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 ( 91 $name:ident @ $offset:literal $(, $comment:literal)? { 92 $($fields:tt)* 93 } 94 ) => { 95 register!(@common $name $(, $comment)?); 96 register!(@field_accessors $name { $($fields)* }); 97 register!(@io $name @ $offset); 98 }; 99 100 // Creates a alias register of fixed offset register `alias` with its own fields. 101 ( 102 $name:ident => $alias:ident $(, $comment:literal)? { 103 $($fields:tt)* 104 } 105 ) => { 106 register!(@common $name $(, $comment)?); 107 register!(@field_accessors $name { $($fields)* }); 108 register!(@io $name @ $alias::OFFSET); 109 }; 110 111 // Creates a register at a relative offset from a base address. 112 ( 113 $name:ident @ + $offset:literal $(, $comment:literal)? { 114 $($fields:tt)* 115 } 116 ) => { 117 register!(@common $name $(, $comment)?); 118 register!(@field_accessors $name { $($fields)* }); 119 register!(@io $name @ + $offset); 120 }; 121 122 // Creates a alias register of relative offset register `alias` with its own fields. 123 ( 124 $name:ident => + $alias:ident $(, $comment:literal)? { 125 $($fields:tt)* 126 } 127 ) => { 128 register!(@common $name $(, $comment)?); 129 register!(@field_accessors $name { $($fields)* }); 130 register!(@io $name @ + $alias::OFFSET); 131 }; 132 133 // All rules below are helpers. 134 135 // Defines the wrapper `$name` type, as well as its relevant implementations (`Debug`, `BitOr`, 136 // and conversion to regular `u32`). 137 (@common $name:ident $(, $comment:literal)?) => { 138 $( 139 #[doc=$comment] 140 )? 141 #[repr(transparent)] 142 #[derive(Clone, Copy, Default)] 143 pub(crate) struct $name(u32); 144 145 // TODO[REGA]: display the raw hex value, then the value of all the fields. This requires 146 // matching the fields, which will complexify the syntax considerably... 147 impl ::core::fmt::Debug for $name { 148 fn fmt(&self, f: &mut ::core::fmt::Formatter<'_>) -> ::core::fmt::Result { 149 f.debug_tuple(stringify!($name)) 150 .field(&format_args!("0x{0:x}", &self.0)) 151 .finish() 152 } 153 } 154 155 impl ::core::ops::BitOr for $name { 156 type Output = Self; 157 158 fn bitor(self, rhs: Self) -> Self::Output { 159 Self(self.0 | rhs.0) 160 } 161 } 162 163 impl ::core::convert::From<$name> for u32 { 164 fn from(reg: $name) -> u32 { 165 reg.0 166 } 167 } 168 }; 169 170 // Defines all the field getter/methods methods for `$name`. 171 ( 172 @field_accessors $name:ident { 173 $($hi:tt:$lo:tt $field:ident as $type:tt 174 $(?=> $try_into_type:ty)? 175 $(=> $into_type:ty)? 176 $(, $comment:literal)? 177 ; 178 )* 179 } 180 ) => { 181 $( 182 register!(@check_field_bounds $hi:$lo $field as $type); 183 )* 184 185 #[allow(dead_code)] 186 impl $name { 187 $( 188 register!(@field_accessor $name $hi:$lo $field as $type 189 $(?=> $try_into_type)? 190 $(=> $into_type)? 191 $(, $comment)? 192 ; 193 ); 194 )* 195 } 196 }; 197 198 // Boolean fields must have `$hi == $lo`. 199 (@check_field_bounds $hi:tt:$lo:tt $field:ident as bool) => { 200 #[allow(clippy::eq_op)] 201 const _: () = { 202 ::kernel::build_assert!( 203 $hi == $lo, 204 concat!("boolean field `", stringify!($field), "` covers more than one bit") 205 ); 206 }; 207 }; 208 209 // Non-boolean fields must have `$hi >= $lo`. 210 (@check_field_bounds $hi:tt:$lo:tt $field:ident as $type:tt) => { 211 #[allow(clippy::eq_op)] 212 const _: () = { 213 ::kernel::build_assert!( 214 $hi >= $lo, 215 concat!("field `", stringify!($field), "`'s MSB is smaller than its LSB") 216 ); 217 }; 218 }; 219 220 // Catches fields defined as `bool` and convert them into a boolean value. 221 ( 222 @field_accessor $name:ident $hi:tt:$lo:tt $field:ident as bool => $into_type:ty 223 $(, $comment:literal)?; 224 ) => { 225 register!( 226 @leaf_accessor $name $hi:$lo $field 227 { |f| <$into_type>::from(if f != 0 { true } else { false }) } 228 $into_type => $into_type $(, $comment)?; 229 ); 230 }; 231 232 // Shortcut for fields defined as `bool` without the `=>` syntax. 233 ( 234 @field_accessor $name:ident $hi:tt:$lo:tt $field:ident as bool $(, $comment:literal)?; 235 ) => { 236 register!(@field_accessor $name $hi:$lo $field as bool => bool $(, $comment)?;); 237 }; 238 239 // Catches the `?