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Date:   Tue, 10 Mar 2020 18:39:21 +0800
From:   Wu Hao <hao.wu@intel.com>
To:     Xu Yilun <yilun.xu@intel.com>
Cc:     mdf@kernel.org, linux-fpga@vger.kernel.org,
        linux-kernel@vger.kernel.org, Luwei Kang <luwei.kang@intel.com>
Subject: Re: [PATCH 4/7] fpga: dfl: afu: add interrupt support for error
 reporting
Message-ID: <20200310103921.GD28396@hao-dev>
References: <1583749790-10837-1-git-send-email-yilun.xu@intel.com>
 <1583749790-10837-5-git-send-email-yilun.xu@intel.com>
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On Mon, Mar 09, 2020 at 06:29:47PM +0800, Xu Yilun wrote:
> Error reporting interrupt is very useful to notify users that some
> errors are detected by the hardware. Once users are notified, they
> could query hardware logged error states, no need to continuously
> poll on these states.
> 
> This patch follows the common DFL interrupt notification and handling
> mechanism, implements two ioctl commands below for user to query
> hardware capability, and set/unset interrupt triggers.
> 
>  Ioctls:
>  * DFL_FPGA_PORT_ERR_GET_INFO
>    get error reporting feature info, including num_irqs which is used to
>    determine whether/how many interrupts it supports.
> 
>  * DFL_FPGA_PORT_ERR_SET_IRQ
>    set/unset given eventfds as error interrupt triggers.
> 
> Signed-off-by: Luwei Kang <luwei.kang@intel.com>
> Signed-off-by: Wu Hao <hao.wu@intel.com>
> Signed-off-by: Xu Yilun <yilun.xu@intel.com>
> ---
>  drivers/fpga/dfl-afu-error.c  | 69 +++++++++++++++++++++++++++++++++++++++++++
>  drivers/fpga/dfl-afu-main.c   |  4 +++
>  include/uapi/linux/fpga-dfl.h | 34 +++++++++++++++++++++
>  3 files changed, 107 insertions(+)
> 
> diff --git a/drivers/fpga/dfl-afu-error.c b/drivers/fpga/dfl-afu-error.c
> index c1467ae..a2c5454 100644
> --- a/drivers/fpga/dfl-afu-error.c
> +++ b/drivers/fpga/dfl-afu-error.c
> @@ -15,6 +15,7 @@
>   */
>  
>  #include <linux/uaccess.h>
> +#include <linux/fpga-dfl.h>
>  
>  #include "dfl-afu.h"
>  
> @@ -219,6 +220,73 @@ static void port_err_uinit(struct platform_device *pdev,
>  	afu_port_err_mask(&pdev->dev, true);
>  }
>  
> +static long
> +port_err_get_info(struct platform_device *pdev,
> +		  struct dfl_feature *feature, unsigned long arg)
> +{
> +	struct dfl_fpga_port_err_info info;
> +
> +	info.flags = 0;
> +	info.capability = 0;

as flags and capability are not used at this moment, so actually it only exposes
irq information to user. I understand flags and capability are used for
future extension, but it may not work without argsz, as we never know what
comes next, e.g. a capability requires > 32bit can't fit into this ioctl.
So maybe just a ioctl for IRQ_INFO is enough for now.

How do you think?

