On 22-03-21, 21:35, 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..316986e
> --- /dev/null
> +++ b/drivers/i2c/busses/i2c-virtio.c
> @@ -0,0 +1,286 @@
> +// 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
Name mismatch here.
> + * @vq: the virtio virtqueue for communication
> + */
> +struct virtio_i2c {
> + struct virtio_device *vdev;
> + struct completion completion;
> + struct i2c_adapter adap;
> + struct mutex lock;
> + struct virtqueue *vq;
> +};
> +static int virtio_i2c_complete_reqs(struct virtqueue *vq,
> + struct virtio_i2c_req *reqs,
> + struct i2c_msg *msgs, int nr,
> + bool timeout)
> +{
> + struct virtio_i2c_req *req;
> + bool err_found = false;
> + unsigned int len;
> + int i, j = 0;
> +
> + for (i = 0; i < nr; i++) {
> + /* Detach the ith request from the vq */
> + req = virtqueue_get_buf(vq, &len);
> +
> + if (timeout || err_found) {
> + i2c_put_dma_safe_msg_buf(reqs[i].buf, &msgs[i], false);
> + continue;
> + }
> +
> + /*
> + * Condition (req && req == &reqs[i]) should always meet since
> + * we have total nr requests in the vq.
> + */
> + if (WARN_ON(!(req && req == &reqs[i])) ||
> + (req->in_hdr.status != VIRTIO_I2C_MSG_OK)) {
> + err_found = true;
> + i2c_put_dma_safe_msg_buf(reqs[i].buf, &msgs[i], false);
> + continue;
> + }
> +
> + i2c_put_dma_safe_msg_buf(reqs[i].buf, &msgs[i], true);
> + ++j;
> + }
I think you can simplify the code like this here:
bool err_found = timeout;
for (i = 0; i < nr; i++) {
/* Detach the ith request from the vq */
req = virtqueue_get_buf(vq, &len);
/*
* Condition (req && req == &reqs[i]) should always meet since
* we have total nr requests in the vq.
*/
if (!err_found &&
(WARN_ON(!(req && req == &reqs[i])) ||
(req->in_hdr.status != VIRTIO_I2C_MSG_OK))) {
err_found = true;
continue;
}
i2c_put_dma_safe_msg_buf(reqs[i].buf, &msgs[i], err_found);
if (!err_found)
++j;
> +
> + return (timeout ? -ETIMEDOUT : j);
> +}
> +
> +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 = virtio_i2c_complete_reqs(vq, reqs, msgs, nr, true);
> + goto err_unlock_free;
> + }
> +
> + ret = virtio_i2c_complete_reqs(vq, reqs, msgs, nr, false);
And this can be optimized as well:
time_left = wait_for_completion_timeout(&vi->completion, adap->timeout);
if (!time_left)
dev_err(&adap->dev, "virtio i2c backend timeout.\n");
ret = virtio_i2c_complete_reqs(vq, reqs, msgs, nr, !time_left);
--
viresh
