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