On 2021/3/4 14:06, Viresh Kumar wrote:> Please always supply version history, it makes it difficult to review
otherwise.
I will add the history.>> drivers/i2c/busses/Kconfig | 11 ++
>> drivers/i2c/busses/Makefile | 3 +
>> drivers/i2c/busses/i2c-virtio.c | 289
++++++++++++++++++++++++++++++++++++++++
>> include/uapi/linux/virtio_i2c.h | 42 ++++++
>> include/uapi/linux/virtio_ids.h | 1 +
>> 5 files changed, 346 insertions(+)
>> create mode 100644 drivers/i2c/busses/i2c-virtio.c
>> create mode 100644 include/uapi/linux/virtio_i2c.h
>>
>> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
>> index 05ebf75..0860395 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
> depends on I2C as well ?
No need that. The dependency of I2C is included in the Kconfig in its
parent directory.>
>> + 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 615f35e..b88da08 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
>> +
> Not that it is important but I would have added it towards the end instead
of at
> the top of the file..
I'm OK to add it to the end.>
>> # 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..98c0fcc
>> --- /dev/null
>> +++ b/drivers/i2c/busses/i2c-virtio.c
>> @@ -0,0 +1,289 @@
>> +// SPDX-License-Identifier: GPL-2.0-or-later
>> +/*
>> + * Virtio I2C Bus Driver
>> + *
>> + * The Virtio I2C Specification:
>> + *
https://raw.githubusercontent.com/oasis-tcs/virtio-spec/master/virtio-i2c.tex
>> + *
>> + * Copyright (c) 2021 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>
> I don't think above two are required here..
>
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/platform_device.h>
> same here.
>
>> +#include <linux/wait.h>
> same here.
Will confirm and remove them if they are not required. Thank
you.>> +
> And this blank line as well, since all are standard linux headers.
>> +#include <linux/virtio.h>
>> +#include <linux/virtio_i2c.h>
>> +
>> +/**
>> + * struct virtio_i2c - virtio I2C data
>> + * @vdev: virtio device for this controller
>> + * @completion: completion of virtio I2C message
>> + * @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 i2c_adapter adap;
>> + struct mutex i2c_lock;
> i2c_ is redundant here. "lock" sounds good enough.
OK.>> + struct virtqueue *vq;
>> +};
>> +
>> +/**
>> + * struct virtio_i2c_req - the virtio I2C request structure
>> + * @out_hdr: the OUT header of the virtio I2C message
>> + * @buf: the buffer into which data is read, or from which it's
written
>> + * @in_hdr: the IN header of the virtio I2C message
>> + */
>> +struct virtio_i2c_req {
>> + struct virtio_i2c_out_hdr out_hdr;
>> + u8 *buf;
>> + struct virtio_i2c_in_hdr in_hdr;
>> +};
>> +
>> +static void virtio_i2c_msg_done(struct virtqueue *vq)
>> +{
>> + struct virtio_i2c *vi = vq->vdev->priv;
>> +
>> + complete(&vi->completion);
>> +}
>> +
>> +static int virtio_i2c_send_reqs(struct virtqueue *vq,
>> + struct virtio_i2c_req *reqs,
>> + struct i2c_msg *msgs, int nr)
>> +{
>> + struct scatterlist *sgs[3], out_hdr, msg_buf, in_hdr;
>> + int i, outcnt, incnt, err = 0;
>> + u8 *buf;
>> +
>> + for (i = 0; i < nr; i++) {
>> + if (!msgs[i].len)
>> + break;
>> +
>> + /* Only 7-bit mode supported for this moment. For the address
format,
>> + * Please check the Virtio I2C Specification.
>> + */
> Please use proper comment style.
will fix it.>
> /*
> * Only 7-bit mode supported for now, check Virtio I2C
> * specification for format of "addr" field.