=>` syntax for non-boolean fields. 240 ( 241 @field_accessor $name:ident $hi:tt:$lo:tt $field:ident as $type:tt ?=> $try_into_type:ty 242 $(, $comment:literal)?; 243 ) => { 244 register!(@leaf_accessor $name $hi:$lo $field 245 { |f| <$try_into_type>::try_from(f as $type) } $try_into_type => 246 ::core::result::Result< 247 $try_into_type, 248 <$try_into_type as ::core::convert::TryFrom<$type>>::Error 249 > 250 $(, $comment)?;); 251 }; 252 253 // Catches the `=>` syntax for non-boolean fields. 254 ( 255 @field_accessor $name:ident $hi:tt:$lo:tt $field:ident as $type:tt => $into_type:ty 256 $(, $comment:literal)?; 257 ) => { 258 register!(@leaf_accessor $name $hi:$lo $field 259 { |f| <$into_type>::from(f as $type) } $into_type => $into_type $(, $comment)?;); 260 }; 261 262 // Shortcut for fields defined as non-`bool` without the `=>` or `?=>` syntax. 263 ( 264 @field_accessor $name:ident $hi:tt:$lo:tt $field:ident as $type:tt 265 $(, $comment:literal)?; 266 ) => { 267 register!(@field_accessor $name $hi:$lo $field as $type => $type $(, $comment)?;); 268 }; 269 270 // Generates the accessor methods for a single field. 271 ( 272 @leaf_accessor $name:ident $hi:tt:$lo:tt $field:ident 273 { $process:expr } $to_type:ty => $res_type:ty $(, $comment:literal)?; 274 ) => { 275 ::kernel::macros::paste!( 276 const [<$field:upper _RANGE>]: ::core::ops::RangeInclusive<u8> = $lo..=$hi; 277 const [<$field:upper _MASK>]: u32 = ((((1 << $hi) - 1) << 1) + 1) - ((1 << $lo) - 1); 278 const [<$field:upper _SHIFT>]: u32 = Self::[<$field:upper _MASK>].trailing_zeros(); 279 ); 280 281 $( 282 #[doc="Returns the value of this field:"] 283 #[doc=$comment] 284 )? 285 #[inline] 286 pub(crate) fn $field(self) -> $res_type { 287 ::kernel::macros::paste!( 288 const MASK: u32 = $name::[<$field:upper _MASK>]; 289 const SHIFT: u32 = $name::[<$field:upper _SHIFT>]; 290 ); 291 let field = ((self.0 & MASK) >> SHIFT); 292 293 $process(field) 294 } 295 296 ::kernel::macros::paste!( 297 $( 298 #[doc="Sets the value of this field:"] 299 #[doc=$comment] 300 )? 301 #[inline] 302 pub(crate) fn [<set_ $field>](mut self, value: $to_type) -> Self { 303 const MASK: u32 = $name::[<$field:upper _MASK>]; 304 const SHIFT: u32 = $name::[<$field:upper _SHIFT>]; 305 let value = (u32::from(value) << SHIFT) & MASK; 306 self.0 = (self.0 & !MASK) | value; 307 308 self 309 } 310 ); 311 }; 312 313 // Creates the IO accessors for a fixed offset register. 314 (@io $name:ident @ $offset:expr) => { 315 #[allow(dead_code)] 316 impl $name { 317 pub(crate) const OFFSET: usize = $offset; 318 319 #[inline] 320 pub(crate) fn read<const SIZE: usize, T>(io: &T) -> Self where 321 T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>, 322 { 323 Self(io.read32($offset)) 324 } 325 326 #[inline] 327 pub(crate) fn write<const SIZE: usize, T>(self, io: &T) where 328 T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>, 329 { 330 io.write32(self.0, $offset) 331 } 332 333 #[inline] 334 pub(crate) fn alter<const SIZE: usize, T, F>( 335 io: &T, 336 f: F, 337 ) where 338 T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>, 339 F: ::core::ops::FnOnce(Self) -> Self, 340 { 341 let reg = f(Self::read(io)); 342 reg.write(io); 343 } 344 } 345 }; 346 347 // Create the IO accessors for a relative offset register. 348 (@io $name:ident @ + $offset:literal) => { 349 #[allow(dead_code)] 350 impl $name { 351 pub(crate) const OFFSET: usize = $offset; 352 353 #[inline] 354 pub(crate) fn read<const SIZE: usize, T>( 355 io: &T, 356 base: usize, 357 ) -> Self where 358 T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>, 359 { 360 Self(io.read32(base + $offset)) 361 } 362 363 #[inline] 364 pub(crate) fn write<const SIZE: usize, T>( 365 self, 366 io: &T, 367 base: usize, 368 ) where 369 T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>, 370 { 371 io.write32(self.0, base + $offset) 372 } 373 374 #[inline] 375 pub(crate) fn alter<const SIZE: usize, T, F>( 376 io: &T, 377 base: usize, 378 f: F, 379 ) where 380 T: ::core::ops::Deref<Target = ::kernel::io::Io<SIZE>>, 381 F: ::core::ops::FnOnce(Self) -> Self, 382 { 383 let reg = f(Self::read(io, base)); 384 reg.write(io, base); 385 } 386 } 387 }; 388 } 389