kapi: add power management support to drivers

1 files changed, 93 insertions, 0 deletions

diff --git a/kernel/kapi/devices/power.cpp b/kernel/kapi/devices/power.cpp
new file mode 100644
index 00000000..3bc66848
--- /dev/null
+++ b/kernel/kapi/devices/power.cpp
@@ -0,0 +1,93 @@
+#include <kapi/devices/power.hpp>
+
+#include <kapi/devices.hpp>
+
+#include <kstd/memory.hpp>
+#include <kstd/print.hpp>
+#include <kstd/result.hpp>
+#include <kstd/vector.hpp>
+
+#include <ranges>
+
+namespace kapi::devices
+{
+
+  namespace
+  {
+    auto resume_subtree(device & node) -> void;
+
+    // NOLINTNEXTLINE(misc-no-recursion)
+    auto suspend_subtree(device & node) -> kstd::result<void>
+    {
+      auto suspended_children = kstd::vector<kstd::shared_ptr<device>>{};
+
+      if (auto as_bus = node.facet<bus>())
+      {
+        for (auto const & child : as_bus->children())
+        {
+          auto result = suspend_subtree(*child);
+          if (!result)
+          {
+            for (auto const & already_suspended : std::views::reverse(suspended_children))
+            {
+              resume_subtree(*already_suspended);
+            }
+
+            return result;
+          }
+
+          suspended_children.push_back(child);
+        }
+      }
+
+      if (auto driver = node.bound_driver())
+      {
+        auto result = driver->suspend(node);
+        if (!result)
+        {
+          for (auto const & already_suspended : std::views::reverse(suspended_children))
+          {
+            resume_subtree(*already_suspended);
+          }
+
+          return result;
+        }
+      }
+
+      return kstd::success();
+    }
+
+    // NOLINTNEXTLINE(misc-no-recursion)
+    auto resume_subtree(device & node) -> void
+    {
+      if (auto driver = node.bound_driver())
+      {
+        auto result = driver->resume(node);
+        if (!result)
+        {
+          kstd::println(kstd::print_sink::stderr, "[OS:PM] failed to resume device '{}': {}", node.name(),
+                        result.error().message());
+        }
+      }
+
+      if (auto as_bus = node.facet<bus>())
+      {
+        for (auto const & child : as_bus->children())
+        {
+          resume_subtree(*child);
+        }
+      }
+    }
+  }  // namespace
+
+  auto suspend_tree(bus & root) -> kstd::result<void>
+  {
+    return suspend_subtree(root);
+  }
+
+  auto resume_tree(bus & root) -> void
+  {
+    resume_subtree(root);
+  }
+
+}  // namespace kapi::devices
\ No newline at end of file