From 57f0f512b273f60d52568b8c6b77e17f5636edc0 Mon Sep 17 00:00:00 2001 From: André Fabian Silva Delgado Date: Wed, 5 Aug 2015 17:04:01 -0300 Subject: Initial import --- arch/alpha/kernel/rtc.c | 323 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 323 insertions(+) create mode 100644 arch/alpha/kernel/rtc.c (limited to 'arch/alpha/kernel/rtc.c') diff --git a/arch/alpha/kernel/rtc.c b/arch/alpha/kernel/rtc.c new file mode 100644 index 000000000..f535a3fd0 --- /dev/null +++ b/arch/alpha/kernel/rtc.c @@ -0,0 +1,323 @@ +/* + * linux/arch/alpha/kernel/rtc.c + * + * Copyright (C) 1991, 1992, 1995, 1999, 2000 Linus Torvalds + * + * This file contains date handling. + */ +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include + +#include "proto.h" + + +/* + * Support for the RTC device. + * + * We don't want to use the rtc-cmos driver, because we don't want to support + * alarms, as that would be indistinguishable from timer interrupts. + * + * Further, generic code is really, really tied to a 1900 epoch. This is + * true in __get_rtc_time as well as the users of struct rtc_time e.g. + * rtc_tm_to_time. Thankfully all of the other epochs in use are later + * than 1900, and so it's easy to adjust. + */ + +static unsigned long rtc_epoch; + +static int __init +specifiy_epoch(char *str) +{ + unsigned long epoch = simple_strtoul(str, NULL, 0); + if (epoch < 1900) + printk("Ignoring invalid user specified epoch %lu\n", epoch); + else + rtc_epoch = epoch; + return 1; +} +__setup("epoch=", specifiy_epoch); + +static void __init +init_rtc_epoch(void) +{ + int epoch, year, ctrl; + + if (rtc_epoch != 0) { + /* The epoch was specified on the command-line. */ + return; + } + + /* Detect the epoch in use on this computer. */ + ctrl = CMOS_READ(RTC_CONTROL); + year = CMOS_READ(RTC_YEAR); + if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD) + year = bcd2bin(year); + + /* PC-like is standard; used for year >= 70 */ + epoch = 1900; + if (year < 20) { + epoch = 2000; + } else if (year >= 20 && year < 48) { + /* NT epoch */ + epoch = 1980; + } else if (year >= 48 && year < 70) { + /* Digital UNIX epoch */ + epoch = 1952; + } + rtc_epoch = epoch; + + printk(KERN_INFO "Using epoch %d for rtc year %d\n", epoch, year); +} + +static int +alpha_rtc_read_time(struct device *dev, struct rtc_time *tm) +{ + __get_rtc_time(tm); + + /* Adjust for non-default epochs. It's easier to depend on the + generic __get_rtc_time and adjust the epoch here than create + a copy of __get_rtc_time with the edits we need. */ + if (rtc_epoch != 1900) { + int year = tm->tm_year; + /* Undo the century adjustment made in __get_rtc_time. */ + if (year >= 100) + year -= 100; + year += rtc_epoch - 1900; + /* Redo the century adjustment with the epoch in place. */ + if (year <= 69) + year += 100; + tm->tm_year = year; + } + + return rtc_valid_tm(tm); +} + +static int +alpha_rtc_set_time(struct device *dev, struct rtc_time *tm) +{ + struct rtc_time xtm; + + if (rtc_epoch != 1900) { + xtm = *tm; + xtm.tm_year -= rtc_epoch - 1900; + tm = &xtm; + } + + return __set_rtc_time(tm); +} + +static int +alpha_rtc_set_mmss(struct device *dev, time64_t nowtime) +{ + int retval = 0; + int real_seconds, real_minutes, cmos_minutes; + unsigned char save_control, save_freq_select; + + /* Note: This code only updates minutes and seconds. Comments + indicate this was to avoid messing with unknown time zones, + and with the epoch nonsense described above. In order for + this to work, the existing clock cannot be off by more than + 15 minutes. + + ??? This choice is may be out of date. The x86 port does + not have problems with timezones, and the epoch processing has + now been fixed in alpha_set_rtc_time. + + In either case, one can always force a full rtc update with + the userland hwclock program, so surely 15 minute accuracy + is no real burden. */ + + /* In order to set the CMOS clock precisely, we have to be called + 500 ms after the second nowtime has started, because when + nowtime is written into the registers of the CMOS clock, it will + jump to the next second precisely 500 ms later. Check the Motorola + MC146818A or Dallas DS12887 data sheet for details. */ + + /* irq are locally disabled here */ + spin_lock(&rtc_lock); + /* Tell the clock it's being set */ + save_control = CMOS_READ(RTC_CONTROL); + CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL); + + /* Stop