1 // SPDX-License-Identifier: GPL-2.0-only
3  *   Copyright (C) 2016 T-Platforms. All Rights Reserved.
5  * IDT PCIe-switch NTB Linux driver
8  * Serge Semin <fancer.lancer@gmail.com>, <Sergey.Semin@t-platforms.ru>
11  *           NOTE of the IDT 89HPESx SMBus-slave interface driver
13  * IDT PCIe-switches. IDT provides a simple SMBus interface to perform IO-
16  * binary sysfs-file in the device directory:
17  * /sys/bus/i2c/devices/<bus>-<devaddr>/eeprom
18  * In case if read-only flag is specified in the dts-node of device desription,
19  * User-space applications won't be able to write to the EEPROM sysfs-node.
21  * data of device CSRs. This driver exposes debugf-file to perform simple IO
23  * next file is created in the specific debugfs-directory:
25  * Format of the debugfs-node is:
26  * $ cat /sys/kernel/debug/idt_csr/<bus>-<devaddr>/<devname>;
29  * If User-space application wishes to change current CSR address,
30  * it can just write a proper value to the sysfs-file:
31  * $ echo "<CSR address>" > /sys/kernel/debug/idt_csr/<bus>-<devaddr>/<devname>
35  *        /sys/kernel/debug/idt_csr/<bus>-<devaddr>/<devname>;
50 #include <linux/i2c.h>
55 #define IDT_89HPESX_DESC	"IDT 89HPESx SMBus-slave interface driver"
61 MODULE_AUTHOR("T-platforms");
64  * csr_dbgdir - CSR read/write operations Debugfs directory
69  * struct idt_89hpesx_dev - IDT 89HPESx device data structure
71  * @eero:	EEPROM Read-only flag
76  * @iniccode:	Initialial command code value for IO-operations
84  * @client:	i2c client used to perform IO operations
86  * @ee_file:	EEPROM read/write sysfs-file
111  * struct idt_smb_seq - sequence of data to be read/written from/to IDT 89HPESx
113  * @bytecnt:	Byte count of operation
123  * struct idt_eeprom_seq - sequence of data to be read/written from/to EEPROM
137  * struct idt_csr_seq - sequence of data to be read/written from/to CSR
176  * @EEPROM_WR_CNT:	Bytes count to perform write operation
177  * @EEPROM_WRRD_CNT:	Bytes count to write before reading
178  * @EEPROM_RD_CNT:	Bytes count to perform read operation
181  * @EEPROM_TOUT:	Timeout before retry read operation if eeprom is busy
203  * @CSR_WR_CNT:		Bytes count to perform write operation
204  * @CSR_WRRD_CNT:	Bytes count to write before reading
205  * @CSR_RD_CNT:		Bytes count to perform read operation
235  * @idt_smb_safe:	Generate a retry loop on corresponding SMBus method
243 	} while (__retry-- && __sts < 0); \
248  *                         i2c bus level IO-operations
253  * idt_smb_write_byte() - SMBus write method when I2C_SMBUS_BYTE_DATA operation
265 	/* Loop over the supplied data sending byte one-by-one */  in idt_smb_write_byte()
266 	for (idx = 0; idx < seq->bytecnt; idx++) {  in idt_smb_write_byte()
268 		ccode = seq->ccode | CCODE_BYTE;  in idt_smb_write_byte()
271 		if (idx == seq->bytecnt - 1)  in idt_smb_write_byte()
275 		sts = idt_smb_safe(write_byte, pdev->client, ccode,  in idt_smb_write_byte()
276 			seq->data[idx]);  in idt_smb_write_byte()
285  * idt_smb_read_byte() - SMBus read method when I2C_SMBUS_BYTE_DATA operation
297 	/* Loop over the supplied buffer receiving byte one-by-one */  in idt_smb_read_byte()
