[PATCH] rust: pl011: Allow NULL chardev argument to pl011_create()

[Peter Maydell <peter.maydell@linaro.org>]

It's valid for the caller to pass a NULL chardev to pl011_create();
this means "don't set the chardev property on the device", which
in turn means "act like there's no chardev". All the chardev
frontend APIs (in C, at least) accept a NULL pointer to mean
"do nothing".

This fixes some failures in 'make check-functional' when Rust support
is enabled.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
This is my first Rust related patch for QEMU, so I've
probably got something wrong here :-)
---
 rust/hw/char/pl011/src/device.rs | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/rust/hw/char/pl011/src/device.rs b/rust/hw/char/pl011/src/device.rs
index d0857b470c9..8098f762f4b 100644
--- a/rust/hw/char/pl011/src/device.rs
+++ b/rust/hw/char/pl011/src/device.rs
@@ -713,10 +713,12 @@ pub fn post_load(&self, _version_id: u32) -> Result<(), ()> {
     // SAFETY: The callers promise that they have owned references.
     // They do not gift them to pl011_create, so use `Owned::from`.
     let irq = unsafe { Owned::<IRQState>::from(&*irq) };
-    let chr = unsafe { Owned::<Chardev>::from(&*chr) };
 
     let dev = PL011State::new();
-    dev.prop_set_chr("chardev", &chr);
+    if !chr.is_null() {
+        let chr = unsafe { Owned::<Chardev>::from(&*chr) };
+        dev.prop_set_chr("chardev", &chr);
+    }
     dev.sysbus_realize();
     dev.mmio_map(0, addr);
     dev.connect_irq(0, &irq);
-- 
2.43.0