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96 lines
2.5 KiB
96 lines
2.5 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* arch/sh/boards/dreamcast/rtc.c |
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* |
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* Dreamcast AICA RTC routines. |
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* |
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* Copyright (c) 2001, 2002 M. R. Brown <[email protected]> |
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* Copyright (c) 2002 Paul Mundt <[email protected]> |
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*/ |
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#include <linux/time.h> |
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#include <linux/rtc.h> |
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#include <linux/io.h> |
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#include <linux/platform_device.h> |
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/* The AICA RTC has an Epoch of 1/1/1950, so we must subtract 20 years (in |
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seconds) to get the standard Unix Epoch when getting the time, and add |
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20 years when setting the time. */ |
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#define TWENTY_YEARS ((20 * 365LU + 5) * 86400) |
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/* The AICA RTC is represented by a 32-bit seconds counter stored in 2 16-bit |
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registers.*/ |
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#define AICA_RTC_SECS_H 0xa0710000 |
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#define AICA_RTC_SECS_L 0xa0710004 |
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/** |
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* aica_rtc_gettimeofday - Get the time from the AICA RTC |
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* @dev: the RTC device (ignored) |
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* @tm: pointer to resulting RTC time structure |
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* |
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* Grabs the current RTC seconds counter and adjusts it to the Unix Epoch. |
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*/ |
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static int aica_rtc_gettimeofday(struct device *dev, struct rtc_time *tm) |
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{ |
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unsigned long val1, val2; |
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time64_t t; |
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do { |
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val1 = ((__raw_readl(AICA_RTC_SECS_H) & 0xffff) << 16) | |
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(__raw_readl(AICA_RTC_SECS_L) & 0xffff); |
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val2 = ((__raw_readl(AICA_RTC_SECS_H) & 0xffff) << 16) | |
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(__raw_readl(AICA_RTC_SECS_L) & 0xffff); |
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} while (val1 != val2); |
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/* normalize to 1970..2106 time range */ |
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t = (u32)(val1 - TWENTY_YEARS); |
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rtc_time64_to_tm(t, tm); |
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return 0; |
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} |
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/** |
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* aica_rtc_settimeofday - Set the AICA RTC to the current time |
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* @dev: the RTC device (ignored) |
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* @tm: pointer to new RTC time structure |
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* |
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* Adjusts the given @tv to the AICA Epoch and sets the RTC seconds counter. |
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*/ |
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static int aica_rtc_settimeofday(struct device *dev, struct rtc_time *tm) |
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{ |
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unsigned long val1, val2; |
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time64_t secs = rtc_tm_to_time64(tm); |
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u32 adj = secs + TWENTY_YEARS; |
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do { |
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__raw_writel((adj & 0xffff0000) >> 16, AICA_RTC_SECS_H); |
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__raw_writel((adj & 0xffff), AICA_RTC_SECS_L); |
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val1 = ((__raw_readl(AICA_RTC_SECS_H) & 0xffff) << 16) | |
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(__raw_readl(AICA_RTC_SECS_L) & 0xffff); |
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val2 = ((__raw_readl(AICA_RTC_SECS_H) & 0xffff) << 16) | |
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(__raw_readl(AICA_RTC_SECS_L) & 0xffff); |
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} while (val1 != val2); |
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return 0; |
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} |
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static const struct rtc_class_ops rtc_generic_ops = { |
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.read_time = aica_rtc_gettimeofday, |
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.set_time = aica_rtc_settimeofday, |
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}; |
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static int __init aica_time_init(void) |
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{ |
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struct platform_device *pdev; |
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pdev = platform_device_register_data(NULL, "rtc-generic", -1, |
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&rtc_generic_ops, |
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sizeof(rtc_generic_ops)); |
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return PTR_ERR_OR_ZERO(pdev); |
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} |
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arch_initcall(aica_time_init);
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