This patchset supports some dfl device drivers written in userspace.
In the patchset v1, the "driver_override" interface should be used to bind
the DFL UIO driver to DFL devices. But there is concern that the
"driver_override" interface is not OK itself.
In v2, we use a new matching algorithem. The "driver_override" interface
is abandoned, the DFL UIO driver matches any DFL device which could not be
handled by other DFL drivers. So the DFL UIO driver could be used for new
DFL devices which are not supported by kernel. The concern is the UIO may
not be suitable as a default/generic driver for all dfl features, such as
features with multiple interrupts.
In v4, we specify each matching device in the id_table of the UIO driver,
just the same as other dfl drivers do. Now the UIO driver supports Ether
Group feature. To support more DFL features, their feature ids should be
added to the driver's id_table.
Before v9, we create a "uio_pdrv_genirq" platform device using DFL devices'
resources. Then we leverage the uio_pdrv_genirq driver for UIO support. It
is suggested that we implement a driver in drivers/uio that directly calls
UIO framework APIs. So we implement the uio_dfl driver in v9. The driver
now only binds the ether group feature, which has no irq. So the irq
support is not implemented yet.
Main changes from v1:
- switch to the new matching algorithem. It matches DFL devices which could
not be handled by other DFL drivers.
- refacor the code about device resources filling.
- add the documentation.
Main changes from v2:
- split the match ops changes in dfl.c to an independent patch.
- move the declarations needed for dfl-uio-pdev from include/linux/dfl.h
to driver/fpga/dfl.h
- some minor fixes.
Main changes from v3:
- switch to specifying each matching device in the driver's id_table.
- refactor the irq handling code.
Main changes from v4:
- refactor the irq handling code.
Main changes from v5:
- fix the res[] zero initialization issue.
- improve the return code for probe().
- some doc improvement.
Main changes from v6:
- use platform_device_register_resndata() for pdev creation.
Main changes from v7:
- some doc fixes.
Main changes from v8:
- switch to add a uio driver in drivers/uio
Main changes from v9:
- add this source file in MAINTAINERS
- improve the Kconfig, add more descriptive Kconfig header, add detailed
path for opae uio example in Kconfig.
Main changes from v10:
- add description in doc that interrupt support is not implemented yet.
Xu Yilun (2):
uio: uio_dfl: add userspace i/o driver for DFL bus
Documentation: fpga: dfl: Add description for DFL UIO support
Documentation/fpga/dfl.rst | 26 ++++++++++++++++++
MAINTAINERS | 1 +
drivers/uio/Kconfig | 17 ++++++++++++
drivers/uio/Makefile | 1 +
drivers/uio/uio_dfl.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++
5 files changed, 111 insertions(+)
create mode 100644 drivers/uio/uio_dfl.c
--
2.7.4
This patch supports the DFL drivers be written in userspace. This is
realized by exposing the userspace I/O device interfaces.
The driver now only binds the ether group feature, which has no irq. So
the irq support is not implemented yet.
Signed-off-by: Xu Yilun <[email protected]>
Reviewed-by: Tom Rix <[email protected]>
---
v9: switch to add a uio driver in drivers/uio
v10: add the source file in MAINTAINERS
more descriptive Kconfig header
add detailed path for opae uio example
v11: no change
---
MAINTAINERS | 1 +
drivers/uio/Kconfig | 17 +++++++++++++
drivers/uio/Makefile | 1 +
drivers/uio/uio_dfl.c | 66 +++++++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 85 insertions(+)
create mode 100644 drivers/uio/uio_dfl.c
diff --git a/MAINTAINERS b/MAINTAINERS
index 000fe0b..4dc0354 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6943,6 +6943,7 @@ S: Maintained
F: Documentation/ABI/testing/sysfs-bus-dfl*
F: Documentation/fpga/dfl.rst
F: drivers/fpga/dfl*
+F: drivers/uio/uio_dfl.c
F: include/linux/dfl.h
F: include/uapi/linux/fpga-dfl.h
diff --git a/drivers/uio/Kconfig b/drivers/uio/Kconfig
index 202ee81..5531f3a 100644
--- a/drivers/uio/Kconfig
+++ b/drivers/uio/Kconfig
@@ -165,4 +165,21 @@ config UIO_HV_GENERIC
to network and storage devices from userspace.
