On Fri, 2020-04-17 at 10:10 -0700, Jeff Kirsher wrote:
> From: Dave Ertman <david.m.ertman@xxxxxxxxx>
>
> This is the initial implementation of the Virtual Bus,
> virtbus_device and virtbus_driver. The virtual bus is
> a software based bus intended to support registering
> virtbus_devices and virtbus_drivers and provide matching
> between them and probing of the registered drivers.
>
> The bus will support probe/remove shutdown and
> suspend/resume callbacks.
>
> Kconfig and Makefile alterations are included
>
> Signed-off-by: Dave Ertman <david.m.ertman@xxxxxxxxx>
> Signed-off-by: Kiran Patil <kiran.patil@xxxxxxxxx>
> Tested-by: Andrew Bowers <andrewx.bowers@xxxxxxxxx>
> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@xxxxxxxxx>
> ---
> Documentation/driver-api/virtual_bus.rst | 62 ++++++
> drivers/bus/Kconfig | 10 +
> drivers/bus/Makefile | 2 +
> drivers/bus/virtual_bus.c | 270
> +++++++++++++++++++++++
> include/linux/mod_devicetable.h | 8 +
> include/linux/virtual_bus.h | 53 +++++
> scripts/mod/devicetable-offsets.c | 3 +
> scripts/mod/file2alias.c | 7 +
> 8 files changed, 415 insertions(+)
> create mode 100644 Documentation/driver-api/virtual_bus.rst
> create mode 100644 drivers/bus/virtual_bus.c
> create mode 100644 include/linux/virtual_bus.h
>
> diff --git a/Documentation/driver-api/virtual_bus.rst
> b/Documentation/driver-api/virtual_bus.rst
> new file mode 100644
> index 000000000000..a79db0e9231e
> --- /dev/null
> +++ b/Documentation/driver-api/virtual_bus.rst
> @@ -0,0 +1,62 @@
> +===============================
> +Virtual Bus Devices and Drivers
> +===============================
> +
> +See <linux/virtual_bus.h> for the models for virtbus_device and
> virtbus_driver.
> +This bus is meant to be a lightweight software based bus to attach
> generic
> +devices and drivers to so that a chunk of data can be passed between
> them.
> +
> +One use case example is an RDMA driver needing to connect with
> several
> +different types of PCI LAN devices to be able to request resources
> from
> +them (queue sets). Each LAN driver that supports RDMA will register
> a
> +virtbus_device on the virtual bus for each physical function. The
> RDMA
> +driver will register as a virtbus_driver on the virtual bus to be
> +matched up with multiple virtbus_devices and receive a pointer to a
> +struct containing the callbacks that the PCI LAN drivers support for
> +registering with them.
> +
> +Sections in this document:
> + Virtbus devices
> + Virtbus drivers
> + Device Enumeration
> + Device naming and driver binding
> + Virtual Bus API entry points
> +
> +Virtbus devices
> +~~~~~~~~~~~~~~~
> +Virtbus_devices support the minimal device functionality. Devices
> will
> +accept a name, and then, when added to the virtual bus, an
> automatically
> +generated index is concatenated onto it for the virtbus_device-
> >name.
> +
> +Virtbus drivers
> +~~~~~~~~~~~~~~~
> +Virtbus drivers register with the virtual bus to be matched with
> virtbus
> +devices. They expect to be registered with a probe and remove
> callback,
> +and also support shutdown, suspend, and resume callbacks. They
> otherwise
> +follow the standard driver behavior of having discovery and
> enumeration
> +handled in the bus infrastructure.
> +
> +Virtbus drivers register themselves with the API entry point
> +virtbus_register_driver and unregister with
> virtbus_unregister_driver.
> +
> +Device Enumeration
> +~~~~~~~~~~~~~~~~~~
> +Enumeration is handled automatically by the bus infrastructure via
> the
> +ida_simple methods.
> +
> +Device naming and driver binding
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> +The virtbus_device.dev.name is the canonical name for the device. It
> is
> +built from two other parts:
> +
> + - virtbus_device.name (also used for matching).
