[2/2] i2c: zx2967: add i2c controller driver for ZTE's zx2967 family

Message ID 1495947576-11037-3-git-send-email-shawnguo@kernel.org
State New
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Series
  • Add I2C driver for ZTE ZX2967 family SoCs
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Commit Message

Shawn Guo May 28, 2017, 4:59 a.m.
From: Baoyou Xie <baoyou.xie@linaro.org>


This patch adds i2c controller driver for ZTE's zx2967 family.

Signed-off-by: Baoyou Xie <baoyou.xie@linaro.org>

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>

Reviewed-by: Jun Nie <jun.nie@linaro.org>

Signed-off-by: Shawn Guo <shawnguo@kernel.org>

---
 drivers/i2c/busses/Kconfig      |   9 +
 drivers/i2c/busses/Makefile     |   1 +
 drivers/i2c/busses/i2c-zx2967.c | 610 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 620 insertions(+)
 create mode 100644 drivers/i2c/busses/i2c-zx2967.c

-- 
1.9.1

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Comments

Wolfram Sang June 19, 2017, 7:31 p.m. | #1
Hi Shawn,

On Sun, May 28, 2017 at 12:59:36PM +0800, Shawn Guo wrote:
> From: Baoyou Xie <baoyou.xie@linaro.org>

> 

> This patch adds i2c controller driver for ZTE's zx2967 family.

> 

> Signed-off-by: Baoyou Xie <baoyou.xie@linaro.org>

> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>

> Reviewed-by: Jun Nie <jun.nie@linaro.org>

> Signed-off-by: Shawn Guo <shawnguo@kernel.org>


What about this patch from the old series updating the MAINTAINERS entry?
I think it is a good idea?

http://patchwork.ozlabs.org/patch/731006/

> ---

>  drivers/i2c/busses/Kconfig      |   9 +

>  drivers/i2c/busses/Makefile     |   1 +

>  drivers/i2c/busses/i2c-zx2967.c | 610 ++++++++++++++++++++++++++++++++++++++++

>  3 files changed, 620 insertions(+)

>  create mode 100644 drivers/i2c/busses/i2c-zx2967.c

> 

> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig

> index 144cbadc7c72..f9f0ed61df2e 100644

> --- a/drivers/i2c/busses/Kconfig

> +++ b/drivers/i2c/busses/Kconfig

> @@ -1258,4 +1258,13 @@ config I2C_OPAL

>  	  This driver can also be built as a module. If so, the module will be

>  	  called as i2c-opal.

>  

> +config I2C_ZX2967

> +	tristate "ZTE ZX2967 I2C support"

> +	depends on ARCH_ZX


|| COMPILE_TEST?

> +	default y

> +	help

> +	  Selecting this option will add ZX2967 I2C driver.

> +	  This driver can also be built as a module. If so, the module will be

> +	  called i2c-zx2967.

> +

>  endmenu


...

> +static int zx2967_i2c_reset_hardware(struct zx2967_i2c_info *zx_i2c)

> +{

> +	u32 val;

> +	u32 clk_div;

> +	u32 status;

> +

> +	val = I2C_MASTER | I2C_IRQ_MSK_ENABLE;

> +	zx2967_i2c_writel(zx_i2c, val, REG_CMD);

> +

> +	clk_div = clk_get_rate(zx_i2c->clk) / zx_i2c->clk_freq - 1;

> +	zx2967_i2c_writel(zx_i2c, clk_div, REG_CLK_DIV_FS);

> +	zx2967_i2c_writel(zx_i2c, clk_div, REG_CLK_DIV_HS);

> +

> +	zx2967_i2c_writel(zx_i2c, I2C_FIFO_MAX - 1, REG_WRCONF);

> +	zx2967_i2c_writel(zx_i2c, I2C_FIFO_MAX - 1, REG_RDCONF);

> +	zx2967_i2c_writel(zx_i2c, 1, REG_RDCONF);

> +

> +	zx2967_i2c_flush_fifos(zx_i2c);

> +

> +	status = zx2967_i2c_readl(zx_i2c, REG_STAT);

> +	if (status & I2C_SR_BUSY)

> +		return -EBUSY;

> +	if (status & (I2C_SR_EDEVICE | I2C_SR_EDATA))

> +		return -EIO;


Is this the error handling (NACK, etc)? Then, it got lost now since we
don't reset the hardware anymore after timeouts. But that would have
meant that errors are only detected after the timeout was reached
instead of instantly? If so, no good design. But maybe I misunderstand.

> +

> +	enable_irq(zx_i2c->irq);

> +

> +	return 0;

> +}

> +

> +static void zx2967_i2c_isr_clr(struct zx2967_i2c_info *zx_i2c)

> +{

> +	u32 status;

> +

> +	status = zx2967_i2c_readl(zx_i2c, REG_STAT);

> +	status |= I2C_IRQ_ACK_CLEAR;

> +	zx2967_i2c_writel(zx_i2c, status, REG_STAT);

> +}

> +

> +static irqreturn_t zx2967_i2c_isr(int irq, void *dev_id)

> +{

> +	u32 status;

> +	struct zx2967_i2c_info *zx_i2c = (struct zx2967_i2c_info *)dev_id;

> +

> +	status = zx2967_i2c_readl(zx_i2c, REG_STAT) & I2C_INT_MASK;

> +	zx2967_i2c_isr_clr(zx_i2c);

> +

> +	if (status & I2C_ERROR_MASK)

> +		return IRQ_HANDLED;


I would have expected the error handling here.

> +

> +	if (status & I2C_TRANS_DONE)

> +		complete(&zx_i2c->complete);

> +

> +	return IRQ_HANDLED;

> +}


...

