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path: root/drivers/hid/hid-core.c
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Diffstat (limited to 'drivers/hid/hid-core.c')
-rw-r--r--drivers/hid/hid-core.c174
1 files changed, 174 insertions, 0 deletions
diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c
index 5bec9244c45b..f41d5fe51abe 100644
--- a/drivers/hid/hid-core.c
+++ b/drivers/hid/hid-core.c
@@ -172,6 +172,8 @@ static int open_collection(struct hid_parser *parser, unsigned type)
collection->type = type;
collection->usage = usage;
collection->level = parser->collection_stack_ptr - 1;
+ collection->parent = parser->active_collection;
+ parser->active_collection = collection;
if (type == HID_COLLECTION_APPLICATION)
parser->device->maxapplication++;
@@ -190,6 +192,8 @@ static int close_collection(struct hid_parser *parser)
return -EINVAL;
}
parser->collection_stack_ptr--;
+ if (parser->active_collection)
+ parser->active_collection = parser->active_collection->parent;
return 0;
}
@@ -290,6 +294,7 @@ static int hid_add_field(struct hid_parser *parser, unsigned report_type, unsign
field->usage[i].collection_index =
parser->local.collection_index[j];
field->usage[i].usage_index = i;
+ field->usage[i].resolution_multiplier = 1;
}
field->maxusage = usages;
@@ -943,6 +948,167 @@ struct hid_report *hid_validate_values(struct hid_device *hid,
}
EXPORT_SYMBOL_GPL(hid_validate_values);
+static int hid_calculate_multiplier(struct hid_device *hid,
+ struct hid_field *multiplier)
+{
+ int m;
+ __s32 v = *multiplier->value;
+ __s32 lmin = multiplier->logical_minimum;
+ __s32 lmax = multiplier->logical_maximum;
+ __s32 pmin = multiplier->physical_minimum;
+ __s32 pmax = multiplier->physical_maximum;
+
+ /*
+ * "Because OS implementations will generally divide the control's
+ * reported count by the Effective Resolution Multiplier, designers
+ * should take care not to establish a potential Effective
+ * Resolution Multiplier of zero."
+ * HID Usage Table, v1.12, Section 4.3.1, p31
+ */
+ if (lmax - lmin == 0)
+ return 1;
+ /*
+ * Handling the unit exponent is left as an exercise to whoever
+ * finds a device where that exponent is not 0.
+ */
+ m = ((v - lmin)/(lmax - lmin) * (pmax - pmin) + pmin);
+ if (unlikely(multiplier->unit_exponent != 0)) {
+ hid_warn(hid,
+ "unsupported Resolution Multiplier unit exponent %d\n",
+ multiplier->unit_exponent);
+ }
+
+ /* There are no devices with an effective multiplier > 255 */
+ if (unlikely(m == 0 || m > 255 || m < -255)) {
+ hid_warn(hid, "unsupported Resolution Multiplier %d\n", m);
+ m = 1;
+ }
+
+ return m;
+}
+
+static void hid_apply_multiplier_to_field(struct hid_device *hid,
+ struct hid_field *field,
+ struct hid_collection *multiplier_collection,
+ int effective_multiplier)
+{
+ struct hid_collection *collection;
+ struct hid_usage *usage;
+ int i;
+
+ /*
+ * If multiplier_collection is NULL, the multiplier applies
+ * to all fields in the report.
+ * Otherwise, it is the Logical Collection the multiplier applies to
+ * but our field may be in a subcollection of that collection.
+ */
+ for (i = 0; i < field->maxusage; i++) {
+ usage = &field->usage[i];
+
+ collection = &hid->collection[usage->collection_index];
+ while (collection && collection != multiplier_collection)
+ collection = collection->parent;
+
+ if (collection || multiplier_collection == NULL)
+ usage->resolution_multiplier = effective_multiplier;
+
+ }
+}
+
+static void hid_apply_multiplier(struct hid_device *hid,
+ struct hid_field *multiplier)
+{
+ struct hid_report_enum *rep_enum;
+ struct hid_report *rep;
+ struct hid_field *field;
+ struct hid_collection *multiplier_collection;
+ int effective_multiplier;
+ int i;
+
+ /*
+ * "The Resolution Multiplier control must be contained in the same
+ * Logical Collection as the control(s) to which it is to be applied.
