1/*
2 * Dallas Semiconductors 1603 RTC driver
3 *
4 * Brian Murphy <brian@murphy.dk>
5 *
6 */
7#include <linux/kernel.h>
8#include <asm/lasat/lasat.h>
9#include <linux/delay.h>
10#include <asm/lasat/ds1603.h>
11#include <asm/time.h>
12
13#include "ds1603.h"
14
15#define READ_TIME_CMD 0x81
16#define SET_TIME_CMD 0x80
17#define TRIMMER_SET_CMD 0xC0
18#define TRIMMER_VALUE_MASK 0x38
19#define TRIMMER_SHIFT 3
20
21struct ds_defs *ds1603 = NULL;
22
23/* HW specific register functions */
24static void rtc_reg_write(unsigned long val)
25{
26	*ds1603->reg = val;
27}
28
29static unsigned long rtc_reg_read(void)
30{
31	unsigned long tmp = *ds1603->reg;
32	return tmp;
33}
34
35static unsigned long rtc_datareg_read(void)
36{
37	unsigned long tmp = *ds1603->data_reg;
38	return tmp;
39}
40
41static void rtc_nrst_high(void)
42{
43	rtc_reg_write(rtc_reg_read() | ds1603->rst);
44}
45
46static void rtc_nrst_low(void)
47{
48	rtc_reg_write(rtc_reg_read() & ~ds1603->rst);
49}
50
51static void rtc_cycle_clock(unsigned long data)
52{
53	data |= ds1603->clk;
54	rtc_reg_write(data);
55	lasat_ndelay(250);
56	if (ds1603->data_reversed)
57		data &= ~ds1603->data;
58	else
59		data |= ds1603->data;
60	data &= ~ds1603->clk;
61	rtc_reg_write(data);
62	lasat_ndelay(250 + ds1603->huge_delay);
63}
64
65static void rtc_write_databit(unsigned int bit)
66{
67	unsigned long data = rtc_reg_read();
68	if (ds1603->data_reversed)
69		bit = !bit;
70	if (bit)
71		data |= ds1603->data;
72	else
73		data &= ~ds1603->data;
74
75	rtc_reg_write(data);
76	lasat_ndelay(50 + ds1603->huge_delay);
77	rtc_cycle_clock(data);
78}
79
80static unsigned int rtc_read_databit(void)
81{
82	unsigned int data;
83
84	data = (rtc_datareg_read() & (1 << ds1603->data_read_shift))
85		>> ds1603->data_read_shift;
86	rtc_cycle_clock(rtc_reg_read());
87	return data;
88}
89
90static void rtc_write_byte(unsigned int byte)
91{
92	int i;
93
94	for (i = 0; i<=7; i++) {
95		rtc_write_databit(byte & 1L);
96		byte >>= 1;
97	}
98}
99
100static void rtc_write_word(unsigned long word)
101{
102	int i;
103
104	for (i = 0; i<=31; i++) {
105		rtc_write_databit(word & 1L);
106		word >>= 1;
107	}
108}
109
110static unsigned long rtc_read_word(void)
111{
112	int i;
113	unsigned long word = 0;
114	unsigned long shift = 0;
115
116	for (i = 0; i<=31; i++) {
117		word |= rtc_read_databit() << shift;
118		shift++;
119	}
120	return word;
121}
122
123static void rtc_init_op(void)
124{
125	rtc_nrst_high();
126
127	rtc_reg_write(rtc_reg_read() & ~ds1603->clk);
128
129	lasat_ndelay(50);
130}
131
132static void rtc_end_op(void)
133{
134	rtc_nrst_low();
135	lasat_ndelay(1000);
136}
137
138/* interface */
139unsigned long ds1603_read(void)
140{
141	unsigned long word;
142	unsigned long flags;
143
144	spin_lock_irqsave(&rtc_lock, flags);
145	rtc_init_op();
146	rtc_write_byte(READ_TIME_CMD);
147	word = rtc_read_word();
148	rtc_end_op();
149	spin_unlock_irqrestore(&rtc_lock, flags);
150	return word;
151}
152
153int ds1603_set(unsigned long time)
154{
155	unsigned long flags;
156
157	spin_lock_irqsave(&rtc_lock, flags);
158	rtc_init_op();
159	rtc_write_byte(SET_TIME_CMD);
160	rtc_write_word(time);
161	rtc_end_op();
162	spin_unlock_irqrestore(&rtc_lock, flags);
163
164	return 0;
165}
166
167void ds1603_set_trimmer(unsigned int trimval)
168{
169	rtc_init_op();
170	rtc_write_byte(((trimval << TRIMMER_SHIFT) & TRIMMER_VALUE_MASK)
171			| (TRIMMER_SET_CMD));
172	rtc_end_op();
173}
174
175void ds1603_disable(void)
176{
177	ds1603_set_trimmer(TRIMMER_DISABLE_RTC);
178}
179
180void ds1603_enable(void)
181{
182	ds1603_set_trimmer(TRIMMER_DEFAULT);
183}
184