/* This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */
/** library to control multiple software UARTs (code)
 *  @file uart_soft.c
 *  @author King Kévin <kingkevin@cuvoodoo.info>
 *  @date 2016
 *  @note peripherals used: GPIO @ref uart_soft_gpio, timer @ref uart_soft_timer
 */

/* standard libraries */
#include <stdint.h> // standard integer types
#include <stdlib.h> // general utilities

/* STM32 (including CM3) libraries */
#include <libopencm3/stm32/rcc.h> // real-time control clock library
#include <libopencm3/stm32/gpio.h> // general purpose input output library
#include <libopencm3/stm32/timer.h> // timer library
#include <libopencm3/cm3/nvic.h> // interrupt handler
#include <libopencm3/stm32/exti.h> // external interrupt defines

#include "uart_soft.h" // software UART library API
#include "global.h" // common methods

/** @defgroup uart_soft_gpio GPIO used for the software UART ports
 *  @note up to 4 pins supported, comment if unused
 *  @warning only one port must be used per line (pin number)
 *  @{
 */
#define UART_SOFT_RX_PORT0 B
#define UART_SOFT_RX_PIN0 9
//#define UART_SOFT_RX_PORT1 A
//#define UART_SOFT_RX_PIN1 0
//#define UART_SOFT_RX_PORT2 A
//#define UART_SOFT_RX_PIN2 0
//#define UART_SOFT_RX_PORT3 A
//#define UART_SOFT_RX_PIN3 0
//#define UART_SOFT_TX_PORT0 A
//#define UART_SOFT_TX_PIN0 0
//#define UART_SOFT_TX_PORT1 A
//#define UART_SOFT_TX_PIN1 0
//#define UART_SOFT_TX_PORT2 A
//#define UART_SOFT_TX_PIN2 0
//#define UART_SOFT_TX_PORT3 A
//#define UART_SOFT_TX_PIN3 0
/** @} */

/** @defgroup uart_soft_config UART configurations (2400-115200 bps)
 *  @note this implementation is designed for 8 bits, no parity, any stop configuration since this is the most common case
 *  @{
 */
#define UART_SOFT_RX_BAUDRATE0 9600
//#define UART_SOFT_RX_BAUDRATE1 0
//#define UART_SOFT_RX_BAUDRATE2 0
//#define UART_SOFT_RX_BAUDRATE3 0
//#define UART_SOFT_TX_BAUDRATE0 0
//#define UART_SOFT_TX_BAUDRATE1 0
//#define UART_SOFT_TX_BAUDRATE2 0
//#define UART_SOFT_TX_BAUDRATE3 0
/** @} */

/** @defgroup uart_soft_timer timer used to same UART signals
 *  @{
 */
#if (defined(UART_SOFT_RX_PORT0) && defined(UART_SOFT_RX_PIN0)) || (defined(UART_SOFT_RX_PORT1) && defined(UART_SOFT_RX_PIN1)) || (defined(UART_SOFT_RX_PORT2) && defined(UART_SOFT_RX_PIN2)) || (defined(UART_SOFT_RX_PORT3) && defined(UART_SOFT_RX_PIN0))
	#define UART_SOFT_RX_TIMER 3 /**< timer peripheral for receive signals */
#endif
#if (defined(UART_SOFT_TX_PORT0) && defined(UART_SOFT_TX_PIN0)) || (defined(UART_SOFT_TX_PORT1) && defined(UART_SOFT_TX_PIN1)) || (defined(UART_SOFT_TX_PORT2) && defined(UART_SOFT_TX_PIN2)) || (defined(UART_SOFT_TX_PORT3) && defined(UART_SOFT_TX_PIN0))
	#define UART_SOFT_TX_TIMER 4 /**< timer peripheral for transmit signals */
#endif
/** @} */