298 	for (idx = 0; idx < seq->bytecnt; idx++) {  in idt_smb_read_byte()
300 		ccode = seq->ccode | CCODE_BYTE;  in idt_smb_read_byte()
303 		if (idx == seq->bytecnt - 1)  in idt_smb_read_byte()
307 		sts = idt_smb_safe(read_byte, pdev->client, ccode);  in idt_smb_read_byte()
311 		seq->data[idx] = (u8)sts;  in idt_smb_read_byte()
318  * idt_smb_write_word() - SMBus write method when I2C_SMBUS_BYTE_DATA and
330 	/* Calculate the even count of data to send */  in idt_smb_write_word()
331 	evencnt = seq->bytecnt - (seq->bytecnt % 2);  in idt_smb_write_word()
336 		ccode = seq->ccode | CCODE_WORD;  in idt_smb_write_word()
339 		if (idx == evencnt - 2)  in idt_smb_write_word()
343 		sts = idt_smb_safe(write_word, pdev->client, ccode,  in idt_smb_write_word()
344 			*(u16 *)&seq->data[idx]);  in idt_smb_write_word()
350 	if (seq->bytecnt != evencnt) {  in idt_smb_write_word()
352 		ccode = seq->ccode | CCODE_BYTE | CCODE_END;  in idt_smb_write_word()
357 		sts = idt_smb_safe(write_byte, pdev->client, ccode,  in idt_smb_write_word()
358 			seq->data[idx]);  in idt_smb_write_word()
367  * idt_smb_read_word() - SMBus read method when I2C_SMBUS_BYTE_DATA and
379 	/* Calculate the even count of data to send */  in idt_smb_read_word()
380 	evencnt = seq->bytecnt - (seq->bytecnt % 2);  in idt_smb_read_word()
385 		ccode = seq->ccode | CCODE_WORD;  in idt_smb_read_word()
388 		if (idx == evencnt - 2)  in idt_smb_read_word()
392 		sts = idt_smb_safe(read_word, pdev->client, ccode);  in idt_smb_read_word()
396 		*(u16 *)&seq->data[idx] = (u16)sts;  in idt_smb_read_word()
400 	if (seq->bytecnt != evencnt) {  in idt_smb_read_word()
402 		ccode = seq->ccode | CCODE_BYTE | CCODE_END;  in idt_smb_read_word()
407 		sts = idt_smb_safe(read_byte, pdev->client, ccode);  in idt_smb_read_word()
411 		seq->data[idx] = (u8)sts;  in idt_smb_read_word()
418  * idt_smb_write_block() - SMBus write method when I2C_SMBUS_BLOCK_DATA
429 	if (seq->bytecnt > I2C_SMBUS_BLOCK_MAX)  in idt_smb_write_block()
430 		return -EINVAL;  in idt_smb_write_block()
433 	ccode = seq->ccode | CCODE_BLOCK | CCODE_START | CCODE_END;  in idt_smb_write_block()
436 	return idt_smb_safe(write_block, pdev->client, ccode, seq->bytecnt,  in idt_smb_write_block()
437 		seq->data);  in idt_smb_write_block()
441  * idt_smb_read_block() - SMBus read method when I2C_SMBUS_BLOCK_DATA
453 	if (seq->bytecnt > I2C_SMBUS_BLOCK_MAX)  in idt_smb_read_block()
454 		return -EINVAL;  in idt_smb_read_block()
457 	ccode = seq->ccode | CCODE_BLOCK | CCODE_START | CCODE_END;  in idt_smb_read_block()
460 	sts = idt_smb_safe(read_block, pdev->client, ccode, seq->data);  in idt_smb_read_block()
461 	if (sts != seq->bytecnt)  in idt_smb_read_block()
462 		return (sts < 0 ? sts : -ENODATA);  in idt_smb_read_block()
468  * idt_smb_write_i2c_block() - SMBus write method when I2C_SMBUS_I2C_BLOCK_DATA
482 	if (seq->bytecnt > I2C_SMBUS_BLOCK_MAX)  in idt_smb_write_i2c_block()
483 		return -EINVAL;  in idt_smb_write_i2c_block()
486 	buf[0] = seq->bytecnt;  in idt_smb_write_i2c_block()
487 	memcpy(&buf[1], seq->data, seq->bytecnt);  in idt_smb_write_i2c_block()
490 	ccode = seq->ccode | CCODE_BLOCK | CCODE_START | CCODE_END;  in idt_smb_write_i2c_block()
