drivers/i2c/busses/i2c-mt7621.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * drivers/i2c/busses/i2c-mt7621.c
  *
  * Copyright (C) 2013 Steven Liu <steven_liu@mediatek.com>
  * Copyright (C) 2016 Michael Lee <igvtee@gmail.com>
  * Copyright (C) 2018 Jan Breuer <jan.breuer@jaybee.cz>
  *
  * Improve driver for i2cdetect from i2c-tools to detect i2c devices on the bus.
  * (C) 2014 Sittisak <sittisaks@hotmail.com>
  */

 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/i2c.h>
 #include <linux/io.h>
 #include <linux/iopoll.h>
 #include <linux/module.h>
 #include <linux/of_platform.h>
 #include <linux/reset.h>

 #define REG_SM0CFG2_REG		0x28
 #define REG_SM0CTL0_REG		0x40
 #define REG_SM0CTL1_REG		0x44
 #define REG_SM0D0_REG		0x50
 #define REG_SM0D1_REG		0x54
 #define REG_PINTEN_REG		0x5c
 #define REG_PINTST_REG		0x60
 #define REG_PINTCL_REG		0x64

 /* REG_SM0CFG2_REG */
 #define SM0CFG2_IS_AUTOMODE	BIT(0)

 /* REG_SM0CTL0_REG */
 #define SM0CTL0_ODRAIN		BIT(31)
 #define SM0CTL0_CLK_DIV_MASK	(0x7ff << 16)
 #define SM0CTL0_CLK_DIV_MAX	0x7ff
 #define SM0CTL0_CS_STATUS       BIT(4)
 #define SM0CTL0_SCL_STATE       BIT(3)
 #define SM0CTL0_SDA_STATE       BIT(2)
 #define SM0CTL0_EN              BIT(1)
 #define SM0CTL0_SCL_STRETCH     BIT(0)

 /* REG_SM0CTL1_REG */
 #define SM0CTL1_ACK_MASK	(0xff << 16)
 #define SM0CTL1_PGLEN_MASK	(0x7 << 8)
 #define SM0CTL1_PGLEN(x)	((((x) - 1) << 8) & SM0CTL1_PGLEN_MASK)
 #define SM0CTL1_READ		(5 << 4)
 #define SM0CTL1_READ_LAST	(4 << 4)
 #define SM0CTL1_STOP		(3 << 4)
 #define SM0CTL1_WRITE		(2 << 4)
 #define SM0CTL1_START		(1 << 4)
 #define SM0CTL1_MODE_MASK	(0x7 << 4)
 #define SM0CTL1_TRI		BIT(0)

 /* timeout waiting for I2C devices to respond */
 #define TIMEOUT_MS		1000

 struct mtk_i2c {
 	void __iomem *base;
 	struct device *dev;
 	struct i2c_adapter adap;
 	u32 bus_freq;
 	u32 clk_div;
 	u32 flags;
 	struct clk *clk;
 };

 static int mtk_i2c_wait_idle(struct mtk_i2c *i2c)
 {
 	int ret;
 	u32 val;

 	ret = readl_relaxed_poll_timeout(i2c->base + REG_SM0CTL1_REG,
 					 val, !(val & SM0CTL1_TRI),
 					 10, TIMEOUT_MS * 1000);
 	if (ret)
 		dev_dbg(i2c->dev, "idle err(%d)\n", ret);

 	return ret;
 }

 static void mtk_i2c_reset(struct mtk_i2c *i2c)
 {
 	int ret;

 	ret = device_reset(i2c->adap.dev.parent);
 	if (ret)
 		dev_err(i2c->dev, "I2C reset failed!\n");

 	/*
 	 * Don't set SM0CTL0_ODRAIN as its bit meaning is inverted. To
 	 * configure open-drain mode, this bit needs to be cleared.
 	 */
 	iowrite32(((i2c->clk_div << 16) & SM0CTL0_CLK_DIV_MASK) | SM0CTL0_EN |
 		  SM0CTL0_SCL_STRETCH, i2c->base + REG_SM0CTL0_REG);
 	iowrite32(0, i2c->base + REG_SM0CFG2_REG);
 }

 static void mtk_i2c_dump_reg(struct mtk_i2c *i2c)
 {
 	dev_dbg(i2c->dev,
 		"SM0CFG2 %08x, SM0CTL0 %08x, SM0CTL1 %08x, SM0D0 %08x, SM0D1 %08x\n",
 		ioread32(i2c->base + REG_SM0CFG2_REG),
 		ioread32(i2c->base + REG_SM0CTL0_REG),
 		ioread32(i2c->base + REG_SM0CTL1_REG),
 		ioread32(i2c->base + REG_SM0D0_REG),
 		ioread32(i2c->base + REG_SM0D1_REG));
 }