If you compile this as a module, it will be called uio_hv_generic.
+
+config UIO_DFL
+ tristate "Generic driver for DFL (Device Feature List) bus"
+ depends on FPGA_DFL
+ help
+ Generic DFL (Device Feature List) driver for Userspace I/O devices.
+ It is useful to provide direct access to DFL devices from userspace.
+ A sample userspace application using this driver is available for
+ download in a git repository:
+
+ git clone https://github.com/OPAE/opae-sdk.git
+
+ It could be found at:
+
+ opae-sdk/tools/libopaeuio/
+
+ If you compile this as a module, it will be called uio_dfl.
endif
diff --git a/drivers/uio/Makefile b/drivers/uio/Makefile
index c285dd2..f2f416a1 100644
--- a/drivers/uio/Makefile
+++ b/drivers/uio/Makefile
@@ -11,3 +11,4 @@ obj-$(CONFIG_UIO_PRUSS) += uio_pruss.o
obj-$(CONFIG_UIO_MF624) += uio_mf624.o
obj-$(CONFIG_UIO_FSL_ELBC_GPCM) += uio_fsl_elbc_gpcm.o
obj-$(CONFIG_UIO_HV_GENERIC) += uio_hv_generic.o
+obj-$(CONFIG_UIO_DFL) += uio_dfl.o
diff --git a/drivers/uio/uio_dfl.c b/drivers/uio/uio_dfl.c
new file mode 100644
index 0000000..89c0fc7
--- /dev/null
+++ b/drivers/uio/uio_dfl.c
@@ -0,0 +1,66 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Generic DFL driver for Userspace I/O devicess
+ *
+ * Copyright (C) 2021 Intel Corporation, Inc.
+ */
+#include <linux/dfl.h>
+#include <linux/errno.h>
+#include <linux/module.h>
+#include <linux/uio_driver.h>
+
+#define DRIVER_NAME "uio_dfl"
+
+static int uio_dfl_probe(struct dfl_device *ddev)
+{
+ struct resource *r = &ddev->mmio_res;
+ struct device *dev = &ddev->dev;
+ struct uio_info *uioinfo;
+ struct uio_mem *uiomem;
+ int ret;
+
+ uioinfo = devm_kzalloc(dev, sizeof(struct uio_info), GFP_KERNEL);
+ if (!uioinfo)
+ return -ENOMEM;
+
+ uioinfo->name = DRIVER_NAME;
+ uioinfo->version = "0";
+
+ uiomem = &uioinfo->mem[0];
+ uiomem->memtype = UIO_MEM_PHYS;
+ uiomem->addr = r->start & PAGE_MASK;
+ uiomem->offs = r->start & ~PAGE_MASK;
+ uiomem->size = (uiomem->offs + resource_size(r)
+ + PAGE_SIZE - 1) & PAGE_MASK;
+ uiomem->name = r->name;
+
+ /* Irq is yet to be supported */
+ uioinfo->irq = UIO_IRQ_NONE;
+
+ ret = devm_uio_register_device(dev, uioinfo);
+ if (ret)
+ dev_err(dev, "unable to register uio device\n");
+
+ return ret;
+}
+
+#define FME_FEATURE_ID_ETH_GROUP 0x10
+
+static const struct dfl_device_id uio_dfl_ids[] = {
+ { FME_ID, FME_FEATURE_ID_ETH_GROUP },
+ { }
+};
+MODULE_DEVICE_TABLE(dfl, uio_dfl_ids);
+
+static struct dfl_driver uio_dfl_driver = {
+ .drv = {
+ .name = DRIVER_NAME,
+ },
+ .id_table = uio_dfl_ids,
+ .probe = uio_dfl_probe,
+};
+module_dfl_driver(uio_dfl_driver);
+
+MODULE_DESCRIPTION("Generic DFL driver for Userspace I/O devices");
+MODULE_AUTHOR("Intel Corporation");
+MODULE_LICENSE("GPL v2");
--
2.7.4
This patch adds description for UIO support for dfl devices on DFL
bus.
