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use core::cell::Cell;
use kernel::{AppId, Callback, Driver, ReturnCode};
use kernel::common::take_cell::TakeCell;
use kernel::hil::i2c;
pub static mut BUFFER: [u8; 5] = [0; 5];
#[derive(Clone, Copy, PartialEq)]
enum State {
Idle,
ReadControl(ControlField),
Done,
}
#[derive(Clone, Copy, PartialEq)]
enum ControlField {
InterruptMask,
SelectedChannels,
}
pub struct PCA9544A<'a> {
i2c: &'a i2c::I2CDevice,
state: Cell<State>,
buffer: TakeCell<'static, [u8]>,
callback: Cell<Option<Callback>>,
}
impl<'a> PCA9544A<'a> {
pub fn new(i2c: &'a i2c::I2CDevice, buffer: &'static mut [u8]) -> PCA9544A<'a> {
PCA9544A {
i2c: i2c,
state: Cell::new(State::Idle),
buffer: TakeCell::new(buffer),
callback: Cell::new(None),
}
}
fn select_channels(&self, channel_bitmask: u8) -> ReturnCode {
self.buffer.take().map_or(ReturnCode::ENOMEM, |buffer| {
self.i2c.enable();
buffer[0] = 0;
let mut index = 1;
for i in 0..4 {
if channel_bitmask & (0x01 << i) != 0 {
buffer[index] = i + 4;
index += 1;
}
}
self.i2c.write(buffer, index as u8);
self.state.set(State::Done);
ReturnCode::SUCCESS
})
}
fn read_interrupts(&self) -> ReturnCode {
self.read_control(ControlField::InterruptMask)
}
fn read_selected_channels(&self) -> ReturnCode {
self.read_control(ControlField::SelectedChannels)
}
fn read_control(&self, field: ControlField) -> ReturnCode {
self.buffer.take().map_or(ReturnCode::ENOMEM, |buffer| {
self.i2c.enable();
self.i2c.read(buffer, 1);
self.state.set(State::ReadControl(field));
ReturnCode::SUCCESS
})
}
}
impl<'a> i2c::I2CClient for PCA9544A<'a> {
fn command_complete(&self, buffer: &'static mut [u8], _error: i2c::Error) {
match self.state.get() {
State::ReadControl(field) => {
let ret = match field {
ControlField::InterruptMask => (buffer[0] >> 4) & 0x0F,
ControlField::SelectedChannels => buffer[0] & 0x07,
};
self.callback
.get()
.map(|mut cb| cb.schedule((field as usize) + 1, ret as usize, 0));
self.buffer.replace(buffer);
self.i2c.disable();
self.state.set(State::Idle);
}
State::Done => {
self.callback.get().map(|mut cb| cb.schedule(0, 0, 0));
self.buffer.replace(buffer);
self.i2c.disable();
self.state.set(State::Idle);
}
_ => {}
}
}
}
impl<'a> Driver for PCA9544A<'a> {
fn subscribe(&self, subscribe_num: usize, callback: Callback) -> ReturnCode {
match subscribe_num {
0 => {
self.callback.set(Some(callback));
ReturnCode::SUCCESS
}
_ => ReturnCode::ENOSUPPORT,
}
}
fn command(&self, command_num: usize, data: usize, _: usize, _: AppId) -> ReturnCode {
match command_num {
0 => ReturnCode::SUCCESS,
1 => self.select_channels(data as u8),
2 => self.select_channels(0),
3 => self.read_interrupts(),
4 => self.read_selected_channels(),
_ => ReturnCode::ENOSUPPORT,
}
}
}