 static int mtk_i2c_check_ack(struct mtk_i2c *i2c, u32 expected)
 {
 	u32 ack = readl_relaxed(i2c->base + REG_SM0CTL1_REG);
 	u32 ack_expected = (expected << 16) & SM0CTL1_ACK_MASK;

 	return ((ack & ack_expected) == ack_expected) ? 0 : -ENXIO;
 }

 static int mtk_i2c_master_start(struct mtk_i2c *i2c)
 {
 	iowrite32(SM0CTL1_START | SM0CTL1_TRI, i2c->base + REG_SM0CTL1_REG);
 	return mtk_i2c_wait_idle(i2c);
 }

 static int mtk_i2c_master_stop(struct mtk_i2c *i2c)
 {
 	iowrite32(SM0CTL1_STOP | SM0CTL1_TRI, i2c->base + REG_SM0CTL1_REG);
 	return mtk_i2c_wait_idle(i2c);
 }

 static int mtk_i2c_master_cmd(struct mtk_i2c *i2c, u32 cmd, int page_len)
 {
 	iowrite32(cmd | SM0CTL1_TRI | SM0CTL1_PGLEN(page_len),
 		  i2c->base + REG_SM0CTL1_REG);
 	return mtk_i2c_wait_idle(i2c);
 }

 static int mtk_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 			       int num)
 {
 	struct mtk_i2c *i2c;
 	struct i2c_msg *pmsg;
 	u16 addr;
 	int i, j, ret, len, page_len;
 	u32 cmd;
 	u32 data[2];

 	i2c = i2c_get_adapdata(adap);

 	for (i = 0; i < num; i++) {
 		pmsg = &msgs[i];

 		/* wait hardware idle */
 		ret = mtk_i2c_wait_idle(i2c);
 		if (ret)
 			goto err_timeout;

 		/* start sequence */
 		ret = mtk_i2c_master_start(i2c);
 		if (ret)
 			goto err_timeout;

 		/* write address */
 		if (pmsg->flags & I2C_M_TEN) {
 			/* 10 bits address */
 			addr = 0xf0 | ((pmsg->addr >> 7) & 0x06);
 			addr |= (pmsg->addr & 0xff) << 8;
 			if (pmsg->flags & I2C_M_RD)
 				addr |= 1;
 			iowrite32(addr, i2c->base + REG_SM0D0_REG);
 			ret = mtk_i2c_master_cmd(i2c, SM0CTL1_WRITE, 2);
 			if (ret)
 				goto err_timeout;
 		} else {
 			/* 7 bits address */
 			addr = i2c_8bit_addr_from_msg(pmsg);
 			iowrite32(addr, i2c->base + REG_SM0D0_REG);
 			ret = mtk_i2c_master_cmd(i2c, SM0CTL1_WRITE, 1);
 			if (ret)
 				goto err_timeout;
 		}

 		/* check address ACK */
 		if (!(pmsg->flags & I2C_M_IGNORE_NAK)) {
 			ret = mtk_i2c_check_ack(i2c, BIT(0));
 			if (ret)
 				goto err_ack;
 		}

 		/* transfer data */
 		for (len = pmsg->len, j = 0; len > 0; len -= 8, j += 8) {
 			page_len = (len >= 8) ? 8 : len;

 			if (pmsg->flags & I2C_M_RD) {
 				cmd = (len > 8) ?
 					SM0CTL1_READ : SM0CTL1_READ_LAST;
 			} else {
 				memcpy(data, &pmsg->buf[j], page_len);
 				iowrite32(data[0], i2c->base + REG_SM0D0_REG);
 				iowrite32(data[1], i2c->base + REG_SM0D1_REG);
 				cmd = SM0CTL1_WRITE;
 			}

 			ret = mtk_i2c_master_cmd(i2c, cmd, page_len);
 			if (ret)
 				goto err_timeout;

 			if (pmsg->flags & I2C_M_RD) {
 				data[0] = ioread32(i2c->base + REG_SM0D0_REG);
 				data[1] = ioread32(i2c->base + REG_SM0D1_REG);
 				memcpy(&pmsg->buf[j], data, page_len);
 			} else {
 				if (!(pmsg->flags & I2C_M_IGNORE_NAK)) {
 					ret = mtk_i2c_check_ack(i2c,
 								(1 << page_len)
 								- 1);
 					if (ret)
 						goto err_ack;
 				}
 			}
 		}
 	}

 	ret = mtk_i2c_master_stop(i2c);
 	if (ret)
 		goto err_timeout;