493 	return idt_smb_safe(write_i2c_block, pdev->client, ccode,  in idt_smb_write_i2c_block()
494 		seq->bytecnt + 1, buf);  in idt_smb_write_i2c_block()
498  * idt_smb_read_i2c_block() - SMBus read method when I2C_SMBUS_I2C_BLOCK_DATA
513 	if (seq->bytecnt > I2C_SMBUS_BLOCK_MAX)  in idt_smb_read_i2c_block()
514 		return -EINVAL;  in idt_smb_read_i2c_block()
517 	ccode = seq->ccode | CCODE_BLOCK | CCODE_START | CCODE_END;  in idt_smb_read_i2c_block()
520 	sts = idt_smb_safe(read_i2c_block, pdev->client, ccode,  in idt_smb_read_i2c_block()
521 		seq->bytecnt + 1, buf);  in idt_smb_read_i2c_block()
522 	if (sts != seq->bytecnt + 1)  in idt_smb_read_i2c_block()
523 		return (sts < 0 ? sts : -ENODATA);  in idt_smb_read_i2c_block()
524 	if (buf[0] != seq->bytecnt)  in idt_smb_read_i2c_block()
525 		return -ENODATA;  in idt_smb_read_i2c_block()
528 	memcpy(seq->data, &buf[1], seq->bytecnt);  in idt_smb_read_i2c_block()
534  *                          EEPROM IO-operations
539  * idt_eeprom_read_byte() - read just one byte from EEPROM
547 	struct device *dev = &pdev->client->dev;  in idt_eeprom_read_byte()
550 	int ret, retry;  in idt_eeprom_read_byte()  local
553 	smbseq.ccode = pdev->iniccode | CCODE_EEPROM;  in idt_eeprom_read_byte()
560 	retry = RETRY_CNT;  in idt_eeprom_read_byte()
564 		eeseq.cmd = pdev->inieecmd | EEPROM_OP_READ;  in idt_eeprom_read_byte()
565 		eeseq.eeaddr = pdev->eeaddr;  in idt_eeprom_read_byte()
567 		ret = pdev->smb_write(pdev, &smbseq);  in idt_eeprom_read_byte()
576 		ret = pdev->smb_read(pdev, &smbseq);  in idt_eeprom_read_byte()
584 		if (retry && (eeseq.cmd & EEPROM_NAERR)) {  in idt_eeprom_read_byte()
585 			dev_dbg(dev, "EEPROM busy, retry reading after %d ms",  in idt_eeprom_read_byte()
596 			ret = -EREMOTEIO;  in idt_eeprom_read_byte()
603 	} while (retry--);  in idt_eeprom_read_byte()
610  * idt_eeprom_write() - EEPROM write operation
619 	struct device *dev = &pdev->client->dev;  in idt_eeprom_write()
626 	smbseq.ccode = pdev->iniccode | CCODE_EEPROM;  in idt_eeprom_write()
629 	/* Send data byte-by-byte, checking if it is successfully written */  in idt_eeprom_write()
632 		mutex_lock(&pdev->smb_mtx);  in idt_eeprom_write()
636 		eeseq.cmd = pdev->inieecmd | EEPROM_OP_WRITE;  in idt_eeprom_write()
637 		eeseq.eeaddr = pdev->eeaddr;  in idt_eeprom_write()
640 		ret = pdev->smb_write(pdev, &smbseq);  in idt_eeprom_write()
661 			ret = -EREMOTEIO;  in idt_eeprom_write()
667 		mutex_unlock(&pdev->smb_mtx);  in idt_eeprom_write()
676  * idt_eeprom_read() - EEPROM read operation
688 	/* Read data byte-by-byte, retrying if it wasn't successful */  in idt_eeprom_read()
691 		mutex_lock(&pdev->smb_mtx);  in idt_eeprom_read()
697 		mutex_unlock(&pdev->smb_mtx);  in idt_eeprom_read()
708  *                          CSR IO-operations
713  * idt_csr_write() - CSR write operation
721 	struct device *dev = &pdev->client->dev;  in idt_csr_write()
727 	smbseq.ccode = pdev->iniccode | CCODE_CSR;  in idt_csr_write()
731 	mutex_lock(&pdev->smb_mtx);  in idt_csr_write()
735 	csrseq.cmd = pdev->inicsrcmd | CSR_OP_WRITE;  in idt_csr_write()
738 	ret = pdev->smb_write(pdev, &smbseq);  in idt_csr_write()
747 	csrseq.cmd = pdev->inicsrcmd | CSR_OP_READ;  in idt_csr_write()
