/* 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 communicate using I2C as master (code)
 *  @file i2c_master.c
 *  @author King Kévin <kingkevin@cuvoodoo.info>
 *  @date 2017
 *  @note peripherals used: I2C @ref i2c_master_i2c, timer @ref i2c_master_timer
 */

/* standard libraries */
#include <stdint.h> // standard integer types
#include <stdio.h> // standard I/O facilities
#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/i2c.h> // I2C library
#include <libopencm3/stm32/timer.h> // timer utilities

#include "global.h" // global utilities
#include "i2c_master.h" // I2C header and definitions

/** @defgroup i2c_master_i2c I2C peripheral used to communicate
 *  @{
 */
#define I2C_MASTER_I2C 2 /**< I2C peripheral */
/** @} */

/** @defgroup i2c_master_timer timer peripheral used for timeouts
 *  @{
 */
#define I2C_MASTER_TIMER 4 /**< timer peripheral */
#define I2C_MASTER_TIMEOUT 4 /**< timeout factor (compared to expected time) */
/** @} */


void i2c_master_setup(bool fast)
{
	// configure I2C peripheral
	rcc_periph_clock_enable(RCC_I2C_SCL_PORT(I2C_MASTER_I2C)); // enable clock for I2C I/O peripheral
	gpio_set(I2C_SCL_PORT(I2C_MASTER_I2C), I2C_SCL_PIN(I2C_MASTER_I2C)); // already put signal high to avoid small pulse
	gpio_set_mode(I2C_SCL_PORT(I2C_MASTER_I2C), GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_ALTFN_OPENDRAIN, I2C_SCL_PIN(I2C_MASTER_I2C)); // setup I2C I/O pins
	rcc_periph_clock_enable(RCC_I2C_SCL_PORT(I2C_MASTER_I2C)); // enable clock for I2C I/O peripheral
	gpio_set(I2C_SDA_PORT(I2C_MASTER_I2C), I2C_SDA_PIN(I2C_MASTER_I2C)); // already put signal high to avoid small pulse
    gpio_set_mode(I2C_SDA_PORT(I2C_MASTER_I2C), GPIO_MODE_OUTPUT_2_MHZ, GPIO_CNF_OUTPUT_ALTFN_OPENDRAIN, I2C_SDA_PIN(I2C_MASTER_I2C)); // setup I2C I/O pins
	rcc_periph_clock_enable(RCC_AFIO); // enable clock for alternate function
	rcc_periph_clock_enable(RCC_I2C(I2C_MASTER_I2C)); // enable clock for I2C peripheral
	i2c_reset(I2C(I2C_MASTER_I2C)); // reset configuration
	i2c_peripheral_disable(I2C(I2C_MASTER_I2C)); // I2C needs to be disable to be configured
	i2c_set_clock_frequency(I2C(I2C_MASTER_I2C), rcc_apb1_frequency/1000000); // configure the peripheral clock to the APB1 freq (where it is connected to)
	if (fast) {
		i2c_set_fast_mode(I2C(I2C_MASTER_I2C));
		i2c_set_ccr(I2C(I2C_MASTER_I2C), rcc_apb1_frequency/(400000*2)); // set Thigh/Tlow to generate frequency of 400 kHz
		i2c_set_trise(I2C(I2C_MASTER_I2C), (300/(1000/(rcc_apb1_frequency/1000000)))+1); // max rise time for 300 kHz is 300 ns
	} else {
		i2c_set_standard_mode(I2C(I2C_MASTER_I2C)); // the DS1307 has a maximum I2C SCL freq if 100 kHz (corresponding to the standard mode)
		i2c_set_ccr(I2C(I2C_MASTER_I2C), rcc_apb1_frequency/(100000*2)); // set Thigh/Tlow to generate frequency of 100 kHz
		i2c_set_trise(I2C(I2C_MASTER_I2C), (1000/(1000/(rcc_apb1_frequency/1000000)))+1); // max rise time for 100 kHz is 1000 ns (~1 MHz)
	}
	i2c_peripheral_enable(I2C(I2C_MASTER_I2C)); // enable I2C after configuration completed

