Implement INDIO_BUFFER_SOFTWARE mode to allow continuous sampling without
relying upon external trigger.
Sampling is carried out by a kthread which life cycle is bound to samples
buffering: it is created at postenable time and destroyed at predisable
time.
Signed-off-by: Gregor Boirie <gregor.boirie@xxxxxxxxxx>
---
drivers/iio/pressure/ms5611.h | 8 +++
drivers/iio/pressure/ms5611_core.c | 117 ++++++++++++++++++++++++++++++-------
2 files changed, 105 insertions(+), 20 deletions(-)
diff --git a/drivers/iio/pressure/ms5611.h b/drivers/iio/pressure/ms5611.h
index b07897f..27edd384 100644
--- a/drivers/iio/pressure/ms5611.h
+++ b/drivers/iio/pressure/ms5611.h
@@ -44,10 +44,17 @@ struct ms5611_osr {
unsigned short rate;
};
+/*
+ * Number of s32 for a complete sample, i.e. s32 (pressure) + s32 (temp) +
+ * 2 * s32 (timestamp).
+ */
+#define MS5611_BUFFER_NR (4U)
+
struct ms5611_state {
void *client;
struct mutex lock;
+ s32 buf[MS5611_BUFFER_NR];
const struct ms5611_osr *pressure_osr;
const struct ms5611_osr *temp_osr;
@@ -57,6 +64,7 @@ struct ms5611_state {
s32 *temp, s32 *pressure);
struct ms5611_chip_info *chip_info;
+ struct task_struct *task;
};
int ms5611_probe(struct iio_dev *indio_dev, struct device *dev,
diff --git a/drivers/iio/pressure/ms5611_core.c b/drivers/iio/pressure/ms5611_core.c
index 06d453c..443a0ce 100644
--- a/drivers/iio/pressure/ms5611_core.c
+++ b/drivers/iio/pressure/ms5611_core.c
@@ -14,16 +14,22 @@
*/
#include <linux/module.h>
-#include <linux/iio/iio.h>
#include <linux/delay.h>
+#include <linux/kthread.h>
+#include <linux/freezer.h>
#include <linux/regulator/consumer.h>
-
+#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#include <linux/iio/buffer.h>
#include <linux/iio/triggered_buffer.h>
#include <linux/iio/trigger_consumer.h>
#include "ms5611.h"
+enum {
+ MS5611_PRESSURE = 0,
+ MS5611_TEMP = 1
+};
+
#define MS5611_INIT_OSR(_cmd, _conv_usec, _rate) \
{ .cmd = _cmd, .conv_usec = _conv_usec, .rate = _rate }
@@ -210,25 +216,28 @@ static int ms5611_reset(struct iio_dev *indio_dev)
return 0;
}
-static irqreturn_t ms5611_trigger_handler(int irq, void *p)
+static void ms5611_push_data(struct iio_dev *indio_dev,
+ struct ms5611_state *state)
{
- struct iio_poll_func *pf = p;
- struct iio_dev *indio_dev = pf->indio_dev;
- struct ms5611_state *st = iio_priv(indio_dev);
- s32 buf[4]; /* s32 (pressure) + s32 (temp) + 2 * s32 (timestamp) */
int ret;
- mutex_lock(&st->lock);
- ret = ms5611_read_temp_and_pressure(indio_dev, &buf[1], &buf[0]);
- mutex_unlock(&st->lock);
- if (ret < 0)
- goto err;
+ mutex_lock(&state->lock);
+ ret = ms5611_read_temp_and_pressure(indio_dev, &state->buf[MS5611_TEMP],
+ &state->buf[MS5611_PRESSURE]);
+ mutex_unlock(&state->lock);
- iio_push_to_buffers_with_timestamp(indio_dev, buf, iio_get_time_ns());
+ if (!ret)
+ iio_push_to_buffers_with_timestamp(indio_dev, state->buf,
+ iio_get_time_ns());
+}
-err:
- iio_trigger_notify_done(indio_dev->trig);
+static irqreturn_t ms5611_trigger_handler(int irq, void *p)
+{
+ const struct iio_poll_func *pf = p;
+ struct iio_dev *indio_dev = pf->indio_dev;
+ ms5611_push_data(indio_dev, iio_priv(indio_dev));
+ iio_trigger_notify_done(indio_dev->trig);
return IRQ_HANDLED;
}
@@ -236,15 +245,24 @@ static int ms5611_read_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int *val, int *val2, long mask)
{
- int ret;
+ int ret = 0;
s32 temp, pressure;
struct ms5611_state *st = iio_priv(indio_dev);
switch (mask) {
case IIO_CHAN_INFO_PROCESSED:
mutex_lock(&st->lock);
- ret = ms5611_read_temp_and_pressure(indio_dev,
- &temp, &pressure);
+ if (iio_buffer_enabled(indio_dev)) {
+ /*
+ * Return "cached" data since sampling is ongoing in the
+ * background.