> */
>
>> + reqs[i].out_hdr.addr = cpu_to_le16(msgs[i].addr << 1);
>> +
>> + if (i != nr - 1)
>> + reqs[i].out_hdr.flags |= VIRTIO_I2C_FLAGS_FAIL_NEXT;
> Since flags field hasn't been touched anywhere, directly assigning it
may be
> better instead of |=, it makes it more readable.
OK.>> +
>> + outcnt = incnt = 0;
>> + sg_init_one(&out_hdr, &reqs[i].out_hdr,
sizeof(reqs[i].out_hdr));
>> + sgs[outcnt++] = &out_hdr;
>> +
>> + buf = kzalloc(msgs[i].len, GFP_KERNEL);
>> + if (!buf)
>> + break;
>> +
>> + reqs[i].buf = buf;
>> + sg_init_one(&msg_buf, reqs[i].buf, msgs[i].len);
>> +
>> + if (msgs[i].flags & I2C_M_RD) {
>> + sgs[outcnt + incnt++] = &msg_buf;
>> + } else {
>> + memcpy(reqs[i].buf, msgs[i].buf, msgs[i].len);
>> + sgs[outcnt++] = &msg_buf;
>> + }
>> +
>> + sg_init_one(&in_hdr, &reqs[i].in_hdr,
sizeof(reqs[i].in_hdr));
>> + sgs[outcnt + incnt++] = &in_hdr;
>> +
>> + err = virtqueue_add_sgs(vq, sgs, outcnt, incnt, &reqs[i],
GFP_KERNEL);
>> + if (err < 0) {
>> + pr_err("failed to add msg[%d] to virtqueue.\n", i);
>> + kfree(reqs[i].buf);
>> + reqs[i].buf = NULL;
>> + break;
>> + }
>> + }
>> +
>> + return i;
>> +}
>> +
>> +static int virtio_i2c_complete_reqs(struct virtqueue *vq,
>> + struct virtio_i2c_req *reqs,
>> + struct i2c_msg *msgs, int nr)
>> +{
>> + struct virtio_i2c_req *req;
>> + unsigned int len;
>> + int i;
>> +
>> + for (i = 0; i < nr; i++) {
>> + req = (struct virtio_i2c_req *)virtqueue_get_buf(vq, &len);
> No need of cast here since return type is void *.
Right. Thank you.>
>> + if (!(req && req == &reqs[i])) {
> I find this less readable compared to:
> if (!req || req != &reqs[i]) {
Different people may have different tastes.
Please check Andy's comment in this link.
https://lists.linuxfoundation.org/pipermail/virtualization/2020-September/049933.html
>
>> + pr_err("msg[%d]: addr=0x%x virtqueue error.\n", i,
msgs[i].addr);
>> + break;
>> + }
>> +
>> + if (req->in_hdr.status != VIRTIO_I2C_MSG_OK) {
>> + pr_err("msg[%d]: addr=0x%x backend error.\n", i,
msgs[i].addr);
>> + break;
>> + }
> For all the above errors where you simply break out, you still need to free
the
> memory for buf, right ?
Will try to use reqs[i].buf = msgs[i].buf to avoid
allocation.>> +
>> + if (msgs[i].flags & I2C_M_RD)
>> + memcpy(msgs[i].buf, req->buf, msgs[i].len);
>> +
>> + kfree(req->buf);
>> + req->buf = NULL;
>> + }
>> +
>> + return i;
>> +}
>> +
>> +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_req *reqs;
>> + unsigned long time_left;
>> + int ret, nr;
>> +
>> + reqs = kcalloc(num, sizeof(*reqs), GFP_KERNEL);
>> + if (!reqs)
>> + return -ENOMEM;
>> +
>> + mutex_lock(&vi->i2c_lock);
> I have never worked with i2c stuff earlier, but I don't think you need
a lock
> here. The transactions seem to be serialized by the i2c-core by itself
(look at
> i2c_transfer() in i2c-core-base.c), though there is another exported
version
> __i2c_transfer() but the comment over it says the callers must take adapter
lock
> before calling it.
