/* Copyright 2014 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 "clock.h"
#include "common.h"
#include "console.h"
#include "dma.h"
#include "hooks.h"
#include "hwtimer.h"
#include "registers.h"
#include "task.h"
#include "timer.h"
#include "util.h"

struct mutex adc_lock;

struct adc_profile_t {
	/* Register values. */
	uint32_t cfgr1_reg;
	uint32_t cfgr2_reg;
	uint32_t smpr_reg;	/* Default Sampling Rate */
	uint32_t ier_reg;
	/* DMA config. */
	const struct dma_option *dma_option;
	/* Size of DMA buffer, in units of ADC_CH_COUNT. */
	int dma_buffer_size;
};

#ifdef CONFIG_ADC_PROFILE_SINGLE
static const struct dma_option dma_single = {
	STM32_DMAC_ADC, (void *)&STM32_ADC_DR,
	STM32_DMA_CCR_MSIZE_32_BIT | STM32_DMA_CCR_PSIZE_32_BIT,
};

#ifndef CONFIG_ADC_SAMPLE_TIME
#define CONFIG_ADC_SAMPLE_TIME STM32_ADC_SMPR_13_5_CY
#endif

static const struct adc_profile_t profile = {
	/* Sample all channels once using DMA */
	.cfgr1_reg = STM32_ADC_CFGR1_OVRMOD,
	.cfgr2_reg = 0,
	.smpr_reg = CONFIG_ADC_SAMPLE_TIME,
	.ier_reg = 0,
	.dma_option = &dma_single,
	.dma_buffer_size = 1,
};
#endif

#ifdef CONFIG_ADC_PROFILE_FAST_CONTINUOUS

#ifndef CONFIG_ADC_SAMPLE_TIME
#define CONFIG_ADC_SAMPLE_TIME STM32_ADC_SMPR_1_5_CY
#endif

static const struct dma_option dma_continuous = {
	STM32_DMAC_ADC, (void *)&STM32_ADC_DR,
	STM32_DMA_CCR_MSIZE_32_BIT | STM32_DMA_CCR_PSIZE_32_BIT |
	STM32_DMA_CCR_CIRC,
};

static const struct adc_profile_t profile = {
	/* Sample all channels continuously using DMA */
	.cfgr1_reg = STM32_ADC_CFGR1_OVRMOD |
		     STM32_ADC_CFGR1_CONT |
		     STM32_ADC_CFGR1_DMACFG,
	.cfgr2_reg = 0,
	.smpr_reg = CONFIG_ADC_SAMPLE_TIME,
	/* Fire interrupt at end of sequence. */
	.ier_reg = STM32_ADC_IER_EOSEQIE,
	.dma_option = &dma_continuous,
	/* Double-buffer our samples. */
	.dma_buffer_size = 2,
};
#endif

static void adc_init(const struct adc_t *adc)
{
	/*
	 * If clock is already enabled, and ADC module is enabled
	 * then this is a warm reboot and ADC is already initialized.
	 */
	if (STM32_RCC_APB2ENR & BIT(9) && (STM32_ADC_CR & STM32_ADC_CR_ADEN))
		return;

	/* Enable ADC clock */
	clock_enable_module(MODULE_ADC, 1);
	/* check HSI14 in RCC ? ON by default */

	/* ADC calibration (done with ADEN = 0) */
	STM32_ADC_CR = STM32_ADC_CR_ADCAL; /* set ADCAL = 1, ADC off */
	/* wait for the end of calibration */
	while (STM32_ADC_CR & STM32_ADC_CR_ADCAL)
		;

	/* Single conversion, right aligned, 12-bit */
	STM32_ADC_CFGR1 = profile.cfgr1_reg;
	/* clock is ADCCLK (ADEN must be off when writing this reg) */
	STM32_ADC_CFGR2 = profile.cfgr2_reg;