> +static int zx2967_smbus_xfer_read(struct zx2967_i2c_info *zx_i2c, int size,

> +				  union i2c_smbus_data *data)

> +{

> +	unsigned long time_left;

> +	u8 buf[2];

> +	u32 val;

> +

> +	reinit_completion(&zx_i2c->complete);

> +

> +	val = zx2967_i2c_readl(zx_i2c, REG_CMD);

> +	val |= I2C_CMB_RW_EN;

> +	zx2967_i2c_writel(zx_i2c, val, REG_CMD);

> +

> +	val = zx2967_i2c_readl(zx_i2c, REG_CMD);

> +	val |= I2C_START;

> +	zx2967_i2c_writel(zx_i2c, val, REG_CMD);

> +

> +	time_left = wait_for_completion_timeout(&zx_i2c->complete,

> +						I2C_TIMEOUT);

> +	if (time_left == 0)

> +		return -ETIMEDOUT;

> +

> +	switch (size) {

> +	case I2C_SMBUS_BYTE:

> +	case I2C_SMBUS_BYTE_DATA:

> +		val = zx2967_i2c_readl(zx_i2c, REG_DATA);

> +		data->byte = val;

> +		break;

> +	case I2C_SMBUS_WORD_DATA:

> +	case I2C_SMBUS_PROC_CALL:

> +		buf[0] = zx2967_i2c_readl(zx_i2c, REG_DATA);

> +		buf[1] = zx2967_i2c_readl(zx_i2c, REG_DATA);

> +		data->word = (buf[0] << 8) | buf[1];

> +		break;

> +	default:

> +		dev_warn(DEV(zx_i2c), "Unsupported transaction %d\n", size);


I wouldn't print something here. If an unsupported SMBus transfer is
used, your driver will fall back to emulate them via I2C. No need to
print a warning then.

> +		return -EOPNOTSUPP;

> +	}

> +

> +	return 0;

> +}

> +

> +#define ZX2967_I2C_FUNCS (I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |	\

> +		I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA |	\

> +		I2C_FUNC_SMBUS_BLOCK_DATA | I2C_FUNC_SMBUS_PROC_CALL |	\

> +		I2C_FUNC_I2C | I2C_FUNC_SMBUS_I2C_BLOCK)

> +

> +static u32 zx2967_i2c_func(struct i2c_adapter *adap)

> +{

> +	return ZX2967_I2C_FUNCS;

> +}


No strong opinion but I think we can return that value directly without
a define.

...

> +	ret = i2c_add_numbered_adapter(&zx_i2c->adap);

> +	if (ret) {

> +		dev_err(&pdev->dev, "failed to add zx2967 i2c adapter\n");


Drop the message, the core will do the reporting.

> +		goto err_clk_unprepare;

> +	}


How was this driver tested BTW?

Regards,

   Wolfram
Shawn Guo June 20, 2017, 2:58 a.m. | #2
Hi Wolfram,

Thanks for taking time help review.

On Mon, Jun 19, 2017 at 09:31:30PM +0200, Wolfram Sang wrote:
> Hi Shawn,

> 

> On Sun, May 28, 2017 at 12:59:36PM +0800, Shawn Guo wrote:

> > From: Baoyou Xie <baoyou.xie@linaro.org>

> > 

> > This patch adds i2c controller driver for ZTE's zx2967 family.

> > 

> > Signed-off-by: Baoyou Xie <baoyou.xie@linaro.org>

> > Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>

> > Reviewed-by: Jun Nie <jun.nie@linaro.org>

> > Signed-off-by: Shawn Guo <shawnguo@kernel.org>

> 

> What about this patch from the old series updating the MAINTAINERS entry?

> I think it is a good idea?

> 

> http://patchwork.ozlabs.org/patch/731006/


Oh, yes, I should have mentioned it in the cover-letter.  Instead of
changing MAINTAINERS file in different subsystem patch series, which may
introduce merge conflicts, we plan to update it with a separate patch
adding all driver entries that lands on mainline, and get it in through
arm-soc tree.  Are you okay with that?

> 

> > ---

> >  drivers/i2c/busses/Kconfig      |   9 +

> >  drivers/i2c/busses/Makefile     |   1 +

> >  drivers/i2c/busses/i2c-zx2967.c | 610 ++++++++++++++++++++++++++++++++++++++++

> >  3 files changed, 620 insertions(+)

> >  create mode 100644 drivers/i2c/busses/i2c-zx2967.c

> > 

> > diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig

> > index 144cbadc7c72..f9f0ed61df2e 100644

> > --- a/drivers/i2c/busses/Kconfig

> > +++ b/drivers/i2c/busses/Kconfig

> > @@ -1258,4 +1258,13 @@ config I2C_OPAL

> >  	  This driver can also be built as a module. If so, the module will be

> >  	  called as i2c-opal.

> >  

> > +config I2C_ZX2967

> > +	tristate "ZTE ZX2967 I2C support"

> > +	depends on ARCH_ZX

> 

> || COMPILE_TEST?


Yeah, good suggestion.

> 

> > +	default y

> > +	help

> > +	  Selecting this option will add ZX2967 I2C driver.

> > +	  This driver can also be built as a module. If so, the module will be

> > +	  called i2c-zx2967.

> > +

> >  endmenu

> 

> ...

