/*
 * pcf8523.c
 *
 *  Created on: Mar 25, 2023
 *      Author: Daniel Peter Chokola
 */


/* Includes */
#include "pcf8523.h"
#include "i2c.h"
#include "time.h"

/* Definitions */
/* I2C addresses */
#define PCF_I2C_W (0xd0)
#define PCF_I2C_R (0xd1)
/* Registers */
#define PCF_REG_CONTROL_1       (0x00)
#define PCF_REG_CONTROL_2       (0x01)
#define PCF_REG_CONTROL_3       (0x02)
#define PCF_REG_SECONDS         (0x03)
#define PCF_REG_MINUTES         (0x04)
#define PCF_REG_HOURS           (0x05)
#define PCF_REG_DAYS            (0x06)
#define PCF_REG_WEEKDAYS        (0x07)
#define PCF_REG_MONTHS          (0x08)
#define PCF_REG_YEARS           (0x09)
#define PCF_REG_MINUTE_ALARM    (0x0A)
#define PCF_REG_HOUR_ALARM      (0x0B)
#define PCF_REG_DAY_ALARM       (0x0C)
#define PCF_REG_WEEKDAY_ALARM   (0x0D)
#define PCF_REG_OFFSET          (0x0E)
#define PCF_REG_TMR_CLKOUT_CTRL (0x0F)
#define PCF_REG_TMR_A_FREQ_CTRL (0x10)
#define PCF_REG_TMR_A_REG       (0x11)
#define PCF_REG_TMR_B_FREQ_CTRL (0x12)
#define PCF_REG_TMR_B_REG       (0x13)
/* Bitmasks */
#define PCF_MASK_CTL1_CAP_SEL (0x80) /* internal oscillator capacitor selection for quartz crystals with a corresponding load capacitance */
#define PCF_MASK_CTL1_STOP    (0x20) /* 0 RTC time circuits running; 1 RTC time circuits frozen */
#define PCF_MASK_CTL1_SR      (0x10) /* 0 no software reset; 1 initiate software reset */
#define PCF_MASK_CTL1_12_24   (0x08) /* 0 24 hour mode is selected; 1 12 hour mode is selected */
#define PCF_MASK_CTL1_SIE     (0x04) /* 0 second interrupt disabled; 1 second interrupt enabled */
#define PCF_MASK_CTL1_AIE     (0x02) /* 0 alarm interrupt disabled; 1 alarm interrupt enabled */
#define PCF_MASK_CTL1_CIE     (0x01) /* 0 no correction interrupt generated; 1 interrupt pulses are generated at every correction cycle */
#define PCF_MASK_CTL2_WTAF    (0x80) /* 0 no watchdog timer A interrupt generated; 1 flag set when watchdog timer A interrupt generated */
#define PCF_MASK_CTL2_CTAF    (0x40) /* 0 no countdown timer A interrupt generated; 1 flag set when countdown timer A interrupt generated */
#define PCF_MASK_CTL2_CTBF    (0x20) /* 0 no countdown timer B interrupt generated; 1 flag set when countdown timer B interrupt generated */
#define PCF_MASK_CTL2_SF      (0x10) /* 0 no second interrupt generated; 1 flag set when second interrupt generated */
#define PCF_MASK_CTL2_AF      (0x08) /* 0 no alarm interrupt generated; 1 flag set when alarm triggered */
#define PCF_MASK_CTL2_WTAIE   (0x04) /* 0 watchdog timer A interrupt is disabled; 1 watchdog timer A interrupt is enabled */
#define PCF_MASK_CTL2_CTAIE   (0x02) /* 0 countdown timer A interrupt is disabled; 1 countdown timer A interrupt is enabled */
#define PCF_MASK_CTL2_CTBIE   (0x01) /* 0 countdown timer B interrupt is disabled; 1 countdown timer B interrupt is enabled */
#define PCF_MASK_CTL3_PM      (0xe0) /* battery switch-over and battery low detection control */
#define PCF_MASK_CTL3_BSF     (0x08) /* 0 no battery switch-over interrupt generated; 1 flag set when battery switch-over occurs */
#define PCF_MASK_CTL3_BLF     (0x04) /* 0 battery status ok; 1 battery status low; flag is read-only */
#define PCF_MASK_CTL3_BSIE    (0x02) /* 0 no interrupt generated from battery switch-over flag, BSF; 1 interrupt generated when BSF is set */
#define PCF_MASK_CTL3_BLIE    (0x01) /* 0 no interrupt generated from battery low flag, BLF; 1 interrupt generated when BLF is set */
#define PCF_CMD_CTL1_RESET    (0x58) /* software reset */
/* Slick Macros */
#define bin2bcd(x) ((x / 10) * 6 + x)
#define bcd2bin(x) (x - ((x >> 4) * 6))
#define return_if_fail(cond) \
	if(!(cond)) { return; }
#define return_val_if_fail(cond, val) \
	if(!(cond)) { return (val); }
#define return_null_if_fail(cond) return_val_if_fail((cond), NULL)

