[PATCH 3/7] rust: pl011: always use reset() method on registers

[Paolo Bonzini]

For CR, the ugly-ish "0.into()" idiom is already hidden within the
Default trait.  Do not repeat it.

For FR, standardize on reset() being equivalent to "*self = Self::default()"
and let reset_fifo toggle only the bits that are related to FIFOs.  This
commit also reproduces C commit 02b1f7f6192 ("hw/char/pl011: Split RX/TX
path of pl011_reset_fifo()", 2024-09-13).

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 rust/hw/char/pl011/src/device.rs | 23 ++++++++++++++++-------
 rust/hw/char/pl011/src/lib.rs    | 13 +++++--------
 2 files changed, 21 insertions(+), 15 deletions(-)

diff --git a/rust/hw/char/pl011/src/device.rs b/rust/hw/char/pl011/src/device.rs
index c6a8dbe1af4..eb15e9d5788 100644
--- a/rust/hw/char/pl011/src/device.rs
+++ b/rust/hw/char/pl011/src/device.rs
@@ -267,7 +267,7 @@ pub fn write(&mut self, offset: hwaddr, value: u64) {
                 self.update();
             }
             Ok(RSR) => {
-                self.receive_status_error_clear = 0.into();
+                self.receive_status_error_clear.reset();
             }
             Ok(FR) => {
                 // flag writes are ignored
@@ -288,7 +288,8 @@ pub fn write(&mut self, offset: hwaddr, value: u64) {
                 if bool::from(self.line_control.fifos_enabled())
                     ^ bool::from(new_val.fifos_enabled())
                 {
-                    self.reset_fifo();
+                    self.reset_rx_fifo();
+                    self.reset_tx_fifo();
                 }
                 if self.line_control.send_break() ^ new_val.send_break() {
                     let mut break_enable: c_int = new_val.send_break().into();
@@ -447,16 +448,24 @@ pub fn reset(&mut self) {
         self.read_trigger = 1;
         self.ifl = 0x12;
         self.control.reset();
-        self.flags = 0.into();
-        self.reset_fifo();
+        self.flags.reset();
+        self.reset_rx_fifo();
+        self.reset_tx_fifo();
     }
 
-    pub fn reset_fifo(&mut self) {
+    pub fn reset_rx_fifo(&mut self) {
         self.read_count = 0;
         self.read_pos = 0;
 
-        /* Reset FIFO flags */
-        self.flags.reset();
+        // Reset FIFO flags
+        self.flags.set_receive_fifo_full(false);
+        self.flags.set_receive_fifo_empty(true);
+    }
+
+    pub fn reset_tx_fifo(&mut self) {
+        // Reset FIFO flags
+        self.flags.set_transmit_fifo_full(false);
+        self.flags.set_transmit_fifo_empty(true);
     }
 
     pub fn can_receive(&self) -> bool {
diff --git a/rust/hw/char/pl011/src/lib.rs b/rust/hw/char/pl011/src/lib.rs
index d5089f78854..e3eacb0e6b9 100644
--- a/rust/hw/char/pl011/src/lib.rs
+++ b/rust/hw/char/pl011/src/lib.rs
@@ -230,7 +230,7 @@ pub struct ReceiveStatusErrorClear {
     impl ReceiveStatusErrorClear {
         pub fn reset(&mut self) {
             // All the bits are cleared to 0 on reset.
-            *self = 0.into();
+            *self = Self::default();
         }
     }
 
@@ -297,19 +297,16 @@ pub struct Flags {
 
     impl Flags {
         pub fn reset(&mut self) {
-            // After reset TXFF, RXFF, and BUSY are 0, and TXFE and RXFE are 1
-            self.set_receive_fifo_full(false);
-            self.set_transmit_fifo_full(false);
-            self.set_busy(false);
-            self.set_receive_fifo_empty(true);
-            self.set_transmit_fifo_empty(true);
+            *self = Self::default();
         }
     }
 
     impl Default for Flags {
         fn default() -> Self {
             let mut ret: Self = 0.into();
-            ret.reset();
+            // After reset TXFF, RXFF, and BUSY are 0, and TXFE and RXFE are 1
+            ret.set_receive_fifo_empty(true);
+            ret.set_transmit_fifo_empty(true);
             ret
         }
     }
-- 
2.47.1