1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *  (c) Copyright 2004 Benjamin Herrenschmidt (benh@kernel.crashing.org),
4  *                     IBM Corp.
5  */
6 
7 #undef DEBUG
8 
9 #include <linux/errno.h>
10 #include <linux/sched.h>
11 #include <linux/kernel.h>
12 #include <linux/param.h>
13 #include <linux/string.h>
14 #include <linux/mm.h>
15 #include <linux/init.h>
16 #include <linux/time.h>
17 #include <linux/adb.h>
18 #include <linux/pmu.h>
19 #include <linux/interrupt.h>
20 #include <linux/mc146818rtc.h>
21 #include <linux/bcd.h>
22 #include <linux/of_address.h>
23 
24 #include <asm/sections.h>
25 #include <asm/io.h>
26 #include <asm/machdep.h>
27 #include <asm/time.h>
28 
29 #include "maple.h"
30 
31 #ifdef DEBUG
32 #define DBG(x...) printk(x)
33 #else
34 #define DBG(x...)
35 #endif
36 
37 static int maple_rtc_addr;
38 
39 static int maple_clock_read(int addr)
40 {
41 	outb_p(addr, maple_rtc_addr);
42 	return inb_p(maple_rtc_addr+1);
43 }
44 
45 static void maple_clock_write(unsigned long val, int addr)
46 {
47 	outb_p(addr, maple_rtc_addr);
48 	outb_p(val, maple_rtc_addr+1);
49 }
50 
51 void maple_get_rtc_time(struct rtc_time *tm)
52 {
53 	do {
54 		tm->tm_sec = maple_clock_read(RTC_SECONDS);
55 		tm->tm_min = maple_clock_read(RTC_MINUTES);
56 		tm->tm_hour = maple_clock_read(RTC_HOURS);
57 		tm->tm_mday = maple_clock_read(RTC_DAY_OF_MONTH);
58 		tm->tm_mon = maple_clock_read(RTC_MONTH);
59 		tm->tm_year = maple_clock_read(RTC_YEAR);
60 	} while (tm->tm_sec != maple_clock_read(RTC_SECONDS));
61 
62 	if (!(maple_clock_read(RTC_CONTROL) & RTC_DM_BINARY)
63 	    || RTC_ALWAYS_BCD) {
64 		tm->tm_sec = bcd2bin(tm->tm_sec);
65 		tm->tm_min = bcd2bin(tm->tm_min);
66 		tm->tm_hour = bcd2bin(tm->tm_hour);
67 		tm->tm_mday = bcd2bin(tm->tm_mday);
68 		tm->tm_mon = bcd2bin(tm->tm_mon);
69 		tm->tm_year = bcd2bin(tm->tm_year);
70 	  }
71 	if ((tm->tm_year + 1900) < 1970)
72 		tm->tm_year += 100;
73 
74 	tm->tm_wday = -1;
75 }
76 
77 int maple_set_rtc_time(struct rtc_time *tm)
78 {
79 	unsigned char save_control, save_freq_select;
80 	int sec, min, hour, mon, mday, year;
81 
82 	spin_lock(&rtc_lock);
83 
84 	save_control = maple_clock_read(RTC_CONTROL); /* tell the clock it's being set */
85 
86 	maple_clock_write((save_control|RTC_SET), RTC_CONTROL);
87 
88 	save_freq_select = maple_clock_read(RTC_FREQ_SELECT); /* stop and reset prescaler */
89 
90 	maple_clock_write((save_freq_select|RTC_DIV_RESET2), RTC_FREQ_SELECT);
91 
92 	sec = tm->tm_sec;
93 	min = tm->tm_min;
94 	hour = tm->tm_hour;
95 	mon = tm->tm_mon;
96 	mday = tm->tm_mday;
97 	year = tm->tm_year;
98 
99 	if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
100 		sec = bin2bcd(sec);
101 		min = bin2bcd(min);
102 		hour = bin2bcd(hour);
103 		mon = bin2bcd(mon);
104 		mday = bin2bcd(mday);
105 		year = bin2bcd(year);
106 	}
107 	maple_clock_write(sec, RTC_SECONDS);
108 	maple_clock_write(min, RTC_MINUTES);
109 	maple_clock_write(hour, RTC_HOURS);
110 	maple_clock_write(mon, RTC_MONTH);
111 	maple_clock_write(mday, RTC_DAY_OF_MONTH);
112 	maple_clock_write(year, RTC_YEAR);
113 
114 	/* The following flags have to be released exactly in this order,
115 	 * otherwise the DS12887 (popular MC146818A clone with integrated
116 	 * battery and quartz) will not reset the oscillator and will not
117 	 * update precisely 500 ms later. You won't find this mentioned in
118 	 * the Dallas Semiconductor data sheets, but who believes data
119 	 * sheets anyway ...                           -- Markus Kuhn
120 	 */
121 	maple_clock_write(save_control, RTC_CONTROL);
122 	maple_clock_write(save_freq_select, RTC_FREQ_SELECT);
123 
124 	spin_unlock(&rtc_lock);
125 
126 	return 0;
127 }
128 
129 static struct resource rtc_iores = {
130 	.name = "rtc",
131 	.flags = IORESOURCE_IO | IORESOURCE_BUSY,
132 };
133 
134 time64_t __init maple_get_boot_time(void)
135 {
136 	struct rtc_time tm;
137 	struct device_node *rtcs;
138 
139 	rtcs = of_find_compatible_node(NULL, "rtc", "pnpPNP,b00");
140 	if (rtcs) {
141 		struct resource r;
142 		if (of_address_to_resource(rtcs, 0, &r)) {
143 			printk(KERN_EMERG "Maple: Unable to translate RTC"
144 			       " address\n");
145 			goto bail;
146 		}
147 		if (!(r.flags & IORESOURCE_IO)) {
148 			printk(KERN_EMERG "Maple: RTC address isn't PIO!\n");
149 			goto bail;
150 		}
151 		maple_rtc_addr = r.start;
152 		printk(KERN_INFO "Maple: Found RTC at IO 0x%x\n",
153 		       maple_rtc_addr);
154 	}
155  bail:
156 	if (maple_rtc_addr == 0) {
157 		maple_rtc_addr = RTC_PORT(0); /* legacy address */
158 		printk(KERN_INFO "Maple: No device node for RTC, assuming "
159 		       "legacy address (0x%x)\n", maple_rtc_addr);
160 	}
161 
162 	rtc_iores.start = maple_rtc_addr;
163 	rtc_iores.end = maple_rtc_addr + 7;
164 	request_resource(&ioport_resource, &rtc_iores);
165 
166 	maple_get_rtc_time(&tm);
167 	return rtc_tm_to_time64(&tm);
168 }
169 
170