Lock is needed since no "lock_ops" is registered in this
i2c_adapter.>
>> +
>> + ret = virtio_i2c_send_reqs(vq, reqs, msgs, num);
>> + if (ret == 0)
>> + goto err_unlock_free;
>> +
>> + nr = ret;
>> +
>> + virtqueue_kick(vq);
>> +
>> + time_left = wait_for_completion_timeout(&vi->completion,
adap->timeout);
>> + if (!time_left) {
>> + dev_err(&adap->dev, "virtio i2c backend
timeout.\n");
>> + ret = -ETIMEDOUT;
> You need to free bufs of the requests here as well..
>
>> + goto err_unlock_free;
>> + }
>> +
>> + ret = virtio_i2c_complete_reqs(vq, reqs, msgs, nr);
>> +
>> + reinit_completion(&vi->completion);
>> +
>> +err_unlock_free:
>> + mutex_unlock(&vi->i2c_lock);
>> + kfree(reqs);
>> + return ret;
>> +}
>> +
>> +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,
> Why are we using something that is deprecated here ?
Warn users that the adapter doesn't support classes
anymore.>
>> + .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;
> better add a blank line here.
OK.>> + /* Setup ACPI node for controlled 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");
> You can add module-author as well here.
Sure. I'm glad to do that.>> +MODULE_LICENSE("GPL");
>> diff --git a/include/uapi/linux/virtio_i2c.h
b/include/uapi/linux/virtio_i2c.h
>> new file mode 100644
>> index 0000000..00f4508
>> --- /dev/null
>> +++ b/include/uapi/linux/virtio_i2c.h
>> @@ -0,0 +1,42 @@
>> +/* SPDX-License-Identifier: GPL-2.0-or-later WITH Linux-syscall-note
*/
>> +/*
>> + * Definitions for virtio I2C Adpter
>> + *
>> + * Copyright (c) 2021 Intel Corporation. All rights reserved.
>> + */
>> +
>> +#ifndef _UAPI_LINUX_VIRTIO_I2C_H
>> +#define _UAPI_LINUX_VIRTIO_I2C_H
>> +
>> +#include <linux/types.h>
>> +#include <linux/virtio_ids.h>
>> +#include <linux/virtio_config.h>
> Any file (header or c) should only include what it directly needs and
nothing
> else. And so you should need only types.h here and nothing else.
OK.>> +
>> +/**
>> + * struct virtio_i2c_out_hdr - the virtio I2C message OUT header
>> + * @addr: the controlled device address
>> + * @padding: used to pad to full dword
>> + * @flags: used for feature extensibility
>> + */
>> +struct virtio_i2c_out_hdr {
>> + __le16 addr;
>> + __le16 padding;
>> + __le32 flags;
>> +};
> It might be worth setting __packed for the structures here, even when we
have
> taken care of padding ourselves, for both the structures..
Please check Michael's comment https://lkml.org/lkml/2020/9/3/339.
I agreed to remove "__packed" .>> +
>> +/* The bit 0 of the @virtio_i2c_out_hdr. at flags, used to group the
requests */
>> +#define VIRTIO_I2C_FLAGS_FAIL_NEXT 0x00000001
>> +
> I would define this before the above structure.
OK.>> +/**
>> + * struct virtio_i2c_in_hdr - the virtio I2C message IN header
>> + * @status: the processing result from the backend
>> + */
>> +struct virtio_i2c_in_hdr {
>> + u8 status;
>> +};
>> +
>> +/* The final status written by the device */
>> +#define VIRTIO_I2C_MSG_OK 0
>> +#define VIRTIO_I2C_MSG_ERR 1
>> +
>> +#endif /* _UAPI_LINUX_VIRTIO_I2C_H */
>> diff --git a/include/uapi/linux/virtio_ids.h
b/include/uapi/linux/virtio_ids.h
>> index bc1c062..6ae32db 100644
>> --- a/include/uapi/linux/virtio_ids.h
>> +++ b/include/uapi/linux/virtio_ids.h
>> @@ -54,5 +54,6 @@
>> #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 */
> Thanks for yet another version Jie.
>