ramips: update i2c drivers

* add rt_i2c structure to store driver data
* rewrite read/write check function and add i2c error status check.
  so we don't need to wait until time out.
* add 10 bits address support. according to the data sheet i think
  it is possible. but i haven't verify it.
* the most important is start transfer only need once. otherwise
  it cause I2C_STARTERR status.
* add set i2c clock speed register by dts options "clock-frequency".
  not just hard code it.
* add mt7621 i2c driver. i just copy i2c-ralink.c and change register
  names. and the hardware don't support error status. so i remove it.
  but the logic is the same.

Signed-off-by: Michael Lee <igvtee@gmail.com>

1 files changed, 275 insertions, 166 deletions

diff --git a/target/linux/ramips/patches-4.4/0044-i2c-MIPS-adds-ralink-I2C-driver.patch b/target/linux/ramips/patches-4.4/0044-i2c-MIPS-adds-ralink-I2C-driver.patch
index 31854eff4b..21872082dd 100644
--- a/target/linux/ramips/patches-4.4/0044-i2c-MIPS-adds-ralink-I2C-driver.patch
+++ b/target/linux/ramips/patches-4.4/0044-i2c-MIPS-adds-ralink-I2C-driver.patch
@@ -45,12 +45,13 @@ Signed-off-by: John Crispin <blogic@openwrt.org>
 +};
 --- a/drivers/i2c/busses/Kconfig
 +++ b/drivers/i2c/busses/Kconfig
-@@ -806,6 +806,10 @@ config I2C_RK3X
+@@ -806,6 +806,11 @@ config I2C_RK3X
  	  This driver can also be built as a module. If so, the module will
  	  be called i2c-rk3x.
  
 +config I2C_RALINK
 +	tristate "Ralink I2C Controller"
++	depends on RALINK && !SOC_MT7621
 +	select OF_I2C
 +
  config HAVE_S3C2410_I2C
@@ -68,11 +69,12 @@ Signed-off-by: John Crispin <blogic@openwrt.org>
  obj-$(CONFIG_I2C_RK3X)		+= i2c-rk3x.o
 --- /dev/null
 +++ b/drivers/i2c/busses/i2c-ralink.c
-@@ -0,0 +1,327 @@
+@@ -0,0 +1,435 @@
 +/*
 + * drivers/i2c/busses/i2c-ralink.c
 + *
 + * Copyright (C) 2013 Steven Liu <steven_liu@mediatek.com>
++ * Copyright (C) 2016 Michael Lee <igvtee@gmail.com>
 + *
 + * Improve driver for i2cdetect from i2c-tools to detect i2c devices on the bus.
 + * (C) 2014 Sittisak <sittisaks@hotmail.com>
@@ -101,8 +103,7 @@ Signed-off-by: John Crispin <blogic@openwrt.org>
 +#include <linux/i2c.h>
 +#include <linux/io.h>
 +#include <linux/err.h>
-+
-+#include <asm/mach-ralink/ralink_regs.h>
++#include <linux/clk.h>
 +
 +#define REG_CONFIG_REG		0x00
 +#define REG_CLKDIV_REG		0x04
@@ -113,191 +114,250 @@ Signed-off-by: John Crispin <blogic@openwrt.org>
 +#define REG_STATUS_REG		0x18
 +#define REG_STARTXFR_REG	0x1C
 +#define REG_BYTECNT_REG		0x20
-+#define REG_SM0CFG2		0x28
-+#define REG_SM0CTL0		0x40
 +
++/* REG_CONFIG_REG */
++#define I2C_ADDRLEN_OFFSET	5
++#define I2C_DEVADLEN_OFFSET	2
