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