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/* Copyright 2013 The Chromium OS Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "adc.h"
#include "common.h"
#include "console.h"
#include "hooks.h"
#include "registers.h"
#include "task.h"
#include "timer.h"
#include "util.h"
/*
* Conversion on a single channel takes less than 12 ms. Set timeout to
* 15 ms so that we have a 3-ms margin.
*/
#define ADC_SINGLE_READ_TIME 15000
struct mutex adc_lock;
static volatile task_id_t task_waiting;
static int start_single_and_wait(int timeout)
{
int event;
task_waiting = task_get_current();
/* Start conversion */
MEC1322_ADC_CTRL |= BIT(1);
/* Wait for interrupt */
event = task_wait_event(timeout);
task_waiting = TASK_ID_INVALID;
return event != TASK_EVENT_TIMER;
}
int adc_read_channel(enum adc_channel ch)
{
const struct adc_t *adc = adc_channels + ch;
int value;
mutex_lock(&adc_lock);
MEC1322_ADC_SINGLE = 1 << adc->channel;
if (start_single_and_wait(ADC_SINGLE_READ_TIME))
value = MEC1322_ADC_READ(adc->channel) * adc->factor_mul /
adc->factor_div + adc->shift;
else
value = ADC_READ_ERROR;
mutex_unlock(&adc_lock);
return value;
}
static void adc_init(void)
{
/* Activate ADC module */
MEC1322_ADC_CTRL |= BIT(0);
/* Enable interrupt */
task_waiting = TASK_ID_INVALID;
MEC1322_INT_ENABLE(17) |= BIT(10);
MEC1322_INT_BLK_EN |= BIT(17);
task_enable_irq(MEC1322_IRQ_ADC_SNGL);
}
DECLARE_HOOK(HOOK_INIT, adc_init, HOOK_PRIO_INIT_ADC);
void adc_interrupt(void)
{
/* Clear interrupt status bit */
MEC1322_ADC_CTRL |= BIT(7);
if (task_waiting != TASK_ID_INVALID)
task_wake(task_waiting);
}
DECLARE_IRQ(MEC1322_IRQ_ADC_SNGL, adc_interrupt, 2);
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