eeprom: Add IDT 89HPESx EEPROM/CSR driver

  This driver provides an access to EEPROM of IDT PCIe-switches. IDT PCIe-
switches expose a simple SMBus interface to perform IO-operations from/to
EEPROM, which is located at private (so called Master) SMBus. The driver
creates a simple binary sysfs-file to have an access to the EEPROM using
the SMBus-slave interface in the i2c-device susfs-directory:
     /sys/bus/i2c/devices/<bus>-<devaddr>/eeprom
In case if read-only flag is specified at dts-node of the device, User-space
applications won't be able to write to the EEPROM sysfs-node.

  Additionally IDT 89HPESx SMBus interface has an ability to read/write
values of device CSRs. This driver exposes debugfs-file to perform simple
IO-operations using that ability for just basic debug purpose. Particularly
the next file is created in the specific debugfs-directory:
     /sys/kernel/debug/idt_csr/
Format of the debugfs-file value is:
     $ cat /sys/kernel/debug/idt_csr/<bus>-<devaddr>/<devname>;
     <CSR address>:<CSR value>
So reading the content of the file gives current CSR address and it value.
If User-space application wishes to change current CSR address, it can just
write a proper value to the sysfs-file:
     $ echo "<CSR address>" >
         /sys/kernel/debug/idt_csr/<bus>-<devaddr>/<devname>
If it wants to change the CSR value as well, the format of the write
operation is:
     $ echo "<CSR address>:<CSR value>" > \
         /sys/kernel/debug/idt_csr/<bus>-<devaddr>/<devname>;
CSR address and value can be any of hexadecimal, decimal or octal format.

Signed-off-by: Serge Semin <fancer.lancer@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

3 files changed, 1598 insertions, 0 deletions

diff --git a/drivers/misc/eeprom/Kconfig b/drivers/misc/eeprom/Kconfig
index c4e41c26649e..de58762097c4 100644
--- a/drivers/misc/eeprom/Kconfig
+++ b/drivers/misc/eeprom/Kconfig
@@ -100,4 +100,14 @@ config EEPROM_DIGSY_MTC_CFG
 
 	  If unsure, say N.
 
+config EEPROM_IDT_89HPESX
+	tristate "IDT 89HPESx PCIe-swtiches EEPROM / CSR support"
+	depends on I2C && SYSFS
+	help
+	  Enable this driver to get read/write access to EEPROM / CSRs
+	  over IDT PCIe-swtich i2c-slave interface.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called idt_89hpesx.
+
 endmenu
diff --git a/drivers/misc/eeprom/Makefile b/drivers/misc/eeprom/Makefile
index fc1e81d29267..90a52624ddeb 100644
--- a/drivers/misc/eeprom/Makefile
+++ b/drivers/misc/eeprom/Makefile
@@ -5,3 +5,4 @@ obj-$(CONFIG_EEPROM_MAX6875)	+= max6875.o
 obj-$(CONFIG_EEPROM_93CX6)	+= eeprom_93cx6.o
 obj-$(CONFIG_EEPROM_93XX46)	+= eeprom_93xx46.o
 obj-$(CONFIG_EEPROM_DIGSY_MTC_CFG) += digsy_mtc_eeprom.o
+obj-$(CONFIG_EEPROM_IDT_89HPESX) += idt_89hpesx.o
diff --git a/drivers/misc/eeprom/idt_89hpesx.c b/drivers/misc/eeprom/idt_89hpesx.c
new file mode 100644
index 000000000000..25d47d09e1cb
--- /dev/null
+++ b/drivers/misc/eeprom/idt_89hpesx.c
@@ -0,0 +1,1587 @@
+/*
+ *   This file is provided under a GPLv2 license.  When using or
+ *   redistributing this file, you may do so under that license.
+ *
+ *   GPL LICENSE SUMMARY
+ *
+ *   Copyright (C) 2016 T-Platforms. All Rights Reserved.
+ *
+ *   This program is free software; you can redistribute it and/or modify it
+ *   under the terms and conditions of the GNU General Public License,
+ *   version 2, as published by the Free Software Foundation.
+ *
+ *   This program is distributed in the hope that it will be useful, but WITHOUT
+ *   ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ *   FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ *   more details.
+ *
+ *   You should have received a copy of the GNU General Public License along
+ *   with this program; if not, it can be found <http://www.gnu.org/licenses/>.
+ *
+ *   The full GNU General Public License is included in this distribution in
+ *   the file called "COPYING".
+ *
+ *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ *   A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ *   OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ *   SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ *   LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ *   DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ *   THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ *   (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * IDT PCIe-switch NTB Linux driver
+ *
+ * Contact Information:
+ * Serge Semin <fancer.lancer@gmail.com>, <Sergey.Semin@t-platforms.ru>
+ */
+/*
+ *           NOTE of the IDT 89HPESx SMBus-slave interface driver
+ *    This driver primarily is developed to have an access to EEPROM device of
+ * IDT PCIe-switches. IDT provides a simple SMBus interface to perform IO-
+ * operations from/to EEPROM, which is located at private (so called Master)
+ * SMBus of switches. Using that interface this the driver creates a simple
+ * binary sysfs-file in the device directory:
+ * /sys/bus/i2c/devices/<bus>-<devaddr>/eeprom
+ * In case if read-only flag is specified in the dts-node of device desription,
+ * User-space applications won't be able to write to the EEPROM sysfs-node.