/** @defgroup uart_soft_state
 *  @{
 */
#if (defined(UART_SOFT_RX_PORT0) && defined(UART_SOFT_RX_PIN0))
volatile uint16_t rx0_state = 0; /**< state of the GPIO */
volatile uint8_t rx0_bit = 0; /**< next bit to receive */
volatile uint8_t rx0_byte = 0; /**< byte received */
#endif
/** @} */

bool uart_soft_setup(void)
{
	// verify configuration
	#if (defined(UART_SOFT_RX_BAUDRATE0) && ((UART_SOFT_RX_BAUDRATE0<2400) || (UART_SOFT_RX_BAUDRATE0>115200)))
		return false;
	#endif
	#if (defined(UART_SOFT_RX_BAUDRATE1) && ((UART_SOFT_RX_BAUDRATE1<2400) || (UART_SOFT_RX_BAUDRATE1>115200)))
		return false;
	#endif
	#if (defined(UART_SOFT_RX_BAUDRATE2) && ((UART_SOFT_RX_BAUDRATE2<2400) || (UART_SOFT_RX_BAUDRATE2>115200)))
		return false;
	#endif
	#if (defined(UART_SOFT_RX_BAUDRATE3) && ((UART_SOFT_RX_BAUDRATE3<2400) || (UART_SOFT_RX_BAUDRATE3>115200)))
		return false;
	#endif
	#if (defined(UART_SOFT_TX_BAUDRATE0) && ((UART_SOFT_TX_BAUDRATE0<2400) || (UART_SOFT_TX_BAUDRATE0>115200)))
		return false;
	#endif
	#if (defined(UART_SOFT_TX_BAUDRATE1) && ((UART_SOFT_TX_BAUDRATE1<2400) || (UART_SOFT_TX_BAUDRATE1>115200)))
		return false;
	#endif
	#if (defined(UART_SOFT_TX_BAUDRATE2) && ((UART_SOFT_TX_BAUDRATE2<2400) || (UART_SOFT_TX_BAUDRATE2>115200)))
		return false;
	#endif
	#if (defined(UART_SOFT_TX_BAUDRATE3) && ((UART_SOFT_TX_BAUDRATE3<2400) || (UART_SOFT_TX_BAUDRATE3>115200)))
		return false;
	#endif

