I saw your email about wrong version being sent, I already wrote some reviews. Sending them anyway for FWIW :) On 12-03-21, 21:33, Jie Deng wrote: > diff --git a/drivers/i2c/busses/i2c-virtio.c b/drivers/i2c/busses/i2c-virtio.c > new file mode 100644 > index 0000000..bbde8de > --- /dev/null > +++ b/drivers/i2c/busses/i2c-virtio.c > @@ -0,0 +1,287 @@ > +// 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/kernel.h> > +#include <linux/module.h> > +#include <linux/virtio.h> > +#include <linux/virtio_ids.h> > +#include <linux/virtio_config.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 lock; As I said in the previous version (Yes, we were both waiting for Wolfram to answer that), this lock shouldn't be required at all. And since none of us have a use-case at hand where we will have a problem without this lock, we should really skip it. We can always come back and add it if we find an issue somewhere. Until then, better to keep it simple. > + 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; > + uint8_t *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; > + > + 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. > + */ > + reqs[i].out_hdr.addr = cpu_to_le16(msgs[i].addr << 1); > + > + if (i != nr - 1) > + reqs[i].out_hdr.flags = cpu_to_le32(VIRTIO_I2C_FLAGS_FAIL_NEXT); > + > + outcnt = incnt = 0; > + sg_init_one(&out_hdr, &reqs[i].out_hdr, sizeof(reqs[i].out_hdr)); > + sgs[outcnt++] = &out_hdr; > + > + reqs[i].buf = i2c_get_dma_safe_msg_buf(&msgs[i], 1); > + if (!reqs[i].buf) > + break; > + > + sg_init_one(&msg_buf, reqs[i].buf, msgs[i].len); > + > + if (msgs[i].flags & I2C_M_RD) > + sgs[outcnt + incnt++] = &msg_buf; > + else > + 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); > + i2c_put_dma_safe_msg_buf(reqs[i].buf, &msgs[i], false); > + 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, unused; > + int i, j; > + > + for (i = 0; i < nr; i++) { > + req = virtqueue_get_buf(vq, &len); > + if (!(req && req == &reqs[i])) { > + pr_err("msg[%d]: addr=0x%x is out of order.\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; > + } > + > + i2c_put_dma_safe_msg_buf(req->buf, &msgs[i], true); > + } > + > + /* Release unused DMA safe buffer if any */ > + for (j = i; j < nr; j++) > + i2c_put_dma_safe_msg_buf(req->buf, &msgs[j], false); > + > + /* Detach all the used buffers from the vq */ > + while (virtqueue_get_buf(vq, &unused)) > + ; > + > + 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->lock); > + > + ret = virtio_i2c_send_reqs(vq, reqs, msgs, num); > + if (ret == 0) > + goto err_unlock_free; > + > + nr = ret; > + reinit_completion(&vi->completion); > + 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; > + goto err_unlock_free; > + } > + > + ret = virtio_i2c_complete_reqs(vq, reqs, msgs, nr); > + > +err_unlock_free: > + mutex_unlock(&vi->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, What happened to this discussion ? https://lore.kernel.org/lkml/20210305072903.wtw645rukmqr5hx5@vireshk-i7/ > + .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->lock); > + init_completion(&vi->completion); > + > + ret = virtio_i2c_setup_vqs(vi); > + if (ret) > + return ret; > + > + vi->adap = virtio_adapter; This is strange, why are you allocating memory for adapter twice ? Once for virtio_adapter and once for vi->adap ? Either fill the fields directly for v->adap here and remove virtio_adapter or make vi->adap a pointer. > + i2c_set_adapdata(&vi->adap, vi); > + vi->adap.dev.parent = &vdev->dev; > + > + /* 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_AUTHOR("Jie Deng <jie.deng@xxxxxxxxx>"); > +MODULE_AUTHOR("Conghui Chen <conghui.chen@xxxxxxxxx>"); > +MODULE_DESCRIPTION("Virtio i2c bus driver"); > +MODULE_LICENSE("GPL"); -- viresh