> 

> > +static int zx2967_i2c_reset_hardware(struct zx2967_i2c_info *zx_i2c)

> > +{

> > +	u32 val;

> > +	u32 clk_div;

> > +	u32 status;

> > +

> > +	val = I2C_MASTER | I2C_IRQ_MSK_ENABLE;

> > +	zx2967_i2c_writel(zx_i2c, val, REG_CMD);

> > +

> > +	clk_div = clk_get_rate(zx_i2c->clk) / zx_i2c->clk_freq - 1;

> > +	zx2967_i2c_writel(zx_i2c, clk_div, REG_CLK_DIV_FS);

> > +	zx2967_i2c_writel(zx_i2c, clk_div, REG_CLK_DIV_HS);

> > +

> > +	zx2967_i2c_writel(zx_i2c, I2C_FIFO_MAX - 1, REG_WRCONF);

> > +	zx2967_i2c_writel(zx_i2c, I2C_FIFO_MAX - 1, REG_RDCONF);

> > +	zx2967_i2c_writel(zx_i2c, 1, REG_RDCONF);

> > +

> > +	zx2967_i2c_flush_fifos(zx_i2c);

> > +

> > +	status = zx2967_i2c_readl(zx_i2c, REG_STAT);

> > +	if (status & I2C_SR_BUSY)

> > +		return -EBUSY;

> > +	if (status & (I2C_SR_EDEVICE | I2C_SR_EDATA))

> > +		return -EIO;

> 

> Is this the error handling (NACK, etc)? Then, it got lost now since we

> don't reset the hardware anymore after timeouts. But that would have

> meant that errors are only detected after the timeout was reached

> instead of instantly? If so, no good design. But maybe I misunderstand.


Hmm, this doesn't make too much sense now, since this reset function is
only being called at probe time to ensure the device is in a sane
initial state.  There is no data transfer happening at this point at
all.  I will drop these error bits checking from here, and add the error
handling in irq handler.

> 

> > +

> > +	enable_irq(zx_i2c->irq);

> > +

> > +	return 0;

> > +}

> > +

> > +static void zx2967_i2c_isr_clr(struct zx2967_i2c_info *zx_i2c)

> > +{

> > +	u32 status;

> > +

> > +	status = zx2967_i2c_readl(zx_i2c, REG_STAT);

> > +	status |= I2C_IRQ_ACK_CLEAR;

> > +	zx2967_i2c_writel(zx_i2c, status, REG_STAT);

> > +}

> > +

> > +static irqreturn_t zx2967_i2c_isr(int irq, void *dev_id)

> > +{

> > +	u32 status;

> > +	struct zx2967_i2c_info *zx_i2c = (struct zx2967_i2c_info *)dev_id;

> > +

> > +	status = zx2967_i2c_readl(zx_i2c, REG_STAT) & I2C_INT_MASK;

> > +	zx2967_i2c_isr_clr(zx_i2c);

> > +

> > +	if (status & I2C_ERROR_MASK)

> > +		return IRQ_HANDLED;

> 

> I would have expected the error handling here.


Yes, we should check error status here.

> 

> > +

> > +	if (status & I2C_TRANS_DONE)

> > +		complete(&zx_i2c->complete);

> > +

> > +	return IRQ_HANDLED;

> > +}

> 

> ...

> 

> > +static int zx2967_smbus_xfer_read(struct zx2967_i2c_info *zx_i2c, int size,

> > +				  union i2c_smbus_data *data)

> > +{

> > +	unsigned long time_left;

> > +	u8 buf[2];

> > +	u32 val;

> > +

> > +	reinit_completion(&zx_i2c->complete);

> > +

> > +	val = zx2967_i2c_readl(zx_i2c, REG_CMD);

> > +	val |= I2C_CMB_RW_EN;

> > +	zx2967_i2c_writel(zx_i2c, val, REG_CMD);

> > +

> > +	val = zx2967_i2c_readl(zx_i2c, REG_CMD);

> > +	val |= I2C_START;

> > +	zx2967_i2c_writel(zx_i2c, val, REG_CMD);

> > +

> > +	time_left = wait_for_completion_timeout(&zx_i2c->complete,

> > +						I2C_TIMEOUT);

> > +	if (time_left == 0)

> > +		return -ETIMEDOUT;

> > +

> > +	switch (size) {

> > +	case I2C_SMBUS_BYTE:

> > +	case I2C_SMBUS_BYTE_DATA:

> > +		val = zx2967_i2c_readl(zx_i2c, REG_DATA);

> > +		data->byte = val;

> > +		break;

> > +	case I2C_SMBUS_WORD_DATA:

> > +	case I2C_SMBUS_PROC_CALL:

> > +		buf[0] = zx2967_i2c_readl(zx_i2c, REG_DATA);

> > +		buf[1] = zx2967_i2c_readl(zx_i2c, REG_DATA);

> > +		data->word = (buf[0] << 8) | buf[1];

> > +		break;

> > +	default:

> > +		dev_warn(DEV(zx_i2c), "Unsupported transaction %d\n", size);

> 

> I wouldn't print something here. If an unsupported SMBus transfer is

> used, your driver will fall back to emulate them via I2C. No need to

> print a warning then.


Okay, will drop it.

> 

> > +		return -EOPNOTSUPP;

> > +	}

> > +

> > +	return 0;

> > +}

> > +

> > +#define ZX2967_I2C_FUNCS (I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |	\

> > +		I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA |	\

> > +		I2C_FUNC_SMBUS_BLOCK_DATA | I2C_FUNC_SMBUS_PROC_CALL |	\

> > +		I2C_FUNC_I2C | I2C_FUNC_SMBUS_I2C_BLOCK)

> > +

> > +static u32 zx2967_i2c_func(struct i2c_adapter *adap)

> > +{

> > +	return ZX2967_I2C_FUNCS;

> > +}

> 

> No strong opinion but I think we can return that value directly without

> a define.


I do not have a strong opinion either, but since you ask, I will do what
you are asking here.

> 

> ...

> 

> > +	ret = i2c_add_numbered_adapter(&zx_i2c->adap);

> > +	if (ret) {

> > +		dev_err(&pdev->dev, "failed to add zx2967 i2c adapter\n");

> 

> Drop the message, the core will do the reporting.


Okay, will do.

> 

> > +		goto err_clk_unprepare;

> > +	}

> 

> How was this driver tested BTW?


The driver is being used to access an Audio codec on the I2C bus.

