[PATCH v5 2/3] I2C: mediatek: Add driver for MediaTek I2C controller

[Eddie Huang <eddie.huang@mediatek.com>]

From: Xudong Chen <xudong.chen@mediatek.com>

The mediatek SoCs have I2C controller that handle I2C transfer.
This patch include common I2C bus driver.
This driver is compatible with I2C controller on mt65xx/mt81xx.

Signed-off-by: Xudong Chen <xudong.chen@mediatek.com>
Signed-off-by: Liguo Zhang <liguo.zhang@mediatek.com>
Signed-off-by: Eddie Huang <eddie.huang@mediatek.com>
---
 drivers/i2c/busses/Kconfig      |   9 +
 drivers/i2c/busses/Makefile     |   1 +
 drivers/i2c/busses/i2c-mt65xx.c | 705 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 715 insertions(+)
 create mode 100644 drivers/i2c/busses/i2c-mt65xx.c

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 22da9c2..243c4ec 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -602,6 +602,15 @@ config I2C_MPC
 	  This driver can also be built as a module.  If so, the module
 	  will be called i2c-mpc.
 
+config I2C_MT65XX
+	tristate "MediaTek I2C adapter"
+	depends on ARCH_MEDIATEK || COMPILE_TEST
+	help
+	  This selects the MediaTek(R) Integrated Inter Circuit bus driver
+	  for MT65xx and MT81xx.
+	  If you want to use MediaTek(R) I2C interface, say Y or M here.
+	  If unsure, say N.
+
 config I2C_MV64XXX
 	tristate "Marvell mv64xxx I2C Controller"
 	depends on MV64X60 || PLAT_ORION || ARCH_SUNXI
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 3638feb..372a711 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -58,6 +58,7 @@ obj-$(CONFIG_I2C_IOP3XX)	+= i2c-iop3xx.o
 obj-$(CONFIG_I2C_KEMPLD)	+= i2c-kempld.o
 obj-$(CONFIG_I2C_MESON)		+= i2c-meson.o
 obj-$(CONFIG_I2C_MPC)		+= i2c-mpc.o
+obj-$(CONFIG_I2C_MT65XX)	+= i2c-mt65xx.o
 obj-$(CONFIG_I2C_MV64XXX)	+= i2c-mv64xxx.o
 obj-$(CONFIG_I2C_MXS)		+= i2c-mxs.o
 obj-$(CONFIG_I2C_NOMADIK)	+= i2c-nomadik.o
diff --git a/drivers/i2c/busses/i2c-mt65xx.c b/drivers/i2c/busses/i2c-mt65xx.c
new file mode 100644
index 0000000..3940112
--- /dev/null
+++ b/drivers/i2c/busses/i2c-mt65xx.c
@@ -0,0 +1,705 @@
+/*
+ * Copyright (c) 2014 MediaTek Inc.
+ * Author: Xudong.chen <xudong.chen@mediatek.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms 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.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/sched.h>
+#include <linux/delay.h>
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/device.h>
+#include <linux/platform_device.h>
+#include <linux/wait.h>
+#include <linux/mm.h>
+#include <linux/dma-mapping.h>
+#include <linux/scatterlist.h>
+#include <linux/io.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/clk.h>
+
+#define I2C_HS_NACKERR			(1 << 2)