+ *    Additionally IDT 89HPESx SMBus interface has an ability to write/read
+ * data of device CSRs. This driver exposes debugf-file to perform simple IO
+ * operations using that ability for just basic debug purpose. Particularly
+ * next file is created in the specific debugfs-directory:
+ * /sys/kernel/debug/idt_csr/
+ * Format of the debugfs-node is:
+ * $ cat /sys/kernel/debug/idt_csr/<bus>-<devaddr>/<devname>;
+ * <CSR address>:<CSR value>
+ * So reading the content of the file gives current CSR address and it value.
+ * If User-space application wishes to change current CSR address,
+ * it can just write a proper value to the sysfs-file:
+ * $ echo "<CSR address>" > /sys/kernel/debug/idt_csr/<bus>-<devaddr>/<devname>
+ * If it wants to change the CSR value as well, the format of the write
+ * operation is:
+ * $ echo "<CSR address>:<CSR value>" > \
+ *        /sys/kernel/debug/idt_csr/<bus>-<devaddr>/<devname>;
+ * CSR address and value can be any of hexadecimal, decimal or octal format.
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/sizes.h>
+#include <linux/slab.h>
+#include <linux/mutex.h>
+#include <linux/sysfs.h>
+#include <linux/debugfs.h>
+#include <linux/mod_devicetable.h>
+#include <linux/of.h>
+#include <linux/i2c.h>
+#include <linux/pci_ids.h>
+#include <linux/delay.h>
+
+#define IDT_NAME		"89hpesx"
+#define IDT_89HPESX_DESC	"IDT 89HPESx SMBus-slave interface driver"
+#define IDT_89HPESX_VER		"1.0"
+
+MODULE_DESCRIPTION(IDT_89HPESX_DESC);
+MODULE_VERSION(IDT_89HPESX_VER);
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("T-platforms");
+
+/*
+ * csr_dbgdir - CSR read/write operations Debugfs directory
+ */
+static struct dentry *csr_dbgdir;
+
+/*
+ * struct idt_89hpesx_dev - IDT 89HPESx device data structure
+ * @eesize:	Size of EEPROM in bytes (calculated from "idt,eecompatible")
+ * @eero:	EEPROM Read-only flag
+ * @eeaddr:	EEPROM custom address
+ *
+ * @inieecmd:	Initial cmd value for EEPROM read/write operations
+ * @inicsrcmd:	Initial cmd value for CSR read/write operations
+ * @iniccode:	Initialial command code value for IO-operations
+ *
+ * @csr:	CSR address to perform read operation
+ *
+ * @smb_write:	SMBus write method
+ * @smb_read:	SMBus read method
+ * @smb_mtx:	SMBus mutex
+ *
+ * @client:	i2c client used to perform IO operations
+ *
+ * @ee_file:	EEPROM read/write sysfs-file
+ * @csr_file:	CSR read/write debugfs-node
+ */
+struct idt_smb_seq;
+struct idt_89hpesx_dev {
+	u32 eesize;
+	bool eero;
+	u8 eeaddr;
+
+	u8 inieecmd;
+	u8 inicsrcmd;
+	u8 iniccode;
+
+	u16 csr;
+
+	int (*smb_write)(struct idt_89hpesx_dev *, const struct idt_smb_seq *);
+	int (*smb_read)(struct idt_89hpesx_dev *, struct idt_smb_seq *);
+	struct mutex smb_mtx;
+
+	struct i2c_client *client;
+
+	struct bin_attribute *ee_file;
+	struct dentry *csr_dir;
+	struct dentry *csr_file;
+};
+
+/*
+ * struct idt_smb_seq - sequence of data to be read/written from/to IDT 89HPESx
+ * @ccode:	SMBus command code
+ * @bytecnt:	Byte count of operation
+ * @data:	Data to by written
+ */
+struct idt_smb_seq {
+	u8 ccode;
+	u8 bytecnt;
+	u8 *data;
+};
+
+/*
+ * struct idt_eeprom_seq - sequence of data to be read/written from/to EEPROM
+ * @cmd:	Transaction CMD
+ * @eeaddr:	EEPROM custom address
+ * @memaddr:	Internal memory address of EEPROM
+ * @data:	Data to be written at the memory address
+ */
+struct idt_eeprom_seq {