Shawn
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Wolfram Sang June 20, 2017, 7:41 a.m. | #3
Hi Shawn,

> Oh, yes, I should have mentioned it in the cover-letter.  Instead of

> changing MAINTAINERS file in different subsystem patch series, which may

> introduce merge conflicts, we plan to update it with a separate patch

> adding all driver entries that lands on mainline, and get it in through

> arm-soc tree.  Are you okay with that?


Yup, totally fine! Good approach.

> > Is this the error handling (NACK, etc)? Then, it got lost now since we

> > don't reset the hardware anymore after timeouts. But that would have

> > meant that errors are only detected after the timeout was reached

> > instead of instantly? If so, no good design. But maybe I misunderstand.

> 

> Hmm, this doesn't make too much sense now, since this reset function is

> only being called at probe time to ensure the device is in a sane

> initial state.  There is no data transfer happening at this point at

> all.  I will drop these error bits checking from here, and add the error

> handling in irq handler.


Great, thanks!

> > How was this driver tested BTW?

> 

> The driver is being used to access an Audio codec on the I2C bus.


Nice. Can you also run 'i2cdetect' on the bus to see if we have proper
NAK handling? AFAICS this should be broken now. And very slow with
previous versions of the driver.

Thanks,

   Wolfram
Shawn Guo June 21, 2017, 4:06 p.m. | #4
On Tue, Jun 20, 2017 at 09:41:26AM +0200, Wolfram Sang wrote:
> Nice. Can you also run 'i2cdetect' on the bus to see if we have proper

> NAK handling? AFAICS this should be broken now. And very slow with

> previous versions of the driver.


Sure, thanks for the suggestion.  I will make sure that 'i2cdetect' is
happy with the driver.

Shawn
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Shawn Guo June 22, 2017, 7:48 a.m. | #5
On Tue, Jun 20, 2017 at 09:41:26AM +0200, Wolfram Sang wrote:
> > > How was this driver tested BTW?

> > 

> > The driver is being used to access an Audio codec on the I2C bus.

> 

> Nice. Can you also run 'i2cdetect' on the bus to see if we have proper

> NAK handling? AFAICS this should be broken now. And very slow with

> previous versions of the driver.


Hmm, it seems that 'i2cdetect' works fine with the driver.

$ i2cdetect -l
i2c-0   i2c             zx2967 i2c adapter                      I2C adapter
$ i2cdetect 0
WARNING! This program can confuse your I2C bus, cause data loss and worse!
I will probe file /dev/i2c-0.
I will probe address range 0x03-0x77.
Continue? [Y/n] Y
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- UU -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- 44 -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- 5a -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: 70 -- -- -- -- -- -- --                         
$

The audio codec is on address 0x22.

Why do you think it should be broken now?

Shawn
Wolfram Sang June 22, 2017, 8:07 a.m. | #6
> The audio codec is on address 0x22.

> 

> Why do you think it should be broken now?


Because I thought that we skipped the error handling for every transfer
when we removed the call to reset_hardware from the xfer function.

So, either it still works because the transfer times out. But then
i2cdetect should be really slow. The timeout is set to 1s, so it should
take 1s to scan every address.

Or I am completely missing something. Then, I am sorry for the noise.

Thanks for testing anyhow!
Shawn Guo June 22, 2017, 12:25 p.m. | #7
On Thu, Jun 22, 2017 at 10:07:30AM +0200, Wolfram Sang wrote:
> 

> > The audio codec is on address 0x22.

> > 

> > Why do you think it should be broken now?

> 

> Because I thought that we skipped the error handling for every transfer

> when we removed the call to reset_hardware from the xfer function.

> 

> So, either it still works because the transfer times out. But then

> i2cdetect should be really slow. The timeout is set to 1s, so it should

> take 1s to scan every address.

> 

> Or I am completely missing something. Then, I am sorry for the noise.


It's me who is missing something.  You are right.  With the current
driver, i2cdetect takes 1s to scan most addresses.  Except address 0x22,
those devices detected on other addresses are just wrong, and the
addresses vary from a scan to another.

With the proper error handling, i2cdetect now works very fast and only
gets audio codec on 0x22, which is correct.

$ i2cdetect 0
WARNING! This program can confuse your I2C bus, cause data loss and worse!
I will probe file /dev/i2c-0.
I will probe address range 0x03-0x77.
Continue? [Y/n] Y
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- UU -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --                         

Thanks a lot for identifying the bug.

Shawn
Wolfram Sang June 22, 2017, 1:22 p.m. | #8
> With the proper error handling, i2cdetect now works very fast and only

> gets audio codec on 0x22, which is correct.


Cool! Now make sure that the error codes are matching
Documentation/i2c/fault-codes and I think we are ready to go.

> Thanks a lot for identifying the bug.


You are welcome!

Patch

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 144cbadc7c72..f9f0ed61df2e 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -1258,4 +1258,13 @@  config I2C_OPAL
 	  This driver can also be built as a module. If so, the module will be
 	  called as i2c-opal.
 