> + - virtbus_device.id (generated automatically from ida_simple
> calls)
> +
> +Virtbus device IDs are always in "<name>.<instance>"
> format. Instances are
> +automatically selected through an ida_simple_get so are positive
> integers.
> +Name is taken from the device name field.
> +
> +Driver IDs are simple <name>.
> +
> +Need to extract the name from the Virtual Device compare to name of
> the
> +driver.
> diff --git a/drivers/bus/Kconfig b/drivers/bus/Kconfig
> index 6d4e4497b59b..8b6c709730ba 100644
> --- a/drivers/bus/Kconfig
> +++ b/drivers/bus/Kconfig
> @@ -203,4 +203,14 @@ config DA8XX_MSTPRI
> source "drivers/bus/fsl-mc/Kconfig"
> source "drivers/bus/mhi/Kconfig"
>
> +config VIRTUAL_BUS
> + tristate "Software based Virtual Bus"
> + help
> + Provides a software bus for virtbus_devices to be added to
> it
> + and virtbus_drivers to be registered on it. It matches
> driver
> + and device based on id and calls the driver's pobe routine.
> + One example is the irdma driver needing to connect with
> various
> + PCI LAN drivers to request resources (queues) to be able to
> perform
> + its function.
> +
> endmenu
> diff --git a/drivers/bus/Makefile b/drivers/bus/Makefile
> index 05f32cd694a4..d30828a4768c 100644
> --- a/drivers/bus/Makefile
> +++ b/drivers/bus/Makefile
> @@ -37,3 +37,5 @@ obj-$(CONFIG_DA8XX_MSTPRI) += da8xx-mstpri.o
>
> # MHI
> obj-$(CONFIG_MHI_BUS) += mhi/
> +
> +obj-$(CONFIG_VIRTUAL_BUS) += virtual_bus.o
> diff --git a/drivers/bus/virtual_bus.c b/drivers/bus/virtual_bus.c
> new file mode 100644
> index 000000000000..fb14cca40eea
> --- /dev/null
> +++ b/drivers/bus/virtual_bus.c
> @@ -0,0 +1,270 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * virtual_bus.c - lightweight software based bus for virtual
> devices
> + *
> + * Copyright (c) 2019-20 Intel Corporation
> + *
> + * Please see Documentation/driver-api/virtual_bus.rst for
> + * more information
> + */
> +
> +#include <linux/string.h>
> +#include <linux/virtual_bus.h>
> +#include <linux/of_irq.h>
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/pm_domain.h>
> +#include <linux/acpi.h>
> +#include <linux/device.h>
> +
> +MODULE_LICENSE("GPL v2");
> +MODULE_DESCRIPTION("Virtual Bus");
> +MODULE_AUTHOR("David Ertman <david.m.ertman@xxxxxxxxx>");
> +MODULE_AUTHOR("Kiran Patil <kiran.patil@xxxxxxxxx>");
> +
> +static DEFINE_IDA(virtbus_dev_ida);
> +
> +static const
> +struct virtbus_dev_id *virtbus_match_id(const struct virtbus_dev_id
> *id,
> + struct virtbus_device *vdev)
> +{
> + while (id->name[0]) {
> + if (!strcmp(vdev->name, id->name))
> + return id;
> + id++;
> + }
> + return NULL;
> +}
> +
> +static int virtbus_match(struct device *dev, struct device_driver
> *drv)
> +{
> + struct virtbus_driver *vdrv = to_virtbus_drv(drv);
> + struct virtbus_device *vdev = to_virtbus_dev(dev);
> +
> + return virtbus_match_id(vdrv->id_table, vdev) != NULL;
> +}
> +
> +static int virtbus_probe(struct device *dev)
> +{
> + return dev->driver->probe(dev);
> +}
> +
> +static int virtbus_remove(struct device *dev)
> +{
> + return dev->driver->remove(dev);
> +}
> +
> +static void virtbus_shutdown(struct device *dev)
> +{
