feat: add PS/2 keyboard interrupt driver

[GloriousAlpaca]

This feature adds support for the PS2 legacy keyboard in Qemu x86_64.
Currently it does:

1. A minimized hardware initialization (e.g. flush the output buffer) to use the keyboard, according to the standards for the Intel 8042 chip: Link to OSDev
2. Install an interrupt handler, which is done in the install_handlers function in interrupt.rs, as it is a hardware interrupt but does not belong in the pci interrupt handlers list (legacy device).
3. Add a systemcall to pop the last scancode out of the keyboard input ringbuffer (which currently has a length of 256). The Ringbuffer also uses Atomics, to prevent races and deadlocks.
   The systemcall returns 0 if the keyboard feature is disabled.

I have only tested this feature with C programs on a Mac using Qemu.

[github-actions]

Benchmark Results

Details

Benchmark	Current: 153302f	Previous: 2e23902	Performance Ratio
startup_benchmark Build Time	81.54 s	80.34 s	1.01 ❗
startup_benchmark File Size	0.80 MB	0.80 MB	1.00 ❗
Startup Time - 1 core	0.74 s (±0.02 s)	0.75 s (±0.02 s)	1.00
Startup Time - 2 cores	0.74 s (±0.02 s)	0.74 s (±0.02 s)	1.01
Startup Time - 4 cores	0.75 s (±0.04 s)	0.74 s (±0.02 s)	1.02
multithreaded_benchmark Build Time	82.65 s	82.11 s	1.01 ❗
multithreaded_benchmark File Size	0.86 MB	0.86 MB	1.00 ❗
Multithreaded Pi Efficiency - 2 Threads	86.93 % (±5.48 %)	85.89 % (±6.61 %)	1.01
Multithreaded Pi Efficiency - 4 Threads	42.83 % (±2.51 %)	43.43 % (±2.56 %)	0.99
Multithreaded Pi Efficiency - 8 Threads	24.84 % (±1.40 %)	25.76 % (±1.53 %)	0.96
micro_benchmarks Build Time	82.58 s	80.40 s	1.03 ❗
micro_benchmarks File Size	0.86 MB	0.86 MB	1.00 ❗
Scheduling time - 1 thread	62.12 ticks (±2.40 ticks)	62.65 ticks (±4.06 ticks)	0.99
Scheduling time - 2 threads	34.11 ticks (±4.17 ticks)	34.08 ticks (±4.10 ticks)	1.00
Micro - Time for syscall (getpid)	3.39 ticks (±0.47 ticks)	3.45 ticks (±0.58 ticks)	0.98
Memcpy speed - (built_in) block size 4096	82125.64 MByte/s (±56878.20 MByte/s)	82448.38 MByte/s (±56997.13 MByte/s)	1.00
Memcpy speed - (built_in) block size 1048576	30357.34 MByte/s (±24500.01 MByte/s)	30585.98 MByte/s (±24707.84 MByte/s)	0.99
Memcpy speed - (built_in) block size 16777216	26948.19 MByte/s (±22286.99 MByte/s)	26340.06 MByte/s (±21720.96 MByte/s)	1.02
Memset speed - (built_in) block size 4096	82538.30 MByte/s (±57151.08 MByte/s)	82292.76 MByte/s (±56891.50 MByte/s)	1.00
Memset speed - (built_in) block size 1048576	31096.80 MByte/s (±24932.98 MByte/s)	31323.85 MByte/s (±25145.86 MByte/s)	0.99
Memset speed - (built_in) block size 16777216	27684.14 MByte/s (±22734.82 MByte/s)	27104.68 MByte/s (±22209.94 MByte/s)	1.02
Memcpy speed - (rust) block size 4096	75107.74 MByte/s (±52373.82 MByte/s)	74097.96 MByte/s (±51811.44 MByte/s)	1.01
Memcpy speed - (rust) block size 1048576	30402.19 MByte/s (±24619.41 MByte/s)	30361.60 MByte/s (±24602.37 MByte/s)	1.00
Memcpy speed - (rust) block size 16777216	25863.16 MByte/s (±21294.74 MByte/s)	27625.34 MByte/s (±22806.88 MByte/s)	0.94
Memset speed - (rust) block size 4096	75045.73 MByte/s (±52336.97 MByte/s)	74373.47 MByte/s (±51976.48 MByte/s)	1.01
Memset speed - (rust) block size 1048576	31143.13 MByte/s (±25047.95 MByte/s)	31110.89 MByte/s (±25033.24 MByte/s)	1.00
Memset speed - (rust) block size 16777216	26626.58 MByte/s (±21794.27 MByte/s)	28386.93 MByte/s (±23265.03 MByte/s)	0.94
alloc_benchmarks Build Time	78.60 s	74.76 s	1.05 ❗
alloc_benchmarks File Size	0.87 MB	0.87 MB	1.00 ❗
Allocations - Allocation success	91.31 %	91.31 %	1
Allocations - Deallocation success	100.00 %	100.00 %	1
Allocations - Pre-fail Allocations	61.44 %	61.44 %	1
Allocations - Average Allocation time	7755.99 Ticks (±144.27 Ticks)	5860.58 Ticks (±98.43 Ticks)	1.32 ❗
Allocations - Average Allocation time (no fail)	8221.42 Ticks (±152.18 Ticks)	6554.81 Ticks (±92.86 Ticks)	1.25 ❗
Allocations - Average Deallocation time	1433.12 Ticks (±505.07 Ticks)	1805.01 Ticks (±250.35 Ticks)	0.79
mutex_benchmark Build Time	77.70 s	79.82 s	0.97 ❗
mutex_benchmark File Size	0.86 MB	0.86 MB	1.00 ❗
Mutex Stress Test Average Time per Iteration - 1 Threads	12.14 ns (±0.40 ns)	12.10 ns (±0.41 ns)	1.00
Mutex Stress Test Average Time per Iteration - 2 Threads	42.14 ns (±1.99 ns)	40.26 ns (±1.68 ns)	1.05

This comment was automatically generated by workflow using github-action-benchmark.

[mkroening]

Thanks for the PR! :)

I was wondering why implement drivers for legacy devices instead of USB keyboards (xhci, usb-oxide, embassy-usb). I guess it is because of simplicity.

It would be great to discuss the high-level application-facing API, since that is the hardest to change once merged.

[mkroening]

Could you rename this to pc-keyboard? Also, please make sure that the docs don't imply that this is needed for keyboard support in general. Serial-based keyboard support is separate from this. Similar to the framebuffer, please also put a disclaimer that this does not make the kernel use the driver and instead exposes an API for applications that need to be ported.

[mkroening]

Please move the allow to the function level instead of having it inline like this.

[mkroening]

Suggested change

	use crate::arch::kernel::keyboard::get_keyboard_handler;
	use crate::arch::kernel::keyboard::get_keyboard_handler;

[mkroening]

Please move the handler to the top level outside of this function.

[mkroening]

Why do we discard the device buffer instead of filling our read buffer?

[mkroening]

Do you think an abstraction similar to the proposal for BGA would make sense?

struct Ps2;

impl Ps2 {
    fn read_data() -> u8;
    fn write_data(data: u8);
    fn status() -> u8;
    fn command(command: u8);
}

[mkroening]

A scancode can never be zero, right? Returning Option<NonZero<u8>> would be preferable in that case.

[mkroening]

I am not too sure about this API. Is the application supposed to busy loop on this and retrieve one event at a time?

What about doing something similar to Linux's event device (evdev) interface (Linux docs)? Reading from /dev/input/event0 would then fill a user buffer with input events and blocks if no events are there unless opened with O_NONBLOCK.