+#define I2C_ACKERR			(1 << 1)
+#define I2C_TRANSAC_COMP		(1 << 0)
+#define I2C_TRANSAC_START		(1 << 0)
+#define I2C_TIMING_STEP_DIV_MASK	(0x3f << 0)
+#define I2C_TIMING_SAMPLE_COUNT_MASK	(0x7 << 0)
+#define I2C_TIMING_SAMPLE_DIV_MASK	(0x7 << 8)
+#define I2C_TIMING_DATA_READ_MASK	(0x7 << 12)
+#define I2C_DCM_DISABLE			0x0000
+#define I2C_IO_CONFIG_OPEN_DRAIN	0x0003
+#define I2C_IO_CONFIG_PUSH_PULL		0x0000
+#define I2C_SOFT_RST			0x0001
+#define I2C_FIFO_ADDR_CLR		0x0001
+#define I2C_DELAY_LEN			0x0002
+#define I2C_ST_START_CON		0x8001
+#define I2C_FS_START_CON		0x1800
+#define I2C_TIME_CLR_VALUE		0x0000
+#define I2C_TIME_DEFAULT_VALUE		0x0003
+#define I2C_FS_TIME_INIT_VALUE		0x1303
+#define I2C_WRRD_TRANAC_VALUE		0x0002
+#define I2C_RD_TRANAC_VALUE		0x0001
+
+#define I2C_DMA_CON_TX			0x0000
+#define I2C_DMA_CON_RX			0x0001
+#define I2C_DMA_START_EN		0x0001
+#define I2C_DMA_INT_FLAG_NONE		0x0000
+#define I2C_DMA_CLR_FLAG		0x0000
+
+#define I2C_DEFAUT_SPEED		100000	/* hz */
+#define MAX_FS_MODE_SPEED		400000
+#define MAX_HS_MODE_SPEED		3400000
+#define MAX_MSG_NUM_MT6577		1
+#define MAX_DMA_TRANS_SIZE_MT6577	255
+#define MAX_WRRD_TRANS_SIZE_MT6577	31
+#define MAX_SAMPLE_CNT_DIV		8
+#define MAX_STEP_CNT_DIV		64
+#define MAX_HS_STEP_CNT_DIV		8
+
+#define I2C_CONTROL_RS                  (0x1 << 1)
+#define I2C_CONTROL_DMA_EN              (0x1 << 2)
+#define I2C_CONTROL_CLK_EXT_EN          (0x1 << 3)
+#define I2C_CONTROL_DIR_CHANGE          (0x1 << 4)
+#define I2C_CONTROL_ACKERR_DET_EN       (0x1 << 5)
+#define I2C_CONTROL_TRANSFER_LEN_CHANGE (0x1 << 6)
+#define I2C_CONTROL_WRAPPER             (0x1 << 0)
+
+#define COMPAT_MT6577			(0x1 << 0)
+#define COMPAT_MT6589			(0x1 << 1)
+
+#define I2C_DRV_NAME		"mt-i2c"
+
+enum DMA_REGS_OFFSET {
+	OFFSET_INT_FLAG = 0x0,
+	OFFSET_INT_EN = 0x04,
+	OFFSET_EN = 0x08,
+	OFFSET_CON = 0x18,
+	OFFSET_TX_MEM_ADDR = 0x1c,
+	OFFSET_RX_MEM_ADDR = 0x20,
+	OFFSET_TX_LEN = 0x24,
+	OFFSET_RX_LEN = 0x28,
+};
+
+enum i2c_trans_st_rs {
+	I2C_TRANS_STOP = 0,
+	I2C_TRANS_REPEATED_START,
+};
+
+enum {
+	FS_MODE,
+	HS_MODE,
+};
+
+enum mtk_trans_op {
+	I2C_MASTER_WR = 1,
+	I2C_MASTER_RD,
+	I2C_MASTER_WRRD,
+};
+
+enum I2C_REGS_OFFSET {
+	OFFSET_DATA_PORT = 0x0,
+	OFFSET_SLAVE_ADDR = 0x04,
+	OFFSET_INTR_MASK = 0x08,
+	OFFSET_INTR_STAT = 0x0c,
+	OFFSET_CONTROL = 0x10,
+	OFFSET_TRANSFER_LEN = 0x14,
+	OFFSET_TRANSAC_LEN = 0x18,
+	OFFSET_DELAY_LEN = 0x1c,
+	OFFSET_TIMING = 0x20,
+	OFFSET_START = 0x24,
+	OFFSET_EXT_CONF = 0x28,
+	OFFSET_FIFO_STAT = 0x30,
+	OFFSET_FIFO_THRESH = 0x34,
+	OFFSET_FIFO_ADDR_CLR = 0x38,
+	OFFSET_IO_CONFIG = 0x40,
+	OFFSET_RSV_DEBUG = 0x44,
+	OFFSET_HS = 0x48,