	/*
	 * ADC enable (note: takes 4 ADC clocks between end of calibration
	 * and setting ADEN).
	 */
	STM32_ADC_CR = STM32_ADC_CR_ADEN;
	while (!(STM32_ADC_ISR & STM32_ADC_ISR_ADRDY))
		STM32_ADC_CR = STM32_ADC_CR_ADEN;
}

static void adc_configure(int ain_id, enum stm32_adc_smpr sample_rate)
{
	/* Sampling time */
	if (sample_rate == STM32_ADC_SMPR_DEFAULT ||
			sample_rate >= STM32_ADC_SMPR_COUNT)
		STM32_ADC_SMPR = profile.smpr_reg;
	else
		STM32_ADC_SMPR = STM32_ADC_SMPR_SMP(sample_rate);

	/* Select channel to convert */
	STM32_ADC_CHSELR = BIT(ain_id);

	/* Disable DMA */
	STM32_ADC_CFGR1 &= ~STM32_ADC_CFGR1_DMAEN;
}

#ifdef CONFIG_ADC_WATCHDOG

static int watchdog_ain_id;
static int watchdog_delay_ms;

static void adc_continuous_read(int ain_id)
{
	adc_configure(ain_id, STM32_ADC_SMPR_DEFAULT);

	/* CONT=1 -> continuous mode on */
	STM32_ADC_CFGR1 |= STM32_ADC_CFGR1_CONT;

	/* Start continuous conversion */
	STM32_ADC_CR |= BIT(2); /* ADSTART */
}

static void adc_continuous_stop(void)
{
	/* Stop on-going conversion */
	STM32_ADC_CR |= BIT(4); /* ADSTP */

	/* Wait for conversion to stop */
	while (STM32_ADC_CR & BIT(4))
		;

	/* CONT=0 -> continuous mode off */
	STM32_ADC_CFGR1 &= ~STM32_ADC_CFGR1_CONT;
}

static void adc_interval_read(int ain_id, int interval_ms)
{
	adc_configure(ain_id, STM32_ADC_SMPR_DEFAULT);

	/* EXTEN=01 -> hardware trigger detection on rising edge */
	STM32_ADC_CFGR1 = (STM32_ADC_CFGR1 & ~STM32_ADC_CFGR1_EXTEN_MASK)
		| STM32_ADC_CFGR1_EXTEN_RISE;

	/* EXTSEL=TRG3 -> Trigger on TIM3_TRGO */
	STM32_ADC_CFGR1 = (STM32_ADC_CFGR1 & ~STM32_ADC_CFGR1_TRG_MASK) |
		STM32_ADC_CFGR1_TRG3;

	__hw_timer_enable_clock(TIM_ADC, 1);

	/* Upcounter, counter disabled, update event only on underflow */
	STM32_TIM_CR1(TIM_ADC) = 0x0004;

	/* TRGO on update event */
	STM32_TIM_CR2(TIM_ADC) = 0x0020;
	STM32_TIM_SMCR(TIM_ADC) = 0x0000;

	/* Auto-reload value */
	STM32_TIM_ARR(TIM_ADC) = interval_ms & 0xffff;

	/* Set prescaler to tick per millisecond */
	STM32_TIM_PSC(TIM_ADC) = (clock_get_freq() / MSEC) - 1;

	/* Start counting */
	STM32_TIM_CR1(TIM_ADC) |= 1;

	/* Start ADC conversion */
	STM32_ADC_CR |= BIT(2); /* ADSTART */
}

static void adc_interval_stop(void)
{
	/* EXTEN=00 -> hardware trigger detection disabled */
	STM32_ADC_CFGR1 &= ~STM32_ADC_CFGR1_EXTEN_MASK;

	/* Set ADSTP to clear ADSTART */
	STM32_ADC_CR |= BIT(4); /* ADSTP */

	/* Wait for conversion to stop */
	while (STM32_ADC_CR & BIT(4))
		;

