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/* Copyright 2017 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 "gpio.h"
#include "hooks.h"
#include "registers.h"
#include "task.h"
#include "timer.h"
#include "util.h"
#include "tfdp_chip.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;
/*
* Volatile should not be needed.
* ADC ISR only reads task_waiting.
* Two other non-ISR routines only write task_waiting when
* interrupt is disabled or before starting ADC.
*/
static task_id_t task_waiting;
/*
* Start ADC single-shot conversion.
* 1. Disable ADC interrupt.
* 2. Clear sticky hardware status.
* 3. Start conversion.
* 4. Enable interrupt.
* 5. Wait with timeout for ADC ISR to
* to set TASK_EVENT_TIMER.
*/
static int start_single_and_wait(int timeout)
{
int event;
MCHP_INT_DISABLE(MCHP_ADC_GIRQ) = MCHP_ADC_GIRQ_SINGLE_BIT;
task_waiting = task_get_current();
/* clear all R/W1C channel status */
MCHP_ADC_STS = 0xffffu;
/* clear R/W1C single done status */
MCHP_ADC_CTRL |= BIT(7);
/* clear GIRQ single status */
MCHP_INT_SOURCE(MCHP_ADC_GIRQ) = MCHP_ADC_GIRQ_SINGLE_BIT;
/* make sure all writes are issued before starting conversion */
asm volatile ("dsb");
/* Start conversion */
MCHP_ADC_CTRL |= BIT(1);
MCHP_INT_ENABLE(MCHP_ADC_GIRQ) = MCHP_ADC_GIRQ_SINGLE_BIT;
/* Wait for interrupt, ISR disables 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);
MCHP_ADC_SINGLE = 1 << adc->channel;
if (start_single_and_wait(ADC_SINGLE_READ_TIME))
value = (MCHP_ADC_READ(adc->channel) * adc->factor_mul) /
adc->factor_div + adc->shift;
else
value = ADC_READ_ERROR;
mutex_unlock(&adc_lock);
return value;
}
int adc_read_all_channels(int *data)
{
int i;
int ret = EC_SUCCESS;
const struct adc_t *adc;
mutex_lock(&adc_lock);
MCHP_ADC_SINGLE = 0;
for (i = 0; i < ADC_CH_COUNT; ++i)
MCHP_ADC_SINGLE |= 1 << adc_channels[i].channel;
if (!start_single_and_wait(ADC_SINGLE_READ_TIME * ADC_CH_COUNT)) {
ret = EC_ERROR_TIMEOUT;
goto exit_all_channels;
}
for (i = 0; i < ADC_CH_COUNT; ++i) {
adc = adc_channels + i;
data[i] = (MCHP_ADC_READ(adc->channel) * adc->factor_mul) /
adc->factor_div + adc->shift;
}
exit_all_channels:
mutex_unlock(&adc_lock);
return ret;
}
/*
* Enable GPIO pins.
* Using MEC17xx direct mode interrupts. Do not
* set Interrupt Aggregator Block Enable bit
* for GIRQ containing ADC.
*/
static void adc_init(void)
{
trace0(0, ADC, 0, "adc_init");
gpio_config_module(MODULE_ADC, 1);
/* clear ADC sleep enable */
MCHP_PCR_SLP_DIS_DEV(MCHP_PCR_ADC);
/* Activate ADC module */
MCHP_ADC_CTRL |= BIT(0);
/* Enable interrupt */
task_waiting = TASK_ID_INVALID;
MCHP_INT_ENABLE(MCHP_ADC_GIRQ) = MCHP_ADC_GIRQ_SINGLE_BIT;
task_enable_irq(MCHP_IRQ_ADC_SNGL);
}
DECLARE_HOOK(HOOK_INIT, adc_init, HOOK_PRIO_INIT_ADC);
void adc_interrupt(void)
{
MCHP_INT_DISABLE(MCHP_ADC_GIRQ) = MCHP_ADC_GIRQ_SINGLE_BIT;
/* clear individual chan conversion status */
MCHP_ADC_STS = 0xffffu;
/* Clear interrupt status bit */
MCHP_ADC_CTRL |= BIT(7);
MCHP_INT_SOURCE(MCHP_ADC_GIRQ) = MCHP_ADC_GIRQ_SINGLE_BIT;
if (task_waiting != TASK_ID_INVALID)
task_wake(task_waiting);
}
DECLARE_IRQ(MCHP_IRQ_ADC_SNGL, adc_interrupt, 2);
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