On 2020/9/4 12:06, Jason Wang 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 > > > I guess it should depend on some I2C module here. >The dependency of I2C is included in the Kconfig in its parent directory. So there is nothing special to add here.> >> >> +struct virtio_i2c_msg { >> +??? struct virtio_i2c_hdr hdr; >> +??? char *buf; >> +??? u8 status; > > > Any reason for separating status out of virtio_i2c_hdr? >The status is not from i2c_msg. So I put it out of virtio_i2c_hdr.> >> +}; >> + >> +/** >> + * 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; >> +??? 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 = msg->addr; >> +??? vmsg->hdr.flags = msg->flags; >> +??? vmsg->hdr.len = msg->len; > > > Missing endian conversion? >You are right. Need conversion here.> >> + >> +??? vmsg->buf = kzalloc(vmsg->hdr.len, GFP_KERNEL); >> +??? if (!vmsg->buf) >> +??????? return -ENOMEM; >> + >> +??? sg_init_one(&hdr, &vmsg->hdr, sizeof(struct virtio_i2c_hdr)); >> +??? sgs[outcnt++] = &hdr; >> +??? if (vmsg->hdr.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 virtio_i2c_msg *vmsg_o, *vmsg_i; >> +??? struct virtqueue *vq = vi->vq; >> +??? unsigned long time_left; >> +??? int len, i, ret = 0; >> + >> +??? vmsg_o = kzalloc(sizeof(*vmsg_o), GFP_KERNEL); >> +??? if (!vmsg_o) >> +??????? return -ENOMEM; > > > It looks to me we can avoid the allocation by embedding virtio_i2c_msg > into struct virtio_i2c; >Yeah... That's better. Thanks.> >> + >> +??? mutex_lock(&vi->i2c_lock); >> +??? vmsg_o->buf = NULL; >> +??? for (i = 0; i < num; i++) { >> +??????? ret = virtio_i2c_add_msg(vq, vmsg_o, &msgs[i]); >> +??????? if (ret) { >> +??????????? dev_err(&adap->dev, "failed to add msg[%d] to >> virtqueue.\n", i); >> +??????????? goto err_unlock_free; >> +??????? } >> + >> +??????? 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); >> +??????????? ret = i; >> +??????????? goto err_unlock_free; >> +??????? } >> + >> +??????? vmsg_i = (struct virtio_i2c_msg *)virtqueue_get_buf(vq, &len); >> +??????? if (vmsg_i) { >> +??????????? /* vmsg_i should point to the same address with vmsg_o */ >> +??????????? if (vmsg_i != vmsg_o) { >> +??????????????? dev_err(&adap->dev, "msg[%d]: addr=0x%x virtqueue >> error.\n", >> +??????????????????? i, vmsg_i->hdr.addr); >> +??????????????? ret = i; >> +??????????????? goto err_unlock_free; >> +??????????? } > > > Does this imply in order completion of i2c device?? (E.g what happens > if multiple virtio i2c requests are submitted) > > Btw, this always use a single descriptor once a time which makes me > suspect if a virtqueue(virtio) is really needed. It looks to me we can > utilize the virtqueue by submit the request in a batch. >I'm afraid not all physical devices support batch. I'd like to keep the current design and consider your suggestion as a possible optimization in the future. Thanks.>> >> +} >> + >> +static void virtio_i2c_del_vqs(struct virtio_device *vdev) >> +{ >> +??? vdev->config->reset(vdev); > > > Why need reset here? > > Thanks >I'm following what other virtio drivers do. They reset the devices before they clean up the queues.> >> +??? 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, >> "i2c-msg"); > > > We've in the scope of ic2, so "msg" should be sufficient. > >OK. Will change this name. Thanks.>> +??? return PTR_ERR_OR_ZERO(vi->vq);
On 2020/9/4 ??9:21, Jie Deng wrote:> > On 2020/9/4 12:06, Jason Wang 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 >> >> >> I guess it should depend on some I2C module here. >> > The dependency of I2C is included in the Kconfig in its parent directory. > So there is nothing special to add here.Ok.> > >> >>> >>> +struct virtio_i2c_msg { >>> +??? struct virtio_i2c_hdr hdr; >>> +??? char *buf; >>> +??? u8 status; >> >> >> Any reason for separating status out of virtio_i2c_hdr? >> > The status is not from i2c_msg.You meant ic2_hdr? You embed status in virtio_i2c_msg anyway.> So I put it out of virtio_i2c_hdr.Something like status or response is pretty common in virtio request (e.g net or scsi), if no special reason, it's better to keep it in the hdr.