 	/* the return value is number of executed messages */
 	return i;

 err_ack:
 	ret = mtk_i2c_master_stop(i2c);
 	if (ret)
 		goto err_timeout;
 	return -ENXIO;

 err_timeout:
 	mtk_i2c_dump_reg(i2c);
 	mtk_i2c_reset(i2c);
 	return ret;
 }

 static u32 mtk_i2c_func(struct i2c_adapter *a)
 {
 	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_PROTOCOL_MANGLING;
 }

 static const struct i2c_algorithm mtk_i2c_algo = {
 	.master_xfer	= mtk_i2c_master_xfer,
 	.functionality	= mtk_i2c_func,
 };

 static const struct of_device_id i2c_mtk_dt_ids[] = {
 	{ .compatible = "mediatek,mt7621-i2c" },
 	{ /* sentinel */ }
 };

 MODULE_DEVICE_TABLE(of, i2c_mtk_dt_ids);

 static void mtk_i2c_init(struct mtk_i2c *i2c)
 {
 	i2c->clk_div = clk_get_rate(i2c->clk) / i2c->bus_freq - 1;
 	if (i2c->clk_div < 99)
 		i2c->clk_div = 99;
 	if (i2c->clk_div > SM0CTL0_CLK_DIV_MAX)
 		i2c->clk_div = SM0CTL0_CLK_DIV_MAX;

 	mtk_i2c_reset(i2c);
 }

 static int mtk_i2c_probe(struct platform_device *pdev)
 {
 	struct resource *res;
 	struct mtk_i2c *i2c;
 	struct i2c_adapter *adap;
 	int ret;

 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

 	i2c = devm_kzalloc(&pdev->dev, sizeof(struct mtk_i2c), GFP_KERNEL);
 	if (!i2c)
 		return -ENOMEM;

 	i2c->base = devm_ioremap_resource(&pdev->dev, res);
 	if (IS_ERR(i2c->base))
 		return PTR_ERR(i2c->base);

 	i2c->clk = devm_clk_get(&pdev->dev, NULL);
 	if (IS_ERR(i2c->clk)) {
 		dev_err(&pdev->dev, "no clock defined\n");
 		return PTR_ERR(i2c->clk);
 	}
 	ret = clk_prepare_enable(i2c->clk);
 	if (ret) {
 		dev_err(&pdev->dev, "Unable to enable clock\n");
 		return ret;
 	}

 	i2c->dev = &pdev->dev;

 	if (of_property_read_u32(pdev->dev.of_node, "clock-frequency",
 				 &i2c->bus_freq))
 		i2c->bus_freq = 100000;

 	if (i2c->bus_freq == 0) {
 		dev_warn(i2c->dev, "clock-frequency 0 not supported\n");
 		return -EINVAL;
 	}

 	adap = &i2c->adap;
 	adap->owner = THIS_MODULE;
 	adap->algo = &mtk_i2c_algo;
 	adap->retries = 3;
 	adap->dev.parent = &pdev->dev;
 	i2c_set_adapdata(adap, i2c);
 	adap->dev.of_node = pdev->dev.of_node;
 	strlcpy(adap->name, dev_name(&pdev->dev), sizeof(adap->name));

 	platform_set_drvdata(pdev, i2c);

 	mtk_i2c_init(i2c);

 	ret = i2c_add_adapter(adap);
 	if (ret < 0)
 		return ret;

 	dev_info(&pdev->dev, "clock %u kHz\n", i2c->bus_freq / 1000);

 	return ret;
 }

 static int mtk_i2c_remove(struct platform_device *pdev)
 {
 	struct mtk_i2c *i2c = platform_get_drvdata(pdev);

 	clk_disable_unprepare(i2c->clk);
 	i2c_del_adapter(&i2c->adap);

 	return 0;
 }

 static struct platform_driver mtk_i2c_driver = {
 	.probe		= mtk_i2c_probe,
 	.remove		= mtk_i2c_remove,
 	.driver		= {
 		.name	= "i2c-mt7621",
 		.of_match_table = i2c_mtk_dt_ids,
 	},
 };

 module_platform_driver(mtk_i2c_driver);