+	u8 cmd;
+	u8 eeaddr;
+	u16 memaddr;
+	u8 data;
+} __packed;
+
+/*
+ * struct idt_csr_seq - sequence of data to be read/written from/to CSR
+ * @cmd:	Transaction CMD
+ * @csraddr:	Internal IDT device CSR address
+ * @data:	Data to be read/written from/to the CSR address
+ */
+struct idt_csr_seq {
+	u8 cmd;
+	u16 csraddr;
+	u32 data;
+} __packed;
+
+/*
+ * SMBus command code macros
+ * @CCODE_END:		Indicates the end of transaction
+ * @CCODE_START:	Indicates the start of transaction
+ * @CCODE_CSR:		CSR read/write transaction
+ * @CCODE_EEPROM:	EEPROM read/write transaction
+ * @CCODE_BYTE:		Supplied data has BYTE length
+ * @CCODE_WORD:		Supplied data has WORD length
+ * @CCODE_BLOCK:	Supplied data has variable length passed in bytecnt
+ *			byte right following CCODE byte
+ */
+#define CCODE_END	((u8)0x01)
+#define CCODE_START	((u8)0x02)
+#define CCODE_CSR	((u8)0x00)
+#define CCODE_EEPROM	((u8)0x04)
+#define CCODE_BYTE	((u8)0x00)
+#define CCODE_WORD	((u8)0x20)
+#define CCODE_BLOCK	((u8)0x40)
+#define CCODE_PEC	((u8)0x80)
+
+/*
+ * EEPROM command macros
+ * @EEPROM_OP_WRITE:	EEPROM write operation
+ * @EEPROM_OP_READ:	EEPROM read operation
+ * @EEPROM_USA:		Use specified address of EEPROM
+ * @EEPROM_NAERR:	EEPROM device is not ready to respond
+ * @EEPROM_LAERR:	EEPROM arbitration loss error
+ * @EEPROM_MSS:		EEPROM misplace start & stop bits error
+ * @EEPROM_WR_CNT:	Bytes count to perform write operation
+ * @EEPROM_WRRD_CNT:	Bytes count to write before reading
+ * @EEPROM_RD_CNT:	Bytes count to perform read operation
+ * @EEPROM_DEF_SIZE:	Fall back size of EEPROM
+ * @EEPROM_DEF_ADDR:	Defatul EEPROM address
+ * @EEPROM_TOUT:	Timeout before retry read operation if eeprom is busy
+ */
+#define EEPROM_OP_WRITE	((u8)0x00)
+#define EEPROM_OP_READ	((u8)0x01)
+#define EEPROM_USA	((u8)0x02)
+#define EEPROM_NAERR	((u8)0x08)
+#define EEPROM_LAERR    ((u8)0x10)
+#define EEPROM_MSS	((u8)0x20)
+#define EEPROM_WR_CNT	((u8)5)
+#define EEPROM_WRRD_CNT	((u8)4)
+#define EEPROM_RD_CNT	((u8)5)
+#define EEPROM_DEF_SIZE	((u16)4096)
+#define EEPROM_DEF_ADDR	((u8)0x50)
+#define EEPROM_TOUT	(100)
+
+/*
+ * CSR command macros
+ * @CSR_DWE:		Enable all four bytes of the operation
+ * @CSR_OP_WRITE:	CSR write operation
+ * @CSR_OP_READ:	CSR read operation
+ * @CSR_RERR:		Read operation error
+ * @CSR_WERR:		Write operation error
+ * @CSR_WR_CNT:		Bytes count to perform write operation
+ * @CSR_WRRD_CNT:	Bytes count to write before reading
+ * @CSR_RD_CNT:		Bytes count to perform read operation
+ * @CSR_MAX:		Maximum CSR address
+ * @CSR_DEF:		Default CSR address
+ * @CSR_REAL_ADDR:	CSR real unshifted address
+ */
+#define CSR_DWE			((u8)0x0F)
+#define CSR_OP_WRITE		((u8)0x00)
+#define CSR_OP_READ		((u8)0x10)
+#define CSR_RERR		((u8)0x40)
+#define CSR_WERR		((u8)0x80)
+#define CSR_WR_CNT		((u8)7)
+#define CSR_WRRD_CNT		((u8)3)
+#define CSR_RD_CNT		((u8)7)
+#define CSR_MAX			((u32)0x3FFFF)
+#define CSR_DEF			((u16)0x0000)
+#define CSR_REAL_ADDR(val)	((unsigned int)val << 2)
+
+/*
+ * IDT 89HPESx basic register
+ * @IDT_VIDDID_CSR:	PCIe VID and DID of IDT 89HPESx
+ * @IDT_VID_MASK:	Mask of VID
+ */
+#define IDT_VIDDID_CSR	((u32)0x0000)
+#define IDT_VID_MASK	((u32)0xFFFF)
+
+/*
+ * IDT 89HPESx can send NACK when new command is sent before previous one
+ * fininshed execution. In this case driver retries operation
+ * certain times.