748 	ret = pdev->smb_write(pdev, &smbseq);  in idt_csr_write()
757 	ret = pdev->smb_read(pdev, &smbseq);  in idt_csr_write()
767 		ret = -EREMOTEIO;  in idt_csr_write()
773 	mutex_unlock(&pdev->smb_mtx);  in idt_csr_write()
779  * idt_csr_read() - CSR read operation
786 	struct device *dev = &pdev->client->dev;  in idt_csr_read()
792 	smbseq.ccode = pdev->iniccode | CCODE_CSR;  in idt_csr_read()
796 	mutex_lock(&pdev->smb_mtx);  in idt_csr_read()
800 	csrseq.cmd = pdev->inicsrcmd | CSR_OP_READ;  in idt_csr_read()
802 	ret = pdev->smb_write(pdev, &smbseq);  in idt_csr_read()
811 	ret = pdev->smb_read(pdev, &smbseq);  in idt_csr_read()
821 		ret = -EREMOTEIO;  in idt_csr_read()
830 	mutex_unlock(&pdev->smb_mtx);  in idt_csr_read()
836  *                          Sysfs/debugfs-nodes IO-operations
841  * eeprom_write() - EEPROM sysfs-node write callback
843  * @kobj:	Pointer to the kernel object related to the sysfs-node
847  * @count:	Number of bytes to write
851 			    char *buf, loff_t off, size_t count)  in eeprom_write()  argument
860 	ret = idt_eeprom_write(pdev, (u16)off, (u16)count, (u8 *)buf);  in eeprom_write()
861 	return (ret != 0 ? ret : count);  in eeprom_write()
865  * eeprom_read() - EEPROM sysfs-node read callback
867  * @kobj:	Pointer to the kernel object related to the sysfs-node
871  * @count:	Number of bytes to write
875 			   char *buf, loff_t off, size_t count)  in eeprom_read()  argument
884 	ret = idt_eeprom_read(pdev, (u16)off, (u16)count, (u8 *)buf);  in eeprom_read()
885 	return (ret != 0 ? ret : count);  in eeprom_read()
889  * idt_dbgfs_csr_write() - CSR debugfs-node write callback
892  * @count:	Size of the buffer
904 				   size_t count, loff_t *offp)  in idt_dbgfs_csr_write()  argument
906 	struct idt_89hpesx_dev *pdev = filep->private_data;  in idt_dbgfs_csr_write()
915 	/* Copy data from User-space */  in idt_dbgfs_csr_write()
916 	buf = memdup_user_nul(ubuf, count);  in idt_dbgfs_csr_write()
921 	colon_ch = strnchr(buf, count, ':');  in idt_dbgfs_csr_write()
931 		csraddr_str = kmemdup_nul(buf, colon_ch - buf, GFP_KERNEL);  in idt_dbgfs_csr_write()
933 			ret = -ENOMEM;  in idt_dbgfs_csr_write()
950 		ret = -EINVAL;  in idt_dbgfs_csr_write()
955 	pdev->csr = (csraddr >> 2);  in idt_dbgfs_csr_write()
963 		ret = idt_csr_write(pdev, pdev->csr, csrval);  in idt_dbgfs_csr_write()
973 	/* Free buffer allocated for data retrieved from User-space */  in idt_dbgfs_csr_write()
977 	return (ret != 0 ? ret : count);  in idt_dbgfs_csr_write()
981  * idt_dbgfs_csr_read() - CSR debugfs-node read callback
984  * @count:	Size of the buffer
991 				  size_t count, loff_t *offp)  in idt_dbgfs_csr_read()  argument
993 	struct idt_89hpesx_dev *pdev = filep->private_data;  in idt_dbgfs_csr_read()
999 	ret = idt_csr_read(pdev, pdev->csr, &csrval);  in idt_dbgfs_csr_read()
1004 	csraddr = ((u32)pdev->csr << 2);  in idt_dbgfs_csr_read()
1010 	/* Copy data to User-space */  in idt_dbgfs_csr_read()
1011 	return simple_read_from_buffer(ubuf, count, offp, buf, size);  in idt_dbgfs_csr_read()
1015  * eeprom_attribute - EEPROM sysfs-node attributes
1018  * be read-only as well if the corresponding flag is specified in OF node.