+	OFFSET_SOFTRESET = 0x50,
+	OFFSET_DCM_EN = 0x54,
+	OFFSET_PATH_DIR = 0x60,
+	OFFSET_DEBUGSTAT = 0x64,
+	OFFSET_DEBUGCTRL = 0x68,
+	OFFSET_TRANSFER_LEN_AUX = 0x6c,
+};
+
+struct mtk_i2c_data {
+	unsigned int clk_frequency;	/* bus speed in Hz */
+	unsigned int flags;
+	unsigned int clk_src_div;
+};
+
+struct mtk_i2c {
+	struct i2c_adapter adap;	/* i2c host adapter */
+	struct device *dev;
+	wait_queue_head_t wait;		/* i2c transfer wait queue */
+
+	/* set in i2c probe */
+	void __iomem *base;		/* i2c base addr */
+	void __iomem *pdmabase;		/* dma base address*/
+	unsigned int irqnr;		/* i2c interrupt number */
+	struct clk *clk_main;		/* main clock for i2c bus */
+	struct clk *clk_dma;		/* DMA clock for i2c via DMA */
+	struct clk *clk_pmic;		/* PMIC clock for i2c from PMIC */
+	bool have_pmic;			/* can use i2c pins from PMIC */
+	bool use_push_pull;		/* IO config push-pull mode */
+	u32 platform_compat;		/* platform compatible data */
+
+	/* set when doing the transfer */
+	u16 irq_stat;			/* interrupt status */
+	spinlock_t irqlock;		/* interrupt lock */
+	unsigned int speed_hz;		/* The speed in transfer */
+	bool trans_stop;		/* i2c transfer stop */
+	enum mtk_trans_op op;
+	u16 timing_reg;
+	u16 high_speed_reg;
+};
+
+static const struct of_device_id mtk_i2c_of_match[] = {
+	{ .compatible = "mediatek,mt6577-i2c", .data = (void *)COMPAT_MT6577 },
+	{ .compatible = "mediatek,mt6589-i2c", .data = (void *)COMPAT_MT6589 },
+	{}
+};
+MODULE_DEVICE_TABLE(of, mtk_i2c_match);
+
+static inline void mtk_i2c_writew(u16 value, struct mtk_i2c *i2c, u8 offset)
+{
+	writew(value, i2c->base + offset);
+}
+
+static inline u16 mtk_i2c_readw(struct mtk_i2c *i2c, u8 offset)
+{
+	return readw(i2c->base + offset);
+}
+
+static inline void mtk_i2c_writel_dma(u32 value, struct mtk_i2c *i2c, u8 offset)
+{
+	writel(value, i2c->pdmabase + offset);
+}
+
+static int mtk_i2c_clock_enable(struct mtk_i2c *i2c)
+{
+	int ret;
+
+	ret = clk_prepare_enable(i2c->clk_dma);
+	if (ret)
+		return ret;
+
+	ret = clk_prepare_enable(i2c->clk_main);
+	if (ret)
+		goto err_main;
+
+	if (i2c->have_pmic) {
+		ret = clk_prepare_enable(i2c->clk_pmic);
+		if (ret)
+			goto err_pmic;
+	}
+	return 0;
+
+err_pmic:
+	clk_disable_unprepare(i2c->clk_main);
+err_main:
+	clk_disable_unprepare(i2c->clk_dma);
+
+	return ret;
+}
+
+static void mtk_i2c_clock_disable(struct mtk_i2c *i2c)
+{
+	if (i2c->have_pmic)
+		clk_disable_unprepare(i2c->clk_pmic);
+
+	clk_disable_unprepare(i2c->clk_main);
+	clk_disable_unprepare(i2c->clk_dma);
+}
+
+static inline void mtk_i2c_init_hw(struct mtk_i2c *i2c)
+{
+	mtk_i2c_writew(I2C_SOFT_RST, i2c, OFFSET_SOFTRESET);
+	/* Set ioconfig */