> + dev->driver->shutdown(dev);
> +}
> +
> +static int virtbus_suspend(struct device *dev, pm_message_t state)
> +{
> + if (dev->driver->suspend)
> + return dev->driver->suspend(dev, state);
> +
> + return 0;
> +}
> +
> +static int virtbus_resume(struct device *dev)
> +{
> + if (dev->driver->resume)
> + return dev->driver->resume(dev);
> +
> + return 0;
> +}
> +
> +struct bus_type virtual_bus_type = {
> + .name = "virtbus",
> + .match = virtbus_match,
> + .probe = virtbus_probe,
> + .remove = virtbus_remove,
> + .shutdown = virtbus_shutdown,
> + .suspend = virtbus_suspend,
> + .resume = virtbus_resume,
> +};
> +
> +/**
> + * virtbus_release_device - Destroy a virtbus device
> + * @_dev: device to release
> + */
> +static void virtbus_release_device(struct device *_dev)
> +{
> + struct virtbus_device *vdev = to_virtbus_dev(_dev);
> +
> + ida_simple_remove(&virtbus_dev_ida, vdev->id);
> + vdev->release(vdev);
> +}
> +
> +/**
> + * virtbus_register_device - add a virtual bus device
> + * @vdev: virtual bus device to add
> + */
> +int virtbus_register_device(struct virtbus_device *vdev)
> +{
> + int ret;
> +
> + /* Do this first so that all error paths perform a put_device
> */
> + device_initialize(&vdev->dev);
> +
> + if (!vdev->release) {
> + ret = -EINVAL;
> + dev_err(&vdev->dev, "virtbus_device MUST have a
> .release callback that does something.\n");
> + goto device_pre_err;
> + }
> +
> + /* All device IDs are automatically allocated */
> + ret = ida_simple_get(&virtbus_dev_ida, 0, 0, GFP_KERNEL);
> + if (ret < 0) {
> + dev_err(&vdev->dev, "get IDA idx for virtbus device
> failed!\n");
> + goto device_pre_err;
> + }
> +
> +
> + vdev->dev.bus = &virtual_bus_type;
> + vdev->dev.release = virtbus_release_device;
> +
> + vdev->id = ret;
> + dev_set_name(&vdev->dev, "%s.%d", vdev->name, vdev->id);
> +
> + dev_dbg(&vdev->dev, "Registering virtbus device '%s'\n",
> + dev_name(&vdev->dev));
> +
> + ret = device_add(&vdev->dev);
> + if (ret)
> + goto device_add_err;
> +
> + return 0;
> +
> +device_add_err:
> + ida_simple_remove(&virtbus_dev_ida, vdev->id);
> +
> +device_pre_err:
> + dev_err(&vdev->dev, "Add device to virtbus failed!: %d\n",
> ret);
> + put_device(&vdev->dev);
> +
> + return ret;
> +}
> +EXPORT_SYMBOL_GPL(virtbus_register_device);
> +
> +/**
> + * virtbus_unregister_device - remove a virtual bus device
> + * @vdev: virtual bus device we are removing
> + */
> +void virtbus_unregister_device(struct virtbus_device *vdev)
> +{
> + device_del(&vdev->dev);
> + put_device(&vdev->dev);
> +}
> +EXPORT_SYMBOL_GPL(virtbus_unregister_device);
> +
> +static int virtbus_probe_driver(struct device *_dev)
> +{
> + struct virtbus_driver *vdrv = to_virtbus_drv(_dev->driver);
> + struct virtbus_device *vdev = to_virtbus_dev(_dev);
> + int ret;
> +
> + ret = dev_pm_domain_attach(_dev, true);
> + if (ret) {
> + dev_warn(_dev, "Failed to attatch to PM Domain : %d\n",
> ret);
> + return ret;
> + }
> +
> + ret = vdrv->probe(vdev);
> + if (ret) {
> + dev_err(&vdev->dev, "Probe returned error\n");
> + dev_pm_domain_detach(_dev, true);
> + }
> +
> + return ret;
> +}
> +
> +static int virtbus_remove_driver(struct device *_dev)
