diff options
| -rw-r--r-- | drivers/hid/hid-core.c | 170 | ||||
| -rw-r--r-- | include/linux/hid.h | 5 |
2 files changed, 175 insertions, 0 deletions
diff --git a/drivers/hid/hid-core.c b/drivers/hid/hid-core.c index 43d488a45120..f41d5fe51abe 100644 --- a/drivers/hid/hid-core.c +++ b/drivers/hid/hid-core.c @@ -294,6 +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; @@ -947,6 +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 * @@ -1043,9 +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; } } diff --git a/include/linux/hid.h b/include/linux/hid.h index fdfda898656c..fd8d860365a4 100644 --- a/include/linux/hid.h +++ b/include/linux/hid.h @@ -219,6 +219,7 @@ struct hid_item { #define HID_GD_VBRZ 0x00010045 #define HID_GD_VNO 0x00010046 #define HID_GD_FEATURE 0x00010047 +#define HID_GD_RESOLUTION_MULTIPLIER 0x00010048 #define HID_GD_SYSTEM_CONTROL 0x00010080 #define HID_GD_UP 0x00010090 #define HID_GD_DOWN 0x00010091 @@ -437,6 +438,8 @@ struct hid_usage { unsigned hid; /* hid usage code */ unsigned collection_index; /* index into collection array */ unsigned usage_index; /* index into usage array */ + __s8 resolution_multiplier;/* Effective Resolution Multiplier + (HUT v1.12, 4.3.1), default: 1 */ /* hidinput data */ __u16 code; /* input driver code */ __u8 type; /* input driver type */ @@ -894,6 +897,8 @@ struct hid_report *hid_validate_values(struct hid_device *hid, unsigned int type, unsigned int id, unsigned int field_index, unsigned int report_counts); + +void hid_setup_resolution_multiplier(struct hid_device *hid); int hid_open_report(struct hid_device *device); int hid_check_keys_pressed(struct hid_device *hid); int hid_connect(struct hid_device *hid, unsigned int connect_mask); |