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/*
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 * PMIC Real Time Clock driver for Nintendo Switch's MAX77620-RTC
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 *
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 * Copyright (c) 2018-2022 CTCaer
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 * Copyright (c) 2019 shchmue
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 *
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 * This program is free software; you can redistribute it and/or modify it
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 * under the terms and conditions of the GNU General Public License,
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 * version 2, as published by the Free Software Foundation.
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 *
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 * This program is distributed in the hope it will be useful, but WITHOUT
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
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 * more details.
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 *
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 * You should have received a copy of the GNU General Public License
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 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
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 */
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#include <rtc/max77620-rtc.h>
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#include <soc/i2c.h>
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#include <soc/pmc.h>
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#include <soc/timer.h>
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#include <soc/t210.h>
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int epoch_offset = 0;
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void max77620_rtc_prep_read()
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{
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	i2c_send_byte(I2C_5, MAX77620_RTC_I2C_ADDR, MAX77620_RTC_UPDATE0_REG, MAX77620_RTC_READ_UPDATE);
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}
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void max77620_rtc_get_time(rtc_time_t *time)
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{
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	u8 val = 0;
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	// Update RTC regs from RTC clock.
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	i2c_send_byte(I2C_5, MAX77620_RTC_I2C_ADDR, MAX77620_RTC_UPDATE0_REG, MAX77620_RTC_READ_UPDATE);
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	// Get control reg config.
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	val = i2c_recv_byte(I2C_5, MAX77620_RTC_I2C_ADDR, MAX77620_RTC_CONTROL_REG);
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	// TODO: Check for binary format also?
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	// Get time.
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	time->sec  = i2c_recv_byte(I2C_5, MAX77620_RTC_I2C_ADDR, MAX77620_RTC_SEC_REG) & 0x7F;
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	time->min  = i2c_recv_byte(I2C_5, MAX77620_RTC_I2C_ADDR, MAX77620_RTC_MIN_REG) & 0x7F;
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	u8 hour    = i2c_recv_byte(I2C_5, MAX77620_RTC_I2C_ADDR, MAX77620_RTC_HOUR_REG);
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	time->hour = hour & 0x1F;
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	if (!(val & MAX77620_RTC_24H) && (hour & MAX77620_RTC_HOUR_PM_MASK))
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		time->hour = (time->hour & 0xF) + 12;
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	// Get day of week. 1: Monday to 7: Sunday.
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	time->weekday = 0;
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	val = i2c_recv_byte(I2C_5, MAX77620_RTC_I2C_ADDR, MAX77620_RTC_WEEKDAY_REG);
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	for (int i = 0; i < 8; i++)
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	{
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		time->weekday++;
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		if (val & 1)
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			break;
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		val >>= 1;
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	}
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	// Get date.
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	time->day   = i2c_recv_byte(I2C_5, MAX77620_RTC_I2C_ADDR, MAX77620_RTC_DATE_REG) & 0x1f;
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	time->month = (i2c_recv_byte(I2C_5, MAX77620_RTC_I2C_ADDR, MAX77620_RTC_MONTH_REG) & 0xF) - 1;
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	time->year  = (i2c_recv_byte(I2C_5, MAX77620_RTC_I2C_ADDR, MAX77620_RTC_YEAR_REG) & 0x7F) + 2000;
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}
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void max77620_rtc_stop_alarm()
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{
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	u8 val = 0;
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	// Update RTC regs from RTC clock.
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	i2c_send_byte(I2C_5, MAX77620_RTC_I2C_ADDR, MAX77620_RTC_UPDATE0_REG, MAX77620_RTC_READ_UPDATE);
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	msleep(16);
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	// Stop alarm for both ALARM1 and ALARM2. Horizon uses ALARM2.
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	for (int i = 0; i < (MAX77620_RTC_NR_TIME_REGS * 2); i++)
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	{
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		val = i2c_recv_byte(I2C_5, MAX77620_RTC_I2C_ADDR, MAX77620_ALARM1_SEC_REG + i);
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		val &= ~MAX77620_RTC_ALARM_EN_MASK;
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		i2c_send_byte(I2C_5, MAX77620_RTC_I2C_ADDR, MAX77620_ALARM1_SEC_REG + i, val);
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	}
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	// Update RTC clock from RTC regs.
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	i2c_send_byte(I2C_5, MAX77620_RTC_I2C_ADDR, MAX77620_RTC_UPDATE0_REG, MAX77620_RTC_WRITE_UPDATE);
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}
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void max77620_rtc_epoch_to_date(u32 epoch, rtc_time_t *time)
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{
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	u32 tmp, edays, year, month, day;
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	// Set time.
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	time->sec  = epoch % 60;
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	epoch /= 60;
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	time->min  = epoch % 60;
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	epoch /= 60;
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	time->hour = epoch % 24;
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	epoch /= 24;
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	// Calculate base date values.
