rust: add PL011 device model

This commit adds a re-implementation of hw/char/pl011.c in Rust.

How to build:

1. Configure a QEMU build with:
   --enable-system --target-list=aarch64-softmmu --enable-rust
2. Launching a VM with qemu-system-aarch64 should use the Rust version
   of the pl011 device

Co-authored-by: Junjie Mao <[email protected]>
Co-authored-by: Paolo Bonzini <[email protected]>
Signed-off-by: Junjie Mao <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
Signed-off-by: Manos Pitsidianakis <[email protected]>
Link: https://lore.kernel.org/r/6ec1d4fb8db2a1d7ba94c73e65d9770371b7857d.1727961605.git.manos.pitsidianakis@linaro.org
Signed-off-by: Paolo Bonzini <[email protected]>

MAINTAINERS

@@ -1139,6 +1139,11 @@ F: include/hw/*/microbit*.h
 F: tests/qtest/microbit-test.c
 F: docs/system/arm/nrf.rst
 
+ARM PL011 Rust device
+M: Manos Pitsidianakis <[email protected]>
+S: Maintained
+F: rust/hw/char/pl011/
+
 AVR Machines
 -------------
 

hw/arm/Kconfig

@@ -20,7 +20,8 @@ config ARM_VIRT
     select PCI_EXPRESS
     select PCI_EXPRESS_GENERIC_BRIDGE
     select PFLASH_CFI01
-    select PL011 # UART
+    select PL011 if !HAVE_RUST # UART
+    select X_PL011_RUST if HAVE_RUST # UART
     select PL031 # RTC
     select PL061 # GPIO
     select GPIO_PWR
@@ -73,7 +74,8 @@ config HIGHBANK
     select AHCI
     select ARM_TIMER # sp804
     select ARM_V7M
-    select PL011 # UART
+    select PL011 if !HAVE_RUST # UART
+    select X_PL011_RUST if HAVE_RUST # UART
     select PL022 # SPI
     select PL031 # RTC
     select PL061 # GPIO
@@ -86,7 +88,8 @@ config INTEGRATOR
     depends on TCG && ARM
     select ARM_TIMER
     select INTEGRATOR_DEBUG
-    select PL011 # UART
+    select PL011 if !HAVE_RUST # UART
+    select X_PL011_RUST if HAVE_RUST # UART
     select PL031 # RTC
     select PL041 # audio
     select PL050 # keyboard/mouse
@@ -104,7 +107,8 @@ config MUSCA
     default y
     depends on TCG && ARM
     select ARMSSE
-    select PL011
+    select PL011 if !HAVE_RUST # UART
+    select X_PL011_RUST if HAVE_RUST # UART
     select PL031
     select SPLIT_IRQ
     select UNIMP
@@ -169,7 +173,8 @@ config REALVIEW
     select WM8750 # audio codec
     select LSI_SCSI_PCI
     select PCI
-    select PL011  # UART
+    select PL011 if !HAVE_RUST # UART
+    select X_PL011_RUST if HAVE_RUST # UART
     select PL031  # RTC
     select PL041  # audio codec
     select PL050  # keyboard/mouse
@@ -194,7 +199,8 @@ config SBSA_REF
     select PCI_EXPRESS
     select PCI_EXPRESS_GENERIC_BRIDGE
     select PFLASH_CFI01
-    select PL011 # UART
+    select PL011 if !HAVE_RUST # UART
+    select X_PL011_RUST if HAVE_RUST # UART
     select PL031 # RTC
     select PL061 # GPIO
     select USB_XHCI_SYSBUS
@@ -218,7 +224,8 @@ config STELLARIS
     select ARM_V7M
     select CMSDK_APB_WATCHDOG
     select I2C
-    select PL011 # UART
+    select PL011 if !HAVE_RUST # UART
+    select X_PL011_RUST if HAVE_RUST # UART
     select PL022 # SPI
     select PL061 # GPIO
     select SSD0303 # OLED display
@@ -278,7 +285,8 @@ config VEXPRESS
     select ARM_TIMER # sp804
     select LAN9118
     select PFLASH_CFI01
-    select PL011 # UART
+    select PL011 if !HAVE_RUST # UART
+    select X_PL011_RUST if HAVE_RUST # UART
     select PL041 # audio codec
     select PL181  # display
     select REALVIEW
@@ -362,7 +370,8 @@ config RASPI
     default y
     depends on TCG && ARM
     select FRAMEBUFFER
-    select PL011 # UART
+    select PL011 if !HAVE_RUST # UART
+    select X_PL011_RUST if HAVE_RUST # UART
     select SDHCI
     select USB_DWC2
     select BCM2835_SPI
@@ -437,7 +446,8 @@ config XLNX_VERSAL
     select ARM_GIC
     select CPU_CLUSTER
     select DEVICE_TREE
-    select PL011
+    select PL011 if !HAVE_RUST # UART
+    select X_PL011_RUST if HAVE_RUST # UART
     select CADENCE
     select VIRTIO_MMIO
     select UNIMP

meson.build

@@ -3512,6 +3512,7 @@ qom_ss = ss.source_set()
 system_ss = ss.source_set()
 specific_fuzz_ss = ss.source_set()
 specific_ss = ss.source_set()
+rust_devices_ss = ss.source_set()
 stub_ss = ss.source_set()
 trace_ss = ss.source_set()
 user_ss = ss.source_set()
@@ -4059,6 +4060,29 @@ foreach target : target_dirs
   arch_srcs += target_specific.sources()
   arch_deps += target_specific.dependencies()
 