and reset prescaler */ + save_freq_select = CMOS_READ(RTC_FREQ_SELECT); + CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT); + + cmos_minutes = CMOS_READ(RTC_MINUTES); + if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) + cmos_minutes = bcd2bin(cmos_minutes); + + real_seconds = nowtime % 60; + real_minutes = nowtime / 60; + if (((abs(real_minutes - cmos_minutes) + 15) / 30) & 1) { + /* correct for half hour time zone */ + real_minutes += 30; + } + real_minutes %= 60; + + if (abs(real_minutes - cmos_minutes) < 30) { + if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) { + real_seconds = bin2bcd(real_seconds); + real_minutes = bin2bcd(real_minutes); + } + CMOS_WRITE(real_seconds,RTC_SECONDS); + CMOS_WRITE(real_minutes,RTC_MINUTES); + } else { + printk_once(KERN_NOTICE + "set_rtc_mmss: can't update from %d to %d\n", + cmos_minutes, real_minutes); + retval = -1; + } + + /* The following flags have to be released exactly in this order, + * otherwise the DS12887 (popular MC146818A clone with integrated + * battery and quartz) will not reset the oscillator and will not + * update precisely 500 ms later. You won't find this mentioned in + * the Dallas Semiconductor data sheets, but who believes data + * sheets anyway ... -- Markus Kuhn + */ + CMOS_WRITE(save_control, RTC_CONTROL); + CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT); + spin_unlock(&rtc_lock); + + return retval; +} + +static int +alpha_rtc_ioctl(struct device *dev, unsigned int cmd, unsigned long arg) +{ + switch (cmd) { + case RTC_EPOCH_READ: + return put_user(rtc_epoch, (unsigned long __user *)arg); + case RTC_EPOCH_SET: + if (arg < 1900) + return -EINVAL; + rtc_epoch = arg; + return 0; + default: + return -ENOIOCTLCMD; + } +} + +static const struct rtc_class_ops alpha_rtc_ops = { + .read_time = alpha_rtc_read_time, + .set_time = alpha_rtc_set_time, + .set_mmss64 = alpha_rtc_set_mmss, + .ioctl = alpha_rtc_ioctl, +}; + +/* + * Similarly, except do the actual CMOS access on the boot cpu only. + * This requires marshalling the data across an interprocessor call. + */ + +#if defined(CONFIG_SMP) && \ + (defined(CONFIG_ALPHA_GENERIC) || defined(CONFIG_ALPHA_MARVEL)) +# define HAVE_REMOTE_RTC 1 + +union remote_data { + struct rtc_time *tm; + unsigned long now; + long retval; +}; + +static void +do_remote_read(void *data) +{ + union remote_data *x = data; + x->retval = alpha_rtc_read_time(NULL, x->tm); +} + +static int +remote_read_time(struct device *dev, struct rtc_time *tm) +{ + union remote_data x; + if (smp_processor_id() != boot_cpuid) { + x.tm = tm; + smp_call_function_single(boot_cpuid, do_remote_read, &x, 1); + return x.retval; + } + return alpha_rtc_read_time(NULL, tm); +} + +static void +do_remote_set(void *data) +{ + union remote_data *x = data; + x->retval = alpha_rtc_set_time(NULL, x->tm); +} + +static int +remote_set_time(struct device *dev, struct rtc_time *tm) +{ + union remote_data x; + if (smp_processor_id() != boot_cpuid) { + x.tm = tm; + smp_call_function_single(boot_cpuid, do_remote_set, &x, 1); + return x.retval; + } + return alpha_rtc_set_time(NULL, tm); +} + +static void +do_remote_mmss(void *data) +{ + union remote_data *x = data; + x->retval = alpha_rtc_set_mmss(NULL, x->now); +} + +static int +remote_set_mmss(struct device *dev, time64_t now) +{ + union remote_data x; + if (smp_processor_id() != boot_cpuid) { + x.now = now; + smp_call_function_single(boot_cpuid, do_remote_mmss, &x, 1); + return x.retval; + } + return alpha_rtc_set_mmss(NULL, now); +} + +static const struct rtc_class_ops remote_rtc_ops = { + .read_time = remote_read_time, + .set_time = remote_set_time, + .set_mmss64 = remote_set_mmss, + .ioctl = alpha_rtc_ioctl, +}; +#endif + +static int __init +alpha_rtc_init(void) +{ + const struct rtc_class_ops *ops; + struct platform_device *pdev; + struct rtc_device *rtc; + const char *name; + + init_rtc_epoch(); + name = "rtc-alpha"; + ops = &alpha_rtc_ops; + +#ifdef HAVE_REMOTE_RTC + if (alpha_mv.rtc_boot_cpu_only) + ops = &remote_rtc_ops; +#endif + + pdev = platform_device_register_simple(name, -1, NULL, 0); + rtc = devm_rtc_device_register(&pdev->dev, name, ops, THIS_MODULE); + if (IS_ERR(rtc)) + return PTR_ERR(rtc); + + platform_set_drvdata(pdev, rtc); + return 0; +} +device_initcall(alpha_rtc_init); -- cgit v1.2.3-54-g00ecf