runtime: rewrite i2c support code in Rust.

This commit is contained in:
whitequark 2016-11-21 18:25:43 +00:00
parent a825584ac0
commit 18b7ccea4e
6 changed files with 173 additions and 209 deletions

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@ -105,9 +105,9 @@ static mut API: &'static [(&'static str, *const ())] = &[
api!(rtio_input_timestamp = ::rtio::input_timestamp),
api!(rtio_input_data = ::rtio::input_data),
api!(i2c_init),
api!(i2c_start),
api!(i2c_stop),
api!(i2c_write),
api!(i2c_read),
api!(i2c_init = ::i2c::init),
api!(i2c_start = ::i2c::start),
api!(i2c_stop = ::i2c::stop),
api!(i2c_write = ::i2c::write),
api!(i2c_read = ::i2c::read),
];

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@ -0,0 +1,166 @@
use board::csr;
fn half_period() {
unsafe {
csr::timer_kernel::en_write(0);
csr::timer_kernel::load_write(csr::CONFIG_CLOCK_FREQUENCY/10000);
csr::timer_kernel::reload_write(0);
csr::timer_kernel::en_write(1);
csr::timer_kernel::update_value_write(1);
while csr::timer_kernel::value_read() != 0 {
csr::timer_kernel::update_value_write(1)
}
}
}
#[cfg(has_i2c)]
mod imp {
use board::csr;
fn sda_bit(busno: u32) -> u32 { 1 << (2 * busno + 1) }
fn scl_bit(busno: u32) -> u32 { 1 << (2 * busno) }
pub fn sda_i(busno: u32) -> bool {
unsafe {
if busno >= csr::CONFIG_I2C_BUS_COUNT {
true
} else {
csr::i2c::in_read() & sda_bit(busno) != 0
}
}
}
pub fn sda_oe(busno: u32, oe: bool) {
unsafe {
let reg = csr::i2c::oe_read();
let reg = if oe { reg | sda_bit(busno) } else { reg & !sda_bit(busno) };
csr::i2c::oe_write(reg);
}
}
pub fn sda_o(busno: u32, o: bool) {
unsafe {
let reg = csr::i2c::out_read();
let reg = if o { reg | sda_bit(busno) } else { reg & !sda_bit(busno) };
csr::i2c::out_write(reg)
}
}
pub fn scl_oe(busno: u32, oe: bool) {
unsafe {
let reg = csr::i2c::oe_read();
let reg = if oe { reg | scl_bit(busno) } else { reg & !scl_bit(busno) };
csr::i2c::oe_write(reg)
}
}
pub fn scl_o(busno: u32, o: bool) {
unsafe {
let reg = csr::i2c::out_read();
let reg = if o { reg | scl_bit(busno) } else { reg & !scl_bit(busno) };
csr::i2c::out_write(reg)
}
}
}
// #[cfg(not(has_i2c))]
// mod imp {
// pub fn sda_i(busno: u32) -> bool { true }
// pub fn sda_oe(busno: u32, oe: bool) {}
// pub fn sda_o(busno: u32, o: bool) {}
// pub fn scl_oe(busno: u32, oe: bool) {}
// pub fn scl_o(busno: u32, o: bool) {}
// }
use self::imp::*;
pub extern fn init(busno: u32) {
// Set SCL as output, and high level
scl_o(busno, true);
scl_oe(busno, true);
// Prepare a zero level on SDA so that sda_oe pulls it down
sda_o(busno, false);
// Release SDA
sda_oe(busno, false);
// Check the I2C bus is ready
half_period();
half_period();
if !sda_i(busno) {
artiq_raise!("I2CError", "SDA is stuck low")
}
}
pub extern fn start(busno: u32) {
// Set SCL high then SDA low
scl_o(busno, true);
half_period();
sda_oe(busno, true);
half_period();
}
pub extern fn stop(busno: u32) {
// First, make sure SCL is low, so that the target releases the SDA line
scl_o(busno, false);
half_period();
// Set SCL high then SDA high
sda_oe(busno, true);
scl_o(busno, true);
half_period();
sda_oe(busno, false);
half_period();
}
pub extern fn write(busno: u32, data: u8) -> bool {
// MSB first
for bit in (0..8).rev() {
// Set SCL low and set our bit on SDA
scl_o(busno, false);
sda_oe(busno, data & (1 << bit) == 0);
half_period();
// Set SCL high ; data is shifted on the rising edge of SCL
scl_o(busno, true);
half_period();
}
// Check ack
// Set SCL low, then release SDA so that the I2C target can respond
scl_o(busno, false);
half_period();
sda_oe(busno, false);
// Set SCL high and check for ack
scl_o(busno, true);
half_period();
// returns true if acked (I2C target pulled SDA low)
!sda_i(busno)
}
pub extern fn read(busno: u32, ack: bool) -> u8 {
// Set SCL low first, otherwise setting SDA as input may cause a transition
// on SDA with SCL high which will be interpreted as START/STOP condition.
scl_o(busno, false);
half_period(); // make sure SCL has settled low
sda_oe(busno, false);
let mut data: u8 = 0;
// MSB first
for bit in (0..8).rev() {
scl_o(busno, false);
half_period();
// Set SCL high and shift data
scl_o(busno, true);
half_period();
if sda_i(busno) { data |= 1 << bit }
}
// Send ack
// Set SCL low and pull SDA low when acking
scl_o(busno, false);
if ack { sda_oe(busno, true) }
half_period();
// then set SCL high
scl_o(busno, true);
half_period();
data
}

