Added the ability for this driver to scan for a range of hid usage attributes.
This allows for dynamic creation of iio channels such as rotation from north
and/or magnetic flux axises (X, Y, Z).

Signed-off-by: Reyad Attiyat <reyad.atti...@gmail.com>
---
 drivers/iio/magnetometer/hid-sensor-magn-3d.c | 394 +++++++++++++++++---------
 1 file changed, 266 insertions(+), 128 deletions(-)

diff --git a/drivers/iio/magnetometer/hid-sensor-magn-3d.c 
b/drivers/iio/magnetometer/hid-sensor-magn-3d.c
index 41cf29e..73e1272 100644
--- a/drivers/iio/magnetometer/hid-sensor-magn-3d.c
+++ b/drivers/iio/magnetometer/hid-sensor-magn-3d.c
@@ -35,6 +35,10 @@ enum magn_3d_channel {
        CHANNEL_SCAN_INDEX_X,
        CHANNEL_SCAN_INDEX_Y,
        CHANNEL_SCAN_INDEX_Z,
+       CHANNEL_SCAN_INDEX_NORTH_MAGN,
+       CHANNEL_SCAN_INDEX_NORTH_TRUE,
+       CHANNEL_SCAN_INDEX_NORTH_MAGN_TILT_COMP,
+       CHANNEL_SCAN_INDEX_NORTH_TRUE_TILT_COMP,
        MAGN_3D_CHANNEL_MAX,
 };
 
@@ -42,63 +46,47 @@ struct magn_3d_state {
        struct hid_sensor_hub_callbacks callbacks;
        struct hid_sensor_common common_attributes;
        struct hid_sensor_hub_attribute_info magn[MAGN_3D_CHANNEL_MAX];
-       u32 magn_val[MAGN_3D_CHANNEL_MAX];
+       u32 *magn_val_addr[MAGN_3D_CHANNEL_MAX];
+       u32 *iio_val;
        int scale_pre_decml;
        int scale_post_decml;
        int scale_precision;
        int value_offset;
 };
 
-static const u32 magn_3d_addresses[MAGN_3D_CHANNEL_MAX] = {
-       HID_USAGE_SENSOR_ORIENT_MAGN_FLUX_X_AXIS,
-       HID_USAGE_SENSOR_ORIENT_MAGN_FLUX_Y_AXIS,
-       HID_USAGE_SENSOR_ORIENT_MAGN_FLUX_Z_AXIS
-};
 