+	if (i2c->use_push_pull)
+		mtk_i2c_writew(I2C_IO_CONFIG_PUSH_PULL, i2c, OFFSET_IO_CONFIG);
+	else
+		mtk_i2c_writew(I2C_IO_CONFIG_OPEN_DRAIN, i2c, OFFSET_IO_CONFIG);
+
+	if (i2c->platform_compat & COMPAT_MT6577)
+		mtk_i2c_writew(I2C_DCM_DISABLE, i2c, OFFSET_DCM_EN);
+
+	mtk_i2c_writew(i2c->timing_reg, i2c, OFFSET_TIMING);
+	mtk_i2c_writew(i2c->high_speed_reg, i2c, OFFSET_HS);
+}
+
+/* calculate i2c port speed */
+static int i2c_set_speed(struct mtk_i2c *i2c, unsigned int clk_src_in_hz)
+{
+	int mode;
+	unsigned int khz;
+	unsigned int step_cnt;
+	unsigned int sample_cnt;
+	unsigned int sclk;
+	unsigned int hclk;
+	unsigned int max_step_cnt;
+	unsigned int sample_div = MAX_SAMPLE_CNT_DIV;
+	unsigned int step_div;
+	unsigned int min_div;
+	unsigned int best_mul;
+	unsigned int cnt_mul;
+
+	if (i2c->speed_hz > MAX_HS_MODE_SPEED) {
+		return -EINVAL;
+	} else if (i2c->speed_hz > MAX_FS_MODE_SPEED) {
+		mode = HS_MODE;
+		max_step_cnt = MAX_HS_STEP_CNT_DIV;
+	} else {
+		mode = FS_MODE;
+		max_step_cnt = MAX_STEP_CNT_DIV;
+	}
+
+	step_div = max_step_cnt;
+	/* Find the best combination */
+	khz = i2c->speed_hz / 1000;
+	hclk = clk_src_in_hz / 1000;
+	min_div = ((hclk >> 1) + khz - 1) / khz;
+	best_mul = MAX_SAMPLE_CNT_DIV * max_step_cnt;
+
+	for (sample_cnt = 1; sample_cnt <= MAX_SAMPLE_CNT_DIV; sample_cnt++) {
+		step_cnt = (min_div + sample_cnt - 1) / sample_cnt;
+		cnt_mul = step_cnt * sample_cnt;
+		if (step_cnt > max_step_cnt)
+			continue;
+
+		if (cnt_mul < best_mul) {
+			best_mul = cnt_mul;
+			sample_div = sample_cnt;
+			step_div = step_cnt;
+			if (best_mul == min_div)
+				break;
+		}
+	}
+
+	sample_cnt = sample_div;
+	step_cnt = step_div;
+	sclk = hclk / (2 * sample_cnt * step_cnt);
+	if (sclk > khz) {
+		dev_dbg(i2c->dev, "%s mode: unsupported speed (%ldkhz)\n",
+			(mode == HS_MODE) ? "HS" : "ST/FT", (long int)khz);
+		return -ENOTSUPP;
+	}
+
+	step_cnt--;
+	sample_cnt--;
+
+	if (mode == HS_MODE) {
+		/* Set the hign speed mode register */
+		i2c->timing_reg = I2C_FS_TIME_INIT_VALUE;
+		i2c->high_speed_reg = I2C_TIME_DEFAULT_VALUE |
+			(sample_cnt & I2C_TIMING_SAMPLE_COUNT_MASK) << 12 |
+			(step_cnt & I2C_TIMING_SAMPLE_COUNT_MASK) << 8;
+	} else {
+		i2c->timing_reg =
+			(sample_cnt & I2C_TIMING_SAMPLE_COUNT_MASK) << 8 |
+			(step_cnt & I2C_TIMING_STEP_DIV_MASK) << 0;
+		/* Disable the high speed transaction */
+		i2c->high_speed_reg = I2C_TIME_CLR_VALUE;
+	}
+
+	return 0;
+}
+
+static int mtk_i2c_do_transfer(struct mtk_i2c *i2c, struct i2c_msg *msgs)
+{
+	u16 addr_reg;
+	u16 control_reg;
+	u16 irqstat;
+	dma_addr_t rpaddr = 0;
+	dma_addr_t wpaddr = 0;
+	int tmo = i2c->adap.timeout;
+
+	i2c->trans_stop = false;
