diff mbox series

[v2] i2c: virtio: add a virtio i2c frontend driver

Message ID c4bd4fd56df36864ed34d3572f00b2b838fd833a.1599795029.git.jie.deng@intel.com
State Superseded
Headers show
Series [v2] i2c: virtio: add a virtio i2c frontend driver | expand

Commit Message

Jie Deng Sept. 11, 2020, 3:48 a.m. UTC 
Add an I2C bus driver for virtio para-virtualization.

The controller can be emulated by the backend driver in
any device model software by following the virtio protocol.

This driver communicates with the backend driver through a
virtio I2C message structure which includes following parts:

- Header: i2c_msg addr, flags, len.
- Data buffer: the pointer to the I2C msg data.
- Status: the processing result from the backend.

People may implement different backend drivers to emulate
different controllers according to their needs. A backend
example can be found in the device model of the open source
project ACRN. For more information, please refer to
https://projectacrn.org.

The virtio device ID 34 is used for this I2C adpter since IDs
before 34 have been reserved by other virtio devices.

Co-developed-by: Conghui Chen <conghui.chen@intel.com>
Signed-off-by: Conghui Chen <conghui.chen@intel.com>
Signed-off-by: Jie Deng <jie.deng@intel.com>
Reviewed-by: Shuo Liu <shuo.a.liu@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
The device ID request:
	https://github.com/oasis-tcs/virtio-spec/issues/85 

Changes in v2:
	- Addressed comments received from Michael, Andy and Jason.

 drivers/i2c/busses/Kconfig      |  11 ++
 drivers/i2c/busses/Makefile     |   3 +
 drivers/i2c/busses/i2c-virtio.c | 271 ++++++++++++++++++++++++++++++++++++++++
 include/uapi/linux/virtio_ids.h |   1 +
 4 files changed, 286 insertions(+)
 create mode 100644 drivers/i2c/busses/i2c-virtio.c

Comments

Randy Dunlap Sept. 11, 2020, 3:53 a.m. UTC | #1 
On 9/10/20 8:48 PM, Jie Deng wrote:
> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
> index 293e7a0..70c8e30 100644
> --- a/drivers/i2c/busses/Kconfig
> +++ b/drivers/i2c/busses/Kconfig
> @@ -21,6 +21,17 @@ config I2C_ALI1535
>  	  This driver can also be built as a module.  If so, the module
>  	  will be called i2c-ali1535.
>  
> +config I2C_VIRTIO
> +	tristate "Virtio I2C Adapter"
> +	depends on VIRTIO
> +	help
> +	  If you say yes to this option, support will be included for the virtio
> +	  i2c adapter driver. The hardware can be emulated by any device model

	  I2C
preferably


> +	  software according to the virtio protocol.
> +
> +	  This driver can also be built as a module. If so, the module
> +	  will be called i2c-virtio.
> +
>  config I2C_ALI1563
>  	tristate "ALI 1563"
>  	depends on PCI


thanks.
Jie Deng Sept. 14, 2020, 1:16 a.m. UTC | #2 
On 2020/9/11 11:53, Randy Dunlap wrote:
> On 9/10/20 8:48 PM, Jie Deng wrote:
>> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
>> index 293e7a0..70c8e30 100644
>> --- a/drivers/i2c/busses/Kconfig
>> +++ b/drivers/i2c/busses/Kconfig
>> @@ -21,6 +21,17 @@ config I2C_ALI1535
>>   	  This driver can also be built as a module.  If so, the module
>>   	  will be called i2c-ali1535.
>>   
>> +config I2C_VIRTIO
>> +	tristate "Virtio I2C Adapter"
>> +	depends on VIRTIO
>> +	help
>> +	  If you say yes to this option, support will be included for the virtio
>> +	  i2c adapter driver. The hardware can be emulated by any device model
> 	  I2C
> preferably
>
I will fix this typo. Thank you.


>> +	  software according to the virtio protocol.
>> +
>> +	  This driver can also be built as a module. If so, the module
>> +	  will be called i2c-virtio.
>> +
>>   config I2C_ALI1563
>>   	tristate "ALI 1563"
>>   	depends on PCI
>
> thanks.
Jason Wang Sept. 14, 2020, 2:46 a.m. UTC | #3 
On 2020/9/11 上午11:48, Jie Deng wrote:
> Add an I2C bus driver for virtio para-virtualization.
>
> The controller can be emulated by the backend driver in
> any device model software by following the virtio protocol.
>
> This driver communicates with the backend driver through a
> virtio I2C message structure which includes following parts:
>
> - Header: i2c_msg addr, flags, len.
> - Data buffer: the pointer to the I2C msg data.
> - Status: the processing result from the backend.
>
> People may implement different backend drivers to emulate
> different controllers according to their needs. A backend
> example can be found in the device model of the open source
> project ACRN. For more information, please refer to
> https://projectacrn.org.
>
> The virtio device ID 34 is used for this I2C adpter since IDs
> before 34 have been reserved by other virtio devices.
>
> Co-developed-by: Conghui Chen <conghui.chen@intel.com>
> Signed-off-by: Conghui Chen <conghui.chen@intel.com>
> Signed-off-by: Jie Deng <jie.deng@intel.com>
> Reviewed-by: Shuo Liu <shuo.a.liu@intel.com>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---
> The device ID request:
> 	https://github.com/oasis-tcs/virtio-spec/issues/85
>
> Changes in v2:
> 	- Addressed comments received from Michael, Andy and Jason.
>
>   drivers/i2c/busses/Kconfig      |  11 ++
>   drivers/i2c/busses/Makefile     |   3 +
>   drivers/i2c/busses/i2c-virtio.c | 271 ++++++++++++++++++++++++++++++++++++++++
>   include/uapi/linux/virtio_ids.h |   1 +
>   4 files changed, 286 insertions(+)
>   create mode 100644 drivers/i2c/busses/i2c-virtio.c
>
> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
> index 293e7a0..70c8e30 100644
> --- a/drivers/i2c/busses/Kconfig
> +++ b/drivers/i2c/busses/Kconfig
> @@ -21,6 +21,17 @@ config I2C_ALI1535
>   	  This driver can also be built as a module.  If so, the module
>   	  will be called i2c-ali1535.
>   
> +config I2C_VIRTIO
> +	tristate "Virtio I2C Adapter"
> +	depends on VIRTIO
> +	help
> +	  If you say yes to this option, support will be included for the virtio
> +	  i2c adapter driver. The hardware can be emulated by any device model
> +	  software according to the virtio protocol.
> +
> +	  This driver can also be built as a module. If so, the module
> +	  will be called i2c-virtio.
> +
>   config I2C_ALI1563
>   	tristate "ALI 1563"
>   	depends on PCI
> diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
> index 19aff0e..821acfa 100644
> --- a/drivers/i2c/busses/Makefile
> +++ b/drivers/i2c/busses/Makefile
> @@ -6,6 +6,9 @@
>   # ACPI drivers
>   obj-$(CONFIG_I2C_SCMI)		+= i2c-scmi.o
>   
> +# VIRTIO I2C host controller driver
> +obj-$(CONFIG_I2C_VIRTIO)	+= i2c-virtio.o
> +
>   # PC SMBus host controller drivers
>   obj-$(CONFIG_I2C_ALI1535)	+= i2c-ali1535.o
>   obj-$(CONFIG_I2C_ALI1563)	+= i2c-ali1563.o
> diff --git a/drivers/i2c/busses/i2c-virtio.c b/drivers/i2c/busses/i2c-virtio.c
> new file mode 100644
> index 0000000..aff1a9a
> --- /dev/null
> +++ b/drivers/i2c/busses/i2c-virtio.c
> @@ -0,0 +1,271 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Virtio I2C Bus Driver
> + *
> + * Copyright (c) 2020 Intel Corporation. All rights reserved.
> + */
> +
> +#include <linux/acpi.h>
> +#include <linux/completion.h>
> +#include <linux/err.h>
> +#include <linux/i2c.h>
> +#include <linux/io.h>
> +#include <linux/jiffies.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/wait.h>
> +
> +#include <linux/virtio.h>
> +#include <linux/virtio_ids.h>
> +#include <linux/virtio_config.h>
> +
> +#define VIRTIO_I2C_MSG_OK	0
> +#define VIRTIO_I2C_MSG_ERR	1
> +
> +/**
> + * struct virtio_i2c_hdr - the virtio I2C message header structure
> + * @addr: i2c_msg addr, the slave address
> + * @flags: i2c_msg flags
> + * @len: i2c_msg len
> + */
> +struct virtio_i2c_hdr {
> +	__le16 addr;
> +	__le16 flags;
> +	__le16 len;
> +};


