Hello linux folks,

    This driver primarily is developed to give an access to EEPROM of IDT
PCIe-switches. Such switches provide a simple SMBus interface to perform
IO-operations from/to EEPROM, which is located at private (also called master)
SMBus of the switches. Using that interface this 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 device dts-node, user-space
applications won't be able to write to the EEPROM sysfs-node.

    Additionally IDT 89HPESx SMBus interface provides an ability to write/read
data of device CSRs. This driver exposes corresponding sysfs-file to perform
simple IO operations using that facility for just basic debug purpose.
Particularly next file is created in the device specific sysfs-directory:
/sys/bus/i2c/devices/<bus>-<devaddr>/csr
Format of the sysfs-node is:
$ cat /sys/bus/i2c/devices/<bus>-<devaddr>/csr;
<CSR address>:<CSR value>
So reading the content of the sysfs-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/bus/i2c/devices/<bus>-<devaddr>/csr
If it wants to change the CSR value as well, the format of the write
operation is:
$ echo "<CSR address>:<CSR value>" > \
        /sys/bus/i2c/devices/<bus>-<devaddr>/csr;
CSR address and value can be any of hexadecimal, decimal or octal format.

    The driver supports the most of the commonly available SMBus operations:
SMBus i2c block, SMBus block, smbus word and byte. The code has been tested
to be built for x32/x64 MIPS architecture and tested on the x32 MIPS machine.
The patch was applied on top of commit c6935931c1894ff857616ff8549b61236a19148f
of master branch of repository
git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git


Thanks,

=============================
Serge V. Semin
Leading Programmer
Embedded SW development group
T-platforms
=============================

Signed-off-by: Serge Semin <fancer.lan...@gmail.com>

---
 .../devicetree/bindings/misc/idt_89hpesx.txt       |   41 +
 drivers/misc/eeprom/Kconfig                        |   10 +
 drivers/misc/eeprom/Makefile                       |    1 +
 drivers/misc/eeprom/idt_89hpesx.c                  | 1483 ++++++++++++++++++++
 4 files changed, 1535 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/misc/idt_89hpesx.txt
 create mode 100644 drivers/misc/eeprom/idt_89hpesx.c

diff --git a/Documentation/devicetree/bindings/misc/idt_89hpesx.txt 
b/Documentation/devicetree/bindings/misc/idt_89hpesx.txt
new file mode 100644
index 0000000..469cc93
--- /dev/null
+++ b/Documentation/devicetree/bindings/misc/idt_89hpesx.txt
@@ -0,0 +1,41 @@
+EEPROM / CSR SMBus-slave interface of IDT 89HPESx devices
+
+Required properties:
+  - compatible : should be "<manufacturer>,<type>"
+                Basically there is only one manufacturer: idt, but some
+                compatible devices may be produced in future. Following devices
+                are supported: 89hpes8nt2, 89hpes12nt3, 89hpes24nt6ag2,
+                89hpes32nt8ag2, 89hpes32nt8bg2, 89hpes12nt12g2, 89hpes16nt16g2,
+                89hpes24nt24g2, 89hpes32nt24ag2, 89hpes32nt24bg2;
+                89hpes12n3, 89hpes12n3a, 89hpes24n3, 89hpes24n3a;
+                89hpes32h8, 89hpes32h8g2, 89hpes48h12, 89hpes48h12g2,
+                89hpes48h12ag2, 89hpes16h16, 89hpes22h16, 89hpes22h16g2,
+                89hpes34h16, 89hpes34h16g2, 89hpes64h16, 89hpes64h16g2,
+                89hpes64h16ag2;
+                89hpes12t3g2, 89hpes24t3g2, 89hpes16t4, 89hpes4t4g2,
+                89hpes10t4g2, 89hpes16t4g2, 89hpes16t4ag2, 89hpes5t5,
+                89hpes6t5, 89hpes8t5, 89hpes8t5a, 89hpes24t6, 89hpes6t6g2,
+                89hpes24t6g2, 89hpes16t7, 89hpes32t8, 89hpes32t8g2,
+                89hpes48t12, 89hpes48t12g2.
