hid-core.c

基于S3CEB2410平台LINUX操作系统下 USB驱动源代码

				if (hid_add_usage(parser, n)) {
					dbg("hid_add_usage failed\n");
					return -1;
				}
			return 0;

		default:

			dbg("unknown local item tag 0x%x", item->tag);
			return 0;
	}
	return 0;
}

/*
 * Process a main item.
 */

static int hid_parser_main(struct hid_parser *parser, struct hid_item *item)
{
	__u32 data;
	int ret;

	data = item_udata(item);

	switch (item->tag) {
		case HID_MAIN_ITEM_TAG_BEGIN_COLLECTION:
			ret = open_collection(parser, data & 3);
			break;
		case HID_MAIN_ITEM_TAG_END_COLLECTION:
			ret = close_collection(parser);
			break;
		case HID_MAIN_ITEM_TAG_INPUT:
			ret = hid_add_field(parser, HID_INPUT_REPORT, data);
			break;
		case HID_MAIN_ITEM_TAG_OUTPUT:
			ret = hid_add_field(parser, HID_OUTPUT_REPORT, data);
			break;
		case HID_MAIN_ITEM_TAG_FEATURE:
			ret = hid_add_field(parser, HID_FEATURE_REPORT, data);
			break;
		default:
			dbg("unknown main item tag 0x%x", item->tag);
			ret = 0;
	}

	memset(&parser->local, 0, sizeof(parser->local));	/* Reset the local parser environment */

	return ret;
}

/*
 * Process a reserved item.
 */

static int hid_parser_reserved(struct hid_parser *parser, struct hid_item *item)
{
	dbg("reserved item type, tag 0x%x", item->tag);
	return 0;
}

/*
 * Free a report and all registered fields. The field->usage and
 * field->value table's are allocated behind the field, so we need
 * only to free(field) itself.
 */

static void hid_free_report(struct hid_report *report)
{
	unsigned n;

	for (n = 0; n < report->maxfield; n++)
		kfree(report->field[n]);
	if (report->data)
		kfree(report->data);
	kfree(report);
}

/*
 * Free a device structure, all reports, and all fields.
 */

static void hid_free_device(struct hid_device *device)
{
	unsigned i,j;

	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)) - 1;
	return value & ((1 << n) - 1);
}

/*
 * Extract/implement a data field from/to a report.
 */

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;
	put_unaligned((get_unaligned((__u64*)report)
		& cpu_to_le64(~((((__u64) 1 << n) - 1) << offset)))
		| cpu_to_le64((__u64)value << offset), (__u64*)report);
}

/*
 * 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;
}

static void hid_process_event(struct hid_device *hid, struct hid_field *field, struct hid_usage *usage, __s32 value)
{
	hid_dump_input(usage, value);
	if (hid->claimed & HID_CLAIMED_INPUT)
		hidinput_hid_event(hid, field, usage, value);
#ifdef CONFIG_USB_HIDDEV
	if (hid->claimed & HID_CLAIMED_HIDDEV)
		hiddev_hid_event(hid, usage->hid, value);
#endif
}


/*
 * 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 *hid, 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);

			if (!(field->flags & HID_MAIN_ITEM_VARIABLE) /* Ignore report if ErrorRollOver */
			    && value[n] >= min && value[n] <= max
			    && field->usage[value[n] - min].hid == HID_UP_KEYBOARD + 1)
				return;
	}

	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(hid, field, &field->usage[n], value[n]);
			continue;
		}

		if (field->value[n] >= min && field->value[n] <= max
			&& field->usage[field->value[n] - min].hid
			&& search(value, field->value[n], count))
				hid_process_event(hid, field, &field->usage[field->value[n] - min], 0);

		if (value[n] >= min && value[n] <= max
			&& field->usage[value[n] - min].hid
			&& search(field->value, value[n], count))
				hid_process_event(hid, field, &field->usage[value[n] - min], 1);
	}

	memcpy(field->value, value, count * sizeof(__s32));
}

static int hid_input_report(int type, u8 *data, int len, struct hid_device *hid)
{
	struct hid_report_enum *report_enum = hid->report_enum + type;
	struct hid_report *report;
	int n, size;

	if (!len) {
		dbg("empty report");
		return -1;
	}

#ifdef DEBUG_DATA
	printk(KERN_DEBUG __FILE__ ": report (size %u) (%snumbered)\n", len, report_enum->numbered ? "" : "un");
#endif

	n = 0;				/* Normally report number is 0 */
	if (report_enum->numbered) {	/* Device uses numbered reports, data[0] is report number */
		n = *data++;
		len--;
	}

	if (!(report = report_enum->report_id_hash[n])) {
		dbg("undefined report_id %d received", n);
#ifdef DEBUG
			printk(KERN_DEBUG __FILE__ ": report (size %u) = ", len);
			for (n = 0; n < len; n++)
				printk(" %02x", data[n]);
			printk("\n");
#endif

		return -1;
	}

	size = ((report->size - 1) >> 3) + 1;

	if (len < size) {

		if (size <= 8) {
			dbg("report %d is too short, (%d < %d)", report->id, len, size);
			return -1;
		}

		/*
		 * Some low-speed devices have large reports and maxpacketsize 8.
		 * We buffer the data in that case and parse it when we got it all.
		 * Works only for unnumbered reports. Doesn't make sense for numbered
		 * reports anyway - then they don't need to be large.
		 */

		if (!report->data)
			if (!(report->data = kmalloc(size, GFP_ATOMIC))) {
				dbg("couldn't allocate report buffer");
				return -1;
			}

		if (report->idx + len > size) {
			dbg("report data buffer overflow");
			report->idx = 0;
			return -1;
		}

		memcpy(report->data + report->idx, data, len);
		report->idx += len;

		if (report->idx < size)
			return 0;

		data = report->data;
	}

	for (n = 0; n < report->maxfield; n++)
		hid_input_field(hid, report->field[n], data);

	report->idx = 0;