Add UART driver for SAMG

Author: mcbridejc

README.md

@@ -437,7 +437,7 @@ Please [discover modm's peripheral drivers for your specific device][discover].
 <td align="center">✅</td>
 <td align="center">✅</td>
 <td align="center">✅</td>
-<td align="center">○</td>
+<td align="center">✅</td>
 <td align="center">○</td>
 <td align="center">✅</td>
 <td align="center">✅</td>

examples/samg55_xplained_pro/uart/main.cpp

@@ -0,0 +1,33 @@
+/*
+ * Copyright (c) 2021, Jeff McBride
+ *
+ * This file is part of the modm project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#include <modm/board.hpp>
+#include <modm/io/iostream.hpp>
+
+using namespace modm::platform;
+using namespace modm::literals;
+
+// Create IO wrapper for the debug UART, which is connected to the built-in
+// USB debugger virtual COM port
+modm::IODeviceWrapper<Board::DebugUart, modm::IOBuffer::BlockIfFull> debugDevice;
+modm::IOStream debugStream(debugDevice);
+
+int
+main()
+{
+	Board::initialize();
+
+	uint32_t cycle = 0;
+	while (true)
+	{
+		modm::delay(1s);
+		debugStream.printf("Cycle: %lu\r\n", cycle);
+	}
+}

examples/samg55_xplained_pro/uart/project.xml

@@ -0,0 +1,9 @@
+<library>
+  <extends>modm:samg55-xplained-pro</extends>
+  <options>
+    <option name="modm:build:build.path">../../../build/samg55_xplained_pro/uart</option>
+  </options>
+  <modules>
+    <module>modm:build:scons</module>
+  </modules>
+</library>

src/modm/board/samg55_xplained_pro/board.hpp

@@ -25,8 +25,10 @@ struct SystemClock
 	// Chosen to achieve 48MHz USB clock
 	static constexpr uint32_t PllBMult = 1465;
 
-	static constexpr uint32_t Frequency = PllAMult * SlowClkFreqHz;
+	static constexpr uint32_t Frequency = PllAMult * SlowClkFreqHz; // CPU core frequency
 	static constexpr uint32_t Usb = PllBMult * SlowClkFreqHz;
+	static constexpr uint32_t Mck = Frequency; // Master clock, used by most peripherals
+
 	static bool inline
 	enable()
 	{
@@ -50,6 +52,9 @@ struct SystemClock
 
 using Led = GpioA6;
 using Button = GpioA2;
+using DebugUart = Uart7;
+using TxPin = GpioA28;
+using RxPin = GpioA27;
 
 inline void
 initialize()
@@ -60,6 +65,9 @@ initialize()
 	SystemClock::enable();
 	SysTickTimer::initialize<SystemClock>();
 
+	DebugUart::initialize<SystemClock, 115200>();
+	DebugUart::connect<TxPin::Tx, RxPin::Rx>();
+
 	Led::setOutput(modm::Gpio::Low);
 
 	Button::setInput();

src/modm/board/samg55_xplained_pro/module.lb

@@ -18,7 +18,13 @@ def prepare(module, options):
     if not options[":target"].partname == "samg55j19a-au":
         return False
 
-    module.depends(":platform:clockgen", ":platform:gpio", ":platform:core", ":platform:usb");
+    module.depends(
+        ":platform:clockgen",
+        ":platform:uart:7",
+        ":platform:gpio",
+        ":platform:core",
+        ":platform:usb",
+        ":io")
     return True
 
 def build(env):

src/modm/platform/uart/samg/module.lb

@@ -0,0 +1,83 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+#
+# Copyright (c) 2021, Jeff McBride
+#
+# This file is part of the modm project.
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+# -----------------------------------------------------------------------------
+
+props = {}
+
+class Instance(Module):
+    def __init__(self, driver, instance):
+        self.driver = driver
+        self.instance = int(instance)
+
+    def init(self, module):
+        module.name = str(self.instance)
+        module.description = "Instance {}".format(self.instance)
+
+    def prepare(self, module, options):
+        module.depends(":platform:uart")
+
+        module.add_option(
+            NumericOption(
+                name="buffer.tx",
+                description="Size of transmit buffer",
+                minimum=1, maximum=2 ** 16 - 2,
+                default=64))
+        module.add_option(
+            NumericOption(
+                name="buffer.rx",
+                description="Size of receive buffer",
+                minimum=1, maximum=2 ** 16 - 2,
+                default=64))
+
+        return True
+
+    def build(self, env):
+        device = env[":target"].identifier
+        global props
+        props["id"] = self.instance
+
+        env.substitutions = props
+        env.outbasepath = "modm/src/modm/platform/uart"
+
+        env.template("uart.hpp.in", "uart_{}.hpp".format(self.instance))
+        env.template("uart.cpp.in", "uart_{}.cpp".format(self.instance))
+
+
+def init(module):
+    module.name = ":platform:uart"
+    module.description = "Universal Synchronous Asynchronous Receiver Transmitter (UART)"
+
+def prepare(module, options):
+    device = options[":target"]
+    if not (device.has_driver("usart:samg*")):
+        return False
+
+    module.depends(
+        ":architecture:uart",
+        ":math:algorithm",
+        ":cmsis:device",
+        ":platform:gpio",
+        ":platform:clockgen")
+
+    global props
+    drivers = options[":target"].get_all_drivers("usart")
+    for driver in drivers:
+        for instance in driver["instance"]:
+            module.add_submodule(Instance(driver, instance))
+
+    props["target"] = device.identifier
+    return True
+
+def build(env):
+    global props
+    env.substitutions = props
+    env.outbasepath = "modm/src/modm/platform/uart"
+    env.copy("uart_base.hpp")

