1 // Copyright 2023, The Android Open Source Project 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of the License at 6 // 7 // http://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 15 //! High-level FDT functions. 16 17 pub mod pci; 18 19 use core::ops::Range; 20 use libfdt::{self, Fdt, FdtError}; 21 22 /// Represents information about a SWIOTLB buffer. 23 #[derive(Debug)] 24 pub struct SwiotlbInfo { 25 /// The address of the SWIOTLB buffer, if available. 26 pub addr: Option<usize>, 27 /// The size of the SWIOTLB buffer. 28 pub size: usize, 29 /// The alignment of the SWIOTLB buffer, if available. 30 pub align: Option<usize>, 31 } 32 33 impl SwiotlbInfo { 34 /// Creates a `SwiotlbInfo` struct from the given device tree. new_from_fdt(fdt: &Fdt) -> libfdt::Result<Option<SwiotlbInfo>>35 pub fn new_from_fdt(fdt: &Fdt) -> libfdt::Result<Option<SwiotlbInfo>> { 36 let Some(node) = fdt.compatible_nodes(c"restricted-dma-pool")?.next() else { 37 return Ok(None); 38 }; 39 let (addr, size, align) = if let Some(mut reg) = node.reg()? { 40 let reg = reg.next().ok_or(FdtError::BadValue)?; 41 let size = reg.size.ok_or(FdtError::BadValue)?; 42 (Some(reg.addr.try_into().unwrap()), size.try_into().unwrap(), None) 43 } else { 44 let size = node.getprop_u64(c"size")?.ok_or(FdtError::NotFound)?; 45 let align = node.getprop_u64(c"alignment")?.ok_or(FdtError::NotFound)?; 46 (None, size.try_into().unwrap(), Some(align.try_into().unwrap())) 47 }; 48 Ok(Some(Self { addr, size, align })) 49 } 50 51 /// Returns the fixed range of memory mapped by the SWIOTLB buffer, if available. fixed_range(&self) -> Option<Range<usize>>52 pub fn fixed_range(&self) -> Option<Range<usize>> { 53 self.addr.map(|addr| addr..addr + self.size) 54 } 55 } 56