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// Copyright 2019 The Chromium OS Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
use super::xhci_abi::{Error as TrbError, NormalTrb, TransferDescriptor, TrbCast, TrbType};
use std::fmt::{self, Display};
use sys_util::{GuestAddress, GuestMemory, GuestMemoryError};
#[derive(Debug)]
pub enum Error {
ReadGuestMemory(GuestMemoryError),
WriteGuestMemory(GuestMemoryError),
UnknownTrbType(TrbError),
CastTrb(TrbError),
BadTrbType(TrbType),
}
type Result<T> = std::result::Result<T, Error>;
impl Display for Error {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
use self::Error::*;
match self {
ReadGuestMemory(e) => write!(f, "cannot read guest memory: {}", e),
WriteGuestMemory(e) => write!(f, "cannot write guest memory: {}", e),
UnknownTrbType(e) => write!(f, "unknown trb type: {}", e),
CastTrb(e) => write!(f, "cannot cast trb: {}", e),
BadTrbType(t) => write!(f, "should not build buffer from trb type: {:?}", t),
}
}
}
/// See xHCI spec 3.2.8 for scatter/gather transfer. It's used in bulk/interrupt transfers. See
/// 3.2.10 for details.
pub struct ScatterGatherBuffer {
mem: GuestMemory,
td: TransferDescriptor,
}
impl ScatterGatherBuffer {
/// Create a new buffer from transfer descriptor.
pub fn new(mem: GuestMemory, td: TransferDescriptor) -> Result<ScatterGatherBuffer> {
for atrb in &td {
let trb_type = atrb.trb.trb_type().map_err(Error::UnknownTrbType)?;
if trb_type != TrbType::Normal
&& trb_type != TrbType::DataStage
&& trb_type != TrbType::Isoch
{
return Err(Error::BadTrbType(trb_type));
}
}
Ok(ScatterGatherBuffer { mem, td })
}
/// Total len of this buffer.
pub fn len(&self) -> Result<usize> {
let mut total_len = 0usize;
for atrb in &self.td {
total_len += atrb
.trb
.cast::<NormalTrb>()
.map_err(Error::CastTrb)?
.get_trb_transfer_length() as usize;
}
Ok(total_len)
}
/// Read content to buffer, return number of bytes read.
pub fn read(&self, buffer: &mut [u8]) -> Result<usize> {
let mut total_size = 0usize;
let mut offset = 0;
for atrb in &self.td {
let normal_trb = atrb.trb.cast::<NormalTrb>().map_err(Error::CastTrb)?;
let len = normal_trb.get_trb_transfer_length() as usize;
let buffer_len = {
if offset == buffer.len() {
return Ok(total_size);
}
if buffer.len() > offset + len {
len
} else {
buffer.len() - offset
}
};
let buffer_end = offset + buffer_len;
let cur_buffer = &mut buffer[offset..buffer_end];
offset = buffer_end;
total_size += self
.mem
.read_at_addr(cur_buffer, GuestAddress(normal_trb.get_data_buffer()))
.map_err(Error::ReadGuestMemory)?;
}
Ok(total_size)
}
/// Write content from buffer, return number of bytes written.
pub fn write(&self, buffer: &[u8]) -> Result<usize> {
let mut total_size = 0usize;
let mut offset = 0;
for atrb in &self.td {
let normal_trb = atrb.trb.cast::<NormalTrb>().map_err(Error::CastTrb)?;
let len = normal_trb.get_trb_transfer_length() as usize;
let buffer_len = {
if offset == buffer.len() {
return Ok(total_size);
}
if buffer.len() > offset + len {
len
} else {
buffer.len() - offset
}
};
let buffer_end = offset + buffer_len;
let cur_buffer = &buffer[offset..buffer_end];
offset = buffer_end;
total_size += self
.mem
.write_at_addr(cur_buffer, GuestAddress(normal_trb.get_data_buffer()))
.map_err(Error::WriteGuestMemory)?;
}
Ok(total_size)
}
}
#[cfg(test)]
mod test {
use super::*;
use crate::usb::xhci::xhci_abi::{AddressedTrb, Trb};
#[test]
fn scatter_gather_buffer_test() {
let gm = GuestMemory::new(&vec![(GuestAddress(0), 0x1000)]).unwrap();
let mut td = TransferDescriptor::new();
// In this td, we are going to have scatter buffer at 0x100, length 4, 0x200 length 2 and
// 0x300 length 1.
let mut trb = Trb::new();
{
let ntrb = trb.cast_mut::<NormalTrb>().unwrap();
ntrb.set_trb_type(TrbType::Normal as u8);
ntrb.set_data_buffer(0x100);
ntrb.set_trb_transfer_length(4);
}
td.push(AddressedTrb { trb, gpa: 0 });
let mut trb = Trb::new();
{
let ntrb = trb.cast_mut::<NormalTrb>().unwrap();
ntrb.set_trb_type(TrbType::Normal as u8);
ntrb.set_data_buffer(0x200);
ntrb.set_trb_transfer_length(2);
}
td.push(AddressedTrb { trb, gpa: 0 });
let mut trb = Trb::new();
{
let ntrb = trb.cast_mut::<NormalTrb>().unwrap();
ntrb.set_trb_type(TrbType::Normal as u8);
ntrb.set_data_buffer(0x300);
ntrb.set_trb_transfer_length(1);
}
td.push(AddressedTrb { trb, gpa: 0 });
let buffer = ScatterGatherBuffer::new(gm.clone(), td).unwrap();
assert_eq!(buffer.len().unwrap(), 7);
let data_to_write: [u8; 7] = [7, 6, 5, 4, 3, 2, 1];
buffer.write(&data_to_write).unwrap();
let mut d = [0; 4];
gm.read_exact_at_addr(&mut d, GuestAddress(0x100)).unwrap();
assert_eq!(d, [7, 6, 5, 4]);;
gm.read_exact_at_addr(&mut d, GuestAddress(0x200)).unwrap();
assert_eq!(d, [3, 2, 0, 0]);;
gm.read_exact_at_addr(&mut d, GuestAddress(0x300)).unwrap();
assert_eq!(d, [1, 0, 0, 0]);;
let mut data_read = [0; 7];
buffer.read(&mut data_read).unwrap();
assert_eq!(data_to_write, data_read);
}
}
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