Signed-off-by: Xu Yilun <[email protected]>
Reviewed-by: Tom Rix <[email protected]>
Reviewed-by: Wu Hao <[email protected]>
---
v2: no doc in v1, add it for v2.
v3: some documentation fixes.
v4: documentation change since the driver matching is changed.
v5: no change.
v6: improve the title of the userspace driver support section.
some word improvement.
v7: rebased to next-20210119
v8: some doc fixes.
v9: some doc change since we switch to the driver in drivers/uio.
v10: no change.
v11: add description that interrupt support is not implemented yet.
---
Documentation/fpga/dfl.rst | 26 ++++++++++++++++++++++++++
1 file changed, 26 insertions(+)
diff --git a/Documentation/fpga/dfl.rst b/Documentation/fpga/dfl.rst
index c41ac76..f3a1223 100644
--- a/Documentation/fpga/dfl.rst
+++ b/Documentation/fpga/dfl.rst
@@ -7,6 +7,7 @@ Authors:
- Enno Luebbers <[email protected]>
- Xiao Guangrong <[email protected]>
- Wu Hao <[email protected]>
+- Xu Yilun <[email protected]>
The Device Feature List (DFL) FPGA framework (and drivers according to
this framework) hides the very details of low layer hardwares and provides
@@ -530,6 +531,31 @@ Being able to specify more than one DFL per BAR has been considered, but it
was determined the use case did not provide value. Specifying a single DFL
per BAR simplifies the implementation and allows for extra error checking.
+
+Userspace driver support for DFL devices
+========================================
+The purpose of an FPGA is to be reprogrammed with newly developed hardware
+components. New hardware can instantiate a new private feature in the DFL, and
+then present a DFL device in the system. In some cases users may need a
+userspace driver for the DFL device:
+
+* Users may need to run some diagnostic test for their hardware.
+* Users may prototype the kernel driver in user space.
+* Some hardware is designed for specific purposes and does not fit into one of
+ the standard kernel subsystems.
+
+This requires direct access to MMIO space and interrupt handling from
+userspace. The uio_dfl module exposes the UIO device interfaces for this
+purpose.
+
+Currently the uio_dfl driver only supports the Ether Group sub feature, which
+has no irq in hardware. So the interrupt handling is not added in this driver.
+
+UIO_DFL should be selected to enable the uio_dfl module driver. To support a
+new DFL feature via UIO direct access, its feature id should be added to the
+driver's id_table.
+
+
Open discussion
===============
FME driver exports one ioctl (DFL_FPGA_FME_PORT_PR) for partial reconfiguration
--
2.7.4
On Sat, Feb 27, 2021 at 11:27:03PM +0800, Xu Yilun wrote:
> This patch supports the DFL drivers be written in userspace. This is
> realized by exposing the userspace I/O device interfaces.
>
> The driver now only binds the ether group feature, which has no irq. So
> the irq support is not implemented yet.
>
> Signed-off-by: Xu Yilun <[email protected]>
> Reviewed-by: Tom Rix <[email protected]>
> ---
> v9: switch to add a uio driver in drivers/uio
> v10: add the source file in MAINTAINERS
> more descriptive Kconfig header
> add detailed path for opae uio example
> v11: no change
> ---
> MAINTAINERS | 1 +
> drivers/uio/Kconfig | 17 +++++++++++++
> drivers/uio/Makefile | 1 +
> drivers/uio/uio_dfl.c | 66 +++++++++++++++++++++++++++++++++++++++++++++++++++
> 4 files changed, 85 insertions(+)
> create mode 100644 drivers/uio/uio_dfl.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 000fe0b..4dc0354 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -6943,6 +6943,7 @@ S: Maintained
> F: Documentation/ABI/testing/sysfs-bus-dfl*
> F: Documentation/fpga/dfl.rst
> F: drivers/fpga/dfl*
> +F: drivers/uio/uio_dfl.c
> F: include/linux/dfl.h
> F: include/uapi/linux/fpga-dfl.h
>
> diff --git a/drivers/uio/Kconfig b/drivers/uio/Kconfig
> index 202ee81..5531f3a 100644
> --- a/drivers/uio/Kconfig
> +++ b/drivers/uio/Kconfig
> @@ -165,4 +165,21 @@ config UIO_HV_GENERIC
> to network and storage devices from userspace.
>
> If you compile this as a module, it will be called uio_hv_generic.
