[linux-2.6-block.git] / drivers / rtc / rtc-mc146818-lib.c

// SPDX-License-Identifier: GPL-2.0-only
#include <linux/bcd.h>
#include <linux/delay.h>
#include <linux/export.h>
#include <linux/mc146818rtc.h>

#ifdef CONFIG_ACPI
#include <linux/acpi.h>
#endif

/*
 * Returns true if a clock update is in progress
 */
static inline unsigned char mc146818_is_updating(void)
{
	unsigned char uip;
	unsigned long flags;

	spin_lock_irqsave(&rtc_lock, flags);
	uip = (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP);
	spin_unlock_irqrestore(&rtc_lock, flags);
	return uip;
}

unsigned int mc146818_get_time(struct rtc_time *time)
{
	unsigned char ctrl;
	unsigned long flags;
	unsigned char century = 0;

#ifdef CONFIG_MACH_DECSTATION
	unsigned int real_year;
#endif

	/*
	 * read RTC once any update in progress is done. The update
	 * can take just over 2ms. We wait 20ms. There is no need to
	 * to poll-wait (up to 1s - eeccch) for the falling edge of RTC_UIP.
	 * If you need to know *exactly* when a second has started, enable
	 * periodic update complete interrupts, (via ioctl) and then
	 * immediately read /dev/rtc which will block until you get the IRQ.
	 * Once the read clears, read the RTC time (again via ioctl). Easy.
	 */
	if (mc146818_is_updating())
		mdelay(20);

	/*
	 * Only the values that we read from the RTC are set. We leave
	 * tm_wday, tm_yday and tm_isdst untouched. Even though the
	 * RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated
	 * by the RTC when initially set to a non-zero value.
	 */
	spin_lock_irqsave(&rtc_lock, flags);
	time->tm_sec = CMOS_READ(RTC_SECONDS);
	time->tm_min = CMOS_READ(RTC_MINUTES);
	time->tm_hour = CMOS_READ(RTC_HOURS);
	time->tm_mday = CMOS_READ(RTC_DAY_OF_MONTH);
	time->tm_mon = CMOS_READ(RTC_MONTH);
	time->tm_year = CMOS_READ(RTC_YEAR);
#ifdef CONFIG_MACH_DECSTATION
	real_year = CMOS_READ(RTC_DEC_YEAR);
#endif
#ifdef CONFIG_ACPI
	if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
	    acpi_gbl_FADT.century)
		century = CMOS_READ(acpi_gbl_FADT.century);
#endif
	ctrl = CMOS_READ(RTC_CONTROL);
	spin_unlock_irqrestore(&rtc_lock, flags);

	if (!(ctrl & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
	{
		time->tm_sec = bcd2bin(time->tm_sec);
		time->tm_min = bcd2bin(time->tm_min);
		time->tm_hour = bcd2bin(time->tm_hour);
		time->tm_mday = bcd2bin(time->tm_mday);
		time->tm_mon = bcd2bin(time->tm_mon);
		time->tm_year = bcd2bin(time->tm_year);
		century = bcd2bin(century);
	}

#ifdef CONFIG_MACH_DECSTATION
	time->tm_year += real_year - 72;
#endif

	if (century > 20)
		time->tm_year += (century - 19) * 100;

	/*
	 * Account for differences between how the RTC uses the values
	 * and how they are defined in a struct rtc_time;
	 */
	if (time->tm_year <= 69)
		time->tm_year += 100;

	time->tm_mon--;

	return RTC_24H;
}
EXPORT_SYMBOL_GPL(mc146818_get_time);

/* Set the current date and time in the real time clock. */
int mc146818_set_time(struct rtc_time *time)
{
	unsigned long flags;
	unsigned char mon, day, hrs, min, sec;
	unsigned char save_control, save_freq_select;
	unsigned int yrs;
#ifdef CONFIG_MACH_DECSTATION
	unsigned int real_yrs, leap_yr;
#endif
	unsigned char century = 0;

	yrs = time->tm_year;
	mon = time->tm_mon + 1;   /* tm_mon starts at zero */
	day = time->tm_mday;
	hrs = time->tm_hour;
	min = time->tm_min;
	sec = time->tm_sec;

	if (yrs > 255)	/* They are unsigned */
		return -EINVAL;

	spin_lock_irqsave(&rtc_lock, flags);
#ifdef CONFIG_MACH_DECSTATION
	real_yrs = yrs;
	leap_yr = ((!((yrs + 1900) % 4) && ((yrs + 1900) % 100)) ||
			!((yrs + 1900) % 400));
	yrs = 72;

	/*
	 * We want to keep the year set to 73 until March
	 * for non-leap years, so that Feb, 29th is handled
	 * correctly.
	 */
	if (!leap_yr && mon < 3) {
		real_yrs--;
		yrs = 73;
	}
#endif

#ifdef CONFIG_ACPI
	if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
	    acpi_gbl_FADT.century) {
		century = (yrs + 1900) / 100;
		yrs %= 100;
	}
#endif