As said in v1, this should belong to uapi.


> +
> +/**
> + * struct virtio_i2c_msg - the virtio I2C message structure
> + * @hdr: the virtio I2C message header
> + * @buf: virtio I2C message data buffer
> + * @status: the processing result from the backend
> + */
> +struct virtio_i2c_msg {
> +	struct virtio_i2c_hdr hdr;
> +	u8 *buf;
> +	u8 status;
> +};


I'm not quite sure this is the best layout.

E.g virtio scsi differ in buffer out of out one:

structvirtio_scsi_req_cmd{
...
u8 dataout[];
...
u8 datain[];

}

And I would like to have a look at the spec patch.

Thanks


> +
> +/**
> + * struct virtio_i2c - virtio I2C data
> + * @vdev: virtio device for this controller
> + * @completion: completion of virtio I2C message
> + * @vmsg: the virtio I2C message for communication
> + * @adap: I2C adapter for this controller
> + * @i2c_lock: lock for virtqueue processing
> + * @vq: the virtio virtqueue for communication
> + */
> +struct virtio_i2c {
> +	struct virtio_device *vdev;
> +	struct completion completion;
> +	struct virtio_i2c_msg vmsg;
> +	struct i2c_adapter adap;
> +	struct mutex i2c_lock;
> +	struct virtqueue *vq;
> +};
> +
> +static void virtio_i2c_msg_done(struct virtqueue *vq)
> +{
> +	struct virtio_i2c *vi = vq->vdev->priv;
> +
> +	complete(&vi->completion);
> +}
> +
> +static int virtio_i2c_add_msg(struct virtqueue *vq,
> +			      struct virtio_i2c_msg *vmsg,
> +			      struct i2c_msg *msg)
> +{
> +	struct scatterlist *sgs[3], hdr, bout, bin, status;
> +	int outcnt = 0, incnt = 0;
> +
> +	if (!msg->len)
> +		return -EINVAL;
> +
> +	vmsg->hdr.addr = cpu_to_le16(msg->addr);
> +	vmsg->hdr.flags = cpu_to_le16(msg->flags);
> +	vmsg->hdr.len = cpu_to_le16(msg->len);
> +
> +	vmsg->buf = kzalloc(msg->len, GFP_KERNEL);
> +	if (!vmsg->buf)
> +		return -ENOMEM;
> +
> +	sg_init_one(&hdr, &vmsg->hdr, sizeof(struct virtio_i2c_hdr));
> +	sgs[outcnt++] = &hdr;
> +	if (msg->flags & I2C_M_RD) {
> +		sg_init_one(&bin, vmsg->buf, msg->len);
> +		sgs[outcnt + incnt++] = &bin;
> +	} else {
> +		memcpy(vmsg->buf, msg->buf, msg->len);
> +		sg_init_one(&bout, vmsg->buf, msg->len);
> +		sgs[outcnt++] = &bout;
> +	}
> +	sg_init_one(&status, &vmsg->status, sizeof(vmsg->status));
> +	sgs[outcnt + incnt++] = &status;
> +
> +	return virtqueue_add_sgs(vq, sgs, outcnt, incnt, vmsg, GFP_KERNEL);
> +}
> +
> +static int virtio_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
> +{
> +	struct virtio_i2c *vi = i2c_get_adapdata(adap);
> +	struct virtqueue *vq = vi->vq;
> +	struct virtio_i2c_msg *vmsg;
> +	unsigned long time_left;
> +	int len, i, ret = 0;
> +
> +	mutex_lock(&vi->i2c_lock);
> +	vmsg = &vi->vmsg;
> +	vmsg->buf = NULL;
> +
> +	for (i = 0; i < num; i++) {
> +		ret = virtio_i2c_add_msg(vq, vmsg, &msgs[i]);
> +		if (ret) {
> +			dev_err(&adap->dev, "failed to add msg[%d] to virtqueue.\n", i);
> +			break;
> +		}
> +
> +		virtqueue_kick(vq);
> +
> +		time_left = wait_for_completion_timeout(&vi->completion, adap->timeout);
> +		if (!time_left) {
> +			dev_err(&adap->dev, "msg[%d]: addr=0x%x timeout.\n", i, msgs[i].addr);
> +			break;
> +		}
> +
> +		vmsg = (struct virtio_i2c_msg *)virtqueue_get_buf(vq, &len);
> +		if (vmsg) {
> +			/* vmsg should point to the same address with &vi->vmsg */
> +			if (vmsg != &vi->vmsg) {
> +				dev_err(&adap->dev, "msg[%d]: addr=0x%x virtqueue error.\n",
> +					i, le16_to_cpu(vmsg->hdr.addr));
> +				break;
> +			}
> +			if (vmsg->status != VIRTIO_I2C_MSG_OK) {
> +				dev_err(&adap->dev, "msg[%d]: addr=0x%x error=%d.\n",
> +					i, le16_to_cpu(vmsg->hdr.addr), vmsg->status);
> +				break;
> +			}
> +			if ((msgs[i].flags & I2C_M_RD) && msgs[i].len)
> +				memcpy(msgs[i].buf, vmsg->buf, msgs[i].len);
> +
> +			kfree(vmsg->buf);
> +			vmsg->buf = NULL;
> +		}
> +
> +		reinit_completion(&vi->completion);
> +	}
> +
> +	mutex_unlock(&vi->i2c_lock);
> +	kfree(vmsg->buf);