+config I2C_ZX2967
+	tristate "ZTE ZX2967 I2C support"
+	depends on ARCH_ZX
+	default y
+	help
+	  Selecting this option will add ZX2967 I2C driver.
+	  This driver can also be built as a module. If so, the module will be
+	  called i2c-zx2967.
+
 endmenu
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 30b60855fbcd..6ece77785a29 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -102,6 +102,7 @@  obj-$(CONFIG_I2C_XILINX)	+= i2c-xiic.o
 obj-$(CONFIG_I2C_XLR)		+= i2c-xlr.o
 obj-$(CONFIG_I2C_XLP9XX)	+= i2c-xlp9xx.o
 obj-$(CONFIG_I2C_RCAR)		+= i2c-rcar.o
+obj-$(CONFIG_I2C_ZX2967)	+= i2c-zx2967.o
 
 # External I2C/SMBus adapter drivers
 obj-$(CONFIG_I2C_DIOLAN_U2C)	+= i2c-diolan-u2c.o
diff --git a/drivers/i2c/busses/i2c-zx2967.c b/drivers/i2c/busses/i2c-zx2967.c
new file mode 100644
index 000000000000..d7f397ab90f1
--- /dev/null
+++ b/drivers/i2c/busses/i2c-zx2967.c
@@ -0,0 +1,610 @@ 
+/*
+ * Copyright (C) 2017 Sanechips Technology Co., Ltd.
+ * Copyright 2017 Linaro Ltd.
+ *
+ * Author: Baoyou Xie <baoyou.xie@linaro.org>
+ *
+ * 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.
+ */
+
+#include <linux/clk.h>
+#include <linux/i2c.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+
+#define REG_CMD				0x04
+#define REG_DEVADDR_H			0x0C
+#define REG_DEVADDR_L			0x10
+#define REG_CLK_DIV_FS			0x14
+#define REG_CLK_DIV_HS			0x18
+#define REG_WRCONF			0x1C
+#define REG_RDCONF			0x20
+#define REG_DATA			0x24
+#define REG_STAT			0x28
+
+#define I2C_STOP			0
+#define I2C_MASTER			BIT(0)
+#define I2C_ADDR_MODE_TEN		BIT(1)
+#define I2C_IRQ_MSK_ENABLE		BIT(3)
+#define I2C_RW_READ			BIT(4)
+#define I2C_CMB_RW_EN			BIT(5)
+#define I2C_START			BIT(6)
+
+#define I2C_ADDR_LOW_MASK		GENMASK(6, 0)
+#define I2C_ADDR_LOW_SHIFT		0
+#define I2C_ADDR_HI_MASK		GENMASK(2, 0)
+#define I2C_ADDR_HI_SHIFT		7
+
+#define I2C_WFIFO_RESET			BIT(7)
+#define I2C_RFIFO_RESET			BIT(7)
+
+#define I2C_IRQ_ACK_CLEAR		BIT(7)
+#define I2C_INT_MASK			GENMASK(6, 0)
+
+#define I2C_TRANS_DONE			BIT(0)
+#define I2C_ERROR_DEVICE		BIT(1)
+#define I2C_ERROR_DATA			BIT(2)
+#define I2C_ERROR_MASK			GENMASK(2, 1)
+
+#define I2C_SR_BUSY			BIT(6)
+
+#define I2C_SR_EDEVICE			BIT(1)
+#define I2C_SR_EDATA			BIT(2)
+
+#define I2C_FIFO_MAX			16
+
+#define I2C_TIMEOUT			msecs_to_jiffies(1000)
+
+#define DEV(i2c)			(&i2c->adap.dev)
+
+struct zx2967_i2c_info {
+	struct i2c_adapter	adap;
+	struct clk		*clk;
+	struct completion	complete;
+	u32			clk_freq;
+	void __iomem		*reg_base;
+	size_t			residue;
+	int			irq;
+	int			msg_rd;
+	u8			*cur_trans;
+	u8			access_cnt;
+	bool			is_suspended;
+};
+
+static void zx2967_i2c_writel(struct zx2967_i2c_info *zx_i2c,
+			      u32 val, unsigned long reg)
+{
+	writel_relaxed(val, zx_i2c->reg_base + reg);
+}
+
+static u32 zx2967_i2c_readl(struct zx2967_i2c_info *zx_i2c, unsigned long reg)
+{
+	return readl_relaxed(zx_i2c->reg_base + reg);
+}
+
+static void zx2967_i2c_writesb(struct zx2967_i2c_info *zx_i2c,
+			       void *data, unsigned long reg, int len)
+{
+	writesb(zx_i2c->reg_base + reg, data, len);
+}
+
+static void zx2967_i2c_readsb(struct zx2967_i2c_info *zx_i2c,
+			      void *data, unsigned long reg, int len)
+{
+	readsb(zx_i2c->reg_base + reg, data, len);
+}
+
+static void zx2967_i2c_start_ctrl(struct zx2967_i2c_info *zx_i2c)
+{
+	u32 status;
+	u32 ctl;
+
+	status = zx2967_i2c_readl(zx_i2c, REG_STAT);
+	status |= I2C_IRQ_ACK_CLEAR;
+	zx2967_i2c_writel(zx_i2c, status, REG_STAT);
+
+	ctl = zx2967_i2c_readl(zx_i2c, REG_CMD);
+	if (zx_i2c->msg_rd)
+		ctl |= I2C_RW_READ;
+	else
+		ctl &= ~I2C_RW_READ;
+	ctl &= ~I2C_CMB_RW_EN;
+	ctl |= I2C_START;
+	zx2967_i2c_writel(zx_i2c, ctl, REG_CMD);
+}
+
+static void zx2967_i2c_flush_fifos(struct zx2967_i2c_info *zx_i2c)
+{
+	u32 offset;
+	u32 val;
+
+	if (zx_i2c->msg_rd) {
+		offset = REG_RDCONF;
+		val = I2C_RFIFO_RESET;
+	} else {
+		offset = REG_WRCONF;
+		val = I2C_WFIFO_RESET;
+	}
+
+	val |= zx2967_i2c_readl(zx_i2c, offset);