> +{
> + struct virtbus_driver *vdrv = to_virtbus_drv(_dev->driver);
> + struct virtbus_device *vdev = to_virtbus_dev(_dev);
> + int ret = 0;
> +
> + ret = vdrv->remove(vdev);
> + dev_pm_domain_detach(_dev, true);
> +
> + return ret;
> +}
> +
> +static void virtbus_shutdown_driver(struct device *_dev)
> +{
> + struct virtbus_driver *vdrv = to_virtbus_drv(_dev->driver);
> + struct virtbus_device *vdev = to_virtbus_dev(_dev);
> +
> + vdrv->shutdown(vdev);
> +}
> +
> +static int virtbus_suspend_driver(struct device *_dev, pm_message_t
> state)
> +{
> + struct virtbus_driver *vdrv = to_virtbus_drv(_dev->driver);
> + struct virtbus_device *vdev = to_virtbus_dev(_dev);
> +
> + if (vdrv->suspend)
> + return vdrv->suspend(vdev, state);
> +
> + return 0;
> +}
> +
> +static int virtbus_resume_driver(struct device *_dev)
> +{
> + struct virtbus_driver *vdrv = to_virtbus_drv(_dev->driver);
> + struct virtbus_device *vdev = to_virtbus_dev(_dev);
> +
> + if (vdrv->resume)
> + return vdrv->resume(vdev);
> +
> + return 0;
> +}
> +
> +/**
> + * __virtbus_register_driver - register a driver for virtual bus
> devices
> + * @vdrv: virtbus_driver structure
> + * @owner: owning module/driver
> + */
> +int __virtbus_register_driver(struct virtbus_driver *vdrv, struct
> module *owner)
> +{
> + if (!vdrv->probe || !vdrv->remove || !vdrv->shutdown || !vdrv-
> >id_table)
> + return -EINVAL;
> +
> + vdrv->driver.owner = owner;
> + vdrv->driver.bus = &virtual_bus_type;
> + vdrv->driver.probe = virtbus_probe_driver;
> + vdrv->driver.remove = virtbus_remove_driver;
> + vdrv->driver.shutdown = virtbus_shutdown_driver;
> + vdrv->driver.suspend = virtbus_suspend_driver;
> + vdrv->driver.resume = virtbus_resume_driver;
Do we need the above callbacks here and in bus_type?
I'm seeing the following message when I experimented with the
virtualbus implementation in the audio driver. Removing them from the
bus_type gets rid of this message.
"Driver 'sof-ipc-test-virtbus-drv' needs updating - please use bus_type
methods"
Thanks,
Ranjani
> +
> + return driver_register(&vdrv->driver);
> +}
> +EXPORT_SYMBOL_GPL(__virtbus_register_driver);
> +
> +/**
> + * virtbus_unregister_driver - unregister a driver for virtual bus
> devices
> + * @vdrv: virtbus_driver structure
> + */
> +void virtbus_unregister_driver(struct virtbus_driver *vdrv)
> +{
> + driver_unregister(&vdrv->driver);
> +}
> +EXPORT_SYMBOL_GPL(virtbus_unregister_driver);
> +
> +static int __init virtual_bus_init(void)
> +{
> + return bus_register(&virtual_bus_type);
> +}
> +
> +static void __exit virtual_bus_exit(void)
> +{
> + bus_unregister(&virtual_bus_type);
> + ida_destroy(&virtbus_dev_ida);
> +}
> +
> +module_init(virtual_bus_init);
> +module_exit(virtual_bus_exit);
> diff --git a/include/linux/mod_devicetable.h
> b/include/linux/mod_devicetable.h
> index 4c2ddd0941a7..60bcfe75fb94 100644
> --- a/include/linux/mod_devicetable.h
> +++ b/include/linux/mod_devicetable.h
> @@ -832,4 +832,12 @@ struct mhi_device_id {
> kernel_ulong_t driver_data;
> };
>
> +#define VIRTBUS_NAME_SIZE 20
> +#define VIRTBUS_MODULE_PREFIX "virtbus:"
> +
> +struct virtbus_dev_id {
> + char name[VIRTBUS_NAME_SIZE];
