| Message ID | 0efc2605c8c06b4b1bf68cbad5536c4a900dc019.1599110284.git.jie.deng@intel.com |
|---|---|
| State | New |
| Headers | show |
| Series | i2c: virtio: add a virtio i2c frontend driver | expand |
On 2020/9/3 14:12, Jason Wang wrote: > > On 2020/9/3 下午1:34, 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. > > > May I know the reason why don't you use i2c or virtio directly? > We don't want to add virtio drivers for every I2C devices in the guests. This bus driver is designed to provide a way to flexibly expose the physical I2C slave devices to the guest without adding or changing the drivers of the I2C slave devices in the guest OS. > >> >> The virtio device ID 34 is used for this I2C adpter since IDs >> before 34 have been reserved by other virtio devices. > > > Is there a link to the spec patch? > > Thanks > I haven't submitted the patch to reserve the ID in spec yet. I write the ID here because I want to see your opinions first. Thanks
On Thu, Sep 03, 2020 at 01:34:45PM +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. Please reserve the ID with the virtio tc so no one conflicts. > 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: Shuo Liu <shuo.a.liu@intel.com> > Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > --- > drivers/i2c/busses/Kconfig | 11 ++ > drivers/i2c/busses/Makefile | 3 + > drivers/i2c/busses/i2c-virtio.c | 276 ++++++++++++++++++++++++++++++++++++++++ > include/uapi/linux/virtio_ids.h | 1 + > 4 files changed, 291 insertions(+) > create mode 100644 drivers/i2c/busses/i2c-virtio.c > > 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 > + 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..47f9fd1 > --- /dev/null > +++ b/drivers/i2c/busses/i2c-virtio.c > @@ -0,0 +1,276 @@ > +// 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_ids.h> > +#include <linux/virtio_config.h> > + > +#define VIRTIO_I2C_MSG_OK 0 > +#define VIRTIO_I2C_MSG_ERR 1 > + > +/** > + * 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 { > + __virtio16 addr; > + __virtio16 flags; > + __virtio16 len; > +} __packed; virtio16 is for legacy devices, modern ones should be __le. and we don't really need to pack it I think. > + > +/** > + * 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; > + char *buf; > + u8 status; > +}; > + > +/** > + * 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; > + > + 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; > + > + 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; > + } > + if (vmsg_i->status != VIRTIO_I2C_MSG_OK) { > + dev_err(&adap->dev, "msg[%d]: addr=0x%x error=%d.\n", > + i, vmsg_i->hdr.addr, vmsg_i->status); > + ret = i; > + goto err_unlock_free; > + } > + if ((vmsg_i->hdr.flags & I2C_M_RD) && vmsg_i->hdr.len) > + memcpy(msgs[i].buf, vmsg_i->buf, vmsg_i->hdr.len); > + > + kfree(vmsg_i->buf); > + vmsg_i->buf = NULL; > + } > + reinit_completion(&vi->completion); > + } > + if (i == num) > + ret = num; > + > +err_unlock_free: > + mutex_unlock(&vi->i2c_lock); > + kfree(vmsg_o->buf); > + kfree(vmsg_o); > + 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, "i2c-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) { > + dev_err(&vdev->dev, "failed to add virtio-i2c adapter.\n"); > + virtio_i2c_del_vqs(vdev); > + } > + > + 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_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