++#define I2C_ADDRLEN_MASK	0x3
++#define I2C_ADDR_DIS		BIT(1)
++#define I2C_DEVADDR_DIS		BIT(0)
++#define I2C_ADDRLEN_8		(7 << I2C_ADDRLEN_OFFSET)
++#define I2C_DEVADLEN_7		(6 << I2C_DEVADLEN_OFFSET)
++#define I2C_CONF_DEFAULT	(I2C_ADDRLEN_8 | I2C_DEVADLEN_7)
++
++/* REG_CLKDIV_REG */
++#define I2C_CLKDIV_MASK		0xffff
++
++/* REG_DEVADDR_REG */
++#define I2C_DEVADDR_MASK	0x7f
++
++/* REG_ADDR_REG */
++#define I2C_ADDR_MASK		0xff
++
++/* REG_STATUS_REG */
 +#define I2C_STARTERR		BIT(4)
 +#define I2C_ACKERR		BIT(3)
 +#define I2C_DATARDY		BIT(2)
 +#define I2C_SDOEMPTY		BIT(1)
 +#define I2C_BUSY		BIT(0)
 +
-+#define I2C_DEVADLEN_7		(6 << 2)
-+#define I2C_ADDRDIS		BIT(1)
++/* REG_STARTXFR_REG */
++#define NOSTOP_CMD		BIT(2)
++#define NODATA_CMD		BIT(1)
++#define READ_CMD		BIT(0)
 +
-+#define CLKDIV_VALUE		200 // clock rate is 40M, 40M / (200*2) = 100k (standard i2c bus rate).
-+//#define CLKDIV_VALUE		50 // clock rate is 40M, 40M / (50*2) = 400k (fast i2c bus rate).
-+
-+#define READ_CMD		0x01
-+#define WRITE_CMD		0x00
-+#define READ_BLOCK              64
-+
-+#define SM0CTL0_OD		BIT(31)
-+#define SM0CTL0_VTRIG		BIT(28)
-+#define SM0CTL0_OUTHI		BIT(6)
-+#define SM0CTL0_STRETCH		BIT(1)
-+#define SM0CTL0_DEFAULT		(SM0CTL0_OD | SM0CTL0_VTRIG | SM0CTL0_OUTHI | SM0CTL0_STRETCH)
++/* REG_BYTECNT_REG */
++#define BYTECNT_MAX		64
++#define SET_BYTECNT(x)		(x - 1)
 +
 +/* timeout waiting for I2C devices to respond (clock streching) */
-+#define RT_I2C_TIMEOUT (msecs_to_jiffies(1000))
-+
-+enum {
-+	I2C_TYPE_RALINK,
-+	I2C_TYPE_MEDIATEK,
++#define TIMEOUT_MS              1000
++#define DELAY_INTERVAL_US       100
++
++struct rt_i2c {
++	void __iomem *base;
++	struct clk *clk;
++	struct device *dev;
++	struct i2c_adapter adap;
++	u32 cur_clk;
++	u32 clk_div;
++	u32 flags;
 +};
 +
-+static void __iomem *membase;
-+static struct i2c_adapter *adapter;
-+static int hw_type;
-+
-+static void rt_i2c_w32(u32 val, unsigned reg)
++static void rt_i2c_w32(struct rt_i2c *i2c, u32 val, unsigned reg)
 +{
-+	iowrite32(val, membase + reg);
++	iowrite32(val, i2c->base + reg);
 +}
 +
-+static u32 rt_i2c_r32(unsigned reg)
++static u32 rt_i2c_r32(struct rt_i2c *i2c, unsigned reg)
 +{
-+	return ioread32(membase + reg);
++	return ioread32(i2c->base + reg);
 +}
 +
-+static inline int rt_i2c_get_ack(void)
++static int poll_down_timeout(void __iomem *addr, u32 mask)
 +{
-+        return (rt_i2c_r32(REG_STATUS_REG) & I2C_ACKERR) ? -EIO : 0;
-+}
-+
-+static inline int rt_i2c_wait_rx_done(void)
-+{
-+	unsigned long timeout;
-+
-+	timeout = jiffies + RT_I2C_TIMEOUT;
++	unsigned long timeout = jiffies + msecs_to_jiffies(TIMEOUT_MS);
 +
 +	do {
-+		if (time_after(jiffies, timeout))