> +
> +config UIO_DFL
> + tristate "Generic driver for DFL (Device Feature List) bus"
> + depends on FPGA_DFL
> + help
> + Generic DFL (Device Feature List) driver for Userspace I/O devices.
> + It is useful to provide direct access to DFL devices from userspace.
> + A sample userspace application using this driver is available for
> + download in a git repository:
> +
> + git clone https://github.com/OPAE/opae-sdk.git
> +
> + It could be found at:
> +
> + opae-sdk/tools/libopaeuio/
> +
> + If you compile this as a module, it will be called uio_dfl.
> endif
> diff --git a/drivers/uio/Makefile b/drivers/uio/Makefile
> index c285dd2..f2f416a1 100644
> --- a/drivers/uio/Makefile
> +++ b/drivers/uio/Makefile
> @@ -11,3 +11,4 @@ obj-$(CONFIG_UIO_PRUSS) += uio_pruss.o
> obj-$(CONFIG_UIO_MF624) += uio_mf624.o
> obj-$(CONFIG_UIO_FSL_ELBC_GPCM) += uio_fsl_elbc_gpcm.o
> obj-$(CONFIG_UIO_HV_GENERIC) += uio_hv_generic.o
> +obj-$(CONFIG_UIO_DFL) += uio_dfl.o
> diff --git a/drivers/uio/uio_dfl.c b/drivers/uio/uio_dfl.c
> new file mode 100644
> index 0000000..89c0fc7
> --- /dev/null
> +++ b/drivers/uio/uio_dfl.c
> @@ -0,0 +1,66 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Generic DFL driver for Userspace I/O devicess
> + *
> + * Copyright (C) 2021 Intel Corporation, Inc.
> + */
> +#include <linux/dfl.h>
> +#include <linux/errno.h>
> +#include <linux/module.h>
> +#include <linux/uio_driver.h>
> +
> +#define DRIVER_NAME "uio_dfl"
> +
> +static int uio_dfl_probe(struct dfl_device *ddev)
> +{
> + struct resource *r = &ddev->mmio_res;
> + struct device *dev = &ddev->dev;
> + struct uio_info *uioinfo;
> + struct uio_mem *uiomem;
> + int ret;
> +
> + uioinfo = devm_kzalloc(dev, sizeof(struct uio_info), GFP_KERNEL);
> + if (!uioinfo)
> + return -ENOMEM;
> +
> + uioinfo->name = DRIVER_NAME;
> + uioinfo->version = "0";
> +
> + uiomem = &uioinfo->mem[0];
> + uiomem->memtype = UIO_MEM_PHYS;
> + uiomem->addr = r->start & PAGE_MASK;
> + uiomem->offs = r->start & ~PAGE_MASK;
> + uiomem->size = (uiomem->offs + resource_size(r)
> + + PAGE_SIZE - 1) & PAGE_MASK;
> + uiomem->name = r->name;
> +
> + /* Irq is yet to be supported */
> + uioinfo->irq = UIO_IRQ_NONE;
> +
> + ret = devm_uio_register_device(dev, uioinfo);
> + if (ret)
> + dev_err(dev, "unable to register uio device\n");
> +
> + return ret;
> +}
> +
> +#define FME_FEATURE_ID_ETH_GROUP 0x10
Why are you saying that an ethernet driver should be using the UIO
interface?
And why can't you use the existing UIO drivers that bind to memory
regions specified by firmware? Without an interrupt being used, why is
UIO needed at all?
thanks,
greg k-h
On Sat, Feb 27, 2021 at 04:42:55PM +0100, Greg KH wrote:
> On Sat, Feb 27, 2021 at 11:27:03PM +0800, Xu Yilun wrote:
> > This patch supports the DFL drivers be written in userspace. This is
> > realized by exposing the userspace I/O device interfaces.
> >
> > The driver now only binds the ether group feature, which has no irq. So
> > the irq support is not implemented yet.
