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

[Tom Rix]

On 10/18/20 9:16 PM, Xu Yilun wrote:
> On Fri, Oct 16, 2020 at 09:36:00AM -0700, Tom Rix wrote:
>> On 10/15/20 11:02 PM, 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.
>>>
>>> Signed-off-by: Xu Yilun <yilun.xu@xxxxxxxxx>
>>> ---
>>>  drivers/fpga/Kconfig        | 10 ++++++
>>>  drivers/fpga/Makefile       |  1 +
>>>  drivers/fpga/dfl-uio-pdev.c | 83 +++++++++++++++++++++++++++++++++++++++++++++
>>>  3 files changed, 94 insertions(+)
>>>  create mode 100644 drivers/fpga/dfl-uio-pdev.c
>>>
>>> diff --git a/drivers/fpga/Kconfig b/drivers/fpga/Kconfig
>>> index 5d7f0ae..e054722 100644
>>> --- a/drivers/fpga/Kconfig
>>> +++ b/drivers/fpga/Kconfig
>>> @@ -202,6 +202,16 @@ 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
>>> +	  adds the uio_pdrv_genirq platform device with the DFL device's
>>> +	  resources, and let the generic UIO platform device driver provide
>> 'and lets the'
> Yes.
>
>>> +	  support to 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..e07b3d5 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..d35b846
>>> --- /dev/null
>>> +++ b/drivers/fpga/dfl-uio-pdev.c
>>> @@ -0,0 +1,83 @@
>>> +// 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 device *dev = &ddev->dev;
>>> +	struct platform_device_info pdevinfo = { 0 };
>>> +	struct uio_info uio_pdata = { 0 };
>>> +	struct platform_device *uio_pdev;
>>> +	struct resource *res;
>>> +	int i, idx = 0;
>> idx is not needed.
> I could remove the idx. But I think I could ++res during the resource
> filling.

ok.

You may want to check the code generation, my feeling is ++res will be worse.

Tom

>
> Thanks,
> Yilun
>
>>> +
>>> +	pdevinfo.name = "uio_pdrv_genirq";
>>> +
>>> +	res = kcalloc(ddev->num_irqs + 1, sizeof(*res), GFP_KERNEL);
>>> +	if (!res)
>>> +		return -ENOMEM;
>>> +
>>> +	res[idx].parent = &ddev->mmio_res;
>> res[0].parent =
>>> +	res[idx].flags = IORESOURCE_MEM;
>>> +	res[idx].start = ddev->mmio_res.start;
>>> +	res[idx].end = ddev->mmio_res.end;
>>> +	++idx;
>>> +
>>> +	/* then add irq resource */
>>> +	for (i = 0; i < ddev->num_irqs; i++) {
>>> +		res[idx].flags = IORESOURCE_IRQ;
>> res[i+1].flags =
>>
>> Tom
>>
>>> +		res[idx].start = ddev->irqs[i];
>>> +		res[idx].end = ddev->irqs[i];
>>> +		++idx;
>>> +	}
>>> +
>>> +	uio_pdata.name = DRIVER_NAME;
>>> +	uio_pdata.version = "0";
>>> +
>>> +	pdevinfo.res = res;
>>> +	pdevinfo.num_res = idx;
>>> +	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);
>>> +	if (!IS_ERR(uio_pdev))
>>> +		dev_set_drvdata(dev, uio_pdev);
>>> +
>>> +	kfree(res);
>>> +
>>> +	return PTR_ERR_OR_ZERO(uio_pdev);
>>> +}
>>> +
>>> +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);
>>> +}
>>> +
>>> +static struct dfl_driver dfl_uio_pdev_driver = {
>>> +	.drv	= {
>>> +		.name       = DRIVER_NAME,
>>> +	},
>>> +	.probe	= dfl_uio_pdev_probe,
>>> +	.remove	= dfl_uio_pdev_remove,
>>> +};
>>> +module_dfl_driver(dfl_uio_pdev_driver);
>>> +
>>> +MODULE_DESCRIPTION("DFL driver for Userspace I/O platform devices");
>>> +MODULE_AUTHOR("Intel Corporation");
>>> +MODULE_LICENSE("GPL v2");