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