summaryrefslogtreecommitdiff
path: root/drivers/hwmon/ds1722.c
blob: c19ee01393f087af4c294836d97d41bb911cee57 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142

#include <common.h>

#ifdef CONFIG_DS1722

#include <ssi.h>

static void ds1722_select(int dev)
{
	ssi_set_interface(4096, 0, 0, 0);
	ssi_chip_select(0);
	udelay(1);
	ssi_chip_select(dev);
	udelay(1);
}


u8 ds1722_read(int dev, int addr)
{
	u8 res;

	ds1722_select(dev);

	ssi_tx_byte(addr);
	res = ssi_rx_byte();

	ssi_chip_select(0);

	return res;
}

void ds1722_write(int dev, int addr, u8 data)
{
	ds1722_select(dev);

	ssi_tx_byte(0x80|addr);
	ssi_tx_byte(data);

	ssi_chip_select(0);
}


u16 ds1722_temp(int dev, int resolution)
{
	static int useconds[] = {
		75000, 150000, 300000, 600000, 1200000
	};
	char temp;
	u16 res;


	/* set up the desired resulotion ... */
	ds1722_write(dev, 0, 0xe0 | (resolution << 1));

	/* wait while the chip measures the tremperature */
	udelay(useconds[resolution]);

	res = (temp = ds1722_read(dev, 2)) << 8;

	if (temp < 0) {
		temp = (16 - (ds1722_read(dev, 1) >> 4)) & 0x0f;
	} else {
		temp = (ds1722_read(dev, 1) >> 4);
	}

	switch (temp) {
	case 0:
		/* .0000 */
		break;
	case 1:
		/* .0625 */
		res |=1;
		break;
	case 2:
		/* .1250 */
		res |=1;
		break;
	case 3:
		/* .1875 */
		res |=2;
		break;
	case 4:
		/* .2500 */
		res |=3;
		break;
	case 5:
		/* .3125 */
		res |=3;
		break;
	case 6:
		/* .3750 */
		res |=4;
		break;
	case 7:
		/* .4375 */
		res |=4;
		break;
	case 8:
		/* .5000 */
		res |=5;
		break;
	case 9:
		/* .5625 */
		res |=6;
		break;
	case 10:
		/* .6250 */
		res |=6;
		break;
	case 11:
		/* .6875 */
		res |=7;
		break;
	case 12:
		/* .7500 */
		res |=8;
		break;
	case 13:
		/* .8125 */
		res |=8;
		break;
	case 14:
		/* .8750 */
		res |=9;
		break;
	case 15:
		/* .9375 */
		res |=9;
		break;
	}
	return res;

}

int ds1722_probe(int dev)
{
	u16 temp = ds1722_temp(dev, DS1722_RESOLUTION_12BIT);
	printf("%d.%d deg C\n\n", (char)(temp >> 8), temp & 0xff);
	return 0;
}

#endif