MODULE_AUTHOR("Evgeniy Polyakov <johnpol@2ka.mipt.ru>");
MODULE_DESCRIPTION("Driver for 1-wire Dallas network protocol, temperature family.");
+/* Allow the strong pullup to be disabled, but default to enabled.
+ * If it was disabled a parasite powered device might not get the require
+ * current to do a temperature conversion. If it is enabled parasite powered
+ * devices have a better chance of getting the current required.
+ */
+static int w1_strong_pullup = 1;
+module_param_named(strong_pullup, w1_strong_pullup, int, 0);
+
static u8 bad_roms[][9] = {
{0xaa, 0x00, 0x4b, 0x46, 0xff, 0xff, 0x0c, 0x10, 0x87},
{}
int (*convert)(u8 rom[9]);
};
+/* The return value is millidegrees Centigrade. */
static inline int w1_DS18B20_convert_temp(u8 rom[9]);
static inline int w1_DS18S20_convert_temp(u8 rom[9]);
static inline int w1_DS18B20_convert_temp(u8 rom[9])
{
- int t = (rom[1] << 8) | rom[0];
- t /= 16;
+ s16 t = (rom[1] << 8) | rom[0];
+ t = t*1000/16;
return t;
}
int count = 0;
unsigned int tm = 750;
+ /* 750ms strong pullup (or delay) after the convert */
+ if (w1_strong_pullup)
+ w1_next_pullup(dev, tm);
w1_write_8(dev, W1_CONVERT_TEMP);
-
- msleep(tm);
+ if (!w1_strong_pullup)
+ msleep(tm);
if (!w1_reset_select_slave(sl)) {
crc = w1_calc_crc8(rom, 8);
- if (rom[8] == crc && rom[0])
+ if (rom[8] == crc)
verdict = 1;
}
}