--- /dev/null
+Index: linux-3.14.30/drivers/i2c/busses/Kconfig
+===================================================================
+--- linux-3.14.30.orig/drivers/i2c/busses/Kconfig 2015-03-11 16:46:46.963996212 +0800
++++ linux-3.14.30/drivers/i2c/busses/Kconfig 2015-03-12 10:40:34.849574512 +0800
+@@ -663,6 +663,10 @@
+ tristate "Ralink I2C Controller"
+ select OF_I2C
+
++config I2C_MT7621
++ tristate "Mt7621 I2C Controller"
++ select OF_I2C
++
+ config HAVE_S3C2410_I2C
+ bool
+ help
+Index: linux-3.14.30/drivers/i2c/busses/Makefile
+===================================================================
+--- linux-3.14.30.orig/drivers/i2c/busses/Makefile 2015-03-11 16:46:46.967996212 +0800
++++ linux-3.14.30/drivers/i2c/busses/Makefile 2015-03-11 17:52:43.008121712 +0800
+@@ -64,6 +64,7 @@
+ obj-$(CONFIG_I2C_PXA) += i2c-pxa.o
+ obj-$(CONFIG_I2C_PXA_PCI) += i2c-pxa-pci.o
+ obj-$(CONFIG_I2C_RALINK) += i2c-ralink.o
++obj-$(CONFIG_I2C_MT7621) += i2c-mt7621.o
+ obj-$(CONFIG_I2C_RIIC) += i2c-riic.o
+ obj-$(CONFIG_I2C_S3C2410) += i2c-s3c2410.o
+ obj-$(CONFIG_I2C_S6000) += i2c-s6000.o
+Index: linux-3.14.30/drivers/i2c/busses/i2c-mt7621.c
+===================================================================
+--- /dev/null 1970-01-01 00:00:00.000000000 +0000
++++ linux-3.14.30/drivers/i2c/busses/i2c-mt7621.c 2015-03-12 11:45:00.449759139 +0800
+@@ -0,0 +1,358 @@
++/*
++ * drivers/i2c/busses/i2c-mt7621.c
++ *
++ * Copyright (C) 2013 Steven Liu <steven_liu@mediatek.com>
++ *
++ * Improve driver for i2cdetect from i2c-tools to detect i2c devices on the bus.
++ * (C) 2014 Sittisak <sittisaks@hotmail.com>
++ *
++ * This software is licensed under the terms of the GNU General Public
++ * License version 2, as published by the Free Software Foundation, and
++ * may be copied, distributed, and modified under those terms.
++ *
++ * 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.
++ *
++ */
++
++#include <linux/interrupt.h>
++#include <linux/kernel.h>
++#include <linux/module.h>
++#include <linux/reset.h>
++#include <linux/delay.h>
++#include <linux/slab.h>
++#include <linux/init.h>
++#include <linux/errno.h>
++#include <linux/platform_device.h>
++#include <linux/i2c.h>
++#include <linux/io.h>
++#include <linux/err.h>
++
++#include <asm/mach-ralink/ralink_regs.h>
++
++#define REG_CONFIG_REG 0x00
++#define REG_CLKDIV_REG 0x04
++#define REG_DEVADDR_REG 0x08
++#define REG_ADDR_REG 0x0C
++#define REG_DATAOUT_REG 0x10
++#define REG_DATAIN_REG 0x14
++#define REG_STATUS_REG 0x18
++#define REG_STARTXFR_REG 0x1C
++#define REG_BYTECNT_REG 0x20
++#define REG_SM0_IS_AUTOMODE 0x28
++#define REG_SM0CTL0 0x40
++
++
++#define I2C_STARTERR 0x10
++#define I2C_ACKERR 0x08
++#define I2C_DATARDY 0x04
++#define I2C_SDOEMPTY 0x02
++#define I2C_BUSY 0x01
++
++/* I2C_CFG register bit field */
++#define I2C_CFG_ADDRLEN_8 (7<<5) /* 8 bits */
++#define I2C_CFG_DEVADLEN_7 (6<<2)
++#define I2C_CFG_ADDRDIS (1<<1)
++#define I2C_CFG_DEVADDIS (1<<0)
++
++#define I2C_CFG_DEFAULT (I2C_CFG_ADDRLEN_8 | \
++ I2C_CFG_DEVADLEN_7 | \
++ I2C_CFG_ADDRDIS)
++
++#define I2C_RETRY 0x1000
++
++#define CLKDIV_VALUE 333
++#define i2c_busy_loop (CLKDIV_VALUE*30)
++
++#define READ_CMD 0x01
++#define WRITE_CMD 0x00
++#define READ_BLOCK 16
++
++#define I2C_OFFSET 0x900
++#define RSTCTRL_OFFSET 0x34
++