> +	info.num_irqs = feature->nr_irqs;
> +
> +	if (copy_to_user((void __user *)arg, &info, sizeof(info)))
> +		return -EFAULT;
> +
> +	return 0;
> +}
> +
> +static long port_err_set_irq(struct platform_device *pdev,
> +			     struct dfl_feature *feature, unsigned long arg)
> +{
> +	struct dfl_feature_platform_data *pdata = dev_get_platdata(&pdev->dev);
> +	struct dfl_fpga_irq_set hdr;
> +	s32 *fds;
> +	long ret;
> +
> +	if (!feature->nr_irqs)
> +		return -ENOENT;
> +
> +	if (copy_from_user(&hdr, (void __user *)arg, sizeof(hdr)))
> +		return -EFAULT;
> +
> +	if (hdr.flags || (hdr.start + hdr.count > feature->nr_irqs) ||
> +	    (hdr.start + hdr.count < hdr.start) || !hdr.count)
> +		return -EINVAL;
> +
> +	fds = memdup_user((void __user *)(arg + sizeof(hdr)),
> +			  hdr.count * sizeof(s32));
> +	if (IS_ERR(fds))
> +		return PTR_ERR(fds);
> +
> +	mutex_lock(&pdata->lock);
> +	ret = dfl_fpga_set_irq_triggers(feature, hdr.start, hdr.count, fds);
> +	mutex_unlock(&pdata->lock);
> +
> +	kfree(fds);
> +	return ret;
> +}
> +
> +static long
> +port_err_ioctl(struct platform_device *pdev, struct dfl_feature *feature,
> +	       unsigned int cmd, unsigned long arg)
> +{
> +	long ret = -ENODEV;
> +
> +	switch (cmd) {
> +	case DFL_FPGA_PORT_ERR_GET_INFO:
> +		ret = port_err_get_info(pdev, feature, arg);
> +		break;
> +	case DFL_FPGA_PORT_ERR_SET_IRQ:
> +		ret = port_err_set_irq(pdev, feature, arg);
> +		break;
> +	default:
> +		dev_dbg(&pdev->dev, "%x cmd not handled", cmd);
> +	}
> +
> +	return ret;
> +}
> +
>  const struct dfl_feature_id port_err_id_table[] = {
>  	{.id = PORT_FEATURE_ID_ERROR,},
>  	{0,}
> @@ -227,4 +295,5 @@ const struct dfl_feature_id port_err_id_table[] = {
>  const struct dfl_feature_ops port_err_ops = {
>  	.init = port_err_init,
>  	.uinit = port_err_uinit,
> +	.ioctl = port_err_ioctl,
>  };
> diff --git a/drivers/fpga/dfl-afu-main.c b/drivers/fpga/dfl-afu-main.c
> index 435bde4..fc8b9cf 100644
> --- a/drivers/fpga/dfl-afu-main.c
> +++ b/drivers/fpga/dfl-afu-main.c
> @@ -577,6 +577,7 @@ static int afu_release(struct inode *inode, struct file *filp)
>  {
>  	struct platform_device *pdev = filp->private_data;
>  	struct dfl_feature_platform_data *pdata;
> +	struct dfl_feature *feature;
>  
>  	dev_dbg(&pdev->dev, "Device File Release\n");
>  
> @@ -586,6 +587,9 @@ static int afu_release(struct inode *inode, struct file *filp)
>  	dfl_feature_dev_use_end(pdata);
>  
>  	if (!dfl_feature_dev_use_count(pdata)) {
> +		dfl_fpga_dev_for_each_feature(pdata, feature)
> +			dfl_fpga_set_irq_triggers(feature, 0,
> +						  feature->nr_irqs, NULL);
>  		__port_reset(pdev);
>  		afu_dma_region_destroy(pdata);
>  	}
> diff --git a/include/uapi/linux/fpga-dfl.h b/include/uapi/linux/fpga-dfl.h
> index ec70a0746..846fc91 100644
> --- a/include/uapi/linux/fpga-dfl.h
> +++ b/include/uapi/linux/fpga-dfl.h
> @@ -151,6 +151,40 @@ struct dfl_fpga_port_dma_unmap {
>  
>  #define DFL_FPGA_PORT_DMA_UNMAP		_IO(DFL_FPGA_MAGIC, DFL_PORT_BASE + 4)
>  
> +/**
> + * DFL_FPGA_PORT_ERR_GET_INFO - _IOR(DFL_FPGA_MAGIC, DFL_PORT_BASE + 5,
> + *						struct dfl_fpga_port_err_info)
> + *
> + * Retrieve information about the fpga port error reporting private feature.
> + * Driver fills the info in provided struct dfl_fpga_port_err_info.
> + * Return: 0 on success, -errno on failure.
> + */
> +struct dfl_fpga_port_err_info {
> +	/* Output */
> +	__u32 flags;		/* Zero for now */
> +	__u32 capability;	/* The capability of port error reporting */
> +	__u32 num_irqs;		/* number of irqs it supports */
> +};
> +
> +#define DFL_FPGA_PORT_ERR_GET_INFO	_IO(DFL_FPGA_MAGIC, DFL_PORT_BASE + 5)
> +
> +/**
> + * DFL_FPGA_PORT_ERR_SET_IRQ - _IOW(DFL_FPGA_MAGIC, DFL_PORT_BASE + 6,
> + *						struct dfl_fpga_irq_set)
> + *
> + * Set fpga port error reporting interrupt trigger if evtfds[n] is valid.
> + * Unset related interrupt trigger if evtfds[n] is a negative value.
> + * Return: 0 on success, -errno on failure.
> + */
> +struct dfl_fpga_irq_set {
> +	__u32 flags;		/* Zero for now */
> +	__u32 start;		/* First irq number */
> +	__u32 count;		/* The number of eventfd handler */
> +	__s32 evtfds[];		/* Eventfd handler */
> +};
> +
> +#define DFL_FPGA_PORT_ERR_SET_IRQ	_IO(DFL_FPGA_MAGIC, DFL_PORT_BASE + 6)
> +
>  /* IOCTLs for FME file descriptor */
>  
>  /**
> -- 
> 2.7.4