+	spin_lock(&i2c->irqlock);
+	i2c->irq_stat = 0;
+	spin_unlock(&i2c->irqlock);
+
+	/* If use i2c pin from PMIC mt6397 side, need set PATH_DIR first */
+	if (i2c->have_pmic)
+		mtk_i2c_writew(I2C_CONTROL_WRAPPER, i2c, OFFSET_PATH_DIR);
+
+	control_reg = I2C_CONTROL_ACKERR_DET_EN |
+		I2C_CONTROL_CLK_EXT_EN | I2C_CONTROL_DMA_EN;
+	if (i2c->speed_hz > 400000)
+		control_reg |= I2C_CONTROL_RS;
+	if (i2c->op == I2C_MASTER_WRRD)
+		control_reg |= I2C_CONTROL_DIR_CHANGE | I2C_CONTROL_RS;
+	mtk_i2c_writew(control_reg, i2c, OFFSET_CONTROL);
+
+	/* set start condition */
+	if (i2c->speed_hz <= 100000)
+		mtk_i2c_writew(I2C_ST_START_CON, i2c, OFFSET_EXT_CONF);
+	else
+		mtk_i2c_writew(I2C_FS_START_CON, i2c, OFFSET_EXT_CONF);
+
+	if (~control_reg & I2C_CONTROL_RS)
+		mtk_i2c_writew(I2C_DELAY_LEN, i2c, OFFSET_DELAY_LEN);
+
+	addr_reg = msgs->addr << 1;
+	if (i2c->op == I2C_MASTER_RD)
+		addr_reg |= 0x1;
+	mtk_i2c_writew(addr_reg, i2c, OFFSET_SLAVE_ADDR);
+
+	/* Clear interrupt status */
+	mtk_i2c_writew(I2C_HS_NACKERR | I2C_ACKERR | I2C_TRANSAC_COMP,
+		i2c, OFFSET_INTR_STAT);
+	mtk_i2c_writew(I2C_FIFO_ADDR_CLR, i2c, OFFSET_FIFO_ADDR_CLR);
+
+	/* Enable interrupt */
+	mtk_i2c_writew(I2C_HS_NACKERR | I2C_ACKERR | I2C_TRANSAC_COMP,
+		i2c, OFFSET_INTR_MASK);
+
+	/* Set transfer and transaction len */
+	if (i2c->op == I2C_MASTER_WRRD) {
+		mtk_i2c_writew(msgs->len | ((msgs + 1)->len) << 8,
+			i2c, OFFSET_TRANSFER_LEN);
+		mtk_i2c_writew(I2C_WRRD_TRANAC_VALUE, i2c, OFFSET_TRANSAC_LEN);
+	} else {
+		mtk_i2c_writew(msgs->len, i2c, OFFSET_TRANSFER_LEN);
+		mtk_i2c_writew(I2C_RD_TRANAC_VALUE, i2c, OFFSET_TRANSAC_LEN);
+	}
+
+	/* Prepare buffer data to start transfer */
+	if (i2c->op == I2C_MASTER_RD) {
+		mtk_i2c_writel_dma(I2C_DMA_INT_FLAG_NONE, i2c, OFFSET_INT_FLAG);
+		mtk_i2c_writel_dma(I2C_DMA_CON_RX, i2c, OFFSET_CON);
+		rpaddr = dma_map_single(i2c->adap.dev.parent, msgs->buf,
+						msgs->len, DMA_FROM_DEVICE);
+		if (dma_mapping_error(i2c->adap.dev.parent, rpaddr))
+			return -ENOMEM;
+		mtk_i2c_writel_dma((u32)rpaddr, i2c, OFFSET_RX_MEM_ADDR);
+		mtk_i2c_writel_dma(msgs->len, i2c, OFFSET_RX_LEN);
+	} else if (i2c->op == I2C_MASTER_WR) {
+		mtk_i2c_writel_dma(I2C_DMA_INT_FLAG_NONE, i2c, OFFSET_INT_FLAG);
+		mtk_i2c_writel_dma(I2C_DMA_CON_TX, i2c, OFFSET_CON);
+		wpaddr = dma_map_single(i2c->adap.dev.parent, msgs->buf,
+						msgs->len, DMA_TO_DEVICE);
+		if (dma_mapping_error(i2c->adap.dev.parent, wpaddr))
+			return -ENOMEM;
+		mtk_i2c_writel_dma((u32)wpaddr, i2c, OFFSET_TX_MEM_ADDR);
+		mtk_i2c_writel_dma(msgs->len, i2c, OFFSET_TX_LEN);
+	} else {
+		mtk_i2c_writel_dma(I2C_DMA_CLR_FLAG, i2c, OFFSET_INT_FLAG);
