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use core::cell::Cell;
use kernel::common::VolatileCell;
use kernel::hil::rng::{self, Continue};
use pm;
#[repr(C)]
struct Registers {
control: VolatileCell<u32>,
_reserved0: [u32; 3],
interrupt_enable: VolatileCell<u32>,
interrupt_disable: VolatileCell<u32>,
interrupt_mask: VolatileCell<u32>,
interrupt_status: VolatileCell<u32>,
_reserved1: [u32; 12],
data: VolatileCell<u32>,
}
const BASE_ADDRESS: *const Registers = 0x40068000 as *const Registers;
pub struct Trng<'a> {
regs: *const Registers,
client: Cell<Option<&'a rng::Client>>,
}
pub static mut TRNG: Trng<'static> = Trng::new();
const KEY: u32 = 0x524e4700;
impl<'a> Trng<'a> {
const fn new() -> Trng<'a> {
Trng {
regs: BASE_ADDRESS,
client: Cell::new(None),
}
}
pub fn handle_interrupt(&self) {
let regs = unsafe { &*self.regs };
if regs.interrupt_mask.get() == 0 {
return;
}
regs.interrupt_disable.set(1);
self.client.get().map(|client| {
let result = client.randomness_available(&mut TrngIter(self));
if let Continue::Done = result {
regs.control.set(KEY | 0);
unsafe {
pm::disable_clock(pm::Clock::PBA(pm::PBAClock::TRNG));
}
} else {
regs.interrupt_enable.set(1);
}
});
}
pub fn set_client(&self, client: &'a rng::Client) {
self.client.set(Some(client));
}
}
struct TrngIter<'a, 'b: 'a>(&'a Trng<'b>);
impl<'a, 'b> Iterator for TrngIter<'a, 'b> {
type Item = u32;
fn next(&mut self) -> Option<u32> {
let regs = unsafe { &*self.0.regs };
if regs.interrupt_status.get() != 0 {
Some(regs.data.get())
} else {
None
}
}
}
impl<'a> rng::RNG for Trng<'a> {
fn get(&self) {
let regs = unsafe { &*self.regs };
unsafe {
pm::enable_clock(pm::Clock::PBA(pm::PBAClock::TRNG));
}
regs.control.set(KEY | 1);
regs.interrupt_enable.set(1);
}
}