 MODULE_AUTHOR("Steven Liu");
 MODULE_DESCRIPTION("MT7621 I2C host driver");
 MODULE_LICENSE("GPL v2");
 MODULE_ALIAS("platform:MT7621-I2C");
	// SPDX-License-Identifier: GPL-2.0
	/*
	* drivers/i2c/busses/i2c-mt7621.c
	*
	* Copyright (C) 2013 Steven Liu <steven_liu@mediatek.com>
	* Copyright (C) 2016 Michael Lee <igvtee@gmail.com>
	* Copyright (C) 2018 Jan Breuer <jan.breuer@jaybee.cz>
	*
	* Improve driver for i2cdetect from i2c-tools to detect i2c devices on the bus.
	* (C) 2014 Sittisak <sittisaks@hotmail.com>
	*/

	#include <linux/clk.h>
	#include <linux/delay.h>
	#include <linux/i2c.h>
	#include <linux/io.h>
	#include <linux/iopoll.h>
	#include <linux/module.h>
	#include <linux/of_platform.h>
	#include <linux/reset.h>

	#define REG_SM0CFG2_REG 0x28
	#define REG_SM0CTL0_REG 0x40
	#define REG_SM0CTL1_REG 0x44
	#define REG_SM0D0_REG 0x50
	#define REG_SM0D1_REG 0x54
	#define REG_PINTEN_REG 0x5c
	#define REG_PINTST_REG 0x60
	#define REG_PINTCL_REG 0x64

	/* REG_SM0CFG2_REG */
	#define SM0CFG2_IS_AUTOMODE BIT(0)

	/* REG_SM0CTL0_REG */
	#define SM0CTL0_ODRAIN BIT(31)
	#define SM0CTL0_CLK_DIV_MASK (0x7ff << 16)
	#define SM0CTL0_CLK_DIV_MAX 0x7ff
	#define SM0CTL0_CS_STATUS BIT(4)
	#define SM0CTL0_SCL_STATE BIT(3)
	#define SM0CTL0_SDA_STATE BIT(2)
	#define SM0CTL0_EN BIT(1)
	#define SM0CTL0_SCL_STRETCH BIT(0)

	/* REG_SM0CTL1_REG */
	#define SM0CTL1_ACK_MASK (0xff << 16)
	#define SM0CTL1_PGLEN_MASK (0x7 << 8)
	#define SM0CTL1_PGLEN(x) ((((x) - 1) << 8) & SM0CTL1_PGLEN_MASK)
	#define SM0CTL1_READ (5 << 4)
	#define SM0CTL1_READ_LAST (4 << 4)
	#define SM0CTL1_STOP (3 << 4)
	#define SM0CTL1_WRITE (2 << 4)
	#define SM0CTL1_START (1 << 4)
	#define SM0CTL1_MODE_MASK (0x7 << 4)
	#define SM0CTL1_TRI BIT(0)

	/* timeout waiting for I2C devices to respond */
	#define TIMEOUT_MS 1000

	struct mtk_i2c {
	void __iomem *base;
	struct device *dev;
	struct i2c_adapter adap;
	u32 bus_freq;
	u32 clk_div;
	u32 flags;
	struct clk *clk;
	};

	static int mtk_i2c_wait_idle(struct mtk_i2c *i2c)
	{
	int ret;
	u32 val;

	ret = readl_relaxed_poll_timeout(i2c->base + REG_SM0CTL1_REG,
	val, !(val & SM0CTL1_TRI),
	10, TIMEOUT_MS * 1000);
	if (ret)
	dev_dbg(i2c->dev, "idle err(%d)\n", ret);

	return ret;
	}

	static void mtk_i2c_reset(struct mtk_i2c *i2c)
	{
	int ret;

	ret = device_reset(i2c->adap.dev.parent);
	if (ret)
	dev_err(i2c->dev, "I2C reset failed!\n");

	/*
	* Don't set SM0CTL0_ODRAIN as its bit meaning is inverted. To
	* configure open-drain mode, this bit needs to be cleared.
	*/
	iowrite32(((i2c->clk_div << 16) & SM0CTL0_CLK_DIV_MASK) \| SM0CTL0_EN \|
	SM0CTL0_SCL_STRETCH, i2c->base + REG_SM0CTL0_REG);
	iowrite32(0, i2c->base + REG_SM0CFG2_REG);
	}

