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Date:   Wed, 11 Mar 2020 00:47:38 +0800
From:   Xu Yilun <yilun.xu@intel.com>
To:     Wu Hao <hao.wu@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: <20200310164738.GC30868@yilunxu-OptiPlex-7050>
References: <1583749790-10837-1-git-send-email-yilun.xu@intel.com>
 <1583749790-10837-5-git-send-email-yilun.xu@intel.com>
 <20200310103921.GD28396@hao-dev>
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On Tue, Mar 10, 2020 at 06:39:21PM +0800, Wu Hao wrote:
> 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?

Yes the flags & capability are for future extension.

The capability field is planned to a bitmask, each bit could indicate the feature
has some capability or not. So it could describe up to 32 capabilities.
I think it would be enough for one sub feature.

With this field, users could get a general description of capabilities with one
ioctl. If some capability has more detailed info, we may add addtional ioctl to
fetch it. This is how it works without argsz. Does it make sense?

And same definition for flag field. The flag fields could contain some
bool running state represented by each bit.

> 
> > +	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