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.c...@intel.com> Signed-off-by: Conghui Chen <conghui.c...@intel.com> Signed-off-by: Jie Deng <jie.d...@intel.com> Reviewed-by: Shuo Liu <shuo.a....@intel.com> Reviewed-by: Andy Shevchenko <andriy.shevche...@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; + +/** + * 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 _______________________________________________ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
