Date:   Tue, 10 Mar 2020 18:21:43 +0800
From:   Wu Hao <hao.wu@...el.com>
To:     Xu Yilun <yilun.xu@...el.com>
Cc:     mdf@...nel.org, linux-fpga@...r.kernel.org,
        linux-kernel@...r.kernel.org, Luwei Kang <luwei.kang@...el.com>
Subject: Re: [PATCH 1/7] fpga: dfl: parse interrupt info for feature devices
 on enumeration

On Tue, Mar 10, 2020 at 05:25:31PM +0800, Xu Yilun wrote:
> On Tue, Mar 10, 2020 at 10:26:49AM +0800, Wu Hao wrote:
> > Hi Yilun
> > 
> > Some comments inline.
> > 
> > On Mon, Mar 09, 2020 at 06:29:44PM +0800, Xu Yilun wrote:
> > > DFL based FPGA devices could support interrupts for different purposes,
> > > but current DFL framework only supports feature device enumeration with
> > > given MMIO resources information via common DFL headers. This patch
> > > introduces one new API dfl_fpga_enum_info_add_irq for low level bus
> > > drivers (e.g. PCIe device driver) to pass its interrupt resources
> > > information to DFL framework for enumeration, and also adds interrupt
> > > enumeration code in framework to parse and assign interrupt resources
> > > for enumerated feature devices and their own sub features.
> > > 
> > > With this patch, DFL framework enumerates interrupt resources for core
> > > features, including PORT Error Reporting, FME (FPGA Management Engine)
> > > Error Reporting and also AFU User Interrupts.
> > > 
> > > Signed-off-by: Luwei Kang <luwei.kang@...el.com>
> > > Signed-off-by: Wu Hao <hao.wu@...el.com>
> > > Signed-off-by: Xu Yilun <yilun.xu@...el.com>
> > > ---
> > >  drivers/fpga/dfl.c | 140 +++++++++++++++++++++++++++++++++++++++++++++++++++--
> > >  drivers/fpga/dfl.h |  40 +++++++++++++++
> > >  2 files changed, 176 insertions(+), 4 deletions(-)
> > > 
> > > diff --git a/drivers/fpga/dfl.c b/drivers/fpga/dfl.c
> > > index 9909948..493822d 100644
> > > --- a/drivers/fpga/dfl.c
> > > +++ b/drivers/fpga/dfl.c
> > > @@ -11,6 +11,7 @@
> > >   *   Xiao Guangrong <guangrong.xiao@...ux.intel.com>
> > >   */
> > >  #include <linux/module.h>
> > > +#include <asm/irq.h>
> > >  
> > >  #include "dfl.h"
> > >  
> > > @@ -421,6 +422,9 @@ EXPORT_SYMBOL_GPL(dfl_fpga_dev_ops_unregister);
> > >   *
> > >   * @dev: device to enumerate.
> > >   * @cdev: the container device for all feature devices.
> > > + * @nr_irqs: number of irqs for all feature devices.
> > > + * @irq_table: Linux IRQ numbers for all irqs, indexed by local irq index of
> > > + *	       this device.
> > >   * @feature_dev: current feature device.
> > >   * @ioaddr: header register region address of feature device in enumeration.
> > >   * @sub_features: a sub features linked list for feature device in enumeration.
> > > @@ -429,6 +433,9 @@ EXPORT_SYMBOL_GPL(dfl_fpga_dev_ops_unregister);
> > >  struct build_feature_devs_info {
> > >  	struct device *dev;
> > >  	struct dfl_fpga_cdev *cdev;
> > > +	unsigned int nr_irqs;
> > > +	int *irq_table;
> > > +
> > >  	struct platform_device *feature_dev;
> > >  	void __iomem *ioaddr;
> > >  	struct list_head sub_features;
> > > @@ -442,12 +449,16 @@ struct build_feature_devs_info {
> > >   * @mmio_res: mmio resource of this sub feature.
> > >   * @ioaddr: mapped base address of mmio resource.
> > >   * @node: node in sub_features linked list.
> > > + * @irq_base: start of irq index in this sub feature.
> > > + * @nr_irqs: number of irqs of this sub feature.
> > >   */
> > >  struct dfl_feature_info {
> > >  	u64 fid;
> > >  	struct resource mmio_res;
> > >  	void __iomem *ioaddr;
> > >  	struct list_head node;
> > > +	unsigned int irq_base;
> > > +	unsigned int nr_irqs;
> > >  };
> > >  
> > >  static void dfl_fpga_cdev_add_port_dev(struct dfl_fpga_cdev *cdev,
> > > @@ -520,6 +531,8 @@ static int build_info_commit_dev(struct build_feature_devs_info *binfo)
> > >  	/* fill features and resource information for feature dev */
> > >  	list_for_each_entry_safe(finfo, p, &binfo->sub_features, node) {
> > >  		struct dfl_feature *feature = &pdata->features[index];
> > > +		struct dfl_feature_irq_ctx *ctx;
> > > +		int i, virq;
> > >  
> > >  		/* save resource information for each feature */
> > >  		feature->id = finfo->fid;
> > > @@ -527,6 +540,24 @@ static int build_info_commit_dev(struct build_feature_devs_info *binfo)
> > >  		feature->ioaddr = finfo->ioaddr;
> > >  		fdev->resource[index++] = finfo->mmio_res;
> > >  
> > > +		if (finfo->nr_irqs) {
> > > +			ctx = devm_kcalloc(binfo->dev, finfo->nr_irqs,
> > > +					   sizeof(*ctx), GFP_KERNEL);
> > > +			if (!ctx)
> > > +				return -ENOMEM;
> > > +
> > > +			for (i = 0; i < finfo->nr_irqs; i++) {
> > > +				virq = binfo->irq_table[finfo->irq_base + i];
> > 
> > Looks like it checks the irq_table input in commit_dev which is the last step
> > of enumeration. I feel that maybe it's better to check the input earlier, e.g.
> > in dfl_fpga_enum_info_add_irq() function below.
> 
> Yes the check could be done earlier. But maybe too early checking in
> dfl_fpga_enum_info_add_irq(). I think dfl should allow holes in
> irq_table. We make sure sub features get valid irq numbers for
> each of its irq line, that should be enough.

