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Date:   Wed, 14 Feb 2018 13:03:19 -0800
From:   Moritz Fischer <mdf@kernel.org>
To:     Wu Hao <hao.wu@intel.com>
Cc:     atull@kernel.org, mdf@kernel.org, linux-fpga@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
        luwei.kang@intel.com, yi.z.zhang@intel.com,
        Xiao Guangrong <guangrong.xiao@linux.intel.com>,
        Tim Whisonant <tim.whisonant@intel.com>,
        Enno Luebbers <enno.luebbers@intel.com>,
        Shiva Rao <shiva.rao@intel.com>,
        Christopher Rauer <christopher.rauer@intel.com>
Subject: Re: [PATCH v4 07/24] fpga: dfl: add feature device infrastructure
Message-ID: <20180214210319.GC25618@tyrael.ni.corp.natinst.com>
References: <1518513893-4719-1-git-send-email-hao.wu@intel.com>
 <1518513893-4719-8-git-send-email-hao.wu@intel.com>
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HI Hao,

On Tue, Feb 13, 2018 at 05:24:36PM +0800, Wu Hao wrote:
> From: Xiao Guangrong <guangrong.xiao@linux.intel.com>
>=20
> This patch abstracts the common operations of the sub features, and defin=
es
> the feature_ops data structure, including init, uinit and ioctl function
> pointers. And this patch adds some common helper functions for FME and AFU
> drivers, e.g feature_dev_use_begin/end which are used to ensure exclusive
> usage of the feature device file.
>=20
> Signed-off-by: Tim Whisonant <tim.whisonant@intel.com>
> Signed-off-by: Enno Luebbers <enno.luebbers@intel.com>
> Signed-off-by: Shiva Rao <shiva.rao@intel.com>
> Signed-off-by: Christopher Rauer <christopher.rauer@intel.com>
> Signed-off-by: Kang Luwei <luwei.kang@intel.com>
> Signed-off-by: Zhang Yi <yi.z.zhang@intel.com>
> Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
> Signed-off-by: Wu Hao <hao.wu@intel.com>
> ---
> v2: rebased
> v3: use const for feature_ops.
>     replace pci related function.
> v4: rebase and add more comments in code.
> ---
>  drivers/fpga/dfl.c | 59 +++++++++++++++++++++++++++++++++++++
>  drivers/fpga/dfl.h | 85 ++++++++++++++++++++++++++++++++++++++++++++++++=
+++++-
>  2 files changed, 143 insertions(+), 1 deletion(-)
>=20
> diff --git a/drivers/fpga/dfl.c b/drivers/fpga/dfl.c
> index 38dc819..c0aad87 100644
> --- a/drivers/fpga/dfl.c
> +++ b/drivers/fpga/dfl.c
> @@ -74,6 +74,65 @@ static enum fpga_id_type feature_dev_id_type(struct pl=
atform_device *pdev)
>  	return FPGA_ID_MAX;
>  }
> =20
> +void fpga_dev_feature_uinit(struct platform_device *pdev)
> +{
> +	struct feature *feature;
> +	struct feature_platform_data *pdata =3D dev_get_platdata(&pdev->dev);
See comment below w.r.t ordering declarations. Not a must for sure.
> +
> +	fpga_dev_for_each_feature(pdata, feature)
> +		if (feature->ops) {
> +			feature->ops->uinit(pdev, feature);
> +			feature->ops =3D NULL;
> +		}
> +}
> +EXPORT_SYMBOL_GPL(fpga_dev_feature_uinit);
> +
> +static int
> +feature_instance_init(struct platform_device *pdev,
> +		      struct feature_platform_data *pdata,
> +		      struct feature *feature, struct feature_driver *drv)
> +{
> +	int ret;
> +
> +	WARN_ON(!feature->ioaddr);

Not sure I understand correctly, is the !feature->ioaddr a use-case that
happens? If not just return early.
> +
> +	ret =3D drv->ops->init(pdev, feature);
> +	if (ret)
> +		return ret;
> +
> +	feature->ops =3D drv->ops;
> +
> +	return ret;
> +}
> +
> +int fpga_dev_feature_init(struct platform_device *pdev,
> +			  struct feature_driver *feature_drvs)
> +{
> +	struct feature *feature;
> +	struct feature_driver *drv =3D feature_drvs;
> +	struct feature_platform_data *pdata =3D dev_get_platdata(&pdev->dev);
> +	int ret;
We don't have clear guidelines here, but some subsystems want reverse
X-Mas tree declarations.
> +
> +	while (drv->ops) {
> +		fpga_dev_for_each_feature(pdata, feature) {
> +			/* match feature and drv using id */
> +			if (feature->id =3D=3D drv->id) {
> +				ret =3D feature_instance_init(pdev, pdata,
> +							    feature, drv);
> +				if (ret)
> +					goto exit;
> +			}
> +		}
> +		drv++;
> +	}
> +
> +	return 0;
> +exit:
> +	fpga_dev_feature_uinit(pdev);
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(fpga_dev_feature_init);
> +
>  struct fpga_chardev_info {
>  	const char *name;
>  	dev_t devt;
> diff --git a/drivers/fpga/dfl.h b/drivers/fpga/dfl.h
> index d6ecda1..ede1e95 100644
> --- a/drivers/fpga/dfl.h
> +++ b/drivers/fpga/dfl.h
> @@ -132,6 +132,17 @@
>  #define PORT_CTRL_SFTRST_ACK	BIT(4)			/* HW ack for reset */
> =20
>  /**
> + * struct feature_driver - sub feature's driver
> + *
> + * @id:	sub feature id.
