From ddff295ae13fd218fb4a04a73dced1060578dbca Mon Sep 17 00:00:00 2001
From: Astro <astro@spaceboyz.net>
Date: Fri, 20 Nov 2020 17:12:22 +0100
Subject: [PATCH] libboard_zynq: implement eth hot-plugging

---
 Cargo.lock                       |  1 +
 libasync/src/smoltcp/mod.rs      | 20 +++++++++++++++--
 libboard_zynq/Cargo.toml         |  1 +
 libboard_zynq/src/eth/mod.rs     | 37 +++++++++++++++++++++++---------
 libboard_zynq/src/eth/phy/mod.rs |  2 +-
 5 files changed, 48 insertions(+), 13 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index 2245d2d..abe3b33 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -89,6 +89,7 @@ version = "0.0.0"
 dependencies = [
  "bit_field",
  "embedded-hal",
+ "libasync",
  "libcortex_a9",
  "libregister",
  "log",
diff --git a/libasync/src/smoltcp/mod.rs b/libasync/src/smoltcp/mod.rs
index 6390cd8..0a819c5 100644
--- a/libasync/src/smoltcp/mod.rs
+++ b/libasync/src/smoltcp/mod.rs
@@ -7,13 +7,19 @@ use smoltcp::{
     iface::EthernetInterface,
     phy::Device,
     socket::SocketSet,
-    time::Instant,
+    time::{Duration, Instant},
 };
 use crate::task;
 
 mod tcp_stream;
 pub use tcp_stream::TcpStream;
 
+pub trait LinkCheck {
+    type Link;
+    fn is_idle(&self) -> bool;
+    fn check_link_change(&mut self) -> Option<Self::Link>;
+}
+
 static mut SOCKETS: Option<Sockets> = None;
 
 pub struct Sockets {
@@ -41,14 +47,24 @@ impl Sockets {
 
     /// Block and run executor indefinitely while polling the smoltcp
     /// iface
-    pub fn run<'b, 'c, 'e, D: for<'d> Device<'d>>(
+    pub fn run<'b, 'c, 'e, D: for<'d> Device<'d> + LinkCheck>(
         iface: &mut EthernetInterface<'b, 'c, 'e, D>,
         mut get_time: impl FnMut() -> Instant,
     ) -> ! {
         task::block_on(async {
+            let mut last_link_check = Instant::from_millis(0);
+            const LINK_CHECK_INTERVAL: u64 = 500;
+
             loop {
                 let instant = get_time();
                 Self::instance().poll(iface, instant);
+
+                let dev = iface.device_mut();
+                if dev.is_idle() && instant >= last_link_check + Duration::from_millis(LINK_CHECK_INTERVAL) {
+                    dev.check_link_change();
+                    last_link_check = instant;
+                }
+
                 task::r#yield().await;
             }
         })
diff --git a/libboard_zynq/Cargo.toml b/libboard_zynq/Cargo.toml
index da2b4b7..cc738e8 100644
--- a/libboard_zynq/Cargo.toml
+++ b/libboard_zynq/Cargo.toml
@@ -21,6 +21,7 @@ void = { version = "1", default-features = false }
 log = "0.4"
 libregister = { path = "../libregister" }
 libcortex_a9 = { path = "../libcortex_a9" }
+libasync = { path = "../libasync" }
 
 [dependencies.smoltcp]
 version = "0.6"
diff --git a/libboard_zynq/src/eth/mod.rs b/libboard_zynq/src/eth/mod.rs
index fc71346..e8e56e4 100644
--- a/libboard_zynq/src/eth/mod.rs
+++ b/libboard_zynq/src/eth/mod.rs
@@ -145,6 +145,8 @@ pub struct Eth<GEM: Gem, RX, TX> {
     tx: TX,
     inner: EthInner<GEM>,
     phy: Phy,
+    /// keep track of RX path occupation to avoid needless `check_link_change()`
+    idle: bool,
 }
 