+	zx2967_i2c_writel(zx_i2c, val, offset);
+}
+
+static int zx2967_i2c_empty_rx_fifo(struct zx2967_i2c_info *zx_i2c, u32 size)
+{
+	u8 val[I2C_FIFO_MAX] = {0};
+	int i;
+
+	if (size > I2C_FIFO_MAX) {
+		dev_err(DEV(zx_i2c), "fifo size %d over the max value %d\n",
+			size, I2C_FIFO_MAX);
+		return -EINVAL;
+	}
+
+	zx2967_i2c_readsb(zx_i2c, val, REG_DATA, size);
+	for (i = 0; i < size; i++) {
+		*zx_i2c->cur_trans++ = val[i];
+		zx_i2c->residue--;
+	}
+
+	barrier();
+
+	return 0;
+}
+
+static int zx2967_i2c_fill_tx_fifo(struct zx2967_i2c_info *zx_i2c)
+{
+	size_t residue = zx_i2c->residue;
+	u8 *buf = zx_i2c->cur_trans;
+
+	if (residue == 0) {
+		dev_err(DEV(zx_i2c), "residue is %d\n", (int)residue);
+		return -EINVAL;
+	}
+
+	if (residue <= I2C_FIFO_MAX) {
+		zx2967_i2c_writesb(zx_i2c, buf, REG_DATA, residue);
+
+		/* Again update before writing to FIFO to make sure isr sees. */
+		zx_i2c->residue = 0;
+		zx_i2c->cur_trans = NULL;
+	} else {
+		zx2967_i2c_writesb(zx_i2c, buf, REG_DATA, I2C_FIFO_MAX);
+		zx_i2c->residue -= I2C_FIFO_MAX;
+		zx_i2c->cur_trans += I2C_FIFO_MAX;
+	}
+
+	barrier();
+
+	return 0;
+}
+
+static int zx2967_i2c_reset_hardware(struct zx2967_i2c_info *zx_i2c)
+{
+	u32 val;
+	u32 clk_div;
+	u32 status;
+
+	val = I2C_MASTER | I2C_IRQ_MSK_ENABLE;
+	zx2967_i2c_writel(zx_i2c, val, REG_CMD);
+
+	clk_div = clk_get_rate(zx_i2c->clk) / zx_i2c->clk_freq - 1;
+	zx2967_i2c_writel(zx_i2c, clk_div, REG_CLK_DIV_FS);
+	zx2967_i2c_writel(zx_i2c, clk_div, REG_CLK_DIV_HS);
+
+	zx2967_i2c_writel(zx_i2c, I2C_FIFO_MAX - 1, REG_WRCONF);
+	zx2967_i2c_writel(zx_i2c, I2C_FIFO_MAX - 1, REG_RDCONF);
+	zx2967_i2c_writel(zx_i2c, 1, REG_RDCONF);
+
+	zx2967_i2c_flush_fifos(zx_i2c);
+
+	status = zx2967_i2c_readl(zx_i2c, REG_STAT);
+	if (status & I2C_SR_BUSY)
+		return -EBUSY;
+	if (status & (I2C_SR_EDEVICE | I2C_SR_EDATA))
+		return -EIO;
+
+	enable_irq(zx_i2c->irq);
+
+	return 0;
+}
+
+static void zx2967_i2c_isr_clr(struct zx2967_i2c_info *zx_i2c)
+{
+	u32 status;
+
+	status = zx2967_i2c_readl(zx_i2c, REG_STAT);
+	status |= I2C_IRQ_ACK_CLEAR;
+	zx2967_i2c_writel(zx_i2c, status, REG_STAT);
+}
+
+static irqreturn_t zx2967_i2c_isr(int irq, void *dev_id)
+{
+	u32 status;
+	struct zx2967_i2c_info *zx_i2c = (struct zx2967_i2c_info *)dev_id;
+
+	status = zx2967_i2c_readl(zx_i2c, REG_STAT) & I2C_INT_MASK;
+	zx2967_i2c_isr_clr(zx_i2c);
+
+	if (status & I2C_ERROR_MASK)
+		return IRQ_HANDLED;
+
+	if (status & I2C_TRANS_DONE)
+		complete(&zx_i2c->complete);
+
+	return IRQ_HANDLED;
+}
+
+static void zx2967_set_addr(struct zx2967_i2c_info *zx_i2c, u16 addr)
+{
+	u16 val;
+
+	val = (addr >> I2C_ADDR_LOW_SHIFT) & I2C_ADDR_LOW_MASK;
+	zx2967_i2c_writel(zx_i2c, val, REG_DEVADDR_L);
+
+	val = (addr >> I2C_ADDR_HI_SHIFT) & I2C_ADDR_HI_MASK;
+	zx2967_i2c_writel(zx_i2c, val, REG_DEVADDR_H);
+	if (val)
+		val = zx2967_i2c_readl(zx_i2c, REG_CMD) | I2C_ADDR_MODE_TEN;
+	else
+		val = zx2967_i2c_readl(zx_i2c, REG_CMD) & ~I2C_ADDR_MODE_TEN;
+	zx2967_i2c_writel(zx_i2c, val, REG_CMD);
+}
+
+static int zx2967_i2c_xfer_bytes(struct zx2967_i2c_info *zx_i2c, u32 bytes)
+{
+	unsigned long time_left;
+	int rd = zx_i2c->msg_rd;
+	int ret;
+
+	reinit_completion(&zx_i2c->complete);
+
+	if (rd) {
+		zx2967_i2c_writel(zx_i2c, bytes - 1, REG_RDCONF);
+	} else {
+		ret = zx2967_i2c_fill_tx_fifo(zx_i2c);
+		if (ret)
+			return ret;
+	}
+
+	zx2967_i2c_start_ctrl(zx_i2c);
+
+	time_left = wait_for_completion_timeout(&zx_i2c->complete,
+						I2C_TIMEOUT);
+	if (time_left == 0)
+		return -ETIMEDOUT;
+
+	return rd ? zx2967_i2c_empty_rx_fifo(zx_i2c, bytes) : 0;
+}
+
+static int zx2967_i2c_xfer_msg(struct zx2967_i2c_info *zx_i2c,
+			       struct i2c_msg *msg)
+{
+	int ret;
+	int i;
+
+	if (msg->len == 0)
+		return -EINVAL;
+
+	zx2967_i2c_flush_fifos(zx_i2c);
+
+	zx_i2c->cur_trans = msg->buf;
+	zx_i2c->residue = msg->len;
+	zx_i2c->access_cnt = msg->len / I2C_FIFO_MAX;