+ */
+ pressure = st->buf[MS5611_PRESSURE];
+ temp = st->buf[MS5611_TEMP];
+ }
+ else
+ ret = ms5611_read_temp_and_pressure(indio_dev, &temp,
+ &pressure);
mutex_unlock(&st->lock);
if (ret < 0)
return ret;
@@ -384,6 +402,64 @@ static const struct iio_info ms5611_info = {
.driver_module = THIS_MODULE,
};
+static int ms5611d(void *data)
+{
+ struct iio_dev *indio_dev = data;
+ struct ms5611_state *st = iio_priv(indio_dev);
+
+ set_freezable();
+
+ do {
+ ms5611_push_data(indio_dev, st);
+ } while (likely(!kthread_freezable_should_stop(NULL)));
+
+ return 0;
+}
+
+static int ms5611_buffer_postenable(struct iio_dev *indio_dev)
+{
+ struct ms5611_state *st = iio_priv(indio_dev);
+ int ret;
+
+ /*
+ * Initialize temperature and pressure so that a client getting samples
+ * through read_raw retrieves valid data when buffering has just been
+ * enabled but first sampling round is not yet completed.
+ */
+ mutex_lock(&st->lock);
+ ret = ms5611_read_temp_and_pressure(indio_dev, &st->buf[MS5611_TEMP],
+ &st->buf[MS5611_PRESSURE]);
+ mutex_unlock(&st->lock);
+ if (ret < 0)
+ return ret;
+
+ if (indio_dev->currentmode == INDIO_BUFFER_TRIGGERED)
+ return iio_triggered_buffer_postenable(indio_dev);
+
+ st->task = kthread_run(ms5611d, indio_dev, indio_dev->name);
+ if (unlikely(IS_ERR(st->task))) {
+ dev_err(&indio_dev->dev, "failed to create buffering task\n");
+ return PTR_ERR(st->task);
+ }
+
+ return 0;
+}
+
+static int ms5611_buffer_predisable(struct iio_dev *indio_dev)
+{
+
+ if (indio_dev->currentmode == INDIO_BUFFER_TRIGGERED)
+ return iio_triggered_buffer_predisable(indio_dev);
+
+ kthread_stop(((struct ms5611_state*) iio_priv(indio_dev))->task);
+ return 0;
+}
+
+static const struct iio_buffer_setup_ops ms5611_buffer_ops = {
+ .postenable = ms5611_buffer_postenable,
+ .predisable = ms5611_buffer_predisable,
+};
+
static int ms5611_init(struct iio_dev *indio_dev)
{
int ret;
@@ -425,7 +501,7 @@ int ms5611_probe(struct iio_dev *indio_dev, struct device *dev,
indio_dev->info = &ms5611_info;
indio_dev->channels = ms5611_channels;
indio_dev->num_channels = ARRAY_SIZE(ms5611_channels);
- indio_dev->modes = INDIO_DIRECT_MODE;
+ indio_dev->modes = INDIO_DIRECT_MODE | INDIO_BUFFER_SOFTWARE;
indio_dev->available_scan_masks = ms5611_scan_masks;
ret = ms5611_init(indio_dev);
@@ -433,7 +509,8 @@ int ms5611_probe(struct iio_dev *indio_dev, struct device *dev,
return ret;
ret = iio_triggered_buffer_setup(indio_dev, NULL,
- ms5611_trigger_handler, NULL);
+ ms5611_trigger_handler,
+ &ms5611_buffer_ops);
if (ret < 0) {
dev_err(dev, "iio triggered buffer setup failed\n");
return ret;
--
2.1.4
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