static int dht11_decode(struct dht11 *dht11, int offset, int timeres)
{
int i, t, timing[DHT11_BITS_PER_READ], threshold;
unsigned char temp_int, temp_dec, hum_int, hum_dec, checksum;
threshold = DHT11_DATA_BIT_HIGH / timeres;
if (DHT11_DATA_BIT_LOW / timeres + 1 >= threshold)
pr_err("dht11: WARNING: decoding ambiguous\n");
/* scale down with timeres and check validity */
for (i = 0; i < DHT11_BITS_PER_READ; ++i) {
t = dht11->edges[offset + 2 * i + 2].ts -
dht11->edges[offset + 2 * i + 1].ts;
if (!dht11->edges[offset + 2 * i + 1].value)
return -EIO; /* lost synchronisation */
timing[i] = t / timeres;
}
hum_int = dht11_decode_byte(timing, threshold);
hum_dec = dht11_decode_byte(&timing[8], threshold);
temp_int = dht11_decode_byte(&timing[16], threshold);
temp_dec = dht11_decode_byte(&timing[24], threshold);
checksum = dht11_decode_byte(&timing[32], threshold);
if (((hum_int + hum_dec + temp_int + temp_dec) & 0xff) != checksum)
return -EIO;
dht11->timestamp = ktime_get_real_ns();
if (hum_int < 20) { /* DHT22 */
dht11->temperature = (((temp_int & 0x7f) << 8) + temp_dec) *
((temp_int & 0x80) ? -100 : 100);
dht11->humidity = ((hum_int << 8) + hum_dec) * 100;
} else if (temp_dec == 0 && hum_dec == 0) { /* DHT11 */
dht11->temperature = temp_int * 1000;
dht11->humidity = hum_int * 1000;
} else {
dev_err(dht11->dev,
"Don't know how to decode data: %d %d %d %d\n",
hum_int, hum_dec, temp_int, temp_dec);
return -EIO;
}
return 0;
}
static int dht11_decode(struct dht11 *dht11, int offset)
{
int i, t;
char bits[DHT11_BITS_PER_READ];
unsigned char temp_int, temp_dec, hum_int, hum_dec, checksum;
for (i = 0; i < DHT11_BITS_PER_READ; ++i) {
t = dht11->edges[offset + 2 * i + 2].ts -
dht11->edges[offset + 2 * i + 1].ts;
if (!dht11->edges[offset + 2 * i + 1].value)
return -EIO; /* lost synchronisation */
bits[i] = t > DHT11_THRESHOLD;
}
hum_int = dht11_decode_byte(bits);
hum_dec = dht11_decode_byte(&bits[8]);
temp_int = dht11_decode_byte(&bits[16]);
temp_dec = dht11_decode_byte(&bits[24]);
checksum = dht11_decode_byte(&bits[32]);
if (((hum_int + hum_dec + temp_int + temp_dec) & 0xff) != checksum)
return -EIO;
dht11->timestamp = ktime_get_boot_ns();
if (hum_int < 20) { /* DHT22 */
dht11->temperature = (((temp_int & 0x7f) << 8) + temp_dec) *
((temp_int & 0x80) ? -100 : 100);
dht11->humidity = ((hum_int << 8) + hum_dec) * 100;
} else if (temp_dec == 0 && hum_dec == 0) { /* DHT11 */
dht11->temperature = temp_int * 1000;
dht11->humidity = hum_int * 1000;
} else {
dev_err(dht11->dev,
"Don't know how to decode data: %d %d %d %d\n",
hum_int, hum_dec, temp_int, temp_dec);
return -EIO;
}
return 0;
}