+	zx_i2c->msg_rd = msg->flags & I2C_M_RD;
+
+	for (i = 0; i < zx_i2c->access_cnt; i++) {
+		ret = zx2967_i2c_xfer_bytes(zx_i2c, I2C_FIFO_MAX);
+		if (ret)
+			return ret;
+	}
+
+	if (zx_i2c->residue > 0) {
+		ret = zx2967_i2c_xfer_bytes(zx_i2c, zx_i2c->residue);
+		if (ret)
+			return ret;
+	}
+
+	zx_i2c->residue = 0;
+	zx_i2c->access_cnt = 0;
+
+	return 0;
+}
+
+static int zx2967_i2c_xfer(struct i2c_adapter *adap,
+			   struct i2c_msg *msgs, int num)
+{
+	struct zx2967_i2c_info *zx_i2c = i2c_get_adapdata(adap);
+	int ret;
+	int i;
+
+	if (zx_i2c->is_suspended)
+		return -EBUSY;
+
+	zx2967_set_addr(zx_i2c, msgs->addr);
+
+	for (i = 0; i < num; i++) {
+		ret = zx2967_i2c_xfer_msg(zx_i2c, &msgs[i]);
+		if (ret)
+			return ret;
+	}
+
+	return num;
+}
+
+static void
+zx2967_smbus_xfer_prepare(struct zx2967_i2c_info *zx_i2c, u16 addr,
+			  char read_write, u8 command, int size,
+			  union i2c_smbus_data *data)
+{
+	u32 val;
+
+	val = zx2967_i2c_readl(zx_i2c, REG_RDCONF);
+	val |= I2C_RFIFO_RESET;
+	zx2967_i2c_writel(zx_i2c, val, REG_RDCONF);
+	zx2967_set_addr(zx_i2c, addr);
+	val = zx2967_i2c_readl(zx_i2c, REG_CMD);
+	val &= ~I2C_RW_READ;
+	zx2967_i2c_writel(zx_i2c, val, REG_CMD);
+
+	switch (size) {
+	case I2C_SMBUS_BYTE:
+		zx2967_i2c_writel(zx_i2c, command, REG_DATA);
+		break;
+	case I2C_SMBUS_BYTE_DATA:
+		zx2967_i2c_writel(zx_i2c, command, REG_DATA);
+		if (read_write == I2C_SMBUS_WRITE)
+			zx2967_i2c_writel(zx_i2c, data->byte, REG_DATA);
+		break;
+	case I2C_SMBUS_WORD_DATA:
+		zx2967_i2c_writel(zx_i2c, command, REG_DATA);
+		if (read_write == I2C_SMBUS_WRITE) {
+			zx2967_i2c_writel(zx_i2c, (data->word >> 8), REG_DATA);
+			zx2967_i2c_writel(zx_i2c, (data->word & 0xff),
+					  REG_DATA);
+		}
+		break;
+	}
+}
+
+static int zx2967_smbus_xfer_read(struct zx2967_i2c_info *zx_i2c, int size,
+				  union i2c_smbus_data *data)
+{
+	unsigned long time_left;
+	u8 buf[2];
+	u32 val;
+
+	reinit_completion(&zx_i2c->complete);
+
+	val = zx2967_i2c_readl(zx_i2c, REG_CMD);
+	val |= I2C_CMB_RW_EN;
+	zx2967_i2c_writel(zx_i2c, val, REG_CMD);
+
+	val = zx2967_i2c_readl(zx_i2c, REG_CMD);
+	val |= I2C_START;
+	zx2967_i2c_writel(zx_i2c, val, REG_CMD);
+
+	time_left = wait_for_completion_timeout(&zx_i2c->complete,
+						I2C_TIMEOUT);
+	if (time_left == 0)
+		return -ETIMEDOUT;
+
+	switch (size) {
+	case I2C_SMBUS_BYTE:
+	case I2C_SMBUS_BYTE_DATA:
+		val = zx2967_i2c_readl(zx_i2c, REG_DATA);
+		data->byte = val;
+		break;
+	case I2C_SMBUS_WORD_DATA:
+	case I2C_SMBUS_PROC_CALL:
+		buf[0] = zx2967_i2c_readl(zx_i2c, REG_DATA);
+		buf[1] = zx2967_i2c_readl(zx_i2c, REG_DATA);
+		data->word = (buf[0] << 8) | buf[1];
+		break;
+	default:
+		dev_warn(DEV(zx_i2c), "Unsupported transaction %d\n", size);
+		return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+
+static int zx2967_smbus_xfer_write(struct zx2967_i2c_info *zx_i2c)
+{
+	unsigned long time_left;
+	u32 val;
+
+	reinit_completion(&zx_i2c->complete);
+	val = zx2967_i2c_readl(zx_i2c, REG_CMD);
+	val |= I2C_START;
+	zx2967_i2c_writel(zx_i2c, val, REG_CMD);
+
+	time_left = wait_for_completion_timeout(&zx_i2c->complete,
+						I2C_TIMEOUT);
+	if (time_left == 0)
+		return -ETIMEDOUT;
+
+	return 0;
+}
+
+static int zx2967_smbus_xfer(struct i2c_adapter *adap, u16 addr,
+			     unsigned short flags, char read_write,
+			     u8 command, int size, union i2c_smbus_data *data)
+{
+	struct zx2967_i2c_info *zx_i2c = i2c_get_adapdata(adap);
+
+	if (size == I2C_SMBUS_QUICK)
+		read_write = I2C_SMBUS_WRITE;
+
+	switch (size) {
+	case I2C_SMBUS_QUICK:
+	case I2C_SMBUS_BYTE:
+	case I2C_SMBUS_BYTE_DATA:
+	case I2C_SMBUS_WORD_DATA:
+		zx2967_smbus_xfer_prepare(zx_i2c, addr, read_write,
+					  command, size, data);
+		break;
+	default:
+		dev_warn(&adap->dev, "Unsupported transaction %d\n", size);
+		return -EOPNOTSUPP;
+	}
+
+	if (read_write == I2C_SMBUS_READ)
+		return zx2967_smbus_xfer_read(zx_i2c, size, data);
+
+	return zx2967_smbus_xfer_write(zx_i2c);
