Re: [PATCH] fpga: fpga-mgr: move compat_id from fpga_mgr to dfl

[Moritz Fischer <mdf@kernel.org>]

Hi Tom,

On Wed, Jul 07, 2021 at 01:09:02PM -0700, trix@redhat.com wrote:
> From: Tom Rix <trix@redhat.com>
> 
> fpga_mgr's element compat_id is only used by dfl.
> Implementation specific data should not be stored
> in common structures.  So move it to dfl.
> 
> dfl_fme_mgr reads its compat_id register and makes a copy.
> dfl_fme_region reads dfl_fme_mgr's value and makes a copy,
> then region outputs the value to sysfs.  There is no other
> use.  Instead of making copies and passing them around, output
> the compat_id directly in dfl_fme_mgr.
> 
> The sysfs change is from
> /sys/class/fpga_region/region0/compat_id
> to
> /sys/class/fpga_region/region0/dfl-fme.0/dfl-fme-mgr.0/compat_id

NAK. We can't change ABI like that.

> 
> Signed-off-by: Tom Rix <trix@redhat.com>
> ---
>  .../ABI/testing/sysfs-class-fpga-region       |  9 -----
>  Documentation/fpga/dfl.rst                    |  2 +-
>  drivers/fpga/dfl-fme-mgr.c                    | 34 ++++++++++++-------
>  drivers/fpga/dfl-fme-region.c                 |  1 -
>  drivers/fpga/fpga-region.c                    | 22 ------------
>  include/linux/fpga/fpga-mgr.h                 | 13 -------
>  include/linux/fpga/fpga-region.h              |  2 --
>  7 files changed, 22 insertions(+), 61 deletions(-)
>  delete mode 100644 Documentation/ABI/testing/sysfs-class-fpga-region
> 
> diff --git a/Documentation/ABI/testing/sysfs-class-fpga-region b/Documentation/ABI/testing/sysfs-class-fpga-region
> deleted file mode 100644
> index bc7ec644acc9..000000000000
> --- a/Documentation/ABI/testing/sysfs-class-fpga-region
> +++ /dev/null
> @@ -1,9 +0,0 @@
> -What:		/sys/class/fpga_region/<region>/compat_id
> -Date:		June 2018
> -KernelVersion:	4.19
> -Contact:	Wu Hao <hao.wu@intel.com>
> -Description:	FPGA region id for compatibility check, e.g. compatibility
> -		of the FPGA reconfiguration hardware and image. This value
> -		is defined or calculated by the layer that is creating the
> -		FPGA region. This interface returns the compat_id value or
> -		just error code -ENOENT in case compat_id is not used.
> diff --git a/Documentation/fpga/dfl.rst b/Documentation/fpga/dfl.rst
> index 75df90d1e54c..bca36060de29 100644
> --- a/Documentation/fpga/dfl.rst
> +++ b/Documentation/fpga/dfl.rst
> @@ -246,7 +246,7 @@ generated for the exact static FPGA region and targeted reconfigurable region
>  (port) of the FPGA, otherwise, the reconfiguration operation will fail and
>  possibly cause system instability. This compatibility can be checked by
>  comparing the compatibility ID noted in the header of PR bitstream file against
> -the compat_id exposed by the target FPGA region. This check is usually done by
> +the compat_id exposed by the target FME. This check is usually done by
>  userspace before calling the reconfiguration IOCTL.
>  
>  
> diff --git a/drivers/fpga/dfl-fme-mgr.c b/drivers/fpga/dfl-fme-mgr.c
> index d5861d13b306..62d558b44ae6 100644
> --- a/drivers/fpga/dfl-fme-mgr.c
> +++ b/drivers/fpga/dfl-fme-mgr.c
> @@ -272,17 +272,31 @@ static const struct fpga_manager_ops fme_mgr_ops = {
>  	.status = fme_mgr_status,
>  };
>  
> -static void fme_mgr_get_compat_id(void __iomem *fme_pr,
> -				  struct fpga_compat_id *id)
> +static ssize_t compat_id_show(struct device *dev,
> +			      struct device_attribute *attr, char *buf)
>  {
> -	id->id_l = readq(fme_pr + FME_PR_INTFC_ID_L);
> -	id->id_h = readq(fme_pr + FME_PR_INTFC_ID_H);
> +	struct dfl_fme_mgr_pdata *pdata = dev_get_platdata(dev);
> +	u64 l, h;
> +
> +	l = readq(pdata->ioaddr + FME_PR_INTFC_ID_L);
> +	h = readq(pdata->ioaddr + FME_PR_INTFC_ID_H);
> +
> +	return sysfs_emit(buf, "%016llx%016llx\n",
> +			  (unsigned long long)h,
> +			  (unsigned long long)l);
>  }
>  
> +static DEVICE_ATTR_RO(compat_id);
> +
> +static struct attribute *fme_mgr_attrs[] = {
> +	&dev_attr_compat_id.attr,
> +	NULL,
> +};
> +ATTRIBUTE_GROUPS(fme_mgr);
> +
>  static int fme_mgr_probe(struct platform_device *pdev)
>  {
>  	struct dfl_fme_mgr_pdata *pdata = dev_get_platdata(&pdev->dev);
> -	struct fpga_compat_id *compat_id;
>  	struct device *dev = &pdev->dev;
>  	struct fme_mgr_priv *priv;
>  	struct fpga_manager *mgr;
> @@ -300,27 +314,21 @@ static int fme_mgr_probe(struct platform_device *pdev)
>  		priv->ioaddr = devm_ioremap_resource(dev, res);