> +	return ((ret < 0) ? ret : i);
> +}
> +
> +static void virtio_i2c_del_vqs(struct virtio_device *vdev)
> +{
> +	vdev->config->reset(vdev);
> +	vdev->config->del_vqs(vdev);
> +}
> +
> +static int virtio_i2c_setup_vqs(struct virtio_i2c *vi)
> +{
> +	struct virtio_device *vdev = vi->vdev;
> +
> +	vi->vq = virtio_find_single_vq(vdev, virtio_i2c_msg_done, "msg");
> +	return PTR_ERR_OR_ZERO(vi->vq);
> +}
> +
> +static u32 virtio_i2c_func(struct i2c_adapter *adap)
> +{
> +	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
> +}
> +
> +static struct i2c_algorithm virtio_algorithm = {
> +	.master_xfer = virtio_i2c_xfer,
> +	.functionality = virtio_i2c_func,
> +};
> +
> +static struct i2c_adapter virtio_adapter = {
> +	.owner = THIS_MODULE,
> +	.name = "Virtio I2C Adapter",
> +	.class = I2C_CLASS_DEPRECATED,
> +	.algo = &virtio_algorithm,
> +};
> +
> +static int virtio_i2c_probe(struct virtio_device *vdev)
> +{
> +	struct device *pdev = vdev->dev.parent;
> +	struct virtio_i2c *vi;
> +	int ret;
> +
> +	vi = devm_kzalloc(&vdev->dev, sizeof(*vi), GFP_KERNEL);
> +	if (!vi)
> +		return -ENOMEM;
> +
> +	vdev->priv = vi;
> +	vi->vdev = vdev;
> +
> +	mutex_init(&vi->i2c_lock);
> +	init_completion(&vi->completion);
> +
> +	ret = virtio_i2c_setup_vqs(vi);
> +	if (ret)
> +		return ret;
> +
> +	vi->adap = virtio_adapter;
> +	i2c_set_adapdata(&vi->adap, vi);
> +	vi->adap.dev.parent = &vdev->dev;
> +	/* Setup ACPI node for slave devices which will be probed through ACPI */
> +	ACPI_COMPANION_SET(&vi->adap.dev, ACPI_COMPANION(pdev));
> +	vi->adap.timeout = HZ / 10;
> +
> +	ret = i2c_add_adapter(&vi->adap);
> +	if (ret) {
> +		virtio_i2c_del_vqs(vdev);
> +		dev_err(&vdev->dev, "failed to add virtio-i2c adapter.\n");
> +	}
> +
> +	return ret;
> +}
> +
> +static void virtio_i2c_remove(struct virtio_device *vdev)
> +{
> +	struct virtio_i2c *vi = vdev->priv;
> +
> +	i2c_del_adapter(&vi->adap);
> +	virtio_i2c_del_vqs(vdev);
> +}
> +
> +static struct virtio_device_id id_table[] = {
> +	{ VIRTIO_ID_I2C_ADPTER, VIRTIO_DEV_ANY_ID },
> +	{}
> +};
> +MODULE_DEVICE_TABLE(virtio, id_table);
> +
> +static int __maybe_unused virtio_i2c_freeze(struct virtio_device *vdev)
> +{
> +	virtio_i2c_del_vqs(vdev);
> +	return 0;
> +}
> +
> +static int __maybe_unused virtio_i2c_restore(struct virtio_device *vdev)
> +{
> +	return virtio_i2c_setup_vqs(vdev->priv);
> +}
> +
> +static struct virtio_driver virtio_i2c_driver = {
> +	.id_table	= id_table,
> +	.probe		= virtio_i2c_probe,
> +	.remove		= virtio_i2c_remove,
> +	.driver	= {
> +		.name	= "i2c_virtio",
> +	},
> +#ifdef CONFIG_PM_SLEEP
> +	.freeze = virtio_i2c_freeze,
> +	.restore = virtio_i2c_restore,
> +#endif
> +};
> +module_virtio_driver(virtio_i2c_driver);
> +
> +MODULE_DESCRIPTION("Virtio i2c bus driver");
> +MODULE_LICENSE("GPL");
> diff --git a/include/uapi/linux/virtio_ids.h b/include/uapi/linux/virtio_ids.h
> index b052355..398ef2d 100644
> --- a/include/uapi/linux/virtio_ids.h
> +++ b/include/uapi/linux/virtio_ids.h
> @@ -48,5 +48,6 @@
>   #define VIRTIO_ID_FS           26 /* virtio filesystem */
>   #define VIRTIO_ID_PMEM         27 /* virtio pmem */
>   #define VIRTIO_ID_MAC80211_HWSIM 29 /* virtio mac80211-hwsim */
> +#define VIRTIO_ID_I2C_ADPTER   34 /* virtio i2c adpter */
>   
>   #endif /* _LINUX_VIRTIO_IDS_H */
Jie Deng Sept. 14, 2020, 3:43 a.m. UTC | #4 
On 2020/9/14 10:46, Jason Wang wrote:
>
>> +
>> +#define VIRTIO_I2C_MSG_OK    0
>> +#define VIRTIO_I2C_MSG_ERR    1
>> +
>> +/**
>> + * struct virtio_i2c_hdr - the virtio I2C message header structure
>> + * @addr: i2c_msg addr, the slave address
>> + * @flags: i2c_msg flags
>> + * @len: i2c_msg len
>> + */
>> +struct virtio_i2c_hdr {
>> +    __le16 addr;
>> +    __le16 flags;
>> +    __le16 len;
>> +};
>
>
> As said in v1, this should belong to uapi.
>
That's right. I missed this.
I will move these things to uapi. Thanks.