+ * @RETRY_CNT:		Number of retries before giving up and fail
+ * @idt_smb_safe:	Generate a retry loop on corresponding SMBus method
+ */
+#define RETRY_CNT (128)
+#define idt_smb_safe(ops, args...) ({ \
+	int __retry = RETRY_CNT; \
+	s32 __sts; \
+	do { \
+		__sts = i2c_smbus_ ## ops ## _data(args); \
+	} while (__retry-- && __sts < 0); \
+	__sts; \
+})
+
+/*===========================================================================
+ *                         i2c bus level IO-operations
+ *===========================================================================
+ */
+
+/*
+ * idt_smb_write_byte() - SMBus write method when I2C_SMBUS_BYTE_DATA operation
+ *                        is only available
+ * @pdev:	Pointer to the driver data
+ * @seq:	Sequence of data to be written
+ */
+static int idt_smb_write_byte(struct idt_89hpesx_dev *pdev,
+			      const struct idt_smb_seq *seq)
+{
+	s32 sts;
+	u8 ccode;
+	int idx;
+
+	/* Loop over the supplied data sending byte one-by-one */
+	for (idx = 0; idx < seq->bytecnt; idx++) {
+		/* Collect the command code byte */
+		ccode = seq->ccode | CCODE_BYTE;
+		if (idx == 0)
+			ccode |= CCODE_START;
+		if (idx == seq->bytecnt - 1)
+			ccode |= CCODE_END;
+
+		/* Send data to the device */
+		sts = idt_smb_safe(write_byte, pdev->client, ccode,
+			seq->data[idx]);
+		if (sts != 0)
+			return (int)sts;
+	}
+
+	return 0;
+}
+
+/*
+ * idt_smb_read_byte() - SMBus read method when I2C_SMBUS_BYTE_DATA operation
+ *                        is only available
+ * @pdev:	Pointer to the driver data
+ * @seq:	Buffer to read data to
+ */
+static int idt_smb_read_byte(struct idt_89hpesx_dev *pdev,
+			     struct idt_smb_seq *seq)
+{
+	s32 sts;
+	u8 ccode;
+	int idx;
+
+	/* Loop over the supplied buffer receiving byte one-by-one */
+	for (idx = 0; idx < seq->bytecnt; idx++) {
+		/* Collect the command code byte */
+		ccode = seq->ccode | CCODE_BYTE;
+		if (idx == 0)
+			ccode |= CCODE_START;
+		if (idx == seq->bytecnt - 1)
+			ccode |= CCODE_END;
+
+		/* Read data from the device */
+		sts = idt_smb_safe(read_byte, pdev->client, ccode);
+		if (sts < 0)
+			return (int)sts;
+
+		seq->data[idx] = (u8)sts;
+	}
+
+	return 0;
+}
+
+/*
+ * idt_smb_write_word() - SMBus write method when I2C_SMBUS_BYTE_DATA and
+ *                        I2C_FUNC_SMBUS_WORD_DATA operations are available
+ * @pdev:	Pointer to the driver data
+ * @seq:	Sequence of data to be written
+ */
+static int idt_smb_write_word(struct idt_89hpesx_dev *pdev,
+			      const struct idt_smb_seq *seq)
+{
+	s32 sts;
+	u8 ccode;
+	int idx, evencnt;
+
+	/* Calculate the even count of data to send */
+	evencnt = seq->bytecnt - (seq->bytecnt % 2);
+
+	/* Loop over the supplied data sending two bytes at a time */
+	for (idx = 0; idx < evencnt; idx += 2) {
+		/* Collect the command code byte */
+		ccode = seq->ccode | CCODE_WORD;
+		if (idx == 0)
+			ccode |= CCODE_START;
+		if (idx == evencnt - 2)
+			ccode |= CCODE_END;
+
+		/* Send word data to the device */
+		sts = idt_smb_safe(write_word, pdev->client, ccode,
+			*(u16 *)&seq->data[idx]);
+		if (sts != 0)
+			return (int)sts;
+	}
+
+	/* If there is odd number of bytes then send just one last byte */
+	if (seq->bytecnt != evencnt) {
+		/* Collect the command code byte */
+		ccode = seq->ccode | CCODE_BYTE | CCODE_END;
+		if (idx == 0)
+			ccode |= CCODE_START;
+
+		/* Send byte data to the device */
+		sts = idt_smb_safe(write_byte, pdev->client, ccode,
+			seq->data[idx]);
+		if (sts != 0)
+			return (int)sts;
+	}
+
+	return 0;
+}
+
+/*
+ * idt_smb_read_word() - SMBus read method when I2C_SMBUS_BYTE_DATA and
+ *                       I2C_FUNC_SMBUS_WORD_DATA operations are available
+ * @pdev:	Pointer to the driver data
+ * @seq:	Buffer to read data to
+ */
+static int idt_smb_read_word(struct idt_89hpesx_dev *pdev,
+			     struct idt_smb_seq *seq)
+{
+	s32 sts;
+	u8 ccode;
+	int idx, evencnt;
+
+	/* Calculate the even count of data to send */
+	evencnt = seq->bytecnt - (seq->bytecnt % 2);
+
+	/* Loop over the supplied data reading two bytes at a time */
+	for (idx = 0; idx < evencnt; idx += 2) {
+		/* Collect the command code byte */
+		ccode = seq->ccode | CCODE_WORD;
+		if (idx == 0)
+			ccode |= CCODE_START;
+		if (idx == evencnt - 2)
+			ccode |= CCODE_END;
+
+		/* Read word data from the device */
+		sts = idt_smb_safe(read_word, pdev->client, ccode);
+		if (sts < 0)
+			return (int)sts;
+
+		*(u16 *)&seq->data[idx] = (u16)sts;
+	}
+
+	/* If there is odd number of bytes then receive just one last byte */
+	if (seq->bytecnt != evencnt) {
+		/* Collect the command code byte */
+		ccode = seq->ccode | CCODE_BYTE | CCODE_END;
+		if (idx == 0)
+			ccode |= CCODE_START;