+                Current implementation of the driver doesn't have any device-
+                specific functionalities. But since each of them differs
+                by registers mapping, CSRs read/write restrictions can be
+                added in future.
+  - reg :       I2C address of the IDT 89HPES device.
+
+Optional properties:
+  - read-only :         Parameterless property disables writes to the EEPROM
+  - idt,eesize : Size of EEPROM device connected to IDT 89HPES i2c-master bus
+                (default value is 4096 bytes if option isn't specified)
+  - idt,eeaddr : Custom address of EEPROM device
+                (If not specified IDT 89HPESx device will try to communicate
+                 with EEPROM sited by default address - 0x50)
+
+Example:
+       idt_pcie_sw@60 {
+               compatible = "idt,89hpes12nt3";
+               reg = <0x60>;
+               read-only;
+               idt,eesize = <65536>;
+               idt,eeaddr = <0x50>;
+       };
diff --git a/drivers/misc/eeprom/Kconfig b/drivers/misc/eeprom/Kconfig
index c4e41c2..de58762 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 fc1e81d..90a5262 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 0000000..f95f4f0
--- /dev/null
+++ b/drivers/misc/eeprom/idt_89hpesx.c
@@ -0,0 +1,1483 @@
+/*
+ *   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.lan...@gmail.com>, <sergey.se...@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 another sysfs-file to perform
+ * simple IO operations using that ability for just basic debug purpose.
+ * Particularly next file is created in the device specific sysfs-directory:
+ * /sys/bus/i2c/devices/<bus>-<devaddr>/csr
+ * Format of the sysfs-node is:
+ * $ cat /sys/bus/i2c/devices/<bus>-<devaddr>/csr;
+ * <CSR address>:<CSR value>
+ * So reading the content of the sysfs-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/bus/i2c/devices/<bus>-<devaddr>/csr
+ * If it wants to change the CSR value as well, the format of the write
+ * operation is:
+ * $ echo "<CSR address>:<CSR value>" > \
+ *        /sys/bus/i2c/devices/<bus>-<devaddr>/csr;
+ * CSR address and value can be any of hexadecimal, decimal or octal format.
+ */
+
+/*
+ * Note: You can load this module with either option 'dyndbg=+p' or define the
+ * next preprocessor constant
+ */
+/* #define DEBUG */
+
+#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/mod_devicetable.h>
+#include <linux/of.h>
+#include <linux/i2c.h>
+#include <linux/pci_ids.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");
+
+/*
+ * Some common constant used in the driver for better readability:
+ * @SUCCESS:   Success of a function execution
+ */
+#define SUCCESS (0)
+
+/*
+ * 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
+ *
+ * @eenode:    EEPROM sysfs-node to read/write data to/from EEPROM
+ * @regnode:   Register sysfs-node to read/write CSRs
+ */
+struct idt_smb_seq;
+struct idt_89hpesx_dev {
+       u32 eesize;
+       bool eero;
+       u8 eeaddr;
+
+       u8 inieecmd;
+       u8 inicsrcmd;
+       u8 iniccode;
+
+       atomic_t 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 eenode;
+       struct bin_attribute regnode;
+};
+#define to_pdev_kobj(__kobj) \
+       dev_get_drvdata(container_of(__kobj, struct device, kobj))
+
+/*
+ * 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
+ */
+#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)
+
+/*
+ * 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 < SUCCESS); \
+       __sts; \
+})
+
+/*
+ * Wrapper dev_err/dev_warn/dev_info/dev_dbg macros
+ */
+#define dev_err_idt(pdev, args...) \
+       dev_err(&pdev->client->dev, ## args)
+#define dev_warn_idt(pdev, args...) \
+       dev_warn(&pdev->client->dev, ## args)
+#define dev_info_idt(pdev, args...) \
+       dev_info(&pdev->client->dev, ## args)
+#define dev_dbg_idt(pdev, args...) \
+       dev_dbg(&pdev->client->dev, ## args)
+
+/*===========================================================================
+ *                         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 != SUCCESS)
+                       return (int)sts;
+       }
+
+       return SUCCESS;
+}
+
+/*
+ * 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 < SUCCESS)
+                       return (int)sts;
+
+               seq->data[idx] = (u8)sts;
+       }
+
+       return SUCCESS;
+}
+
+/*
+ * 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 != SUCCESS)
+                       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 != SUCCESS)
+                       return (int)sts;
+       }
+
+       return SUCCESS;
+}
+
+/*
