// SPDX-License-Identifier: GPL-2.0
/*
 *  arch/arm/mach-footbridge/isa-rtc.c
 *
 *  Copyright (C) 1998 Russell King.
 *  Copyright (C) 1998 Phil Blundell
 *
 * CATS has a real-time clock, though the evaluation board doesn't.
 *
 * Changelog:
 *  21-Mar-1998 RMK     Created
 *  27-Aug-1998 PJB     CATS support
 *  28-Dec-1998 APH     Made leds optional
 *  20-Jan-1999 RMK     Started merge of EBSA285, CATS and NetWinder
 *  16-Mar-1999 RMK     More support for EBSA285-like machines with RTCs in
 */

#define RTC_PORT(x)             (0x70+(x))
#define RTC_ALWAYS_BCD          0

#include <linux/init.h>
#include <linux/mc146818rtc.h>
#include <linux/io.h>

#include "common.h"

void __init isa_rtc_init(void)
{
        int reg_d, reg_b;

        /*
         * Probe for the RTC.
         */
        reg_d = CMOS_READ(RTC_REG_D);

        /*
         * make sure the divider is set
         */
        CMOS_WRITE(RTC_REF_CLCK_32KHZ, RTC_REG_A);

        /*
         * Set control reg B
         *   (24 hour mode, update enabled)
         */
        reg_b = CMOS_READ(RTC_REG_B) & 0x7f;
        reg_b |= 2;
        CMOS_WRITE(reg_b, RTC_REG_B);

        if ((CMOS_READ(RTC_REG_A) & 0x7f) == RTC_REF_CLCK_32KHZ &&
            CMOS_READ(RTC_REG_B) == reg_b) {
                /*
                 * We have a RTC.  Check the battery
                 */
                if ((reg_d & 0x80) == 0)
                        printk(KERN_WARNING "RTC: *** warning: CMOS battery bad\n");
        }
}