	/* These limits and adjustments are independent of
	 * whether the chip is in binary mode or not.
	 */
	if (yrs > 169) {
		spin_unlock_irqrestore(&rtc_lock, flags);
		return -EINVAL;
	}

	if (yrs >= 100)
		yrs -= 100;

	if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY)
	    || RTC_ALWAYS_BCD) {
		sec = bin2bcd(sec);
		min = bin2bcd(min);
		hrs = bin2bcd(hrs);
		day = bin2bcd(day);
		mon = bin2bcd(mon);
		yrs = bin2bcd(yrs);
		century = bin2bcd(century);
	}

	save_control = CMOS_READ(RTC_CONTROL);
	CMOS_WRITE((save_control|RTC_SET), RTC_CONTROL);
	save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
	CMOS_WRITE((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);

#ifdef CONFIG_MACH_DECSTATION
	CMOS_WRITE(real_yrs, RTC_DEC_YEAR);
#endif
	CMOS_WRITE(yrs, RTC_YEAR);
	CMOS_WRITE(mon, RTC_MONTH);
	CMOS_WRITE(day, RTC_DAY_OF_MONTH);
	CMOS_WRITE(hrs, RTC_HOURS);
	CMOS_WRITE(min, RTC_MINUTES);
	CMOS_WRITE(sec, RTC_SECONDS);
#ifdef CONFIG_ACPI
	if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
	    acpi_gbl_FADT.century)
		CMOS_WRITE(century, acpi_gbl_FADT.century);
#endif

	CMOS_WRITE(save_control, RTC_CONTROL);
	CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);

	spin_unlock_irqrestore(&rtc_lock, flags);