	// configure time for timeouts
	rcc_periph_clock_enable(RCC_TIM(I2C_MASTER_TIMER)); // enable clock for timer block
	timer_reset(TIM(I2C_MASTER_TIMER)); // reset timer state
	timer_set_mode(TIM(I2C_MASTER_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_one_shot_mode(TIM(I2C_MASTER_TIMER)); // stop counter after update event (we only need to one timeout and reset before next operation)
	if (fast) {
		timer_set_prescaler(TIM(I2C_MASTER_TIMER), rcc_ahb_frequency/400000-1); // set the prescaler so one tick is also one I2C bit (used I2C frequency)
	} else {
		timer_set_prescaler(TIM(I2C_MASTER_TIMER), rcc_ahb_frequency/100000-1); // set the prescaler so one tick is also one I2C bit (used I2C frequency)
	}
	timer_set_period(TIM(I2C_MASTER_TIMER), I2C_MASTER_TIMEOUT*9); // use factor to wait for all 9 bits to be transmitted
	timer_update_on_overflow(TIM(I2C_MASTER_TIMER)); // only use counter overflow as UEV source (use overflow as timeout)

	// wait one transaction for the signal to be stable (some slave have issues when an I2C transaction immediately follows)
	timer_set_counter(TIM(I2C_MASTER_TIMER),0); // restart timer
	timer_clear_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF); // clear flag
	timer_enable_counter(TIM(I2C_MASTER_TIMER)); // enable timer for timeouts
	while ( !timer_get_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF));
	timer_disable_counter(TIM(I2C_MASTER_TIMER)); // disable timer for timeouts
	timer_clear_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF); // clear flag
}

bool i2c_master_read(uint8_t slave, const uint8_t* address, size_t address_size, uint8_t* data, size_t data_size)
{
	// sanity check
	if (address==NULL || address_size==0 || data==NULL || data_size==0) { // input data is erroneous
		return false;
	}	
	if (I2C_SR2(I2C(I2C_MASTER_I2C)) & I2C_SR2_BUSY) { // I2C device is busy
		return false;
	}	
	if (I2C_SR2(I2C(I2C_MASTER_I2C)) & I2C_SR2_MSL) { // I2C device is already in master mode
		return false;
	}

	bool to_return = false; // return if read succeeded

	// send start condition
	i2c_send_start(I2C(I2C_MASTER_I2C)); // send start condition to start transaction
	timer_set_counter(TIM(I2C_MASTER_TIMER),0); // restart timer
	timer_clear_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF); // clear flag 
	timer_enable_counter(TIM(I2C_MASTER_TIMER)); // enable timer for timeouts
	while (!(I2C_SR1(I2C(I2C_MASTER_I2C)) & I2C_SR1_SB) && !timer_get_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF)); // wait until start condition is transmitted
	timer_disable_counter(TIM(I2C_MASTER_TIMER)); // disable timer for timeouts
	if (timer_get_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF)) { // timeout occurred
		timer_clear_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF); // clear flag
		goto error;
	}
	if (!(I2C_SR2(I2C(I2C_MASTER_I2C)) & I2C_SR2_MSL)) { // verify if in master mode
		goto error;
	}

	// select slave
	i2c_send_7bit_address(I2C(I2C_MASTER_I2C), slave, I2C_WRITE); // select slave
	timer_set_counter(TIM(I2C_MASTER_TIMER),0); // restart timer
	timer_clear_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF); // clear flag 
	timer_enable_counter(TIM(I2C_MASTER_TIMER)); // enable timer for timeouts
	while (!(I2C_SR1(I2C(I2C_MASTER_I2C)) & I2C_SR1_ADDR) && !timer_get_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF)); // wait until address is transmitted
	timer_disable_counter(TIM(I2C_MASTER_TIMER)); // disable timer for timeouts
	if (timer_get_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF)) { // timeout occurred
		timer_clear_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF); // clear flag
		goto error;
	}
	if (!((I2C_SR2(I2C(I2C_MASTER_I2C)) & I2C_SR2_TRA))) { // verify we are in transmit mode (and read SR2 to clear ADDR)
		goto error;
	}

	// send address
	for (size_t i=0; i<address_size; i++) {
		i2c_send_data(I2C(I2C_MASTER_I2C), address[i]); // send memory address we want to read
		timer_set_counter(TIM(I2C_MASTER_TIMER),0); // restart timer
		timer_clear_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF); // clear flag 
		timer_enable_counter(TIM(I2C_MASTER_TIMER)); // enable timer for timeouts
		while (!(I2C_SR1(I2C(I2C_MASTER_I2C)) & I2C_SR1_TxE) && !timer_get_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF)); // wait until byte has been transmitted
		timer_disable_counter(TIM(I2C_MASTER_TIMER)); // disable timer for timeouts
		if (timer_get_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF)) { // timeout occurred
			timer_clear_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF); // clear flag
			goto error;
		}
	}