+
+		/* Read last data byte from the device */
+		sts = idt_smb_safe(read_byte, pdev->client, ccode);
+		if (sts < 0)
+			return (int)sts;
+
+		seq->data[idx] = (u8)sts;
+	}
+
+	return 0;
+}
+
+/*
+ * idt_smb_write_block() - SMBus write method when I2C_SMBUS_BLOCK_DATA
+ *                         operation is available
+ * @pdev:	Pointer to the driver data
+ * @seq:	Sequence of data to be written
+ */
+static int idt_smb_write_block(struct idt_89hpesx_dev *pdev,
+			       const struct idt_smb_seq *seq)
+{
+	u8 ccode;
+
+	/* Return error if too much data passed to send */
+	if (seq->bytecnt > I2C_SMBUS_BLOCK_MAX)
+		return -EINVAL;
+
+	/* Collect the command code byte */
+	ccode = seq->ccode | CCODE_BLOCK | CCODE_START | CCODE_END;
+
+	/* Send block of data to the device */
+	return idt_smb_safe(write_block, pdev->client, ccode, seq->bytecnt,
+		seq->data);
+}
+
+/*
+ * idt_smb_read_block() - SMBus read method when I2C_SMBUS_BLOCK_DATA
+ *                        operation is available
+ * @pdev:	Pointer to the driver data
+ * @seq:	Buffer to read data to
+ */
+static int idt_smb_read_block(struct idt_89hpesx_dev *pdev,
+			      struct idt_smb_seq *seq)
+{
+	s32 sts;
+	u8 ccode;
+
+	/* Return error if too much data passed to send */
+	if (seq->bytecnt > I2C_SMBUS_BLOCK_MAX)
+		return -EINVAL;
+
+	/* Collect the command code byte */
+	ccode = seq->ccode | CCODE_BLOCK | CCODE_START | CCODE_END;
+
+	/* Read block of data from the device */
+	sts = idt_smb_safe(read_block, pdev->client, ccode, seq->data);
+	if (sts != seq->bytecnt)
+		return (sts < 0 ? sts : -ENODATA);
+
+	return 0;
+}
+
+/*
+ * idt_smb_write_i2c_block() - SMBus write method when I2C_SMBUS_I2C_BLOCK_DATA
+ *                             operation is available
+ * @pdev:	Pointer to the driver data
+ * @seq:	Sequence of data to be written
+ *
+ * NOTE It's usual SMBus write block operation, except the actual data length is
+ * sent as first byte of data
+ */
+static int idt_smb_write_i2c_block(struct idt_89hpesx_dev *pdev,
+				   const struct idt_smb_seq *seq)
+{
+	u8 ccode, buf[I2C_SMBUS_BLOCK_MAX + 1];
+
+	/* Return error if too much data passed to send */
+	if (seq->bytecnt > I2C_SMBUS_BLOCK_MAX)
+		return -EINVAL;
+
+	/* Collect the data to send. Length byte must be added prior the data */
+	buf[0] = seq->bytecnt;
+	memcpy(&buf[1], seq->data, seq->bytecnt);
+
+	/* Collect the command code byte */
+	ccode = seq->ccode | CCODE_BLOCK | CCODE_START | CCODE_END;
+
+	/* Send length and block of data to the device */
+	return idt_smb_safe(write_i2c_block, pdev->client, ccode,
+		seq->bytecnt + 1, buf);
+}
+
+/*
+ * idt_smb_read_i2c_block() - SMBus read method when I2C_SMBUS_I2C_BLOCK_DATA
+ *                            operation is available
+ * @pdev:	Pointer to the driver data
+ * @seq:	Buffer to read data to
+ *
+ * NOTE It's usual SMBus read block operation, except the actual data length is
+ * retrieved as first byte of data
+ */
+static int idt_smb_read_i2c_block(struct idt_89hpesx_dev *pdev,
+				  struct idt_smb_seq *seq)
+{
+	u8 ccode, buf[I2C_SMBUS_BLOCK_MAX + 1];
+	s32 sts;
+
+	/* Return error if too much data passed to send */
+	if (seq->bytecnt > I2C_SMBUS_BLOCK_MAX)
+		return -EINVAL;
+
+	/* Collect the command code byte */
+	ccode = seq->ccode | CCODE_BLOCK | CCODE_START | CCODE_END;
+
+	/* Read length and block of data from the device */
+	sts = idt_smb_safe(read_i2c_block, pdev->client, ccode,
+		seq->bytecnt + 1, buf);
+	if (sts != seq->bytecnt + 1)
+		return (sts < 0 ? sts : -ENODATA);
+	if (buf[0] != seq->bytecnt)
+		return -ENODATA;
+
+	/* Copy retrieved data to the output data buffer */
+	memcpy(seq->data, &buf[1], seq->bytecnt);
+
+	return 0;
+}
+
+/*===========================================================================
+ *                          EEPROM IO-operations
+ *===========================================================================
+ */
+
+/*
+ * idt_eeprom_read_byte() - read just one byte from EEPROM
+ * @pdev:	Pointer to the driver data
+ * @memaddr:	Start EEPROM memory address
+ * @data:	Data to be written to EEPROM
+ */
+static int idt_eeprom_read_byte(struct idt_89hpesx_dev *pdev, u16 memaddr,
+				u8 *data)
+{
+	struct device *dev = &pdev->client->dev;
+	struct idt_eeprom_seq eeseq;
+	struct idt_smb_seq smbseq;
+	int ret, retry;
+
+	/* Initialize SMBus sequence fields */
+	smbseq.ccode = pdev->iniccode | CCODE_EEPROM;
+	smbseq.data = (u8 *)&eeseq;
+
+	/*
+	 * Sometimes EEPROM may respond with NACK if it's busy with previous
+	 * operation, so we need to perform a few attempts of read cycle
+	 */
+	retry = RETRY_CNT;
+	do {
+		/* Send EEPROM memory address to read data from */
