Date:   Thu, 6 Oct 2022 17:27:24 +0800
From:   Xu Yilun <yilun.xu@...el.com>
To:     matthew.gerlach@...ux.intel.com
Cc:     hao.wu@...el.com, russell.h.weight@...el.com,
        basheer.ahmed.muddebihal@...el.com, trix@...hat.com,
        mdf@...nel.org, linux-fpga@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        tianfei.zhang@...el.com, corbet@....net,
        gregkh@...uxfoundation.org, linux-serial@...r.kernel.org,
        jirislaby@...nel.org, geert+renesas@...der.be,
        andriy.shevchenko@...ux.intel.com,
        niklas.soderlund+renesas@...natech.se, macro@...am.me.uk,
        johan@...nel.org, lukas@...ner.de
Subject: Re: [PATCH v3 3/4] fpga: dfl: add basic support for DFHv1

On 2022-10-04 at 07:37:17 -0700, matthew.gerlach@...ux.intel.com wrote:
> From: Matthew Gerlach <matthew.gerlach@...ux.intel.com>
> 
> Add generic support for MSIX interrupts for DFL devices.
> 
> The location of a feature's registers is explicitly
> described in DFHv1 and can be relative to the base of the DFHv1
> or an absolute address.  Parse the location and pass the information
> to DFL driver.
> 
> Signed-off-by: Matthew Gerlach <matthew.gerlach@...ux.intel.com>
> ---
> v3: remove unneeded blank line
>     use clearer variable name
>     pass finfo into parse_feature_irqs()
>     refactor code for better indentation
>     use switch statement for irq parsing
>     squash in code parsing register location
> 
> v2: fix kernel doc
>     clarify use of DFH_VERSION field
> ---
>  drivers/fpga/dfl.c  | 150 ++++++++++++++++++++++++++++++++------------
>  drivers/fpga/dfl.h  |   3 +
>  include/linux/dfl.h |  20 ++++++
>  3 files changed, 134 insertions(+), 39 deletions(-)
> 
> diff --git a/drivers/fpga/dfl.c b/drivers/fpga/dfl.c
> index b9aae85ba930..6a74317e549e 100644
> --- a/drivers/fpga/dfl.c
> +++ b/drivers/fpga/dfl.c
> @@ -380,7 +380,11 @@ dfl_dev_add(struct dfl_feature_platform_data *pdata,
>  	ddev->type = feature_dev_id_type(pdev);
>  	ddev->feature_id = feature->id;
>  	ddev->revision = feature->revision;
> +	ddev->dfh_version = feature->dfh_version;
>  	ddev->cdev = pdata->dfl_cdev;
> +	ddev->csr_res.start = feature->csr_res.start;
> +	ddev->csr_res.end = feature->csr_res.end;
> +	ddev->csr_res.flags = IORESOURCE_MEM;
>  
>  	/* add mmio resource */
>  	parent_res = &pdev->resource[feature->resource_index];
> @@ -708,18 +712,24 @@ struct build_feature_devs_info {
>   * struct dfl_feature_info - sub feature info collected during feature dev build
>   *
>   * @fid: id of this sub feature.
> + * @revision: revision of this sub feature
> + * @dfh_version: version of Device Feature Header (DFH)
>   * @mmio_res: mmio resource of this sub feature.
>   * @ioaddr: mapped base address of mmio resource.
>   * @node: node in sub_features linked list.
> + * @csr_res: resource of DFHv1 feature registers
> + * @csr_size: DFHv1 size of feature registers
>   * @irq_base: start of irq index in this sub feature.
>   * @nr_irqs: number of irqs of this sub feature.