-+			return (-ETIMEDOUT);
++		if (!(readl_relaxed(addr) & mask))
++			return 0;
 +
-+	} while (!(rt_i2c_r32(REG_STATUS_REG) & I2C_DATARDY));
++		usleep_range(DELAY_INTERVAL_US, DELAY_INTERVAL_US + 50);
++	} while (time_before(jiffies, timeout));
 +
-+	return 0;
++	return (readl_relaxed(addr) & mask) ? -EAGAIN : 0;
 +}
 +
-+static inline int rt_i2c_wait_idle(void)
++static int rt_i2c_wait_idle(struct rt_i2c *i2c)
 +{
-+	unsigned long timeout;
++	int ret;
 +
-+	timeout = jiffies + RT_I2C_TIMEOUT;
++	ret = poll_down_timeout(i2c->base + REG_STATUS_REG, I2C_BUSY);
++	if (ret < 0)
++		dev_dbg(i2c->dev, "idle err(%d)\n", ret);
 +
-+	do {
-+		if (time_after(jiffies, timeout)) {
-+			printk("i2c-read line busy\n");
-+			return 1;
-+		}
-+	} while (rt_i2c_r32(REG_STATUS_REG) & I2C_BUSY);
-+
-+	return 0;
++	return ret;
 +}
 +
-+static inline int rt_i2c_wait_tx_done(void)
++static int poll_up_timeout(void __iomem *addr, u32 mask)
 +{
-+	unsigned long timeout;
-+
-+	timeout = jiffies + RT_I2C_TIMEOUT;
++	unsigned long timeout = jiffies + msecs_to_jiffies(TIMEOUT_MS);
++	u32 status;
 +
 +	do {
-+		if (time_after(jiffies, timeout))
-+			return (-ETIMEDOUT);
++		status = readl_relaxed(addr);
 +
-+	} while (!(rt_i2c_r32(REG_STATUS_REG) & I2C_SDOEMPTY));
++		/* check error status */
++		if (status & I2C_STARTERR)
++			return -EAGAIN;
++		else if (status & I2C_ACKERR)
++			return -ENXIO;
++		else if (status & mask)
++			return 0;
 +
-+	return 0;
++		usleep_range(DELAY_INTERVAL_US, DELAY_INTERVAL_US + 50);
++	} while (time_before(jiffies, timeout));
++
++	return -ETIMEDOUT;
 +}
 +
-+static int rt_i2c_handle_msg(struct i2c_adapter *a, struct i2c_msg* msg)
++static int rt_i2c_wait_rx_done(struct rt_i2c *i2c)
 +{
-+	int i = 0, j = 0, pos = 0;
-+	int nblock = msg->len / READ_BLOCK;
-+        int rem = msg->len % READ_BLOCK;
-+	int ret = 0;
-+
-+	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())
-+				return -ETIMEDOUT;
-+			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() < 0)
-+					ret = rt_i2c_wait_rx_done();
-+                                if (rt_i2c_get_ack() < 0)
-+					ret = rt_i2c_get_ack();
-+				msg->buf[pos++] = rt_i2c_r32(REG_DATAIN_REG);
-+			}
-+		}
-+
-+		if (rt_i2c_wait_idle())
-+			return -ETIMEDOUT;
-+		if (rem) {
-+			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() < 0)
-+				ret = rt_i2c_wait_rx_done();
-+                        if (rt_i2c_get_ack() < 0)
-+				ret = rt_i2c_get_ack();
++	int ret;
 +
-+			msg->buf[pos++] = rt_i2c_r32(REG_DATAIN_REG);
-+		}
-+	} else {
-+		if (rt_i2c_wait_idle())
-+			return -ETIMEDOUT;
-+		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);