>
>> +
>> +/**
>> + * struct virtio_i2c_msg - the virtio I2C message structure
>> + * @hdr: the virtio I2C message header
>> + * @buf: virtio I2C message data buffer
>> + * @status: the processing result from the backend
>> + */
>> +struct virtio_i2c_msg {
>> +    struct virtio_i2c_hdr hdr;
>> +    u8 *buf;
>> +    u8 status;
>> +};
>
>
> I'm not quite sure this is the best layout.
>
> E.g virtio scsi differ in buffer out of out one:
>
> structvirtio_scsi_req_cmd{
> ...
> u8 dataout[];
> ...
> u8 datain[];
>
> }
>
> And I would like to have a look at the spec patch.
>
> Thanks
>
Sure. I will send the v3 along with the spec patch.
Thanks.
Dan Carpenter Sept. 14, 2020, 2:48 p.m. UTC | #5 
Hi Jie,

url:    https://github.com/0day-ci/linux/commits/Jie-Deng/i2c-virtio-add-a-virtio-i2c-frontend-driver/20200911-115013
base:   https://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux.git i2c/for-next
config: parisc-randconfig-m031-20200913 (attached as .config)
compiler: hppa-linux-gcc (GCC) 9.3.0

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>

smatch warnings:
drivers/i2c/busses/i2c-virtio.c:160 virtio_i2c_xfer() error: we previously assumed 'vmsg' could be null (see line 137)

# https://github.com/0day-ci/linux/commit/0a54ec771966748fcbc86256b830b5f786168b7d
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Jie-Deng/i2c-virtio-add-a-virtio-i2c-frontend-driver/20200911-115013
git checkout 0a54ec771966748fcbc86256b830b5f786168b7d
vim +/vmsg +160 drivers/i2c/busses/i2c-virtio.c

0a54ec77196674 Jie Deng 2020-09-11  109  static int virtio_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
0a54ec77196674 Jie Deng 2020-09-11  110  {
0a54ec77196674 Jie Deng 2020-09-11  111  	struct virtio_i2c *vi = i2c_get_adapdata(adap);
0a54ec77196674 Jie Deng 2020-09-11  112  	struct virtqueue *vq = vi->vq;
0a54ec77196674 Jie Deng 2020-09-11  113  	struct virtio_i2c_msg *vmsg;
0a54ec77196674 Jie Deng 2020-09-11  114  	unsigned long time_left;
0a54ec77196674 Jie Deng 2020-09-11  115  	int len, i, ret = 0;
0a54ec77196674 Jie Deng 2020-09-11  116  
0a54ec77196674 Jie Deng 2020-09-11  117  	mutex_lock(&vi->i2c_lock);
0a54ec77196674 Jie Deng 2020-09-11  118  	vmsg = &vi->vmsg;
0a54ec77196674 Jie Deng 2020-09-11  119  	vmsg->buf = NULL;
0a54ec77196674 Jie Deng 2020-09-11  120  
0a54ec77196674 Jie Deng 2020-09-11  121  	for (i = 0; i < num; i++) {
0a54ec77196674 Jie Deng 2020-09-11  122  		ret = virtio_i2c_add_msg(vq, vmsg, &msgs[i]);
0a54ec77196674 Jie Deng 2020-09-11  123  		if (ret) {
0a54ec77196674 Jie Deng 2020-09-11  124  			dev_err(&adap->dev, "failed to add msg[%d] to virtqueue.\n", i);
0a54ec77196674 Jie Deng 2020-09-11  125  			break;
0a54ec77196674 Jie Deng 2020-09-11  126  		}
0a54ec77196674 Jie Deng 2020-09-11  127  
0a54ec77196674 Jie Deng 2020-09-11  128  		virtqueue_kick(vq);
0a54ec77196674 Jie Deng 2020-09-11  129  
0a54ec77196674 Jie Deng 2020-09-11  130  		time_left = wait_for_completion_timeout(&vi->completion, adap->timeout);
0a54ec77196674 Jie Deng 2020-09-11  131  		if (!time_left) {
0a54ec77196674 Jie Deng 2020-09-11  132  			dev_err(&adap->dev, "msg[%d]: addr=0x%x timeout.\n", i, msgs[i].addr);
0a54ec77196674 Jie Deng 2020-09-11  133  			break;
0a54ec77196674 Jie Deng 2020-09-11  134  		}
0a54ec77196674 Jie Deng 2020-09-11  135  
0a54ec77196674 Jie Deng 2020-09-11  136  		vmsg = (struct virtio_i2c_msg *)virtqueue_get_buf(vq, &len);
0a54ec77196674 Jie Deng 2020-09-11 @137  		if (vmsg) {
                                                            ^^^^
Check for NULL.

0a54ec77196674 Jie Deng 2020-09-11  138  			/* vmsg should point to the same address with &vi->vmsg */
0a54ec77196674 Jie Deng 2020-09-11  139  			if (vmsg != &vi->vmsg) {
0a54ec77196674 Jie Deng 2020-09-11  140  				dev_err(&adap->dev, "msg[%d]: addr=0x%x virtqueue error.\n",
0a54ec77196674 Jie Deng 2020-09-11  141  					i, le16_to_cpu(vmsg->hdr.addr));
0a54ec77196674 Jie Deng 2020-09-11  142  				break;
0a54ec77196674 Jie Deng 2020-09-11  143  			}
0a54ec77196674 Jie Deng 2020-09-11  144  			if (vmsg->status != VIRTIO_I2C_MSG_OK) {
0a54ec77196674 Jie Deng 2020-09-11  145  				dev_err(&adap->dev, "msg[%d]: addr=0x%x error=%d.\n",
0a54ec77196674 Jie Deng 2020-09-11  146  					i, le16_to_cpu(vmsg->hdr.addr), vmsg->status);
0a54ec77196674 Jie Deng 2020-09-11  147  				break;
0a54ec77196674 Jie Deng 2020-09-11  148  			}
0a54ec77196674 Jie Deng 2020-09-11  149  			if ((msgs[i].flags & I2C_M_RD) && msgs[i].len)
0a54ec77196674 Jie Deng 2020-09-11  150  				memcpy(msgs[i].buf, vmsg->buf, msgs[i].len);
0a54ec77196674 Jie Deng 2020-09-11  151  
0a54ec77196674 Jie Deng 2020-09-11  152  			kfree(vmsg->buf);
0a54ec77196674 Jie Deng 2020-09-11  153  			vmsg->buf = NULL;
0a54ec77196674 Jie Deng 2020-09-11  154  		}
0a54ec77196674 Jie Deng 2020-09-11  155  
0a54ec77196674 Jie Deng 2020-09-11  156  		reinit_completion(&vi->completion);
0a54ec77196674 Jie Deng 2020-09-11  157  	}
0a54ec77196674 Jie Deng 2020-09-11  158  
0a54ec77196674 Jie Deng 2020-09-11  159  	mutex_unlock(&vi->i2c_lock);
0a54ec77196674 Jie Deng 2020-09-11 @160  	kfree(vmsg->buf);
                                                      ^^^^^^^^^
Unchecked dereference.