++#define MT7621_REG(x) (*((volatile u32 *)(x)))
++
++struct i2c_algo_mt7621_data{
++ u32 ioaddr;
++ wait_queue_head_t waitq;
++ spinlock_t lock;
++ int id;
++};
++/***********************************************************/
++
++static unsigned long clkdiv_value = CLKDIV_VALUE;
++
++static void __iomem *memsysctlbase;
++static void __iomem *membase;
++static struct i2c_adapter *adapter;
++static int i2c_id;
++
++static void rt_i2c_w32(u32 val, unsigned reg)
++{
++ iowrite32(val, membase + reg);
++}
++
++static u32 rt_i2c_r32(unsigned reg)
++{
++ return ioread32(membase + reg);
++}
++
++static void mt7621_i2c_reset(void)
++{
++ u32 val;
++ val = MT7621_REG(RSTCTRL_OFFSET+memsysctlbase);
++ val = val | (1<<16);
++ MT7621_REG(RSTCTRL_OFFSET+memsysctlbase) = val;
++ val = val & ~(1<<16);
++ MT7621_REG(RSTCTRL_OFFSET+memsysctlbase) = val;
++ udelay(500);
++}
++static void mt7621_i2c_enable(struct i2c_msg *msg)
++{
++ rt_i2c_w32(msg->addr,REG_DEVADDR_REG);
++ rt_i2c_w32(0,REG_ADDR_REG);
++}
++
++static void i2c_master_init(void)
++{
++ u32 value;
++ /*set mt7621 i2c mode*/
++ (*((volatile u32*)(memsysctlbase+0x60))) &=~0x4;
++
++ mt7621_i2c_reset();
++ rt_i2c_w32(I2C_CFG_DEFAULT,REG_CONFIG_REG);
++
++ value = 1<< 31;
++ value |= 1<<28;
++ value |= clkdiv_value <<16;
++ value |= 1<<6;
++ value |= 1<<1;
++ rt_i2c_w32(value,REG_SM0CTL0);
++ rt_i2c_w32(1,REG_SM0_IS_AUTOMODE);//auto mode
++}
++
++
++static inline int rt_i2c_wait_rx_done(void)
++{
++ int i=0;
++ while((!(rt_i2c_r32(REG_STATUS_REG) & I2C_DATARDY)) && (i<i2c_busy_loop))
++ i++;
++ if(i>=i2c_busy_loop){
++ pr_err("err,wait for idle timeout");
++ return -ETIMEDOUT;
++ }
++ return 0;
++}
++
++static inline int rt_i2c_wait_idle(void)
++{
++ int i=0;
++ while((rt_i2c_r32(REG_STATUS_REG) & I2C_BUSY) && (i<i2c_busy_loop))
++ i++;
++ if(i>=i2c_busy_loop){
++ pr_err("err,wait for idle timeout");
++ return -ETIMEDOUT;
++ }
++ return 0;
++}
++
++static inline int rt_i2c_wait_tx_done(void)
++{
++ int i=0;
++ while((!(rt_i2c_r32(REG_STATUS_REG) & I2C_SDOEMPTY)) && (i<i2c_busy_loop))
++ i++;
++ if(i>=i2c_busy_loop){
++ pr_err("err,wait for idle timeout");
++ return -ETIMEDOUT;
++ }
++ return 0;
++}
++
++static int rt_i2c_handle_msg(struct i2c_adapter *a, struct i2c_msg* msg)
++{
++ int i = 0, j = 0, pos = 0;
++ int nblock = msg->len / READ_BLOCK;
++ int rem = msg->len % READ_BLOCK;
++
++ if (msg->flags & I2C_M_TEN) {
++ printk("10 bits addr not supported\n");
++ return -EINVAL;
++ }
++
++ if (msg->flags & I2C_M_RD) {
++ for (i = 0; i < nblock; i++) {
++ if (rt_i2c_wait_idle())
++ goto ERR_TIMEOUT;
++ rt_i2c_w32(READ_BLOCK - 1, REG_BYTECNT_REG);
++ rt_i2c_w32(READ_CMD, REG_STARTXFR_REG);
++ for (j = 0; j < READ_BLOCK; j++) {
++ if (rt_i2c_wait_rx_done())
++ goto ERR_TIMEOUT;
++ msg->buf[pos++] = rt_i2c_r32(REG_DATAIN_REG);
++ }
++ }
++
++ if (rt_i2c_wait_idle()) {
++ goto ERR_TIMEOUT;
++ }
++
++ rt_i2c_w32(rem - 1, REG_BYTECNT_REG);
++ rt_i2c_w32(READ_CMD, REG_STARTXFR_REG);
++
++ for (i = 0; i < rem; i++) {
++ if (rt_i2c_wait_rx_done())
++ goto ERR_TIMEOUT;
++ msg->buf[pos++] = rt_i2c_r32(REG_DATAIN_REG);
++ }
++ } else {
++ if (rt_i2c_wait_idle()) {
++ goto ERR_TIMEOUT;
++ }
++ rt_i2c_w32(msg->len - 1, REG_BYTECNT_REG);
++ for (i = 0; i < msg->len; i++) {
++ rt_i2c_w32(msg->buf[i], REG_DATAOUT_REG);
++ if(i == 0)
