1/*
2 * Copyright 2001 MontaVista Software Inc.
3 * Author: jsun@mvista.com or jsun@junsun.net
4 *
5 * arch/mips/ddb5xxx/common/rtc_ds1386.c
6 *     low-level RTC hookups for s for Dallas 1396 chip.
7 *
8 * This program is free software; you can redistribute  it and/or modify it
9 * under  the terms of  the GNU General  Public License as published by the
10 * Free Software Foundation;  either version 2 of the  License, or (at your
11 * option) any later version.
12 */
13
14
15/*
16 * This file exports a function, rtc_ds1386_init(), which expects an
17 * uncached base address as the argument.  It will set the two function
18 * pointers expected by the MIPS generic timer code.
19 */
20
21#include <linux/types.h>
22#include <linux/time.h>
23
24#include <asm/time.h>
25#include <asm/addrspace.h>
26
27#include <asm/mc146818rtc.h>
28#include <asm/debug.h>
29
30#define	EPOCH		2000
31
32#undef BCD_TO_BIN
33#define BCD_TO_BIN(val) (((val)&15) + ((val)>>4)*10)
34
35#undef BIN_TO_BCD
36#define BIN_TO_BCD(val) ((((val)/10)<<4) + (val)%10)
37
38#define	READ_RTC(x)	*(volatile unsigned char*)(rtc_base+x)
39#define	WRITE_RTC(x, y)	*(volatile unsigned char*)(rtc_base+x) = y
40
41static unsigned long rtc_base;
42
43static unsigned long
44rtc_ds1386_get_time(void)
45{
46	u8 byte;
47	u8 temp;
48	unsigned int year, month, day, hour, minute, second;
49
50	/* let us freeze external registers */
51	byte = READ_RTC(0xB);
52	byte &= 0x3f;
53	WRITE_RTC(0xB, byte);
54
55	/* read time data */
56	year = BCD_TO_BIN(READ_RTC(0xA)) + EPOCH;
57	month = BCD_TO_BIN(READ_RTC(0x9) & 0x1f);
58	day = BCD_TO_BIN(READ_RTC(0x8));
59	minute = BCD_TO_BIN(READ_RTC(0x2));
60	second = BCD_TO_BIN(READ_RTC(0x1));
61
62	/* hour is special - deal with it later */
63	temp = READ_RTC(0x4);
64
65	/* enable time transfer */
66	byte |= 0x80;
67	WRITE_RTC(0xB, byte);
68
69	/* calc hour */
70	if (temp & 0x40) {
71		/* 12 hour format */
72		hour = BCD_TO_BIN(temp & 0x1f);
73		if (temp & 0x20) hour += 12; 		/* PM */
74	} else {
75		/* 24 hour format */
76		hour = BCD_TO_BIN(temp & 0x3f);
77	}
78
79	return mktime(year, month, day, hour, minute, second);
80}
81
82static int
83rtc_ds1386_set_time(unsigned long t)
84{
85	struct rtc_time tm;
86	u8 byte;
87	u8 temp;
88	u8 year, month, day, hour, minute, second;
89
90	/* let us freeze external registers */
91	byte = READ_RTC(0xB);
92	byte &= 0x3f;
93	WRITE_RTC(0xB, byte);
94
95	/* convert */
96	to_tm(t, &tm);
97
98
99	/* check each field one by one */
100	year = BIN_TO_BCD(tm.tm_year - EPOCH);
101	if (year != READ_RTC(0xA)) {
102		WRITE_RTC(0xA, year);
103	}
104
105	temp = READ_RTC(0x9);
106	month = BIN_TO_BCD(tm.tm_mon+1);	/* tm_mon starts from 0 to 11 */
107	if (month != (temp & 0x1f)) {
108		WRITE_RTC( 0x9,
109			   (month & 0x1f) | (temp & ~0x1f) );
110	}
111
112	day = BIN_TO_BCD(tm.tm_mday);
113	if (day != READ_RTC(0x8)) {
114		WRITE_RTC(0x8, day);
115	}
116
117	temp = READ_RTC(0x4);
118	if (temp & 0x40) {
119		/* 12 hour format */
120		hour = 0x40;
121		if (tm.tm_hour > 12) {
122			hour |= 0x20 | (BIN_TO_BCD(hour-12) & 0x1f);
123		} else {
124			hour |= BIN_TO_BCD(tm.tm_hour);
125		}
126	} else {
127		/* 24 hour format */
128		hour = BIN_TO_BCD(tm.tm_hour) & 0x3f;
129	}
130	if (hour != temp) WRITE_RTC(0x4, hour);
131
132	minute = BIN_TO_BCD(tm.tm_min);
133	if (minute != READ_RTC(0x2)) {
134		WRITE_RTC(0x2, minute);
135	}
136
137	second = BIN_TO_BCD(tm.tm_sec);
138	if (second != READ_RTC(0x1)) {
139		WRITE_RTC(0x1, second);
140	}
141
142	return 0;
143}
144
145void
146rtc_ds1386_init(unsigned long base)
147{
148	unsigned char byte;
149
150	/* remember the base */
151	rtc_base = base;
152	db_assert((rtc_base & 0xe0000000) == KSEG1);
153
154	/* turn on RTC if it is not on */
155	byte = READ_RTC(0x9);
156	if (byte & 0x80) {
157		byte &= 0x7f;
158		WRITE_RTC(0x9, byte);
159	}
160
161	/* enable time transfer */
162	byte = READ_RTC(0xB);
163	byte |= 0x80;
164	WRITE_RTC(0xB, byte);
165
166	/* set the function pointers */
167	rtc_get_time = rtc_ds1386_get_time;
168	rtc_set_time = rtc_ds1386_set_time;
169}
170