+}
+
+#define ZX2967_I2C_FUNCS (I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE |	\
+		I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA |	\
+		I2C_FUNC_SMBUS_BLOCK_DATA | I2C_FUNC_SMBUS_PROC_CALL |	\
+		I2C_FUNC_I2C | I2C_FUNC_SMBUS_I2C_BLOCK)
+
+static u32 zx2967_i2c_func(struct i2c_adapter *adap)
+{
+	return ZX2967_I2C_FUNCS;
+}
+
+static int __maybe_unused zx2967_i2c_suspend(struct device *dev)
+{
+	struct zx2967_i2c_info *zx_i2c = dev_get_drvdata(dev);
+
+	zx_i2c->is_suspended = true;
+	clk_disable_unprepare(zx_i2c->clk);
+
+	return 0;
+}
+
+static int __maybe_unused zx2967_i2c_resume(struct device *dev)
+{
+	struct zx2967_i2c_info *zx_i2c = dev_get_drvdata(dev);
+
+	zx_i2c->is_suspended = false;
+	clk_prepare_enable(zx_i2c->clk);
+
+	return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(zx2967_i2c_dev_pm_ops,
+			 zx2967_i2c_suspend, zx2967_i2c_resume);
+
+static const struct i2c_algorithm zx2967_i2c_algo = {
+	.master_xfer = zx2967_i2c_xfer,
+	.smbus_xfer = zx2967_smbus_xfer,
+	.functionality = zx2967_i2c_func,
+};
+
+static const struct of_device_id zx2967_i2c_of_match[] = {
+	{ .compatible = "zte,zx296718-i2c", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, zx2967_i2c_of_match);
+
+static int zx2967_i2c_probe(struct platform_device *pdev)
+{
+	struct zx2967_i2c_info *zx_i2c;
+	void __iomem *reg_base;
+	struct resource *res;
+	struct clk *clk;
+	int ret;
+
+	zx_i2c = devm_kzalloc(&pdev->dev, sizeof(*zx_i2c), GFP_KERNEL);
+	if (!zx_i2c)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	reg_base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(reg_base))
+		return PTR_ERR(reg_base);
+
+	clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(clk)) {
+		dev_err(&pdev->dev, "missing controller clock");
+		return PTR_ERR(clk);
+	}
+
+	ret = clk_prepare_enable(clk);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to enable i2c_clk\n");
+		return ret;
+	}
+
+	ret = device_property_read_u32(&pdev->dev, "clock-frequency",
+				       &zx_i2c->clk_freq);
+	if (ret) {
+		dev_err(&pdev->dev, "missing clock-frequency");
+		return ret;
+	}
+
+	ret = platform_get_irq(pdev, 0);
+	if (ret < 0)
+		return ret;
+
+	zx_i2c->irq = ret;
+	zx_i2c->reg_base = reg_base;
+	zx_i2c->clk = clk;
+
+	init_completion(&zx_i2c->complete);
+	platform_set_drvdata(pdev, zx_i2c);
+
+	ret = zx2967_i2c_reset_hardware(zx_i2c);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to initialize i2c controller\n");
+		goto err_clk_unprepare;
+	}
+
+	ret = devm_request_irq(&pdev->dev, zx_i2c->irq,
+			zx2967_i2c_isr, 0, dev_name(&pdev->dev), zx_i2c);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to request irq %i\n", zx_i2c->irq);
+		goto err_clk_unprepare;
+	}
+
+	i2c_set_adapdata(&zx_i2c->adap, zx_i2c);
+	strlcpy(zx_i2c->adap.name, "zx2967 i2c adapter",
+		sizeof(zx_i2c->adap.name));
+	zx_i2c->adap.algo = &zx2967_i2c_algo;
+	zx_i2c->adap.nr = pdev->id;
+	zx_i2c->adap.dev.parent = &pdev->dev;
+	zx_i2c->adap.dev.of_node = pdev->dev.of_node;
+
+	ret = i2c_add_numbered_adapter(&zx_i2c->adap);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to add zx2967 i2c adapter\n");
+		goto err_clk_unprepare;
+	}
+
+	return 0;
+err_clk_unprepare:
+	clk_disable_unprepare(zx_i2c->clk);
+	return ret;
+}
+
+static int zx2967_i2c_remove(struct platform_device *pdev)
+{
+	struct zx2967_i2c_info *zx_i2c = platform_get_drvdata(pdev);
+
+	i2c_del_adapter(&zx_i2c->adap);
+	clk_disable_unprepare(zx_i2c->clk);
+
+	return 0;
+}
+
+static struct platform_driver zx2967_i2c_driver = {
+	.probe	= zx2967_i2c_probe,
+	.remove	= zx2967_i2c_remove,
+	.driver	= {
+		.name  = "zx2967_i2c",
+		.of_match_table = zx2967_i2c_of_match,
+		.pm = &zx2967_i2c_dev_pm_ops,
+	},
+};
+module_platform_driver(zx2967_i2c_driver);
+
+MODULE_AUTHOR("Baoyou Xie <baoyou.xie@linaro.org>");
+MODULE_DESCRIPTION("ZTE ZX2967 I2C Bus Controller driver");
+MODULE_LICENSE("GPL v2");