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@ -50,6 +50,7 @@ macro_rules! artiq_raise {
}
mod rtio;
mod i2c;
use core::{mem, ptr, slice, str};
use std::io::Cursor;

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@ -4,7 +4,7 @@ include $(MISOC_DIRECTORY)/software/common.mak
PYTHON ?= python3.5
OBJECTS := flash_storage.o main.o
OBJECTS_KSUPPORT := ksupport_glue.o artiq_personality.o i2c.o
OBJECTS_KSUPPORT := ksupport_glue.o artiq_personality.o
RUSTOUT_DIRECTORY := cargo/or1k-unknown-none/debug
CORE_IO_COMMIT := d40c593f42fafbac1ff3d827f6df96338b5b7d8b

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@ -1,193 +0,0 @@
#include <generated/csr.h>
#include "artiq_personality.h"
#include "rtio.h"
#include "i2c.h"
static void i2c_halfperiod()
{
timer_kernel_en_write(0);
timer_kernel_load_write(CONFIG_CLOCK_FREQUENCY/10000);
timer_kernel_reload_write(0);
timer_kernel_en_write(1);
timer_kernel_update_value_write(1);
while(timer_kernel_value_read() != 0)
timer_kernel_update_value_write(1);
}
#if (defined CONFIG_I2C_BUS_COUNT) && (CONFIG_I2C_BUS_COUNT > 0)
#define SDA_BIT (1 << (2*busno + 1))
#define SCL_BIT (1 << (2*busno))
static int i2c_sda_i(int busno)
{
if(busno >= CONFIG_I2C_BUS_COUNT)
return 1;
else
return i2c_in_read() & SDA_BIT;
}
static void i2c_sda_oe(int busno, int oe)
{
int reg;
reg = i2c_oe_read();
if(oe)
reg |= SDA_BIT;
else
reg &= ~SDA_BIT;
i2c_oe_write(reg);
}
static void i2c_sda_o(int busno, int o)
{
int reg;
reg = i2c_out_read();
if(o)
reg |= SDA_BIT;
else
reg &= ~SDA_BIT;
i2c_out_write(reg);
}
static void i2c_scl_oe(int busno, int oe)
{
int reg;
reg = i2c_oe_read();
if(oe)
reg |= SCL_BIT;
else
reg &= ~SCL_BIT;
i2c_oe_write(reg);
}
static void i2c_scl_o(int busno, int o)
{
int reg;
reg = i2c_out_read();
if(o)
reg |= SCL_BIT;
else
reg &= ~SCL_BIT;
i2c_out_write(reg);
}
#else
static int i2c_sda_i(int busno)
{
return 1;
}
static void i2c_sda_oe(int busno, int oe) {}
static void i2c_sda_o(int busno, int o) {}
static void i2c_scl_oe(int busno, int oe) {}
static void i2c_scl_o(int busno, int o) {}
#endif
void i2c_init(int busno)
{
/* Set SCL as output, and high level */
i2c_scl_o(busno, 1);
i2c_scl_oe(busno, 1);
/* Prepare a zero level on SDA so that i2c_sda_oe pulls it down */