-/* Channel definitions */
-static const struct iio_chan_spec magn_3d_channels[] = {
-       {
-               .type = IIO_MAGN,
-               .modified = 1,
-               .channel2 = IIO_MOD_X,
-               .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
-               .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_OFFSET) |
-               BIT(IIO_CHAN_INFO_SCALE) |
-               BIT(IIO_CHAN_INFO_SAMP_FREQ) |
-               BIT(IIO_CHAN_INFO_HYSTERESIS),
-               .scan_index = CHANNEL_SCAN_INDEX_X,
-       }, {
-               .type = IIO_MAGN,
-               .modified = 1,
-               .channel2 = IIO_MOD_Y,
-               .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
-               .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_OFFSET) |
-               BIT(IIO_CHAN_INFO_SCALE) |
-               BIT(IIO_CHAN_INFO_SAMP_FREQ) |
-               BIT(IIO_CHAN_INFO_HYSTERESIS),
-               .scan_index = CHANNEL_SCAN_INDEX_Y,
-       }, {
-               .type = IIO_MAGN,
-               .modified = 1,
-               .channel2 = IIO_MOD_Z,
-               .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
-               .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_OFFSET) |
-               BIT(IIO_CHAN_INFO_SCALE) |
-               BIT(IIO_CHAN_INFO_SAMP_FREQ) |
-               BIT(IIO_CHAN_INFO_HYSTERESIS),
-               .scan_index = CHANNEL_SCAN_INDEX_Z,
+/* Find index into magn_3d_state magn[] and magn_val_addr[] from HID Usage  */
+static int magn_3d_usage_id_to_chan_index(unsigned usage_id){
+       int offset;
+
+       switch (usage_id) {
+       case HID_USAGE_SENSOR_ORIENT_MAGN_FLUX_X_AXIS:
+               offset = CHANNEL_SCAN_INDEX_X;
+               break;
+       case HID_USAGE_SENSOR_ORIENT_MAGN_FLUX_Y_AXIS:
+               offset = CHANNEL_SCAN_INDEX_Y;
+               break;
+       case HID_USAGE_SENSOR_ORIENT_MAGN_FLUX_Z_AXIS:
+               offset = CHANNEL_SCAN_INDEX_Z;
+               break;
+       case HID_USAGE_SENSOR_ORIENT_COMP_MAGN_NORTH:
+               offset = CHANNEL_SCAN_INDEX_NORTH_MAGN_TILT_COMP;
+               break;
+       case HID_USAGE_SENSOR_ORIENT_COMP_TRUE_NORTH:
+               offset = CHANNEL_SCAN_INDEX_NORTH_TRUE_TILT_COMP;
+               break;
+       case HID_USAGE_SENSOR_ORIENT_MAGN_NORTH:
+               offset = CHANNEL_SCAN_INDEX_NORTH_MAGN;
+               break;
+       case HID_USAGE_SENSOR_ORIENT_TRUE_NORTH:
+               offset = CHANNEL_SCAN_INDEX_NORTH_TRUE;
+               break;
+       default:
+               offset = -EINVAL;
+               break;
        }
-};
 
-/* Adjust channel real bits based on report descriptor */
-static void magn_3d_adjust_channel_bit_mask(struct iio_chan_spec *channels,
-                                               int channel, int size)
-{
-       channels[channel].scan_type.sign = 's';
-       /* Real storage bits will change based on the report desc. */
-       channels[channel].scan_type.realbits = size * 8;
-       /* Maximum size of a sample to capture is u32 */
-       channels[channel].scan_type.storagebits = sizeof(u32) * 8;
+       return offset;
 }
 
 /* Channel read_raw handler */
@@ -109,11 +97,14 @@ static int magn_3d_read_raw(struct iio_dev *indio_dev,
 {
        struct magn_3d_state *magn_state = iio_priv(indio_dev);
        int report_id = -1;
-       u32 address;
+       unsigned usage_id;
+       int chan_index = -1;
        int ret;
        int ret_type;
        s32 poll_value;
 
+       dev_dbg(&indio_dev->dev, "magn_3d_read_raw\n");
+
        *val = 0;
        *val2 = 0;
        switch (mask) {
@@ -126,13 +117,17 @@ static int magn_3d_read_raw(struct iio_dev *indio_dev,
                hid_sensor_power_state(&magn_state->common_attributes, true);
                msleep_interruptible(poll_value * 2);
 
+               usage_id = chan->address;
+               chan_index = magn_3d_usage_id_to_chan_index(usage_id);
+               if (chan_index < 0)
+                       return -EINVAL;
+
                report_id =
-                       magn_state->magn[chan->scan_index].report_id;
-               address = magn_3d_addresses[chan->scan_index];
+                       magn_state->magn[chan_index].report_id;
                if (report_id >= 0)
                        *val = sensor_hub_input_attr_get_raw_value(
                                magn_state->common_attributes.hsdev,
-                               HID_USAGE_SENSOR_COMPASS_3D, address,
+                               HID_USAGE_SENSOR_COMPASS_3D, usage_id,
                                report_id);
                else {
                        *val = 0;
@@ -221,12 +216,13 @@ static int magn_3d_proc_event(struct 
hid_sensor_hub_device *hsdev,
        dev_dbg(&indio_dev->dev, "magn_3d_proc_event\n");
        if (atomic_read(&magn_state->common_attributes.data_ready))
                hid_sensor_push_data(indio_dev,
-                               magn_state->magn_val,
-                               sizeof(magn_state->magn_val));
+                               &(magn_state->iio_val),
+                               sizeof(magn_state->iio_val));
 