	// switch to read mode
	i2c_send_start(I2C(I2C_MASTER_I2C)); // send restart condition to switch from write to read mode
	timer_set_counter(TIM(I2C_MASTER_TIMER),0); // restart timer
	timer_clear_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF); // clear flag 
	timer_enable_counter(TIM(I2C_MASTER_TIMER)); // enable timer for timeouts
	while (!(I2C_SR1(I2C(I2C_MASTER_I2C)) & I2C_SR1_SB) && !timer_get_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF)); // wait until start condition is transmitted
	timer_disable_counter(TIM(I2C_MASTER_TIMER)); // disable timer for timeouts
	if (timer_get_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF)) { // timeout occurred
		timer_clear_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF); // clear flag
		goto error;
	}

	i2c_send_7bit_address(I2C(I2C_MASTER_I2C), slave, I2C_READ); // select slave
	timer_set_counter(TIM(I2C_MASTER_TIMER),0); // restart timer
	timer_clear_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF); // clear flag 
	timer_enable_counter(TIM(I2C_MASTER_TIMER)); // enable timer for timeouts
	while (!(I2C_SR1(I2C(I2C_MASTER_I2C)) & I2C_SR1_ADDR) && !timer_get_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF)); // wait until address is transmitted
	timer_disable_counter(TIM(I2C_MASTER_TIMER)); // disable timer for timeouts
	if (timer_get_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF)) { // timeout occurred
		timer_clear_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF); // clear flag
		goto error;
	}
	if ((I2C_SR2(I2C(I2C_MASTER_I2C)) & I2C_SR2_TRA)) { // verify we are in read mode (and read SR2 to clear ADDR)
		goto error;
	}

	// read data
	for (size_t i=0; i<data_size; i++) { // read bytes
		if (i==data_size-1) { // prepare to sent NACK for last byte
			i2c_disable_ack(I2C(I2C_MASTER_I2C)); // NACK received to stop slave transmission
			i2c_send_stop(I2C(I2C_MASTER_I2C)); // send STOP after receiving byte
		} else {
			i2c_enable_ack(I2C(I2C_MASTER_I2C)); // ACK received byte to continue slave transmission
		}
		timer_set_counter(TIM(I2C_MASTER_TIMER),0); // restart timer
		timer_clear_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF); // clear flag 
		timer_enable_counter(TIM(I2C_MASTER_TIMER)); // enable timer for timeouts
		while (!(I2C_SR1(I2C(I2C_MASTER_I2C)) & I2C_SR1_RxNE) && !timer_get_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF)); // wait until byte has been received
		timer_disable_counter(TIM(I2C_MASTER_TIMER)); // disable timer for timeouts
		if (timer_get_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF)) { // timeout occurred
			timer_clear_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF); // clear flag
			goto error;
		}
		data[i] = i2c_get_data(I2C(I2C_MASTER_I2C)); // read received byte
	}
	to_return = true;

error:
	if (I2C_SR2(I2C(I2C_MASTER_I2C)) & I2C_SR2_BUSY) { // release bus if busy
//		i2c_send_stop(I2C(I2C_MASTER_I2C)); // send stop to release bus
	}
	i2c_send_stop(I2C(I2C_MASTER_I2C)); // send stop to release bus
	timer_set_counter(TIM(I2C_MASTER_TIMER),0); // restart timer
	timer_clear_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF); // clear flag 
	timer_enable_counter(TIM(I2C_MASTER_TIMER)); // enable timer for timeouts
	while ((I2C_SR2(I2C(I2C_MASTER_I2C)) & I2C_SR2_MSL) && !timer_get_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF)); // wait until bus released (non master mode)
	timer_disable_counter(TIM(I2C_MASTER_TIMER)); // disable timer for timeouts
	if (timer_get_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF)) { // timeout occurred
		timer_clear_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF); // clear flag
	}
	return to_return;
}

bool i2c_master_write(uint8_t slave, const uint8_t* address, size_t address_size, const uint8_t* data, size_t data_size)
{
	// sanity check
	if (address==NULL || address_size==0 || data==NULL || data_size==0) { // input data is erroneous
		return false;
	}	
	if (I2C_SR2(I2C(I2C_MASTER_I2C)) & I2C_SR2_BUSY) { // I2C device is busy
		return false;
	}	
	if (I2C_SR2(I2C(I2C_MASTER_I2C)) & I2C_SR2_MSL) { // I2C device is already in master mode
		return false;
	}

