Re: [PATCH v6 1/2] fpga: dfl: add the userspace I/O device support for DFL devices

[Xu Yilun]

On Sat, Jan 16, 2021 at 07:56:08PM -0800, Moritz Fischer wrote:
> Hi Xu,
> 
> On Wed, Jan 13, 2021 at 09:54:07AM +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 leverages the uio_pdrv_genirq, it adds the uio_pdrv_genirq
> > platform device with the DFL device's resources, and let the generic UIO
> > platform device driver provide support to userspace access to kernel
> > interrupts and memory locations.
> > 
> > The driver now supports the ether group feature. To support a new DFL
> > feature been directly accessed via UIO, its feature id should be added to
> > the driver's id_table.
> > 
> > Signed-off-by: Xu Yilun <yilun.xu@xxxxxxxxx>
> > Reviewed-by: Tom Rix <trix@xxxxxxxxxx>
> > Acked-by: Wu Hao <hao.wu@xxxxxxxxx>
> > ---
> > v2: 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.
> >     fix some comments.
> > v3: split the dfl.c changes out of this patch.
> >     some minor fixes
> > v4: drop the idea of a generic matching algorithem, instead we specify
> >      each matching device in id_table.
> >     to make clear that only one irq is supported, the irq handling code
> >      is refactored.
> > v5: refactor the irq resource code.
> > v6: fix the res[] zero initialization issue.
> >     improve the return code for probe().
> > ---
> >  drivers/fpga/Kconfig        | 10 +++++
> >  drivers/fpga/Makefile       |  1 +
> >  drivers/fpga/dfl-uio-pdev.c | 93 +++++++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 104 insertions(+)
> >  create mode 100644 drivers/fpga/dfl-uio-pdev.c
> > 
> > diff --git a/drivers/fpga/Kconfig b/drivers/fpga/Kconfig
> > index 5ff9438..61445be 100644
> > --- a/drivers/fpga/Kconfig
> > +++ b/drivers/fpga/Kconfig
> > @@ -203,6 +203,16 @@ config FPGA_DFL_NIOS_INTEL_PAC_N3000
> >  	  the card. It also instantiates the SPI master (spi-altera) for
> >  	  the card's BMC (Board Management Controller).
> >  
> > +config FPGA_DFL_UIO_PDEV
> > +	tristate "FPGA DFL Driver for Userspace I/O platform devices"
> > +	depends on FPGA_DFL && UIO_PDRV_GENIRQ
> > +	help
> > +	  Enable this to allow some DFL drivers be written in userspace. It
> Nit: Enable this to allow DFL drivers to be written in userspace.

Yes, will fix it.

> > +	  adds the uio_pdrv_genirq platform device with the DFL feature's
> > +	  resources, and lets the generic UIO platform device driver provide
> > +	  support for userspace access to kernel interrupts and memory
> > +	  locations.
> > +
> >  config FPGA_DFL_PCI
> >  	tristate "FPGA DFL PCIe Device Driver"
> >  	depends on PCI && FPGA_DFL
> > diff --git a/drivers/fpga/Makefile b/drivers/fpga/Makefile
> > index 18dc9885..8847fe0 100644
> > --- a/drivers/fpga/Makefile
> > +++ b/drivers/fpga/Makefile
> > @@ -45,6 +45,7 @@ dfl-afu-objs := dfl-afu-main.o dfl-afu-region.o dfl-afu-dma-region.o
> >  dfl-afu-objs += dfl-afu-error.o
> >  
> >  obj-$(CONFIG_FPGA_DFL_NIOS_INTEL_PAC_N3000)	+= dfl-n3000-nios.o
> > +obj-$(CONFIG_FPGA_DFL_UIO_PDEV)		+= dfl-uio-pdev.o
> >  
> >  # Drivers for FPGAs which implement DFL
> >  obj-$(CONFIG_FPGA_DFL_PCI)		+= dfl-pci.o
> > diff --git a/drivers/fpga/dfl-uio-pdev.c b/drivers/fpga/dfl-uio-pdev.c
> > new file mode 100644
> > index 0000000..12b47bf
> > --- /dev/null
> > +++ b/drivers/fpga/dfl-uio-pdev.c
> > @@ -0,0 +1,93 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * DFL driver for Userspace I/O platform devices
> > + *
> > + * Copyright (C) 2020 Intel Corporation, Inc.
> > + */
> > +#include <linux/dfl.h>
> > +#include <linux/errno.h>
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/slab.h>
> > +#include <linux/uio_driver.h>
> > +
> > +#define DRIVER_NAME "dfl-uio-pdev"
> > +
> > +static int dfl_uio_pdev_probe(struct dfl_device *ddev)
> > +{
> > +	struct platform_device_info pdevinfo = { 0 };
> > +	struct resource res[2] = { { 0 } };
> > +	struct uio_info uio_pdata = { 0 };
> > +	struct platform_device *uio_pdev;
> > +	struct device *dev = &ddev->dev;
> > +	unsigned int num_res = 1;
> > +
> > +	res[0].parent = &ddev->mmio_res;
> > +	res[0].flags = IORESOURCE_MEM;
> > +	res[0].start = ddev->mmio_res.start;
> > +	res[0].end = ddev->mmio_res.end;
> > +
> > +	if (ddev->num_irqs) {
> > +		if (ddev->num_irqs > 1)
> > +			dev_warn(&ddev->dev,
> > +				 "%d irqs for %s, but UIO only supports the first one\n",
> > +				 ddev->num_irqs, dev_name(&ddev->dev));
> > +
> > +		res[1].flags = IORESOURCE_IRQ;
> > +		res[1].start = ddev->irqs[0];
> > +		res[1].end = ddev->irqs[0];
> > +		num_res++;
> > +	}
> > +
> > +	uio_pdata.name = DRIVER_NAME;
> > +	uio_pdata.version = "0";
> > +
> > +	pdevinfo.name = "uio_pdrv_genirq";
> > +	pdevinfo.res = res;
> > +	pdevinfo.num_res = num_res;
> > +	pdevinfo.parent = &ddev->dev;
> > +	pdevinfo.id = PLATFORM_DEVID_AUTO;
> > +	pdevinfo.data = &uio_pdata;
> > +	pdevinfo.size_data = sizeof(uio_pdata);
> > +
> > +	uio_pdev = platform_device_register_full(&pdevinfo);
> It looks like:
> 	platform_device_register_resndata(&ddev->dev, "uio_pdrv_genirq",
> 					  PLATFORM_DEVID_AUTO, res, num_res,
> 					  &uio_pdata, sizeof(uio_pdata))
> 
> would work?

It works. I'll change it.

> 
> 
> > +	if (IS_ERR(uio_pdev))
> > +		return PTR_ERR(uio_pdev);
> > +
> > +	dev_set_drvdata(dev, uio_pdev);
> > +
> > +	return 0;
> > +}
> > +
> > +static void dfl_uio_pdev_remove(struct dfl_device *ddev)
> > +{
> > +	struct platform_device *uio_pdev = dev_get_drvdata(&ddev->dev);
> > +
> > +	platform_device_unregister(uio_pdev);
> > +}
> > +
> > +#define FME_FEATURE_ID_ETH_GROUP	0x10
> > +
> > +static const struct dfl_device_id dfl_uio_pdev_ids[] = {
> > +	{ FME_ID, FME_FEATURE_ID_ETH_GROUP },
> > +
> > +	/* Add your new id entries here to support uio for more dfl features */
> This is fairly common, we can maybe drop this comment?

Yes.

Thanks,
Yilun