+		mtk_i2c_writel_dma(I2C_DMA_CLR_FLAG, i2c, OFFSET_CON);
+		wpaddr = dma_map_single(i2c->adap.dev.parent, msgs->buf,
+						msgs->len, DMA_TO_DEVICE);
+		if (dma_mapping_error(i2c->adap.dev.parent, wpaddr))
+			return -ENOMEM;
+		rpaddr = dma_map_single(i2c->adap.dev.parent, (msgs + 1)->buf,
+						(msgs + 1)->len,
+						DMA_FROM_DEVICE);
+		if (dma_mapping_error(i2c->adap.dev.parent, rpaddr)) {
+			dma_unmap_single(i2c->adap.dev.parent, wpaddr,
+						msgs->len, DMA_TO_DEVICE);
+			return -ENOMEM;
+		}
+		mtk_i2c_writel_dma((u32)wpaddr, i2c, OFFSET_TX_MEM_ADDR);
+		mtk_i2c_writel_dma((u32)rpaddr, i2c, OFFSET_RX_MEM_ADDR);
+		mtk_i2c_writel_dma(msgs->len, i2c, OFFSET_TX_LEN);
+		mtk_i2c_writel_dma((msgs + 1)->len, i2c, OFFSET_RX_LEN);
+	}
+
+	/* flush before sending start */
+	mb();
+	mtk_i2c_writel_dma(I2C_DMA_START_EN, i2c, OFFSET_EN);
+	mtk_i2c_writew(I2C_TRANSAC_START, i2c, OFFSET_START);
+
+	tmo = wait_event_timeout(i2c->wait, i2c->trans_stop, tmo);
+
+	if (i2c->op == I2C_MASTER_WR) {
+		dma_unmap_single(i2c->adap.dev.parent, wpaddr,
+					msgs->len, DMA_TO_DEVICE);
+	} else if (i2c->op == I2C_MASTER_RD) {
+		dma_unmap_single(i2c->adap.dev.parent, rpaddr,
+					msgs->len, DMA_FROM_DEVICE);
+	} else {
+		dma_unmap_single(i2c->adap.dev.parent, wpaddr, msgs->len,
+					DMA_TO_DEVICE);
+		dma_unmap_single(i2c->adap.dev.parent, rpaddr, (msgs + 1)->len,
+					DMA_FROM_DEVICE);
+	}
+
+	if (!i2c->trans_stop && tmo == 0) {
+		dev_dbg(i2c->dev, "addr: %x, transfer timeout\n", msgs->addr);
+		mtk_i2c_init_hw(i2c);
+		return -ETIMEDOUT;
+	}
+
+	spin_lock(&i2c->irqlock);
+	irqstat = i2c->irq_stat;
+	spin_unlock(&i2c->irqlock);
+
+	if (irqstat & (I2C_HS_NACKERR | I2C_ACKERR)) {
+		dev_dbg(i2c->dev, "addr: %x, transfer ACK error\n", msgs->addr);
+		mtk_i2c_init_hw(i2c);
+		return -EREMOTEIO;
+	}
+
+	return 0;
+}
+
+static int mtk_i2c_transfer(struct i2c_adapter *adap,
+	struct i2c_msg msgs[], int num)
+{
+	int ret;
+	int left_num = num;
+	struct mtk_i2c *i2c = i2c_get_adapdata(adap);
+
+	ret = mtk_i2c_clock_enable(i2c);
+	if (ret)
+		return ret;
+
+	if (msgs->buf == NULL) {
+		dev_dbg(i2c->dev, "data buffer is NULL.\n");
+		ret = -EINVAL;
+		goto err_exit;
+	}
+
+	if (msgs->flags & I2C_M_RD)
+		i2c->op = I2C_MASTER_RD;
+	else
+		i2c->op = I2C_MASTER_WR;
+
+	if (num > 1) {
+		/* combined two messages into one transaction */
+		i2c->op = I2C_MASTER_WRRD;
+		left_num--;
+	}
+
+	/* always use DMA mode. */
+	ret = mtk_i2c_do_transfer(i2c, msgs);
+	if (ret < 0)
+		goto err_exit;
+
+	/* the return value is number of executed messages */
+	ret = num;
+
+err_exit:
+	mtk_i2c_clock_disable(i2c);
+	return ret;
+}
+
