netdev - RE: [RFC PATCH 2/6] fpga: dfl: export network configuration info for DFL based FPGA

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Date:   Mon, 26 Oct 2020 03:29:06 +0000
From:   "Wu, Hao" <hao.wu@...el.com>
To:     "Xu, Yilun" <yilun.xu@...el.com>,
        "Brandeburg, Jesse" <jesse.brandeburg@...el.com>,
        "Nguyen, Anthony L" <anthony.l.nguyen@...el.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "mdf@...nel.org" <mdf@...nel.org>,
        "lee.jones@...aro.org" <lee.jones@...aro.org>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-fpga@...r.kernel.org" <linux-fpga@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "trix@...hat.com" <trix@...hat.com>,
        "lgoncalv@...hat.com" <lgoncalv@...hat.com>
Subject: RE: [RFC PATCH 2/6] fpga: dfl: export network configuration info for
 DFL based FPGA

> Subject: [RFC PATCH 2/6] fpga: dfl: export network configuration info for DFL
> based FPGA
> 
> This patch makes preparation for supporting DFL Ether Group private
> feature driver, which reads bitstream_id.vendor_net_cfg field to
> determin the interconnection of network components on FPGA device.
> 
> Signed-off-by: Xu Yilun <yilun.xu@...el.com>
> ---
>  drivers/fpga/dfl-fme-main.c | 10 ++--------
>  drivers/fpga/dfl.c          | 21 +++++++++++++++++++++
>  drivers/fpga/dfl.h          | 12 ++++++++++++
>  include/linux/dfl.h         |  2 ++
>  4 files changed, 37 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/fpga/dfl-fme-main.c b/drivers/fpga/dfl-fme-main.c
> index 77ea04d..a2b8ba0 100644
> --- a/drivers/fpga/dfl-fme-main.c
> +++ b/drivers/fpga/dfl-fme-main.c
> @@ -46,14 +46,8 @@ static DEVICE_ATTR_RO(ports_num);
>  static ssize_t bitstream_id_show(struct device *dev,
>  				 struct device_attribute *attr, char *buf)
>  {
> -	void __iomem *base;
> -	u64 v;
> -
> -	base = dfl_get_feature_ioaddr_by_id(dev,
> FME_FEATURE_ID_HEADER);
> -
> -	v = readq(base + FME_HDR_BITSTREAM_ID);
> -
> -	return scnprintf(buf, PAGE_SIZE, "0x%llx\n", (unsigned long long)v);
> +	return scnprintf(buf, PAGE_SIZE, "0x%llx\n",
> +			 (unsigned long long)dfl_get_bitstream_id(dev));
>  }
>  static DEVICE_ATTR_RO(bitstream_id);
> 
> diff --git a/drivers/fpga/dfl.c b/drivers/fpga/dfl.c
> index bc35750..ca3c678 100644
> --- a/drivers/fpga/dfl.c
> +++ b/drivers/fpga/dfl.c
> @@ -537,6 +537,27 @@ void dfl_driver_unregister(struct dfl_driver *dfl_drv)
>  }
>  EXPORT_SYMBOL(dfl_driver_unregister);
> 
> +int dfl_dev_get_vendor_net_cfg(struct dfl_device *dfl_dev)
> +{
> +	struct device *fme_dev;
> +	u64 v;
> +
> +	if (!dfl_dev)
> +		return -EINVAL;
> +
> +	if (dfl_dev->type == FME_ID)
> +		fme_dev = dfl_dev->dev.parent;
> +	else
> +		fme_dev = dfl_dev->cdev->fme_dev;

All of them have cdev, is my understanding correct?
If so, why handle it differently here?

> +
> +	if (!fme_dev)
> +		return -EINVAL;

ENODEV?

> +
> +	v = dfl_get_bitstream_id(fme_dev);
> +	return (int)FIELD_GET(FME_BID_VENDOR_NET_CFG, v);
> +}
> +EXPORT_SYMBOL_GPL(dfl_dev_get_vendor_net_cfg);
> +
>  #define is_header_feature(feature) ((feature)->id ==
> FEATURE_ID_FIU_HEADER)
> 
>  /**
> diff --git a/drivers/fpga/dfl.h b/drivers/fpga/dfl.h
> index 2b82c96..6c7a6961 100644
> --- a/drivers/fpga/dfl.h
> +++ b/drivers/fpga/dfl.h
> @@ -104,6 +104,9 @@
>  #define FME_CAP_CACHE_SIZE	GENMASK_ULL(43, 32)	/* cache size
> in KB */
>  #define FME_CAP_CACHE_ASSOC	GENMASK_ULL(47, 44)	/*
> Associativity */
> 
> +/* FME BITSTREAM_ID Register Bitfield */

Bitstream ID, same style as others.

> +#define FME_BID_VENDOR_NET_CFG	GENMASK_ULL(35, 32)     /* vendor
> net cfg */
> +
>  /* FME Port Offset Register Bitfield */
>  /* Offset to port device feature header */
>  #define FME_PORT_OFST_DFH_OFST	GENMASK_ULL(23, 0)
> @@ -397,6 +400,15 @@ static inline bool is_dfl_feature_present(struct
> device *dev, u16 id)
>  	return !!dfl_get_feature_ioaddr_by_id(dev, id);
>  }
> 
> +static inline u64 dfl_get_bitstream_id(struct device *dev)
> +{
> +	void __iomem *base;
> +
> +	base = dfl_get_feature_ioaddr_by_id(dev,
> FME_FEATURE_ID_HEADER);
> +
> +	return readq(base + FME_HDR_BITSTREAM_ID);
> +}
> +
>  static inline
>  struct device *dfl_fpga_pdata_to_parent(struct dfl_feature_platform_data
> *pdata)
>  {
> diff --git a/include/linux/dfl.h b/include/linux/dfl.h
> index e1b2471..5ee2b1e 100644
> --- a/include/linux/dfl.h
> +++ b/include/linux/dfl.h
> @@ -67,6 +67,8 @@ struct dfl_driver {
>  #define to_dfl_dev(d) container_of(d, struct dfl_device, dev)
>  #define to_dfl_drv(d) container_of(d, struct dfl_driver, drv)
> 
> +int dfl_dev_get_vendor_net_cfg(struct dfl_device *dfl_dev);

It seems the vendor net configuration can be provided by a
vendor specific method. So bid_vendor_net_cfg maybe a better name?

Thanks
Hao

> +
>  /*
>   * use a macro to avoid include chaining to get THIS_MODULE.
>   */
> --
> 2.7.4