On Mon, Oct 12, 2020 at 09:55:55AM +0800, Jie Deng wrote: > 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. > > This driver communicates with the backend driver through a > virtio I2C message structure which includes following parts: > > - Header: i2c_msg addr, flags, len. > - Data buffer: the pointer to the I2C msg data. > - Status: the processing result from the backend. > > People may implement different backend drivers to emulate > different controllers according to their needs. A backend > example can be found in the device model of the open source > project ACRN. For more information, please refer to > https://projectacrn.org. > > The virtio device ID 34 is used for this I2C adpter since IDs > before 34 have been reserved by other virtio devices. > > Co-developed-by: Conghui Chen <conghui.chen@xxxxxxxxx> > Signed-off-by: Conghui Chen <conghui.chen@xxxxxxxxx> > Signed-off-by: Jie Deng <jie.deng@xxxxxxxxx> > Reviewed-by: Shuo Liu <shuo.a.liu@xxxxxxxxx> > Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> I assume this will be updated once the specification is acked by the virtio tc. Holding off on this one for now since we know there will be host/guest ABI changes. > --- > The device ID request: > https://github.com/oasis-tcs/virtio-spec/issues/85 > > The specification: > https://lists.oasis-open.org/archives/virtio-comment/202009/msg00021.html > > Changes in v4: > - Use (!(vmsg && vmsg == &vi->vmsg)) instead of ((!vmsg) || (vmsg != &vi->vmsg)) > > Changes in v3: > - Move the interface into uAPI according to Jason. > - Fix issues reported by Dan Carpenter. > - Fix typo reported by Randy. > > Changes in v2: > - Addressed comments received from Michael, Andy and Jason. > > drivers/i2c/busses/Kconfig | 11 ++ > drivers/i2c/busses/Makefile | 3 + > drivers/i2c/busses/i2c-virtio.c | 256 ++++++++++++++++++++++++++++++++++++++++ > include/uapi/linux/virtio_i2c.h | 31 +++++ > include/uapi/linux/virtio_ids.h | 1 + > 5 files changed, 302 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 293e7a0..f2f6543 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 > + 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 19aff0e..821acfa 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 > + > # 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..36d8c68 > --- /dev/null > +++ b/drivers/i2c/busses/i2c-virtio.c > @@ -0,0 +1,256 @@ > +// SPDX-License-Identifier: GPL-2.0-or-later > +/* > + * Virtio I2C Bus Driver > + * > + * Copyright (c) 2020 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> > +#include <linux/kernel.h> > +#include <linux/module.h> > +#include <linux/platform_device.h> > +#include <linux/wait.h> > + > +#include <linux/virtio.h> > +#include <linux/virtio_i2c.h> > + > +/** > + * struct virtio_i2c_msg - the virtio I2C message structure > + * @hdr: the virtio I2C message header > + * @buf: virtio I2C message data buffer > + * @status: the processing result from the backend > + */ > +struct virtio_i2c_msg { > + struct virtio_i2c_hdr hdr; > + u8 *buf; > + u8 status; > +}; > + > +/** > + * struct virtio_i2c - virtio I2C data > + * @vdev: virtio device for this controller > + * @completion: completion of virtio I2C message > + * @vmsg: the virtio I2C message for communication > + * @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 virtio_i2c_msg vmsg; > + 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 = cpu_to_le16(msg->addr); > + vmsg->hdr.flags = cpu_to_le16(msg->flags); > + vmsg->hdr.len = cpu_to_le16(msg->len); > + > + vmsg->buf = kzalloc(msg->len, GFP_KERNEL); > + if (!vmsg->buf) > + return -ENOMEM; > + > + sg_init_one(&hdr, &vmsg->hdr, sizeof(struct virtio_i2c_hdr)); > + sgs[outcnt++] = &hdr; > + if (msg->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 virtqueue *vq = vi->vq; > + struct virtio_i2c_msg *vmsg; > + unsigned long time_left; > + int len, i, ret = 0; > + > + mutex_lock(&vi->i2c_lock); > + vmsg = &vi->vmsg; > + vmsg->buf = NULL; > + > + for (i = 0; i < num; i++) { > + ret = virtio_i2c_add_msg(vq, vmsg, &msgs[i]); > + if (ret) { > + dev_err(&adap->dev, "failed to add msg[%d] to virtqueue.\n", i); > + break; > + } > + > + 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); > + break; > + } > + > + vmsg = (struct virtio_i2c_msg *)virtqueue_get_buf(vq, &len); > + /* vmsg should point to the same address with &vi->vmsg */ > + if (!(vmsg && vmsg == &vi->vmsg)) { > + dev_err(&adap->dev, "msg[%d]: addr=0x%x virtqueue error.\n", > + i, msgs[i].addr); > + break; > + } > + > + if (vmsg->status != VIRTIO_I2C_MSG_OK) { > + dev_err(&adap->dev, "msg[%d]: addr=0x%x error=%d.\n", > + i, msgs[i].addr, vmsg->status); > + break; > + } > + > + if ((msgs[i].flags & I2C_M_RD) && msgs[i].len) > + memcpy(msgs[i].buf, vmsg->buf, msgs[i].len); > + > + kfree(vmsg->buf); > + vmsg->buf = NULL; > + > + reinit_completion(&vi->completion); > + } > + > + mutex_unlock(&vi->i2c_lock); > + kfree(vi->vmsg.buf); > + vi->vmsg.buf = NULL; > + return ((ret < 0) ? ret : i); > +} > + > +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, > + .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; > + /* Setup ACPI node for slave 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"); > +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..7413e45 > --- /dev/null > +++ b/include/uapi/linux/virtio_i2c.h > @@ -0,0 +1,31 @@ > +/* SPDX-License-Identifier: GPL-2.0-or-later OR BSD-3-Clause */ > +/* > + * Definitions for virtio I2C Adpter > + * > + * Copyright (c) 2020 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> > + > +/** > + * struct virtio_i2c_hdr - the virtio I2C message header structure > + * @addr: i2c_msg addr, the slave address > + * @flags: i2c_msg flags > + * @len: i2c_msg len > + */ > +struct virtio_i2c_hdr { > + __le16 addr; > + __le16 flags; > + __le16 len; > +}; > + > +/* 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 b052355..398ef2d 100644 > --- a/include/uapi/linux/virtio_ids.h > +++ b/include/uapi/linux/virtio_ids.h > @@ -48,5 +48,6 @@ > #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 */ > -- > 2.7.4
