:tt) => { 217 #[allow(clippy::eq_op)] 218 const _: () = { 219 ::kernel::build_assert!( 220 $hi >= $lo, 221 concat!("field `", stringify!($field), "`'s MSB is smaller than its LSB") 222 ); 223 }; 224 }; 225 226 // Catches fields defined as `bool` and convert them into a boolean value. 227 ( 228 @field_accessor $name:ident $hi:tt:$lo:tt $field:ident as bool => $into_type:ty 229 $(, $comment:literal)?; 230 ) => { 231 register!( 232 @leaf_accessor $name $hi:$lo $field 233 { |f| <$into_type>::from(if f != 0 { true } else { false }) } 234 $into_type => $into_type $(, $comment)?; 235 ); 236 }; 237 238 // Shortcut for fields defined as `bool` without the `=>` syntax. 239 ( 240 @field_accessor $name:ident $hi:tt:$lo:tt $field:ident as bool $(, $comment:literal)?; 241 ) => { 242 register!(@field_accessor $name $hi:$lo $field as bool => bool $(, $comment)?;); 243 }; 244 245 // Catches the `?=>` syntax for non-boolean fields. 246 ( 247 @field_accessor $name:ident $hi:tt:$lo:tt $field:ident as $type:tt ?=> $try_into_type:ty 248 $(, $comment:literal)?; 249 ) => { 250 register!(@leaf_accessor $name $hi:$lo $field 251 { |f| <$try_into_type>::try_from(f as $type) } $try_into_type => 252 ::core::result::Result< 253 $try_into_type, 254 <$try_into_type as ::core::convert::TryFrom<$type>>::Error 255 > 256 $(, $comment)?;); 257 }; 258 259 // Catches the `=>` syntax for non-boolean fields. 260 ( 261 @field_accessor $name:ident $hi:tt:$lo:tt $field:ident as $type:tt => $into_type:ty 262 $(, $comment:literal)?; 263 ) => { 264 register!(@leaf_accessor $name $hi:$lo $field 265 { |f| <$into_type>::from(f as $type) } $into_type => $into_type $(, $comment)?;); 266 }; 267 268 // Shortcut for non-boolean fields defined without the `=>` or `?=>` syntax. 269 ( 270 @field_accessor $name:ident $hi:tt:$lo:tt $field:ident as $type:tt 271 $(, $comment:literal)?; 272 ) => { 273 register!(@field_accessor $name $hi:$lo $field as $type => $type $(, $comment)?;); 274 }; 275 276 // Generates the accessor methods for a single field. 277 ( 278 @leaf_accessor $name:ident $hi:tt:$lo:tt $field:ident 279 { $process:expr } $to_type:ty => $res_type:ty $(, $comment:literal)?; 280 ) => { 281 ::kernel::macros::paste!( 282 const [<$field:upper _RANGE>]: ::core::ops::RangeInclusive<u8> = $lo..=$hi; 283 const [<$field:upper _MASK>]: u32 = ((((1 << $hi) - 1) << 1) + 1) - ((1 << $lo) - 1); 284 const [<$field:upper _SHIFT>]: u32 = Self::[<$field:upper _MASK>].trailing_zeros(); 285 ); 286 287 $( 288 #[doc="Returns the value of this field:"] 289 #[doc=$comment] 290 )? 291 #[inline] 292 pub(crate) fn $field(self) -> $res_type { 293 ::kernel::macros::paste!( 294 const MASK: u32 = $name::[<$field:upper _MASK>]; 295 const SHIFT: u32 = $name::[<$field:upper _SHIFT>]; 296 ); 297 let field = ((self.0 & MASK) >> SHIFT); 298 299 $process(field) 300 } 301 302 ::kernel::macros::paste!( 303 $( 304 #[doc="Sets the value of this field:"] 305 #[doc=$comment] 306 )? 307 #[inline] 308 pub(crate) fn [<set_ $field>](mut self, value: $to_type) -> Self { 309 const MASK: u32 = $name::[<$field:upper _MASK>]; 310 const SHIFT: u32 = $name::[<$field:upper _SHIFT>]; 311 let value = (u32::from(value) << SHIFT) & MASK; 312 self.0 = (self.0 & !MASK) | value; 313 314 self 315 } 316 ); 317 }; 318 319 // Generates the IO accessors for a fixed offset register. 320 (@io $name:ident @ $offset:expr) => { 321 #[allow(dead_code)] 322 impl $name { 323 pub(crate) const OFFSET: usize = $offset; 324 325 /// Read the register from its address in `io`. 326 #[inline] 327 pub(crate) fn read<const SIZE: usize, T>(io: &T) -> Self where 328 T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>, 329 { 330 Self(io.read32($offset)) 331 } 332 333 /// Write the value contained in `self` to the register address in `io`. 334 #[inline] 335 pub(crate) fn write<const SIZE: usize, T>(self, io: &T) where 336 T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>, 337 { 338 io.write32(self.0, $offset) 339 } 340 341 /// Read the register from its address in `io` and run `f` on its value to obtain a new 342 /// value to write back. 343 #[inline] 344 pub(crate) fn alter<const SIZE: usize, T, F>( 345 io: &T, 346 f: F, 347 ) where 348 T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>, 349 F: ::core::ops::FnOnce(Self) -> Self, 350 { 351 let reg = f(Self::read(io)); 352 reg.write(io); 353 } 354 } 355 }; 356 357 // Generates the IO accessors for a relative offset register. 358 (@io $name:ident @ + $offset:literal) => { 359 #[allow(dead_code)] 360 impl $name { 361 pub(crate) const OFFSET: usize = $offset; 362 363 #[inline] 364 pub(crate) fn read<const SIZE: usize, T>( 365 io: &T, 366 base: usize, 367 ) -> Self where 368 T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>, 369 { 370 Self(io.read32(base + $offset)) 371 } 372 373 #[inline] 374 pub(crate) fn write<const SIZE: usize, T>( 375 self, 376 io: &T, 377 base: usize, 378 ) where 379 T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>, 380 { 381 io.write32(self.0, base + $offset) 382 } 383 384 #[inline] 385 pub(crate) fn alter<const SIZE: usize, T, F>( 386 io: &T, 387 base: usize, 388 f: F, 389 ) where 390 T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>, 391 F: ::core::ops::FnOnce(Self) -> Self, 392 { 393 let reg = f(Self::read(io, base)); 394 reg.write(io, base); 395 } 396 } 397 }; 398 } 399