// 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/bcd.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"); } }