+ * 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 < SUCCESS)
+                       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 < SUCCESS)
+                       return (int)sts;
+
+               seq->data[idx] = (u8)sts;
+       }
+
+       return SUCCESS;
+}
+
+/*
+ * 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 < SUCCESS ? sts : -ENODATA);
+
+       return SUCCESS;
+}
+
+/*
+ * 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 < SUCCESS ? 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 SUCCESS;
+}
+
+/*===========================================================================
+ *                          EEPROM IO-operations
+ *===========================================================================
+ */
+
+/*
+ * 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 idt_eeprom_seq eeseq;
+       struct idt_smb_seq smbseq;
+       int ret, retry;
+       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 != SUCCESS) {
+                       dev_err_idt(pdev,
+                               "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. Sometimes EEPROM may
+                * respond with NACK if it's busy with writing previous data,
+                * 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;
+                       ret = pdev->smb_write(pdev, &smbseq);
+                       if (ret != SUCCESS) {
+                               dev_err_idt(pdev,
+                                       "Failed to init mem address 0x%02hhx",
+                                       memaddr);
+                               goto err_mutex_unlock;
+                       }
+
+                       /* Perform read operation */
+                       smbseq.bytecnt = EEPROM_RD_CNT;
+                       eeseq.data = ~data[idx];
+                       ret = pdev->smb_read(pdev, &smbseq);
+                       if (ret != SUCCESS) {
+                               dev_err_idt(pdev,
+                                       "Failed to read mem address 0x%02hhx",
+                                       memaddr);
+                               goto err_mutex_unlock;
+                       }
+               } while (retry-- && (eeseq.cmd & EEPROM_NAERR));
+
+               /* Check whether IDT successfully sent data to EEPROM */
+               if (eeseq.cmd & (EEPROM_NAERR | EEPROM_LAERR | EEPROM_MSS)) {
+                       dev_err_idt(pdev, "Communication with EEPROM failed");
+                       ret = -EREMOTEIO;
+                       goto err_mutex_unlock;
+               }
+               if (eeseq.data != data[idx]) {
+                       dev_err_idt(pdev,
+                               "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 != SUCCESS)
+                       return ret;
+       }
+
+       return SUCCESS;
+}
+
+/*
+ * 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)
+{
+       struct idt_eeprom_seq eeseq;
+       struct idt_smb_seq smbseq;
+       u16 idx;
+       int ret;
+
+       /* Initialize SMBus sequence fields */
+       smbseq.ccode = pdev->iniccode | CCODE_EEPROM;
+       smbseq.data = (u8 *)&eeseq;
+
+       /* Send data one-by-one, checking if it is successfully written */
+       for (idx = 0; idx < len; idx++, memaddr++) {
+               /* Lock IDT SMBus device */
+               mutex_lock(&pdev->smb_mtx);
+
+               /* 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 != SUCCESS) {
+                       dev_err_idt(pdev, "Failed to init mem address 0x%02hhx",
+                               memaddr);
+                       goto err_mutex_unlock;
+               }
+
+               /* Perform read operation (rest of fields stay the same) */
+               smbseq.bytecnt = EEPROM_RD_CNT;
+               ret = pdev->smb_read(pdev, &smbseq);
+               if (ret != SUCCESS) {
+                       dev_err_idt(pdev,
+                               "Failed to read eeprom address 0x%02hhx",
+                               memaddr);
+                       ret = -EREMOTEIO;
+                       goto err_mutex_unlock;
+               }
+
+               /* Check whether IDT successfully read data from EEPROM */
+               if (eeseq.cmd & (EEPROM_NAERR | EEPROM_LAERR | EEPROM_MSS)) {
+                       dev_err_idt(pdev, "Communication with eeprom failed");
+                       ret = -EREMOTEIO;
+                       goto err_mutex_unlock;
+               }
+
+               /* Save retrieved data */
+               buf[idx] = eeseq.data;
+
+               /* Unlock IDT SMBus device */
+err_mutex_unlock:
