From b03059b933b5677327c6f4cb7fa113b637bdfa2b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Josef=20S=C3=B6ntgen?= <josef.soentgen@genode-labs.com>
Date: Thu, 4 Aug 2022 11:12:04 +0200
Subject: [PATCH] dde_linux: allow GPIO state access

To complement the GPIO support allow for setting and reading input
pins. So far this is needed by drivers that attempt to perform I2C
bit-banging via GPIO pins.

Fixes #4624.
---
 repos/dde_linux/src/include/lx_emul/pin.h |  7 +++++
 repos/dde_linux/src/lib/lx_emul/pin.cc    | 35 +++++++++++++++++++++++
 2 files changed, 42 insertions(+)

diff --git a/repos/dde_linux/src/include/lx_emul/pin.h b/repos/dde_linux/src/include/lx_emul/pin.h
index 74bb5dbb43..f5d554f66e 100644
--- a/repos/dde_linux/src/include/lx_emul/pin.h
+++ b/repos/dde_linux/src/include/lx_emul/pin.h
@@ -25,6 +25,13 @@ extern "C" {
  */
 void lx_emul_pin_control(char const *pin_name, bool enabled);
 
+/**
+ * Get input state of GPIO pin
+ *
+ * \pin_name  GPIO name used as label for corresponding 'Pin_state' session
+ */
+int lx_emul_pin_sense(char const *pin_name);
+
 /**
  * Request interrupt backed by an IRQ session
  */
diff --git a/repos/dde_linux/src/lib/lx_emul/pin.cc b/repos/dde_linux/src/lib/lx_emul/pin.cc
index 7fb683dbfd..2a78f67975 100644
--- a/repos/dde_linux/src/lib/lx_emul/pin.cc
+++ b/repos/dde_linux/src/lib/lx_emul/pin.cc
@@ -14,6 +14,7 @@
 /* Genode includes */
 #include <base/registry.h>
 #include <pin_control_session/connection.h>
+#include <pin_state_session/connection.h>
 #include <irq_session/connection.h>
 
 #include <lx_emul/pin.h>
@@ -75,10 +76,13 @@ namespace {
 		Name const name;
 
 		Constructible<Pin_control::Connection> _control { };
+		Constructible<Pin_state::Connection>   _state   { };
 		Constructible<Irq_connection>          _irq     { };
 
 		Io_signal_handler<Pin> _irq_handler { _env.ep(), *this, &Pin::_handle_irq };
 
+		enum class Direction { IN, OUT } _direction { Direction::IN };
+
 		void _handle_irq()
 		{
 			_pin_irq_handler.handle_pin_irq(_irq_info);
@@ -100,6 +104,25 @@ namespace {
 				_control.construct(_env, name.string());
 
 			_control->state(enabled);
+			_direction = Direction::OUT;
+		}
+
+		bool sense()
+		{
+			if (_irq.constructed()) {
+				error("attempt to drive interrupt pin ", name, " as input");
+				return false;
+			}
+
+			if (_control.constructed() && (_direction == Direction::OUT)) {
+				_control->yield();
+				_direction = Direction::IN;
+			}
+
+			if (!_state.constructed())
+				_state.construct(_env, name.string());
+
+			return _state->state();
 		}
 
 		void associate_with_gic_and_unmask_irq(Irq_info irq_info)
@@ -200,6 +223,18 @@ extern "C" void lx_emul_pin_control(char const *pin_name, bool enabled)
 }
 
 
+extern "C" void lx_emul_backtrace(void);
+
+
+extern "C" int lx_emul_pin_sense(char const *pin_name)
+{
+	bool result = false;
+	pins().with_pin(pin_name, [&] (Pin &pin) {
+		result = pin.sense(); });
+	return result;
+}
+
+
 extern "C" void lx_emul_pin_irq_unmask(unsigned gic_irq, unsigned pin_irq,
                                        char const *pin_name)
 {