Ok. Understand that it's possible that table may have holes. A multiple function
device may only want to hand part of its irq resources to DFL.

> 
> So maybe do this check in parse_feature_irqs() is better?

Yes. Sounds better.

> 
> > 
> > BTW: why it's named as virq? any specific meaning?
> 
> I'm just trying to indicate it's a linux irq number, not a hardware
> local irq number. I see the name also used as linux irq number in other
> drivers.
> 
> > 
> > > +				if (virq < 0 || virq > NR_IRQS)
> > > +					return -EINVAL;
> > > +
> > > +				ctx[i].irq = virq;
> > > +			}
> > > +
> > > +			feature->irq_ctx = ctx;
> > > +			feature->nr_irqs = finfo->nr_irqs;
> > > +		}
> > > +
> > >  		list_del(&finfo->node);
> > >  		kfree(finfo);
> > >  	}
> > > @@ -648,7 +679,8 @@ static u64 feature_id(void __iomem *start)
> > >  static int
> > >  create_feature_instance(struct build_feature_devs_info *binfo,
> > >  			struct dfl_fpga_enum_dfl *dfl, resource_size_t ofst,
> > > -			resource_size_t size, u64 fid)
> > > +			resource_size_t size, u64 fid, unsigned int irq_base,
> > > +			unsigned int nr_irqs)
> > >  {
> > >  	struct dfl_feature_info *finfo;
> > >  
> > > @@ -667,6 +699,8 @@ create_feature_instance(struct build_feature_devs_info *binfo,
> > >  	finfo->mmio_res.start = dfl->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;
> > >  	finfo->ioaddr = dfl->ioaddr + ofst;
> > >  
> > >  	list_add_tail(&finfo->node, &binfo->sub_features);
> > > @@ -684,7 +718,8 @@ static int parse_feature_port_afu(struct build_feature_devs_info *binfo,
> > >  
> > >  	WARN_ON(!size);
> > >  
> > > -	return create_feature_instance(binfo, dfl, ofst, size, FEATURE_ID_AFU);
> > > +	return create_feature_instance(binfo, dfl, ofst, size, FEATURE_ID_AFU,
> > > +				       0, 0);
> > >  }
> > >  
> > >  static int parse_feature_afu(struct build_feature_devs_info *binfo,
> > > @@ -724,7 +759,7 @@ static int parse_feature_fiu(struct build_feature_devs_info *binfo,
> > >  	if (ret)
> > >  		return ret;
> > >  
> > > -	ret = create_feature_instance(binfo, dfl, ofst, 0, 0);
> > > +	ret = create_feature_instance(binfo, dfl, ofst, 0, 0, 0, 0);
> > >  	if (ret)
> > >  		return ret;
> > >  	/*
> > > @@ -742,17 +777,72 @@ static int parse_feature_fiu(struct build_feature_devs_info *binfo,
> > >  	return ret;
> > >  }
> > >  
> > > +static void parse_feature_irqs(struct build_feature_devs_info *binfo,
> > > +			       struct dfl_fpga_enum_dfl *dfl,
> > > +			       resource_size_t ofst,
> > > +			       unsigned int *irq_base, unsigned int *nr_irqs)
> > > +{
> > > +	u64 id, v;
> > > +
> > > +	/*
> > > +	 * Ideally DFL framework should only read info from DFL header, but
> > > +	 * current version DFL only provides mmio resources information for
> > > +	 * each feature in DFL Header, no field for interrupt resources.
> > > +	 * Some interrupt resources information are provided by specific
> > > +	 * mmio registers of each components(e.g. different private features)
> > > +	 * which supports interrupt. So in order to parse and assign irq
> > > +	 * resources to different components, DFL framework has to look into
> > > +	 * specific capability registers of these core private features.
> > > +	 *
> > > +	 * Once future DFL version supports generic interrupt resources
> > > +	 * information in common DFL headers, below code could be replaced by
> > > +	 * some generic interrupt parsing code.
> > 
> > Per my understanding, even later version hardware uses common DFL Header Field
> > for interrupt resources enumeration, but we still keep this quirk for old
> > version hardware, right?
> 
> Yes, later version hardware will introduce the common DFL description of
> interrupt, which should override these quirks. But to be compatible to
> old version hardware, driver should fallback to these quirks for these 3
> sub feature if common interrupt description is not provided.

