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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
382b4480 RK |
2 | /* |
3 | * arch/arm/mach-footbridge/isa-rtc.c | |
4 | * | |
5 | * Copyright (C) 1998 Russell King. | |
6 | * Copyright (C) 1998 Phil Blundell | |
7 | * | |
8 | * CATS has a real-time clock, though the evaluation board doesn't. | |
9 | * | |
10 | * Changelog: | |
11 | * 21-Mar-1998 RMK Created | |
12 | * 27-Aug-1998 PJB CATS support | |
13 | * 28-Dec-1998 APH Made leds optional | |
14 | * 20-Jan-1999 RMK Started merge of EBSA285, CATS and NetWinder | |
15 | * 16-Mar-1999 RMK More support for EBSA285-like machines with RTCs in | |
16 | */ | |
17 | ||
18 | #define RTC_PORT(x) (0x70+(x)) | |
19 | #define RTC_ALWAYS_BCD 0 | |
20 | ||
21 | #include <linux/init.h> | |
22 | #include <linux/mc146818rtc.h> | |
23 | #include <linux/bcd.h> | |
24 | #include <linux/io.h> | |
25 | ||
26 | #include "common.h" | |
27 | ||
28 | void __init isa_rtc_init(void) | |
29 | { | |
30 | int reg_d, reg_b; | |
31 | ||
32 | /* | |
33 | * Probe for the RTC. | |
34 | */ | |
35 | reg_d = CMOS_READ(RTC_REG_D); | |
36 | ||
37 | /* | |
38 | * make sure the divider is set | |
39 | */ | |
40 | CMOS_WRITE(RTC_REF_CLCK_32KHZ, RTC_REG_A); | |
41 | ||
42 | /* | |
43 | * Set control reg B | |
44 | * (24 hour mode, update enabled) | |
45 | */ | |
46 | reg_b = CMOS_READ(RTC_REG_B) & 0x7f; | |
47 | reg_b |= 2; | |
48 | CMOS_WRITE(reg_b, RTC_REG_B); | |
49 | ||
50 | if ((CMOS_READ(RTC_REG_A) & 0x7f) == RTC_REF_CLCK_32KHZ && | |
51 | CMOS_READ(RTC_REG_B) == reg_b) { | |
52 | /* | |
53 | * We have a RTC. Check the battery | |
54 | */ | |
55 | if ((reg_d & 0x80) == 0) | |
56 | printk(KERN_WARNING "RTC: *** warning: CMOS battery bad\n"); | |
57 | } | |
58 | } |