Merge branch 'for-linus' of git://oss.sgi.com:8090/xfs/xfs-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 #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 */
24 static void rtc_reg_write(unsigned long val)
25 {
26         *ds1603->reg = val;
27 }
28
29 static unsigned long rtc_reg_read(void)
30 {
31         unsigned long tmp = *ds1603->reg;
32         return tmp;
33 }
34
35 static unsigned long rtc_datareg_read(void)
36 {
37         unsigned long tmp = *ds1603->data_reg;
38         return tmp;
39 }
40
41 static void rtc_nrst_high(void)
42 {
43         rtc_reg_write(rtc_reg_read() | ds1603->rst);
44 }
45
46 static void rtc_nrst_low(void)
47 {
48         rtc_reg_write(rtc_reg_read() & ~ds1603->rst);
49 }
50
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
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
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
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
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
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
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
132 static void rtc_end_op(void)
133 {
134         rtc_nrst_low();
135         lasat_ndelay(1000);
136 }
137
138 unsigned long read_persistent_clock(void)
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         return word;
151 }
152
153 int rtc_mips_set_mmss(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
167 void 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
175 void ds1603_disable(void)
176 {
177         ds1603_set_trimmer(TRIMMER_DISABLE_RTC);
178 }
179
180 void ds1603_enable(void)
181 {
182         ds1603_set_trimmer(TRIMMER_DEFAULT);
183 }