// SPDX-License-Identifier: GPL-2.0+
/*
 * (C) Copyright 2007
 * Larry Johnson, lrj@acm.org
 *
 * based on rtc/m41t11.c which is ...
 *
 * (C) Copyright 2002
 * Andrew May, Viasat Inc, amay@viasat.com
 */

/*
 * STMicroelectronics M41T60 serial access real-time clock
 */

/* #define DEBUG 1 */

#include <common.h>
#include <command.h>
#include <env.h>
#include <log.h>
#include <rtc.h>
#include <i2c.h>

/*
 * Convert between century and "century bits" (CB1 and CB0).  These routines
 * assume years are in the range 1900 - 2299.
 */

static unsigned char year2cb(unsigned const year)
{
        if (year < 1900 || year >= 2300)
                printf("M41T60 RTC: year %d out of range\n", year);

        return (year / 100) & 0x3;
}

static unsigned cb2year(unsigned const cb)
{
        return 1900 + 100 * ((cb + 1) & 0x3);
}

/*
 * These are simple defines for the chip local to here so they aren't too
 * verbose.  DAY/DATE aren't nice but that is how they are on the data sheet.
 */
#define RTC_SEC         0x0
#define RTC_MIN         0x1
#define RTC_HOUR        0x2
#define RTC_DAY         0x3
#define RTC_DATE        0x4
#define RTC_MONTH       0x5
#define RTC_YEAR        0x6

#define RTC_REG_CNT     7

#define RTC_CTRL        0x7

#if defined(DEBUG)
static void rtc_dump(char const *const label)
{
        uchar data[8];

        if (i2c_read(CONFIG_SYS_I2C_RTC_ADDR, 0, 1, data, sizeof(data))) {
                printf("I2C read failed in rtc_dump()\n");
                return;
        }
        printf("RTC dump %s: %02X-%02X-%02X-%02X-%02X-%02X-%02X-%02X\n",
               label, data[0], data[1], data[2], data[3],
               data[4], data[5], data[6], data[7]);
}
#else
#define rtc_dump(label)
#endif

static uchar *rtc_validate(void)
{
        /*
         * This routine uses the OUT bit and the validity of the time values to
         * determine whether there has been an initial power-up since the last
         * time the routine was run.  It assumes that the OUT bit is not being
         * used for any other purpose.
         */
        static const uchar daysInMonth[0x13] = {
                0x00, 0x31, 0x29, 0x31, 0x30, 0x31, 0x30, 0x31,
                0x31, 0x30, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
                0x31, 0x30, 0x31
        };
        static uchar data[8];
        uchar min, date, month, years;

        rtc_dump("begin validate");
        if (i2c_read(CONFIG_SYS_I2C_RTC_ADDR, 0, 1, data, sizeof(data))) {
                printf("I2C read failed in rtc_validate()\n");
                return 0;
        }
        /*
         * If the OUT bit is "1", there has been a loss of power, so stop the
         * oscillator so it can be "kick-started" as per data sheet.
         */
        if (0x00 != (data[RTC_CTRL] & 0x80)) {
                printf("M41T60 RTC clock lost power.\n");
                data[RTC_SEC] = 0x80;
                if (i2c_write(CONFIG_SYS_I2C_RTC_ADDR, RTC_SEC, 1, data, 1)) {
                        printf("I2C write failed in rtc_validate()\n");
                        return 0;
                }
        }
        /*
         * If the oscillator is stopped or the date is invalid, then reset the
         * OUT bit to "0", reset the date registers, and start the oscillator.
         */
        min = data[RTC_MIN] & 0x7F;
        date = data[RTC_DATE];
        month = data[RTC_MONTH] & 0x3F;
        years = data[RTC_YEAR];
        if (0x59 < data[RTC_SEC] || 0x09 < (data[RTC_SEC] & 0x0F) ||
            0x59 < min || 0x09 < (min & 0x0F) ||
            0x23 < data[RTC_HOUR] || 0x09 < (data[RTC_HOUR] & 0x0F) ||
            0x07 < data[RTC_DAY] || 0x00 == data[RTC_DAY] ||
            0x12 < month ||
            0x99 < years || 0x09 < (years & 0x0F) ||
            daysInMonth[month] < date || 0x09 < (date & 0x0F) || 0x00 == date ||
            (0x29 == date && 0x02 == month &&
             ((0x00 != (years & 0x03)) ||
              (0x00 == years && 0x00 != (data[RTC_MONTH] & 0xC0))))) {
                printf("Resetting M41T60 RTC clock.\n");
                /*
                 * Set to 00:00:00 1900-01-01 (Monday)
                 */
                data[RTC_SEC] = 0x00;
                data[RTC_MIN] &= 0x80;  /* preserve OFIE bit */
                data[RTC_HOUR] = 0x00;
                data[RTC_DAY] = 0x02;
                data[RTC_DATE] = 0x01;
                data[RTC_MONTH] = 0xC1;
                data[RTC_YEAR] = 0x00;
                data[RTC_CTRL] &= 0x7F; /* reset OUT bit */

