i2c: virtio: add a virtio i2c frontend driver
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. The device specification can be found on https://lists.oasis-open.org/archives/virtio-comment/202101/msg00008.html. By following the specification, people may implement different backend drivers to emulate different controllers according to their needs. 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: Viresh Kumar <viresh.kumar@linaro.org> Tested-by: Viresh Kumar <viresh.kumar@linaro.org> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Wolfram Sang <wsa@kernel.org>
This commit is contained in:
Jie Deng
Wolfram Sang
parent
f9b459c2ba
commit
3cfc883804
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@ -19708,6 +19708,15 @@ S: Maintained
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F: include/uapi/linux/virtio_snd.h
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F: sound/virtio/*
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VIRTIO I2C DRIVER
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M: Jie Deng <jie.deng@intel.com>
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M: Viresh Kumar <viresh.kumar@linaro.org>
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L: linux-i2c@vger.kernel.org
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L: virtualization@lists.linux-foundation.org
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S: Maintained
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F: drivers/i2c/busses/i2c-virtio.c
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F: include/uapi/linux/virtio_i2c.h
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VIRTUAL BOX GUEST DEVICE DRIVER
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M: Hans de Goede <hdegoede@redhat.com>
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M: Arnd Bergmann <arnd@arndb.de>
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@ -1393,4 +1393,15 @@ config I2C_FSI
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This driver can also be built as a module. If so, the module will be
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called as i2c-fsi.
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config I2C_VIRTIO
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tristate "Virtio I2C Adapter"
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select VIRTIO
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help
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If you say yes to this option, support will be included for the virtio
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I2C adapter driver. The hardware can be emulated by any device model
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software according to the virtio protocol.
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This driver can also be built as a module. If so, the module
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will be called i2c-virtio.
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endmenu
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@ -145,5 +145,6 @@ obj-$(CONFIG_I2C_SIBYTE) += i2c-sibyte.o
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obj-$(CONFIG_I2C_XGENE_SLIMPRO) += i2c-xgene-slimpro.o
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obj-$(CONFIG_SCx200_ACB) += scx200_acb.o
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obj-$(CONFIG_I2C_FSI) += i2c-fsi.o
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obj-$(CONFIG_I2C_VIRTIO) += i2c-virtio.o
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ccflags-$(CONFIG_I2C_DEBUG_BUS) := -DDEBUG
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@ -0,0 +1,290 @@
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// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Virtio I2C Bus Driver
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*
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* The Virtio I2C Specification:
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* https://raw.githubusercontent.com/oasis-tcs/virtio-spec/master/virtio-i2c.tex
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*
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* Copyright (c) 2021 Intel Corporation. All rights reserved.
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*/
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#include <linux/acpi.h>
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#include <linux/completion.h>
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#include <linux/err.h>
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#include <linux/i2c.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/virtio.h>
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#include <linux/virtio_ids.h>
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#include <linux/virtio_config.h>
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#include <linux/virtio_i2c.h>
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/**
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* struct virtio_i2c - virtio I2C data
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* @vdev: virtio device for this controller
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* @completion: completion of virtio I2C message
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* @adap: I2C adapter for this controller
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* @vq: the virtio virtqueue for communication
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*/
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struct virtio_i2c {
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struct virtio_device *vdev;
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struct completion completion;
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struct i2c_adapter adap;
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struct virtqueue *vq;
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};
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/**
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* struct virtio_i2c_req - the virtio I2C request structure
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* @out_hdr: the OUT header of the virtio I2C message
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* @buf: the buffer into which data is read, or from which it's written
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* @in_hdr: the IN header of the virtio I2C message
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*/
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struct virtio_i2c_req {
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struct virtio_i2c_out_hdr out_hdr ____cacheline_aligned;
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uint8_t *buf ____cacheline_aligned;
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struct virtio_i2c_in_hdr in_hdr ____cacheline_aligned;
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};
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static void virtio_i2c_msg_done(struct virtqueue *vq)
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{
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struct virtio_i2c *vi = vq->vdev->priv;
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complete(&vi->completion);
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}
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static int virtio_i2c_prepare_reqs(struct virtqueue *vq,
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struct virtio_i2c_req *reqs,
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struct i2c_msg *msgs, int num)
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{
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struct scatterlist *sgs[3], out_hdr, msg_buf, in_hdr;
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int i;
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for (i = 0; i < num; i++) {
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int outcnt = 0, incnt = 0;
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/*
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* We don't support 0 length messages and so filter out
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* 0 length transfers by using i2c_adapter_quirks.
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*/
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if (!msgs[i].len)
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break;
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/*
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* Only 7-bit mode supported for this moment. For the address
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* format, Please check the Virtio I2C Specification.