        return 0;
 }
 
+
 /* Capture samples in local storage */
 static int magn_3d_capture_sample(struct hid_sensor_hub_device *hsdev,
                                unsigned usage_id,
@@ -236,51 +232,138 @@ static int magn_3d_capture_sample(struct 
hid_sensor_hub_device *hsdev,
        struct iio_dev *indio_dev = platform_get_drvdata(priv);
        struct magn_3d_state *magn_state = iio_priv(indio_dev);
        int offset;
-       int ret = -EINVAL;
+       u32 *magn_val;
+       int ret = 0;
 
-       switch (usage_id) {
+       offset = magn_3d_usage_id_to_chan_index(usage_id);
+       if (offset < 0)
+               return -EINVAL;
+
+       magn_val = magn_state->magn_val_addr[offset];
+       if (!magn_val)
+               return -EINVAL;
+
+       *(magn_val) =  *(u32 *)raw_data;
+
+       return ret;
+}
+
+/* Setup the iio_chan_spec for HID Usage ID */
+static int magn_3d_setup_iio_chan(unsigned attr_usage_id,
+                               s32 size,
+                               struct iio_chan_spec *channel)
+{
+
+       channel->modified = 1;
+       channel->address = attr_usage_id;
+
+       switch (attr_usage_id){
+       case HID_USAGE_SENSOR_ORIENT_COMP_MAGN_NORTH:
+               channel->type = IIO_ROT;
+               channel->channel2 = IIO_MOD_NORTH_MAGN_TILT_COMP;
+               break;
+       case HID_USAGE_SENSOR_ORIENT_COMP_TRUE_NORTH:
+               channel->type = IIO_ROT;
+               channel->channel2 = IIO_MOD_NORTH_TRUE_TILT_COMP;
+               break;
+       case HID_USAGE_SENSOR_ORIENT_MAGN_NORTH:
+               channel->type = IIO_ROT;
+               channel->channel2 = IIO_MOD_NORTH_MAGN;
+               break;
+       case HID_USAGE_SENSOR_ORIENT_TRUE_NORTH:
+               channel->type = IIO_ROT;
+               channel->channel2 = IIO_MOD_NORTH_TRUE;
+               break;
        case HID_USAGE_SENSOR_ORIENT_MAGN_FLUX_X_AXIS:
+               channel->type = IIO_MAGN;
+               channel->channel2 = IIO_MOD_X;
+               break;
        case HID_USAGE_SENSOR_ORIENT_MAGN_FLUX_Y_AXIS:
+               channel->type = IIO_MAGN;
+               channel->channel2 = IIO_MOD_Y;
+               break;
        case HID_USAGE_SENSOR_ORIENT_MAGN_FLUX_Z_AXIS:
-               offset = usage_id - HID_USAGE_SENSOR_ORIENT_MAGN_FLUX_X_AXIS;
-               magn_state->magn_val[CHANNEL_SCAN_INDEX_X + offset] =
-                                               *(u32 *)raw_data;
-               ret = 0;
-       break;
-       default:
+               channel->type = IIO_MAGN;
+               channel->channel2 = IIO_MOD_Z;
                break;
+       default:
+               return -EINVAL;
        }
 
-       return ret;
+       channel->info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
+       channel->info_mask_shared_by_type =
+               BIT(IIO_CHAN_INFO_OFFSET) |
+               BIT(IIO_CHAN_INFO_SCALE) |
+               BIT(IIO_CHAN_INFO_SAMP_FREQ) |
+               BIT(IIO_CHAN_INFO_HYSTERESIS);
+
+       channel->scan_type.sign = 's';
+       /* Real storage bits will change based on the report desc. */
+       channel->scan_type.realbits = size  * 8;
+       /* Maximum size of a sample to capture is u32 */
+       channel->scan_type.storagebits = sizeof(u32) * 8;
+
+
+       return 0;
 }
 