+		smbseq.bytecnt = EEPROM_WRRD_CNT;
+		eeseq.cmd = pdev->inieecmd | EEPROM_OP_READ;
+		eeseq.eeaddr = pdev->eeaddr;
+		eeseq.memaddr = cpu_to_le16(memaddr);
+		ret = pdev->smb_write(pdev, &smbseq);
+		if (ret != 0) {
+			dev_err(dev, "Failed to init eeprom addr 0x%02hhx",
+				memaddr);
+			break;
+		}
+
+		/* Perform read operation */
+		smbseq.bytecnt = EEPROM_RD_CNT;
+		ret = pdev->smb_read(pdev, &smbseq);
+		if (ret != 0) {
+			dev_err(dev, "Failed to read eeprom data 0x%02hhx",
+				memaddr);
+			break;
+		}
+
+		/* Restart read operation if the device is busy */
+		if (retry && (eeseq.cmd & EEPROM_NAERR)) {
+			dev_dbg(dev, "EEPROM busy, retry reading after %d ms",
+				EEPROM_TOUT);
+			msleep(EEPROM_TOUT);
+			continue;
+		}
+
+		/* Check whether IDT successfully read data from EEPROM */
+		if (eeseq.cmd & (EEPROM_NAERR | EEPROM_LAERR | EEPROM_MSS)) {
+			dev_err(dev,
+				"Communication with eeprom failed, cmd 0x%hhx",
+				eeseq.cmd);
+			ret = -EREMOTEIO;
+			break;
+		}
+
+		/* Save retrieved data and exit the loop */
+		*data = eeseq.data;
+		break;
+	} while (retry--);
+
+	/* Return the status of operation */
+	return ret;
+}
+
+/*
+ * idt_eeprom_write() - EEPROM write operation
+ * @pdev:	Pointer to the driver data
+ * @memaddr:	Start EEPROM memory address
+ * @len:	Length of data to be written
+ * @data:	Data to be written to EEPROM
+ */
+static int idt_eeprom_write(struct idt_89hpesx_dev *pdev, u16 memaddr, u16 len,
+			    const u8 *data)
+{
+	struct device *dev = &pdev->client->dev;
+	struct idt_eeprom_seq eeseq;
+	struct idt_smb_seq smbseq;
+	int ret;
+	u16 idx;
+
+	/* Initialize SMBus sequence fields */
+	smbseq.ccode = pdev->iniccode | CCODE_EEPROM;
+	smbseq.data = (u8 *)&eeseq;
+
+	/* Send data byte-by-byte, checking if it is successfully written */
+	for (idx = 0; idx < len; idx++, memaddr++) {
+		/* Lock IDT SMBus device */
+		mutex_lock(&pdev->smb_mtx);
+
+		/* Perform write operation */
+		smbseq.bytecnt = EEPROM_WR_CNT;
+		eeseq.cmd = pdev->inieecmd | EEPROM_OP_WRITE;
+		eeseq.eeaddr = pdev->eeaddr;
+		eeseq.memaddr = cpu_to_le16(memaddr);
+		eeseq.data = data[idx];
+		ret = pdev->smb_write(pdev, &smbseq);
+		if (ret != 0) {
+			dev_err(dev,
+				"Failed to write 0x%04hx:0x%02hhx to eeprom",
+				memaddr, data[idx]);
+			goto err_mutex_unlock;
+		}
+
+		/*
+		 * Check whether the data is successfully written by reading
+		 * from the same EEPROM memory address.
+		 */
+		eeseq.data = ~data[idx];
+		ret = idt_eeprom_read_byte(pdev, memaddr, &eeseq.data);
+		if (ret != 0)
+			goto err_mutex_unlock;
+
+		/* Check whether the read byte is the same as written one */
+		if (eeseq.data != data[idx]) {
+			dev_err(dev, "Values don't match 0x%02hhx != 0x%02hhx",
+				eeseq.data, data[idx]);
+			ret = -EREMOTEIO;
+			goto err_mutex_unlock;
+		}
+
+		/* Unlock IDT SMBus device */
+err_mutex_unlock:
+		mutex_unlock(&pdev->smb_mtx);
+		if (ret != 0)
+			return ret;
+	}
+
+	return 0;
+}
+
+/*
+ * idt_eeprom_read() - EEPROM read operation
+ * @pdev:	Pointer to the driver data
+ * @memaddr:	Start EEPROM memory address
+ * @len:	Length of data to read
+ * @buf:	Buffer to read data to
+ */
+static int idt_eeprom_read(struct idt_89hpesx_dev *pdev, u16 memaddr, u16 len,
+			   u8 *buf)
+{
+	int ret;
+	u16 idx;
+
+	/* Read data byte-by-byte, retrying if it wasn't successful */
+	for (idx = 0; idx < len; idx++, memaddr++) {
+		/* Lock IDT SMBus device */
+		mutex_lock(&pdev->smb_mtx);
+
+		/* Just read the byte to the buffer */
+		ret = idt_eeprom_read_byte(pdev, memaddr, &buf[idx]);
+
+		/* Unlock IDT SMBus device */
+		mutex_unlock(&pdev->smb_mtx);
+
+		/* Return error if read operation failed */
+		if (ret != 0)
+			return ret;
+	}
+
+	return 0;
+}
+
+/*===========================================================================
+ *                          CSR IO-operations
+ *===========================================================================
+ */
+
+/*
+ * idt_csr_write() - CSR write operation
+ * @pdev:	Pointer to the driver data
+ * @csraddr:	CSR address (with no two LS bits)
+ * @data:	Data to be written to CSR
+ */
+static int idt_csr_write(struct idt_89hpesx_dev *pdev, u16 csraddr,
+			 const u32 data)
+{
+	struct device *dev = &pdev->client->dev;
+	struct idt_csr_seq csrseq;
+	struct idt_smb_seq smbseq;
+	int ret;
+
+	/* Initialize SMBus sequence fields */
+	smbseq.ccode = pdev->iniccode | CCODE_CSR;
+	smbseq.data = (u8 *)&csrseq;
+
+	/* Lock IDT SMBus device */
+	mutex_lock(&pdev->smb_mtx);
+
+	/* Perform write operation */
+	smbseq.bytecnt = CSR_WR_CNT;
+	csrseq.cmd = pdev->inicsrcmd | CSR_OP_WRITE;
+	csrseq.csraddr = cpu_to_le16(csraddr);
+	csrseq.data = cpu_to_le32(data);
