Commit 6e7f3ee9 authored by Dave Jiang's avatar Dave Jiang Committed by Vinod Koul
Browse files

dmaengine: idxd: move dsa_drv support to compatible mode 



The original architecture of /sys/bus/dsa invented a scheme whereby
a single entry in the list of bus drivers, /sys/bus/drivers/dsa,
handled all device types and internally routed them to different
different drivers. Those internal drivers were invisible to
userspace.

With the idxd driver transitioned to a proper bus device-driver model,
the legacy behavior needs to be preserved due to it being exposed to
user space via sysfs. Create a compat driver to provide the legacy
behavior for /sys/bus/dsa/drivers/dsa. This should satisfy user
tool accel-config v3.2 or ealier where this behavior is expected.
If the distro has a newer accel-config then the legacy mode does
not need to be enabled.

When the compat driver binds the device (i.e. dsa0) to the dsa driver,
it will be bound to the new idxd_drv. The wq device (i.e. wq0.0) will
be bound to either the dmaengine_drv or the user_drv. The dsa_drv
becomes a routing mechansim for the new drivers. It will not support
additional external drivers that are implemented later.

Reviewed-by: default avatarDan Williams <dan.j.williams@intel.com>
Signed-off-by: default avatarDave Jiang <dave.jiang@intel.com>
Link: https://lore.kernel.org/r/162637468705.744545.4399080971745974435.stgit@djiang5-desk3.ch.intel.com


Signed-off-by: default avatarVinod Koul <vkoul@kernel.org>
parent d9e5481f

drivers/dma/Kconfig

+17 −0
Original line number Diff line number Diff line
@@ -295,6 +295,23 @@ config INTEL_IDXD 


	  If unsure, say N.



config INTEL_IDXD_COMPAT

	bool "Legacy behavior for idxd driver"

	depends on PCI && X86_64

	select INTEL_IDXD_BUS

	help

	  Compatible driver to support old /sys/bus/dsa/drivers/dsa behavior.

	  The old behavior performed driver bind/unbind for device and wq

	  devices all under the dsa driver. The compat driver will emulate

	  the legacy behavior in order to allow existing support apps (i.e.

	  accel-config) to continue function. It is expected that accel-config

	  v3.2 and earlier will need the compat mode. A distro with later

	  accel-config version can disable this compat config.



	  Say Y if you have old applications that require such behavior.



	  If unsure, say N.



# Config symbol that collects all the dependencies that's necessary to

# support shared virtual memory for the devices supported by idxd.

config INTEL_IDXD_SVM

drivers/dma/idxd/Makefile

+3 −0
Original line number Diff line number Diff line
@@ -7,3 +7,6 @@ idxd-$(CONFIG_INTEL_IDXD_PERFMON) += perfmon.o 


obj-$(CONFIG_INTEL_IDXD_BUS) += idxd_bus.o

idxd_bus-y := bus.o



obj-$(CONFIG_INTEL_IDXD_COMPAT) += idxd_compat.o

idxd_compat-y := compat.o

drivers/dma/idxd/cdev.c

+1 −0
Original line number Diff line number Diff line
@@ -356,6 +356,7 @@ struct idxd_device_driver idxd_user_drv = { 
	.name = "user",

	.type = dev_types,

};

EXPORT_SYMBOL_GPL(idxd_user_drv);



int idxd_cdev_register(void)

{

drivers/dma/idxd/compat.c

0 → 100644
+114 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0

/* Copyright(c) 2021 Intel Corporation. All rights rsvd. */

#include <linux/init.h>

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/device.h>

#include <linux/device/bus.h>

#include "idxd.h"



extern int device_driver_attach(struct device_driver *drv, struct device *dev);

extern void device_driver_detach(struct device *dev);



#define DRIVER_ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store)	\

	struct driver_attribute driver_attr_##_name =		\

	__ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store)



static ssize_t unbind_store(struct device_driver *drv, const char *buf, size_t count)

{

	struct bus_type *bus = drv->bus;

	struct device *dev;

	int rc = -ENODEV;



	dev = bus_find_device_by_name(bus, NULL, buf);

	if (dev && dev->driver) {

		device_driver_detach(dev);

		rc = count;

	}



	return rc;

}

static DRIVER_ATTR_IGNORE_LOCKDEP(unbind, 0200, NULL, unbind_store);



static ssize_t bind_store(struct device_driver *drv, const char *buf, size_t count)

{

	struct bus_type *bus = drv->bus;

	struct device *dev;

	struct device_driver *alt_drv;

	int rc = -ENODEV;

	struct idxd_dev *idxd_dev;



	dev = bus_find_device_by_name(bus, NULL, buf);

	if (!dev || dev->driver || drv != &dsa_drv.drv)

		return -ENODEV;



	idxd_dev = confdev_to_idxd_dev(dev);

	if (is_idxd_dev(idxd_dev)) {

		alt_drv = driver_find("idxd", bus);

		if (!alt_drv)

			return -ENODEV;

	} else if (is_idxd_wq_dev(idxd_dev)) {

		struct idxd_wq *wq = confdev_to_wq(dev);



		if (is_idxd_wq_kernel(wq)) {

			alt_drv = driver_find("dmaengine", bus);

			if (!alt_drv)

				return -ENODEV;

		} else if (is_idxd_wq_user(wq)) {

			alt_drv = driver_find("user", bus);

			if (!alt_drv)

				return -ENODEV;

		} else {

			return -ENODEV;

		}

	}



	rc = device_driver_attach(alt_drv, dev);

	if (rc < 0)

		return rc;



	return count;

}

static DRIVER_ATTR_IGNORE_LOCKDEP(bind, 0200, NULL, bind_store);



static struct attribute *dsa_drv_compat_attrs[] = {

	&driver_attr_bind.attr,

	&driver_attr_unbind.attr,

	NULL,

};



static const struct attribute_group dsa_drv_compat_attr_group = {

	.attrs = dsa_drv_compat_attrs,

};



static const struct attribute_group *dsa_drv_compat_groups[] = {

	&dsa_drv_compat_attr_group,

	NULL,

};



static int idxd_dsa_drv_probe(struct idxd_dev *idxd_dev)

{

	return -ENODEV;

}



static void idxd_dsa_drv_remove(struct idxd_dev *idxd_dev)

{

}



static enum idxd_dev_type dev_types[] = {

	IDXD_DEV_NONE,

};



struct idxd_device_driver dsa_drv = {

	.name = "dsa",

	.probe = idxd_dsa_drv_probe,

	.remove = idxd_dsa_drv_remove,

	.type = dev_types,

	.drv = {

		.suppress_bind_attrs = true,

		.groups = dsa_drv_compat_groups,

	},

};



module_idxd_driver(dsa_drv);

MODULE_IMPORT_NS(IDXD);

drivers/dma/idxd/device.c

+1 −0
Original line number Diff line number Diff line
@@ -1318,3 +1318,4 @@ struct idxd_device_driver idxd_drv = { 
	.remove = idxd_device_drv_remove,

	.name = "idxd",

};

EXPORT_SYMBOL_GPL(idxd_drv);