3 * Bill Hunter, Wave 7 Optics, williamhunter@mediaone.net
5 * SPDX-License-Identifier: GPL-2.0+
9 * On Semiconductor's LM75 Temperature Sensor
19 #define DTT_I2C_DEV_CODE 0x48 /* ON Semi's LM75 device */
20 #define DTT_READ_TEMP 0x0
21 #define DTT_CONFIG 0x1
22 #define DTT_TEMP_HYST 0x2
23 #define DTT_TEMP_SET 0x3
25 int dtt_read(int sensor, int reg)
30 #ifdef CONFIG_DTT_AD7414
32 * On AD7414 the first value upon bootup is not read correctly.
33 * This is most likely because of the 800ms update time of the
34 * temp register in normal update mode. To get current values
35 * each time we issue the "dtt" command including upon powerup
36 * we switch into one-short mode.
38 * Issue one-shot mode command
40 dtt_write(sensor, DTT_CONFIG, 0x64);
43 /* Validate 'reg' param */
44 if((reg < 0) || (reg > 3))
47 /* Calculate sensor address and register. */
48 sensor = DTT_I2C_DEV_CODE + (sensor & 0x07);
50 /* Prepare to handle 2 byte result. */
51 if ((reg == DTT_READ_TEMP) ||
52 (reg == DTT_TEMP_HYST) ||
53 (reg == DTT_TEMP_SET))
58 /* Now try to read the register. */
59 if (i2c_read(sensor, reg, 1, data, dlen) != 0)
62 /* Handle 2 byte result. */
64 return ((int)((short)data[1] + (((short)data[0]) << 8)));
70 int dtt_write(int sensor, int reg, int val)
75 /* Validate 'reg' param */
76 if ((reg < 0) || (reg > 3))
79 /* Calculate sensor address and register. */
80 sensor = DTT_I2C_DEV_CODE + (sensor & 0x07);
82 /* Handle 2 byte values. */
83 if ((reg == DTT_READ_TEMP) ||
84 (reg == DTT_TEMP_HYST) ||
85 (reg == DTT_TEMP_SET)) {
87 data[0] = (char)((val >> 8) & 0xff); /* MSB first */
88 data[1] = (char)(val & 0xff);
91 data[0] = (char)(val & 0xff);
94 /* Write value to register. */
95 if (i2c_write(sensor, reg, 1, data, dlen) != 0)
102 int dtt_init_one(int sensor)
106 /* Setup TSET ( trip point ) register */
107 val = ((CONFIG_SYS_DTT_MAX_TEMP * 2) << 7) & 0xff80; /* trip */
108 if (dtt_write(sensor, DTT_TEMP_SET, val) != 0)
111 /* Setup THYST ( untrip point ) register - Hysteresis */
112 val = (((CONFIG_SYS_DTT_MAX_TEMP - CONFIG_SYS_DTT_HYSTERESIS) * 2) << 7) & 0xff80;
113 if (dtt_write(sensor, DTT_TEMP_HYST, val) != 0)
116 /* Setup configuraton register */
117 #ifdef CONFIG_DTT_AD7414
118 /* config = alert active low and disabled */
121 /* config = 6 sample integration, int mode, active low, and enable */
124 if (dtt_write(sensor, DTT_CONFIG, val) != 0)
128 } /* dtt_init_one() */
130 int dtt_get_temp(int sensor)
132 int const ret = dtt_read(sensor, DTT_READ_TEMP);
135 printf("DTT temperature read failed.\n");
138 return (int)((int16_t) ret / 256);
139 } /* dtt_get_temp() */