blob: 80fb26f7b5ae9e40277a8a2239583e68fed1c7ef [file] [log] [blame]
John Otkend4024bb2007-07-26 17:49:11 +02001/*
2 * This program is free software; you can redistribute it and/or
3 * modify it under the terms of the GNU General Public License as
4 * published by the Free Software Foundation; either version 2 of
5 * the License, or (at your option) any later version.
6 *
7 * This program is distributed in the hope that it will be useful,
8 * but WITHOUT ANY WARRANTY; without even the implied warranty of
9 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
10 * GNU General Public License for more details.
11 *
12 * You should have received a copy of the GNU General Public License
13 * along with this program; if not, write to the Free Software
14 * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
15 * MA 02111-1307 USA
16 */
17
18/*
19 * Dallas Semiconductor's DS1775 Digital Thermometer and Thermostat
20 */
21
22#include <common.h>
23
John Otkend4024bb2007-07-26 17:49:11 +020024#include <i2c.h>
25#include <dtt.h>
26
Jean-Christophe PLAGNIOL-VILLARD6d0f6bc2008-10-16 15:01:15 +020027#define DTT_I2C_DEV_CODE CONFIG_SYS_I2C_DTT_ADDR /* Dallas Semi's DS1775 device code */
Michal Simek6ecbb452008-07-11 11:50:53 +020028#define DTT_READ_TEMP 0x0
29#define DTT_CONFIG 0x1
30#define DTT_TEMP_HYST 0x2
31#define DTT_TEMP_OS 0x3
John Otkend4024bb2007-07-26 17:49:11 +020032
33int dtt_read(int sensor, int reg)
34{
35 int dlen;
36 uchar data[2];
37
38 /*
39 * Calculate sensor address and command
40 */
41 sensor = DTT_I2C_DEV_CODE + (sensor & 0x07); /* Calculate addr of ds1775 */
42
43 /*
44 * Prepare to handle 2 byte result
45 */
46 if ((reg == DTT_READ_TEMP) ||
47 (reg == DTT_TEMP_OS) || (reg == DTT_TEMP_HYST))
48 dlen = 2;
49 else
50 dlen = 1;
51
52 /*
53 * Now try to read the register
54 */
55 if (i2c_read(sensor, reg, 1, data, dlen) != 0)
56 return 1;
57
58 /*
59 * Handle 2 byte result
60 */
61 if (dlen == 2)
62 return ((int)((short)data[1] + (((short)data[0]) << 8)));
63
64 return (int) data[0];
65}
66
67
68int dtt_write(int sensor, int reg, int val)
69{
70 int dlen;
71 uchar data[2];
72
73 /*
74 * Calculate sensor address and register
75 */
76 sensor = DTT_I2C_DEV_CODE + (sensor & 0x07);
77
78 /*
79 * Handle various data sizes
80 */
81 if ((reg == DTT_READ_TEMP) ||
82 (reg == DTT_TEMP_OS) || (reg == DTT_TEMP_HYST)) {
83 dlen = 2;
84 data[0] = (char)((val >> 8) & 0xff); /* MSB first */
85 data[1] = (char)(val & 0xff);
86 } else {
87 dlen = 1;
88 data[0] = (char)(val & 0xff);
89 }
90
91 /*
92 * Write value to device
93 */
94 if (i2c_write(sensor, reg, 1, data, dlen) != 0)
95 return 1;
96
97 return 0;
98}
99
100
101static int _dtt_init(int sensor)
102{
103 int val;
104
105 /*
106 * Setup High Temp
107 */
Jean-Christophe PLAGNIOL-VILLARD6d0f6bc2008-10-16 15:01:15 +0200108 val = ((CONFIG_SYS_DTT_MAX_TEMP * 2) << 7) & 0xff80;
John Otkend4024bb2007-07-26 17:49:11 +0200109 if (dtt_write(sensor, DTT_TEMP_OS, val) != 0)
110 return 1;
111 udelay(50000); /* Max 50ms */
112
113 /*
114 * Setup Low Temp - hysteresis
115 */
Jean-Christophe PLAGNIOL-VILLARD6d0f6bc2008-10-16 15:01:15 +0200116 val = (((CONFIG_SYS_DTT_MAX_TEMP - CONFIG_SYS_DTT_HYSTERESIS) * 2) << 7) & 0xff80;
John Otkend4024bb2007-07-26 17:49:11 +0200117 if (dtt_write(sensor, DTT_TEMP_HYST, val) != 0)
118 return 1;
119 udelay(50000); /* Max 50ms */
120
121 /*
122 * Setup configuraton register
123 *
124 * Fault Tolerance limits 4, Thermometer resolution bits is 9,
125 * Polarity = Active Low,continuous conversion mode, Thermostat
126 * mode is interrupt mode
127 */
128 val = 0xa;
129 if (dtt_write(sensor, DTT_CONFIG, val) != 0)
130 return 1;
131 udelay(50000); /* Max 50ms */
132
133 return 0;
134}
135
136
137int dtt_init (void)
138{
139 int i;
140 unsigned char sensors[] = CONFIG_DTT_SENSORS;
141
142 for (i = 0; i < sizeof(sensors); i++) {
143 if (_dtt_init(sensors[i]) != 0)
144 printf("DTT%d: FAILED\n", i+1);
145 else
146 printf("DTT%d: %i C\n", i+1, dtt_get_temp(sensors[i]));
147 }
148
149 return (0);
150}
151
152
153int dtt_get_temp(int sensor)
154{
155 return (dtt_read(sensor, DTT_READ_TEMP) / 256);
156}