From 6469914be1444764f59ce418b6f4d654e2b4cacd Mon Sep 17 00:00:00 2001
From: Mark Poliakov <mark@alnyan.me>
Date: Thu, 14 Aug 2025 15:17:41 +0300
Subject: [PATCH] rtc: implement google,goldfish-rtc

---
 kernel/driver/bsp/riscv/src/goldfish_rtc.rs | 70 +++++++++++++++++++++
 kernel/driver/bsp/riscv/src/lib.rs          |  1 +
 2 files changed, 71 insertions(+)
 create mode 100644 kernel/driver/bsp/riscv/src/goldfish_rtc.rs

diff --git a/kernel/driver/bsp/riscv/src/goldfish_rtc.rs b/kernel/driver/bsp/riscv/src/goldfish_rtc.rs
new file mode 100644
index 00000000..a62a3810
--- /dev/null
+++ b/kernel/driver/bsp/riscv/src/goldfish_rtc.rs
@@ -0,0 +1,70 @@
+use alloc::sync::Arc;
+use device_api::device::{Device, DeviceInitContext};
+use device_tree::driver::{device_tree_driver, Node, ProbeContext};
+use libk::{
+    error::Error,
+    fs::sysfs::{self, nodes::SysfsRtcNode},
+};
+use libk_mm::device::DeviceMemoryIo;
+use libk_util::sync::IrqSafeSpinlock;
+use tock_registers::{
+    interfaces::Readable,
+    register_structs,
+    registers::{ReadOnly, ReadWrite},
+};
+use yggdrasil_abi::time::NANOSECONDS_IN_SECOND;
+
+register_structs! {
+    #[allow(non_snake_case)]
+    Regs {
+        (0x00 => TIME_LOW: ReadOnly<u32>),
+        (0x04 => TIME_HIGH: ReadOnly<u32>),
+        (0x08 => ALARM_LOW: ReadWrite<u32>),
+        (0x0C => ALARM_HIGH: ReadWrite<u32>),
+        (0x10 => IRQ_ENABLED: ReadWrite<u32>),
+        (0x14 => CLEAR_ALARM: ReadWrite<u32>),
+        (0x18 => ALARM_STATUS: ReadOnly<u32>),
+        (0x1C => CLEAR_INTERRUPT: ReadWrite<u32>),
+        (0x20 => @END),
+    }
+}
+
+struct Rtc {
+    regs: IrqSafeSpinlock<DeviceMemoryIo<'static, Regs>>,
+}
+
+impl SysfsRtcNode for Rtc {
+    fn read(&self) -> Result<u64, Error> {
+        let regs = self.regs.lock();
+        let low = regs.TIME_LOW.get();
+        let high = regs.TIME_HIGH.get();
+        let t = ((high as u64) << 32) | (low as u64);
+        Ok(t / NANOSECONDS_IN_SECOND)
+    }
+}
+
+impl Device for Rtc {
+    unsafe fn init(self: Arc<Self>, _cx: DeviceInitContext) -> Result<(), Error> {
+        sysfs::nodes::add_rtc_node(self.clone());
+        Ok(())
+    }
+
+    fn display_name(&self) -> &str {
+        "Google Goldfish RTC"
+    }
+}
+
+device_tree_driver! {
+    compatible: ["google,goldfish-rtc"],
+    driver: {
+        fn probe(&self, node: &Arc<Node>, context: &mut ProbeContext) -> Option<Arc<dyn Device>> {
+            let base = node.map_base(context, 0)?;
+
+            let regs = unsafe { DeviceMemoryIo::map(base, Default::default()) }.ok()?;
+
+            let rtc = Arc::new(Rtc { regs: IrqSafeSpinlock::new(regs) });
+
+            Some(rtc)
+        }
+    }
+}
diff --git a/kernel/driver/bsp/riscv/src/lib.rs b/kernel/driver/bsp/riscv/src/lib.rs
index 98a7f8ec..d2fdadb6 100644
--- a/kernel/driver/bsp/riscv/src/lib.rs
+++ b/kernel/driver/bsp/riscv/src/lib.rs
@@ -3,4 +3,5 @@
 
 extern crate alloc;
 
+mod goldfish_rtc;
 mod plic;