                if (i2c_write(CONFIG_SYS_I2C_RTC_ADDR, 0, 1, data, sizeof(data))) {
                        printf("I2C write failed in rtc_validate()\n");
                        return 0;
                }
        }
        return data;
}

int rtc_get(struct rtc_time *tmp)
{
        uchar const *const data = rtc_validate();

        if (!data)
                return -1;

        tmp->tm_sec = bcd2bin(data[RTC_SEC] & 0x7F);
        tmp->tm_min = bcd2bin(data[RTC_MIN] & 0x7F);
        tmp->tm_hour = bcd2bin(data[RTC_HOUR] & 0x3F);
        tmp->tm_mday = bcd2bin(data[RTC_DATE] & 0x3F);
        tmp->tm_mon = bcd2bin(data[RTC_MONTH] & 0x1F);
        tmp->tm_year = cb2year(data[RTC_MONTH] >> 6) + bcd2bin(data[RTC_YEAR]);
        tmp->tm_wday = bcd2bin(data[RTC_DAY] & 0x07) - 1;
        tmp->tm_yday = 0;
        tmp->tm_isdst = 0;

        debug("Get DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
              tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
              tmp->tm_hour, tmp->tm_min, tmp->tm_sec);

        return 0;
}

int rtc_set(struct rtc_time *tmp)
{
        uchar *const data = rtc_validate();

        if (!data)
                return -1;

        debug("Set DATE: %4d-%02d-%02d (wday=%d)  TIME: %2d:%02d:%02d\n",
              tmp->tm_year, tmp->tm_mon, tmp->tm_mday, tmp->tm_wday,
              tmp->tm_hour, tmp->tm_min, tmp->tm_sec);

        data[RTC_SEC] = (data[RTC_SEC] & 0x80) | (bin2bcd(tmp->tm_sec) & 0x7F);
        data[RTC_MIN] = (data[RTC_MIN] & 0X80) | (bin2bcd(tmp->tm_min) & 0X7F);
        data[RTC_HOUR] = bin2bcd(tmp->tm_hour) & 0x3F;
        data[RTC_DATE] = bin2bcd(tmp->tm_mday) & 0x3F;
        data[RTC_MONTH] = bin2bcd(tmp->tm_mon) & 0x1F;
        data[RTC_YEAR] = bin2bcd(tmp->tm_year % 100);
        data[RTC_MONTH] |= year2cb(tmp->tm_year) << 6;
        data[RTC_DAY] = bin2bcd(tmp->tm_wday + 1) & 0x07;
        if (i2c_write(CONFIG_SYS_I2C_RTC_ADDR, 0, 1, data, RTC_REG_CNT)) {
                printf("I2C write failed in rtc_set()\n");
                return -1;
        }

        return 0;
}

void rtc_reset(void)
{
        uchar *const data = rtc_validate();
        char const *const s = env_get("rtccal");

        if (!data)
                return;

        rtc_dump("begin reset");
        /*
         * If environmental variable "rtccal" is present, it must be a hex value
         * between 0x00 and 0x3F, inclusive.  The five least-significan bits
         * represent the calibration magnitude, and the sixth bit the sign bit.
         * If these do not match the contents of the hardware register, that
         * register is updated.  The value 0x00 imples no correction.  Consult
         * the M41T60 documentation for further details.
         */
        if (s) {
                unsigned long const l = hextoul(s, 0);

                if (l <= 0x3F) {
                        if ((data[RTC_CTRL] & 0x3F) != l) {
                                printf("Setting RTC calibration to 0x%02lX\n",
                                       l);
                                data[RTC_CTRL] &= 0xC0;
                                data[RTC_CTRL] |= (uchar) l;
                        }
                } else
                        printf("environment parameter \"rtccal\" not valid: "
                               "ignoring\n");
        }
        /*
         * Turn off frequency test.
         */
        data[RTC_CTRL] &= 0xBF;
        if (i2c_write(CONFIG_SYS_I2C_RTC_ADDR, RTC_CTRL, 1, data + RTC_CTRL, 1)) {
                printf("I2C write failed in rtc_reset()\n");
                return;
        }
        rtc_dump("end reset");
}