/* Private Variables */

/* Function Prototypes */
static void pcf8253_write_byte(pcf8523_t *pcf8523, uint8_t reg, uint8_t data);
static void pcf8253_read_byte(pcf8523_t *pcf8523, uint8_t reg, uint8_t *data);
static void pcf8253_write(pcf8523_t *pcf8523, uint8_t reg, uint8_t *data, uint16_t len);
static void pcf8253_read(pcf8523_t *pcf8523, uint8_t reg, uint8_t *data, uint16_t len);

/* Function Definitions */
int32_t pcf8523_init(pcf8523_t *pcf8523, I2C_HandleTypeDef *hi2c)
{
	uint8_t tmp;

	return_val_if_fail(pcf8523, -1);
	return_val_if_fail(hi2c, -1);

	pcf8523->hi2c = hi2c;
	/* initiate reset */
	pcf8253_write_byte(pcf8523, PCF_REG_CONTROL_1, PCF_CMD_CTL1_RESET);
	/* check if the device is initialized */
	pcf8253_read_byte(pcf8523, PCF_REG_CONTROL_3, &tmp);
	if((tmp & PCF_MASK_CTL3_PM) == PCF_MASK_CTL3_PM)
	{
		/* the RTC has not been initialized -- initialize it */
		/* FIXME: I don't know how to initialize it. */
		/* turn on battery switchover mode */
		pcf8253_write_byte(pcf8523, PCF_REG_CONTROL_3, 0x00);
	}

	return 0;
}

time_t pcf8523_now(pcf8523_t *pcf8523)
{
	struct tm t = { 0 };
	time_t time;
	uint8_t buf[7];

	return_val_if_fail(pcf8523, -1);

	/* read current time */
	pcf8253_read(pcf8523, PCF_REG_SECONDS, buf, 7);
	t.tm_sec  = bcd2bin(buf[0]);       /* Seconds          [0, 60] */
	t.tm_min  = bcd2bin(buf[1]);       /* Minutes          [0, 59] */
	t.tm_hour = bcd2bin(buf[2]);       /* Hour             [0, 23] */
	t.tm_mday = bcd2bin(buf[3]);       /* Day of the month [1, 31] */
	t.tm_wday = bcd2bin(buf[4]);       /* Month            [0, 11]  (January = 0) */
	t.tm_yday = 0;                     /* Day of the year  [0, 365] (Jan/01 = 0) */
	t.tm_mon  = bcd2bin(buf[5]);       /* Month            [0, 11]  (January = 0) */
	t.tm_year = bcd2bin(buf[6]) + 100; /* Year minus 1900 */
	/* tm_wday and tm_yday are ignored by mktime() */
	time = mktime(&t);

	return time;
}

int32_t pcf8523_set_time_t(pcf8523_t *pcf8523, time_t *time)
{
	struct tm *t;

	return_val_if_fail(pcf8523, -1);
	return_val_if_fail(time, -1);

	t = gmtime(time);

	return pcf8523_set_time(pcf8523, t);
}

int32_t pcf8523_set_time(pcf8523_t *pcf8523, struct tm *t)
{
	uint8_t buf[7];

	return_val_if_fail(pcf8523, -1);
	return_val_if_fail(t, -1);

	buf[0] = bin2bcd(t->tm_sec);
	buf[1] = bin2bcd(t->tm_min);
	buf[2] = bin2bcd(t->tm_hour);
	buf[3] = bin2bcd(t->tm_mday);
	buf[4] = bin2bcd(t->tm_wday);
	buf[5] = bin2bcd(t->tm_mon);
	buf[6] = bin2bcd(t->tm_year % 100);
	pcf8253_write(pcf8523, PCF_REG_SECONDS, buf, 7);

	return 0;
}

static void pcf8253_write_byte(pcf8523_t *pcf8523, uint8_t reg, uint8_t data)
{
	HAL_I2C_Mem_Write(pcf8523->hi2c, PCF_I2C_W, reg, I2C_MEMADD_SIZE_8BIT, &data, 1, 10);
}

static void pcf8253_read_byte(pcf8523_t *pcf8523, uint8_t reg, uint8_t *data)
{
	HAL_I2C_Mem_Read(pcf8523->hi2c, PCF_I2C_R, reg, I2C_MEMADD_SIZE_8BIT, data, 1, 10);
}

static void pcf8253_write(pcf8523_t *pcf8523, uint8_t reg, uint8_t *data, uint16_t len)
{
	HAL_I2C_Mem_Write(pcf8523->hi2c, PCF_I2C_W, reg, I2C_MEMADD_SIZE_8BIT, data, len, 10);
}

static void pcf8253_read(pcf8523_t *pcf8523, uint8_t reg, uint8_t *data, uint16_t len)
{
	HAL_I2C_Mem_Read(pcf8523->hi2c, PCF_I2C_R, reg, I2C_MEMADD_SIZE_8BIT, data, len, 10);
}