	static void mtk_i2c_dump_reg(struct mtk_i2c *i2c)
	{
	dev_dbg(i2c->dev,
	"SM0CFG2 %08x, SM0CTL0 %08x, SM0CTL1 %08x, SM0D0 %08x, SM0D1 %08x\n",
	ioread32(i2c->base + REG_SM0CFG2_REG),
	ioread32(i2c->base + REG_SM0CTL0_REG),
	ioread32(i2c->base + REG_SM0CTL1_REG),
	ioread32(i2c->base + REG_SM0D0_REG),
	ioread32(i2c->base + REG_SM0D1_REG));
	}

	static int mtk_i2c_check_ack(struct mtk_i2c *i2c, u32 expected)
	{
	u32 ack = readl_relaxed(i2c->base + REG_SM0CTL1_REG);
	u32 ack_expected = (expected << 16) & SM0CTL1_ACK_MASK;

	return ((ack & ack_expected) == ack_expected) ? 0 : -ENXIO;
	}

	static int mtk_i2c_master_start(struct mtk_i2c *i2c)
	{
	iowrite32(SM0CTL1_START \| SM0CTL1_TRI, i2c->base + REG_SM0CTL1_REG);
	return mtk_i2c_wait_idle(i2c);
	}

	static int mtk_i2c_master_stop(struct mtk_i2c *i2c)
	{
	iowrite32(SM0CTL1_STOP \| SM0CTL1_TRI, i2c->base + REG_SM0CTL1_REG);
	return mtk_i2c_wait_idle(i2c);
	}

	static int mtk_i2c_master_cmd(struct mtk_i2c *i2c, u32 cmd, int page_len)
	{
	iowrite32(cmd \| SM0CTL1_TRI \| SM0CTL1_PGLEN(page_len),
	i2c->base + REG_SM0CTL1_REG);
	return mtk_i2c_wait_idle(i2c);
	}

	static int mtk_i2c_master_xfer(struct i2c_adapter adap, struct i2c_msg msgs,
	int num)
	{
	struct mtk_i2c *i2c;
	struct i2c_msg *pmsg;
	u16 addr;
	int i, j, ret, len, page_len;
	u32 cmd;
	u32 data[2];

	i2c = i2c_get_adapdata(adap);

	for (i = 0; i < num; i++) {
	pmsg = &msgs[i];

	/* wait hardware idle */
	ret = mtk_i2c_wait_idle(i2c);
	if (ret)
	goto err_timeout;

	/* start sequence */
	ret = mtk_i2c_master_start(i2c);
	if (ret)
	goto err_timeout;

	/* write address */
	if (pmsg->flags & I2C_M_TEN) {
	/* 10 bits address */
	addr = 0xf0 \| ((pmsg->addr >> 7) & 0x06);
	addr \|= (pmsg->addr & 0xff) << 8;
	if (pmsg->flags & I2C_M_RD)
	addr \|= 1;
	iowrite32(addr, i2c->base + REG_SM0D0_REG);
	ret = mtk_i2c_master_cmd(i2c, SM0CTL1_WRITE, 2);
	if (ret)
	goto err_timeout;
	} else {
	/* 7 bits address */
	addr = i2c_8bit_addr_from_msg(pmsg);
	iowrite32(addr, i2c->base + REG_SM0D0_REG);
	ret = mtk_i2c_master_cmd(i2c, SM0CTL1_WRITE, 1);
	if (ret)
	goto err_timeout;
	}

	/* check address ACK */
	if (!(pmsg->flags & I2C_M_IGNORE_NAK)) {
	ret = mtk_i2c_check_ack(i2c, BIT(0));
	if (ret)
	goto err_ack;
	}

	/* transfer data */
	for (len = pmsg->len, j = 0; len > 0; len -= 8, j += 8) {
	page_len = (len >= 8) ? 8 : len;

	if (pmsg->flags & I2C_M_RD) {
	cmd = (len > 8) ?
	SM0CTL1_READ : SM0CTL1_READ_LAST;
	} else {
	memcpy(data, &pmsg->buf[j], page_len);
	iowrite32(data[0], i2c->base + REG_SM0D0_REG);
	iowrite32(data[1], i2c->base + REG_SM0D1_REG);
	cmd = SM0CTL1_WRITE;
	}

	ret = mtk_i2c_master_cmd(i2c, cmd, page_len);
	if (ret)
	goto err_timeout;

	if (pmsg->flags & I2C_M_RD) {
	data[0] = ioread32(i2c->base + REG_SM0D0_REG);
	data[1] = ioread32(i2c->base + REG_SM0D1_REG);
	memcpy(&pmsg->buf[j], data, page_len);
	} else {
	if (!(pmsg->flags & I2C_M_IGNORE_NAK)) {
	ret = mtk_i2c_check_ack(i2c,
	(1 << page_len)
	- 1);
	if (ret)
	goto err_ack;
	}
	}
	}
	}

	ret = mtk_i2c_master_stop(i2c);
	if (ret)
	goto err_timeout;

