From 07715a71514fbc61b0447dc6c8c30ba385b79fef Mon Sep 17 00:00:00 2001
From: "Sascha Schade (strongly-typed)" <stronglytyp3d@gmail.com>
Date: Tue, 27 Nov 2018 18:27:43 +0100
Subject: [PATCH] [arch] Add I2C multiplexer as I2C device

---
 .../architecture/interface/gpio_expander.hpp  |   2 +-
 .../interface/i2c_multiplexer.hpp             | 117 ++++++++++++++++++
 src/modm/architecture/module.lb               |  15 +++
 3 files changed, 133 insertions(+), 1 deletion(-)
 create mode 100644 src/modm/architecture/interface/i2c_multiplexer.hpp

diff --git a/src/modm/architecture/interface/gpio_expander.hpp b/src/modm/architecture/interface/gpio_expander.hpp
index 8d0a36c2b7..cad784cbf7 100644
--- a/src/modm/architecture/interface/gpio_expander.hpp
+++ b/src/modm/architecture/interface/gpio_expander.hpp
@@ -141,7 +141,7 @@ class GpioExpander
 	/// Returns the input bits: 0 for low, 1 for high
 	Pins
 	getInputs() const;
-#endif
+#endif // __DOXYGEN__
 };
 
 /**
diff --git a/src/modm/architecture/interface/i2c_multiplexer.hpp b/src/modm/architecture/interface/i2c_multiplexer.hpp
new file mode 100644
index 0000000000..52f9cc884c
--- /dev/null
+++ b/src/modm/architecture/interface/i2c_multiplexer.hpp
@@ -0,0 +1,117 @@
+/*
+ * Copyright (c) 2018, Sascha Schade
+ *
+ * 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/.
+ */
+// ----------------------------------------------------------------------------
+
+#ifndef MODM_I2C_MULTIPLEXER_HPP
+#define MODM_I2C_MULTIPLEXER_HPP
+
+#include <modm/processing/resumable.hpp>
+
+namespace modm
+{
+
+/**
+ * Interface of an I2C Multiplexer.
+ *
+ * All I2C multiplexer driver should implement this interface.
+ * @ingroup modm_architecture_i2c_multiplexer
+ */
+template <
+	auto &multiplexer,
+	typename std::remove_reference_t<decltype(multiplexer)>::Channel channel >
+	class I2cMultiplexerChannel : public modm::I2cMaster
+{
+public:
+	static constexpr auto &i2cMultiplexer = multiplexer;
+
+public:
+	static bool
+	start(I2cTransaction *transaction, ConfigurationHandler handler = nullptr);
+};
+
+/// @ingroup modm_architecture_i2c_multiplexer
+struct i2cMultiplexer
+{
+public:
+	enum class
+	Channel : uint8_t
+	{
+		Ch0 = 0,
+		Ch1 = 1,
+		Ch2 = 2,
+		Ch3 = 3,
+		Ch4 = 4,
+		Ch5 = 5,
+		Ch6 = 6,
+		Ch7 = 7
+	};
+}; // struct i2cMultiplexer
+
+
+/// @ingroup modm_architecture_i2c_multiplexer
+template < class I2cMaster, class I2cMultiplexerDevice >
+class I2cMultiplexer : public i2cMultiplexer, public modm::I2c
+{
+public:
+	/// Constructor, sets address to default of 0x70
+	I2cMultiplexer();
+
+	static bool
+	start(I2cTransaction *transaction, ConfigurationHandler handler = nullptr)
+	{
+		return I2cMaster::start(transaction, handler);
+	}
+
+public:
+	/// Alias-templates for simpler use of the Channels
+	/// @{
+	template < auto &object >
+	using Ch0 = I2cMultiplexerChannel< object, Channel::Ch0 >;
+	template < auto &object >
+	using Ch1 = I2cMultiplexerChannel< object, Channel::Ch1 >;
+	template < auto &object >
+	using Ch2 = I2cMultiplexerChannel< object, Channel::Ch2 >;
+	template < auto &object >
+	using Ch3 = I2cMultiplexerChannel< object, Channel::Ch3 >;
+	template < auto &object >
+	using Ch4 = I2cMultiplexerChannel< object, Channel::Ch4 >;
+	template < auto &object >
+	using Ch5 = I2cMultiplexerChannel< object, Channel::Ch5 >;
+	template < auto &object >
+	using Ch6 = I2cMultiplexerChannel< object, Channel::Ch6 >;
+	template < auto &object >
+	using Ch7 = I2cMultiplexerChannel< object, Channel::Ch7 >;
+	/// @}
+
+	I2cMultiplexerDevice multiplexerDevice;
+};
+
+} // modm namespace
+
+template < class I2cMaster, class I2cMultiplexerDevice  >
+modm::I2cMultiplexer<I2cMaster, I2cMultiplexerDevice >::I2cMultiplexer()
+{
+}
+
+template <
+	auto &multiplexer,
+	typename std::remove_reference_t<decltype(multiplexer)>::Channel channel >
+bool
+modm::I2cMultiplexerChannel<multiplexer, channel>::start(modm::I2cTransaction *transaction, ConfigurationHandler handler)
+{
+	// If call to multiplexer failed, return without doing the actual transaction
+	if (RF_CALL_BLOCKING(multiplexer.multiplexerDevice.setActiveChannel(static_cast<uint8_t>(channel))) == false) {
+		return false;
+	}
+
+	return multiplexer.start(transaction, handler);
+}
+
+#endif // MODM_I2C_MULTIPLEXER_HPP
diff --git a/src/modm/architecture/module.lb b/src/modm/architecture/module.lb
index a9faafe426..102564ea23 100644
--- a/src/modm/architecture/module.lb
+++ b/src/modm/architecture/module.lb
@@ -206,6 +206,20 @@ class I2cDevice(Module):
         env.copy("interface/i2c_device.hpp")
 # -----------------------------------------------------------------------------
 
+class I2cMultiplexer(Module):
+    def init(self, module):
+        module.name = "i2c.multiplexer"
+        module.description = "I²C Multiplexer"
+
+    def prepare(self, module, options):
+        module.depends(":architecture:i2c", ":architecture:register", ":processing:resumable", ":math:utils")
+        return True
+
+    def build(self, env):
+        env.outbasepath = "modm/src/modm/architecture"
+        env.copy("interface/i2c_multiplexer.hpp")
+# -----------------------------------------------------------------------------
+
 class Interrupt(Module):
     def init(self, module):
         module.name = "interrupt"
@@ -342,6 +356,7 @@ def prepare(module, options):
     module.add_submodule(Heap())
     module.add_submodule(I2c())
     module.add_submodule(I2cDevice())
+    module.add_submodule(I2cMultiplexer())
     module.add_submodule(Interrupt())
     module.add_submodule(Memory())
     module.add_submodule(OneWire())