On Thu, Sep 03, 2020 at 01:34:45PM +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. Seems it's slightly different version to what I have reviewed internally. My comments below. (I admit that some of them maybe new) ... > +/** > + * 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 { > + __virtio16 addr; > + __virtio16 flags; > + __virtio16 len; > +} __packed; As Misha noticed and somewhere I saw 0-day reports these should be carefully taken care of. ... > +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; > + > + 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; 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); > + ret = i; > + goto err_unlock_free; break; And so on. > + } > + > + 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; > + } > + if (vmsg_i->status != VIRTIO_I2C_MSG_OK) { > + dev_err(&adap->dev, "msg[%d]: addr=0x%x error=%d.\n", > + i, vmsg_i->hdr.addr, vmsg_i->status); > + ret = i; > + goto err_unlock_free; > + } > + if ((vmsg_i->hdr.flags & I2C_M_RD) && vmsg_i->hdr.len) > + memcpy(msgs[i].buf, vmsg_i->buf, vmsg_i->hdr.len); > + > + kfree(vmsg_i->buf); > + vmsg_i->buf = NULL; > + } > + reinit_completion(&vi->completion); > + } > + if (i == num) > + ret = num; And this conditional seems a dup of the for-loop successfully iterating over entire queue. > +err_unlock_free: Redundant. > + mutex_unlock(&vi->i2c_lock); > + kfree(vmsg_o->buf); > + kfree(vmsg_o); > + return ret; > +} ... > + vi->adap.timeout = HZ / 10; + Blank line. > + ret = i2c_add_adapter(&vi->adap); > + if (ret) { > + dev_err(&vdev->dev, "failed to add virtio-i2c adapter.\n"); > + virtio_i2c_del_vqs(vdev); Usually we do clean up followed by message. > + } > + > + return ret;
On 2020/9/3 下午1:34, 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@intel.com> > Signed-off-by: Conghui Chen <conghui.chen@intel.com> > Signed-off-by: Jie Deng <jie.deng@intel.com> > Reviewed-by: Shuo Liu <shuo.a.liu@intel.com> > Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > --- > drivers/i2c/busses/Kconfig | 11 ++ > drivers/i2c/busses/Makefile | 3 + > drivers/i2c/busses/i2c-virtio.c | 276 ++++++++++++++++++++++++++++++++++++++++ > include/uapi/linux/virtio_ids.h | 1 + > 4 files changed, 291 insertions(+) > create mode 100644 drivers/i2c/busses/i2c-virtio.c > > 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. > + 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..47f9fd1 > --- /dev/null > +++ b/drivers/i2c/busses/i2c-virtio.c > @@ -0,0 +1,276 @@ > +// 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_ids.h> > +#include <linux/virtio_config.h> > + > +#define VIRTIO_I2C_MSG_OK 0 > +#define VIRTIO_I2C_MSG_ERR 1 > + > +/** > + * 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 { > + __virtio16 addr; > + __virtio16 flags; > + __virtio16 len; > +} __packed; > + > +/** > + * 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; > + char *buf; > + u8 status; Any reason for separating status 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? > + > + 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; > + > + 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. > + if (vmsg_i->status != VIRTIO_I2C_MSG_OK) { > + dev_err(&adap->dev, "msg[%d]: addr=0x%x error=%d.\n", > + i, vmsg_i->hdr.addr, vmsg_i->status); > + ret = i; > + goto err_unlock_free; > + } > + if ((vmsg_i->hdr.flags & I2C_M_RD) && vmsg_i->hdr.len) > + memcpy(msgs[i].buf, vmsg_i->buf, vmsg_i->hdr.len); > + > + kfree(vmsg_i->buf); > + vmsg_i->buf = NULL; > + } > + reinit_completion(&vi->completion); > + } > + if (i == num) > + ret = num; > + > +err_unlock_free: > + mutex_unlock(&vi->i2c_lock); > + kfree(vmsg_o->buf); > + kfree(vmsg_o); > + return ret; > +} > + > +static void virtio_i2c_del_vqs(struct virtio_device *vdev) > +{ > + vdev->config->reset(vdev); Why need reset here? 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. > + 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) { > + dev_err(&vdev->dev, "failed to add virtio-i2c adapter.\n"); > + virtio_i2c_del_vqs(vdev); > + } > + > + 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_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 */