0a54ec77196674 Jie Deng 2020-09-11  161  	return ((ret < 0) ? ret : i);
0a54ec77196674 Jie Deng 2020-09-11  162  }

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
Dan Carpenter Sept. 14, 2020, 3:47 p.m. UTC | #6 
On Mon, Sep 14, 2020 at 06:24:55PM +0300, Andy Shevchenko wrote:
> On Mon, Sep 14, 2020 at 05:48:07PM +0300, Dan Carpenter wrote:
> > Hi Jie,
> > 
> > url:    https://github.com/0day-ci/linux/commits/Jie-Deng/i2c-virtio-add-a-virtio-i2c-frontend-driver/20200911-115013 
> > base:   https://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux.git  i2c/for-next
> > config: parisc-randconfig-m031-20200913 (attached as .config)
> > compiler: hppa-linux-gcc (GCC) 9.3.0
> > 
> > If you fix the issue, kindly add following tag as appropriate
> > Reported-by: kernel test robot <lkp@intel.com>
> > Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> > 
> > smatch warnings:
> > drivers/i2c/busses/i2c-virtio.c:160 virtio_i2c_xfer() error: we previously assumed 'vmsg' could be null (see line 137)
> > 
> 
> It's quite possible a false positive. Look at 122. But I agree that for-loop is
> not the best for such things to understand. Perhaps switching to do {} while ()
> will make it better.
> 

Smatch is assuming that virtqueue_get_buf() can return NULL on the last
iteration through the loop.

regards,
dan carpenter


> > # https://github.com/0day-ci/linux/commit/0a54ec771966748fcbc86256b830b5f786168b7d 
> > git remote add linux-review https://github.com/0day-ci/linux 
> > git fetch --no-tags linux-review Jie-Deng/i2c-virtio-add-a-virtio-i2c-frontend-driver/20200911-115013
> > git checkout 0a54ec771966748fcbc86256b830b5f786168b7d
> > vim +/vmsg +160 drivers/i2c/busses/i2c-virtio.c
> > 
> > 0a54ec77196674 Jie Deng 2020-09-11  109  static int virtio_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
> > 0a54ec77196674 Jie Deng 2020-09-11  110  {
> > 0a54ec77196674 Jie Deng 2020-09-11  111  	struct virtio_i2c *vi = i2c_get_adapdata(adap);
> > 0a54ec77196674 Jie Deng 2020-09-11  112  	struct virtqueue *vq = vi->vq;
> > 0a54ec77196674 Jie Deng 2020-09-11  113  	struct virtio_i2c_msg *vmsg;
> > 0a54ec77196674 Jie Deng 2020-09-11  114  	unsigned long time_left;
> > 0a54ec77196674 Jie Deng 2020-09-11  115  	int len, i, ret = 0;
> > 0a54ec77196674 Jie Deng 2020-09-11  116  
> > 0a54ec77196674 Jie Deng 2020-09-11  117  	mutex_lock(&vi->i2c_lock);
> > 0a54ec77196674 Jie Deng 2020-09-11  118  	vmsg = &vi->vmsg;
> > 0a54ec77196674 Jie Deng 2020-09-11  119  	vmsg->buf = NULL;
> > 0a54ec77196674 Jie Deng 2020-09-11  120  
> > 0a54ec77196674 Jie Deng 2020-09-11  121  	for (i = 0; i < num; i++) {
> > 0a54ec77196674 Jie Deng 2020-09-11  122  		ret = virtio_i2c_add_msg(vq, vmsg, &msgs[i]);
> > 0a54ec77196674 Jie Deng 2020-09-11  123  		if (ret) {
> > 0a54ec77196674 Jie Deng 2020-09-11  124  			dev_err(&adap->dev, "failed to add msg[%d] to virtqueue.\n", i);
> > 0a54ec77196674 Jie Deng 2020-09-11  125  			break;
> > 0a54ec77196674 Jie Deng 2020-09-11  126  		}
> > 0a54ec77196674 Jie Deng 2020-09-11  127  
> > 0a54ec77196674 Jie Deng 2020-09-11  128  		virtqueue_kick(vq);
> > 0a54ec77196674 Jie Deng 2020-09-11  129  
> > 0a54ec77196674 Jie Deng 2020-09-11  130  		time_left = wait_for_completion_timeout(&vi->completion, adap->timeout);
> > 0a54ec77196674 Jie Deng 2020-09-11  131  		if (!time_left) {
> > 0a54ec77196674 Jie Deng 2020-09-11  132  			dev_err(&adap->dev, "msg[%d]: addr=0x%x timeout.\n", i, msgs[i].addr);
> > 0a54ec77196674 Jie Deng 2020-09-11  133  			break;
> > 0a54ec77196674 Jie Deng 2020-09-11  134  		}
> > 0a54ec77196674 Jie Deng 2020-09-11  135  
> > 0a54ec77196674 Jie Deng 2020-09-11  136  		vmsg = (struct virtio_i2c_msg *)virtqueue_get_buf(vq, &len);
> > 0a54ec77196674 Jie Deng 2020-09-11 @137  		if (vmsg) {
> >                                                             ^^^^
> > Check for NULL.
> > 
> > 0a54ec77196674 Jie Deng 2020-09-11  138  			/* vmsg should point to the same address with &vi->vmsg */
> > 0a54ec77196674 Jie Deng 2020-09-11  139  			if (vmsg != &vi->vmsg) {
> > 0a54ec77196674 Jie Deng 2020-09-11  140  				dev_err(&adap->dev, "msg[%d]: addr=0x%x virtqueue error.\n",
> > 0a54ec77196674 Jie Deng 2020-09-11  141  					i, le16_to_cpu(vmsg->hdr.addr));
> > 0a54ec77196674 Jie Deng 2020-09-11  142  				break;
> > 0a54ec77196674 Jie Deng 2020-09-11  143  			}
> > 0a54ec77196674 Jie Deng 2020-09-11  144  			if (vmsg->status != VIRTIO_I2C_MSG_OK) {
> > 0a54ec77196674 Jie Deng 2020-09-11  145  				dev_err(&adap->dev, "msg[%d]: addr=0x%x error=%d.\n",
> > 0a54ec77196674 Jie Deng 2020-09-11  146  					i, le16_to_cpu(vmsg->hdr.addr), vmsg->status);
> > 0a54ec77196674 Jie Deng 2020-09-11  147  				break;
> > 0a54ec77196674 Jie Deng 2020-09-11  148  			}
> > 0a54ec77196674 Jie Deng 2020-09-11  149  			if ((msgs[i].flags & I2C_M_RD) && msgs[i].len)
> > 0a54ec77196674 Jie Deng 2020-09-11  150  				memcpy(msgs[i].buf, vmsg->buf, msgs[i].len);
> > 0a54ec77196674 Jie Deng 2020-09-11  151  
> > 0a54ec77196674 Jie Deng 2020-09-11  152  			kfree(vmsg->buf);
> > 0a54ec77196674 Jie Deng 2020-09-11  153  			vmsg->buf = NULL;
> > 0a54ec77196674 Jie Deng 2020-09-11  154  		}
> > 0a54ec77196674 Jie Deng 2020-09-11  155  
> > 0a54ec77196674 Jie Deng 2020-09-11  156  		reinit_completion(&vi->completion);
> > 0a54ec77196674 Jie Deng 2020-09-11  157  	}
> > 0a54ec77196674 Jie Deng 2020-09-11  158  
> > 0a54ec77196674 Jie Deng 2020-09-11  159  	mutex_unlock(&vi->i2c_lock);
> > 0a54ec77196674 Jie Deng 2020-09-11 @160  	kfree(vmsg->buf);
> >                                                       ^^^^^^^^^
> > Unchecked dereference.
> > 
> > 0a54ec77196674 Jie Deng 2020-09-11  161  	return ((ret < 0) ? ret : i);
> > 0a54ec77196674 Jie Deng 2020-09-11  162  }
> > 
> > ---
> > 0-DAY CI Kernel Test Service, Intel Corporation
> > https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org 
> 
> 
> 
> -- 
> With Best Regards,
> Andy Shevchenko
>
Andy Shevchenko Sept. 14, 2020, 4:08 p.m. UTC | #7 
On Mon, Sep 14, 2020 at 06:47:27PM +0300, Dan Carpenter wrote:
> On Mon, Sep 14, 2020 at 06:24:55PM +0300, Andy Shevchenko wrote:
> > On Mon, Sep 14, 2020 at 05:48:07PM +0300, Dan Carpenter wrote:
> > > Hi Jie,
> > > 
> > > url:    https://github.com/0day-ci/linux/commits/Jie-Deng/i2c-virtio-add-a-virtio-i2c-frontend-driver/20200911-115013 
> > > base:   https://git.kernel.org/pub/scm/linux/kernel/git/wsa/linux.git  i2c/for-next
> > > config: parisc-randconfig-m031-20200913 (attached as .config)
> > > compiler: hppa-linux-gcc (GCC) 9.3.0
> > > 
> > > If you fix the issue, kindly add following tag as appropriate
> > > Reported-by: kernel test robot <lkp@intel.com>
> > > Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
> > > 
> > > smatch warnings:
> > > drivers/i2c/busses/i2c-virtio.c:160 virtio_i2c_xfer() error: we previously assumed 'vmsg' could be null (see line 137)
> > > 
> > 
> > It's quite possible a false positive. Look at 122. But I agree that for-loop is
> > not the best for such things to understand. Perhaps switching to do {} while ()
> > will make it better.
> > 
> 
> Smatch is assuming that virtqueue_get_buf() can return NULL on the last
> iteration through the loop.