+               mutex_unlock(&pdev->smb_mtx);
+               if (ret != SUCCESS)
+                       return ret;
+       }
+
+       return SUCCESS;
+}
+
+/*===========================================================================
+ *                          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 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 != SUCCESS) {
+               dev_err_idt(pdev, "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 != SUCCESS) {
+               dev_err_idt(pdev, "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 != SUCCESS) {
+               dev_err_idt(pdev, "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_idt(pdev, "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 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 != SUCCESS) {
+               dev_err_idt(pdev, "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 != SUCCESS) {
+               dev_err_idt(pdev, "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_idt(pdev, "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-nodes IO-operations
+ *===========================================================================
+ */
+
+/*
+ * idt_sysfs_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 idt_sysfs_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 = to_pdev_kobj(kobj);
+
+       /* Perform EEPROM write operation */
+       ret = idt_eeprom_write(pdev, (u16)off, (u16)count, (u8 *)buf);
+       return (ret != SUCCESS ? ret : count);
+}
+
+/*
+ * idt_sysfs_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 idt_sysfs_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 = to_pdev_kobj(kobj);
+
+       /* Perform EEPROM read operation */
+       ret = idt_eeprom_read(pdev, (u16)off, (u16)count, (u8 *)buf);
+       return (ret != SUCCESS ? ret : count);
+}
+
+/*
+ * idt_sysfs_csr_store() - CSR sysfs-node write callback
+ * @kobj:      Pointer to the kernel object related to the sysfs-node
+ * @attr:      Attributes of the file
+ * @buf:       Buffer to write data to
+ * @count:     Size of the buffer
+ *
+ * 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_sysfs_csr_store(struct device *dev,
+                                  struct device_attribute *attr,
+                                  const char *buf, size_t count)
+{
+       struct idt_89hpesx_dev *pdev;
+       char *colon_ch, *csraddr_str, *csrval_str;
+       int ret, csraddr_len, csrval_len;
+       u32 csraddr, csrval;
+
+       /* Retrieve driver data */
+       pdev = dev_get_drvdata(dev);
+
+       /* 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 != SUCCESS)
+               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 */
+       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 != SUCCESS)
+                       goto free_csraddr_str;
+
+               ret = idt_csr_write(pdev, (u16)csraddr, csrval);
+               if (ret != SUCCESS)
+                       goto free_csraddr_str;
+       }
+
+       /* Save CSR address in the data structure for future read operations */
+       atomic_set(&pdev->csr, (int)csraddr);
+
+       /* Free memory only if colon has been found */
+free_csraddr_str:
+       if (colon_ch != NULL)
+               kfree(csraddr_str);
+
+       return (ret != SUCCESS ? ret : count);
+}
+
+/*
+ * idt_sysfs_csr_show() - CSR sysfs-node read callback
+ * @kobj:      Pointer to the kernel object related to the sysfs-node
+ * @attr:      Attributes of the file
+ * @buf:       Buffer to write data to
+ *
+ * It just prints the pair "0x<reg addr>:0x<value>" to passed buffer.
+ */
+static ssize_t idt_sysfs_csr_show(struct device *dev,
+                                 struct device_attribute *attr, char *buf)
+{
+       struct idt_89hpesx_dev *pdev;
+       u32 csraddr, csrval;
+       int ret;
+
+       /* Retrieve driver data */
+       pdev = dev_get_drvdata(dev);
+
+       /* Read current CSR address */
+       csraddr = atomic_read(&pdev->csr);
+
+       /* Perform CSR read operation */
+       ret = idt_csr_read(pdev, (u16)csraddr, &csrval);
+       if (ret != SUCCESS)
+               return ret;
+
+       /* Shift register address to the left so to have real address */
+       csraddr <<= 2;
+
+       /* Print the "0x<reg addr>:0x<value>" to buffer */
+       return snprintf(buf, PAGE_SIZE, "0x%05x:0x%08x\n",
+               (unsigned int)csraddr, (unsigned int)csrval);
+}
+
+/*
+ * eeprom_attribute - EEPROM sysfs-node attributes
+ *
+ * NOTE Size will be changed in compliance with OF node. EEPROM attribute will
+ * be read-only as well if the corresponding flag is specified in OF node.