> >
> > Signed-off-by: Xu Yilun <[email protected]>
> > Reviewed-by: Tom Rix <[email protected]>
> > ---
> > v9: switch to add a uio driver in drivers/uio
> > v10: add the source file in MAINTAINERS
> > more descriptive Kconfig header
> > add detailed path for opae uio example
> > v11: no change
> > ---
> > MAINTAINERS | 1 +
> > drivers/uio/Kconfig | 17 +++++++++++++
> > drivers/uio/Makefile | 1 +
> > drivers/uio/uio_dfl.c | 66 +++++++++++++++++++++++++++++++++++++++++++++++++++
> > 4 files changed, 85 insertions(+)
> > create mode 100644 drivers/uio/uio_dfl.c
> >
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 000fe0b..4dc0354 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -6943,6 +6943,7 @@ S: Maintained
> > F: Documentation/ABI/testing/sysfs-bus-dfl*
> > F: Documentation/fpga/dfl.rst
> > F: drivers/fpga/dfl*
> > +F: drivers/uio/uio_dfl.c
> > F: include/linux/dfl.h
> > F: include/uapi/linux/fpga-dfl.h
> >
> > diff --git a/drivers/uio/Kconfig b/drivers/uio/Kconfig
> > index 202ee81..5531f3a 100644
> > --- a/drivers/uio/Kconfig
> > +++ b/drivers/uio/Kconfig
> > @@ -165,4 +165,21 @@ config UIO_HV_GENERIC
> > to network and storage devices from userspace.
> >
> > If you compile this as a module, it will be called uio_hv_generic.
> > +
> > +config UIO_DFL
> > + tristate "Generic driver for DFL (Device Feature List) bus"
> > + depends on FPGA_DFL
> > + help
> > + Generic DFL (Device Feature List) driver for Userspace I/O devices.
> > + It is useful to provide direct access to DFL devices from userspace.
> > + A sample userspace application using this driver is available for
> > + download in a git repository:
> > +
> > + git clone https://github.com/OPAE/opae-sdk.git
> > +
> > + It could be found at:
> > +
> > + opae-sdk/tools/libopaeuio/
> > +
> > + If you compile this as a module, it will be called uio_dfl.
> > endif
> > diff --git a/drivers/uio/Makefile b/drivers/uio/Makefile
> > index c285dd2..f2f416a1 100644
> > --- a/drivers/uio/Makefile
> > +++ b/drivers/uio/Makefile
> > @@ -11,3 +11,4 @@ obj-$(CONFIG_UIO_PRUSS) += uio_pruss.o
> > obj-$(CONFIG_UIO_MF624) += uio_mf624.o
> > obj-$(CONFIG_UIO_FSL_ELBC_GPCM) += uio_fsl_elbc_gpcm.o
> > obj-$(CONFIG_UIO_HV_GENERIC) += uio_hv_generic.o
> > +obj-$(CONFIG_UIO_DFL) += uio_dfl.o
> > diff --git a/drivers/uio/uio_dfl.c b/drivers/uio/uio_dfl.c
> > new file mode 100644
> > index 0000000..89c0fc7
> > --- /dev/null
> > +++ b/drivers/uio/uio_dfl.c
> > @@ -0,0 +1,66 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Generic DFL driver for Userspace I/O devicess
> > + *
> > + * Copyright (C) 2021 Intel Corporation, Inc.
> > + */
> > +#include <linux/dfl.h>
> > +#include <linux/errno.h>
> > +#include <linux/module.h>
> > +#include <linux/uio_driver.h>
> > +
> > +#define DRIVER_NAME "uio_dfl"
> > +
> > +static int uio_dfl_probe(struct dfl_device *ddev)
> > +{
> > + struct resource *r = &ddev->mmio_res;
> > + struct device *dev = &ddev->dev;
> > + struct uio_info *uioinfo;
> > + struct uio_mem *uiomem;
> > + int ret;
> > +
> > + uioinfo = devm_kzalloc(dev, sizeof(struct uio_info), GFP_KERNEL);
> > + if (!uioinfo)
> > + return -ENOMEM;
> > +
> > + uioinfo->name = DRIVER_NAME;
> > + uioinfo->version = "0";
> > +
> > + uiomem = &uioinfo->mem[0];
> > + uiomem->memtype = UIO_MEM_PHYS;
> > + uiomem->addr = r->start & PAGE_MASK;
> > + uiomem->offs = r->start & ~PAGE_MASK;
> > + uiomem->size = (uiomem->offs + resource_size(r)
> > + + PAGE_SIZE - 1) & PAGE_MASK;
> > + uiomem->name = r->name;
> > +
> > + /* Irq is yet to be supported */
> > + uioinfo->irq = UIO_IRQ_NONE;
> > +
> > + ret = devm_uio_register_device(dev, uioinfo);
> > + if (ret)
> > + dev_err(dev, "unable to register uio device\n");
> > +
> > + return ret;
> > +}
> > +
> > +#define FME_FEATURE_ID_ETH_GROUP 0x10
>
> Why are you saying that an ethernet driver should be using the UIO
> interface?
