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Date:   Mon, 7 Dec 2020 11:49:51 +0800
From:   Xu Yilun <yilun.xu@...el.com>
To:     trix@...hat.com
Cc:     gregkh@...uxfoundation.org, hao.wu@...el.com, mdf@...nel.org,
        linux-kernel@...r.kernel.org, linux-fpga@...r.kernel.org
Subject: Re: [RFC] fpga: dfl: a prototype uio driver

On Sun, Dec 06, 2020 at 01:55:54PM -0800, trix@...hat.com wrote:
> From: Tom Rix <trix@...hat.com>
> 
> >From [PATCH 0/2] UIO support for dfl devices
> https://lore.kernel.org/linux-fpga/1602828151-24784-1-git-send-email-yilun.xu@intel.com/
> 
> Here is an idea to have uio support with no driver override.
> 
> This makes UIO the primary driver interface because every feature
> will have one and makes the existing platform driver interface
> secondary.  There will be a new burden for locking write access when
> they compete.
> 
> Example shows finding the fpga's temperture.

Hi Tom:

Thanks for the idea and detailed illustrate with the patch. I see it
abandons the driver_override and expose all the DFL devices to userspace
by UIO. I'd like to see if we could get some more comments on it.

Thanks,
Yilun

> 
> Signed-off-by: Tom Rix <trix@...hat.com>
> ---
>  drivers/fpga/dfl-fme-main.c |  9 +++-
>  drivers/fpga/dfl-uio.c      | 96 +++++++++++++++++++++++++++++++++++++
>  drivers/fpga/dfl.c          | 44 ++++++++++++++++-
>  drivers/fpga/dfl.h          |  9 ++++
>  uio.c                       | 56 ++++++++++++++++++++++
>  5 files changed, 212 insertions(+), 2 deletions(-)
>  create mode 100644 drivers/fpga/dfl-uio.c
>  create mode 100644 uio.c
> 
> diff --git a/drivers/fpga/dfl-fme-main.c b/drivers/fpga/dfl-fme-main.c
> index 037dc4f946f0..3323e90a18c4 100644
> --- a/drivers/fpga/dfl-fme-main.c
> +++ b/drivers/fpga/dfl-fme-main.c
> @@ -709,12 +709,18 @@ static int fme_probe(struct platform_device *pdev)
>  	if (ret)
>  		goto dev_destroy;
>  
> -	ret = dfl_fpga_dev_ops_register(pdev, &fme_fops, THIS_MODULE);
> +	ret = dfl_fpga_dev_feature_init_uio(pdev, DFH_TYPE_FIU);
>  	if (ret)
>  		goto feature_uinit;
>  
> +	ret = dfl_fpga_dev_ops_register(pdev, &fme_fops, THIS_MODULE);
> +	if (ret)
> +		goto feature_uinit_uio;
> +
>  	return 0;
>  
> +feature_uinit_uio:
> +	dfl_fpga_dev_feature_uinit_uio(pdev, DFH_TYPE_FIU);
>  feature_uinit:
>  	dfl_fpga_dev_feature_uinit(pdev);
>  dev_destroy:
> @@ -726,6 +732,7 @@ exit:
>  static int fme_remove(struct platform_device *pdev)
>  {
>  	dfl_fpga_dev_ops_unregister(pdev);
> +	dfl_fpga_dev_feature_uinit_uio(pdev, DFH_TYPE_FIU);
>  	dfl_fpga_dev_feature_uinit(pdev);
>  	fme_dev_destroy(pdev);
>  
> diff --git a/drivers/fpga/dfl-uio.c b/drivers/fpga/dfl-uio.c
> new file mode 100644
> index 000000000000..7610ee0b19dc
> --- /dev/null
> +++ b/drivers/fpga/dfl-uio.c
> @@ -0,0 +1,96 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * prototype dfl uio driver
> + *
> + * Copyright Tom Rix 2020
> + */
> +#include <linux/module.h>
> +#include "dfl.h"
> +
> +static irqreturn_t dfl_uio_handler(int irq, struct uio_info *info)
> +{
> +	return IRQ_HANDLED;
> +}
> +
> +static int dfl_uio_mmap(struct uio_info *info, struct vm_area_struct *vma)
> +{
> +	int ret = -ENODEV;
> +	return ret;
> +}
> +
> +static int dfl_uio_open(struct uio_info *info, struct inode *inode)
> +{
> +	int ret = -ENODEV;
> +	struct dfl_feature *feature = container_of(info, struct dfl_feature, uio);