	// setup GPIOs
	#if defined(UART_SOFT_RX_PORT0) && defined(UART_SOFT_RX_PIN0)
		rcc_periph_clock_enable(RCC_GPIO(UART_SOFT_RX_PORT0)); // enable clock for GPIO peripheral
		gpio_set_mode(GPIO(UART_SOFT_RX_PORT0), GPIO_MODE_INPUT, GPIO_CNF_INPUT_PULL_UPDOWN, GPIO(UART_SOFT_RX_PIN0)); // setup GPIO pin UART receive
		gpio_set(GPIO(UART_SOFT_RX_PORT0), GPIO(UART_SOFT_RX_PIN0)); // pull up to avoid noise when not connected
		rcc_periph_clock_enable(RCC_AFIO); // enable alternate function clock for external interrupt
		exti_select_source(EXTI(UART_SOFT_RX_PIN0), GPIO(UART_SOFT_RX_PORT0)); // mask external interrupt of this pin only for this port	
		exti_enable_request(EXTI(UART_SOFT_RX_PIN0)); // enable external interrupt
		exti_set_trigger(EXTI(UART_SOFT_RX_PIN0), EXTI_TRIGGER_BOTH); // trigger when button is pressed
		nvic_enable_irq(NVIC_EXTI_IRQ(UART_SOFT_RX_PIN0)); // enable interrupt
		rx0_state = gpio_get(GPIO(UART_SOFT_RX_PORT0), GPIO(UART_SOFT_RX_PIN0)); // save state of GPIO
		rx0_bit = 0; // reset bits received
	#endif
	#if defined(UART_SOFT_RX_PORT1) && defined(UART_SOFT_RX_PIN1)
		rcc_periph_clock_enable(RCC_GPIO(UART_SOFT_RX_PORT1)); // enable clock for GPIO peripheral
		gpio_set_mode(GPIO(UART_SOFT_RX_PORT1), GPIO_MODE_INPUT, GPIO_CNF_INPUT_PULL_UPDOWN, GPIO(UART_SOFT_RX_PIN1)); // setup GPIO pin UART receive
		gpio_set(GPIO(UART_SOFT_RX_PORT1), GPIO(UART_SOFT_RX_PIN1)); // pull up to avoid noise when not connected
	#endif
	#if defined(UART_SOFT_RX_PORT2) && defined(UART_SOFT_RX_PIN2)
		rcc_periph_clock_enable(RCC_GPIO(UART_SOFT_RX_PORT2)); // enable clock for GPIO peripheral
		gpio_set_mode(GPIO(UART_SOFT_RX_PORT2), GPIO_MODE_INPUT, GPIO_CNF_INPUT_PULL_UPDOWN, GPIO(UART_SOFT_RX_PIN2)); // setup GPIO pin UART receive
		gpio_set(GPIO(UART_SOFT_RX_PORT2), GPIO(UART_SOFT_RX_PIN2)); // pull up to avoid noise when not connected
	#endif
	#if defined(UART_SOFT_RX_PORT3) && defined(UART_SOFT_RX_PIN3)
		rcc_periph_clock_enable(RCC_GPIO(UART_SOFT_RX_PORT3)); // enable clock for GPIO peripheral
		gpio_set_mode(GPIO(UART_SOFT_RX_PORT3), GPIO_MODE_INPUT, GPIO_CNF_INPUT_PULL_UPDOWN, GPIO(UART_SOFT_RX_PIN3)); // setup GPIO pin UART receive
		gpio_set(GPIO(UART_SOFT_RX_PORT3), GPIO(UART_SOFT_RX_PIN3)); // pull up to avoid noise when not connected
	#endif
	#if defined(UART_SOFT_TX_PORT0) && defined(UART_SOFT_TX_PIN0)
		rcc_periph_clock_enable(RCC_GPIO(UART_SOFT_TX_PORT0)); // enable clock for GPIO peripheral
		gpio_set_mode(GPIO(UART_SOFT_TX_PORT0), GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, GPIO(UART_SOFT_TX_PIN0));
	#endif
	#if defined(UART_SOFT_TX_PORT1) && defined(UART_SOFT_TX_PIN1)
		rcc_periph_clock_enable(RCC_GPIO(UART_SOFT_TX_PORT1)); // enable clock for GPIO peripheral
		gpio_set_mode(GPIO(UART_SOFT_TX_PORT1), GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, GPIO(UART_SOFT_TX_PIN1));
	#endif
	#if defined(UART_SOFT_TX_PORT2) && defined(UART_SOFT_TX_PIN2)
		rcc_periph_clock_enable(RCC_GPIO(UART_SOFT_TX_PORT2)); // enable clock for GPIO peripheral
		gpio_set_mode(GPIO(UART_SOFT_TX_PORT2), GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, GPIO(UART_SOFT_TX_PIN2));
	#endif
	#if defined(UART_SOFT_TX_PORT3) && defined(UART_SOFT_TX_PIN3)
		rcc_periph_clock_enable(RCC_GPIO(UART_SOFT_TX_PORT3)); // enable clock for GPIO peripheral
		gpio_set_mode(GPIO(UART_SOFT_TX_PORT3), GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, GPIO(UART_SOFT_TX_PIN3));
	#endif