	bool to_return = false; // return if read succeeded

	// send start condition
	i2c_send_start(I2C(I2C_MASTER_I2C)); // send start condition to start transaction
	
	timer_set_counter(TIM(I2C_MASTER_TIMER),0); // restart timer
	timer_clear_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF); // clear flag 
	timer_enable_counter(TIM(I2C_MASTER_TIMER)); // enable timer for timeouts
	while (!(I2C_SR1(I2C(I2C_MASTER_I2C)) & I2C_SR1_SB) && !timer_get_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF)); // wait until start condition is transmitted
	timer_disable_counter(TIM(I2C_MASTER_TIMER)); // disable timer for timeouts
	if (timer_get_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF)) { // timeout occurred
		timer_clear_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF); // clear flag
		goto error;
	}

	if (!(I2C_SR2(I2C(I2C_MASTER_I2C)) & I2C_SR2_MSL)) { // verify if in master mode
		goto error;
	}

	// select slave
	i2c_send_7bit_address(I2C(I2C_MASTER_I2C), slave, I2C_WRITE); // select slave
	timer_set_counter(TIM(I2C_MASTER_TIMER),0); // restart timer
	timer_clear_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF); // clear flag 
	timer_enable_counter(TIM(I2C_MASTER_TIMER)); // enable timer for timeouts
	while (!(I2C_SR1(I2C(I2C_MASTER_I2C)) & I2C_SR1_ADDR) && !timer_get_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF)); // wait until address is transmitted
	timer_disable_counter(TIM(I2C_MASTER_TIMER)); // disable timer for timeouts
	if (timer_get_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF)) { // timeout occurred
		timer_clear_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF); // clear flag
		goto error;
	}
	if (!((I2C_SR2(I2C(I2C_MASTER_I2C)) & I2C_SR2_TRA))) { // verify we are in transmit mode (and read SR2 to clear ADDR)
		goto error;
	}

	// send address
	for (size_t i=0; i<address_size; i++) {
		i2c_send_data(I2C(I2C_MASTER_I2C), address[i]); // send memory address we want to read
		timer_set_counter(TIM(I2C_MASTER_TIMER),0); // restart timer
		timer_clear_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF); // clear flag 
		timer_enable_counter(TIM(I2C_MASTER_TIMER)); // enable timer for timeouts
		while (!(I2C_SR1(I2C(I2C_MASTER_I2C)) & I2C_SR1_TxE) && !timer_get_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF)); // wait until byte has been transmitted
		timer_disable_counter(TIM(I2C_MASTER_TIMER)); // disable timer for timeouts
		if (timer_get_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF)) { // timeout occurred
			timer_clear_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF); // clear flag
			goto error;
		}
	}

	// write data
	for (size_t i=0; i<data_size; i++) { // write bytes
		i2c_send_data(I2C(I2C_MASTER_I2C), data[i]); // send byte to be written in memory
		timer_set_counter(TIM(I2C_MASTER_TIMER),0); // restart timer
		timer_clear_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF); // clear flag 
		timer_enable_counter(TIM(I2C_MASTER_TIMER)); // enable timer for timeouts
		while (!(I2C_SR1(I2C(I2C_MASTER_I2C)) & I2C_SR1_TxE) && !timer_get_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF)); // wait until byte has been transmitted
		timer_disable_counter(TIM(I2C_MASTER_TIMER)); // disable timer for timeouts
		if (timer_get_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF)) { // timeout occurred
			timer_clear_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF); // clear flag
			goto error;
		}
	}
	to_return = true;

error:
	if (I2C_SR2(I2C(I2C_MASTER_I2C)) & I2C_SR2_BUSY) { // release bus if busy
		i2c_send_stop(I2C(I2C_MASTER_I2C)); // send stop to release bus
	}
	timer_set_counter(TIM(I2C_MASTER_TIMER),0); // restart timer
	timer_clear_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF); // clear flag 
	timer_enable_counter(TIM(I2C_MASTER_TIMER)); // enable timer for timeouts
	while ((I2C_SR2(I2C(I2C_MASTER_I2C)) & I2C_SR2_MSL)  && !timer_get_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF)); // wait until bus released (non master mode)
	timer_disable_counter(TIM(I2C_MASTER_TIMER)); // disable timer for timeouts
	if (timer_get_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF)) { // timeout occurred
		timer_clear_flag(TIM(I2C_MASTER_TIMER), TIM_SR_UIF); // clear flag
	}
	return to_return;
}