	return 0;
}
EXPORT_SYMBOL_GPL(mc146818_set_time);
Commit	Line	Data
457c8996	1	// SPDX-License-Identifier: GPL-2.0-only
d6faca40 AB	2	#include <linux/bcd.h>
	3	#include <linux/delay.h>
	4	#include <linux/export.h>
	5	#include <linux/mc146818rtc.h>
	6
	7	#ifdef CONFIG_ACPI
	8	#include <linux/acpi.h>
	9	#endif
	10
	11	/*
	12	* Returns true if a clock update is in progress
	13	*/
	14	static inline unsigned char mc146818_is_updating(void)
	15	{
	16	unsigned char uip;
	17	unsigned long flags;
	18
	19	spin_lock_irqsave(&rtc_lock, flags);
	20	uip = (CMOS_READ(RTC_FREQ_SELECT) & RTC_UIP);
	21	spin_unlock_irqrestore(&rtc_lock, flags);
	22	return uip;
	23	}
	24
	25	unsigned int mc146818_get_time(struct rtc_time *time)
	26	{
	27	unsigned char ctrl;
	28	unsigned long flags;
	29	unsigned char century = 0;
	30
	31	#ifdef CONFIG_MACH_DECSTATION
	32	unsigned int real_year;
	33	#endif
	34
	35	/*
	36	* read RTC once any update in progress is done. The update
	37	* can take just over 2ms. We wait 20ms. There is no need to
	38	* to poll-wait (up to 1s - eeccch) for the falling edge of RTC_UIP.
	39	* If you need to know exactly when a second has started, enable
	40	* periodic update complete interrupts, (via ioctl) and then
	41	* immediately read /dev/rtc which will block until you get the IRQ.
	42	* Once the read clears, read the RTC time (again via ioctl). Easy.
	43	*/
	44	if (mc146818_is_updating())
	45	mdelay(20);
	46
	47	/*
	48	* Only the values that we read from the RTC are set. We leave
	49	* tm_wday, tm_yday and tm_isdst untouched. Even though the
	50	* RTC has RTC_DAY_OF_WEEK, we ignore it, as it is only updated
	51	* by the RTC when initially set to a non-zero value.
	52	*/
	53	spin_lock_irqsave(&rtc_lock, flags);
	54	time->tm_sec = CMOS_READ(RTC_SECONDS);
	55	time->tm_min = CMOS_READ(RTC_MINUTES);
	56	time->tm_hour = CMOS_READ(RTC_HOURS);
	57	time->tm_mday = CMOS_READ(RTC_DAY_OF_MONTH);
	58	time->tm_mon = CMOS_READ(RTC_MONTH);
	59	time->tm_year = CMOS_READ(RTC_YEAR);
	60	#ifdef CONFIG_MACH_DECSTATION
	61	real_year = CMOS_READ(RTC_DEC_YEAR);
	62	#endif
	63	#ifdef CONFIG_ACPI
	64	if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
	65	acpi_gbl_FADT.century)
66	century = CMOS_READ(acpi_gbl_FADT.century);
67	#endif
68	ctrl = CMOS_READ(RTC_CONTROL);
69	spin_unlock_irqrestore(&rtc_lock, flags);
70
71	if (!(ctrl & RTC_DM_BINARY) \|\| RTC_ALWAYS_BCD)
72	{
73	time->tm_sec = bcd2bin(time->tm_sec);
74	time->tm_min = bcd2bin(time->tm_min);
75	time->tm_hour = bcd2bin(time->tm_hour);
76	time->tm_mday = bcd2bin(time->tm_mday);
77	time->tm_mon = bcd2bin(time->tm_mon);
78	time->tm_year = bcd2bin(time->tm_year);
79	century = bcd2bin(century);
80	}
81
82	#ifdef CONFIG_MACH_DECSTATION
83	time->tm_year += real_year - 72;
84	#endif
85
2a4daadd	86	if (century > 20)
d6faca40 AB	87	time->tm_year += (century - 19) * 100;
	88
	89	/*
	90	* Account for differences between how the RTC uses the values
	91	* and how they are defined in a struct rtc_time;
	92	*/
	93	if (time->tm_year <= 69)
	94	time->tm_year += 100;
	95
	96	time->tm_mon--;
	97
	98	return RTC_24H;
	99	}
	100	EXPORT_SYMBOL_GPL(mc146818_get_time);
	101
	102	/* Set the current date and time in the real time clock. */
	103	int mc146818_set_time(struct rtc_time *time)
	104	{
	105	unsigned long flags;
	106	unsigned char mon, day, hrs, min, sec;
	107	unsigned char save_control, save_freq_select;
	108	unsigned int yrs;
	109	#ifdef CONFIG_MACH_DECSTATION
	110	unsigned int real_yrs, leap_yr;
	111	#endif
	112	unsigned char century = 0;
	113
	114	yrs = time->tm_year;
	115	mon = time->tm_mon + 1; /* tm_mon starts at zero */
	116	day = time->tm_mday;
	117	hrs = time->tm_hour;
	118	min = time->tm_min;
	119	sec = time->tm_sec;
	120
	121	if (yrs > 255) /* They are unsigned */
	122	return -EINVAL;
	123
	124	spin_lock_irqsave(&rtc_lock, flags);
	125	#ifdef CONFIG_MACH_DECSTATION
	126	real_yrs = yrs;
	127	leap_yr = ((!((yrs + 1900) % 4) && ((yrs + 1900) % 100)) \|\|
	128	!((yrs + 1900) % 400));
	129	yrs = 72;
	130
	131	/*
	132	* We want to keep the year set to 73 until March
	133	* for non-leap years, so that Feb, 29th is handled
	134	* correctly.
	135	*/
	136	if (!leap_yr && mon < 3) {
	137	real_yrs--;
	138	yrs = 73;
	139	}
	140	#endif
	141
	142	#ifdef CONFIG_ACPI
	143	if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
	144	acpi_gbl_FADT.century) {
	145	century = (yrs + 1900) / 100;
	146	yrs %= 100;
	147	}
	148	#endif
	149
	150	/* These limits and adjustments are independent of
151	* whether the chip is in binary mode or not.
152	*/
153	if (yrs > 169) {
154	spin_unlock_irqrestore(&rtc_lock, flags);
155	return -EINVAL;
156	}
157
158	if (yrs >= 100)
159	yrs -= 100;
160
161	if (!(CMOS_READ(RTC_CONTROL) & RTC_DM_BINARY)
162	\|\| RTC_ALWAYS_BCD) {
163	sec = bin2bcd(sec);
164	min = bin2bcd(min);
165	hrs = bin2bcd(hrs);
166	day = bin2bcd(day);
167	mon = bin2bcd(mon);
168	yrs = bin2bcd(yrs);
169	century = bin2bcd(century);
170	}
171
172	save_control = CMOS_READ(RTC_CONTROL);
173	CMOS_WRITE((save_control\|RTC_SET), RTC_CONTROL);
174	save_freq_select = CMOS_READ(RTC_FREQ_SELECT);
175	CMOS_WRITE((save_freq_select\|RTC_DIV_RESET2), RTC_FREQ_SELECT);
176
177	#ifdef CONFIG_MACH_DECSTATION
178	CMOS_WRITE(real_yrs, RTC_DEC_YEAR);
179	#endif
180	CMOS_WRITE(yrs, RTC_YEAR);
181	CMOS_WRITE(mon, RTC_MONTH);
182	CMOS_WRITE(day, RTC_DAY_OF_MONTH);
183	CMOS_WRITE(hrs, RTC_HOURS);
184	CMOS_WRITE(min, RTC_MINUTES);
185	CMOS_WRITE(sec, RTC_SECONDS);
186	#ifdef CONFIG_ACPI
187	if (acpi_gbl_FADT.header.revision >= FADT2_REVISION_ID &&
188	acpi_gbl_FADT.century)
189	CMOS_WRITE(century, acpi_gbl_FADT.century);
190	#endif
191
192	CMOS_WRITE(save_control, RTC_CONTROL);
193	CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
194
195	spin_unlock_irqrestore(&rtc_lock, flags);
196
197	return 0;
198	}
199	EXPORT_SYMBOL_GPL(mc146818_set_time);