1023  * csr_dbgfs_ops - CSR debugfs-node read/write operations
1038  * idt_set_defval() - disable EEPROM access by default
1044 	pdev->eesize = 0;  in idt_set_defval()
1045 	pdev->eero = true;  in idt_set_defval()
1046 	pdev->inieecmd = 0;  in idt_set_defval()
1047 	pdev->eeaddr = 0;  in idt_set_defval()
1053  * idt_ee_match_id() - check whether the node belongs to compatible EEPROMs
1069 	while (id->name[0]) {  in idt_ee_match_id()
1070 		if (strcmp(devname, id->name) == 0)  in idt_ee_match_id()
1078  * idt_get_fw_data() - get IDT i2c-device parameters from device tree
1083 	struct device *dev = &pdev->client->dev;  in idt_get_fw_data()
1105 	pdev->eesize = (u32)ee_id->driver_data;  in idt_get_fw_data()
1112 		pdev->inieecmd = 0;  in idt_get_fw_data()
1113 		pdev->eeaddr = EEPROM_DEF_ADDR << 1;  in idt_get_fw_data()
1115 		pdev->inieecmd = EEPROM_USA;  in idt_get_fw_data()
1116 		pdev->eeaddr = eeprom_addr << 1;  in idt_get_fw_data()
1119 	/* Check EEPROM 'read-only' flag */  in idt_get_fw_data()
1120 	if (fwnode_property_read_bool(fwnode, "read-only"))  in idt_get_fw_data()
1121 		pdev->eero = true;  in idt_get_fw_data()
1122 	else /* if (!fwnode_property_read_bool(node, "read-only")) */  in idt_get_fw_data()
1123 		pdev->eero = false;  in idt_get_fw_data()
1127 		pdev->eesize, pdev->eeaddr);  in idt_get_fw_data()
1131  * idt_create_pdev() - create and init data structure of the driver
1132  * @client:	i2c client of IDT PCIe-switch device
1139 	pdev = devm_kmalloc(&client->dev, sizeof(struct idt_89hpesx_dev),  in idt_create_pdev()
1142 		return ERR_PTR(-ENOMEM);  in idt_create_pdev()
1145 	pdev->client = client;  in idt_create_pdev()
1151 	/* Initialize basic CSR CMD field - use full DWORD-sized r/w ops */  in idt_create_pdev()
1152 	pdev->inicsrcmd = CSR_DWE;  in idt_create_pdev()
1153 	pdev->csr = CSR_DEF;  in idt_create_pdev()
1156 	if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_PEC)) {  in idt_create_pdev()
1157 		pdev->iniccode = CCODE_PEC;  in idt_create_pdev()
1158 		client->flags |= I2C_CLIENT_PEC;  in idt_create_pdev()
1160 		pdev->iniccode = 0;  in idt_create_pdev()
1167  * idt_free_pdev() - free data structure of the driver
1173 	i2c_set_clientdata(pdev->client, NULL);  in idt_free_pdev()
1177  * idt_set_smbus_ops() - set supported SMBus operations
1183 	struct i2c_adapter *adapter = pdev->client->adapter;  in idt_set_smbus_ops()
1184 	struct device *dev = &pdev->client->dev;  in idt_set_smbus_ops()
1186 	/* Check i2c adapter read functionality */  in idt_set_smbus_ops()
1189 		pdev->smb_read = idt_smb_read_block;  in idt_set_smbus_ops()
1190 		dev_dbg(dev, "SMBus block-read op chosen");  in idt_set_smbus_ops()
1193 		pdev->smb_read = idt_smb_read_i2c_block;  in idt_set_smbus_ops()
1194 		dev_dbg(dev, "SMBus i2c-block-read op chosen");  in idt_set_smbus_ops()
1199 		pdev->smb_read = idt_smb_read_word;  in idt_set_smbus_ops()
1203 		pdev->smb_read = idt_smb_read_byte;  in idt_set_smbus_ops()
1207 		return -EPFNOSUPPORT;  in idt_set_smbus_ops()
1210 	/* Check i2c adapter write functionality */  in idt_set_smbus_ops()
1213 		pdev->smb_write = idt_smb_write_block;  in idt_set_smbus_ops()
1214 		dev_dbg(dev, "SMBus block-write op chosen");  in idt_set_smbus_ops()
1217 		pdev->smb_write = idt_smb_write_i2c_block;  in idt_set_smbus_ops()