i2c_sda_o(busno, 0);
/* Release SDA */
i2c_sda_oe(busno, 0);
/* Check the I2C bus is ready */
i2c_halfperiod();
i2c_halfperiod();
if(!i2c_sda_i(busno))
artiq_raise_from_c("I2CError", "SDA is stuck low", 0, 0, 0);
}
void i2c_start(int busno)
{
/* Set SCL high then SDA low */
i2c_scl_o(busno, 1);
i2c_halfperiod();
i2c_sda_oe(busno, 1);
i2c_halfperiod();
}
void i2c_stop(int busno)
{
/* First, make sure SCL is low, so that the target releases the SDA line */
i2c_scl_o(busno, 0);
i2c_halfperiod();
/* Set SCL high then SDA high */
i2c_sda_oe(busno, 1);
i2c_scl_o(busno, 1);
i2c_halfperiod();
i2c_sda_oe(busno, 0);
i2c_halfperiod();
}
int i2c_write(int busno, int b)
{
int i;
/* MSB first */
for(i=7;i>=0;i--) {
/* Set SCL low and set our bit on SDA */
i2c_scl_o(busno, 0);
i2c_sda_oe(busno, b & (1 << i) ? 0 : 1);
i2c_halfperiod();
/* Set SCL high ; data is shifted on the rising edge of SCL */
i2c_scl_o(busno, 1);
i2c_halfperiod();
}
/* Check ack */
/* Set SCL low, then release SDA so that the I2C target can respond */
i2c_scl_o(busno, 0);
i2c_halfperiod();
i2c_sda_oe(busno, 0);
/* Set SCL high and check for ack */
i2c_scl_o(busno, 1);
i2c_halfperiod();
/* returns 1 if acked (I2C target pulled SDA low) */
return !i2c_sda_i(busno);
}
int i2c_read(int busno, int ack)
{
int i;
unsigned char b;
/* Set SCL low first, otherwise setting SDA as input may cause a transition
* on SDA with SCL high which will be interpreted as START/STOP condition.
*/
i2c_scl_o(busno, 0);
i2c_halfperiod(); /* make sure SCL has settled low */
i2c_sda_oe(busno, 0);
b = 0;
/* MSB first */
for(i=7;i>=0;i--) {
i2c_scl_o(busno, 0);
i2c_halfperiod();
/* Set SCL high and shift data */
i2c_scl_o(busno, 1);
i2c_halfperiod();
if(i2c_sda_i(busno)) b |= (1 << i);
}
/* Send ack */
/* Set SCL low and pull SDA low when acking */
i2c_scl_o(busno, 0);
if(ack)
i2c_sda_oe(busno, 1);
i2c_halfperiod();
/* then set SCL high */
i2c_scl_o(busno, 1);
i2c_halfperiod();
return b;
}

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@ -1,10 +0,0 @@
#ifndef __I2C_H
#define __I2C_H
void i2c_init(int busno);
void i2c_start(int busno);
void i2c_stop(int busno);
int i2c_write(int busno, int b);
int i2c_read(int busno, int ack);
#endif