+static irqreturn_t mtk_i2c_irq(int irqno, void *dev_id)
+{
+	struct mtk_i2c *i2c = dev_id;
+
+	/* Clear interrupt mask */
+	mtk_i2c_writew(~(I2C_HS_NACKERR | I2C_ACKERR | I2C_TRANSAC_COMP),
+		i2c, OFFSET_INTR_MASK);
+
+	spin_lock(&i2c->irqlock);
+	i2c->irq_stat = mtk_i2c_readw(i2c, OFFSET_INTR_STAT);
+	i2c->trans_stop = true;
+	spin_unlock(&i2c->irqlock);
+	mtk_i2c_writew(I2C_HS_NACKERR | I2C_ACKERR
+			| I2C_TRANSAC_COMP, i2c, OFFSET_INTR_STAT);
+	wake_up(&i2c->wait);
+
+	return IRQ_HANDLED;
+}
+
+static u32 mtk_i2c_functionality(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static const struct i2c_algorithm mtk_i2c_algorithm = {
+	.master_xfer = mtk_i2c_transfer,
+	.functionality = mtk_i2c_functionality,
+};
+
+static inline unsigned long mtk_get_device_prop(struct platform_device *pdev)
+{
+	const struct of_device_id *match;
+
+	match = of_match_node(mtk_i2c_of_match, pdev->dev.of_node);
+	return (unsigned long)match->data;
+}
+
+static int mtk_i2c_parse_dt(struct device_node *np, struct mtk_i2c *i2c,
+	unsigned int *clk_src_div)
+{
+	int ret;
+
+	i2c->speed_hz = I2C_DEFAUT_SPEED;
+	ret = of_property_read_u32(np, "clock-frequency", &i2c->speed_hz);
+	if (ret < 0)
+		return ret;
+
+	ret = of_property_read_u32(np, "clock-div", clk_src_div);
+	if (ret < 0)
+		return ret;
+
+	if (*clk_src_div == 0)
+		return -EINVAL;
+
+	i2c->have_pmic = of_property_read_bool(np, "mediatek,have-pmic");
+	i2c->use_push_pull =
+		of_property_read_bool(np, "mediatek,use-push-pull");
+
+	return 0;
+}
+
+static const struct i2c_adapter_quirks mt6577_i2c_quirks = {
+	.flags = I2C_AQ_COMB_WRITE_THEN_READ,
+	.max_num_msgs = MAX_MSG_NUM_MT6577,
+	.max_write_len = MAX_DMA_TRANS_SIZE_MT6577,
+	.max_read_len = MAX_DMA_TRANS_SIZE_MT6577,
+	.max_comb_1st_msg_len = MAX_DMA_TRANS_SIZE_MT6577,
+	.max_comb_2nd_msg_len = MAX_WRRD_TRANS_SIZE_MT6577,
+};
+
+static int mtk_i2c_probe(struct platform_device *pdev)
+{
+	int ret = 0;
+	struct mtk_i2c *i2c;
+	struct clk *clk;
+	unsigned int clk_src_in_hz;
+	unsigned int clk_src_div;
+	struct resource *res;
+
+	i2c = devm_kzalloc(&pdev->dev, sizeof(struct mtk_i2c), GFP_KERNEL);
+	if (i2c == NULL)
+		return -ENOMEM;
+
+	ret = mtk_i2c_parse_dt(pdev->dev.of_node, i2c, &clk_src_div);
+	if (ret)
+		return -EINVAL;
+
+	i2c->platform_compat = mtk_get_device_prop(pdev);
+	if (i2c->have_pmic && (i2c->platform_compat & COMPAT_MT6577))
+		return -EINVAL;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+
+	i2c->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(i2c->base))
+		return PTR_ERR(i2c->base);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+
+	i2c->pdmabase = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(i2c->pdmabase))
