linux-kernel - RE: [PATCH v2 3/4] fpga: dfl: implement the compat_id

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Message-ID: <DM6PR11MB381991CB430F222FE05EE88D85159@DM6PR11MB3819.namprd11.prod.outlook.com>
Date:   Mon, 12 Jul 2021 01:27:51 +0000
From:   "Wu, Hao" <hao.wu@...el.com>
To:     "trix@...hat.com" <trix@...hat.com>,
        "mdf@...nel.org" <mdf@...nel.org>,
        "corbet@....net" <corbet@....net>
CC:     "linux-fpga@...r.kernel.org" <linux-fpga@...r.kernel.org>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v2 3/4] fpga: dfl: implement the compat_id_show region op

> Subject: [PATCH v2 3/4] fpga: dfl: implement the compat_id_show region op
> 
> From: Tom Rix <trix@...hat.com>
> 
> Make sure dfl will work as previously when compat_id is removed
> from struct fpga_manager.  Store and pass the compat_id values
> internal to dfl.
> 
> Signed-off-by: Tom Rix <trix@...hat.com>
> ---
>  drivers/fpga/dfl-fme-mgr.c    | 16 +++++++++++++---
>  drivers/fpga/dfl-fme-region.c | 14 ++++++++++++++
>  drivers/fpga/dfl.h            | 14 ++++++++++++++
>  3 files changed, 41 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/fpga/dfl-fme-mgr.c b/drivers/fpga/dfl-fme-mgr.c
> index d5861d13b3069..cd0b9157ea6e5 100644
> --- a/drivers/fpga/dfl-fme-mgr.c
> +++ b/drivers/fpga/dfl-fme-mgr.c
> @@ -22,6 +22,7 @@
>  #include <linux/io-64-nonatomic-lo-hi.h>
>  #include <linux/fpga/fpga-mgr.h>
> 
> +#include "dfl.h"
>  #include "dfl-fme-pr.h"
> 
>  /* FME Partial Reconfiguration Sub Feature Register Set */
> @@ -70,6 +71,7 @@
>  struct fme_mgr_priv {
>  	void __iomem *ioaddr;
>  	u64 pr_error;
> +	struct dfl_compat_id compat_id;
>  };
> 
>  static u64 pr_error_to_mgr_status(u64 err)
> @@ -272,13 +274,21 @@ 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 void _fme_mgr_get_compat_id(void __iomem *fme_pr,
> +				   struct dfl_compat_id *id)
>  {
>  	id->id_l = readq(fme_pr + FME_PR_INTFC_ID_L);
>  	id->id_h = readq(fme_pr + FME_PR_INTFC_ID_H);
>  }
> 
> +void fme_mgr_get_compat_id(struct fpga_manager *mgr,
> +			   struct dfl_compat_id *id)
> +{
> +	struct fme_mgr_priv *priv = mgr->priv;
> +	*id = priv->compat_id;
> +}
> +EXPORT_SYMBOL_GPL(fme_mgr_get_compat_id);
> +
>  static int fme_mgr_probe(struct platform_device *pdev)
>  {
>  	struct dfl_fme_mgr_pdata *pdata = dev_get_platdata(&pdev->dev);
> @@ -306,7 +316,7 @@ static int fme_mgr_probe(struct platform_device *pdev)
>  	if (!compat_id)
>  		return -ENOMEM;
> 
> -	fme_mgr_get_compat_id(priv->ioaddr, compat_id);
> +	_fme_mgr_get_compat_id(priv->ioaddr, &priv->compat_id);
> 
>  	mgr = devm_fpga_mgr_create(dev, "DFL FME FPGA Manager",
>  				   &fme_mgr_ops, priv);
> diff --git a/drivers/fpga/dfl-fme-region.c b/drivers/fpga/dfl-fme-region.c
> index ca7277d3d30a9..d21eacbf2469f 100644
> --- a/drivers/fpga/dfl-fme-region.c
> +++ b/drivers/fpga/dfl-fme-region.c
> @@ -17,6 +17,7 @@
>  #include <linux/fpga/fpga-mgr.h>
>  #include <linux/fpga/fpga-region.h>
> 
> +#include "dfl.h"
>  #include "dfl-fme-pr.h"
> 
>  static int fme_region_get_bridges(struct fpga_region *region)
> @@ -27,8 +28,21 @@ static int fme_region_get_bridges(struct fpga_region
> *region)
>  	return fpga_bridge_get_to_list(dev, region->info, &region->bridge_list);
>  }
> 
> +static ssize_t fme_region_compat_id_show(struct fpga_region *region, char
> *buf)
> +{
> +	struct fpga_manager *mgr = region->mgr;
> +	struct dfl_compat_id compat_id;
> +
> +	fme_mgr_get_compat_id(mgr, &compat_id);

It's better to have a common interface, otherwise this region driver depends on
one specific mgr driver FPGA_DFL_FME_MGR. Ideally this region driver can be
reused with a new fpga mgr driver.

Compat id can be per-region or shared one from fpga-mgr. In this hardware, all
regions share the same compat_id from fpga-mgr.

I think reuse fpga-mgr compatibility id can be done via fpga-mgr data structure
or some common API exposed by fpga-mgr. In the first implementation, we
added it to fpga-mgr data structure which has less code.

Thanks
Hao

> +
> +	return sysfs_emit(buf, "%016llx%016llx\n",
> +			  (unsigned long long)compat_id.id_h,
> +			  (unsigned long long)compat_id.id_l);
> +}
> +
>  static const struct fpga_region_ops fme_fpga_region_ops = {
>  	.get_bridges = fme_region_get_bridges,
> +	.compat_id_show = fme_region_compat_id_show,
>  };
> 
>  static int fme_region_probe(struct platform_device *pdev)
> diff --git a/drivers/fpga/dfl.h b/drivers/fpga/dfl.h
> index 2b82c96ba56c7..a83fd11b390fc 100644
> --- a/drivers/fpga/dfl.h
> +++ b/drivers/fpga/dfl.h
> @@ -169,6 +169,20 @@
>  #define PORT_UINT_CAP_INT_NUM	GENMASK_ULL(11, 0)	/* Interrupts
> num */
>  #define PORT_UINT_CAP_FST_VECT	GENMASK_ULL(23, 12)	/* First Vector
> */
> 
> +/**
> + * struct dfl_compat_id - id for compatibility check
> + *
> + * @id_h: high 64bit of the compat_id
> + * @id_l: low 64bit of the compat_id
> + */
> +struct dfl_compat_id {
> +	u64 id_h;
> +	u64 id_l;
> +};
> +
> +void fme_mgr_get_compat_id(struct fpga_manager *mgr,
> +			   struct dfl_compat_id *id);
> +
>  /**
>   * struct dfl_fpga_port_ops - port ops
>   *
> --
> 2.26.3