]> Git Repo - linux.git/blob - arch/arm/mach-footbridge/isa-rtc.c
Merge tag 'amd-drm-next-6.5-2023-06-09' of https://gitlab.freedesktop.org/agd5f/linux...
[linux.git] / arch / arm / mach-footbridge / isa-rtc.c
1 // SPDX-License-Identifier: GPL-2.0
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/io.h>
24
25 #include "common.h"
26
27 void __init isa_rtc_init(void)
28 {
29         int reg_d, reg_b;
30
31         /*
32          * Probe for the RTC.
33          */
34         reg_d = CMOS_READ(RTC_REG_D);
35
36         /*
37          * make sure the divider is set
38          */
39         CMOS_WRITE(RTC_REF_CLCK_32KHZ, RTC_REG_A);
40
41         /*
42          * Set control reg B
43          *   (24 hour mode, update enabled)
44          */
45         reg_b = CMOS_READ(RTC_REG_B) & 0x7f;
46         reg_b |= 2;
47         CMOS_WRITE(reg_b, RTC_REG_B);
48
49         if ((CMOS_READ(RTC_REG_A) & 0x7f) == RTC_REF_CLCK_32KHZ &&
50             CMOS_READ(RTC_REG_B) == reg_b) {
51                 /*
52                  * We have a RTC.  Check the battery
53                  */
54                 if ((reg_d & 0x80) == 0)
55                         printk(KERN_WARNING "RTC: *** warning: CMOS battery bad\n");
56         }
57 }
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