-+			rt_i2c_w32(WRITE_CMD, REG_STARTXFR_REG);
-+
-+			if (rt_i2c_wait_tx_done() < 0)
-+				ret = rt_i2c_wait_tx_done();
-+                        if (rt_i2c_get_ack() < 0)
-+				ret = rt_i2c_get_ack();
-+		}
-+	}
++	ret = poll_up_timeout(i2c->base + REG_STATUS_REG, I2C_DATARDY);
++	if (ret < 0)
++		dev_dbg(i2c->dev, "rx err(%d)\n", ret);
 +
 +	return ret;
 +}
 +
-+static int rt_i2c_master_xfer(struct i2c_adapter *a, struct i2c_msg *m, int n)
++static int rt_i2c_wait_tx_done(struct rt_i2c *i2c)
 +{
-+	int i = 0;
-+	int ret = 0;
++	int ret;
 +
-+	if (rt_i2c_wait_idle())
-+		return -ETIMEDOUT;
++	ret = poll_up_timeout(i2c->base + REG_STATUS_REG, I2C_SDOEMPTY);
++	if (ret < 0)
++		dev_dbg(i2c->dev, "tx err(%d)\n", ret);
 +
-+	device_reset(a->dev.parent);
++	return ret;
++}
 +
-+	rt_i2c_w32(m->addr, REG_DEVADDR_REG);
-+	rt_i2c_w32(I2C_DEVADLEN_7 | I2C_ADDRDIS, REG_CONFIG_REG);
-+	if (hw_type == I2C_TYPE_RALINK) {
-+		rt_i2c_w32(CLKDIV_VALUE, REG_CLKDIV_REG);
-+	} else {
-+		rt_i2c_w32((CLKDIV_VALUE << 16) | SM0CTL0_DEFAULT, REG_SM0CTL0);
-+		rt_i2c_w32(1, REG_SM0CFG2);
-+	}
++static void rt_i2c_reset(struct rt_i2c *i2c)
++{
++	device_reset(i2c->adap.dev.parent);
++	barrier();
++	rt_i2c_w32(i2c, i2c->clk_div, REG_CLKDIV_REG);
++}
++
++static void rt_i2c_dump_reg(struct rt_i2c *i2c)
++{
++	dev_dbg(i2c->dev, "conf %08x, clkdiv %08x, devaddr %08x, " \
++			"addr %08x, dataout %08x, datain %08x, " \
++			"status %08x, startxfr %08x, bytecnt %08x\n",
++			rt_i2c_r32(i2c, REG_CONFIG_REG),
++			rt_i2c_r32(i2c, REG_CLKDIV_REG),
++			rt_i2c_r32(i2c, REG_DEVADDR_REG),
++			rt_i2c_r32(i2c, REG_ADDR_REG),
++			rt_i2c_r32(i2c, REG_DATAOUT_REG),
++			rt_i2c_r32(i2c, REG_DATAIN_REG),
++			rt_i2c_r32(i2c, REG_STATUS_REG),
++			rt_i2c_r32(i2c, REG_STARTXFR_REG),
++			rt_i2c_r32(i2c, REG_BYTECNT_REG));
++}
 +
-+	for (i = 0; i < n && !ret; i++) {
-+		ret = rt_i2c_handle_msg(a, &m[i]);
++static int rt_i2c_master_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
++		int num)
++{
++	struct rt_i2c *i2c;
++	struct i2c_msg *pmsg;
++	unsigned char addr;
++	int i, j, ret;
++	u32 cmd;
++
++	i2c = i2c_get_adapdata(adap);
++
++	for (i = 0; i < num; i++) {
++		pmsg = &msgs[i];
++		if (i == (num - 1))
++			cmd = 0;
++		else
++			cmd = NOSTOP_CMD;
++
++		dev_dbg(i2c->dev, "addr: 0x%x, len: %d, flags: 0x%x, stop: %d\n",
++				pmsg->addr, pmsg->len, pmsg->flags,
++				(cmd == 0)? 1 : 0);
++
++		/* wait hardware idle */
++		if ((ret = rt_i2c_wait_idle(i2c)))
++			goto err_timeout;
++
++		if (pmsg->flags & I2C_M_TEN) {
++			rt_i2c_w32(i2c, I2C_CONF_DEFAULT, REG_CONFIG_REG);
++			/* 10 bits address */
++			addr = 0x78 | ((pmsg->addr >> 8) & 0x03);