	// setup timer
	#if defined(UART_SOFT_RX_TIMER)
		rcc_periph_clock_enable(RCC_TIM(UART_SOFT_RX_TIMER)); // enable clock for timer peripheral
		timer_reset(TIM(UART_SOFT_RX_TIMER)); // reset timer state
		timer_set_mode(TIM(UART_SOFT_RX_TIMER), TIM_CR1_CKD_CK_INT, TIM_CR1_CMS_EDGE, TIM_CR1_DIR_UP); // set timer mode, use undivided timer clock, edge alignment (simple count), and count up
		timer_set_prescaler(TIM(UART_SOFT_RX_TIMER), 0); // prescaler to be able to sample 2400-115200 bps (72MHz/2^16=1099<2400bps)
		nvic_enable_irq(NVIC_TIM_IRQ(UART_SOFT_RX_TIMER)); // allow interrupt for timer
		timer_enable_counter(TIM(UART_SOFT_RX_TIMER)); // start timer to generate interrupts for the RX pins
	#endif
	#if defined(UART_SOFT_TX_TIMER)
		rcc_periph_clock_enable(RCC_TIM(UART_SOFT_TX_TIMER)); // enable clock for timer peripheral
		timer_reset(TIM(UART_SOFT_TX_TIMER)); // reset timer state
		timer_set_mode(TIM(UART_SOFT_TX_TIMER), TIM_CR1_CKD_CK_INT, TIM_CR1_CMS_EDGE, TIM_CR1_DIR_UP); // set timer mode, use undivided timer clock, edge alignment (simple count), and count up
		timer_set_prescaler(TIM(UART_SOFT_TX_TIMER), 0); // prescaler to be able to sample 2400-115200 bps (72MHz/2^16=1099<2400bps)
		nvic_enable_irq(NVIC_TIM_IRQ(UART_SOFT_TX_TIMER)); // allow interrupt for timer
	#endif

	return true; // setup completed
}

#if defined(UART_SOFT_RX_TIMER)
void TIM_ISR(UART_SOFT_RX_TIMER)(void)
{
	if (timer_interrupt_source(TIM(UART_SOFT_RX_TIMER),TIM_SR_CC1IF)) { // got a match on compare 1 for RX0
		timer_clear_flag(TIM(UART_SOFT_RX_TIMER),TIM_SR_CC1IF); // clear flag
#if defined(UART_SOFT_RX_PORT0) && defined(UART_SOFT_RX_PIN0)
		led_toggle();
		rx0_byte += ((gpio_get(GPIO(UART_SOFT_RX_PORT0),GPIO(UART_SOFT_RX_PIN0))==0 ? 0 : 1)<<(rx0_bit-1)); // save bit value
		if (rx0_bit<8) { // not the last bit received
			timer_set_oc_value(TIM(UART_SOFT_RX_TIMER),TIM_OC1,timer_get_counter(TIM(UART_SOFT_RX_TIMER))+rcc_ahb_frequency/UART_SOFT_RX_BAUDRATE0); // set timer to next bit
			rx0_bit++; // wait for next bit
		} else { // last bit received
			// save byte
			timer_disable_irq(TIM(UART_SOFT_RX_TIMER),TIM_DIER_CC1IE); // stop_interrupting
			rx0_bit = 0; // next bit should be first bit of next byte
		}
#endif
	}
}
#endif

#if defined(UART_SOFT_TX_TIMER)
void TIM_ISR(UART_SOFT_TX_TIMER)(void)
{
}
#endif

/** central function handling receive signal activity */
static void rx_activity(void)
{
// verify if UART pin state changed
#if defined(UART_SOFT_RX_PORT0) && defined(UART_SOFT_RX_PIN0)
	if (rx0_state!=gpio_get(GPIO(UART_SOFT_RX_PORT0),GPIO(UART_SOFT_RX_PIN0))) { // only do something if state changed
		rx0_state = gpio_get(GPIO(UART_SOFT_RX_PORT0),GPIO(UART_SOFT_RX_PIN0)); // save new state
		if (rx0_bit==0) { // start bit edge detected
			if (rx0_state==0) { // start bit has to be low
				timer_set_oc_value(TIM(UART_SOFT_RX_TIMER),TIM_OC1,timer_get_counter(TIM(UART_SOFT_RX_TIMER))+(rcc_ahb_frequency/UART_SOFT_RX_BAUDRATE0)*1.5); // set timer to sample data bit 0 in 1.5 bits
				timer_clear_flag(TIM(UART_SOFT_RX_TIMER),TIM_SR_CC1IF); // clear flag before enabling interrupt
				timer_enable_irq(TIM(UART_SOFT_RX_TIMER),TIM_DIER_CC1IE);// enable timer IRQ for RX0
				rx0_byte = 0; // reset byte value
				rx0_bit++; // wait for first bit
			}
		} else { // data bit detected
			timer_set_oc_value(TIM(UART_SOFT_RX_TIMER),TIM_OC1,timer_get_counter(TIM(UART_SOFT_RX_TIMER))+(rcc_ahb_frequency/UART_SOFT_RX_BAUDRATE0)/2); // resync timer to half a bit (good for drifting transmission, bad if the line is noisy)
		}
	}
#endif
}

