[opentitanlib] Add gpio implementation for ftdi transport

Signed-off-by: Douglas Reis <[email protected]>

sw/host/opentitanlib/BUILD

@@ -183,6 +183,7 @@ rust_library(
         "src/transport/dediprog/spi.rs",
         "src/transport/errors.rs",
         "src/transport/ftdi/chip.rs",
+        "src/transport/ftdi/gpio.rs",
         "src/transport/ftdi/mod.rs",
         "src/transport/hyperdebug/c2d2.rs",
         "src/transport/hyperdebug/dfu.rs",

sw/host/opentitanlib/src/transport/ftdi/gpio.rs

@@ -0,0 +1,83 @@
+// Copyright lowRISC contributors (OpenTitan project).
+// Licensed under the Apache License, Version 2.0, see LICENSE for details.
+// SPDX-License-Identifier: Apache-2.0
+
+use anyhow::Result;
+use std::cell::RefCell;
+use std::collections::HashMap;
+use std::rc::Rc;
+
+use embedded_hal::digital::OutputPin;
+use ftdi_embedded_hal as ftdi_hal;
+
+use crate::io::gpio::{GpioError, GpioPin, PinMode, PullMode};
+use crate::transport::ftdi::Chip;
+
+pub struct Pin {
+    pin: Rc<RefCell<ftdi_hal::OutputPin<ftdi::Device>>>,
+    pinname: String,
+}
+
+impl Pin {
+    pub fn open<C: Chip>(
+        ftdi_interfaces: &HashMap<ftdi::Interface, ftdi_hal::FtHal<ftdi::Device>>,
+        pinname: String,
+    ) -> Result<Self> {
+        let pinname = pinname.to_lowercase();
+        let (interface, pin) = pinname.split_at(1);
+        let interface = match interface {
+            "a" => ftdi::Interface::A,
+            "b" => ftdi::Interface::B,
+            "c" => ftdi::Interface::C,
+            "d" => ftdi::Interface::D,
+            &_ => panic!("{}", pinname.clone()),
+        };
+
+        let hal = ftdi_interfaces
+            .get(&interface)
+            .ok_or_else(|| GpioError::InvalidPinName(pinname.clone()))?;
+        let pin = match pin {
+            "dbus0" => hal.ad0(),
+            "dbus1" => hal.ad1(),
+            "dbus2" => hal.ad2(),
+            "dbus3" => hal.ad3(),
+            "dbus4" => hal.ad4(),
+            "dbus5" => hal.ad5(),
+            "dbus6" => hal.ad6(),
+            "dbus7" => hal.ad7(),
+            _ => return Err(GpioError::InvalidPinName(pinname).into()),
+        }?;
+
+        Ok(Self {
+            pin: Rc::new(RefCell::new(pin)),
+            pinname,
+        })
+    }
+}
+
+impl GpioPin for Pin {
+    fn read(&self) -> Result<bool> {
+        Ok(false)
+    }
+
+    fn write(&self, value: bool) -> Result<()> {
+        if value {
+            self.pin.borrow_mut().set_high()?;
+        } else {
+            self.pin.borrow_mut().set_low()?;
+        }
+        Ok(())
+    }
+
+    fn set_mode(&self, _mode: PinMode) -> Result<()> {
+        Ok(())
+    }
+
+    fn set_pull_mode(&self, _mode: PullMode) -> Result<()> {
+        Ok(())
+    }
+
+    fn get_internal_pin_name(&self) -> Option<&str> {
+        Some(&self.pinname)
+    }
+}

sw/host/opentitanlib/src/transport/ftdi/mod.rs

@@ -25,6 +25,7 @@ use chip::Chip;
 use ftdi_embedded_hal as ftdi_hal;
 
 pub mod chip;
+pub mod gpio;
 
 #[derive(Default)]
 struct Inner {
@@ -101,7 +102,17 @@ impl<C: Chip> Transport for Ftdi<C> {
     }
 
     fn gpio_pin(&self, pinname: &str) -> Result<Rc<dyn GpioPin>> {
-        Err(TransportError::UnsupportedOperation.into())
+        let mut inner = self.inner.borrow_mut();
+        Ok(match inner.gpio.entry(pinname.to_string()) {
+            Entry::Vacant(v) => {
+                let u = v.insert(Rc::new(gpio::Pin::open::<C>(
+                    &self.ftdi_interfaces,
+                    pinname.to_string(),
+                )?));
+                Rc::clone(u)
+            }
+            Entry::Occupied(o) => Rc::clone(o.get()),
+        })
     }
 
     fn spi(&self, _instance: &str) -> Result<Rc<dyn Target>> {