-/* Parse report which is specific to an usage id*/
-static int magn_3d_parse_report(struct platform_device *pdev,
-                               struct hid_sensor_hub_device *hsdev,
-                               struct iio_chan_spec *channels,
+/* Scan a HID report for a range of attribute usages.
+ * Returns the count of attribute usages found.
+ */
+static int magn_3d_scan_range_usage_ids(struct hid_sensor_hub_device *hsdev,
                                unsigned usage_id,
+                               unsigned start_id,
+                               unsigned end_id,
                                struct magn_3d_state *st)
 {
+       int count = 0;
        int ret;
-       int i;
+       int id;
 
-       for (i = 0; i <= CHANNEL_SCAN_INDEX_Z; ++i) {
+       for (id = start_id; id <= end_id; id++) {
+               int i;
+
+               i = magn_3d_usage_id_to_chan_index(id);
+               if(i < 0)
+                       continue;
+
+               /* Check if usage attribute exists in the sensor hub device */
                ret = sensor_hub_input_get_attribute_info(hsdev,
                                HID_INPUT_REPORT,
                                usage_id,
-                               HID_USAGE_SENSOR_ORIENT_MAGN_FLUX_X_AXIS + i,
-                               &st->magn[CHANNEL_SCAN_INDEX_X + i]);
-               if (ret < 0)
-                       break;
-               magn_3d_adjust_channel_bit_mask(channels,
-                               CHANNEL_SCAN_INDEX_X + i,
-                               st->magn[CHANNEL_SCAN_INDEX_X + i].size);
+                               id,
+                               &(st->magn[i]));
+               if (ret == 0)
+                       count++;
+       }
+
+       return count;
+}
+
+/* Parse the HID report and return number of reports found */
+static int magn_3d_parse_report(struct platform_device *pdev,
+                               struct hid_sensor_hub_device *hsdev,
+                               unsigned usage_id,
+                               int* attribute_count,
+                               struct magn_3d_state *st)
+{
+       int usage_count = 0;
+
+       usage_count += magn_3d_scan_range_usage_ids(hsdev, usage_id,
+                                       HID_USAGE_SENSOR_ORIENT_COMP_MAGN_NORTH,
+                                       HID_USAGE_SENSOR_ORIENT_TRUE_NORTH,
+                                       st);
+
+       usage_count += magn_3d_scan_range_usage_ids(hsdev, usage_id,
+                                       
HID_USAGE_SENSOR_ORIENT_MAGN_FLUX_X_AXIS,
+                                       
HID_USAGE_SENSOR_ORIENT_MAGN_FLUX_Z_AXIS,
+                                       st);
+
+       if (attribute_count != NULL && usage_count > 0) {
+               *attribute_count = usage_count;
+       } else {
+               return -EINVAL;
        }
-       dev_dbg(&pdev->dev, "magn_3d %x:%x, %x:%x, %x:%x\n",
-                       st->magn[0].index,
-                       st->magn[0].report_id,
-                       st->magn[1].index, st->magn[1].report_id,
-                       st->magn[2].index, st->magn[2].report_id);
 
        st->scale_precision = hid_sensor_format_scale(
                                HID_USAGE_SENSOR_COMPASS_3D,
@@ -299,54 +382,60 @@ static int magn_3d_parse_report(struct platform_device 
*pdev,
                        st->common_attributes.sensitivity.report_id);
        }
 
-       return ret;
+       dev_dbg(&pdev->dev, "magn_3d_parse_reports found %d attribute 
usages\n", usage_count);
+
+       return 0;
 }
 