>   */
>  struct dfl_feature_info {
>  	u16 fid;
>  	u8 revision;
> +	u8 dfh_version;
>  	struct resource mmio_res;
>  	void __iomem *ioaddr;
>  	struct list_head node;
> +	struct resource csr_res;
>  	unsigned int irq_base;
>  	unsigned int nr_irqs;
>  };
> @@ -797,6 +807,9 @@ static int build_info_commit_dev(struct build_feature_devs_info *binfo)
>  		feature->dev = fdev;
>  		feature->id = finfo->fid;
>  		feature->revision = finfo->revision;
> +		feature->dfh_version = finfo->dfh_version;
> +		feature->csr_res.start = finfo->csr_res.start;
> +		feature->csr_res.end = finfo->csr_res.end;
>  
>  		/*
>  		 * the FIU header feature has some fundamental functions (sriov
> @@ -935,55 +948,74 @@ static u16 feature_id(u64 value)
>  }
>  
>  static int parse_feature_irqs(struct build_feature_devs_info *binfo,
> -			      resource_size_t ofst, u16 fid,
> -			      unsigned int *irq_base, unsigned int *nr_irqs)
> +			      resource_size_t ofst, struct dfl_feature_info *finfo)
>  {
>  	void __iomem *base = binfo->ioaddr + ofst;
>  	unsigned int i, ibase, inr = 0;
>  	enum dfl_id_type type;
> -	int virq;
> -	u64 v;
> -
> -	type = feature_dev_id_type(binfo->feature_dev);
> +	u16 fid = finfo->fid;
> +	u64 v, dfh_ver;
> +	int virq, off;
>  
>  	/*
>  	 * Ideally DFL framework should only read info from DFL header, but
> -	 * current version DFL only provides mmio resources information for
> +	 * current version, DFHv0, only provides mmio resources information for
>  	 * each feature in DFL Header, no field for interrupt resources.
>  	 * Interrupt resource information is provided by specific mmio
>  	 * registers of each private feature which supports interrupt. So in
>  	 * order to parse and assign irq resources, DFL framework has to look
>  	 * into specific capability registers of these private features.
>  	 *
> -	 * Once future DFL version supports generic interrupt resource
> -	 * information in common DFL headers, the generic interrupt parsing
> -	 * code will be added. But in order to be compatible to old version
> +	 * DFHv1 supports generic interrupt resource information in DFHv1
> +	 * parameter blocks. But in order to be compatible to old version
>  	 * DFL, the driver may still fall back to these quirks.
>  	 */
> -	if (type == PORT_ID) {
> -		switch (fid) {
> -		case PORT_FEATURE_ID_UINT:
> -			v = readq(base + PORT_UINT_CAP);
> -			ibase = FIELD_GET(PORT_UINT_CAP_FST_VECT, v);
> -			inr = FIELD_GET(PORT_UINT_CAP_INT_NUM, v);
> +
> +	switch (finfo->dfh_version) {
> +	case 0:
> +		type = feature_dev_id_type(binfo->feature_dev);
> +		if (type == PORT_ID) {
> +			switch (fid) {
> +			case PORT_FEATURE_ID_UINT:
> +				v = readq(base + PORT_UINT_CAP);
> +				ibase = FIELD_GET(PORT_UINT_CAP_FST_VECT, v);
> +				inr = FIELD_GET(PORT_UINT_CAP_INT_NUM, v);
> +				break;
> +			case PORT_FEATURE_ID_ERROR:
> +				v = readq(base + PORT_ERROR_CAP);
> +				ibase = FIELD_GET(PORT_ERROR_CAP_INT_VECT, v);
> +				inr = FIELD_GET(PORT_ERROR_CAP_SUPP_INT, v);
> +				break;
> +			}