So please update above comments, below code is still needed later, and
won't be replaced. Thanks!

Hao

> 
> > 
> > > +	 */
> > > +
> > > +	id = feature_id((dfl->ioaddr + ofst));
> > > +
> > > +	if (id == PORT_FEATURE_ID_UINT) {
> > > +		v = readq(dfl->ioaddr + ofst + PORT_UINT_CAP);
> > > +		*irq_base = FIELD_GET(PORT_UINT_CAP_FST_VECT, v);
> > > +		*nr_irqs = FIELD_GET(PORT_UINT_CAP_INT_NUM, v);
> > > +	} else if (id == PORT_FEATURE_ID_ERROR) {
> > > +		v = readq(dfl->ioaddr + ofst + PORT_ERROR_CAP);
> > > +		*irq_base = FIELD_GET(PORT_ERROR_CAP_INT_VECT, v);
> > > +		*nr_irqs = FIELD_GET(PORT_ERROR_CAP_SUPP_INT, v);
> > > +	} else if (id == FME_FEATURE_ID_GLOBAL_ERR) {
> > > +		v = readq(dfl->ioaddr + ofst + FME_ERROR_CAP);
> > > +		*irq_base = FIELD_GET(FME_ERROR_CAP_INT_VECT, v);
> > > +		*nr_irqs = FIELD_GET(FME_ERROR_CAP_SUPP_INT, v);
> > > +	} else {
> > > +		return;
> > > +	}
> > > +
> > > +	dev_dbg(binfo->dev, "feature: 0x%llx, nr_irqs: %u, irq_base: %u\n",
> > > +		(unsigned long long)id, *nr_irqs, *irq_base);
> > > +
> > > +	if (*irq_base + *nr_irqs > binfo->nr_irqs) {
> > > +		*irq_base = 0;
> > > +		*nr_irqs = 0;
> > > +		dev_err(binfo->dev, "Inconsistent interrupt number on HW\n");
> > 
> > Maybe you want to print feature id as well in this error case.
> 
> OK. Print feature_id should be helpful when we hit the error.
> 
> > 
> > > +	}
> > > +}
> > > +
> > >  static int parse_feature_private(struct build_feature_devs_info *binfo,
> > >  				 struct dfl_fpga_enum_dfl *dfl,
> > >  				 resource_size_t ofst)
> > >  {
> > > +	unsigned int irq_base = 0, nr_irqs = 0;
> > > +
> > >  	if (!binfo->feature_dev) {
> > >  		dev_err(binfo->dev, "the private feature %llx does not belong to any AFU.\n",
> > >  			(unsigned long long)feature_id(dfl->ioaddr + ofst));
> > >  		return -EINVAL;
> > >  	}
> > >  
> > > -	return create_feature_instance(binfo, dfl, ofst, 0, 0);
> > > +	parse_feature_irqs(binfo, dfl, ofst, &irq_base, &nr_irqs);
> > > +
> > > +	return create_feature_instance(binfo, dfl, ofst, 0, 0, irq_base,
> > > +				       nr_irqs);
> > >  }
> > >  
> > >  /**
> > > @@ -853,6 +943,10 @@ void dfl_fpga_enum_info_free(struct dfl_fpga_enum_info *info)
> > >  		devm_kfree(dev, dfl);
> > >  	}
> > >  
> > > +	/* remove irq table */
> > > +	if (info->irq_table)
> > > +		devm_kfree(dev, info->irq_table);
> > > +
> > >  	devm_kfree(dev, info);
> > >  	put_device(dev);
> > >  }
> > > @@ -892,6 +986,40 @@ int dfl_fpga_enum_info_add_dfl(struct dfl_fpga_enum_info *info,
> > >  }
> > >  EXPORT_SYMBOL_GPL(dfl_fpga_enum_info_add_dfl);
> > >  
> > > +/**
> > > + * dfl_fpga_enum_info_add_irq - add irq table to enum info
> > > + *
> > > + * @info: ptr to dfl_fpga_enum_info