+		return PTR_ERR(i2c->pdmabase);
+
+	i2c->irqnr = platform_get_irq(pdev, 0);
+	if (i2c->irqnr <= 0)
+		return -EINVAL;
+
+	spin_lock_init(&i2c->irqlock);
+
+	i2c->adap.dev.of_node = pdev->dev.of_node;
+	i2c->dev = &i2c->adap.dev;
+	i2c->adap.dev.parent = &pdev->dev;
+	i2c->adap.owner = THIS_MODULE;
+	i2c->adap.algo = &mtk_i2c_algorithm;
+	i2c->adap.quirks = &mt6577_i2c_quirks;
+	i2c->adap.timeout = 2 * HZ;
+	i2c->adap.retries = 1;
+
+	i2c->clk_main = devm_clk_get(&pdev->dev, "main");
+	if (IS_ERR(i2c->clk_main)) {
+		dev_err(&pdev->dev, "cannot get main clock\n");
+		return PTR_ERR(i2c->clk_main);
+	}
+
+	i2c->clk_dma = devm_clk_get(&pdev->dev, "dma");
+	if (IS_ERR(i2c->clk_dma)) {
+		dev_err(&pdev->dev, "cannot get dma clock\n");
+		return PTR_ERR(i2c->clk_dma);
+	}
+
+	clk = i2c->clk_main;
+	if (i2c->have_pmic) {
+		i2c->clk_pmic = devm_clk_get(&pdev->dev, "pmic");
+		if (IS_ERR(i2c->clk_pmic)) {
+			dev_err(&pdev->dev, "cannot get pmic clock\n");
+			return PTR_ERR(i2c->clk_pmic);
+		}
+		clk = i2c->clk_pmic;
+	}
+	clk_src_in_hz = clk_get_rate(clk) / clk_src_div;
+
+	dev_dbg(&pdev->dev, "clock source %p,clock src frequency %d\n",
+		i2c->clk_main, clk_src_in_hz);
+	strlcpy(i2c->adap.name, I2C_DRV_NAME, sizeof(i2c->adap.name));
+	init_waitqueue_head(&i2c->wait);
+
+	ret = i2c_set_speed(i2c, clk_src_in_hz);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to set the speed.\n");
+		return -EINVAL;
+	}
+
+	ret = mtk_i2c_clock_enable(i2c);
+	if (ret) {
+		dev_err(&pdev->dev, "clock enable failed!\n");
+		return ret;
+	}
+	mtk_i2c_init_hw(i2c);
+	mtk_i2c_clock_disable(i2c);
+
+	ret = devm_request_irq(&pdev->dev, i2c->irqnr, mtk_i2c_irq,
+		IRQF_TRIGGER_NONE, I2C_DRV_NAME, i2c);
+	if (ret < 0) {
+		dev_err(&pdev->dev,
+			"Request I2C IRQ %d fail\n", i2c->irqnr);
+		return ret;
+	}
+
+	i2c_set_adapdata(&i2c->adap, i2c);
+	ret = i2c_add_adapter(&i2c->adap);
+	if (ret) {
+		dev_err(&pdev->dev, "Failed to add i2c bus to i2c core\n");
+		return ret;
+	}
+
+	platform_set_drvdata(pdev, i2c);
+
+	return 0;
+}
+
+static int mtk_i2c_remove(struct platform_device *pdev)
+{
+	struct mtk_i2c *i2c = platform_get_drvdata(pdev);
+
+	i2c_del_adapter(&i2c->adap);
+	platform_set_drvdata(pdev, NULL);
+
+	return 0;
+}
+
+static struct platform_driver mtk_i2c_driver = {
+	.probe = mtk_i2c_probe,
+	.remove = mtk_i2c_remove,
+	.driver = {
+		.name = I2C_DRV_NAME,
+		.of_match_table = of_match_ptr(mtk_i2c_of_match),
+	},
+};
+
+module_platform_driver(mtk_i2c_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("MediaTek I2C Bus Driver");
+MODULE_AUTHOR("Xudong Chen <xudong.chen@mediatek.com>");
-- 
1.8.1.1.dirty