> +		} else if (type == FME_ID) {
> +			if (fid == FME_FEATURE_ID_GLOBAL_ERR) {
> +				v = readq(base + FME_ERROR_CAP);
> +				ibase = FIELD_GET(FME_ERROR_CAP_INT_VECT, v);
> +				inr = FIELD_GET(FME_ERROR_CAP_SUPP_INT, v);
> +			}
> +		}
> +		break;
> +
> +	case 1:
> +		if (!dfhv1_has_params(base))
>  			break;
> -		case PORT_FEATURE_ID_ERROR:
> -			v = readq(base + PORT_ERROR_CAP);
> -			ibase = FIELD_GET(PORT_ERROR_CAP_INT_VECT, v);
> -			inr = FIELD_GET(PORT_ERROR_CAP_SUPP_INT, v);
> +
> +		off = dfhv1_find_param(base, ofst, DFHv1_PARAM_ID_MSIX);
> +		if (off < 0)
>  			break;
> -		}
> -	} else if (type == FME_ID) {
> -		if (fid == FME_FEATURE_ID_GLOBAL_ERR) {
> -			v = readq(base + FME_ERROR_CAP);
> -			ibase = FIELD_GET(FME_ERROR_CAP_INT_VECT, v);
> -			inr = FIELD_GET(FME_ERROR_CAP_SUPP_INT, v);
> -		}
> +
> +		ibase = readl(base + off + DFHv1_PARAM_MSIX_STARTV);
> +		inr = readl(base + off + DFHv1_PARAM_MSIX_NUMV);
> +		break;
> +
> +	default:
> +		dev_warn(binfo->dev, "unexpected DFH version %lld\n", dfh_ver);
> +		break;
>  	}
>  
>  	if (!inr) {
> -		*irq_base = 0;
> -		*nr_irqs = 0;
> +		finfo->irq_base = 0;
> +		finfo->nr_irqs = 0;
>  		return 0;
>  	}
>  
> @@ -1006,8 +1038,8 @@ static int parse_feature_irqs(struct build_feature_devs_info *binfo,
>  		}
>  	}
>  
> -	*irq_base = ibase;
> -	*nr_irqs = inr;
> +	finfo->irq_base = ibase;
> +	finfo->nr_irqs = inr;
>  
>  	return 0;
>  }
> @@ -1023,8 +1055,8 @@ static int
>  create_feature_instance(struct build_feature_devs_info *binfo,
>  			resource_size_t ofst, resource_size_t size, u16 fid)
>  {
> -	unsigned int irq_base, nr_irqs;
>  	struct dfl_feature_info *finfo;
> +	u8 dfh_version = 0;
>  	u8 revision = 0;
>  	int ret;
>  	u64 v;
> @@ -1032,7 +1064,7 @@ create_feature_instance(struct build_feature_devs_info *binfo,
>  	if (fid != FEATURE_ID_AFU) {
>  		v = readq(binfo->ioaddr + ofst);
>  		revision = FIELD_GET(DFH_REVISION, v);
> -
> +		dfh_version = FIELD_GET(DFH_VERSION, v);
>  		/* read feature size and id if inputs are invalid */
>  		size = size ? size : feature_size(v);
>  		fid = fid ? fid : feature_id(v);
> @@ -1041,21 +1073,33 @@ create_feature_instance(struct build_feature_devs_info *binfo,
>  	if (binfo->len - ofst < size)
>  		return -EINVAL;
>  
> -	ret = parse_feature_irqs(binfo, ofst, fid, &irq_base, &nr_irqs);
> -	if (ret)
> -		return ret;
> -
>  	finfo = kzalloc(sizeof(*finfo), GFP_KERNEL);
>  	if (!finfo)
>  		return -ENOMEM;
>  
>  	finfo->fid = fid;
>  	finfo->revision = revision;
> +	finfo->dfh_version = dfh_version;
>  	finfo->mmio_res.start = binfo->start + ofst;
>  	finfo->mmio_res.end = finfo->mmio_res.start + size - 1;
>  	finfo->mmio_res.flags = IORESOURCE_MEM;
> -	finfo->irq_base = irq_base;
> -	finfo->nr_irqs = nr_irqs;
> +
> +	ret = parse_feature_irqs(binfo, ofst, finfo);
> +	if (ret)
> +		return ret;
> +
> +	if (dfh_version == 1) {
> +		v = readq(binfo->ioaddr + ofst + DFHv1_CSR_ADDR);
> +		if (v & DFHv1_CSR_ADDR_REL)
> +			finfo->csr_res.start = FIELD_GET(DFHv1_CSR_ADDR_MASK, v);