	/* the return value is number of executed messages */
	return i;

	err_ack:
	ret = mtk_i2c_master_stop(i2c);
	if (ret)
	goto err_timeout;
	return -ENXIO;

	err_timeout:
	mtk_i2c_dump_reg(i2c);
	mtk_i2c_reset(i2c);
	return ret;
	}

	static u32 mtk_i2c_func(struct i2c_adapter *a)
	{
	return I2C_FUNC_I2C \| I2C_FUNC_SMBUS_EMUL \| I2C_FUNC_PROTOCOL_MANGLING;
	}

	static const struct i2c_algorithm mtk_i2c_algo = {
	.master_xfer = mtk_i2c_master_xfer,
	.functionality = mtk_i2c_func,
	};

	static const struct of_device_id i2c_mtk_dt_ids[] = {
	{ .compatible = "mediatek,mt7621-i2c" },
	{ /* sentinel */ }
	};

	MODULE_DEVICE_TABLE(of, i2c_mtk_dt_ids);

	static void mtk_i2c_init(struct mtk_i2c *i2c)
	{
	i2c->clk_div = clk_get_rate(i2c->clk) / i2c->bus_freq - 1;
	if (i2c->clk_div < 99)
	i2c->clk_div = 99;
	if (i2c->clk_div > SM0CTL0_CLK_DIV_MAX)
	i2c->clk_div = SM0CTL0_CLK_DIV_MAX;

	mtk_i2c_reset(i2c);
	}

	static int mtk_i2c_probe(struct platform_device *pdev)
	{
	struct resource *res;
	struct mtk_i2c *i2c;
	struct i2c_adapter *adap;
	int ret;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

	i2c = devm_kzalloc(&pdev->dev, sizeof(struct mtk_i2c), GFP_KERNEL);
	if (!i2c)
	return -ENOMEM;

	i2c->base = devm_ioremap_resource(&pdev->dev, res);
	if (IS_ERR(i2c->base))
	return PTR_ERR(i2c->base);

	i2c->clk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(i2c->clk)) {
	dev_err(&pdev->dev, "no clock defined\n");
	return PTR_ERR(i2c->clk);
	}
	ret = clk_prepare_enable(i2c->clk);
	if (ret) {
	dev_err(&pdev->dev, "Unable to enable clock\n");
	return ret;
	}

	i2c->dev = &pdev->dev;

	if (of_property_read_u32(pdev->dev.of_node, "clock-frequency",
	&i2c->bus_freq))
	i2c->bus_freq = 100000;

	if (i2c->bus_freq == 0) {
	dev_warn(i2c->dev, "clock-frequency 0 not supported\n");
	return -EINVAL;
	}

	adap = &i2c->adap;
	adap->owner = THIS_MODULE;
	adap->algo = &mtk_i2c_algo;
	adap->retries = 3;
	adap->dev.parent = &pdev->dev;
	i2c_set_adapdata(adap, i2c);
	adap->dev.of_node = pdev->dev.of_node;
	strlcpy(adap->name, dev_name(&pdev->dev), sizeof(adap->name));

	platform_set_drvdata(pdev, i2c);

	mtk_i2c_init(i2c);

	ret = i2c_add_adapter(adap);
	if (ret < 0)
	return ret;

	dev_info(&pdev->dev, "clock %u kHz\n", i2c->bus_freq / 1000);

	return ret;
	}

	static int mtk_i2c_remove(struct platform_device *pdev)
	{
	struct mtk_i2c *i2c = platform_get_drvdata(pdev);

	clk_disable_unprepare(i2c->clk);
	i2c_del_adapter(&i2c->adap);

	return 0;
	}

	static struct platform_driver mtk_i2c_driver = {
	.probe = mtk_i2c_probe,
	.remove = mtk_i2c_remove,
	.driver = {
	.name = "i2c-mt7621",
	.of_match_table = i2c_mtk_dt_ids,
	},
	};

	module_platform_driver(mtk_i2c_driver);

	MODULE_AUTHOR("Steven Liu");
	MODULE_DESCRIPTION("MT7621 I2C host driver");
	MODULE_LICENSE("GPL v2");
	MODULE_ALIAS("platform:MT7621-I2C");