#if (defined(UART_SOFT_RX_PORT0) && defined(UART_SOFT_RX_PIN0) && UART_SOFT_RX_PIN0==0) || (defined(UART_SOFT_RX_PORT1) && defined(UART_SOFT_RX_PIN1) && UART_SOFT_RX_PIN1==0) || (defined(UART_SOFT_RX_PORT2) && defined(UART_SOFT_RX_PIN2) && UART_SOFT_RX_PIN2==0) || (defined(UART_SOFT_RX_PORT3) && defined(UART_SOFT_RX_PIN3) && UART_SOFT_RX_PIN3==0)
void exti0_isr(void)
{
	exti_reset_request(EXTI0); // clear interrupt flag for pin triggers this ISR (pin state will be checked independently)
	rx_activity(); // check which GPIO changed
}
#endif
#if (defined(UART_SOFT_RX_PORT0) && defined(UART_SOFT_RX_PIN0) && UART_SOFT_RX_PIN0==1) || (defined(UART_SOFT_RX_PORT1) && defined(UART_SOFT_RX_PIN1) && UART_SOFT_RX_PIN1==1) || (defined(UART_SOFT_RX_PORT2) && defined(UART_SOFT_RX_PIN2) && UART_SOFT_RX_PIN2==1) || (defined(UART_SOFT_RX_PORT3) && defined(UART_SOFT_RX_PIN3) && UART_SOFT_RX_PIN3==1)
void exti1_isr(void)
{
	exti_reset_request(EXTI1); // clear interrupt flag for pin triggers this ISR (pin state will be checked independently)
	rx_activity(); // check which GPIO changed
}
#endif
#if (defined(UART_SOFT_RX_PORT0) && defined(UART_SOFT_RX_PIN0) && UART_SOFT_RX_PIN0==2) || (defined(UART_SOFT_RX_PORT1) && defined(UART_SOFT_RX_PIN1) && UART_SOFT_RX_PIN1==2) || (defined(UART_SOFT_RX_PORT2) && defined(UART_SOFT_RX_PIN2) && UART_SOFT_RX_PIN2==2) || (defined(UART_SOFT_RX_PORT3) && defined(UART_SOFT_RX_PIN3) && UART_SOFT_RX_PIN3==2)
void exti2_isr(void)
{
	exti_reset_request(EXTI2); // clear interrupt flag for pin triggers this ISR (pin state will be checked independently)
	rx_activity(); // check which GPIO changed
}
#endif
#if (defined(UART_SOFT_RX_PORT0) && defined(UART_SOFT_RX_PIN0) && UART_SOFT_RX_PIN0==3) || (defined(UART_SOFT_RX_PORT1) && defined(UART_SOFT_RX_PIN1) && UART_SOFT_RX_PIN1==3) || (defined(UART_SOFT_RX_PORT2) && defined(UART_SOFT_RX_PIN2) && UART_SOFT_RX_PIN2==3) || (defined(UART_SOFT_RX_PORT3) && defined(UART_SOFT_RX_PIN3) && UART_SOFT_RX_PIN3==3)
void exti3_isr(void)
{
	exti_reset_request(EXTI3); // clear interrupt flag for pin triggers this ISR (pin state will be checked independently)
	rx_activity(); // check which GPIO changed
}
#endif
#if (defined(UART_SOFT_RX_PORT0) && defined(UART_SOFT_RX_PIN0) && UART_SOFT_RX_PIN0==4) || (defined(UART_SOFT_RX_PORT1) && defined(UART_SOFT_RX_PIN1) && UART_SOFT_RX_PIN1==4) || (defined(UART_SOFT_RX_PORT2) && defined(UART_SOFT_RX_PIN2) && UART_SOFT_RX_PIN2==4) || (defined(UART_SOFT_RX_PORT3) && defined(UART_SOFT_RX_PIN3) && UART_SOFT_RX_PIN3==4)