> + kernel_ulong_t driver_data;
> +};
> +
> #endif /* LINUX_MOD_DEVICETABLE_H */
> diff --git a/include/linux/virtual_bus.h
> b/include/linux/virtual_bus.h
> new file mode 100644
> index 000000000000..4df06178e72f
> --- /dev/null
> +++ b/include/linux/virtual_bus.h
> @@ -0,0 +1,53 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/*
> + * virtual_bus.h - lightweight software bus
> + *
> + * Copyright (c) 2019-20 Intel Corporation
> + *
> + * Please see Documentation/driver-api/virtual_bus.rst for more
> information
> + */
> +
> +#ifndef _VIRTUAL_BUS_H_
> +#define _VIRTUAL_BUS_H_
> +
> +#include <linux/device.h>
> +
> +struct virtbus_device {
> + struct device dev;
> + const char *name;
> + void (*release)(struct virtbus_device *);
> + int id;
> +};
> +
> +struct virtbus_driver {
> + int (*probe)(struct virtbus_device *);
> + int (*remove)(struct virtbus_device *);
> + void (*shutdown)(struct virtbus_device *);
> + int (*suspend)(struct virtbus_device *, pm_message_t);
> + int (*resume)(struct virtbus_device *);
> + struct device_driver driver;
> + const struct virtbus_dev_id *id_table;
> +};
> +
> +static inline
> +struct virtbus_device *to_virtbus_dev(struct device *dev)
> +{
> + return container_of(dev, struct virtbus_device, dev);
> +}
> +
> +static inline
> +struct virtbus_driver *to_virtbus_drv(struct device_driver *drv)
> +{
> + return container_of(drv, struct virtbus_driver, driver);
> +}
> +
> +int virtbus_register_device(struct virtbus_device *vdev);
> +void virtbus_unregister_device(struct virtbus_device *vdev);
> +int
> +__virtbus_register_driver(struct virtbus_driver *vdrv, struct module
> *owner);
> +void virtbus_unregister_driver(struct virtbus_driver *vdrv);
> +
> +#define virtbus_register_driver(vdrv) \
> + __virtbus_register_driver(vdrv, THIS_MODULE)
> +
> +#endif /* _VIRTUAL_BUS_H_ */
> diff --git a/scripts/mod/devicetable-offsets.c
> b/scripts/mod/devicetable-offsets.c
> index 010be8ba2116..0c8e0e3a7c84 100644
> --- a/scripts/mod/devicetable-offsets.c
> +++ b/scripts/mod/devicetable-offsets.c
> @@ -241,5 +241,8 @@ int main(void)
> DEVID(mhi_device_id);
> DEVID_FIELD(mhi_device_id, chan);
>
> + DEVID(virtbus_dev_id);
> + DEVID_FIELD(virtbus_dev_id, name);
> +
> return 0;
> }
> diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c
> index 02d5d79da284..7d78fa3fba34 100644
> --- a/scripts/mod/file2alias.c
> +++ b/scripts/mod/file2alias.c
> @@ -1358,7 +1358,13 @@ static int do_mhi_entry(const char *filename,
> void *symval, char *alias)
> {
> DEF_FIELD_ADDR(symval, mhi_device_id, chan);
> sprintf(alias, MHI_DEVICE_MODALIAS_FMT, *chan);
> + return 1;
> +}
>
> +static int do_virtbus_entry(const char *filename, void *symval, char
> *alias)
> +{
> + DEF_FIELD_ADDR(symval, virtbus_dev_id, name);
> + sprintf(alias, VIRTBUS_MODULE_PREFIX "%s", *name);
> return 1;
> }
>
> @@ -1436,6 +1442,7 @@ static const struct devtable devtable[] = {
> {"tee", SIZE_tee_client_device_id, do_tee_entry},
> {"wmi", SIZE_wmi_device_id, do_wmi_entry},
> {"mhi", SIZE_mhi_device_id, do_mhi_entry},
> + {"virtbus", SIZE_virtbus_dev_id, do_virtbus_entry},
> };
>
> /* Create MODULE_ALIAS() statements.