+  if have_rust and have_system
+    target_rust = rust_devices_ss.apply(config_target, strict: false)
+    crates = []
+    foreach dep : target_rust.dependencies()
+      crates += dep.get_variable('crate')
+    endforeach
+    if crates.length() > 0
+      rlib_rs = custom_target('rust_' + target.underscorify() + '.rs',
+                              output: 'rust_' + target.underscorify() + '.rs',
+                              command: [find_program('scripts/rust/rust_root_crate.sh')] + crates,
+                              capture: true,
+                              build_by_default: true,
+                              build_always_stale: true)
+      rlib = static_library('rust_' + target.underscorify(),
+                            rlib_rs,
+                            dependencies: target_rust.dependencies(),
+                            override_options: ['rust_std=2021', 'build.rust_std=2021'],
+                            rust_args: rustc_args,
+                            rust_abi: 'c')
+      arch_deps += declare_dependency(link_whole: [rlib])
+    endif
+  endif
+
   # allow using headers from the dependencies but do not include the sources,
   # because this emulator only needs those in "objects".  For external
   # dependencies, the full dependency is included below in the executable.

rust/Kconfig

@@ -0,0 +1 @@
+source hw/Kconfig

rust/hw/Kconfig

@@ -0,0 +1,2 @@
+# devices Kconfig
+source char/Kconfig

rust/hw/char/Kconfig

@@ -0,0 +1,3 @@
+config X_PL011_RUST
+    bool
+    default y if HAVE_RUST

rust/hw/char/meson.build

@@ -0,0 +1 @@
+subdir('pl011')

rust/hw/char/pl011/.gitignore

@@ -0,0 +1,2 @@
+# Ignore generated bindings file overrides.
+src/bindings.rs.inc

rust/hw/char/pl011/Cargo.toml

@@ -0,0 +1,26 @@
+[package]
+name = "pl011"
+version = "0.1.0"
+edition = "2021"
+authors = ["Manos Pitsidianakis <[email protected]>"]
+license = "GPL-2.0-or-later"
+readme = "README.md"
+homepage = "https://www.qemu.org"
+description = "pl011 device model for QEMU"
+repository = "https://gitlab.com/epilys/rust-for-qemu"
+resolver = "2"
+publish = false
+keywords = []
+categories = []
+
+[lib]
+crate-type = ["staticlib"]
+
+[dependencies]
+bilge = { version = "0.2.0" }
+bilge-impl = { version = "0.2.0" }
+qemu_api = { path = "../../../qemu-api" }
+qemu_api_macros = { path = "../../../qemu-api-macros" }
+
+# Do not include in any global workspace
+[workspace]

rust/hw/char/pl011/README.md

@@ -0,0 +1,31 @@
+# PL011 QEMU Device Model
+
+This library implements a device model for the PrimeCell® UART (PL011)
+device in QEMU.
+
+## Build static lib
+
+Host build target must be explicitly specified:
+
+```sh
+cargo build --target x86_64-unknown-linux-gnu
+```
+
+Replace host target triplet if necessary.
+
+## Generate Rust documentation
+
+To generate docs for this crate, including private items:
+
+```sh
+cargo doc --no-deps --document-private-items --target x86_64-unknown-linux-gnu
+```
+
+To include direct dependencies like `bilge` (bitmaps for register types):
+
+```sh
+cargo tree --depth 1 -e normal --prefix none \
+ | cut -d' ' -f1 \
+ | xargs printf -- '-p %s\n' \
+ | xargs cargo doc --no-deps --document-private-items --target x86_64-unknown-linux-gnu
+```

rust/hw/char/pl011/meson.build

@@ -0,0 +1,26 @@
+subproject('bilge-0.2-rs', required: true)
+subproject('bilge-impl-0.2-rs', required: true)
+
+bilge_dep = dependency('bilge-0.2-rs')
+bilge_impl_dep = dependency('bilge-impl-0.2-rs')
+
+_libpl011_rs = static_library(
+  'pl011',
+  files('src/lib.rs'),
+  override_options: ['rust_std=2021', 'build.rust_std=2021'],
+  rust_abi: 'rust',
+  dependencies: [
+    bilge_dep,
+    bilge_impl_dep,
+    qemu_api,
+    qemu_api_macros,
+  ],
+)
+
+rust_devices_ss.add(when: 'CONFIG_X_PL011_RUST', if_true: [declare_dependency(
+  link_whole: [_libpl011_rs],
+  # Putting proc macro crates in `dependencies` is necessary for Meson to find
+  # them when compiling the root per-target static rust lib.
+  dependencies: [bilge_impl_dep, qemu_api_macros],
+  variables: {'crate': 'pl011'},
+)])