> > > + * @nr_irqs: number of irqs for all feature devices.
> > 
> > It's better to say, number of irqs of the dfl fpga device to be enumerated.
> > This function needs to be used before enumerate API.
> 
> Yes, I'll change it.
> 
> > 
> > > + * @irq_table: Linux IRQ numbers for all irqs, indexed by local irq index of
> > > + *	       this device.
> > > + *
> > > + * One FPGA device may have several interrupts. This function adds irq
> > > + * information of all feature devices to enumeration info for next step
> > 
> > Same here.
> 
> Yes.
> 
> > 
> > > + * enumeration.
> > > + *
> > > + * Return: 0 on success, negative error code otherwise.
> > > + */
> > > +int dfl_fpga_enum_info_add_irq(struct dfl_fpga_enum_info *info,
> > > +			       unsigned int nr_irqs, int *irq_table)
> > > +{
> > > +	if (!nr_irqs)
> > > +		return -EINVAL;
> > > +
> > 
> > Looks like currently it only allows add irq table once, so please document
> > this as it doesn't support users adding multiple irq tables.
> 
> Sure.
> 
> > 
> > Thanks
> > Hao
> > 
> > > +	if (info->irq_table)
> > > +		return -EEXIST;
> > > +
> > > +	info->irq_table = devm_kmemdup(info->dev, irq_table,
> > > +				       sizeof(int) * nr_irqs, GFP_KERNEL);
> > > +	if (!info->irq_table)
> > > +		return -ENOMEM;
> > > +
> > > +	info->nr_irqs = nr_irqs;
> > > +
> > > +	return 0;
> > > +}
> > > +EXPORT_SYMBOL_GPL(dfl_fpga_enum_info_add_irq);
> > > +
> > >  static int remove_feature_dev(struct device *dev, void *data)
> > >  {
> > >  	struct platform_device *pdev = to_platform_device(dev);
> > > @@ -959,6 +1087,10 @@ dfl_fpga_feature_devs_enumerate(struct dfl_fpga_enum_info *info)
> > >  	binfo->dev = info->dev;
> > >  	binfo->cdev = cdev;
> > >  
> > > +	binfo->nr_irqs = info->nr_irqs;
> > > +	if (info->nr_irqs)
> > > +		binfo->irq_table = info->irq_table;
> > > +
> > >  	/*
> > >  	 * start enumeration for all feature devices based on Device Feature
> > >  	 * Lists.
> > > diff --git a/drivers/fpga/dfl.h b/drivers/fpga/dfl.h
> > > index 4a9a33c..6a498cd 100644
> > > --- a/drivers/fpga/dfl.h
> > > +++ b/drivers/fpga/dfl.h
> > > @@ -112,6 +112,13 @@
> > >  #define FME_PORT_OFST_ACC_VF	1
> > >  #define FME_PORT_OFST_IMP	BIT_ULL(60)
> > >  
> > > +/* FME Error Capability Register */
> > > +#define FME_ERROR_CAP		0x70
> > > +
> > > +/* FME Error Capability Register Bitfield */
> > > +#define FME_ERROR_CAP_SUPP_INT	BIT_ULL(0)		/* Interrupt Support */
> > > +#define FME_ERROR_CAP_INT_VECT	GENMASK_ULL(12, 1)	/* Interrupt vector */
> > > +
> > >  /* PORT Header Register Set */
> > >  #define PORT_HDR_DFH		DFH
> > >  #define PORT_HDR_GUID_L		GUID_L
> > > @@ -145,6 +152,20 @@
> > >  #define PORT_STS_PWR_STATE_AP2	2			/* 90% throttling */
