Enable buffered reading of samples from the LMP92064 ADC.
The main benefit of this change is being able to read out current and
voltage measurements in a single transfer, allowing instantaneous power
measurements.
Reads into the buffer can be triggered by any software triggers, e.g.
the iio-trig-hrtimer:
$ mkdir /sys/kernel/config/iio/triggers/hrtimer/my-trigger
$ cat /sys/bus/iio/devices/iio\:device3/name
lmp92064
$ iio_readdev -t my-trigger -b 16 iio:device3 | hexdump
WARNING: High-speed mode not enabled
0000000 0000 0176 0101 0001 5507 abd5 7645 1768
0000010 0000 016d 0101 0001 ee1e ac6b 7645 1768
...
Signed-off-by: Leonard Göhrs <l.goehrs@xxxxxxxxxxxxxx>
---
Changes v1->v2:
- Remove superfluous .shift = 0 initialization in scan_type.
- Replace kmalloc buffer allocation for every read with a stack
allocated structure.
A struct is used to ensure correct alignment of the timestamp field.
See e.g. adc/rockchip_saradc.c for other users of the same pattern.
- Use available_scan_masks and always push both voltage and current
measurements to the buffer.
Changes v2->v3:
- Handle errors returned by lmp92064_read_meas() out-of-line via
a goto err;
---
drivers/iio/adc/ti-lmp92064.c | 51 +++++++++++++++++++++++++++++++++++
1 file changed, 51 insertions(+)
diff --git a/drivers/iio/adc/ti-lmp92064.c b/drivers/iio/adc/ti-lmp92064.c
index c30ed824924f3..73504a27a8e22 100644
--- a/drivers/iio/adc/ti-lmp92064.c
+++ b/drivers/iio/adc/ti-lmp92064.c
@@ -16,7 +16,10 @@
#include <linux/spi/spi.h>
#include <linux/iio/iio.h>
+#include <linux/iio/buffer.h>
#include <linux/iio/driver.h>
+#include <linux/iio/triggered_buffer.h>
+#include <linux/iio/trigger_consumer.h>
#define TI_LMP92064_REG_CONFIG_A 0x0000
#define TI_LMP92064_REG_CONFIG_B 0x0001
@@ -91,6 +94,12 @@ static const struct iio_chan_spec lmp92064_adc_channels[] = {
.address = TI_LMP92064_CHAN_INC,
.info_mask_separate =
BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
+ .scan_index = TI_LMP92064_CHAN_INC,
+ .scan_type = {
+ .sign = 'u',
+ .realbits = 12,
+ .storagebits = 16,
+ },
.datasheet_name = "INC",
},
{
@@ -98,8 +107,20 @@ static const struct iio_chan_spec lmp92064_adc_channels[] = {
.address = TI_LMP92064_CHAN_INV,
.info_mask_separate =
BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE),
+ .scan_index = TI_LMP92064_CHAN_INV,
+ .scan_type = {
+ .sign = 'u',
+ .realbits = 12,
+ .storagebits = 16,
+ },
.datasheet_name = "INV",
},
+ IIO_CHAN_SOFT_TIMESTAMP(2),
+};
+
+static const unsigned long lmp92064_scan_masks[] = {
+ BIT(TI_LMP92064_CHAN_INC) | BIT(TI_LMP92064_CHAN_INV),
+ 0
};
static int lmp92064_read_meas(struct lmp92064_adc_priv *priv, u16 *res)
@@ -171,6 +192,30 @@ static int lmp92064_read_raw(struct iio_dev *indio_dev,
}
}
+static irqreturn_t lmp92064_trigger_handler(int irq, void *p)
+{
+ struct iio_poll_func *pf = p;
+ struct iio_dev *indio_dev = pf->indio_dev;
+ struct lmp92064_adc_priv *priv = iio_priv(indio_dev);
+ struct {
+ u16 values[2];
+ int64_t timestamp;
+ } data;
+ int ret;
+
+ ret = lmp92064_read_meas(priv, data.values);
+ if (ret)
+ goto err;
+
+ iio_push_to_buffers_with_timestamp(indio_dev, &data,
+ iio_get_time_ns(indio_dev));
+
+err:
+ iio_trigger_notify_done(indio_dev->trig);
+
+ return IRQ_HANDLED;
+}
+
static int lmp92064_reset(struct lmp92064_adc_priv *priv,
struct gpio_desc *gpio_reset)
{
@@ -301,6 +346,12 @@ static int lmp92064_adc_probe(struct spi_device *spi)
indio_dev->channels = lmp92064_adc_channels;
indio_dev->num_channels = ARRAY_SIZE(lmp92064_adc_channels);
indio_dev->info = &lmp92064_adc_info;
+ indio_dev->available_scan_masks = lmp92064_scan_masks;
+
+ ret = devm_iio_triggered_buffer_setup(dev, indio_dev, NULL,
+ lmp92064_trigger_handler, NULL);
+ if (ret)
+ return dev_err_probe(dev, ret, "Failed to setup buffered read\n");
return devm_iio_device_register(dev, indio_dev);
}
base-commit: 6995e2de6891c724bfeb2db33d7b87775f913ad1
--
2.39.2