> >> >>> +}; >>> + >>> +/** >>> + * 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; >>> +??? 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 = msg->addr; >>> +??? vmsg->hdr.flags = msg->flags; >>> +??? vmsg->hdr.len = msg->len; >> >> >> Missing endian conversion? >> > You are right. Need conversion here. >> >>> + >>> +??? vmsg->buf = kzalloc(vmsg->hdr.len, GFP_KERNEL); >>> +??? if (!vmsg->buf) >>> +??????? return -ENOMEM; >>> + >>> +??? sg_init_one(&hdr, &vmsg->hdr, sizeof(struct virtio_i2c_hdr)); >>> +??? sgs[outcnt++] = &hdr; >>> +??? if (vmsg->hdr.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 virtio_i2c_msg *vmsg_o, *vmsg_i; >>> +??? struct virtqueue *vq = vi->vq; >>> +??? unsigned long time_left; >>> +??? int len, i, ret = 0; >>> + >>> +??? vmsg_o = kzalloc(sizeof(*vmsg_o), GFP_KERNEL); >>> +??? if (!vmsg_o) >>> +??????? return -ENOMEM; >> >> >> It looks to me we can avoid the allocation by embedding >> virtio_i2c_msg into struct virtio_i2c; >> > Yeah... That's better. Thanks. > > >> >>> + >>> +??? mutex_lock(&vi->i2c_lock); >>> +??? vmsg_o->buf = NULL; >>> +??? for (i = 0; i < num; i++) { >>> +??????? ret = virtio_i2c_add_msg(vq, vmsg_o, &msgs[i]); >>> +??????? if (ret) { >>> +??????????? dev_err(&adap->dev, "failed to add msg[%d] to >>> virtqueue.\n", i); >>> +??????????? goto err_unlock_free; >>> +??????? } >>> + >>> +??????? 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); >>> +??????????? ret = i; >>> +??????????? goto err_unlock_free; >>> +??????? } >>> + >>> +??????? vmsg_i = (struct virtio_i2c_msg *)virtqueue_get_buf(vq, &len); >>> +??????? if (vmsg_i) { >>> +??????????? /* vmsg_i should point to the same address with vmsg_o */ >>> +??????????? if (vmsg_i != vmsg_o) { >>> +??????????????? dev_err(&adap->dev, "msg[%d]: addr=0x%x virtqueue >>> error.\n", >>> +??????????????????? i, vmsg_i->hdr.addr); >>> +??????????????? ret = i; >>> +??????????????? goto err_unlock_free; >>> +??????????? } >> >> >> Does this imply in order completion of i2c device?? (E.g what happens >> if multiple virtio i2c requests are submitted) >> >> Btw, this always use a single descriptor once a time which makes me >> suspect if a virtqueue(virtio) is really needed. It looks to me we >> can utilize the virtqueue by submit the request in a batch. >> > I'm afraid not all physical devices support batch.Yes but I think I meant for the virtio device not the physical one. It's impossible to forbid batching if you have a queue anyway ...> I'd like to keep the current design and consider > your suggestion as a possible optimization in the future. > > Thanks. > > >>> >>> +} >>> + >>> +static void virtio_i2c_del_vqs(struct virtio_device *vdev) >>> +{ >>> +??? vdev->config->reset(vdev); >> >> >> Why need reset here? >> >> Thanks >> > I'm following what other virtio drivers do. > They reset the devices before they clean up the queues.You're ring. Thanks> > >> >>> +??? 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, >>> "i2c-msg"); >> >> >> We've in the scope of ic2, so "msg" should be sufficient. >> >> > OK. Will change this name. Thanks. > > >>> +??? return PTR_ERR_OR_ZERO(vi->vq); >
On 2020/9/7 13:40, Jason Wang wrote:> >> >> >>> >>>> >>>> +struct virtio_i2c_msg { >>>> +??? struct virtio_i2c_hdr hdr; >>>> +??? char *buf; >>>> +??? u8 status; >>> >>> >>> Any reason for separating status out of virtio_i2c_hdr? >>> >> The status is not from i2c_msg. > > > You meant ic2_hdr? You embed status in virtio_i2c_msg anyway. > >The "i2c_msg" structure defined in i2c.h.>> So I put it out of virtio_i2c_hdr. > > > Something like status or response is pretty common in virtio request > (e.g net or scsi), if no special reason, it's better to keep it in the > hdr. >Mainly based on IN or OUT. The addr, flags and len are from "i2c_msg". They are put in one structure as an OUT**scatterlist. The buf can be an OUT**or an IN scatterlist depending on write or read. The status is a result from the backend? which is defined as an IN scatterlis.>-------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.linuxfoundation.org/pipermail/virtualization/attachments/20200908/2d7a2f2e/attachment-0001.html>