+ */
+static struct bin_attribute eeprom_attribute = {
+       .attr = {
+               .name = "eeprom",
+               .mode = S_IRUGO | S_IWUSR
+       },
+       .size = EEPROM_DEF_SIZE,
+       .write = idt_sysfs_eeprom_write,
+       .read = idt_sysfs_eeprom_read
+};
+
+/*
+ * csr_attribute - CSR sysfs-node attributes
+ */
+static struct device_attribute csr_attribute = {
+       .attr = {
+               .name = "csr",
+               .mode = S_IRUGO | S_IWUSR
+       },
+       .store = idt_sysfs_csr_store,
+       .show = idt_sysfs_csr_show,
+};
+
+/*===========================================================================
+ *                       Driver init/deinit methods
+ *===========================================================================
+ */
+
+/*
+ * idt_set_defval() - set default device data parameters
+ * @pdev:      Pointer to the driver data
+ */
+static void idt_set_defval(struct idt_89hpesx_dev *pdev)
+{
+       /* If OF info is missing then use next values */
+       pdev->eesize = EEPROM_DEF_SIZE;
+       pdev->eero = true;
+       pdev->inieecmd = 0;
+       pdev->eeaddr = EEPROM_DEF_ADDR << 1;
+}
+
+#ifdef CONFIG_OF
+/*
+ * idt_get_ofdata() - get IDT i2c-device parameters from device tree
+ * @pdev:      Pointer to the driver data
+ */
+static void idt_get_ofdata(struct idt_89hpesx_dev *pdev)
+{
+       struct device_node *node = pdev->client->dev.of_node;
+       const __be32 *val;
+
+       /* Read dts node parameters */
+       if (node) {
+               /* Get EEPROM size from 'idt,eesize' */
+               val = of_get_property(node, "idt,eesize", NULL);
+               if (val != NULL) {
+                       pdev->eesize = be32_to_cpup(val);
+                       if (!is_power_of_2(pdev->eesize))
+                               dev_warn_idt(pdev,
+                                       "EEPROM size %u is not power of 2",
+                                       pdev->eesize);
+               } else /* if (val == NULL) */ {
+                       pdev->eesize = EEPROM_DEF_SIZE;
+                       dev_warn_idt(pdev,
+                               "No EEPROM size, set default %u bytes",
+                               pdev->eesize);
+               }
+
+               /* Get custom EEPROM address from 'idt,eeaddr' */
+               val = of_get_property(node, "idt,eeaddr", NULL);
+               if (val != NULL) {
+                       pdev->inieecmd = EEPROM_USA;
+                       pdev->eeaddr = be32_to_cpup(val) << 1;
+               } else /* if (val != NULL) */ {
+                       pdev->inieecmd = 0;
+                       pdev->eeaddr = EEPROM_DEF_ADDR << 1;
+               }
+
+               /* Check EEPROM 'read-only' flag */
+               if (of_get_property(node, "read-only", NULL))
+                       pdev->eero = true;
+               else /* if (!of_get_property(node, "read-only", NULL)) */
+                       pdev->eero = false;
+       } else {
+               dev_warn_idt(pdev, "No dts node, set default values");
+               idt_set_defval(pdev);
+       }
+}
+#else
+static void idt_get_ofdata(struct idt_89hpesx_dev *pdev)
+{
+       dev_warn_idt(pdev, "OF table is unsupported, set default values");
+
+       /* Nothing we can do, just set the default values */
+       idt_set_defval(pdev);
+}
+#endif /* CONFIG_OF */
+
+/*
+ * idt_create_pdev() - create and init data structure of the driver
+ * @client:    i2c client of IDT PCIe-switch device
+ */
+static struct idt_89hpesx_dev *idt_create_pdev(struct i2c_client *client)