+	ret = pdev->smb_write(pdev, &smbseq);
+	if (ret != 0) {
+		dev_err(dev, "Failed to write 0x%04x: 0x%04x to csr",
+			CSR_REAL_ADDR(csraddr), data);
+		goto err_mutex_unlock;
+	}
+
+	/* Send CSR address to read data from */
+	smbseq.bytecnt = CSR_WRRD_CNT;
+	csrseq.cmd = pdev->inicsrcmd | CSR_OP_READ;
+	ret = pdev->smb_write(pdev, &smbseq);
+	if (ret != 0) {
+		dev_err(dev, "Failed to init csr address 0x%04x",
+			CSR_REAL_ADDR(csraddr));
+		goto err_mutex_unlock;
+	}
+
+	/* Perform read operation */
+	smbseq.bytecnt = CSR_RD_CNT;
+	ret = pdev->smb_read(pdev, &smbseq);
+	if (ret != 0) {
+		dev_err(dev, "Failed to read csr 0x%04x",
+			CSR_REAL_ADDR(csraddr));
+		goto err_mutex_unlock;
+	}
+
+	/* Check whether IDT successfully retrieved CSR data */
+	if (csrseq.cmd & (CSR_RERR | CSR_WERR)) {
+		dev_err(dev, "IDT failed to perform CSR r/w");
+		ret = -EREMOTEIO;
+		goto err_mutex_unlock;
+	}
+
+	/* Unlock IDT SMBus device */
+err_mutex_unlock:
+	mutex_unlock(&pdev->smb_mtx);
+
+	return ret;
+}
+
+/*
+ * idt_csr_read() - CSR read operation
+ * @pdev:	Pointer to the driver data
+ * @csraddr:	CSR address (with no two LS bits)
+ * @data:	Data to be written to CSR
+ */
+static int idt_csr_read(struct idt_89hpesx_dev *pdev, u16 csraddr, u32 *data)
+{
+	struct device *dev = &pdev->client->dev;
+	struct idt_csr_seq csrseq;
+	struct idt_smb_seq smbseq;
+	int ret;
+
+	/* Initialize SMBus sequence fields */
+	smbseq.ccode = pdev->iniccode | CCODE_CSR;
+	smbseq.data = (u8 *)&csrseq;
+
+	/* Lock IDT SMBus device */
+	mutex_lock(&pdev->smb_mtx);
+
+	/* Send CSR register address before reading it */
+	smbseq.bytecnt = CSR_WRRD_CNT;
+	csrseq.cmd = pdev->inicsrcmd | CSR_OP_READ;
+	csrseq.csraddr = cpu_to_le16(csraddr);
+	ret = pdev->smb_write(pdev, &smbseq);
+	if (ret != 0) {
+		dev_err(dev, "Failed to init csr address 0x%04x",
+			CSR_REAL_ADDR(csraddr));
+		goto err_mutex_unlock;
+	}
+
+	/* Perform read operation */
+	smbseq.bytecnt = CSR_RD_CNT;
+	ret = pdev->smb_read(pdev, &smbseq);
+	if (ret != 0) {
+		dev_err(dev, "Failed to read csr 0x%04hx",
+			CSR_REAL_ADDR(csraddr));
+		goto err_mutex_unlock;
+	}
+
+	/* Check whether IDT successfully retrieved CSR data */
+	if (csrseq.cmd & (CSR_RERR | CSR_WERR)) {
+		dev_err(dev, "IDT failed to perform CSR r/w");
+		ret = -EREMOTEIO;
+		goto err_mutex_unlock;
+	}
+
+	/* Save data retrieved from IDT */
+	*data = le32_to_cpu(csrseq.data);
+
+	/* Unlock IDT SMBus device */
+err_mutex_unlock:
+	mutex_unlock(&pdev->smb_mtx);
+
+	return ret;
+}
+
+/*===========================================================================
+ *                          Sysfs/debugfs-nodes IO-operations
+ *===========================================================================
+ */
+
+/*
+ * eeprom_write() - EEPROM sysfs-node write callback
+ * @filep:	Pointer to the file system node
+ * @kobj:	Pointer to the kernel object related to the sysfs-node
+ * @attr:	Attributes of the file
+ * @buf:	Buffer to write data to
+ * @off:	Offset at which data should be written to
+ * @count:	Number of bytes to write
+ */
+static ssize_t eeprom_write(struct file *filp, struct kobject *kobj,
+			    struct bin_attribute *attr,
+			    char *buf, loff_t off, size_t count)
+{
+	struct idt_89hpesx_dev *pdev;
+	int ret;
+
+	/* Retrieve driver data */
+	pdev = dev_get_drvdata(kobj_to_dev(kobj));
+
+	/* Perform EEPROM write operation */
+	ret = idt_eeprom_write(pdev, (u16)off, (u16)count, (u8 *)buf);
+	return (ret != 0 ? ret : count);
+}
+
+/*
+ * eeprom_read() - EEPROM sysfs-node read callback
+ * @filep:	Pointer to the file system node
+ * @kobj:	Pointer to the kernel object related to the sysfs-node
+ * @attr:	Attributes of the file
+ * @buf:	Buffer to write data to
+ * @off:	Offset at which data should be written to
+ * @count:	Number of bytes to write
+ */
+static ssize_t eeprom_read(struct file *filp, struct kobject *kobj,
+			   struct bin_attribute *attr,
+			   char *buf, loff_t off, size_t count)
+{
+	struct idt_89hpesx_dev *pdev;
+	int ret;
+
+	/* Retrieve driver data */
+	pdev = dev_get_drvdata(kobj_to_dev(kobj));
+
+	/* Perform EEPROM read operation */
+	ret = idt_eeprom_read(pdev, (u16)off, (u16)count, (u8 *)buf);
+	return (ret != 0 ? ret : count);
+}
+
+/*
+ * idt_dbgfs_csr_write() - CSR debugfs-node write callback
+ * @filep:	Pointer to the file system file descriptor
+ * @buf:	Buffer to read data from
+ * @count:	Size of the buffer
+ * @offp:	Offset within the file
+ *
+ * It accepts either "0x<reg addr>:0x<value>" for saving register address
+ * and writing value to specified DWORD register or "0x<reg addr>" for
+ * just saving register address in order to perform next read operation.