> +		else
> +			finfo->csr_res.start = binfo->start + ofst
> +					       + FIELD_GET(DFHv1_CSR_ADDR_MASK, v);
> +
> +		v = readq(binfo->ioaddr + ofst + DFHv1_CSR_SIZE_GRP);
> +		finfo->csr_res.end = finfo->csr_res.start
> +				     + FIELD_GET(DFHv1_CSR_SIZE_GRP_SIZE, v) - 1;
> +	}
>  
>  	list_add_tail(&finfo->node, &binfo->sub_features);
>  	binfo->feature_num++;
> @@ -1879,6 +1923,34 @@ long dfl_feature_ioctl_set_irq(struct platform_device *pdev,
>  }
>  EXPORT_SYMBOL_GPL(dfl_feature_ioctl_set_irq);
>  
> +int dfhv1_find_param(void __iomem *base, resource_size_t max, int param)
> +{
> +	int off = DFHv1_PARAM_HDR;
> +	u64 v, next;
> +
> +	while (off < max) {
> +		v = readq(base + off);
> +		if (param == FIELD_GET(DFHv1_PARAM_HDR_ID, v))
> +			return (DFHv1_PARAM_DATA + off);
> +
> +		next = FIELD_GET(DFHv1_PARAM_HDR_NEXT_OFFSET, v);
> +		if (!next)
> +			break;
> +
> +		off += next;
> +	}
> +
> +	return -ENOENT;
> +}
> +EXPORT_SYMBOL_GPL(dfhv1_find_param);
> +
> +int dfhv1_has_params(void __iomem *dfh_base)
> +{
> +	return (FIELD_GET(DFHv1_CSR_SIZE_GRP_HAS_PARAMS,
> +		readq(dfh_base + DFHv1_CSR_SIZE_GRP)));
> +}
> +EXPORT_SYMBOL_GPL(dfhv1_has_params);
> +
>  static void __exit dfl_fpga_exit(void)
>  {
>  	dfl_chardev_uinit();
> diff --git a/drivers/fpga/dfl.h b/drivers/fpga/dfl.h
> index bd8720bc5320..0423aa8319ed 100644
> --- a/drivers/fpga/dfl.h
> +++ b/drivers/fpga/dfl.h
> @@ -266,6 +266,7 @@ struct dfl_feature_irq_ctx {
>   *		    this index is used to find its mmio resource from the
>   *		    feature dev (platform device)'s resources.
>   * @ioaddr: mapped mmio resource address.
> + * @csr_res: resource for DFHv1 feature registers
>   * @irq_ctx: interrupt context list.
>   * @nr_irqs: number of interrupt contexts.
>   * @ops: ops of this sub feature.
> @@ -276,8 +277,10 @@ struct dfl_feature {
>  	struct platform_device *dev;
>  	u16 id;
>  	u8 revision;
> +	u8 dfh_version;
>  	int resource_index;
>  	void __iomem *ioaddr;
> +	struct resource csr_res;
>  	struct dfl_feature_irq_ctx *irq_ctx;
>  	unsigned int nr_irqs;
>  	const struct dfl_feature_ops *ops;
> diff --git a/include/linux/dfl.h b/include/linux/dfl.h
> index 1a1a2b894687..71760c6a25d7 100644
> --- a/include/linux/dfl.h
> +++ b/include/linux/dfl.h
> @@ -39,6 +39,7 @@ enum dfl_id_type {
>   * @type: type of DFL FIU of the device. See enum dfl_id_type.
>   * @feature_id: feature identifier local to its DFL FIU type.
>   * @mmio_res: mmio resource of this dfl device.
> + * @csr_res: resource for DFHv1 feature registers

I think the combination of mmio_res & csr_res is confusing. Why a
special csr_res dedicated for DFHv1, and what the mmio_res stands for if
the csr_res exists? And they may overlap each other.

Could you present some general purpose mmio resource layout which is
compatible to dfl v0 & v1? People from other domains just need to know
the basic concept like how many register blocks in the device, what are
their ranges ...

Thanks,
Yilun

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