On 2020/9/3 18:20, Andy Shevchenko wrote: > On Thu, Sep 03, 2020 at 01:34:45PM +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. > Seems it's slightly different version to what I have reviewed internally. > My comments below. (I admit that some of them maybe new) > > ... Yeah... Some new devices have been added into the virtio spec during these days. >> +/** >> + * 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 { >> + __virtio16 addr; >> + __virtio16 flags; >> + __virtio16 len; >> +} __packed; > As Misha noticed and somewhere I saw 0-day reports these should be carefully > taken care of. > > ... Sure. Will fix these. >> +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; >> + >> + 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; > break; OK. >> + } >> + >> + 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; > break; > > And so on. OK. >> + } >> + >> + 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; >> + } >> + if (vmsg_i->status != VIRTIO_I2C_MSG_OK) { >> + dev_err(&adap->dev, "msg[%d]: addr=0x%x error=%d.\n", >> + i, vmsg_i->hdr.addr, vmsg_i->status); >> + ret = i; >> + goto err_unlock_free; >> + } >> + if ((vmsg_i->hdr.flags & I2C_M_RD) && vmsg_i->hdr.len) >> + memcpy(msgs[i].buf, vmsg_i->buf, vmsg_i->hdr.len); >> + >> + kfree(vmsg_i->buf); >> + vmsg_i->buf = NULL; >> + } >> + reinit_completion(&vi->completion); >> + } >> + if (i == num) >> + ret = num; > And this conditional seems a dup of the for-loop successfully iterating over > entire queue. You are right. We may save several lines of code by using "Return (ret<0) ? ret : i" at the end. >> +err_unlock_free: > Redundant. OK. >> + mutex_unlock(&vi->i2c_lock); >> + kfree(vmsg_o->buf); >> + kfree(vmsg_o); >> + return ret; >> +} > ... > >> + vi->adap.timeout = HZ / 10; > + Blank line. OK. >> + ret = i2c_add_adapter(&vi->adap); >> + if (ret) { >> + dev_err(&vdev->dev, "failed to add virtio-i2c adapter.\n"); >> + virtio_i2c_del_vqs(vdev); > Usually we do clean up followed by message. I will change the order. Thank you. >> + } >> + >> + return ret; >
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 2020/9/3 下午1:34, Jie Deng wrote: > --- 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..47f9fd1 > --- /dev/null > +++ b/drivers/i2c/busses/i2c-virtio.c > @@ -0,0 +1,276 @@ > +// 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_ids.h> > +#include <linux/virtio_config.h> > + > +#define VIRTIO_I2C_MSG_OK 0 > +#define VIRTIO_I2C_MSG_ERR 1 > + > +/** > + * 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 { > + __virtio16 addr; > + __virtio16 flags; > + __virtio16 len; > +} __packed; Btw, this part should belong to uAPI, and you need to define the status in uAPI. Thanks
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 + 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..47f9fd1 --- /dev/null +++ b/drivers/i2c/busses/i2c-virtio.c @@ -0,0 +1,276 @@ +// 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_ids.h> +#include <linux/virtio_config.h> + +#define VIRTIO_I2C_MSG_OK 0 +#define VIRTIO_I2C_MSG_ERR 1 + +/** + * 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 { + __virtio16 addr; + __virtio16 flags; + __virtio16 len; +} __packed; + +/** + * 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; + char *buf; + u8 status; +}; + +/** + * 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; + + 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; + + 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; + } + if (vmsg_i->status != VIRTIO_I2C_MSG_OK) { + dev_err(&adap->dev, "msg[%d]: addr=0x%x error=%d.\n", + i, vmsg_i->hdr.addr, vmsg_i->status); + ret = i; + goto err_unlock_free; + } + if ((vmsg_i->hdr.flags & I2C_M_RD) && vmsg_i->hdr.len) + memcpy(msgs[i].buf, vmsg_i->buf, vmsg_i->hdr.len); + + kfree(vmsg_i->buf); + vmsg_i->buf = NULL; + } + reinit_completion(&vi->completion); + } + if (i == num) + ret = num; + +err_unlock_free: + mutex_unlock(&vi->i2c_lock); + kfree(vmsg_o->buf); + kfree(vmsg_o); + 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, "i2c-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) { + dev_err(&vdev->dev, "failed to add virtio-i2c adapter.\n"); + virtio_i2c_del_vqs(vdev); + } + + 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_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 */