hid.c

讲述linux的初始化过程

	for (i = 0; i < HID_REPORT_TYPES; i++) {
		struct hid_report_enum *report_enum = device->report_enum + i;

		for (j = 0; j < 256; j++) {
			struct hid_report *report = report_enum->report_id_hash[j];
			if (report) hid_free_report(report);
		}
	}

	if (device->rdesc) kfree(device->rdesc);
}

/*
 * Fetch a report description item from the data stream. We support long
 * items, though they are not used yet.
 */

static __u8 *fetch_item(__u8 *start, __u8 *end, struct hid_item *item)
{
	if ((end - start) > 0) {

		__u8 b = *start++;
		item->type = (b >> 2) & 3;
		item->tag  = (b >> 4) & 15;

		if (item->tag == HID_ITEM_TAG_LONG) {

			item->format = HID_ITEM_FORMAT_LONG;

			if ((end - start) >= 2) {

				item->size = *start++;
				item->tag  = *start++;

				if ((end - start) >= item->size) {
					item->data.longdata = start;
					start += item->size;
					return start;
				}
			}
		} else {

			item->format = HID_ITEM_FORMAT_SHORT;
			item->size = b & 3;
			switch (item->size) {

				case 0:
					return start;

				case 1: 
					if ((end - start) >= 1) {
						item->data.u8 = *start++;
						return start;
					}
					break;

				case 2: 
					if ((end - start) >= 2) {
						item->data.u16 = le16_to_cpu( get_unaligned(((__u16*)start)++));
						return start;
					}

				case 3: 
					item->size++;
					if ((end - start) >= 4) {
						item->data.u32 = le32_to_cpu( get_unaligned(((__u32*)start)++));
						return start;
					}
			}
		}
	}
	return NULL;
}

/*
 * Parse a report description into a hid_device structure. Reports are
 * enumerated, fields are attached to these reports.
 */

static struct hid_device *hid_parse_report(__u8 *start, unsigned size)
{
	struct hid_device *device;
	struct hid_parser *parser;
	struct hid_item    item;
	__u8 *end;
	unsigned i;
	static int (*dispatch_type[])(struct hid_parser *parser,
				      struct hid_item *item) = {
		hid_parser_main,
		hid_parser_global,
		hid_parser_local,
		hid_parser_reserved
	};

	if (!(device = kmalloc(sizeof(struct hid_device), GFP_KERNEL)))
		return NULL;
	memset(device, 0, sizeof(struct hid_device));

	for (i = 0; i < HID_REPORT_TYPES; i++)
		INIT_LIST_HEAD(&device->report_enum[i].report_list);

	if (!(device->rdesc = (__u8 *)kmalloc(size, GFP_KERNEL))) {
		kfree(device);
		return NULL;
	}
	memcpy(device->rdesc, start, size);

	if (!(parser = kmalloc(sizeof(struct hid_parser), GFP_KERNEL))) {
		kfree(device->rdesc);
		kfree(device);
		return NULL;
	}
	memset(parser, 0, sizeof(struct hid_parser));
	parser->device = device;
	
	end = start + size;
	while ((start = fetch_item(start, end, &item)) != 0) {
		if (item.format != HID_ITEM_FORMAT_SHORT) {
			dbg("unexpected long global item");
			hid_free_device(device);
			kfree(parser);
			return NULL;
		}
		if (dispatch_type[item.type](parser, &item)) {
			dbg("item %u %u %u %u parsing failed\n",
				item.format, (unsigned)item.size, (unsigned)item.type, (unsigned)item.tag);
			hid_free_device(device);
			kfree(parser);
			return NULL;
		}

		if (start == end) {
			if (parser->collection_stack_ptr) {
				dbg("unbalanced collection at end of report description");
				hid_free_device(device);
				kfree(parser);
				return NULL;
			}
			if (parser->local.delimiter_depth) {
				dbg("unbalanced delimiter at end of report description");
				hid_free_device(device);
				kfree(parser);
				return NULL;
			}
			kfree(parser);
			return device;
		}
	}

	dbg("item fetching failed at offset %d\n", (int)(end - start));
	hid_free_device(device);
	kfree(parser);
	return NULL;
}

