From 3a142fbe34eac7d92c8b2f9507ead6e3ae164863 Mon Sep 17 00:00:00 2001
From: Mark Poliakov <mark@alnyan.me>
Date: Thu, 7 Oct 2021 16:35:07 +0300
Subject: [PATCH] feat: pl031 tick

---
 kernel/src/arch/aarch64/mach_qemu/mod.rs |  6 ++
 kernel/src/dev/mod.rs                    |  5 +-
 kernel/src/dev/rtc/mod.rs                | 10 +++
 kernel/src/dev/rtc/pl031.rs              | 93 ++++++++++++++++++++++++
 4 files changed, 112 insertions(+), 2 deletions(-)
 create mode 100644 kernel/src/dev/rtc/mod.rs
 create mode 100644 kernel/src/dev/rtc/pl031.rs

diff --git a/kernel/src/arch/aarch64/mach_qemu/mod.rs b/kernel/src/arch/aarch64/mach_qemu/mod.rs
index d1dcedc..244f216 100644
--- a/kernel/src/arch/aarch64/mach_qemu/mod.rs
+++ b/kernel/src/arch/aarch64/mach_qemu/mod.rs
@@ -7,6 +7,7 @@ use crate::arch::aarch64::{
 use crate::dev::timer::TimestampSource;
 use crate::dev::{
     irq::{IntController, IntSource},
+    rtc::pl031::Pl031,
     serial::{pl011::Pl011, SerialDevice},
     Device,
 };
@@ -15,6 +16,7 @@ use error::Errno;
 pub use gic::IrqNumber;
 
 const UART0_BASE: usize = 0x09000000;
+const RTC_BASE: usize = 0x09010000;
 const GICD_BASE: usize = 0x08000000;
 const GICC_BASE: usize = 0x08010000;
 
@@ -25,6 +27,9 @@ pub fn init_board() -> Result<(), Errno> {
 
         UART0.enable()?;
         UART0.init_irqs()?;
+
+        RTC.enable()?;
+        RTC.init_irqs()?;
     }
     Ok(())
 }
@@ -48,5 +53,6 @@ pub fn intc() -> &'static impl IntController<IrqNumber = IrqNumber> {
 }
 
 static UART0: Pl011 = unsafe { Pl011::new(UART0_BASE, IrqNumber::new(33)) };
+static RTC: Pl031 = unsafe { Pl031::new(RTC_BASE, IrqNumber::new(34)) };
 static GIC: Gic = unsafe { Gic::new(GICD_BASE, GICC_BASE) };
 static LOCAL_TIMER: GenericTimer = GenericTimer {};
diff --git a/kernel/src/dev/mod.rs b/kernel/src/dev/mod.rs
index 583f438..1a03c41 100644
--- a/kernel/src/dev/mod.rs
+++ b/kernel/src/dev/mod.rs
@@ -3,10 +3,11 @@
 use error::Errno;
 
 // Device classes
-pub mod serial;
-pub mod timer;
 pub mod gpio;
 pub mod irq;
+pub mod rtc;
+pub mod serial;
+pub mod timer;
 
 /// Generic device trait
 pub trait Device {
diff --git a/kernel/src/dev/rtc/mod.rs b/kernel/src/dev/rtc/mod.rs
new file mode 100644
index 0000000..f38fb8e
--- /dev/null
+++ b/kernel/src/dev/rtc/mod.rs
@@ -0,0 +1,10 @@
+//! Interfaces and drivers for real-time clock devices
+
+use crate::dev::Device;
+
+pub mod pl031;
+
+// TODO define what RTC devices can do
+//      alarms? read real time?
+/// Interface for generic RTC device
+pub trait RtcDevice: Device {}
diff --git a/kernel/src/dev/rtc/pl031.rs b/kernel/src/dev/rtc/pl031.rs
new file mode 100644
index 0000000..bc4136c
--- /dev/null
+++ b/kernel/src/dev/rtc/pl031.rs
@@ -0,0 +1,93 @@
+//! PL031 - ARM PrimeCell real-time clock implementation
+use crate::dev::{Device, rtc::RtcDevice, irq::{IntController, IntSource}};
+use crate::arch::{MemoryIo, machine::{self, IrqNumber}};
+use crate::sync::IrqSafeNullLock;
+use error::Errno;
+use tock_registers::{
+    interfaces::{Readable, Writeable, ReadWriteable},
+    register_bitfields, register_structs,
+    registers::{ReadOnly, ReadWrite, WriteOnly},
+};
+
+register_bitfields! {
+    u32,
+    CR [
+        RTCStart OFFSET(0) NUMBITS(1) []
+    ],
+    IMSC [
+        RTCIMSC OFFSET(0) NUMBITS(1) []
+    ],
+    ICR [
+        RTCICR OFFSET(0) NUMBITS(1) []
+    ]
+}
+
+register_structs! {
+    #[allow(non_snake_case)]
+    Regs {
+        (0x00 => DR: ReadOnly<u32>),
+        (0x04 => MR: ReadWrite<u32>),
+        (0x08 => LR: ReadWrite<u32>),
+        (0x0C => CR: ReadWrite<u32, CR::Register>),
+        (0x10 => IMSC: ReadWrite<u32, IMSC::Register>),
+        (0x14 => RIS: ReadOnly<u32>),
+        (0x18 => MIS: ReadOnly<u32>),
+        (0x1C => ICR: WriteOnly<u32, ICR::Register>),
+        (0x20 => @END),
+    }
+}
+
+/// Device struct for PL031
+pub struct Pl031 {
+    regs: IrqSafeNullLock<MemoryIo<Regs>>,
+    irq: IrqNumber
+}
+
+impl RtcDevice for Pl031 {
+}
+
+impl IntSource for Pl031 {
+    fn handle_irq(&self) -> Result<(), Errno> {
+        let regs = self.regs.lock();
+        regs.ICR.write(ICR::RTCICR::SET);
+        let data = regs.DR.get();
+        regs.MR.set(data + 1);
+        Ok(())
+    }
+
+    fn init_irqs(&'static self) -> Result<(), Errno> {
+        machine::intc().register_handler(self.irq, self)?;
+        self.regs.lock().IMSC.modify(IMSC::RTCIMSC::SET);
+        machine::intc().enable_irq(self.irq)?;
+
+        Ok(())
+    }
+}
+
+impl Device for Pl031 {
+    fn name(&self) -> &'static str {
+        "PL031 RTC"
+    }
+
+    unsafe fn enable(&self) -> Result<(), Errno> {
+        let regs = self.regs.lock();
+        regs.CR.modify(CR::RTCStart::CLEAR);
+        regs.MR.set(regs.DR.get() + 1);
+        regs.CR.modify(CR::RTCStart::SET);
+        Ok(())
+    }
+}
+
+impl Pl031 {
+    /// Constructs an instance of PL031 device.
+    ///
+    /// # Safety
+    ///
+    /// Does not perform `base` validation.
+    pub const unsafe fn new(base: usize, irq: IrqNumber) -> Self {
+        Self {
+            regs: IrqSafeNullLock::new(MemoryIo::new(base)),
+            irq
+        }
+    }
+}