The ETH GROUP IP is not designed as the full functional ethernet
controller. It is specially developed for the Intel N3000 NIC. Since it
is an FPGA based card, it is designed for the users to runtime reload
part of the MAC layer logic developed by themselves, while the ETH GROUP
is another part of the MAC which is not expected to be reloaded by
customers, but it provides some configurations for software to work with
the user logic.
So I catagory the feature as the devices that "designed for specific
purposes and does not fit into one of the standard kernel subsystems".
Some related description could be found in Patch #2, to illustrate why
using UIO for some DFL devices.
>
> And why can't you use the existing UIO drivers that bind to memory
There are now UIO drivers for PCI or platform devices, but in this case
we are going to export a DFL(Device Feature List) bus device to
userspace, a DFL driver for UIO is needed to bind to it.
> regions specified by firmware? Without an interrupt being used, why is
> UIO needed at all?
This DFL UIO driver could exports the MMIO of a DFL device to users for
direct access. This is enough for the only ETH GROUP feature been fully
controlled by user since it supports no interrupt.
The memory regions for DFL devices are enumerated by DFL core according to
the Device Feature List info on hardware, not specified by firmware tables.
People may also use /dev/mem, but they have no knowledge of the memory base
of the DFL device they want.
Some DFL features support interrupts but they are handled by kernel drivers.
We may add interrupt support for the DFL UIO driver when it is to support
a new DFL feature with interrupts.
Thanks,
Yilun
Hi Greg,
On Sat, Feb 27, 2021 at 04:42:55PM +0100, Greg KH wrote:
> On Sat, Feb 27, 2021 at 11:27:03PM +0800, Xu Yilun wrote:
> > This patch supports the DFL drivers be written in userspace. This is
> > realized by exposing the userspace I/O device interfaces.
> >
> > The driver now only binds the ether group feature, which has no irq. So
> > the irq support is not implemented yet.
> >
> > Signed-off-by: Xu Yilun <[email protected]>
> > Reviewed-by: Tom Rix <[email protected]>
> > ---
> > v9: switch to add a uio driver in drivers/uio
> > v10: add the source file in MAINTAINERS
> > more descriptive Kconfig header
> > add detailed path for opae uio example
> > v11: no change
> > ---
> > MAINTAINERS | 1 +
> > drivers/uio/Kconfig | 17 +++++++++++++
> > drivers/uio/Makefile | 1 +
> > drivers/uio/uio_dfl.c | 66 +++++++++++++++++++++++++++++++++++++++++++++++++++
> > 4 files changed, 85 insertions(+)
> > create mode 100644 drivers/uio/uio_dfl.c
> >
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 000fe0b..4dc0354 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -6943,6 +6943,7 @@ S: Maintained
> > F: Documentation/ABI/testing/sysfs-bus-dfl*
> > F: Documentation/fpga/dfl.rst
> > F: drivers/fpga/dfl*
> > +F: drivers/uio/uio_dfl.c
> > F: include/linux/dfl.h
> > F: include/uapi/linux/fpga-dfl.h
> >
> > diff --git a/drivers/uio/Kconfig b/drivers/uio/Kconfig
> > index 202ee81..5531f3a 100644
> > --- a/drivers/uio/Kconfig
> > +++ b/drivers/uio/Kconfig
> > @@ -165,4 +165,21 @@ config UIO_HV_GENERIC
> > to network and storage devices from userspace.
> >
> > If you compile this as a module, it will be called uio_hv_generic.
> > +
> > +config UIO_DFL
> > + tristate "Generic driver for DFL (Device Feature List) bus"
> > + depends on FPGA_DFL
> > + help
> > + Generic DFL (Device Feature List) driver for Userspace I/O devices.
> > + It is useful to provide direct access to DFL devices from userspace.
