Merge master.kernel.org:/pub/scm/linux/kernel/git/chrisw/lsm-2.6
[linux-2.6] / arch / mips / lasat / ds1603.c
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 */
23 static void rtc_reg_write(unsigned long val)
24 {
25         *ds1603->reg = val;
26 }
27
28 static unsigned long rtc_reg_read(void)
29 {
30         unsigned long tmp = *ds1603->reg;
31         return tmp;
32 }
33
34 static unsigned long rtc_datareg_read(void)
35 {
36         unsigned long tmp = *ds1603->data_reg;
37         return tmp;
38 }
39
40 static void rtc_nrst_high(void)
41 {
42         rtc_reg_write(rtc_reg_read() | ds1603->rst);
43 }
44
45 static void rtc_nrst_low(void)
46 {
47         rtc_reg_write(rtc_reg_read() & ~ds1603->rst);
48 }
49
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
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
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
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
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
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
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
131 static void rtc_end_op(void)
132 {
133         rtc_nrst_low();
134         lasat_ndelay(1000);
135 }
136
137 /* interface */
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
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
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
166 void ds1603_disable(void)
167 {
168         ds1603_set_trimmer(TRIMMER_DISABLE_RTC);
169 }
170
171 void ds1603_enable(void)
172 {
173         ds1603_set_trimmer(TRIMMER_DEFAULT);
174 }