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*/
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reqs[i].out_hdr.addr = cpu_to_le16(msgs[i].addr << 1);
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if (i != num - 1)
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reqs[i].out_hdr.flags = cpu_to_le32(VIRTIO_I2C_FLAGS_FAIL_NEXT);
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sg_init_one(&out_hdr, &reqs[i].out_hdr, sizeof(reqs[i].out_hdr));
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sgs[outcnt++] = &out_hdr;
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reqs[i].buf = i2c_get_dma_safe_msg_buf(&msgs[i], 1);
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if (!reqs[i].buf)
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break;
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sg_init_one(&msg_buf, reqs[i].buf, msgs[i].len);
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if (msgs[i].flags & I2C_M_RD)
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sgs[outcnt + incnt++] = &msg_buf;
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else
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sgs[outcnt++] = &msg_buf;
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sg_init_one(&in_hdr, &reqs[i].in_hdr, sizeof(reqs[i].in_hdr));
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sgs[outcnt + incnt++] = &in_hdr;
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if (virtqueue_add_sgs(vq, sgs, outcnt, incnt, &reqs[i], GFP_KERNEL)) {
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i2c_put_dma_safe_msg_buf(reqs[i].buf, &msgs[i], false);
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break;
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}
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}
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return i;
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}
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static int virtio_i2c_complete_reqs(struct virtqueue *vq,
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struct virtio_i2c_req *reqs,
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struct i2c_msg *msgs, int num,
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bool timedout)
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{
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struct virtio_i2c_req *req;
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bool failed = timedout;
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unsigned int len;
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int i, j = 0;
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for (i = 0; i < num; i++) {
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/* Detach the ith request from the vq */
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req = virtqueue_get_buf(vq, &len);
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/*
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* Condition req == &reqs[i] should always meet since we have
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* total num requests in the vq. reqs[i] can never be NULL here.
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*/
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if (!failed && (WARN_ON(req != &reqs[i]) ||
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req->in_hdr.status != VIRTIO_I2C_MSG_OK))
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failed = true;
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i2c_put_dma_safe_msg_buf(reqs[i].buf, &msgs[i], !failed);
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if (!failed)
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j++;
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}
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return timedout ? -ETIMEDOUT : j;
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}
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static int virtio_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
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int num)
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{
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struct virtio_i2c *vi = i2c_get_adapdata(adap);
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struct virtqueue *vq = vi->vq;
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struct virtio_i2c_req *reqs;
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unsigned long time_left;
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int count;
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reqs = kcalloc(num, sizeof(*reqs), GFP_KERNEL);
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if (!reqs)
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return -ENOMEM;
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count = virtio_i2c_prepare_reqs(vq, reqs, msgs, num);
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if (!count)
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goto err_free;
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/*
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* For the case where count < num, i.e. we weren't able to queue all the
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* msgs, ideally we should abort right away and return early, but some
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* of the messages are already sent to the remote I2C controller and the
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* virtqueue will be left in undefined state in that case. We kick the
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* remote here to clear the virtqueue, so we can try another set of
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* messages later on.
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*/
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reinit_completion(&vi->completion);
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virtqueue_kick(vq);
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time_left = wait_for_completion_timeout(&vi->completion, adap->timeout);
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if (!time_left)
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dev_err(&adap->dev, "virtio i2c backend timeout.\n");
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count = virtio_i2c_complete_reqs(vq, reqs, msgs, count, !time_left);
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err_free:
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kfree(reqs);
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return count;
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}
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static void virtio_i2c_del_vqs(struct virtio_device *vdev)
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{
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vdev->config->reset(vdev);
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vdev->config->del_vqs(vdev);
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}
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static int virtio_i2c_setup_vqs(struct virtio_i2c *vi)
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{
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struct virtio_device *vdev = vi->vdev;
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vi->vq = virtio_find_single_vq(vdev, virtio_i2c_msg_done, "msg");
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return PTR_ERR_OR_ZERO(vi->vq);
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}
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static u32 virtio_i2c_func(struct i2c_adapter *adap)
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{
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return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);
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}
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static struct i2c_algorithm virtio_algorithm = {
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.master_xfer = virtio_i2c_xfer,
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.functionality = virtio_i2c_func,
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};
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static const struct i2c_adapter_quirks virtio_i2c_quirks = {
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.flags = I2C_AQ_NO_ZERO_LEN,
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};
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static int virtio_i2c_probe(struct virtio_device *vdev)
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{
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struct virtio_i2c *vi;
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int ret;
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vi = devm_kzalloc(&vdev->dev, sizeof(*vi), GFP_KERNEL);
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if (!vi)
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return -ENOMEM;
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vdev->priv = vi;
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vi->vdev = vdev;
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init_completion(&vi->completion);
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ret = virtio_i2c_setup_vqs(vi);
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if (ret)
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return ret;
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vi->adap.owner = THIS_MODULE;
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snprintf(vi->adap.name, sizeof(vi->adap.name),
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"i2c_virtio at virtio bus %d", vdev->index);
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vi->adap.algo = &virtio_algorithm;
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vi->adap.quirks = &virtio_i2c_quirks;
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vi->adap.dev.parent = &vdev->dev;
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vi->adap.dev.of_node = vdev->dev.of_node;
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i2c_set_adapdata(&vi->adap, vi);
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/*
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* Setup ACPI node for controlled devices which will be probed through
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* ACPI.