1218 		dev_dbg(dev, "SMBus i2c-block-write op chosen");  in idt_set_smbus_ops()
1223 		pdev->smb_write = idt_smb_write_word;  in idt_set_smbus_ops()
1227 		pdev->smb_write = idt_smb_write_byte;  in idt_set_smbus_ops()
1231 		return -EPFNOSUPPORT;  in idt_set_smbus_ops()
1235 	mutex_init(&pdev->smb_mtx);  in idt_set_smbus_ops()
1241  * idt_check_dev() - check whether it's really IDT 89HPESx device
1243  * Return status of i2c adapter check operation
1247 	struct device *dev = &pdev->client->dev;  in idt_check_dev()
1261 		return -ENODEV;  in idt_check_dev()
1271  * idt_create_sysfs_files() - create sysfs attribute files
1277 	struct device *dev = &pdev->client->dev;  in idt_create_sysfs_files()
1281 	if (pdev->eesize == 0) {  in idt_create_sysfs_files()
1282 		dev_dbg(dev, "Skip creating sysfs-files");  in idt_create_sysfs_files()
1290 	pdev->ee_file = devm_kmemdup(dev, &bin_attr_eeprom,  in idt_create_sysfs_files()
1291 				     sizeof(*pdev->ee_file), GFP_KERNEL);  in idt_create_sysfs_files()
1292 	if (!pdev->ee_file)  in idt_create_sysfs_files()
1293 		return -ENOMEM;  in idt_create_sysfs_files()
1295 	/* In case of read-only EEPROM get rid of write ability */  in idt_create_sysfs_files()
1296 	if (pdev->eero) {  in idt_create_sysfs_files()
1297 		pdev->ee_file->attr.mode &= ~0200;  in idt_create_sysfs_files()
1298 		pdev->ee_file->write = NULL;  in idt_create_sysfs_files()
1301 	pdev->ee_file->size = pdev->eesize;  in idt_create_sysfs_files()
1302 	ret = sysfs_create_bin_file(&dev->kobj, pdev->ee_file);  in idt_create_sysfs_files()
1304 		dev_err(dev, "Failed to create EEPROM sysfs-node");  in idt_create_sysfs_files()
1312  * idt_remove_sysfs_files() - remove sysfs attribute files
1317 	struct device *dev = &pdev->client->dev;  in idt_remove_sysfs_files()
1320 	if (pdev->eesize == 0)  in idt_remove_sysfs_files()
1324 	sysfs_remove_bin_file(&dev->kobj, pdev->ee_file);  in idt_remove_sysfs_files()
1328  * idt_create_dbgfs_files() - create debugfs files
1334 	struct i2c_client *cli = pdev->client;  in idt_create_dbgfs_files()
1338 	snprintf(fname, CSRNAME_LEN, "%d-%04hx", cli->adapter->nr, cli->addr);  in idt_create_dbgfs_files()
1339 	pdev->csr_dir = debugfs_create_dir(fname, csr_dbgdir);  in idt_create_dbgfs_files()
1342 	debugfs_create_file(cli->name, 0600, pdev->csr_dir, pdev,  in idt_create_dbgfs_files()
1347  * idt_remove_dbgfs_files() - remove debugfs files
1352 	/* Remove CSR directory and it sysfs-node */  in idt_remove_dbgfs_files()
1353 	debugfs_remove_recursive(pdev->csr_dir);  in idt_remove_dbgfs_files()
1357  * idt_probe() - IDT 89HPESx driver probe() callback method
1396  * idt_remove() - IDT 89HPESx driver remove() callback method
1413  * ee_ids - array of supported EEPROMs
1423 MODULE_DEVICE_TABLE(i2c, ee_ids);
1426  * idt_ids - supported IDT 89HPESx devices
1460 	/* { "89hpes3t3" }, // No SMBus-slave iface */
1463 	/* { "89hpes4t4" }, // No SMBus-slave iface */
1483 MODULE_DEVICE_TABLE(i2c, idt_ids);
1542  * idt_driver - IDT 89HPESx driver structure
1555  * idt_init() - IDT 89HPESx driver init() callback method
1565 	/* Add new i2c-device driver */  in idt_init()
1577  * idt_exit() - IDT 89HPESx driver exit() callback method
1584 	/* Unregister i2c-device driver */  in idt_exit()