I see now. Thanks.

> > > # https://github.com/0day-ci/linux/commit/0a54ec771966748fcbc86256b830b5f786168b7d 
> > > git remote add linux-review https://github.com/0day-ci/linux 
> > > git fetch --no-tags linux-review Jie-Deng/i2c-virtio-add-a-virtio-i2c-frontend-driver/20200911-115013
> > > git checkout 0a54ec771966748fcbc86256b830b5f786168b7d
> > > vim +/vmsg +160 drivers/i2c/busses/i2c-virtio.c
> > > 
> > > 0a54ec77196674 Jie Deng 2020-09-11  109  static int virtio_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
> > > 0a54ec77196674 Jie Deng 2020-09-11  110  {
> > > 0a54ec77196674 Jie Deng 2020-09-11  111  	struct virtio_i2c *vi = i2c_get_adapdata(adap);
> > > 0a54ec77196674 Jie Deng 2020-09-11  112  	struct virtqueue *vq = vi->vq;
> > > 0a54ec77196674 Jie Deng 2020-09-11  113  	struct virtio_i2c_msg *vmsg;
> > > 0a54ec77196674 Jie Deng 2020-09-11  114  	unsigned long time_left;
> > > 0a54ec77196674 Jie Deng 2020-09-11  115  	int len, i, ret = 0;
> > > 0a54ec77196674 Jie Deng 2020-09-11  116  
> > > 0a54ec77196674 Jie Deng 2020-09-11  117  	mutex_lock(&vi->i2c_lock);
> > > 0a54ec77196674 Jie Deng 2020-09-11  118  	vmsg = &vi->vmsg;
> > > 0a54ec77196674 Jie Deng 2020-09-11  119  	vmsg->buf = NULL;
> > > 0a54ec77196674 Jie Deng 2020-09-11  120  
> > > 0a54ec77196674 Jie Deng 2020-09-11  121  	for (i = 0; i < num; i++) {
> > > 0a54ec77196674 Jie Deng 2020-09-11  122  		ret = virtio_i2c_add_msg(vq, vmsg, &msgs[i]);
> > > 0a54ec77196674 Jie Deng 2020-09-11  123  		if (ret) {
> > > 0a54ec77196674 Jie Deng 2020-09-11  124  			dev_err(&adap->dev, "failed to add msg[%d] to virtqueue.\n", i);
> > > 0a54ec77196674 Jie Deng 2020-09-11  125  			break;
> > > 0a54ec77196674 Jie Deng 2020-09-11  126  		}
> > > 0a54ec77196674 Jie Deng 2020-09-11  127  
> > > 0a54ec77196674 Jie Deng 2020-09-11  128  		virtqueue_kick(vq);
> > > 0a54ec77196674 Jie Deng 2020-09-11  129  
> > > 0a54ec77196674 Jie Deng 2020-09-11  130  		time_left = wait_for_completion_timeout(&vi->completion, adap->timeout);
> > > 0a54ec77196674 Jie Deng 2020-09-11  131  		if (!time_left) {
> > > 0a54ec77196674 Jie Deng 2020-09-11  132  			dev_err(&adap->dev, "msg[%d]: addr=0x%x timeout.\n", i, msgs[i].addr);
> > > 0a54ec77196674 Jie Deng 2020-09-11  133  			break;
> > > 0a54ec77196674 Jie Deng 2020-09-11  134  		}
> > > 0a54ec77196674 Jie Deng 2020-09-11  135  
> > > 0a54ec77196674 Jie Deng 2020-09-11  136  		vmsg = (struct virtio_i2c_msg *)virtqueue_get_buf(vq, &len);
> > > 0a54ec77196674 Jie Deng 2020-09-11 @137  		if (vmsg) {
> > >                                                             ^^^^
> > > Check for NULL.
> > > 
> > > 0a54ec77196674 Jie Deng 2020-09-11  138  			/* vmsg should point to the same address with &vi->vmsg */
> > > 0a54ec77196674 Jie Deng 2020-09-11  139  			if (vmsg != &vi->vmsg) {
> > > 0a54ec77196674 Jie Deng 2020-09-11  140  				dev_err(&adap->dev, "msg[%d]: addr=0x%x virtqueue error.\n",
> > > 0a54ec77196674 Jie Deng 2020-09-11  141  					i, le16_to_cpu(vmsg->hdr.addr));
> > > 0a54ec77196674 Jie Deng 2020-09-11  142  				break;
> > > 0a54ec77196674 Jie Deng 2020-09-11  143  			}
> > > 0a54ec77196674 Jie Deng 2020-09-11  144  			if (vmsg->status != VIRTIO_I2C_MSG_OK) {
> > > 0a54ec77196674 Jie Deng 2020-09-11  145  				dev_err(&adap->dev, "msg[%d]: addr=0x%x error=%d.\n",
> > > 0a54ec77196674 Jie Deng 2020-09-11  146  					i, le16_to_cpu(vmsg->hdr.addr), vmsg->status);
> > > 0a54ec77196674 Jie Deng 2020-09-11  147  				break;
> > > 0a54ec77196674 Jie Deng 2020-09-11  148  			}
> > > 0a54ec77196674 Jie Deng 2020-09-11  149  			if ((msgs[i].flags & I2C_M_RD) && msgs[i].len)
> > > 0a54ec77196674 Jie Deng 2020-09-11  150  				memcpy(msgs[i].buf, vmsg->buf, msgs[i].len);
> > > 0a54ec77196674 Jie Deng 2020-09-11  151  
> > > 0a54ec77196674 Jie Deng 2020-09-11  152  			kfree(vmsg->buf);
> > > 0a54ec77196674 Jie Deng 2020-09-11  153  			vmsg->buf = NULL;
> > > 0a54ec77196674 Jie Deng 2020-09-11  154  		}
> > > 0a54ec77196674 Jie Deng 2020-09-11  155  
> > > 0a54ec77196674 Jie Deng 2020-09-11  156  		reinit_completion(&vi->completion);
> > > 0a54ec77196674 Jie Deng 2020-09-11  157  	}
> > > 0a54ec77196674 Jie Deng 2020-09-11  158  
> > > 0a54ec77196674 Jie Deng 2020-09-11  159  	mutex_unlock(&vi->i2c_lock);
> > > 0a54ec77196674 Jie Deng 2020-09-11 @160  	kfree(vmsg->buf);
> > >                                                       ^^^^^^^^^
> > > Unchecked dereference.
> > > 
> > > 0a54ec77196674 Jie Deng 2020-09-11  161  	return ((ret < 0) ? ret : i);
> > > 0a54ec77196674 Jie Deng 2020-09-11  162  }
> > > 
> > > ---
> > > 0-DAY CI Kernel Test Service, Intel Corporation
> > > https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org 
> > 
> > 
> > 
> > -- 
> > With Best Regards,
> > Andy Shevchenko
> >
diff mbox series