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*/
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ACPI_COMPANION_SET(&vi->adap.dev, ACPI_COMPANION(vdev->dev.parent));
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ret = i2c_add_adapter(&vi->adap);
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if (ret)
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virtio_i2c_del_vqs(vdev);
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return ret;
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}
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static void virtio_i2c_remove(struct virtio_device *vdev)
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{
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struct virtio_i2c *vi = vdev->priv;
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i2c_del_adapter(&vi->adap);
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virtio_i2c_del_vqs(vdev);
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}
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static struct virtio_device_id id_table[] = {
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{ VIRTIO_ID_I2C_ADAPTER, VIRTIO_DEV_ANY_ID },
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{}
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};
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MODULE_DEVICE_TABLE(virtio, id_table);
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#ifdef CONFIG_PM_SLEEP
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static int virtio_i2c_freeze(struct virtio_device *vdev)
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{
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virtio_i2c_del_vqs(vdev);
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return 0;
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}
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static int virtio_i2c_restore(struct virtio_device *vdev)
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{
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return virtio_i2c_setup_vqs(vdev->priv);
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}
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#endif
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static struct virtio_driver virtio_i2c_driver = {
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.id_table = id_table,
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.probe = virtio_i2c_probe,
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.remove = virtio_i2c_remove,
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.driver = {
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.name = "i2c_virtio",
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},
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#ifdef CONFIG_PM_SLEEP
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.freeze = virtio_i2c_freeze,
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.restore = virtio_i2c_restore,
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#endif
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};
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module_virtio_driver(virtio_i2c_driver);
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MODULE_AUTHOR("Jie Deng <jie.deng@intel.com>");
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MODULE_AUTHOR("Conghui Chen <conghui.chen@intel.com>");
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MODULE_DESCRIPTION("Virtio i2c bus driver");
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MODULE_LICENSE("GPL");
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@ -0,0 +1,41 @@
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/* SPDX-License-Identifier: GPL-2.0-or-later WITH Linux-syscall-note */
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/*
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* Definitions for virtio I2C Adpter
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*
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* Copyright (c) 2021 Intel Corporation. All rights reserved.
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*/
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#ifndef _UAPI_LINUX_VIRTIO_I2C_H
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#define _UAPI_LINUX_VIRTIO_I2C_H
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#include <linux/const.h>
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#include <linux/types.h>
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/* The bit 0 of the @virtio_i2c_out_hdr.@flags, used to group the requests */
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#define VIRTIO_I2C_FLAGS_FAIL_NEXT _BITUL(0)
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/**
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* struct virtio_i2c_out_hdr - the virtio I2C message OUT header
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* @addr: the controlled device address
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* @padding: used to pad to full dword
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* @flags: used for feature extensibility
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*/
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struct virtio_i2c_out_hdr {
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__le16 addr;
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__le16 padding;
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__le32 flags;
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};
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/**
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* struct virtio_i2c_in_hdr - the virtio I2C message IN header
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* @status: the processing result from the backend
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*/
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struct virtio_i2c_in_hdr {
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__u8 status;
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};
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/* The final status written by the device */
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#define VIRTIO_I2C_MSG_OK 0
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#define VIRTIO_I2C_MSG_ERR 1
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#endif /* _UAPI_LINUX_VIRTIO_I2C_H */
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@ -55,6 +55,7 @@
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#define VIRTIO_ID_FS 26 /* virtio filesystem */
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#define VIRTIO_ID_PMEM 27 /* virtio pmem */
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#define VIRTIO_ID_MAC80211_HWSIM 29 /* virtio mac80211-hwsim */
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#define VIRTIO_ID_I2C_ADAPTER 34 /* virtio i2c adapter */
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#define VIRTIO_ID_BT 40 /* virtio bluetooth */
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/*
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