> +	if (feature->dev)
> +		mutex_lock(&feature->lock);
> +
> +	ret = 0;
> +	return ret;
> +}
> +
> +static int dfl_uio_release(struct uio_info *info, struct inode *inode)
> +{
> +	int ret = -ENODEV;
> +	struct dfl_feature *feature = container_of(info, struct dfl_feature, uio);
> +	if (feature->dev)
> +		mutex_unlock(&feature->lock);
> +
> +	ret = 0;
> +	return ret;
> +}
> +
> +static int dfl_uio_irqcontrol(struct uio_info *info, s32 irq_on)
> +{
> +	int ret = -ENODEV;
> +	return ret;
> +}
> +
> +int dfl_uio_add(struct dfl_feature *feature)
> +{
> +	struct uio_info *uio = &feature->uio;
> +	struct resource *res =
> +		&feature->dev->resource[feature->resource_index];
> +	int ret = 0;
> +
> +	uio->name = kasprintf(GFP_KERNEL, "dfl-uio-%llx", feature->id);
> +	if (!uio->name) {
> +		ret = -ENOMEM;
> +		goto exit;
> +	}
> +
> +	uio->version = "0.1";
> +	uio->mem[0].memtype = UIO_MEM_PHYS;
> +	uio->mem[0].addr = res->start & PAGE_MASK;
> +	uio->mem[0].offs = res->start & ~PAGE_MASK;
> +	uio->mem[0].size = (uio->mem[0].offs + resource_size(res)
> +			    + PAGE_SIZE - 1) & PAGE_MASK;
> +	/* How are nr_irqs > 1 handled ??? */
> +	if (feature->nr_irqs == 1)
> +		uio->irq = feature->irq_ctx[0].irq;
> +	uio->handler = dfl_uio_handler;
> +	//uio->mmap = dfl_uio_mmap;
> +	uio->open = dfl_uio_open;
> +	uio->release = dfl_uio_release;
> +	uio->irqcontrol = dfl_uio_irqcontrol;
> +
> +	ret = uio_register_device(&feature->dev->dev, uio);
> +	if (ret)
> +		goto err_register;
> +
> +exit:
> +	return ret;
> +err_register:
> +	kfree(uio->name);
> +	goto exit;
> +}
> +EXPORT_SYMBOL_GPL(dfl_uio_add);
> +
> +int dfl_uio_remove(struct dfl_feature *feature)
> +{
> +	uio_unregister_device(&feature->uio);
> +	kfree(feature->uio.name);
> +	return 0;
> +}
> +EXPORT_SYMBOL_GPL(dfl_uio_remove);
> +
> diff --git a/drivers/fpga/dfl.c b/drivers/fpga/dfl.c
> index 1305be48037d..af2cd3d1b5f6 100644
> --- a/drivers/fpga/dfl.c
> +++ b/drivers/fpga/dfl.c
> @@ -603,6 +603,7 @@ static int dfl_feature_instance_init(struct platform_device *pdev,
>  	}
>  
>  	feature->ops = drv->ops;
> +	mutex_init(&feature->lock);
>  
>  	return ret;
>  }
> @@ -663,10 +664,51 @@ exit:
>  }
>  EXPORT_SYMBOL_GPL(dfl_fpga_dev_feature_init);
>  
> +int dfl_fpga_dev_feature_init_uio(struct platform_device *pdev, int dfh_type) {
> +	struct dfl_feature_platform_data *pdata = dev_get_platdata(&pdev->dev);
> +	struct dfl_feature *feature;
> +	int ret;
> +
> +	dfl_fpga_dev_for_each_feature(pdata, feature) {
> +		if (dfh_type == DFH_TYPE_FIU) {
> +			if (feature->id == FEATURE_ID_FIU_HEADER ||
> +			    feature->id == FEATURE_ID_AFU)
> +			    continue;
> +
> +			ret = dfl_uio_add(feature);
> +			if (ret)
> +				goto exit;
> +		}
> +	}
> +
> +	return 0;
> +exit:
> +	dfl_fpga_dev_feature_uinit_uio(pdev, dfh_type);
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(dfl_fpga_dev_feature_init_uio);
> +
> +int dfl_fpga_dev_feature_uinit_uio(struct platform_device *pdev, int dfh_type) {
> +	struct dfl_feature_platform_data *pdata = dev_get_platdata(&pdev->dev);
> +	struct dfl_feature *feature;
> +	int ret = 0;
> +
> +	dfl_fpga_dev_for_each_feature(pdata, feature) {
> +		if (dfh_type == DFH_TYPE_FIU) {
> +			if (feature->id == FEATURE_ID_FIU_HEADER ||
> +			    feature->id == FEATURE_ID_AFU)
> +				continue;
> +
> +			ret |= dfl_uio_remove(feature);
> +		}
> +	}