Patch

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 293e7a0..70c8e30 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -21,6 +21,17 @@  config I2C_ALI1535
 	  This driver can also be built as a module.  If so, the module
 	  will be called i2c-ali1535.
 
+config I2C_VIRTIO
+	tristate "Virtio I2C Adapter"
+	depends on VIRTIO
+	help
+	  If you say yes to this option, support will be included for the virtio
+	  i2c adapter driver. The hardware can be emulated by any device model
+	  software according to the virtio protocol.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called i2c-virtio.
+
 config I2C_ALI1563
 	tristate "ALI 1563"
 	depends on PCI
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 19aff0e..821acfa 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -6,6 +6,9 @@ 
 # ACPI drivers
 obj-$(CONFIG_I2C_SCMI)		+= i2c-scmi.o
 
+# VIRTIO I2C host controller driver
+obj-$(CONFIG_I2C_VIRTIO)	+= i2c-virtio.o
+
 # PC SMBus host controller drivers
 obj-$(CONFIG_I2C_ALI1535)	+= i2c-ali1535.o
 obj-$(CONFIG_I2C_ALI1563)	+= i2c-ali1563.o
diff --git a/drivers/i2c/busses/i2c-virtio.c b/drivers/i2c/busses/i2c-virtio.c
new file mode 100644
index 0000000..aff1a9a
--- /dev/null
+++ b/drivers/i2c/busses/i2c-virtio.c
@@ -0,0 +1,271 @@ 
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Virtio I2C Bus Driver
+ *
+ * Copyright (c) 2020 Intel Corporation. All rights reserved.
+ */
+
+#include <linux/acpi.h>
+#include <linux/completion.h>
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/io.h>
+#include <linux/jiffies.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/wait.h>
+
+#include <linux/virtio.h>
+#include <linux/virtio_ids.h>
+#include <linux/virtio_config.h>
+
+#define VIRTIO_I2C_MSG_OK	0
+#define VIRTIO_I2C_MSG_ERR	1
+
+/**
+ * struct virtio_i2c_hdr - the virtio I2C message header structure
+ * @addr: i2c_msg addr, the slave address
+ * @flags: i2c_msg flags
+ * @len: i2c_msg len
+ */
+struct virtio_i2c_hdr {
+	__le16 addr;
+	__le16 flags;
+	__le16 len;
+};
+
+/**
+ * struct virtio_i2c_msg - the virtio I2C message structure
+ * @hdr: the virtio I2C message header
+ * @buf: virtio I2C message data buffer
+ * @status: the processing result from the backend
+ */
+struct virtio_i2c_msg {
+	struct virtio_i2c_hdr hdr;
+	u8 *buf;
+	u8 status;
+};
+
+/**
+ * struct virtio_i2c - virtio I2C data
+ * @vdev: virtio device for this controller
+ * @completion: completion of virtio I2C message
+ * @vmsg: the virtio I2C message for communication
+ * @adap: I2C adapter for this controller
+ * @i2c_lock: lock for virtqueue processing
+ * @vq: the virtio virtqueue for communication
+ */
+struct virtio_i2c {
+	struct virtio_device *vdev;
+	struct completion completion;
+	struct virtio_i2c_msg vmsg;
+	struct i2c_adapter adap;
+	struct mutex i2c_lock;
+	struct virtqueue *vq;
+};
+
+static void virtio_i2c_msg_done(struct virtqueue *vq)
+{
+	struct virtio_i2c *vi = vq->vdev->priv;
+
+	complete(&vi->completion);
+}
+
+static int virtio_i2c_add_msg(struct virtqueue *vq,
+			      struct virtio_i2c_msg *vmsg,
+			      struct i2c_msg *msg)
+{
+	struct scatterlist *sgs[3], hdr, bout, bin, status;
+	int outcnt = 0, incnt = 0;
+
+	if (!msg->len)
+		return -EINVAL;
+
+	vmsg->hdr.addr = cpu_to_le16(msg->addr);
+	vmsg->hdr.flags = cpu_to_le16(msg->flags);
+	vmsg->hdr.len = cpu_to_le16(msg->len);
+
+	vmsg->buf = kzalloc(msg->len, GFP_KERNEL);
+	if (!vmsg->buf)
+		return -ENOMEM;
+
+	sg_init_one(&hdr, &vmsg->hdr, sizeof(struct virtio_i2c_hdr));
+	sgs[outcnt++] = &hdr;
+	if (msg->flags & I2C_M_RD) {
+		sg_init_one(&bin, vmsg->buf, msg->len);
+		sgs[outcnt + incnt++] = &bin;
+	} else {
+		memcpy(vmsg->buf, msg->buf, msg->len);
+		sg_init_one(&bout, vmsg->buf, msg->len);
+		sgs[outcnt++] = &bout;
+	}
+	sg_init_one(&status, &vmsg->status, sizeof(vmsg->status));
+	sgs[outcnt + incnt++] = &status;
+
+	return virtqueue_add_sgs(vq, sgs, outcnt, incnt, vmsg, GFP_KERNEL);
+}
+
+static int virtio_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
+{
+	struct virtio_i2c *vi = i2c_get_adapdata(adap);
+	struct virtqueue *vq = vi->vq;
+	struct virtio_i2c_msg *vmsg;
+	unsigned long time_left;
+	int len, i, ret = 0;
+
