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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 
21 struct ds_defs *ds1603;
22 
23 /* HW specific register functions */
rtc_reg_write(unsigned long val)24 static void rtc_reg_write(unsigned long val)
25 {
26 	*ds1603->reg = val;
27 }
28 
rtc_reg_read(void)29 static unsigned long rtc_reg_read(void)
30 {
31 	unsigned long tmp = *ds1603->reg;
32 	return tmp;
33 }
34 
rtc_datareg_read(void)35 static unsigned long rtc_datareg_read(void)
36 {
37 	unsigned long tmp = *ds1603->data_reg;
38 	return tmp;
39 }
40 
rtc_nrst_high(void)41 static void rtc_nrst_high(void)
42 {
43 	rtc_reg_write(rtc_reg_read() | ds1603->rst);
44 }
45 
rtc_nrst_low(void)46 static void rtc_nrst_low(void)
47 {
48 	rtc_reg_write(rtc_reg_read() & ~ds1603->rst);
49 }
50 
rtc_cycle_clock(unsigned long data)51 static 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 
rtc_write_databit(unsigned int bit)65 static 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 
rtc_read_databit(void)80 static 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 
rtc_write_byte(unsigned int byte)90 static 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 
rtc_write_word(unsigned long word)100 static 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 
rtc_read_word(void)110 static 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 
rtc_init_op(void)123 static 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 
rtc_end_op(void)132 static void rtc_end_op(void)
133 {
134 	rtc_nrst_low();
135 	lasat_ndelay(1000);
136 }
137 
read_persistent_clock(struct timespec * ts)138 void read_persistent_clock(struct timespec *ts)
139 {
140 	unsigned long word;
141 	unsigned long flags;
142 
143 	spin_lock_irqsave(&rtc_lock, flags);
144 	rtc_init_op();
145 	rtc_write_byte(READ_TIME_CMD);
146 	word = rtc_read_word();
147 	rtc_end_op();
148 	spin_unlock_irqrestore(&rtc_lock, flags);
149 
150 	ts->tv_sec = word;
151 	ts->tv_nsec = 0;
152 }
153 
rtc_mips_set_mmss(unsigned long time)154 int rtc_mips_set_mmss(unsigned long time)
155 {
156 	unsigned long flags;
157 
158 	spin_lock_irqsave(&rtc_lock, flags);
159 	rtc_init_op();
160 	rtc_write_byte(SET_TIME_CMD);
161 	rtc_write_word(time);
162 	rtc_end_op();
163 	spin_unlock_irqrestore(&rtc_lock, flags);
164 
165 	return 0;
166 }
167 
ds1603_set_trimmer(unsigned int trimval)168 void ds1603_set_trimmer(unsigned int trimval)
169 {
170 	rtc_init_op();
171 	rtc_write_byte(((trimval << TRIMMER_SHIFT) & TRIMMER_VALUE_MASK)
172 			| (TRIMMER_SET_CMD));
173 	rtc_end_op();
174 }
175 
ds1603_disable(void)176 void ds1603_disable(void)
177 {
178 	ds1603_set_trimmer(TRIMMER_DISABLE_RTC);
179 }
180 
ds1603_enable(void)181 void ds1603_enable(void)
182 {
183 	ds1603_set_trimmer(TRIMMER_DEFAULT);
184 }
185