++ rt_i2c_w32(WRITE_CMD, REG_STARTXFR_REG);
++
++ if (rt_i2c_wait_tx_done())
++ goto ERR_TIMEOUT;
++ }
++ }
++
++ return 0;
++ERR_TIMEOUT:
++ return -ETIMEDOUT;
++}
++
++static int rt_i2c_master_xfer(struct i2c_adapter *a, struct i2c_msg *m, int n)
++{
++ int i = 0;
++ int ret = 0;
++ i2c_master_init();
++ mt7621_i2c_enable(m);
++
++ for (i = 0; i != n && ret==0; i++) {
++ ret = rt_i2c_handle_msg(a, &m[i]);
++
++ if (ret) {
++ return ret;
++ }
++ }
++
++ return i;
++}
++
++static u32 rt_i2c_func(struct i2c_adapter *a)
++{
++ return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
++}
++
++static const struct i2c_algorithm rt_i2c_algo = {
++ .master_xfer = rt_i2c_master_xfer,
++ .functionality = rt_i2c_func,
++};
++
++static int rt_i2c_probe(struct platform_device *pdev)
++{
++ struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
++ int ret;
++ struct i2c_algo_mt7621_data *adapter_data;
++
++ adapter = kzalloc(sizeof(struct i2c_adapter), GFP_KERNEL);
++ if (!adapter) {
++ dev_err(&pdev->dev, "failed to allocate i2c_adapter\n");
++ ret = -ENOMEM;
++ goto out;
++ }
++ adapter_data = kzalloc(sizeof(struct i2c_algo_mt7621_data), GFP_KERNEL);
++ if (!adapter_data) {
++ ret = -ENOMEM;
++ goto free_adapter;
++ }
++
++ membase = devm_request_and_ioremap(&pdev->dev, res);
++ if (IS_ERR(membase)){
++ ret = -EBUSY;
++ goto free_both;
++ }
++ memsysctlbase = membase - I2C_OFFSET;
++
++ adapter_data->id = i2c_id++;
++ strlcpy(adapter->name, dev_name(&pdev->dev), sizeof(adapter->name));
++
++ adapter->owner = THIS_MODULE;
++ adapter->nr = pdev->id;
++ adapter->timeout = HZ;
++ adapter->algo = &rt_i2c_algo;
++ adapter->class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
++ adapter->dev.parent = &pdev->dev;
++ adapter->dev.of_node = pdev->dev.of_node;
++
++ init_waitqueue_head(&adapter_data->waitq);
++ spin_lock_init(&adapter_data->lock);
++
++ platform_set_drvdata(pdev, adapter);
++ adapter->algo_data = adapter_data;
++
++ ret = i2c_add_numbered_adapter(adapter);
++ if (ret)
++ return ret;
++
++ printk("MT7621A i2c add adapter is ok\n");
++
++ return 0;
++free_both:
++ kfree(adapter_data);
++ free_adapter:
++ kfree(adapter);
++out:
++ return ret;
++}
++
++static int rt_i2c_remove(struct platform_device *pdev)
++{
++ struct i2c_algo_mt7621_data *adapter_data = (struct i2c_algo_mt7621_data *)adapter->algo_data;
++ release_mem_region((resource_size_t)membase,0x100);
++ kfree(adapter_data);
++ kfree(adapter);
++ platform_set_drvdata(pdev, NULL);
++
++ return 0;
++}
++
++static const struct of_device_id i2c_rt_dt_ids[] = {
++ { .compatible = "ralink,i2c-mt7621", },
++ { /* sentinel */ }
++};
++
++MODULE_DEVICE_TABLE(of, i2c_rt_dt_ids);
++
++static struct platform_driver rt_i2c_driver = {
++ .probe = rt_i2c_probe,
++ .remove = rt_i2c_remove,
++ .driver = {
++ .owner = THIS_MODULE,
++ .name = "i2c-mt7621",
++ .of_match_table = i2c_rt_dt_ids,
++ },
++};
++
++static int __init i2c_rt_init (void)
++{
++ return platform_driver_register(&rt_i2c_driver);
++}
++
++static void __exit i2c_rt_exit (void)
++{
++ platform_driver_unregister(&rt_i2c_driver);
++}
++module_init (i2c_rt_init);
++module_exit (i2c_rt_exit);
++
++MODULE_AUTHOR("Steven Liu <steven_liu@mediatek.com>");
++MODULE_DESCRIPTION("MT7621 I2c host driver");
++MODULE_LICENSE("GPL");
++MODULE_ALIAS("platform:MT7621-I2C");