> > + A sample userspace application using this driver is available for
> > + download in a git repository:
> > +
> > + git clone https://github.com/OPAE/opae-sdk.git
> > +
> > + It could be found at:
> > +
> > + opae-sdk/tools/libopaeuio/
> > +
> > + If you compile this as a module, it will be called uio_dfl.
> > endif
> > diff --git a/drivers/uio/Makefile b/drivers/uio/Makefile
> > index c285dd2..f2f416a1 100644
> > --- a/drivers/uio/Makefile
> > +++ b/drivers/uio/Makefile
> > @@ -11,3 +11,4 @@ obj-$(CONFIG_UIO_PRUSS) += uio_pruss.o
> > obj-$(CONFIG_UIO_MF624) += uio_mf624.o
> > obj-$(CONFIG_UIO_FSL_ELBC_GPCM) += uio_fsl_elbc_gpcm.o
> > obj-$(CONFIG_UIO_HV_GENERIC) += uio_hv_generic.o
> > +obj-$(CONFIG_UIO_DFL) += uio_dfl.o
> > diff --git a/drivers/uio/uio_dfl.c b/drivers/uio/uio_dfl.c
> > new file mode 100644
> > index 0000000..89c0fc7
> > --- /dev/null
> > +++ b/drivers/uio/uio_dfl.c
> > @@ -0,0 +1,66 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Generic DFL driver for Userspace I/O devicess
> > + *
> > + * Copyright (C) 2021 Intel Corporation, Inc.
> > + */
> > +#include <linux/dfl.h>
> > +#include <linux/errno.h>
> > +#include <linux/module.h>
> > +#include <linux/uio_driver.h>
> > +
> > +#define DRIVER_NAME "uio_dfl"
> > +
> > +static int uio_dfl_probe(struct dfl_device *ddev)
> > +{
> > + struct resource *r = &ddev->mmio_res;
> > + struct device *dev = &ddev->dev;
> > + struct uio_info *uioinfo;
> > + struct uio_mem *uiomem;
> > + int ret;
> > +
> > + uioinfo = devm_kzalloc(dev, sizeof(struct uio_info), GFP_KERNEL);
> > + if (!uioinfo)
> > + return -ENOMEM;
> > +
> > + uioinfo->name = DRIVER_NAME;
> > + uioinfo->version = "0";
> > +
> > + uiomem = &uioinfo->mem[0];
> > + uiomem->memtype = UIO_MEM_PHYS;
> > + uiomem->addr = r->start & PAGE_MASK;
> > + uiomem->offs = r->start & ~PAGE_MASK;
> > + uiomem->size = (uiomem->offs + resource_size(r)
> > + + PAGE_SIZE - 1) & PAGE_MASK;
> > + uiomem->name = r->name;
> > +
> > + /* Irq is yet to be supported */
> > + uioinfo->irq = UIO_IRQ_NONE;
> > +
> > + ret = devm_uio_register_device(dev, uioinfo);
> > + if (ret)
> > + dev_err(dev, "unable to register uio device\n");
> > +
> > + return ret;
> > +}
> > +
> > +#define FME_FEATURE_ID_ETH_GROUP 0x10
>
> Why are you saying that an ethernet driver should be using the UIO
> interface?
>
> And why can't you use the existing UIO drivers that bind to memory
> regions specified by firmware? Without an interrupt being used, why is
> UIO needed at all?
That was an earlier version -- which from your comments you didn't seem
to like :) Maybe miscommunication.
Essentially I see two options:
- Have a DFL bus driver instantiate a platform driver (uio_pdrv_genirq)
which I *think* you described above?
- What this patch implements -- a UIO driver on the DFL bus
These FPGA devices can on the fly change their contents and -- even if
just for test -- being able to expose a bunch of registers via UIO can
be extremely useful.
Whether a device should expose registers or not should be up to the
implemeneter of the FPGA design I think (policy). This patch (or the
previous version) provides a mechanism to do so via DFL.
This is similar in nature to uio_pdrv_genirq on a DT based platform, to
expose the registers you instantiate the DT node.
Re-implementing a new driver for each of these instances doesn't seem
desirable and tying DFL as enumeration mechanism to UIO seems like a
good compromise for enabling this kind of functionality.
Note this is *not* an attempt to bypass the network stack or other
existing subsystems.
Cheers,
Moritz