new file mode 100644
@@ -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.
@@ -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
@@ -37,3 +37,5 @@ obj-$(CONFIG_DA8XX_MSTPRI) += da8xx-mstpri.o
# MHI
obj-$(CONFIG_MHI_BUS) += mhi/
+
+obj-$(CONFIG_VIRTUAL_BUS) += virtual_bus.o
new file mode 100644
@@ -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@intel.com>");
+MODULE_AUTHOR("Kiran Patil <kiran.patil@intel.com>");
+
+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;
+
+ 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);
@@ -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 */
new file mode 100644
@@ -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_ */
@@ -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;
}
@@ -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.