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(dfl_fpga_dev_feature_uinit_uio);
> +
>  static void dfl_chardev_uinit(void)
>  {
>  	int i;
> -
>  	for (i = 0; i < DFL_FPGA_DEVT_MAX; i++)
>  		if (MAJOR(dfl_chrdevs[i].devt)) {
>  			unregister_chrdev_region(dfl_chrdevs[i].devt,
> diff --git a/drivers/fpga/dfl.h b/drivers/fpga/dfl.h
> index a85d1cd7a130..fde0fc902d4d 100644
> --- a/drivers/fpga/dfl.h
> +++ b/drivers/fpga/dfl.h
> @@ -26,6 +26,7 @@
>  #include <linux/platform_device.h>
>  #include <linux/slab.h>
>  #include <linux/uuid.h>
> +#include <linux/uio_driver.h>
>  #include <linux/fpga/fpga-region.h>
>  
>  /* maximum supported number of ports */
> @@ -232,6 +233,7 @@ struct dfl_feature_irq_ctx {
>   * struct dfl_feature - sub feature of the feature devices
>   *
>   * @dev: ptr to pdev of the feature device which has the sub feature.
> + * @uio: uio interface for feature.
>   * @id: sub feature id.
>   * @index: unique identifier for an sub feature within the feature device.
>   *	   It is possible that multiply sub features with same feature id are
> @@ -248,6 +250,8 @@ struct dfl_feature_irq_ctx {
>   */
>  struct dfl_feature {
>  	struct platform_device *dev;
> +	struct uio_info uio;
> +	struct mutex lock; /* serialize dev and uio */
>  	u64 id;
>  	int index;
>  	int resource_index;
> @@ -360,6 +364,11 @@ void dfl_fpga_dev_feature_uinit(struct platform_device *pdev);
>  int dfl_fpga_dev_feature_init(struct platform_device *pdev,
>  			      struct dfl_feature_driver *feature_drvs);
>  
> +int dfl_fpga_dev_feature_init_uio(struct platform_device *pdev, int dfh_type);
> +int dfl_fpga_dev_feature_uinit_uio(struct platform_device *pdev, int dfh_type);
> +int dfl_uio_add(struct dfl_feature *feature);
> +int dfl_uio_remove(struct dfl_feature *feature);
> +
>  int dfl_fpga_dev_ops_register(struct platform_device *pdev,
>  			      const struct file_operations *fops,
>  			      struct module *owner);
> diff --git a/uio.c b/uio.c
> new file mode 100644
> index 000000000000..50210aab4822
> --- /dev/null
> +++ b/uio.c
> @@ -0,0 +1,56 @@
> +#include <stdlib.h>
> +#include <stdio.h>
> +#include <unistd.h>
> +#include <sys/mman.h>
> +#include <sys/types.h>
> +#include <sys/stat.h>
> +#include <fcntl.h>
> +#include <errno.h>
> +#include <stdint.h>
> +
> +int main()
> +{
> +	int fd;
> +	uint64_t *ptr;
> +	unsigned page_size=sysconf(_SC_PAGESIZE);
> +	struct stat sb;
> +
> +	/*
> +	 * this is fid 1, thermal mgt
> +	 * ex/ 
> +	 * # cat /sys/class/hwmon/hwmon3/temp1_input
> +	 * 39000
> +	 */
> +	fd = open("/dev/uio0", O_RDONLY|O_SYNC);
> +	if (fd < 0) {
> +		perror("uio open:");
> +		return errno;
> +	}
> +
> +	ptr = (uint64_t *) mmap(NULL, page_size, PROT_READ, MAP_SHARED, fd, 0);
> +	if (!ptr) {
> +		perror("uio mmap:");
> +	} else {
> +
> +		/* from dfl-fme-main.c :
> +		 * 
> +		 * #define FME_THERM_RDSENSOR_FMT1	0x10
> +		 * #define FPGA_TEMPERATURE	GENMASK_ULL(6, 0)
> +		 *
> +		 * case hwmon_temp_input:
> +		 * v = readq(feature->ioaddr + FME_THERM_RDSENSOR_FMT1);
> +		 * *val = (long)(FIELD_GET(FPGA_TEMPERATURE, v) * 1000);
> +		 * break;
> +		 */
> +		uint64_t v = ptr[2];
> +		v &= (1 << 6) -1;
> +		v *= 1000;
> +		printf("Temperature %d\n", v);
> +	    
> +		munmap(ptr, page_size);
> +	}
> +	if (close(fd))
> +		perror("uio close:");
> +
> +	return errno;
> +}
> -- 
> 2.18.4

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