+ *
+ * WARNING No spaces are allowed. Incoming string must be strictly formated as:
+ * "<reg addr>:<value>". Register address must be aligned within 4 bytes
+ * (one DWORD).
+ */
+static ssize_t idt_dbgfs_csr_write(struct file *filep, const char __user *ubuf,
+				   size_t count, loff_t *offp)
+{
+	struct idt_89hpesx_dev *pdev = filep->private_data;
+	char *colon_ch, *csraddr_str, *csrval_str;
+	int ret, csraddr_len, csrval_len;
+	u32 csraddr, csrval;
+	char *buf;
+
+	/* Copy data from User-space */
+	buf = kmalloc(count + 1, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	ret = simple_write_to_buffer(buf, count, offp, ubuf, count);
+	if (ret < 0)
+		goto free_buf;
+	buf[count] = 0;
+
+	/* Find position of colon in the buffer */
+	colon_ch = strnchr(buf, count, ':');
+
+	/*
+	 * If there is colon passed then new CSR value should be parsed as
+	 * well, so allocate buffer for CSR address substring.
+	 * If no colon is found, then string must have just one number with
+	 * no new CSR value
+	 */
+	if (colon_ch != NULL) {
+		csraddr_len = colon_ch - buf;
+		csraddr_str =
+			kmalloc(sizeof(char)*(csraddr_len + 1), GFP_KERNEL);
+		if (csraddr_str == NULL)
+			return -ENOMEM;
+		/* Copy the register address to the substring buffer */
+		strncpy(csraddr_str, buf, csraddr_len);
+		csraddr_str[csraddr_len] = '\0';
+		/* Register value must follow the colon */
+		csrval_str = colon_ch + 1;
+		csrval_len = strnlen(csrval_str, count - csraddr_len);
+	} else /* if (str_colon == NULL) */ {
+		csraddr_str = (char *)buf; /* Just to shut warning up */
+		csraddr_len = strnlen(csraddr_str, count);
+		csrval_str = NULL;
+		csrval_len = 0;
+	}
+
+	/* Convert CSR address to u32 value */
+	ret = kstrtou32(csraddr_str, 0, &csraddr);
+	if (ret != 0)
+		goto free_csraddr_str;
+
+	/* Check whether passed register address is valid */
+	if (csraddr > CSR_MAX || !IS_ALIGNED(csraddr, SZ_4)) {
+		ret = -EINVAL;
+		goto free_csraddr_str;
+	}
+
+	/* Shift register address to the right so to have u16 address */
+	pdev->csr = (csraddr >> 2);
+
+	/* Parse new CSR value and send it to IDT, if colon has been found */
+	if (colon_ch != NULL) {
+		ret = kstrtou32(csrval_str, 0, &csrval);
+		if (ret != 0)
+			goto free_csraddr_str;
+
+		ret = idt_csr_write(pdev, pdev->csr, csrval);
+		if (ret != 0)
+			goto free_csraddr_str;
+	}
+
+	/* Free memory only if colon has been found */
+free_csraddr_str:
+	if (colon_ch != NULL)
+		kfree(csraddr_str);
+
+	/* Free buffer allocated for data retrieved from User-space */
+free_buf:
+	kfree(buf);
+
+	return (ret != 0 ? ret : count);
+}
+
+/*
+ * idt_dbgfs_csr_read() - CSR debugfs-node read callback
+ * @filep:	Pointer to the file system file descriptor
+ * @buf:	Buffer to write data to
+ * @count:	Size of the buffer
+ * @offp:	Offset within the file
+ *
+ * It just prints the pair "0x<reg addr>:0x<value>" to passed buffer.
+ */
+#define CSRBUF_SIZE	((size_t)32)
+static ssize_t idt_dbgfs_csr_read(struct file *filep, char __user *ubuf,
+				  size_t count, loff_t *offp)
+{
+	struct idt_89hpesx_dev *pdev = filep->private_data;
+	u32 csraddr, csrval;
+	char buf[CSRBUF_SIZE];
+	int ret, size;
+