/*
 * Convert a signed n-bit integer to signed 32-bit integer. Common
 * cases are done through the compiler, the screwed things has to be
 * done by hand.
 */

static __inline__ __s32 snto32(__u32 value, unsigned n)
{
	switch (n) {
		case 8:  return ((__s8)value);
		case 16: return ((__s16)value);
		case 32: return ((__s32)value);
	}
	return value & (1 << (n - 1)) ? value | (-1 << n) : value;
}

/*
 * Convert a signed 32-bit integer to a signed n-bit integer. 
 */

static __inline__ __u32 s32ton(__s32 value, unsigned n)
{
	__s32 a = value >> (n - 1);
	if (a && a != -1) return value > 0 ? 1 << (n - 1) : (1 << n) - 1;
	return value & ((1 << n) - 1);
}

/*
 * Extract/implement a data field from/to a report. We use 64-bit unsigned,
 * 32-bit aligned, so that we can possibly have alignment problems on some
 * odd architectures.
 */

static __inline__ __u32 extract(__u8 *report, unsigned offset, unsigned n)
{
	report += (offset >> 5) << 2; offset &= 31;
	return (le64_to_cpu(get_unaligned((__u64*)report)) >> offset) & ((1 << n) - 1);
}

static __inline__ void implement(__u8 *report, unsigned offset, unsigned n, __u32 value)
{
	report += (offset >> 5) << 2; offset &= 31;
	*(__u64*)report &= cpu_to_le64(~((((__u64) 1 << n) - 1) << offset));
	*(__u64*)report |= cpu_to_le64((__u64)value << offset);
}

static void hid_configure_usage(struct hid_device *device, struct hid_field *field, struct hid_usage *usage)
{
	struct input_dev *input = &device->input;
	int max;
	unsigned long *bit;

	switch (usage->hid & HID_USAGE_PAGE) {

		case HID_UP_KEYBOARD:

			set_bit(EV_REP, input->evbit);
			usage->type = EV_KEY; bit = input->keybit; max = KEY_MAX;

			if ((usage->hid & HID_USAGE) < 256) {
				if (!(usage->code = hid_keyboard[usage->hid & HID_USAGE]))
					return;
				clear_bit(usage->code, bit);
			} else
				usage->code = KEY_UNKNOWN;

			break; 

		case HID_UP_BUTTON:

			usage->code = ((usage->hid - 1) & 0xf) + 0x100;
			usage->type = EV_KEY; bit = input->keybit; max = KEY_MAX;
			
			switch (device->application) {
				case HID_GD_GAMEPAD:  usage->code += 0x10;
				case HID_GD_JOYSTICK: usage->code += 0x10;
				case HID_GD_MOUSE:    usage->code += 0x10; break;
				default:
					if (field->physical == HID_GD_POINTER)
						usage->code += 0x10;
					break;
			}
			break;

		case HID_UP_GENDESK:

			if ((usage->hid & 0xf0) == 0x80) {	/* SystemControl */
				switch (usage->hid & 0xf) {
					case 0x1: usage->code = KEY_POWER;  break;
					case 0x2: usage->code = KEY_SLEEP;  break;
					case 0x3: usage->code = KEY_WAKEUP; break;
					default: usage->code = KEY_UNKNOWN; break;
				}
				usage->type = EV_KEY; bit = input->keybit; max = KEY_MAX;
				break;
			}

			usage->code = usage->hid & 0xf;

			if (field->report_size == 1) {
				usage->code = BTN_MISC;
				usage->type = EV_KEY; bit = input->keybit; max = KEY_MAX;
				break;
			}

			if (field->flags & HID_MAIN_ITEM_RELATIVE) {
				usage->type = EV_REL; bit = input->relbit; max = REL_MAX;
				break;
			} 

			usage->type = EV_ABS; bit = input->absbit; max = ABS_MAX;

			if (usage->hid == HID_GD_HATSWITCH) {
				usage->code = ABS_HAT0X;
				usage->hat = 1 + (field->logical_maximum == 4);
			}
			break;

		case HID_UP_LED:

			usage->code = (usage->hid - 1) & 0xf;
			usage->type = EV_LED; bit = input->ledbit; max = LED_MAX; 
			break;

		case HID_UP_DIGITIZER:

			switch (usage->hid & 0xff) {

				case 0x30: /* TipPressure */

					if (!test_bit(BTN_TOUCH, input->keybit)) {
						device->quirks |= HID_QUIRK_NOTOUCH;
						set_bit(EV_KEY, input->evbit);
						set_bit(BTN_TOUCH, input->keybit);
					}
					usage->type = EV_ABS; bit = input->absbit; max = ABS_MAX; 
					usage->code = ABS_PRESSURE;
					clear_bit(usage->code, bit);
					break;

