iio: hx711: add triggered buffer support

Add buffer to device data struct and add trigger function

Data format is quite simple:
      voltage - channel 0   32 Bit
      voltage - channel 1   32 Bit
      timestamp             64 Bit

Using both channels at the same time is working quite slow because of
changing the channel which needs a dummy read.

Signed-off-by: Andreas Klinger <ak@it-klinger.de>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 4867936..47492c9 100644 (file)
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -319,6 +319,8 @@ config HI8435
 config HX711
        tristate "AVIA HX711 ADC for weight cells"
        depends on GPIOLIB
+       select IIO_BUFFER
+       select IIO_TRIGGERED_BUFFER
        help
          If you say yes here you get support for AVIA HX711 ADC which is used
          for weigh cells

diff --git a/drivers/iio/adc/hx711.c b/drivers/iio/adc/hx711.c
index d10b9f1..a38162e 100644 (file)
--- a/drivers/iio/adc/hx711.c
+++ b/drivers/iio/adc/hx711.c
@@ -24,6 +24,9 @@
 #include <linux/delay.h>
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
+#include <linux/iio/buffer.h>
+#include <linux/iio/trigger_consumer.h>
+#include <linux/iio/triggered_buffer.h>
 #include <linux/gpio/consumer.h>
 #include <linux/regulator/consumer.h>
 
@@ -89,6 +92,11 @@ struct hx711_data {
        int                     gain_set;       /* gain set on device */
        int                     gain_chan_a;    /* gain for channel A */
        struct mutex            lock;
+       /*
+        * triggered buffer
+        * 2x32-bit channel + 64-bit timestamp
+        */
+       u32                     buffer[4];
 };
 
 static int hx711_cycle(struct hx711_data *hx711_data)
@@ -236,34 +244,40 @@ static int hx711_set_gain_for_channel(struct hx711_data *hx711_data, int chan)
        return 0;
 }
 
+static int hx711_reset_read(struct hx711_data *hx711_data, int chan)
+{
+       int ret;
+       int val;
+
+       /*
+        * hx711_reset() must be called from here
+        * because it could be calling hx711_read() by itself
+        */
+       if (hx711_reset(hx711_data)) {
+               dev_err(hx711_data->dev, "reset failed!");
+               return -EIO;
+       }
+
+       ret = hx711_set_gain_for_channel(hx711_data, chan);
+       if (ret < 0)
+               return ret;
+
+       val = hx711_read(hx711_data);
+
+       return val;
+}
+
 static int hx711_read_raw(struct iio_dev *indio_dev,
                                const struct iio_chan_spec *chan,
                                int *val, int *val2, long mask)
 {
        struct hx711_data *hx711_data = iio_priv(indio_dev);
-       int ret;
 
        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                mutex_lock(&hx711_data->lock);
 
-               /*
-                * hx711_reset() must be called from here
-                * because it could be calling hx711_read() by itself
-                */
-               if (hx711_reset(hx711_data)) {
-                       mutex_unlock(&hx711_data->lock);
-                       dev_err(hx711_data->dev, "reset failed!");
-                       return -EIO;
-               }
-
-               ret = hx711_set_gain_for_channel(hx711_data, chan->channel);
-               if (ret < 0) {
-                       mutex_unlock(&hx711_data->lock);
-                       return ret;
-               }
-
-               *val = hx711_read(hx711_data);
+               *val = hx711_reset_read(hx711_data, chan->channel);
 
                mutex_unlock(&hx711_data->lock);
 
@@ -339,6 +353,36 @@ static int hx711_write_raw_get_fmt(struct iio_dev *indio_dev,
        return IIO_VAL_INT_PLUS_NANO;
 }
 
+static irqreturn_t hx711_trigger(int irq, void *p)
+{
+       struct iio_poll_func *pf = p;
+       struct iio_dev *indio_dev = pf->indio_dev;
+       struct hx711_data *hx711_data = iio_priv(indio_dev);
+       int i, j = 0;
+
+       mutex_lock(&hx711_data->lock);
+
+       memset(hx711_data->buffer, 0, sizeof(hx711_data->buffer));
+
+       for (i = 0; i < indio_dev->masklength; i++) {
+               if (!test_bit(i, indio_dev->active_scan_mask))
+                       continue;
+
+               hx711_data->buffer[j] = hx711_reset_read(hx711_data,
+                                       indio_dev->channels[i].channel);
+               j++;
+       }
+
+       iio_push_to_buffers_with_timestamp(indio_dev, hx711_data->buffer,
+                                                       pf->timestamp);
+
+       mutex_unlock(&hx711_data->lock);
+
+       iio_trigger_notify_done(indio_dev->trig);
+
+       return IRQ_HANDLED;
+}
+
 static ssize_t hx711_scale_available_show(struct device *dev,
                                struct device_attribute *attr,
                                char *buf)
@@ -387,6 +431,13 @@ static const struct iio_chan_spec hx711_chan_spec[] = {
                .indexed = 1,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
                .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
+               .scan_index = 0,
+               .scan_type = {
+                       .sign = 'u',
+                       .realbits = 24,
+                       .storagebits = 32,
+                       .endianness = IIO_CPU,
+               },
        },
        {
                .type = IIO_VOLTAGE,
@@ -394,7 +445,15 @@ static const struct iio_chan_spec hx711_chan_spec[] = {
                .indexed = 1,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
                .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
+               .scan_index = 1,
+               .scan_type = {
+                       .sign = 'u',
+                       .realbits = 24,
+                       .storagebits = 32,
+                       .endianness = IIO_CPU,
+               },
        },
+       IIO_CHAN_SOFT_TIMESTAMP(2),
 };
 
 static int hx711_probe(struct platform_device *pdev)
@@ -459,10 +518,9 @@ static int hx711_probe(struct platform_device *pdev)
         * 1 LSB = (AVDD * 100) / GAIN / 1678 [10^-9 mV]
         */
        ret = regulator_get_voltage(hx711_data->reg_avdd);
-       if (ret < 0) {
-               regulator_disable(hx711_data->reg_avdd);
-               return ret;
-       }
+       if (ret < 0)
+               goto error_regulator;
+
        /* we need 10^-9 mV */
        ret *= 100;
 
@@ -482,12 +540,27 @@ static int hx711_probe(struct platform_device *pdev)
        indio_dev->channels = hx711_chan_spec;
        indio_dev->num_channels = ARRAY_SIZE(hx711_chan_spec);
 
+       ret = iio_triggered_buffer_setup(indio_dev, iio_pollfunc_store_time,
+                                                       hx711_trigger, NULL);
+       if (ret < 0) {
+               dev_err(dev, "setup of iio triggered buffer failed\n");
+               goto error_regulator;
+       }
+
        ret = iio_device_register(indio_dev);
        if (ret < 0) {
                dev_err(dev, "Couldn't register the device\n");
-               regulator_disable(hx711_data->reg_avdd);
+               goto error_buffer;
        }
 
+       return 0;
+
+error_buffer:
+       iio_triggered_buffer_cleanup(indio_dev);
+
+error_regulator:
+       regulator_disable(hx711_data->reg_avdd);
+
        return ret;
 }
 
@@ -501,6 +574,8 @@ static int hx711_remove(struct platform_device *pdev)
 
        iio_device_unregister(indio_dev);
 
+       iio_triggered_buffer_cleanup(indio_dev);
+
        regulator_disable(hx711_data->reg_avdd);
 
        return 0;