	/* Stop the timer */
	STM32_TIM_CR1(TIM_ADC) &= ~0x1;
}

static int adc_watchdog_enabled(void)
{
	return STM32_ADC_CFGR1 & STM32_ADC_CFGR1_AWDEN;
}

static int adc_enable_watchdog_no_lock(void)
{
	/* Select channel */
	STM32_ADC_CFGR1 = (STM32_ADC_CFGR1 & ~STM32_ADC_CFGR1_AWDCH_MASK) |
			  (watchdog_ain_id << 26);
	adc_configure(watchdog_ain_id, STM32_ADC_SMPR_DEFAULT);

	/* Clear AWD interrupt flag */
	STM32_ADC_ISR = 0x80;
	/* Set Watchdog enable bit on a single channel */
	STM32_ADC_CFGR1 |= STM32_ADC_CFGR1_AWDEN | STM32_ADC_CFGR1_AWDSGL;
	/* Enable interrupt */
	STM32_ADC_IER |= STM32_ADC_IER_AWDIE;

	if (watchdog_delay_ms)
		adc_interval_read(watchdog_ain_id, watchdog_delay_ms);
	else
		adc_continuous_read(watchdog_ain_id);

	return EC_SUCCESS;
}

int adc_enable_watchdog(int ain_id, int high, int low)
{
	int ret;

	mutex_lock(&adc_lock);

	watchdog_ain_id = ain_id;

	/* Set thresholds */
	STM32_ADC_TR = ((high & 0xfff) << 16) | (low & 0xfff);

	ret = adc_enable_watchdog_no_lock();
	mutex_unlock(&adc_lock);
	return ret;
}

static int adc_disable_watchdog_no_lock(void)
{
	if (watchdog_delay_ms)
		adc_interval_stop();
	else
		adc_continuous_stop();

	/* Clear Watchdog enable bit */
	STM32_ADC_CFGR1 &= ~STM32_ADC_CFGR1_AWDEN;

	return EC_SUCCESS;
}

int adc_disable_watchdog(void)
{
	int ret;

	mutex_lock(&adc_lock);
	ret = adc_disable_watchdog_no_lock();
	mutex_unlock(&adc_lock);

	return ret;
}

int adc_set_watchdog_delay(int delay_ms)
{
	int resume_watchdog = 0;

	mutex_lock(&adc_lock);
	if (adc_watchdog_enabled()) {
		resume_watchdog = 1;
		adc_disable_watchdog_no_lock();
	}

	watchdog_delay_ms = delay_ms;

	if (resume_watchdog)
		adc_enable_watchdog_no_lock();
	mutex_unlock(&adc_lock);

	return EC_SUCCESS;
}

#else /* CONFIG_ADC_WATCHDOG */

static int adc_watchdog_enabled(void) { return 0; }
static int adc_enable_watchdog_no_lock(void) { return 0; }
static int adc_disable_watchdog_no_lock(void) { return 0; }

#endif /* CONFIG_ADC_WATCHDOG */

int adc_read_channel(enum adc_channel ch)
{
	const struct adc_t *adc = adc_channels + ch;
	int value;
	int restore_watchdog = 0;

	mutex_lock(&adc_lock);

	adc_init(adc);

	if (adc_watchdog_enabled()) {
		restore_watchdog = 1;
		adc_disable_watchdog_no_lock();
	}

	adc_configure(adc->channel, adc->sample_rate);

	/* Clear flags */
	STM32_ADC_ISR = 0xe;

	/* Start conversion */
	STM32_ADC_CR |= BIT(2); /* ADSTART */

	/* Wait for end of conversion */
	while (!(STM32_ADC_ISR & BIT(2)))
		;
	/* read converted value */
	value = STM32_ADC_DR;

	if (restore_watchdog)
		adc_enable_watchdog_no_lock();
	mutex_unlock(&adc_lock);

	return value * adc->factor_mul / adc->factor_div + adc->shift;
}

void adc_disable(void)
{
	STM32_ADC_CR |= STM32_ADC_CR_ADDIS;
	/*
	 * Note that the ADC is not in OFF state immediately.
	 * Once the ADC is effectively put into OFF state,
	 * STM32_ADC_CR_ADDIS bit will be cleared by hardware.
	 */
}