// SPDX-License-Identifier: GPL-2.0+
/*
 * (C) Copyright 2009-2012 ADVANSEE
 * Benoît Thébaudeau <benoit.thebaudeau@advansee.com>
 *
 * Based on the Linux rtc-imxdi.c driver, which is:
 * Copyright 2008-2009 Freescale Semiconductor, Inc. All Rights Reserved.
 * Copyright 2010 Orex Computed Radiography
 */

/*
 * Date & Time support for Freescale i.MX DryIce RTC
 */

#include <common.h>
#include <command.h>
#include <linux/compat.h>
#include <rtc.h>
#include <linux/delay.h>

#include <asm/io.h>
#include <asm/arch/imx-regs.h>

/* DryIce Register Definitions */

struct imxdi_regs {
        u32 dtcmr;                      /* Time Counter MSB Reg */
        u32 dtclr;                      /* Time Counter LSB Reg */
        u32 dcamr;                      /* Clock Alarm MSB Reg */
        u32 dcalr;                      /* Clock Alarm LSB Reg */
        u32 dcr;                        /* Control Reg */
        u32 dsr;                        /* Status Reg */
        u32 dier;                       /* Interrupt Enable Reg */
};

#define DCAMR_UNSET     0xFFFFFFFF      /* doomsday - 1 sec */

#define DCR_TCE         (1 << 3)        /* Time Counter Enable */

#define DSR_WBF         (1 << 10)       /* Write Busy Flag */
#define DSR_WNF         (1 << 9)        /* Write Next Flag */
#define DSR_WCF         (1 << 8)        /* Write Complete Flag */
#define DSR_WEF         (1 << 7)        /* Write Error Flag */
#define DSR_CAF         (1 << 4)        /* Clock Alarm Flag */
#define DSR_NVF         (1 << 1)        /* Non-Valid Flag */
#define DSR_SVF         (1 << 0)        /* Security Violation Flag */

#define DIER_WNIE       (1 << 9)        /* Write Next Interrupt Enable */
#define DIER_WCIE       (1 << 8)        /* Write Complete Interrupt Enable */
#define DIER_WEIE       (1 << 7)        /* Write Error Interrupt Enable */
#define DIER_CAIE       (1 << 4)        /* Clock Alarm Interrupt Enable */

/* Driver Private Data */

struct imxdi_data {
        struct imxdi_regs __iomem       *regs;
        int                             init_done;
};

static struct imxdi_data data;

/*
 * This function attempts to clear the dryice write-error flag.
 *
 * A dryice write error is similar to a bus fault and should not occur in
 * normal operation.  Clearing the flag requires another write, so the root
 * cause of the problem may need to be fixed before the flag can be cleared.
 */
static void clear_write_error(void)
{
        int cnt;

        puts("### Warning: RTC - Register write error!\n");

        /* clear the write error flag */
        __raw_writel(DSR_WEF, &data.regs->dsr);

        /* wait for it to take effect */
        for (cnt = 0; cnt < 1000; cnt++) {
                if ((__raw_readl(&data.regs->dsr) & DSR_WEF) == 0)
                        return;
                udelay(10);
        }
        puts("### Error: RTC - Cannot clear write-error flag!\n");
}

/*
 * Write a dryice register and wait until it completes.
 *
 * Use interrupt flags to determine when the write has completed.
 */
#define DI_WRITE_WAIT(val, reg)                                         \
(                                                                       \
        /* do the register write */                                     \
        __raw_writel((val), &data.regs->reg),                           \
                                                                        \
        di_write_wait((val), #reg)                                      \
)
static int di_write_wait(u32 val, const char *reg)
{
        int cnt;
        int ret = 0;
        int rc = 0;

        /* wait for the write to finish */
        for (cnt = 0; cnt < 100; cnt++) {
                if ((__raw_readl(&data.regs->dsr) & (DSR_WCF | DSR_WEF)) != 0) {
                        ret = 1;
                        break;
                }
                udelay(10);
        }
        if (ret == 0)
                printf("### Warning: RTC - Write-wait timeout "
                                "val = 0x%.8x reg = %s\n", val, reg);

        /* check for write error */
        if (__raw_readl(&data.regs->dsr) & DSR_WEF) {
                clear_write_error();
                rc = -1;
        }

        return rc;
}

/*
 * Initialize dryice hardware
 */
static int di_init(void)
{
        int rc = 0;

        data.regs = (struct imxdi_regs __iomem *)IMX_DRYICE_BASE;

        /* mask all interrupts */
        __raw_writel(0, &data.regs->dier);

        /* put dryice into valid state */
        if (__raw_readl(&data.regs->dsr) & DSR_NVF) {
                rc = DI_WRITE_WAIT(DSR_NVF | DSR_SVF, dsr);
                if (rc)
                        goto err;
        }

        /* initialize alarm */
        rc = DI_WRITE_WAIT(DCAMR_UNSET, dcamr);
        if (rc)
                goto err;
        rc = DI_WRITE_WAIT(0, dcalr);
        if (rc)
                goto err;

        /* clear alarm flag */
        if (__raw_readl(&data.regs->dsr) & DSR_CAF) {
                rc = DI_WRITE_WAIT(DSR_CAF, dsr);
                if (rc)
                        goto err;
        }

        /* the timer won't count if it has never been written to */
        if (__raw_readl(&data.regs->dtcmr) == 0) {
                rc = DI_WRITE_WAIT(0, dtcmr);
                if (rc)
                        goto err;
        }

        /* start keeping time */
        if (!(__raw_readl(&data.regs->dcr) & DCR_TCE)) {
                rc = DI_WRITE_WAIT(__raw_readl(&data.regs->dcr) | DCR_TCE, dcr);
                if (rc)
                        goto err;
        }

        data.init_done = 1;
        return 0;

err:
        return rc;
}

int rtc_get(struct rtc_time *tmp)
{
        unsigned long now;
        int rc = 0;

        if (!data.init_done) {
                rc = di_init();
                if (rc)
                        goto err;
        }

        now = __raw_readl(&data.regs->dtcmr);
        rtc_to_tm(now, tmp);

err:
        return rc;
}

int rtc_set(struct rtc_time *tmp)
{
        unsigned long now;
        int rc;

        if (!data.init_done) {
                rc = di_init();
                if (rc)
                        goto err;
        }

        now = rtc_mktime(tmp);
        /* zero the fractional part first */
        rc = DI_WRITE_WAIT(0, dtclr);
        if (rc == 0)
                rc = DI_WRITE_WAIT(now, dtcmr);

err:
        return rc;
}

void rtc_reset(void)
{
        di_init();
}