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	tmp = (u32)(((u64)4 * epoch + 102032) / 146097 + 15);
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	tmp = (u32)((u64)epoch + 2442113 + tmp - (tmp >> 2));
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	year = (20 * tmp - 2442) / 7305;
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	edays = tmp - 365 * year - (year >> 2);
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	month = edays * 1000 / 30601;
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	day = edays - month * 30 - month * 601 / 1000;
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	// Month/Year offset.
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	if (month < 14)
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	{
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		year -= 4716;
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		month--;
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	}
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	else
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	{
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		year  -= 4715;
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		month -= 13;
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	}
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	// Set date.
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	time->year = year;
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	time->month = month;
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	time->day = day;
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	// Set weekday.
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	time->weekday = 0; //! TODO.
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}
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u32 max77620_rtc_date_to_epoch(const rtc_time_t *time)
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{
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	u32 year, month, epoch;
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	//Year
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	year = time->year;
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	//Month of year
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	month = time->month;
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	// Month/Year offset.
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	if (month < 3)
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	{
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		month += 12;
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		year--;
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	}
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	epoch  = (365 * year) + (year >> 2) - (year / 100) + (year / 400); // Years to days.
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	epoch += (30 * month) + (3 * (month + 1) / 5) + time->day; // Months to days.
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	epoch -= 719561; // Epoch time is 1/1/1970.
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	epoch *= 86400; // Days to seconds.
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	epoch += (3600 * time->hour) + (60 * time->min) + time->sec; // Add hours, minutes and seconds.
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	return epoch;
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}
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void max77620_rtc_get_time_adjusted(rtc_time_t *time)
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{
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	max77620_rtc_get_time(time);
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	if (epoch_offset)
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	{
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		u32 epoch = (u32)((s64)max77620_rtc_date_to_epoch(time) + epoch_offset);
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		max77620_rtc_epoch_to_date(epoch, time);
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	}
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}
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void max77620_rtc_set_epoch_offset(int offset)
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{
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	epoch_offset = offset;
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}
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void max77620_rtc_set_reboot_reason(rtc_reboot_reason_t *rr)
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{
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	max77620_rtc_stop_alarm();
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	// Set reboot reason.
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	i2c_send_byte(I2C_5, MAX77620_RTC_I2C_ADDR, MAX77620_ALARM1_YEAR_REG, rr->enc.val1);
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	i2c_send_byte(I2C_5, MAX77620_RTC_I2C_ADDR, MAX77620_ALARM2_YEAR_REG, rr->enc.val2);
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	// Set reboot reason magic.
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	i2c_send_byte(I2C_5, MAX77620_RTC_I2C_ADDR, MAX77620_ALARM1_WEEKDAY_REG, RTC_REBOOT_REASON_MAGIC);
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	i2c_send_byte(I2C_5, MAX77620_RTC_I2C_ADDR, MAX77620_ALARM2_WEEKDAY_REG, RTC_REBOOT_REASON_MAGIC);
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	// Update RTC clock from RTC regs.
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	i2c_send_byte(I2C_5, MAX77620_RTC_I2C_ADDR, MAX77620_RTC_UPDATE0_REG, MAX77620_RTC_WRITE_UPDATE);
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	msleep(16);
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}
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bool max77620_rtc_get_reboot_reason(rtc_reboot_reason_t *rr)
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{
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	u8 magic[2];
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	// Get reboot reason magic.
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	magic[0] = i2c_recv_byte(I2C_5, MAX77620_RTC_I2C_ADDR, MAX77620_ALARM1_WEEKDAY_REG);
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	magic[1] = i2c_recv_byte(I2C_5, MAX77620_RTC_I2C_ADDR, MAX77620_ALARM2_WEEKDAY_REG);
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	// Magic must be correct and match on both registers.
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	if (magic[0] != RTC_REBOOT_REASON_MAGIC || magic[0] != magic[1])
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		return false;
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	// Reboot reason setter is expected to have updated the actual regs already.
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	rr->enc.val1 = i2c_recv_byte(I2C_5, MAX77620_RTC_I2C_ADDR, MAX77620_ALARM1_YEAR_REG);
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	rr->enc.val2 = i2c_recv_byte(I2C_5, MAX77620_RTC_I2C_ADDR, MAX77620_ALARM2_YEAR_REG);
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	// Clear magic and update actual regs.
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	i2c_send_byte(I2C_5, MAX77620_RTC_I2C_ADDR, MAX77620_ALARM1_WEEKDAY_REG, 0);
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	i2c_send_byte(I2C_5, MAX77620_RTC_I2C_ADDR, MAX77620_ALARM2_WEEKDAY_REG, 0);
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	i2c_send_byte(I2C_5, MAX77620_RTC_I2C_ADDR, MAX77620_RTC_UPDATE0_REG, MAX77620_RTC_WRITE_UPDATE);
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	// Return reboot reason. False if [config] was selected.
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	return true;
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}
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