+	mutex_lock(&vi->i2c_lock);
+	vmsg = &vi->vmsg;
+	vmsg->buf = NULL;
+
+	for (i = 0; i < num; i++) {
+		ret = virtio_i2c_add_msg(vq, vmsg, &msgs[i]);
+		if (ret) {
+			dev_err(&adap->dev, "failed to add msg[%d] to virtqueue.\n", i);
+			break;
+		}
+
+		virtqueue_kick(vq);
+
+		time_left = wait_for_completion_timeout(&vi->completion, adap->timeout);
+		if (!time_left) {
+			dev_err(&adap->dev, "msg[%d]: addr=0x%x timeout.\n", i, msgs[i].addr);
+			break;
+		}
+
+		vmsg = (struct virtio_i2c_msg *)virtqueue_get_buf(vq, &len);
+		if (vmsg) {
+			/* vmsg should point to the same address with &vi->vmsg */
+			if (vmsg != &vi->vmsg) {
+				dev_err(&adap->dev, "msg[%d]: addr=0x%x virtqueue error.\n",
+					i, le16_to_cpu(vmsg->hdr.addr));
+				break;
+			}
+			if (vmsg->status != VIRTIO_I2C_MSG_OK) {
+				dev_err(&adap->dev, "msg[%d]: addr=0x%x error=%d.\n",
+					i, le16_to_cpu(vmsg->hdr.addr), vmsg->status);
+				break;
+			}
+			if ((msgs[i].flags & I2C_M_RD) && msgs[i].len)
+				memcpy(msgs[i].buf, vmsg->buf, msgs[i].len);
+
+			kfree(vmsg->buf);
+			vmsg->buf = NULL;
+		}
+
+		reinit_completion(&vi->completion);
+	}
+
+	mutex_unlock(&vi->i2c_lock);
+	kfree(vmsg->buf);
+	return ((ret < 0) ? ret : i);
+}
+
+static void virtio_i2c_del_vqs(struct virtio_device *vdev)
+{
+	vdev->config->reset(vdev);
+	vdev->config->del_vqs(vdev);
+}
+
+static int virtio_i2c_setup_vqs(struct virtio_i2c *vi)
+{
+	struct virtio_device *vdev = vi->vdev;
+
+	vi->vq = virtio_find_single_vq(vdev, virtio_i2c_msg_done, "msg");
+	return PTR_ERR_OR_ZERO(vi->vq);
+}
+
+static u32 virtio_i2c_func(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static struct i2c_algorithm virtio_algorithm = {
+	.master_xfer = virtio_i2c_xfer,
+	.functionality = virtio_i2c_func,
+};
+
+static struct i2c_adapter virtio_adapter = {
+	.owner = THIS_MODULE,
+	.name = "Virtio I2C Adapter",
+	.class = I2C_CLASS_DEPRECATED,
+	.algo = &virtio_algorithm,
+};
+
+static int virtio_i2c_probe(struct virtio_device *vdev)
+{
+	struct device *pdev = vdev->dev.parent;
+	struct virtio_i2c *vi;
+	int ret;
+
+	vi = devm_kzalloc(&vdev->dev, sizeof(*vi), GFP_KERNEL);
+	if (!vi)
+		return -ENOMEM;
+
+	vdev->priv = vi;
+	vi->vdev = vdev;
+
+	mutex_init(&vi->i2c_lock);
+	init_completion(&vi->completion);
+
+	ret = virtio_i2c_setup_vqs(vi);
+	if (ret)
+		return ret;
+
+	vi->adap = virtio_adapter;
+	i2c_set_adapdata(&vi->adap, vi);
+	vi->adap.dev.parent = &vdev->dev;
+	/* Setup ACPI node for slave devices which will be probed through ACPI */
+	ACPI_COMPANION_SET(&vi->adap.dev, ACPI_COMPANION(pdev));
+	vi->adap.timeout = HZ / 10;
+
+	ret = i2c_add_adapter(&vi->adap);
+	if (ret) {
+		virtio_i2c_del_vqs(vdev);
+		dev_err(&vdev->dev, "failed to add virtio-i2c adapter.\n");
+	}
+
+	return ret;
+}
+
+static void virtio_i2c_remove(struct virtio_device *vdev)
+{
+	struct virtio_i2c *vi = vdev->priv;
+
+	i2c_del_adapter(&vi->adap);
+	virtio_i2c_del_vqs(vdev);
+}
+
+static struct virtio_device_id id_table[] = {
+	{ VIRTIO_ID_I2C_ADPTER, VIRTIO_DEV_ANY_ID },
+	{}
+};
+MODULE_DEVICE_TABLE(virtio, id_table);
+
+static int __maybe_unused virtio_i2c_freeze(struct virtio_device *vdev)
+{
+	virtio_i2c_del_vqs(vdev);
+	return 0;
+}
+
+static int __maybe_unused virtio_i2c_restore(struct virtio_device *vdev)
+{
+	return virtio_i2c_setup_vqs(vdev->priv);
+}
+
+static struct virtio_driver virtio_i2c_driver = {
+	.id_table	= id_table,
+	.probe		= virtio_i2c_probe,
+	.remove		= virtio_i2c_remove,
+	.driver	= {
+		.name	= "i2c_virtio",
+	},
+#ifdef CONFIG_PM_SLEEP
+	.freeze = virtio_i2c_freeze,
+	.restore = virtio_i2c_restore,
+#endif
+};
+module_virtio_driver(virtio_i2c_driver);
+
+MODULE_DESCRIPTION("Virtio i2c bus driver");
+MODULE_LICENSE("GPL");
diff --git a/include/uapi/linux/virtio_ids.h b/include/uapi/linux/virtio_ids.h
index b052355..398ef2d 100644
--- a/include/uapi/linux/virtio_ids.h
+++ b/include/uapi/linux/virtio_ids.h
@@ -48,5 +48,6 @@ 
 #define VIRTIO_ID_FS           26 /* virtio filesystem */
 #define VIRTIO_ID_PMEM         27 /* virtio pmem */
 #define VIRTIO_ID_MAC80211_HWSIM 29 /* virtio mac80211-hwsim */
+#define VIRTIO_ID_I2C_ADPTER   34 /* virtio i2c adpter */
 
 #endif /* _LINUX_VIRTIO_IDS_H */