src/modm/platform/uart/samg/uart.cpp.in

@@ -0,0 +1,127 @@
+/*
+ * Copyright (c) 2021, Jeff McBride
+ *
+ * This file is part of the modm project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+// ----------------------------------------------------------------------------
+
+#include "uart_{{ id }}.hpp"
+
+#include <modm/architecture/driver/atomic/queue.hpp>
+
+namespace
+{
+	static modm::atomic::Queue<uint8_t, {{ options["buffer.rx"] }}> rxBuffer;
+	static modm::atomic::Queue<uint8_t, {{ options["buffer.tx"] }}> txBuffer;
+}
+
+MODM_ISR(FLEXCOM{{ id }})
+{
+	using namespace modm::platform;
+	if(Uart{{ id }}::isReceiveReady()) {
+		uint8_t data = (uint8_t)USART{{ id }}->US_RHR;
+		Uart{{ id }}::read(data);
+		rxBuffer.push(data);
+	}
+
+	if(Uart{{ id }}::isTransmitReady()) {
+		if(txBuffer.isEmpty()) {
+			USART{{ id }}->US_IDR = US_IDR_TXRDY;
+		} else {
+			USART{{ id }}->US_THR = txBuffer.get();
+			txBuffer.pop();
+		}
+	}
+}
+
+namespace modm::platform
+{
+
+bool
+Uart{{ id }}::read(uint8_t &dataOut) {
+	if(rxBuffer.isEmpty()) {
+		return false;
+	} else {
+		dataOut = rxBuffer.get();
+		rxBuffer.pop();
+		return true;
+	}
+}
+
+std::size_t
+Uart{{ id }}::read(uint8_t *data, std::size_t length) {
+	uint32_t i = 0;
+	for(; i < length; i++) {
+		if(rxBuffer.isEmpty()) {
+			return i;
+		} else {
+			data[i] = rxBuffer.get();
+			rxBuffer.pop();
+		}
+	}
+	return i;
+}
+
+bool
+Uart{{ id }}::write(uint8_t data)
+{
+	if(txBuffer.isEmpty() && isTransmitReady()) {
+		USART{{ id }}->US_THR = data;
+	} else {
+		if(!txBuffer.push(data)) {
+			return false;
+		}
+		// Enable tx interrupt
+		USART{{ id }}->US_IER = US_IER_TXRDY;
+	}
+	return true;
+}
+
+std::size_t
+Uart{{ id }}::write(const uint8_t *data, std::size_t length)
+{
+	uint32_t i = 0;
+	for(; i < length; i++) {
+		if(!write(data[i])) {
+			return i;
+		}
+	}
+	return i;
+}
+
+bool
+Uart{{ id }}::isWriteFinished()
+{
+	return txBuffer.isEmpty() && isTransmitReady();
+}
+
+void
+Uart{{ id }}::flushWriteBuffer()
+{
+	while(!isWriteFinished());
+}
+
+void
+Uart{{ id }}::setParity(Parity parity)
+{
+	USART{{ id }}->US_MR = (USART{{ id }}->US_MR & ~US_MR_PAR_Msk) | (uint32_t)parity;
+}
+
+void
+Uart{{ id }}::setWordLength(WordLength length)
+{
+	if(length == WordLength::Bit9) {
+		USART{{ id }}->US_MR |= US_MR_MODE9;
+	} else {
+		USART{{ id }}->US_MR &= ~US_MR_MODE9;
+		USART{{ id }}->US_MR =
+			(USART{{ id }}->US_MR & ~US_MR_CHRL_Msk)
+				| US_MR_CHRL((uint32_t)length);
+	}
+}
+
+} // namespace modm::platform