drtio: add FIFO space request count debug API

artiq/coredevice/drtio_dbg.py

@@ -20,3 +20,7 @@ def drtio_get_fifo_space(channel: TInt32) -> TNone:
 @syscall(flags={"nounwind", "nowrite"})
 def drtio_get_packet_counts() -> TTuple([TInt32, TInt32]):
     raise NotImplementedError("syscall not simulated")
+
+@syscall(flags={"nounwind", "nowrite"})
+def drtio_get_fifo_space_req_count() -> TInt32:
+    raise NotImplementedError("syscall not simulated")

artiq/firmware/libksupport/api.rs

@@ -110,6 +110,7 @@ static mut API: &'static [(&'static str, *const ())] = &[
     api!(drtio_reset_channel_state = ::rtio::drtio_dbg::reset_channel_state),
     api!(drtio_get_fifo_space = ::rtio::drtio_dbg::get_fifo_space),
     api!(drtio_get_packet_counts = ::rtio::drtio_dbg::get_packet_counts),
+    api!(drtio_get_fifo_space_req_count = ::rtio::drtio_dbg::get_fifo_space_req_count),
 
     api!(i2c_start = ::i2c_start),
     api!(i2c_stop = ::i2c_stop),

artiq/firmware/libksupport/rtio.rs

@@ -215,4 +215,10 @@ pub mod drtio_dbg {
         recv!(&DRTIOPacketCountReply { tx_cnt, rx_cnt }
               => PacketCounts(tx_cnt as i32, rx_cnt as i32))
     }
+
+    pub extern fn get_fifo_space_req_count() -> i32 {
+        send(&DRTIOFIFOSpaceReqCountRequest);
+        recv!(&DRTIOFIFOSpaceReqCountReply { cnt }
+              => cnt as i32)
+    }
 }

artiq/firmware/runtime/kernel_proto.rs

@@ -38,6 +38,8 @@ pub enum Message<'a> {
     DRTIOGetFIFOSpaceRequest { channel: u32 },
     DRTIOPacketCountRequest,
     DRTIOPacketCountReply { tx_cnt: u32, rx_cnt: u32 },
+    DRTIOFIFOSpaceReqCountRequest,
+    DRTIOFIFOSpaceReqCountReply { cnt: u32 },
 
     RunFinished,
     RunException {

artiq/firmware/runtime/rtio_mgt.rs

@@ -227,6 +227,12 @@ pub mod drtio_dbg {
             (csr::drtio::packet_cnt_tx_read(), csr::drtio::packet_cnt_rx_read())
         }
     }
+
+    pub fn get_fifo_space_req_count() -> u32 {
+        unsafe {
+            csr::drtio::o_dbg_fifo_space_req_cnt_read()
+        }
+    }
 }
 
 #[cfg(not(has_drtio))]
@@ -238,4 +244,6 @@ pub mod drtio_dbg {
     pub fn get_fifo_space(_channel: u32) {}
 
     pub fn get_packet_counts() -> (u32, u32) { (0, 0) }
+
+    pub fn get_fifo_space_req_count() -> u32 { 0 }
 }

artiq/firmware/runtime/session.rs

@@ -401,6 +401,10 @@ fn process_kern_message(waiter: Waiter,
                 let (tx_cnt, rx_cnt) = rtio_mgt::drtio_dbg::get_packet_counts();
                 kern_send(waiter, &kern::DRTIOPacketCountReply { tx_cnt: tx_cnt, rx_cnt: rx_cnt })
             }
+            &kern::DRTIOFIFOSpaceReqCountRequest => {
+                let cnt = rtio_mgt::drtio_dbg::get_fifo_space_req_count();
+                kern_send(waiter, &kern::DRTIOFIFOSpaceReqCountReply { cnt: cnt })
+            }
 
             &kern::WatchdogSetRequest { ms } => {
                 let id = try!(session.watchdog_set.set_ms(ms)

artiq/gateware/drtio/rt_controller.py

@@ -24,6 +24,7 @@ class _CSRs(AutoCSR):
         self.o_get_fifo_space = CSR()
         self.o_dbg_fifo_space = CSRStatus(16)
         self.o_dbg_last_timestamp = CSRStatus(64)
+        self.o_dbg_fifo_space_req_cnt = CSRStatus(32)
         self.o_reset_channel_status = CSR()
         self.o_wait = CSRStatus()
         self.o_fifo_space_timeout = CSR()
@@ -207,6 +208,11 @@ class RTController(Module):
                 last_timestamps.we.eq(1)
             )
         ]
+        self.sync += \
+            If((rt_packets.write_stb & rt_packets.write_ack & rt_packets_fifo_request),
+                self.csrs.o_dbg_fifo_space_req_cnt.status.eq(
+                    self.csrs.o_dbg_fifo_space_req_cnt.status + 1)
+            )
 
     def get_csrs(self):
         return self.csrs.get_csrs()