Prepare for 0.4.0 release.

Change-Id: If66ac4f06d639a0e6db653713915758fd6e822d5
Signed-off-by: Andrew Walbran <qwandor@google.com>
diff --git a/CHANGELOG.md b/CHANGELOG.md
index af0078f..016990d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,6 @@
 # Changelog
 
-## Unreleased
+## 0.4.0
 
 ### Breaking changes
 
diff --git a/Cargo.lock b/Cargo.lock
index f18c17b..2ec57ed 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1,10 +1,10 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
-version = 3
+version = 4
 
 [[package]]
 name = "arm-pl011-uart"
-version = "0.3.2"
+version = "0.4.0"
 dependencies = [
  "bitflags",
  "embedded-hal-nb",
diff --git a/Cargo.toml b/Cargo.toml
index af3bd4a..5383b6d 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -3,7 +3,7 @@
 
 [package]
 name = "arm-pl011-uart"
-version = "0.3.2"
+version = "0.4.0"
 authors = [
     "Balint Dobszay <balint.dobszay@arm.com>",
     "Imre Kis <imre.kis@arm.com>",