1b2441318SGreg Kroah-Hartman // SPDX-License-Identifier: GPL-2.0 2382b4480SRussell King /* 3382b4480SRussell King * arch/arm/mach-footbridge/isa-rtc.c 4382b4480SRussell King * 5382b4480SRussell King * Copyright (C) 1998 Russell King. 6382b4480SRussell King * Copyright (C) 1998 Phil Blundell 7382b4480SRussell King * 8382b4480SRussell King * CATS has a real-time clock, though the evaluation board doesn't. 9382b4480SRussell King * 10382b4480SRussell King * Changelog: 11382b4480SRussell King * 21-Mar-1998 RMK Created 12382b4480SRussell King * 27-Aug-1998 PJB CATS support 13382b4480SRussell King * 28-Dec-1998 APH Made leds optional 14382b4480SRussell King * 20-Jan-1999 RMK Started merge of EBSA285, CATS and NetWinder 15382b4480SRussell King * 16-Mar-1999 RMK More support for EBSA285-like machines with RTCs in 16382b4480SRussell King */ 17382b4480SRussell King 18382b4480SRussell King #define RTC_PORT(x) (0x70+(x)) 19382b4480SRussell King #define RTC_ALWAYS_BCD 0 20382b4480SRussell King 21382b4480SRussell King #include <linux/init.h> 22382b4480SRussell King #include <linux/mc146818rtc.h> 23382b4480SRussell King #include <linux/io.h> 24382b4480SRussell King 25382b4480SRussell King #include "common.h" 26382b4480SRussell King isa_rtc_init(void)27382b4480SRussell Kingvoid __init isa_rtc_init(void) 28382b4480SRussell King { 29382b4480SRussell King int reg_d, reg_b; 30382b4480SRussell King 31382b4480SRussell King /* 32382b4480SRussell King * Probe for the RTC. 33382b4480SRussell King */ 34382b4480SRussell King reg_d = CMOS_READ(RTC_REG_D); 35382b4480SRussell King 36382b4480SRussell King /* 37382b4480SRussell King * make sure the divider is set 38382b4480SRussell King */ 39382b4480SRussell King CMOS_WRITE(RTC_REF_CLCK_32KHZ, RTC_REG_A); 40382b4480SRussell King 41382b4480SRussell King /* 42382b4480SRussell King * Set control reg B 43382b4480SRussell King * (24 hour mode, update enabled) 44382b4480SRussell King */ 45382b4480SRussell King reg_b = CMOS_READ(RTC_REG_B) & 0x7f; 46382b4480SRussell King reg_b |= 2; 47382b4480SRussell King CMOS_WRITE(reg_b, RTC_REG_B); 48382b4480SRussell King 49382b4480SRussell King if ((CMOS_READ(RTC_REG_A) & 0x7f) == RTC_REF_CLCK_32KHZ && 50382b4480SRussell King CMOS_READ(RTC_REG_B) == reg_b) { 51382b4480SRussell King /* 52382b4480SRussell King * We have a RTC. Check the battery 53382b4480SRussell King */ 54382b4480SRussell King if ((reg_d & 0x80) == 0) 55382b4480SRussell King printk(KERN_WARNING "RTC: *** warning: CMOS battery bad\n"); 56382b4480SRussell King } 57382b4480SRussell King } 58