++			rt_i2c_w32(i2c, addr & I2C_DEVADDR_MASK,
++					REG_DEVADDR_REG);
++			rt_i2c_w32(i2c, pmsg->addr & I2C_ADDR_MASK,
++					REG_ADDR_REG);
++		} else {
++			rt_i2c_w32(i2c, I2C_CONF_DEFAULT | I2C_ADDR_DIS,
++					REG_CONFIG_REG);
++			/* 7 bits address */
++			rt_i2c_w32(i2c, pmsg->addr & I2C_DEVADDR_MASK,
++					REG_DEVADDR_REG);
++		}
 +
-+		if (ret < 0) {
-+			return ret;
++		/* buffer length */
++		if (pmsg->len == 0)
++			cmd |= NODATA_CMD;
++		else
++			rt_i2c_w32(i2c, SET_BYTECNT(pmsg->len),
++					REG_BYTECNT_REG);
++
++		j = 0;
++		if (pmsg->flags & I2C_M_RD) {
++			cmd |= READ_CMD;
++			/* start transfer */
++			barrier();
++			rt_i2c_w32(i2c, cmd, REG_STARTXFR_REG);
++			do {
++				/* wait */
++				if ((ret = rt_i2c_wait_rx_done(i2c)))
++					goto err_timeout;
++				/* read data */
++				if (pmsg->len)
++					pmsg->buf[j] = rt_i2c_r32(i2c,
++							REG_DATAIN_REG);
++				j++;
++			} while (j < pmsg->len);
++		} else {
++			do {
++				/* write data */
++				if (pmsg->len)
++					rt_i2c_w32(i2c, pmsg->buf[j],
++							REG_DATAOUT_REG);
++				/* start transfer */
++				if (j == 0) {
++					barrier();
++					rt_i2c_w32(i2c, cmd, REG_STARTXFR_REG);
++				}
++				/* wait */
++				if ((ret = rt_i2c_wait_tx_done(i2c)))
++					goto err_timeout;
++				j++;
++			} while (j < pmsg->len);
 +		}
 +	}
++	/* the return value is number of executed messages */
++	ret = i;
++
++	return ret;
 +
-+	return n;
++err_timeout:
++	rt_i2c_dump_reg(i2c);
++	rt_i2c_reset(i2c);
++	return ret;
 +}
 +
 +static u32 rt_i2c_func(struct i2c_adapter *a)
@@ -311,60 +371,110 @@ Signed-off-by: John Crispin <blogic@openwrt.org>
 +};
 +
 +static const struct of_device_id i2c_rt_dt_ids[] = {
-+	{ .compatible = "ralink,rt2880-i2c", .data = (void *) I2C_TYPE_RALINK },
-+	{ .compatible = "mediatek,mt7628-i2c", .data = (void *) I2C_TYPE_MEDIATEK },
++	{ .compatible = "ralink,rt2880-i2c" },
 +	{ /* sentinel */ }
 +};
 +
 +MODULE_DEVICE_TABLE(of, i2c_rt_dt_ids);
 +
++static struct i2c_adapter_quirks rt_i2c_quirks = {
++        .max_write_len = BYTECNT_MAX,
++        .max_read_len = BYTECNT_MAX,
++};
++
++static int rt_i2c_init(struct rt_i2c *i2c)
++{
++	u32 reg;
++
++	/* i2c_sclk = periph_clk / ((2 * clk_div) + 5) */
++	i2c->clk_div = (clk_get_rate(i2c->clk) - (5 * i2c->cur_clk)) /
++		(2 * i2c->cur_clk);
++	if (i2c->clk_div < 8)
++		i2c->clk_div = 8;
++	if (i2c->clk_div > I2C_CLKDIV_MASK)
++		i2c->clk_div = I2C_CLKDIV_MASK;
++
++	/* check support combinde/repeated start message */
++	rt_i2c_w32(i2c, NOSTOP_CMD, REG_STARTXFR_REG);
++	reg = rt_i2c_r32(i2c, REG_STARTXFR_REG) & NOSTOP_CMD;
++
++	rt_i2c_reset(i2c);
++
++	return reg;
++}
++
 +static int rt_i2c_probe(struct platform_device *pdev)
