Since setting irq-enabled GPIOs into output state is not supported
by all GPIO controllers, we need to disable the irq while requesting
sensor data. As side effect we lose a tiny bit of functionality:
Some wiring problems can't be concluded from log messages anymore.
Signed-off-by: Richard Weinberger <richard@xxxxxx>
Signed-off-by: Harald Geyer <harald@xxxxxxxxx>
---
changes since v1:
Reduce the expected number of edges per data transmission, since we
won't see the edges we generate ourselves.
drivers/iio/humidity/dht11.c | 62 +++++++++++++++++++++++------------------
1 files changed, 35 insertions(+), 27 deletions(-)
diff --git a/drivers/iio/humidity/dht11.c b/drivers/iio/humidity/dht11.c
index 7717f5c..7d79a1a 100644
--- a/drivers/iio/humidity/dht11.c
+++ b/drivers/iio/humidity/dht11.c
@@ -40,8 +40,12 @@
#define DHT11_DATA_VALID_TIME 2000000000 /* 2s in ns */
-#define DHT11_EDGES_PREAMBLE 4
+#define DHT11_EDGES_PREAMBLE 2
#define DHT11_BITS_PER_READ 40
+/*
+ * Note that when reading the sensor actually 84 edges are detected, but
+ * since the last edge is not significant, we only store 83:
+ */
#define DHT11_EDGES_PER_READ (2*DHT11_BITS_PER_READ + DHT11_EDGES_PREAMBLE + 1)
/* Data transmission timing (nano seconds) */
@@ -140,6 +144,27 @@ static int dht11_decode(struct dht11 *dht11, int offset)
return 0;
}
+/*
+ * IRQ handler called on GPIO edges
+ */
+static irqreturn_t dht11_handle_irq(int irq, void *data)
+{
+ struct iio_dev *iio = data;
+ struct dht11 *dht11 = iio_priv(iio);
+
+ /* 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++].value =
+ gpio_get_value(dht11->gpio);
+
+ if (dht11->num_edges >= DHT11_EDGES_PER_READ)
+ complete(&dht11->completion);
+ }
+
+ return IRQ_HANDLED;
+}
+
static int dht11_read_raw(struct iio_dev *iio_dev,
const struct iio_chan_spec *chan,
int *val, int *val2, long m)
@@ -160,8 +185,17 @@ static int dht11_read_raw(struct iio_dev *iio_dev,
if (ret)
goto err;
+ ret = request_irq(dht11->irq, dht11_handle_irq,
+ IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
+ iio_dev->name, iio_dev);
+ if (ret)
+ goto err;
+
ret = wait_for_completion_killable_timeout(&dht11->completion,
HZ);
+
+ free_irq(dht11->irq, iio_dev);
+
if (ret == 0 && dht11->num_edges < DHT11_EDGES_PER_READ - 1) {
dev_err(&iio_dev->dev,
"Only %d signal edges detected\n",
@@ -197,27 +231,6 @@ static const struct iio_info dht11_iio_info = {
.read_raw = dht11_read_raw,
};
-/*
- * IRQ handler called on GPIO edges
-*/
-static irqreturn_t dht11_handle_irq(int irq, void *data)
-{
- struct iio_dev *iio = data;
- struct dht11 *dht11 = iio_priv(iio);
-
- /* 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++].value =
- gpio_get_value(dht11->gpio);
-
- if (dht11->num_edges >= DHT11_EDGES_PER_READ)
- complete(&dht11->completion);
- }
-
- return IRQ_HANDLED;
-}
-
static const struct iio_chan_spec dht11_chan_spec[] = {
{ .type = IIO_TEMP,
.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED), },
@@ -260,11 +273,6 @@ static int dht11_probe(struct platform_device *pdev)
dev_err(dev, "GPIO %d has no interrupt\n", dht11->gpio);
return -EINVAL;
}
- ret = devm_request_irq(dev, dht11->irq, dht11_handle_irq,
- IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING,
- pdev->name, iio);
- if (ret)
- return ret;
dht11->timestamp = iio_get_time_ns() - DHT11_DATA_VALID_TIME - 1;
dht11->num_edges = -1;
--
1.7.2.5
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