+{
+       struct idt_89hpesx_dev *pdev;
+
+       /* Allocate memory for driver data */
+       pdev = devm_kmalloc(&client->dev, sizeof(struct idt_89hpesx_dev),
+               GFP_KERNEL);
+       if (pdev == NULL)
+               return ERR_PTR(-ENOMEM);
+
+       /* Initialize basic fields of the data */
+       pdev->client = client;
+       i2c_set_clientdata(client, pdev);
+
+       /* Read OF nodes information */
+       idt_get_ofdata(pdev);
+
+       /* Initialize basic CSR CMD field - use full DWORD-sized r/w ops */
+       pdev->inicsrcmd = CSR_DWE;
+       atomic_set(&pdev->csr, CSR_DEF);
+
+       /* Enable Packet Error Checking if it's supported by adapter */
+       if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_PEC)) {
+               pdev->iniccode = CCODE_PEC;
+               client->flags |= I2C_CLIENT_PEC;
+       } else /* PEC is unsupported */ {
+               pdev->iniccode = 0;
+       }
+
+       dev_dbg_idt(pdev, "IDT 89HPESx data created");
+
+       return pdev;
+}
+
+/*
+ * idt_free_pdev() - free data structure of the driver
+ * @pdev:      Pointer to the driver data
+ */
+static void idt_free_pdev(struct idt_89hpesx_dev *pdev)
+{
+       /* Clear driver data from device private field */
+       i2c_set_clientdata(pdev->client, NULL);
+
+       /* Just free memory allocated for data */
+       devm_kfree(&pdev->client->dev, pdev);
+
+       dev_dbg_idt(pdev, "IDT 89HPESx data discarded");
+}
+
+/*
+ * idt_set_smbus_ops() - set supported SMBus operations
+ * @pdev:      Pointer to the driver data
+ * Return status of smbus check operations
+ */
+static int idt_set_smbus_ops(struct idt_89hpesx_dev *pdev)
+{
+       struct i2c_adapter *adapter = pdev->client->adapter;
+
+       /* Check i2c adapter read functionality */
+       if (i2c_check_functionality(adapter,
+                                   I2C_FUNC_SMBUS_READ_BLOCK_DATA)) {
+               pdev->smb_read = idt_smb_read_block;
+               dev_dbg_idt(pdev, "SMBus block-read op chosen");
+       } else if (i2c_check_functionality(adapter,
+                                          I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
+               pdev->smb_read = idt_smb_read_i2c_block;
+               dev_dbg_idt(pdev, "SMBus i2c-block-read op chosen");
+       } else if (i2c_check_functionality(adapter,
+                                          I2C_FUNC_SMBUS_READ_WORD_DATA) &&
+                  i2c_check_functionality(adapter,
+                                          I2C_FUNC_SMBUS_READ_BYTE_DATA)) {
+               pdev->smb_read = idt_smb_read_word;
+               dev_warn_idt(pdev, "Use slow word/byte SMBus read ops");
+       } else if (i2c_check_functionality(adapter,
+                                          I2C_FUNC_SMBUS_READ_BYTE_DATA)) {
+               pdev->smb_read = idt_smb_read_byte;
+               dev_warn_idt(pdev, "Use slow byte SMBus read op");
+       } else /* no supported smbus read operations */ {
+               dev_err_idt(pdev, "No supported SMBus read op");
+               return -EPFNOSUPPORT;
+       }
+
+       /* Check i2c adapter write functionality */
+       if (i2c_check_functionality(adapter,
+                                   I2C_FUNC_SMBUS_WRITE_BLOCK_DATA)) {
+               pdev->smb_write = idt_smb_write_block;
+               dev_dbg_idt(pdev, "SMBus block-write op chosen");
+       } else if (i2c_check_functionality(adapter,
+                                          I2C_FUNC_SMBUS_WRITE_I2C_BLOCK)) {
+               pdev->smb_write = idt_smb_write_i2c_block;