				case 0x32: /* InRange */

					usage->type = EV_KEY; bit = input->keybit; max = KEY_MAX;
					switch (field->physical & 0xff) {	
						case 0x21: usage->code = BTN_TOOL_MOUSE; break;
						case 0x22: usage->code = BTN_TOOL_FINGER; break;
						default: usage->code = BTN_TOOL_PEN; break;
					}
					break;

				case 0x3c: /* Invert */

					usage->type = EV_KEY; bit = input->keybit; max = KEY_MAX;
					usage->code = BTN_TOOL_RUBBER;
					clear_bit(usage->code, bit);
					break;

				case 0x33: /* Touch */
				case 0x42: /* TipSwitch */
				case 0x43: /* TipSwitch2 */

					device->quirks &= ~HID_QUIRK_NOTOUCH;
					usage->type = EV_KEY; bit = input->keybit; max = KEY_MAX;
					usage->code = BTN_TOUCH;
					clear_bit(usage->code, bit);
					break;

				case 0x44: /* BarrelSwitch */

					usage->type = EV_KEY; bit = input->keybit; max = KEY_MAX;
					usage->code = BTN_STYLUS;
					clear_bit(usage->code, bit);
					break;

				default:  goto unknown;
			}
			break;

		case HID_UP_CONSUMER:	/* USB HUT v1.1, pages 56-62 */
			
			switch (usage->hid & HID_USAGE) {
				case 0x000: usage->code = 0; break; 
				case 0x034: usage->code = KEY_SLEEP;		break;
				case 0x036: usage->code = BTN_MISC;		break;
				case 0x08a: usage->code = KEY_WWW;		break;
				case 0x095: usage->code = KEY_HELP;		break;

				case 0x0b4: usage->code = KEY_REWIND;		break;
				case 0x0b5: usage->code = KEY_NEXTSONG;		break;
				case 0x0b6: usage->code = KEY_PREVIOUSSONG;	break;
				case 0x0b7: usage->code = KEY_STOPCD;		break;
				case 0x0b8: usage->code = KEY_EJECTCD;		break;
				case 0x0cd: usage->code = KEY_PLAYPAUSE;	break;

				case 0x0e2: usage->code = KEY_MUTE;		break;
				case 0x0e9: usage->code = KEY_VOLUMEUP;		break;
				case 0x0ea: usage->code = KEY_VOLUMEDOWN;	break;

				case 0x183: usage->code = KEY_CONFIG;		break;
				case 0x18a: usage->code = KEY_MAIL;		break;
				case 0x192: usage->code = KEY_CALC;		break;
				case 0x194: usage->code = KEY_FILE;		break;

				case 0x21a: usage->code = KEY_UNDO;		break;
				case 0x21b: usage->code = KEY_COPY;		break;
				case 0x21c: usage->code = KEY_CUT;		break;
				case 0x21d: usage->code = KEY_PASTE;		break;

				case 0x221: usage->code = KEY_FIND;		break;
				case 0x223: usage->code = KEY_HOMEPAGE;		break;
				case 0x224: usage->code = KEY_BACK;		break;
				case 0x225: usage->code = KEY_FORWARD;		break;
				case 0x226: usage->code = KEY_STOP;		break;
				case 0x227: usage->code = KEY_REFRESH;		break;
				case 0x22a: usage->code = KEY_BOOKMARKS;	break;

				default:    usage->code = KEY_UNKNOWN;		break;

			}
		
			usage->type = EV_KEY; bit = input->keybit; max = KEY_MAX;
			break;

		default:
		unknown:

			if (field->report_size == 1) {
				usage->code = BTN_MISC;
				usage->type = EV_KEY; bit = input->keybit; max = KEY_MAX;
				break;
			}

			if (field->flags & HID_MAIN_ITEM_RELATIVE) {
				usage->code = REL_MISC;
				usage->type = EV_REL; bit = input->relbit; max = REL_MAX;
				break;
			}

			usage->code = ABS_MISC;
			usage->type = EV_ABS; bit = input->absbit; max = ABS_MAX;
			break;
	}

	set_bit(usage->type, input->evbit);

