[PATCH] iio: light: acpi-als: Add a tuning parameter interface.

[Enric Balletbo i Serra]

From: Bryan Freed <bfr...@chromium.org>

Add IIO_CHAN_INFO_CALIBSCALE to the channel to scale up or down
the raw measurements through the IIO framework.

Add IIO_CHAN_INFO_PROCESSED to provide the interface to read the
scaled measurements through the in_illuminance_input file.

Signed-off-by: Bryan Freed <bfr...@chromium.org>
Signed-off-by: Enric Balletbo i Serra <enric.balle...@collabora.com>
---
 drivers/iio/light/acpi-als.c | 59 +++++++++++++++++++++++++++++++++++++-------
 1 file changed, 50 insertions(+), 9 deletions(-)

diff --git a/drivers/iio/light/acpi-als.c b/drivers/iio/light/acpi-als.c
index f0b47c5..40837bc 100644
--- a/drivers/iio/light/acpi-als.c
+++ b/drivers/iio/light/acpi-als.c
@@ -56,7 +56,8 @@ static const struct iio_chan_spec acpi_als_channels[] = {
                },
                /* _RAW is here for backward ABI compatibility */
                .info_mask_separate     = BIT(IIO_CHAN_INFO_RAW) |
-                                         BIT(IIO_CHAN_INFO_PROCESSED),
+                                         BIT(IIO_CHAN_INFO_PROCESSED) |
+                                         BIT(IIO_CHAN_INFO_CALIBSCALE),
        },
 };
 
@@ -76,6 +77,9 @@ struct acpi_als {
        struct mutex            lock;
 
        s32                     evt_buffer[ACPI_ALS_EVT_BUFFER_SIZE];
+
+       uint                    als_scale;
+       uint                    als_uscale;
 };
 
 /*
@@ -154,25 +158,60 @@ static int acpi_als_read_raw(struct iio_dev *indio_dev,
        s32 temp_val;
        int ret;
 
-       if ((mask != IIO_CHAN_INFO_PROCESSED) && (mask != IIO_CHAN_INFO_RAW))
-               return -EINVAL;
-
        /* we support only illumination (_ALI) so far. */
        if (chan->type != IIO_LIGHT)
                return -EINVAL;
 
-       ret = acpi_als_read_value(als, ACPI_ALS_ILLUMINANCE, &temp_val);
-       if (ret < 0)
-               return ret;
+       switch (mask) {
+       case IIO_CHAN_INFO_RAW:
+       case IIO_CHAN_INFO_PROCESSED:
+               ret = acpi_als_read_value(als, ACPI_ALS_ILLUMINANCE, &temp_val);
+               if (ret < 0)
+                       return ret;
+               if (mask == IIO_CHAN_INFO_PROCESSED) {
+                       /* use u64 to avoid overflow */
+                       u64 ulux = (u64) temp_val * 1000000;
+
+                       mutex_lock(&als->lock);
+                       ulux = ulux * als->als_scale +
+                              div_u64(ulux * als->als_uscale, 1000000U);
+                       mutex_unlock(&als->lock);
+                       *val = div_u64(ulux, 1000000U);
+               } else {
+                       *val = temp_val;
+               }
+               return IIO_VAL_INT;
+       case IIO_CHAN_INFO_CALIBSCALE:
+               mutex_lock(&als->lock);
+               *val = als->als_scale;
+               *val2 = als->als_uscale;
+               mutex_unlock(&als->lock);
+               return IIO_VAL_INT_PLUS_MICRO;
+       default:
+               return -EINVAL;
+       }
+}
 
-       *val = temp_val;
+static int acpi_als_write_raw(struct iio_dev *iio,
+                             struct iio_chan_spec const *chan, int val,
+                             int val2, long mask)
+{
+       struct acpi_als *als = iio_priv(iio);
+
+       if (mask != IIO_CHAN_INFO_CALIBSCALE || chan->type != IIO_LIGHT)
+               return -EINVAL;
 
-       return IIO_VAL_INT;
+       mutex_lock(&als->lock);
+       als->als_scale = val;
+       als->als_uscale = val2;
+       mutex_unlock(&als->lock);
+       return 0;
 }
 
 static const struct iio_info acpi_als_info = {
        .driver_module          = THIS_MODULE,
        .read_raw               = acpi_als_read_raw,
+       .write_raw              = acpi_als_write_raw,
 };
 
 static int acpi_als_add(struct acpi_device *device)
@@ -189,6 +228,8 @@ static int acpi_als_add(struct acpi_device *device)
 
        device->driver_data = indio_dev;
        als->device = device;
+       als->als_scale = 1;
+       als->als_uscale = 0;
        mutex_init(&als->lock);
 
        indio_dev->name = ACPI_ALS_DEVICE_NAME;
-- 
2.1.0