+               dev_dbg_idt(pdev, "SMBus i2c-block-write op chosen");
+       } else if (i2c_check_functionality(adapter,
+                                          I2C_FUNC_SMBUS_WRITE_WORD_DATA) &&
+                  i2c_check_functionality(adapter,
+                                          I2C_FUNC_SMBUS_WRITE_BYTE_DATA)) {
+               pdev->smb_write = idt_smb_write_word;
+               dev_warn_idt(pdev, "Use slow word/byte SMBus write op");
+       } else if (i2c_check_functionality(adapter,
+                                          I2C_FUNC_SMBUS_WRITE_BYTE_DATA)) {
+               pdev->smb_write = idt_smb_write_byte;
+               dev_warn_idt(pdev, "Use slow byte SMBus write op");
+       } else /* no supported smbus write operations */ {
+               dev_err_idt(pdev, "No supported SMBus write op");
+               return -EPFNOSUPPORT;
+       }
+
+       /* Initialize IDT SMBus slave interface mutex */
+       mutex_init(&pdev->smb_mtx);
+
+       dev_dbg_idt(pdev, "SMBus functionality successfully checked");
+
+       return SUCCESS;
+}
+
+/*
+ * idt_check_dev() - check whether it's really IDT 89HPESx device
+ * @pdev:      Pointer to the driver data
+ * Return status of i2c adapter check operation
+ */
+static int idt_check_dev(struct idt_89hpesx_dev *pdev)
+{
+       u32 viddid;
+       int ret;
+
+       /* Read VID and DID directly from IDT memory space */
+       ret = idt_csr_read(pdev, IDT_VIDDID_CSR, &viddid);
+       if (ret != SUCCESS) {
+               dev_err_idt(pdev, "Failed to read VID/DID");
+               return ret;
+       }
+
+       /* Check whether it's IDT device */
+       if ((viddid & IDT_VID_MASK) != PCI_VENDOR_ID_IDT) {
+               dev_err_idt(pdev, "Got unsupported VID/DID: 0x%08x", viddid);
+               return -ENODEV;
+       }
+
+       dev_info_idt(pdev, "Found IDT 89HPES device VID:0x%04x, DID:0x%04x",
+               (viddid & IDT_VID_MASK), (viddid >> 16));
+
+       return SUCCESS;
+}
+
+/*
+ * idt_create_sysfs_files() - create sysfs attribute files
+ * @pdev:      Pointer to the driver data
+ * Return status of operation
+ */
+static int idt_create_sysfs_files(struct idt_89hpesx_dev *pdev)
+{
+       struct device *dev = &pdev->client->dev;
+       int ret;
+
+       /* In case of read-only EEPROM get rid of write ability */
+       if (pdev->eero) {
+               eeprom_attribute.attr.mode &= ~S_IWUSR;
+               eeprom_attribute.write = NULL;
+       }
+       /* Create EEPROM sysfs file */
+       eeprom_attribute.size = pdev->eesize;
+       ret = sysfs_create_bin_file(&dev->kobj, &eeprom_attribute);
+       if (ret != SUCCESS) {
+               dev_err_idt(pdev, "Failed to create EEPROM sysfs-node");
+               return ret;
+       }
+
+       /* Create CSR sysfs file */
+       ret = sysfs_create_file(&dev->kobj, &csr_attribute.attr);
+       if (ret != SUCCESS) {
+               dev_err_idt(pdev, "Failed to create CSR sysfs-node");
+               sysfs_remove_bin_file(&dev->kobj, &eeprom_attribute);
+               return ret;
+       }
+
+       dev_dbg_idt(pdev, "Sysfs-files created");
+
+       return SUCCESS;
+}
+
+/*
+ * idt_remove_sysfs_files() - remove sysfs attribute files
+ * @pdev:      Pointer to the driver data
+ */
+static void idt_remove_sysfs_files(struct idt_89hpesx_dev *pdev)
+{
+       struct device *dev = &pdev->client->dev;
+
+       /* Remove CSR sysfs file */
+       sysfs_remove_file(&dev->kobj, &csr_attribute.attr);
+
+       /* Remove EEPROM sysfs file */
+       sysfs_remove_bin_file(&dev->kobj, &eeprom_attribute);
