lx_emul: add PCI config space handling

Ref genodelabs/genode#4411

repos/dde_linux/src/include/lx_emul/pci_config_space.h

@@ -0,0 +1,28 @@
+/*
+ * \brief  Lx_emul support for accessing PCI(e) config space
+ * \author Josef Soentgen
+ * \date   2022-01-18
+ */
+
+/*
+ * Copyright (C) 2022 Genode Labs GmbH
+ *
+ * This file is distributed under the terms of the GNU General Public License
+ * version 2.
+ */
+
+#ifndef _LX_EMUL__PCI_CONFIG_SPACE_H_
+#define _LX_EMUL__PCI_CONFIG_SPACE_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+int lx_emul_pci_read_config(unsigned bus, unsigned devfn, unsigned reg, unsigned len, unsigned *val);
+int lx_emul_pci_write_config(unsigned bus, unsigned devfn, unsigned reg, unsigned len, unsigned val);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _LX_EMUL__PCI_CONFIG_SPACE_H_ */

repos/dde_linux/src/include/lx_kit/device.h

@@ -122,6 +122,9 @@ class Lx_kit::Device : List<Device>::Element
 		bool   irq_unmask(unsigned irq);
 		void   irq_mask(unsigned irq);
 		void   irq_ack(unsigned irq);
+
+		bool   read_config(unsigned reg, unsigned len, unsigned *val);
+		bool   write_config(unsigned reg, unsigned len, unsigned  val);
 };
 
 

repos/dde_linux/src/lib/lx_emul/pci_config_space.cc

@@ -0,0 +1,82 @@
+/*
+ * \brief  Lx_emul backend for accessing PCI(e) config space
+ * \author Josef Soentgen
+ * \date   2022-01-18
+ */
+
+/*
+ * Copyright (C) 2022 Genode Labs GmbH
+ *
+ * This file is distributed under the terms of the GNU General Public License
+ * version 2.
+ */
+
+#include <lx_kit/env.h>
+#include <lx_emul/pci_config_space.h>
+
+
+using Device_name = Genode::String<16>;
+
+template <typename T, typename... TAIL>
+static Device_name to_string(T const &arg, TAIL &&... args)
+{
+        return Device_name(arg, args...);
+}
+
+
+static Device_name assemble(unsigned bus, unsigned devfn)
+{
+	using namespace Genode;
+	return to_string("pci-",
+	                 Hex(bus,                  Hex::OMIT_PREFIX), ":",
+	                 Hex((devfn >> 3) & 0x1fu, Hex::OMIT_PREFIX), ".",
+	                 Hex(devfn & 0x7u,         Hex::OMIT_PREFIX));
+}
+
+
+int lx_emul_pci_read_config(unsigned bus, unsigned devfn,
+                            unsigned reg, unsigned len, unsigned *val)
+{
+	using namespace Lx_kit;
+	using namespace Genode;
+
+	Device_name name = assemble(bus, devfn);
+
+	bool result = false;
+	bool matched = false;
+
+	env().devices.for_each([&] (Device & d) {
+		matched = name == d.name();
+		if (matched && val)
+			result = d.read_config(reg, len, val);
+	});
+
+	if (!result && matched)
+		error("could not read config space register ", Hex(reg));
+
+	return result ? 0 : -1;
+}
+
+
+int lx_emul_pci_write_config(unsigned bus, unsigned devfn,
+                             unsigned reg, unsigned len, unsigned val)
+{
+	using namespace Lx_kit;
+	using namespace Genode;
+
+	Device_name name = assemble(bus, devfn);
+
+	bool result = false;
+	bool matched = false;
+	env().devices.for_each ([&] (Device & d) {
+		matched = name == d.name();
+		if (matched)
+			result = d.write_config(reg, len, val);
+	});
+
+	if (!result && matched)
+		error("could not write config space register ", Hex(reg),
+		      " with ", Hex(val));
+
+	return result ? 0 : -1;
+}