>  		if (IS_ERR(priv->ioaddr))
>  			return PTR_ERR(priv->ioaddr);
> +		pdata->ioaddr = priv->ioaddr;
>  	}
>  
> -	compat_id = devm_kzalloc(dev, sizeof(*compat_id), GFP_KERNEL);
> -	if (!compat_id)
> -		return -ENOMEM;
> -
> -	fme_mgr_get_compat_id(priv->ioaddr, compat_id);
> -
>  	mgr = devm_fpga_mgr_create(dev, "DFL FME FPGA Manager",
>  				   &fme_mgr_ops, priv);
>  	if (!mgr)
>  		return -ENOMEM;
>  
> -	mgr->compat_id = compat_id;
> -
>  	return devm_fpga_mgr_register(dev, mgr);
>  }
>  
>  static struct platform_driver fme_mgr_driver = {
>  	.driver	= {
>  		.name    = DFL_FPGA_FME_MGR,
> +		.dev_groups = fme_mgr_groups,
>  	},
>  	.probe   = fme_mgr_probe,
>  };
> diff --git a/drivers/fpga/dfl-fme-region.c b/drivers/fpga/dfl-fme-region.c
> index 1eeb42af1012..4825639a3845 100644
> --- a/drivers/fpga/dfl-fme-region.c
> +++ b/drivers/fpga/dfl-fme-region.c
> @@ -46,7 +46,6 @@ static int fme_region_probe(struct platform_device *pdev)
>  	}
>  
>  	region->priv = pdata;
> -	region->compat_id = mgr->compat_id;
>  	platform_set_drvdata(pdev, region);
>  
>  	ret = fpga_region_register(region);
> diff --git a/drivers/fpga/fpga-region.c b/drivers/fpga/fpga-region.c
> index a4838715221f..c971f76ca61a 100644
> --- a/drivers/fpga/fpga-region.c
> +++ b/drivers/fpga/fpga-region.c
> @@ -158,27 +158,6 @@ int fpga_region_program_fpga(struct fpga_region *region)
>  }
>  EXPORT_SYMBOL_GPL(fpga_region_program_fpga);
>  
> -static ssize_t compat_id_show(struct device *dev,
> -			      struct device_attribute *attr, char *buf)
> -{
> -	struct fpga_region *region = to_fpga_region(dev);
> -
> -	if (!region->compat_id)
> -		return -ENOENT;
> -
> -	return sprintf(buf, "%016llx%016llx\n",
> -		       (unsigned long long)region->compat_id->id_h,
> -		       (unsigned long long)region->compat_id->id_l);
> -}
> -
> -static DEVICE_ATTR_RO(compat_id);
> -
> -static struct attribute *fpga_region_attrs[] = {
> -	&dev_attr_compat_id.attr,
> -	NULL,
> -};
> -ATTRIBUTE_GROUPS(fpga_region);
> -
>  /**
>   * fpga_region_create - alloc and init a struct fpga_region
>   * @parent: device parent
> @@ -328,7 +307,6 @@ static int __init fpga_region_init(void)
>  	if (IS_ERR(fpga_region_class))
>  		return PTR_ERR(fpga_region_class);
>  
> -	fpga_region_class->dev_groups = fpga_region_groups;
>  	fpga_region_class->dev_release = fpga_region_dev_release;
>  
>  	return 0;
> diff --git a/include/linux/fpga/fpga-mgr.h b/include/linux/fpga/fpga-mgr.h
> index ec2cd8bfceb0..ebdea215a864 100644
> --- a/include/linux/fpga/fpga-mgr.h
> +++ b/include/linux/fpga/fpga-mgr.h
> @@ -143,24 +143,12 @@ struct fpga_manager_ops {
>  #define FPGA_MGR_STATUS_IP_PROTOCOL_ERR		BIT(3)
>  #define FPGA_MGR_STATUS_FIFO_OVERFLOW_ERR	BIT(4)
>  
> -/**
> - * struct fpga_compat_id - id for compatibility check
> - *
> - * @id_h: high 64bit of the compat_id
> - * @id_l: low 64bit of the compat_id
> - */
> -struct fpga_compat_id {
> -	u64 id_h;
> -	u64 id_l;
> -};
> -
>  /**
>   * struct fpga_manager - fpga manager structure
>   * @name: name of low level fpga manager
>   * @dev: fpga manager device
>   * @ref_mutex: only allows one reference to fpga manager
>   * @state: state of fpga manager
> - * @compat_id: FPGA manager id for compatibility check.
>   * @mops: pointer to struct of fpga manager ops
>   * @priv: low level driver private date
>   */
> @@ -169,7 +157,6 @@ struct fpga_manager {
>  	struct device dev;
>  	struct mutex ref_mutex;
>  	enum fpga_mgr_states state;
> -	struct fpga_compat_id *compat_id;
>  	const struct fpga_manager_ops *mops;
>  	void *priv;
>  };
> diff --git a/include/linux/fpga/fpga-region.h b/include/linux/fpga/fpga-region.h
> index 27cb706275db..b008d5a300fd 100644
> --- a/include/linux/fpga/fpga-region.h
> +++ b/include/linux/fpga/fpga-region.h
> @@ -14,7 +14,6 @@
>   * @bridge_list: list of FPGA bridges specified in region
>   * @mgr: FPGA manager
>   * @info: FPGA image info
> - * @compat_id: FPGA region id for compatibility check.
>   * @priv: private data
>   * @get_bridges: optional function to get bridges to a list
>   */
> @@ -24,7 +23,6 @@ struct fpga_region {
>  	struct list_head bridge_list;
>  	struct fpga_manager *mgr;
>  	struct fpga_image_info *info;
> -	struct fpga_compat_id *compat_id;
>  	void *priv;
>  	int (*get_bridges)(struct fpga_region *region);
>  };
> -- 
> 2.26.3
> 

Thanks,
Moritz