+
+       dev_dbg_idt(pdev, "Sysfs-files removed");
+}
+
+/*
+ * idt_probe() - IDT 89HPESx driver probe() callback method
+ */
+static int idt_probe(struct i2c_client *client, const struct i2c_device_id *id)
+{
+       struct idt_89hpesx_dev *pdev;
+       int ret;
+
+       /* Create driver data */
+       pdev = idt_create_pdev(client);
+       if (IS_ERR(pdev))
+               return PTR_ERR(pdev);
+
+       /* Set SMBus operations */
+       ret = idt_set_smbus_ops(pdev);
+       if (ret != SUCCESS)
+               goto err_free_pdev;
+
+       /* Check whether it is truly IDT 89HPESx device */
+       ret = idt_check_dev(pdev);
+       if (ret != SUCCESS)
+               goto err_free_pdev;
+
+       /* Create sysfs files */
+       ret = idt_create_sysfs_files(pdev);
+       if (ret != SUCCESS)
+               goto err_free_pdev;
+
+       dev_dbg_idt(pdev, "IDT %s device probed", id->name);
+
+       return SUCCESS;
+
+err_free_pdev:
+       idt_free_pdev(pdev);
+
+       return ret;
+}
+
+/*
+ * idt_remove() - IDT 89HPESx driver remove() callback method
+ */
+static int idt_remove(struct i2c_client *client)
+{
+       struct idt_89hpesx_dev *pdev = i2c_get_clientdata(client);
+
+       /* Remove sysfs files first */
+       idt_remove_sysfs_files(pdev);
+
+       /* Discard driver data structure */
+       idt_free_pdev(pdev);
+
+       dev_dbg_idt(pdev, "IDT 89HPESx device removed");
+
+       return SUCCESS;
+}
+
+/*
+ * idt_ids - supported IDT 89HPESx devices
+ */
+static const struct i2c_device_id idt_ids[] = {
+       { "89hpes8nt2", 0 },
+       { "89hpes12nt3", 0 },
+
+       { "89hpes24nt6ag2", 0 },
+       { "89hpes32nt8ag2", 0 },
+       { "89hpes32nt8bg2", 0 },
+       { "89hpes12nt12g2", 0 },
+       { "89hpes16nt16g2", 0 },
+       { "89hpes24nt24g2", 0 },
+       { "89hpes32nt24ag2", 0 },
+       { "89hpes32nt24bg2", 0 },
+
+       { "89hpes12n3", 0 },
+       { "89hpes12n3a", 0 },
+       { "89hpes24n3", 0 },
+       { "89hpes24n3a", 0 },
+
+       { "89hpes32h8", 0 },
+       { "89hpes32h8g2", 0 },
+       { "89hpes48h12", 0 },
+       { "89hpes48h12g2", 0 },
+       { "89hpes48h12ag2", 0 },
+       { "89hpes16h16", 0 },
+       { "89hpes22h16", 0 },
+       { "89hpes22h16g2", 0 },
+       { "89hpes34h16", 0 },
+       { "89hpes34h16g2", 0 },
+       { "89hpes64h16", 0 },
+       { "89hpes64h16g2", 0 },
+       { "89hpes64h16ag2", 0 },
+
+       /* { "89hpes3t3", 0 }, // No SMBus-slave iface */
+       { "89hpes12t3g2", 0 },
+       { "89hpes24t3g2", 0 },
+       /* { "89hpes4t4", 0 }, // No SMBus-slave iface */
+       { "89hpes16t4", 0 },
+       { "89hpes4t4g2", 0 },
+       { "89hpes10t4g2", 0 },
+       { "89hpes16t4g2", 0 },
+       { "89hpes16t4ag2", 0 },
+       { "89hpes5t5", 0 },
+       { "89hpes6t5", 0 },
+       { "89hpes8t5", 0 },
+       { "89hpes8t5a", 0 },
+       { "89hpes24t6", 0 },
+       { "89hpes6t6g2", 0 },
+       { "89hpes24t6g2", 0 },
+       { "89hpes16t7", 0 },
+       { "89hpes32t8", 0 },
+       { "89hpes32t8g2", 0 },
+       { "89hpes48t12", 0 },
+       { "89hpes48t12g2", 0 },
+       { /* END OF LIST */ }
+};
+MODULE_DEVICE_TABLE(i2c, idt_ids);
+
+/*
+ * idt_driver - IDT 89HPESx driver structure
+ */
+static struct i2c_driver idt_driver = {
+       .driver = {
+               .name = IDT_NAME,
+               .owner = THIS_MODULE,
+       },
+       .probe = idt_probe,
+       .remove = idt_remove,
+       .id_table = idt_ids,
+};
+module_i2c_driver(idt_driver);
+
-- 
2.6.6

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