Implement SpiOperation::TransferInPlace based on SpidevTransfer::read_write_in_place()

Fixes #120

Author: jannic

Cargo.toml

@@ -31,7 +31,7 @@ sysfs_gpio = { version = "0.6.1", optional = true }
 i2cdev = { version = "0.6.0", optional = true }
 nb = "1"
 serialport = { version = "4.2.0", default-features = false, optional = true }
-spidev = { version = "0.6.0", optional = true }
+spidev = { version = "0.7.0", optional = true, git = "https://github.com/rust-embedded/rust-spidev.git", rev = "refs/pull/49/head" }
 nix = { version = "0.27.1", optional = true }
 tokio = { version = "1", default-features = false, optional = true }
 

src/spi.rs

@@ -173,9 +173,8 @@ mod embedded_hal_impl {
         }
 
         fn transfer_in_place(&mut self, words: &mut [u8]) -> Result<(), Self::Error> {
-            let tx = words.to_owned();
             self.0
-                .transfer(&mut SpidevTransfer::read_write(&tx, words))
+                .transfer(&mut SpidevTransfer::read_write_in_place(words))
                 .map_err(|err| SPIError { err })
         }
 
@@ -214,11 +213,7 @@ mod embedded_hal_impl {
                         }
                     },
                     SpiOperation::TransferInPlace(buf) => {
-                        let tx = unsafe {
-                            let p = buf.as_ptr();
-                            std::slice::from_raw_parts(p, buf.len())
-                        };
-                        transfers.push(SpidevTransfer::read_write(tx, buf));
+                        transfers.push(SpidevTransfer::read_write_in_place(buf));
                     }
                     SpiOperation::DelayNs(ns) => {
                         let us = {