-/* Function to initialize the processing for usage id */
-static int hid_magn_3d_probe(struct platform_device *pdev)
+/* Setup iio channels */
+static int magn_3d_setup_iio_channels(struct platform_device *pdev,
+                               struct iio_dev *indio_dev,
+                               unsigned usage_id,
+                               int attr_count,
+                               struct magn_3d_state *st)
 {
-       int ret = 0;
+       int ret;
        static char *name = "magn_3d";
-       struct iio_dev *indio_dev;
-       struct magn_3d_state *magn_state;
-       struct hid_sensor_hub_device *hsdev = pdev->dev.platform_data;
        struct iio_chan_spec *channels;
+       int chan_count = 0;
+       int i;
 
-       indio_dev = devm_iio_device_alloc(&pdev->dev,
-                                         sizeof(struct magn_3d_state));
-       if (indio_dev == NULL)
+       /* Allocate IIO channels struct */
+       channels = devm_kcalloc(&pdev->dev,
+                       attr_count,
+                       sizeof(struct iio_chan_spec),
+                       GFP_KERNEL);
+       if (!channels) {
+               dev_err(&pdev->dev, "failed to allocate memory for iio 
channels\n");
                return -ENOMEM;
-
-       platform_set_drvdata(pdev, indio_dev);
-
-       magn_state = iio_priv(indio_dev);
-       magn_state->common_attributes.hsdev = hsdev;
-       magn_state->common_attributes.pdev = pdev;
-
-       ret = hid_sensor_parse_common_attributes(hsdev,
-                               HID_USAGE_SENSOR_COMPASS_3D,
-                               &magn_state->common_attributes);
-       if (ret) {
-               dev_err(&pdev->dev, "failed to setup common attributes\n");
-               return ret;
        }
 
-       channels = kmemdup(magn_3d_channels, sizeof(magn_3d_channels),
-                          GFP_KERNEL);
-       if (!channels) {
-               dev_err(&pdev->dev, "failed to duplicate channels\n");
+       /* Allocate IIO values array */
+       st->iio_val = devm_kcalloc(&pdev->dev,
+                               attr_count,
+                               sizeof(u32),
+                               GFP_KERNEL);
+       if (!(st->iio_val)) {
+               dev_err(&pdev->dev, "failed to allocate memory for iio 
value\n");
                return -ENOMEM;
        }
 
-       ret = magn_3d_parse_report(pdev, hsdev, channels,
-                               HID_USAGE_SENSOR_COMPASS_3D, magn_state);
-       if (ret) {
-               dev_err(&pdev->dev, "failed to setup attributes\n");
-               goto error_free_dev_mem;
+       /* Setup each IIO channel that is present */
+       for (i = 0; i < MAGN_3D_CHANNEL_MAX && chan_count < attr_count; i++){
+               u32 attr = st->magn[i].attrib_id;
+               s32 size = st->magn[i].size;
+
+               if (attr != 0 && size > 0) {
+                       ret = magn_3d_setup_iio_chan(attr, size, 
&(channels[chan_count]));
+                       if (ret == 0) {
+                               chan_count++;
+                               st->magn_val_addr[i] = 
&(st->iio_val[chan_count]);
+                       }
+               }
        }
 
        indio_dev->channels = channels;
-       indio_dev->num_channels = ARRAY_SIZE(magn_3d_channels);
+       indio_dev->num_channels = chan_count;
        indio_dev->dev.parent = &pdev->dev;
        indio_dev->info = &magn_3d_info;
        indio_dev->name = name;
@@ -358,9 +447,9 @@ static int hid_magn_3d_probe(struct platform_device *pdev)
                dev_err(&pdev->dev, "failed to initialize trigger buffer\n");
                goto error_free_dev_mem;
        }
-       atomic_set(&magn_state->common_attributes.data_ready, 0);
+       atomic_set(&st->common_attributes.data_ready, 0);
        ret = hid_sensor_setup_trigger(indio_dev, name,
-                                       &magn_state->common_attributes);
+                                       &st->common_attributes);
        if (ret < 0) {
                dev_err(&pdev->dev, "trigger setup failed\n");
                goto error_unreg_buffer_funcs;
@@ -372,6 +461,65 @@ static int hid_magn_3d_probe(struct platform_device *pdev)
                goto error_remove_trigger;
        }
 
