diff options
| -rw-r--r-- | drivers/iio/humidity/dht11.c | 42 |
1 files changed, 22 insertions, 20 deletions
diff --git a/drivers/iio/humidity/dht11.c b/drivers/iio/humidity/dht11.c index 91976e06f1c6..1165b1c4f9d6 100644 --- a/drivers/iio/humidity/dht11.c +++ b/drivers/iio/humidity/dht11.c @@ -33,6 +33,7 @@ #include <linux/delay.h> #include <linux/gpio.h> #include <linux/of_gpio.h> +#include <linux/timekeeping.h> #include <linux/iio/iio.h> @@ -89,23 +90,11 @@ static unsigned char dht11_decode_byte(int *timing, int threshold) return ret; } -static int dht11_decode(struct dht11 *dht11, int offset) +static int dht11_decode(struct dht11 *dht11, int offset, int timeres) { - int i, t, timing[DHT11_BITS_PER_READ], threshold, - timeres = DHT11_SENSOR_RESPONSE; + int i, t, timing[DHT11_BITS_PER_READ], threshold; unsigned char temp_int, temp_dec, hum_int, hum_dec, checksum; - /* Calculate timestamp resolution */ - for (i = 1; i < dht11->num_edges; ++i) { - t = dht11->edges[i].ts - dht11->edges[i - 1].ts; - if (t > 0 && t < timeres) - timeres = t; - } - if (2 * timeres > DHT11_DATA_BIT_HIGH) { - pr_err("dht11: timeresolution %d too bad for decoding\n", - timeres); - return -EIO; - } threshold = DHT11_DATA_BIT_HIGH / timeres; if (DHT11_DATA_BIT_LOW / timeres + 1 >= threshold) pr_err("dht11: WARNING: decoding ambiguous\n"); @@ -128,7 +117,7 @@ static int dht11_decode(struct dht11 *dht11, int offset) if (((hum_int + hum_dec + temp_int + temp_dec) & 0xff) != checksum) return -EIO; - dht11->timestamp = iio_get_time_ns(); + dht11->timestamp = ktime_get_real_ns(); if (hum_int < 20) { /* DHT22 */ dht11->temperature = (((temp_int & 0x7f) << 8) + temp_dec) * ((temp_int & 0x80) ? -100 : 100); @@ -156,7 +145,7 @@ static irqreturn_t dht11_handle_irq(int irq, void *data) /* TODO: Consider making the handler safe for IRQ sharing */ if (dht11->num_edges < DHT11_EDGES_PER_READ && dht11->num_edges >= 0) { - dht11->edges[dht11->num_edges].ts = iio_get_time_ns(); + dht11->edges[dht11->num_edges].ts = ktime_get_real_ns(); dht11->edges[dht11->num_edges++].value = gpio_get_value(dht11->gpio); @@ -172,10 +161,22 @@ static int dht11_read_raw(struct iio_dev *iio_dev, int *val, int *val2, long m) { struct dht11 *dht11 = iio_priv(iio_dev); - int ret; + int ret, timeres; mutex_lock(&dht11->lock); - if (dht11->timestamp + DHT11_DATA_VALID_TIME < iio_get_time_ns()) { + if (dht11->timestamp + DHT11_DATA_VALID_TIME < ktime_get_real_ns()) { + timeres = ktime_get_resolution_ns(); + if (DHT11_DATA_BIT_HIGH < 2 * timeres) { + dev_err(dht11->dev, "timeresolution %dns too low\n", + timeres); + /* In theory a better clock could become available + * at some point ... and there is no error code + * that really fits better. + */ + ret = -EAGAIN; + goto err; + } + reinit_completion(&dht11->completion); dht11->num_edges = 0; @@ -210,7 +211,8 @@ static int dht11_read_raw(struct iio_dev *iio_dev, ret = dht11_decode(dht11, dht11->num_edges == DHT11_EDGES_PER_READ ? DHT11_EDGES_PREAMBLE : - DHT11_EDGES_PREAMBLE - 2); + DHT11_EDGES_PREAMBLE - 2, + timeres); if (ret) goto err; } @@ -277,7 +279,7 @@ static int dht11_probe(struct platform_device *pdev) return -EINVAL; } - dht11->timestamp = iio_get_time_ns() - DHT11_DATA_VALID_TIME - 1; + dht11->timestamp = ktime_get_real_ns() - DHT11_DATA_VALID_TIME - 1; dht11->num_edges = -1; platform_set_drvdata(pdev, iio); |