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// SPDX-FileCopyrightText: 2024 Himbeer <himbeer@disroot.org>
//
// SPDX-License-Identifier: AGPL-3.0-or-later
const hwinfo = @import("hwinfo.zig");
pub var default: Plic = undefined;
pub const Error = error{
InterruptOutOfRange,
ContextOutOfRange,
};
pub const Context = packed struct {
priority_threshold: u32,
claim_or_complete: u32,
};
pub const Plic = struct {
mmio_register: hwinfo.Reg,
const priority_offset = 0x0;
const enable_offset = 0x2000;
const context_offset_zero = 0x200000;
const context_offset_nonzero = 0x201000;
pub const num_contexts = 15872;
// A value greater than or equal to num_contexts for context is an error.
// A value of 0 for interrupt results in an error.
pub fn setEnabled(self: Plic, context: u14, interrupt: u10, enable: bool) !void {
if (context >= num_contexts) return Error.ContextOutOfRange;
if (interrupt == 0) return Error.InterruptOutOfRange;
const mmio_slice = self.mmioSlice();
const enable_ptr: *volatile [num_contexts][32]u32 = @alignCast(@ptrCast(&mmio_slice[enable_offset]));
const register = interrupt / 32;
const bit = @as(u32, 1) << @intCast(interrupt & 0x1f);
if (enable) {
enable_ptr[context][register] |= bit;
} else {
enable_ptr[context][register] &= ~bit;
}
}
// A value of 0 for interrupt results in an error.
pub fn setPriority(self: Plic, interrupt: u10, priority: u3) !void {
if (interrupt == 0) return Error.InterruptOutOfRange;
const mmio_slice = self.mmioSlice();
const priority_ptr: *volatile [1024]u32 = @alignCast(@ptrCast(&mmio_slice[priority_offset]));
priority_ptr[interrupt] = @intCast(priority);
}
// A value greater than or equal to num_contexts for context is an error.
pub fn setPriorityThreshold(self: Plic, context: u14, threshold: u3) !void {
const context_ptr = try self.contextPtr(context);
context_ptr.priority_threshold = threshold;
}
// A value greater than or equal to num_contexts for context is an error.
// Non-null interrupts are guaranteed to be non-zero.
pub fn claim(self: Plic, context: u14) !?u10 {
const context_ptr = try self.contextPtr(context);
const interrupt = context_ptr.claim_or_complete;
if (interrupt != 0) return @intCast(interrupt) else return null;
}
// A value greater than or equal to num_contexts for context is an error.
// A value of 0 for interrupt results in an error.
pub fn complete(self: Plic, context: u14, interrupt: u10) !void {
if (interrupt == 0) return Error.InterruptOutOfRange;
const context_ptr = try self.contextPtr(context);
context_ptr.claim_or_complete = interrupt;
}
fn contextPtr(self: Plic, context: u14) !*volatile Context {
if (context >= num_contexts) return Error.ContextOutOfRange;
const mmio_slice = self.mmio_register.slice(u8);
if (context == 0) {
return @alignCast(@ptrCast(&mmio_slice[context_offset_zero]));
} else {
const context_offset: usize = context - 1;
const ptr_offset = context_offset * (@sizeOf(u32) + @sizeOf(Context));
const context_ptr = &mmio_slice[context_offset_nonzero + ptr_offset];
return @alignCast(@ptrCast(context_ptr));
}
}
};
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