+       return 0;
+
+error_remove_trigger:
+       hid_sensor_remove_trigger(&st->common_attributes);
+error_unreg_buffer_funcs:
+       iio_triggered_buffer_cleanup(indio_dev);
+error_free_dev_mem:
+       devm_kfree(&pdev->dev, (void*) indio_dev->channels);
+       devm_kfree(&pdev->dev, (void*) st->iio_val);
+
+       return -EINVAL;
+}
+
+/* Function to initialize the processing for usage id */
+static int hid_magn_3d_probe(struct platform_device *pdev)
+{
+       int ret;
+       struct iio_dev *indio_dev;
+       struct magn_3d_state *magn_state;
+       struct hid_sensor_hub_device *hsdev = pdev->dev.platform_data;
+       int report_attr_count = 0;
+
+       indio_dev = devm_iio_device_alloc(&pdev->dev,
+                                         sizeof(struct magn_3d_state));
+       if (indio_dev == NULL)
+               return -ENOMEM;
+
+       platform_set_drvdata(pdev, indio_dev);
+
+       magn_state = iio_priv(indio_dev);
+       magn_state->common_attributes.hsdev = hsdev;
+       magn_state->common_attributes.pdev = pdev;
+
+       ret = hid_sensor_parse_common_attributes(hsdev,
+                               HID_USAGE_SENSOR_COMPASS_3D,
+                               &magn_state->common_attributes);
+       if (ret) {
+               dev_err(&pdev->dev, "failed to setup common attributes\n");
+               return ret;
+       }
+
+       ret = magn_3d_parse_report(pdev, hsdev,
+                               HID_USAGE_SENSOR_COMPASS_3D,
+                               &report_attr_count,
+                               magn_state);
+       if (ret) {
+               dev_err(&pdev->dev, "failed to setup attributes\n");
+               return ret;
+       }
+
+       ret = magn_3d_setup_iio_channels(pdev, indio_dev,
+                               HID_USAGE_SENSOR_COMPASS_3D,
+                               report_attr_count,
+                               magn_state);
+       if (ret) {
+               dev_err(&pdev->dev, "failed to setup iio channel\n");
+               return ret;
+       }
+
        magn_state->callbacks.send_event = magn_3d_proc_event;
        magn_state->callbacks.capture_sample = magn_3d_capture_sample;
        magn_state->callbacks.pdev = pdev;
@@ -379,20 +527,9 @@ static int hid_magn_3d_probe(struct platform_device *pdev)
                                        &magn_state->callbacks);
        if (ret < 0) {
                dev_err(&pdev->dev, "callback reg failed\n");
-               goto error_iio_unreg;
        }
 
        return ret;
-
-error_iio_unreg:
-       iio_device_unregister(indio_dev);
-error_remove_trigger:
-       hid_sensor_remove_trigger(&magn_state->common_attributes);
-error_unreg_buffer_funcs:
-       iio_triggered_buffer_cleanup(indio_dev);
-error_free_dev_mem:
-       kfree(indio_dev->channels);
-       return ret;
 }
 
 /* Function to deinitialize the processing for usage id */
@@ -406,7 +543,8 @@ static int hid_magn_3d_remove(struct platform_device *pdev)
        iio_device_unregister(indio_dev);
        hid_sensor_remove_trigger(&magn_state->common_attributes);
        iio_triggered_buffer_cleanup(indio_dev);
-       kfree(indio_dev->channels);
+       devm_kfree(&pdev->dev, (void*) magn_state->iio_val);
+       devm_kfree(&pdev->dev, (void*) indio_dev->channels);
 
        return 0;
 }
-- 
1.9.3

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