 +{
-+	struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
++	struct resource *res;
++	struct rt_i2c *i2c;
++	struct i2c_adapter *adap;
 +	const struct of_device_id *match;
-+	int ret;
++	int ret, restart;
 +
 +	match = of_match_device(i2c_rt_dt_ids, &pdev->dev);
-+	hw_type = (int) match->data;
 +
++	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 +	if (!res) {
 +		dev_err(&pdev->dev, "no memory resource found\n");
 +		return -ENODEV;
 +	}
 +
-+	adapter = devm_kzalloc(&pdev->dev, sizeof(struct i2c_adapter), GFP_KERNEL);
-+	if (!adapter) {
++	i2c = devm_kzalloc(&pdev->dev, sizeof(struct rt_i2c), GFP_KERNEL);
++	if (!i2c) {
 +		dev_err(&pdev->dev, "failed to allocate i2c_adapter\n");
 +		return -ENOMEM;
 +	}
 +
-+	membase = devm_ioremap_resource(&pdev->dev, res);
-+	if (IS_ERR(membase))
-+		return PTR_ERR(membase);
-+
-+	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;
-+
-+	ret = i2c_add_numbered_adapter(adapter);
-+	if (ret)
-+		return ret;
++	i2c->base = devm_ioremap_resource(&pdev->dev, res);
++	if (IS_ERR(i2c->base))
++		return PTR_ERR(i2c->base);
 +
-+	platform_set_drvdata(pdev, adapter);
++	i2c->clk = devm_clk_get(&pdev->dev, NULL);
++	if (IS_ERR(i2c->clk)) {
++		dev_err(&pdev->dev, "no clock defined\n");
++		return -ENODEV;
++	}
++	clk_prepare_enable(i2c->clk);
++	i2c->dev = &pdev->dev;
++
++	if (of_property_read_u32(pdev->dev.of_node,
++				"clock-frequency", &i2c->cur_clk))
++		i2c->cur_clk = 100000;
++
++	adap = &i2c->adap;
++	adap->owner = THIS_MODULE;
++	adap->class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
++	adap->algo = &rt_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));
++	adap->quirks = &rt_i2c_quirks;
++
++	platform_set_drvdata(pdev, i2c);
++
++	restart = rt_i2c_init(i2c);
++
++	ret = i2c_add_adapter(adap);
++	if (ret < 0) {
++		dev_err(&pdev->dev, "failed to add adapter\n");
++		clk_disable_unprepare(i2c->clk);
++		return ret;
++	}
 +
-+	dev_info(&pdev->dev, "loaded\n");
++	dev_info(&pdev->dev, "clock %uKHz, re-start %ssupport\n",
++			i2c->cur_clk/1000, restart ? "" : "not ");
 +
-+	return 0;
++	return ret;
 +}
 +
 +static int rt_i2c_remove(struct platform_device *pdev)
 +{
-+	platform_set_drvdata(pdev, NULL);
++	struct rt_i2c *i2c = platform_get_drvdata(pdev);
++
++	i2c_del_adapter(&i2c->adap);
++	clk_disable_unprepare(i2c->clk);
 +
 +	return 0;
 +}
@@ -389,8 +499,7 @@ Signed-off-by: John Crispin <blogic@openwrt.org>
 +{
 +	platform_driver_unregister(&rt_i2c_driver);
 +}
-+
-+module_exit (i2c_rt_exit);
++module_exit(i2c_rt_exit);
 +
 +MODULE_AUTHOR("Steven Liu <steven_liu@mediatek.com>");
 +MODULE_DESCRIPTION("Ralink I2c host driver");