> > >  #define PORT_STS_PWR_STATE_AP6	6			/* 100% throttling */
> > >  
> > > +/* Port Error Capability Register */
> > > +#define PORT_ERROR_CAP		0x38
> > > +
> > > +/* Port Error Capability Register Bitfield */
> > > +#define PORT_ERROR_CAP_SUPP_INT	BIT_ULL(0)		/* Interrupt Support */
> > > +#define PORT_ERROR_CAP_INT_VECT	GENMASK_ULL(12, 1)	/* Interrupt vector */
> > > +
> > > +/* Port Uint Capability Register */
> > > +#define PORT_UINT_CAP		0x8
> > > +
> > > +/* Port Uint Capability Register Bitfield */
> > > +#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_fpga_port_ops - port ops
> > >   *
> > > @@ -189,6 +210,15 @@ struct dfl_feature_driver {
> > >  };
> > >  
> > >  /**
> > > + * struct dfl_feature_irq_ctx - dfl private feature interrupt context
> > > + *
> > > + * @irq: Linux IRQ number of this interrupt.
> > > + */
> > > +struct dfl_feature_irq_ctx {
> > > +	int irq;
> > > +};
> > > +
> > > +/**
> > >   * struct dfl_feature - sub feature of the feature devices
> > >   *
> > >   * @id: sub feature id.
> > > @@ -196,12 +226,16 @@ struct dfl_feature_driver {
> > >   *		    this index is used to find its mmio resource from the
> > >   *		    feature dev (platform device)'s reources.
> > >   * @ioaddr: mapped mmio resource address.
> > > + * @irq_ctx: interrupt context list.
> > > + * @nr_irqs: number of interrupt contexts.
> > >   * @ops: ops of this sub feature.
> > >   */
> > >  struct dfl_feature {
> > >  	u64 id;
> > >  	int resource_index;
> > >  	void __iomem *ioaddr;
> > > +	struct dfl_feature_irq_ctx *irq_ctx;
> > > +	unsigned int nr_irqs;
> > >  	const struct dfl_feature_ops *ops;
> > >  };
> > >  
> > > @@ -388,10 +422,14 @@ static inline u8 dfl_feature_revision(void __iomem *base)
> > >   *
> > >   * @dev: parent device.
> > >   * @dfls: list of device feature lists.
> > > + * @nr_irqs: number of irqs for all feature devices.
> > > + * @irq_table: Linux IRQ numbers for all irqs, indexed by hw irq numbers.
> > >   */
> > >  struct dfl_fpga_enum_info {
> > >  	struct device *dev;
> > >  	struct list_head dfls;
> > > +	unsigned int nr_irqs;
> > > +	int *irq_table;
> > >  };
> > >  
> > >  /**
> > > @@ -415,6 +453,8 @@ struct dfl_fpga_enum_info *dfl_fpga_enum_info_alloc(struct device *dev);
> > >  int dfl_fpga_enum_info_add_dfl(struct dfl_fpga_enum_info *info,
> > >  			       resource_size_t start, resource_size_t len,
> > >  			       void __iomem *ioaddr);
> > > +int dfl_fpga_enum_info_add_irq(struct dfl_fpga_enum_info *info,
> > > +			       unsigned int nr_irqs, int *irq_table);
> > >  void dfl_fpga_enum_info_free(struct dfl_fpga_enum_info *info);
> > >  
> > >  /**
> > > -- 
> > > 2.7.4

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