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