 impl Eth<Gem0, (), ()> {
@@ -314,6 +316,7 @@ impl<GEM: Gem> Eth<GEM, (), ()> {
             tx: (),
             inner,
             phy,
+            idle: true,
         }
     }
 }
@@ -325,6 +328,7 @@ impl<GEM: Gem, RX, TX> Eth<GEM, RX, TX> {
             tx: self.tx,
             inner: self.inner,
             phy: self.phy,
+            idle: self.idle,
         };
         let list_addr = new_self.rx.list_addr();
         assert!(list_addr & 0b11 == 0);
@@ -344,6 +348,7 @@ impl<GEM: Gem, RX, TX> Eth<GEM, RX, TX> {
             tx: tx::DescList::new(tx_size),
             inner: self.inner,
             phy: self.phy,
+            idle: self.idle,
         };
         let list_addr = &new_self.tx.list_addr();
         assert!(list_addr & 0b11 == 0);
@@ -395,17 +400,31 @@ impl<GEM: Gem, TX> Eth<GEM, rx::DescList, TX> {
                         regs::RxStatus::zeroed()
                             .frame_recd(true)
                     );
+                    self.idle = true;
                 }
-                _ => {}
+                _ =>
+                    self.idle = false,
             }
             result
         } else {
-            self.inner.check_link_change(&self.phy);
+            self.idle = true;
             Ok(None)
         }
     }
 }
 
+impl<GEM: Gem, TX> libasync::smoltcp::LinkCheck for &mut Eth<GEM, rx::DescList, TX> {
+    type Link = Option<phy::Link>;
+
+    fn check_link_change(&mut self) -> Option<Self::Link> {
+        self.inner.check_link_change(&self.phy)
+    }
+
+    fn is_idle(&self) -> bool {
+        self.idle
+    }
+}
+
 impl<GEM: Gem, RX> Eth<GEM, RX, tx::DescList> {
     pub fn send<'s: 'p, 'p>(&'s mut self, length: usize) -> Option<tx::PktRef<'p>> {
         self.tx.send(GEM::regs(), length)
@@ -439,10 +458,11 @@ impl<'a, GEM: Gem> smoltcp::phy::Device<'a> for &mut Eth<GEM, rx::DescList, tx::
                     regs: GEM::regs(),
                     desc_list: &mut self.tx,
                 };
+                self.idle = false;
                 Some((pktref, tx_token))
             }
             Ok(None) => {
-                self.inner.check_link_change(&self.phy);
+                self.idle = true;
                 None
             }
             Err(e) => {
@@ -602,13 +622,7 @@ impl<GEM: Gem> EthInner<GEM> {
     }
 
 
-    fn check_link_change(&mut self, phy: &Phy) {
-        // As the PHY access takes some time, exit early if there was
-        // already a link. TODO: check once per second.
-        if self.link.is_some() {
-            return
-        }
-
+    fn check_link_change(&mut self, phy: &Phy) -> Option<Option<phy::Link>> {
         let link = phy.get_link(self);
 
         // Check link state transition
@@ -640,6 +654,9 @@ impl<GEM: Gem> EthInner<GEM> {
             }
 
             self.link = link;
+            Some(link)
+        } else {
+            None
         }
     }
 }
diff --git a/libboard_zynq/src/eth/phy/mod.rs b/libboard_zynq/src/eth/phy/mod.rs
index f123b51..47f9659 100644
--- a/libboard_zynq/src/eth/phy/mod.rs
+++ b/libboard_zynq/src/eth/phy/mod.rs
@@ -7,7 +7,7 @@ pub use control::Control;
 mod pssr;
 pub use pssr::PSSR;
 
-#[derive(Clone, Debug, PartialEq)]
+#[derive(Copy, Clone, Debug, PartialEq)]
 pub struct Link {
     pub speed: LinkSpeed,
     pub duplex: LinkDuplex,