+ * If no Resolution Multiplier is defined, then the Resolution
+ * Multiplier defaults to 1. If more than one control exists in a
+ * Logical Collection, the Resolution Multiplier is associated with
+ * all controls in the collection. If no Logical Collection is
+ * defined, the Resolution Multiplier is associated with all
+ * controls in the report."
+ * HID Usage Table, v1.12, Section 4.3.1, p30
+ *
+ * Thus, search from the current collection upwards until we find a
+ * logical collection. Then search all fields for that same parent
+ * collection. Those are the fields the multiplier applies to.
+ *
+ * If we have more than one multiplier, it will overwrite the
+ * applicable fields later.
+ */
+ multiplier_collection = &hid->collection[multiplier->usage->collection_index];
+ while (multiplier_collection &&
+ multiplier_collection->type != HID_COLLECTION_LOGICAL)
+ multiplier_collection = multiplier_collection->parent;
+
+ effective_multiplier = hid_calculate_multiplier(hid, multiplier);
+
+ rep_enum = &hid->report_enum[HID_INPUT_REPORT];
+ list_for_each_entry(rep, &rep_enum->report_list, list) {
+ for (i = 0; i < rep->maxfield; i++) {
+ field = rep->field[i];
+ hid_apply_multiplier_to_field(hid, field,
+ multiplier_collection,
+ effective_multiplier);
+ }
+ }
+}
+
+/*
+ * hid_setup_resolution_multiplier - set up all resolution multipliers
+ *
+ * @device: hid device
+ *
+ * Search for all Resolution Multiplier Feature Reports and apply their
+ * value to all matching Input items. This only updates the internal struct
+ * fields.
+ *
+ * The Resolution Multiplier is applied by the hardware. If the multiplier
+ * is anything other than 1, the hardware will send pre-multiplied events
+ * so that the same physical interaction generates an accumulated
+ * accumulated_value = value * * multiplier
+ * This may be achieved by sending
+ * - "value * multiplier" for each event, or
+ * - "value" but "multiplier" times as frequently, or
+ * - a combination of the above
+ * The only guarantee is that the same physical interaction always generates
+ * an accumulated 'value * multiplier'.
+ *
+ * This function must be called before any event processing and after
+ * any SetRequest to the Resolution Multiplier.
+ */
+void hid_setup_resolution_multiplier(struct hid_device *hid)
+{
+ struct hid_report_enum *rep_enum;
+ struct hid_report *rep;
+ struct hid_usage *usage;
+ int i, j;
+
+ rep_enum = &hid->report_enum[HID_FEATURE_REPORT];
+ list_for_each_entry(rep, &rep_enum->report_list, list) {
+ for (i = 0; i < rep->maxfield; i++) {
+ /* Ignore if report count is out of bounds. */
+ if (rep->field[i]->report_count < 1)
+ continue;
+
+ for (j = 0; j < rep->field[i]->maxusage; j++) {
+ usage = &rep->field[i]->usage[j];
+ if (usage->hid == HID_GD_RESOLUTION_MULTIPLIER)
+ hid_apply_multiplier(hid,
+ rep->field[i]);
+ }
+ }
+ }
+}
+EXPORT_SYMBOL_GPL(hid_setup_resolution_multiplier);
+
/**
* hid_open_report - open a driver-specific device report
*
@@ -1039,9 +1205,17 @@ int hid_open_report(struct hid_device *device)
hid_err(device, "unbalanced delimiter at end of report description\n");
goto err;
}
+
+ /*
+ * fetch initial values in case the device's
+ * default multiplier isn't the recommended 1
+ */
+ hid_setup_resolution_multiplier(device);
+
kfree(parser->collection_stack);
vfree(parser);
device->status |= HID_STAT_PARSED;
+
return 0;
}
}