	while (usage->code <= max && test_and_set_bit(usage->code, bit)) {
		usage->code = find_next_zero_bit(bit, max + 1, usage->code);
	}

	if (usage->code > max) return;

	if (usage->type == EV_ABS) {
		int a = field->logical_minimum;
		int b = field->logical_maximum;

		input->absmin[usage->code] = a; 
		input->absmax[usage->code] = b;
		input->absfuzz[usage->code] = (b - a) >> 8;
		input->absflat[usage->code] = (b - a) >> 4;
	}

	if (usage->hat) {
		int i;
		for (i = usage->code; i < usage->code + 2 && i <= max; i++) {
			input->absmax[i] = 1;
			input->absmin[i] = -1;
			input->absfuzz[i] = 0;
			input->absflat[i] = 0;
		}
		set_bit(usage->code + 1, input->absbit);
	}
}

static void hid_process_event(struct input_dev *input, int *quirks, struct hid_field *field, struct hid_usage *usage, __s32 value)
{
	hid_dump_input(usage, value);

	if (usage->hat) {
		if (usage->hat == 2) value = value * 2;
		if (value > 8) value = 8;
		input_event(input, usage->type, usage->code    , hid_hat_to_axis[value].x);
		input_event(input, usage->type, usage->code + 1, hid_hat_to_axis[value].y);
		return;
	}

	if (usage->hid == (HID_UP_DIGITIZER | 0x003c)) { /* Invert */
		*quirks = value ? (*quirks | HID_QUIRK_INVERT) : (*quirks & ~HID_QUIRK_INVERT);
		return;
	}

	if (usage->hid == (HID_UP_DIGITIZER | 0x0032)) { /* InRange */
		if (value) {
			input_event(input, usage->type, (*quirks & HID_QUIRK_INVERT) ? BTN_TOOL_RUBBER : usage->code, 1);
			return;
		}
		input_event(input, usage->type, usage->code, 0);
		input_event(input, usage->type, BTN_TOOL_RUBBER, 0);
		return;
	}

	if (usage->hid == (HID_UP_DIGITIZER | 0x0030) && (*quirks & HID_QUIRK_NOTOUCH)) { /* Pressure */
		int a = field->logical_minimum;
		int b = field->logical_maximum;
		input_event(input, EV_KEY, BTN_TOUCH, value > a + ((b - a) >> 3));
	}

	if((usage->type == EV_KEY) && (usage->code == 0)) /* Key 0 is "unassigned", not KEY_UKNOWN */
		return;

	input_event(input, usage->type, usage->code, value);

	if ((field->flags & HID_MAIN_ITEM_RELATIVE) && (usage->type == EV_KEY))
		input_event(input, usage->type, usage->code, 0);
}

/*
 * Search an array for a value.
 */

static __inline__ int search(__s32 *array, __s32 value, unsigned n)
{
	while (n--) if (*array++ == value) return 0;
	return -1;
}

/*
 * Analyse a received field, and fetch the data from it. The field
 * content is stored for next report processing (we do differential
 * reporting to the layer).
 */

static void hid_input_field(struct hid_device *dev, struct hid_field *field, __u8 *data)
{
	unsigned n;
	unsigned count = field->report_count;
	unsigned offset = field->report_offset;
	unsigned size = field->report_size;
	__s32 min = field->logical_minimum;
	__s32 max = field->logical_maximum;
	__s32 value[count]; /* WARNING: gcc specific */
   
	for (n = 0; n < count; n++)
			value[n] = min < 0 ? snto32(extract(data, offset + n * size, size), size) : 
						    extract(data, offset + n * size, size);

	for (n = 0; n < count; n++) {

		if (HID_MAIN_ITEM_VARIABLE & field->flags) {

			if (field->flags & HID_MAIN_ITEM_RELATIVE) {
				if (!value[n]) continue;
			} else {
				if (value[n] == field->value[n]) continue;
			}
			hid_process_event(&dev->input, &dev->quirks, field, &field->usage[n], value[n]);

		} else {

			if (field->value[n] >= min && field->value[n] <= max			/* non-NULL value */
				&& field->usage[field->value[n] - min].hid			/* nonzero usage */
				&& search(value, field->value[n], count))
					hid_process_event(&dev->input, &dev->quirks, field,
						&field->usage[field->value[n] - min], 0);

			if (value[n] >= min && value[n] <= max					/* non-NULL value */