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LM73 bug fix for negative temperatures and cleanup 

When the LM73 temperature sensor measures a temperature below 0 C, the
current driver does not perform sign extension, so the result returned is
512 C too high.  This patch fixes the problem, and does general cleanup
of the code.

Signed-off-by: Larry Johnson <lrj@acm.org>
This commit is contained in:
Larry Johnson 2008-02-21 13:58:11 -05:00 committed by Wolfgang Denk
parent 950a392464
commit 7754f33c6f
1 changed files with 30 additions and 30 deletions
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60
drivers/hwmon/lm73.c
View File

@ -1,5 +1,5 @@
/*
* (C) Copyright 2007
* (C) Copyright 2007-2008
* Larry Johnson, lrj@acm.org
*
* based on dtt/lm75.c which is ...
@ -39,10 +39,10 @@
*/
#define DTT_I2C_DEV_CODE 0x48 /* National Semi's LM73 device */
int dtt_read(int sensor, int reg)
int dtt_read(int const sensor, int const reg)
{
int dlen;
uchar data[2];
uint8_t data[2];
/*
* Validate 'reg' param and get register size.
@ -62,27 +62,24 @@ int dtt_read(int sensor, int reg)
return -1;
}
/*
* Calculate sensor address and register.
* Try to read the register at the calculated sensor address.
*/
sensor = DTT_I2C_DEV_CODE + (sensor & 0x07); /* calculate LM73 addr */
/*
* Now try to read the register.
*/
if (i2c_read(sensor, reg, 1, data, dlen) != 0)
if (0 !=
i2c_read(DTT_I2C_DEV_CODE + (sensor & 0x07), reg, 1, data, dlen))
return -1;
/*
* Handle 2 byte result.
*/
if (2 == dlen)
return ((int)((short)data[1] + (((short)data[0]) << 8)));
return (int)((unsigned)data[0] << 8 | (unsigned)data[1]);
return (int)data[0];
} /* dtt_read() */
int dtt_write(int sensor, int reg, int val)
int dtt_write(int const sensor, int const reg, int const val)
{
int dlen;
uchar data[2];
uint8_t data[2];
/*
* Validate 'reg' param and handle register size
@ -91,28 +88,25 @@ int dtt_write(int sensor, int reg, int val)
case DTT_CONFIG:
case DTT_CONTROL:
dlen = 1;
data[0] = (char)(val & 0xff);
data[0] = (uint8_t) val;
break;
case DTT_TEMP_HIGH:
case DTT_TEMP_LOW:
dlen = 2;
data[0] = (char)((val >> 8) & 0xff); /* MSB first */
data[1] = (char)(val & 0xff);
data[0] = (uint8_t) (val >> 8); /* MSB first */
data[1] = (uint8_t) val;
break;
default:
return -1;
}
/*
* Calculate sensor address and register.
* Write value to register at the calculated sensor address.
*/
sensor = DTT_I2C_DEV_CODE + (sensor & 0x07); /* calculate LM73 addr */
/*
* Write value to register.
*/
return i2c_write(sensor, reg, 1, data, dlen) != 0;
return 0 != i2c_write(DTT_I2C_DEV_CODE + (sensor & 0x07), reg, 1, data,
dlen);
} /* dtt_write() */
static int _dtt_init(int sensor)
static int _dtt_init(int const sensor)
{
int val;
@ -120,31 +114,31 @@ static int _dtt_init(int sensor)
* Validate the Identification register
*/
if (0x0190 != dtt_read(sensor, DTT_ID))
return 1;
return -1;
/*
* Setup THIGH (upper-limit) and TLOW (lower-limit) registers
*/
val = CFG_DTT_MAX_TEMP << 7;
if (dtt_write(sensor, DTT_TEMP_HIGH, val))
return 1;
return -1;
val = CFG_DTT_MIN_TEMP << 7;
if (dtt_write(sensor, DTT_TEMP_LOW, val))
return 1;
return -1;
/*
* Setup configuraton register
*/
/* config = alert active low, disabled, and reset */
val = 0x64;
if (dtt_write(sensor, DTT_CONFIG, val))
return 1;
return -1;
/*
* Setup control/status register
*/
/* control = temp resolution 0.25C */
val = 0x00;
if (dtt_write(sensor, DTT_CONTROL, val))
return 1;
return -1;
dtt_read(sensor, DTT_CONTROL); /* clear temperature flags */
return 0;
@ -157,7 +151,7 @@ int dtt_init(void)
const char *const header = "DTT: ";
for (i = 0; i < sizeof(sensors); i++) {
if (_dtt_init(sensors[i]) != 0)
if (0 != _dtt_init(sensors[i]))
printf("%s%d FAILED INIT\n", header, i + 1);
else
printf("%s%d is %i C\n", header, i + 1,
@ -166,7 +160,13 @@ int dtt_init(void)
return 0;
} /* dtt_init() */
int dtt_get_temp(int sensor)
int dtt_get_temp(int const sensor)
{
return (dtt_read(sensor, DTT_READ_TEMP) + 0x0040) >> 7;
int const ret = dtt_read(sensor, DTT_READ_TEMP);
if (ret < 0) {
printf("DTT temperature read failed.\n");
return 0;
}
return (int)((int16_t) ret + 0x0040) >> 7;
} /* dtt_get_temp() */