void exti4_isr(void)
{
	exti_reset_request(EXTI4); // clear interrupt flag for pin triggers this ISR (pin state will be checked independently)
	rx_activity(); // check which GPIO changed
}
#endif
#if (defined(UART_SOFT_RX_PORT0) && defined(UART_SOFT_RX_PIN0) && (UART_SOFT_RX_PIN0==5 || UART_SOFT_RX_PIN0==6 || UART_SOFT_RX_PIN0==7 || UART_SOFT_RX_PIN0==8 || UART_SOFT_RX_PIN0==9)) || (defined(UART_SOFT_RX_PORT1) && defined(UART_SOFT_RX_PIN1) && (UART_SOFT_RX_PIN1==5 || UART_SOFT_RX_PIN1==6 || UART_SOFT_RX_PIN1==7 || UART_SOFT_RX_PIN1==8 || UART_SOFT_RX_PIN1==9)) || (defined(UART_SOFT_RX_PORT2) && defined(UART_SOFT_RX_PIN2) && (UART_SOFT_RX_PIN2==5 || UART_SOFT_RX_PIN2==6 || UART_SOFT_RX_PIN2==7 || UART_SOFT_RX_PIN2==8 || UART_SOFT_RX_PIN2==9)) || (defined(UART_SOFT_RX_PORT3) && defined(UART_SOFT_RX_PIN3) && (UART_SOFT_RX_PIN3==5 || UART_SOFT_RX_PIN3==6 || UART_SOFT_RX_PIN3==7 || UART_SOFT_RX_PIN3==8 || UART_SOFT_RX_PIN3==9))
void exti9_5_isr(void)
{
	exti_reset_request(EXTI5|EXTI6|EXTI7|EXTI8|EXTI9); // clear interrupt flag for pin triggers this ISR (pin state will be checked independently)
	rx_activity(); // check which GPIO changed
}
#endif
#if (defined(UART_SOFT_RX_PORT0) && defined(UART_SOFT_RX_PIN0) && (UART_SOFT_RX_PIN0==10 || UART_SOFT_RX_PIN0==11 || UART_SOFT_RX_PIN0==12 || UART_SOFT_RX_PIN0==13 || UART_SOFT_RX_PIN0==14 || UART_SOFT_RX_PIN0==15)) || (defined(UART_SOFT_RX_PORT1) && defined(UART_SOFT_RX_PIN1) && (UART_SOFT_RX_PIN1==10 || UART_SOFT_RX_PIN1==11 || UART_SOFT_RX_PIN1==12 || UART_SOFT_RX_PIN1==13 || UART_SOFT_RX_PIN1==14 || UART_SOFT_RX_PIN1==15)) || (defined(UART_SOFT_RX_PORT2) && defined(UART_SOFT_RX_PIN2) && (UART_SOFT_RX_PIN2==10 || UART_SOFT_RX_PIN2==11 || UART_SOFT_RX_PIN2==12 || UART_SOFT_RX_PIN2==13 || UART_SOFT_RX_PIN2==14 || UART_SOFT_RX_PIN2==15)) || (defined(UART_SOFT_RX_PORT3) && defined(UART_SOFT_RX_PIN3) && (UART_SOFT_RX_PIN3==10 || UART_SOFT_RX_PIN3==11 || UART_SOFT_RX_PIN3==12 || UART_SOFT_RX_PIN3==13 || UART_SOFT_RX_PIN3==14 || UART_SOFT_RX_PIN3==15))
void exti15_10_isr(void)
{
	exti_reset_request(EXTI10|EXTI11|EXTI12|EXTI13|EXTI14|EXTI15); // clear interrupt flag for pin triggers this ISR (pin state will be checked independently)
	rx_activity(); // check which GPIO changed
}
#endif