> + * @ops: ops of this sub feature.
> + */
> +struct feature_driver {
> +	u64 id;
> +	const struct feature_ops *ops;
> +};
> +
> +/**
>   * struct feature - sub feature of the feature devices
>   *
>   * @id:	sub feature id.
> @@ -139,13 +150,17 @@
>   *		    this index is used to find its mmio resource from the
>   *		    feature dev (platform device)'s reources.
>   * @ioaddr: mapped mmio resource address.
> + * @ops: ops of this sub feature.
>   */
>  struct feature {
>  	u64 id;
>  	int resource_index;
>  	void __iomem *ioaddr;
> +	const struct feature_ops *ops;
>  };
> =20
> +#define DEV_STATUS_IN_USE	0
> +
>  /**
>   * struct feature_platform_data - platform data for feature devices
>   *
> @@ -155,6 +170,8 @@ struct feature {
>   * @dev: ptr to platform device linked with this platform data.
>   * @disable_count: count for port disable.
>   * @num: number for sub features.
> + * @dev_status: dev status (e.g DEV_STATUS_IN_USE).
> + * @private: ptr to feature dev private data.
>   * @features: sub features of this feature dev.
>   */
>  struct feature_platform_data {
> @@ -163,11 +180,44 @@ struct feature_platform_data {
>  	struct cdev cdev;
>  	struct platform_device *dev;
>  	unsigned int disable_count;
> -
> +	unsigned long dev_status;
> +	void *private;
>  	int num;
>  	struct feature features[0];
>  };
> =20
> +static inline int feature_dev_use_begin(struct feature_platform_data *pd=
ata)
> +{
> +	/* Test and set IN_USE flags to ensure file is exclusively used */
> +	if (test_and_set_bit_lock(DEV_STATUS_IN_USE, &pdata->dev_status))
> +		return -EBUSY;
> +
> +	return 0;
> +}
> +
> +static inline void feature_dev_use_end(struct feature_platform_data *pda=
ta)
> +{
> +	clear_bit_unlock(DEV_STATUS_IN_USE, &pdata->dev_status);
> +}
> +
> +static inline void
> +fpga_pdata_set_private(struct feature_platform_data *pdata, void *privat=
e)
> +{
> +	pdata->private =3D private;
> +}
> +
> +static inline void *fpga_pdata_get_private(struct feature_platform_data =
*pdata)
> +{
> +	return pdata->private;
> +}
> +
> +struct feature_ops {
> +	int (*init)(struct platform_device *pdev, struct feature *feature);
> +	void (*uinit)(struct platform_device *pdev, struct feature *feature);
> +	long (*ioctl)(struct platform_device *pdev, struct feature *feature,
> +		      unsigned int cmd, unsigned long arg);
> +};
> +
>  #define FPGA_FEATURE_DEV_FME		"dfl-fme"
>  #define FPGA_FEATURE_DEV_PORT		"dfl-port"
> =20
> @@ -177,6 +227,10 @@ static inline int feature_platform_data_size(const i=
nt num)
>  		num * sizeof(struct feature);
>  }
> =20
> +void fpga_dev_feature_uinit(struct platform_device *pdev);
> +int fpga_dev_feature_init(struct platform_device *pdev,
> +			  struct feature_driver *feature_drvs);
> +
>  enum fpga_devt_type {
>  	FPGA_DEVT_FME,
>  	FPGA_DEVT_PORT,
> @@ -257,6 +311,15 @@ static inline int fpga_port_reset(struct platform_de=
vice *pdev)
>  	return ret;
>  }
> =20
> +static inline
> +struct platform_device *fpga_inode_to_feature_dev(struct inode *inode)
> +{
> +	struct feature_platform_data *pdata;
> +
> +	pdata =3D container_of(inode->i_cdev, struct feature_platform_data, cde=
v);
> +	return pdata->dev;
> +}
> +
>  #define fpga_dev_for_each_feature(pdata, feature)			    \
>  	for ((feature) =3D (pdata)->features;				    \
>  	   (feature) < (pdata)->features + (pdata)->num; (feature)++)
> @@ -284,6 +347,17 @@ static inline void __iomem *get_feature_ioaddr_by_id=
(struct device *dev, u64 id)
>  	return NULL;
>  }
> =20
> +static inline bool is_feature_present(struct device *dev, u64 id)
> +{
> +	return !!get_feature_ioaddr_by_id(dev, id);
> +}
> +
> +static inline struct device *
> +fpga_pdata_to_parent(struct feature_platform_data *pdata)
> +{
> +	return pdata->dev->dev.parent->parent;
> +}
> +
>  static inline bool feature_is_fme(void __iomem *base)
>  {
>  	u64 v =3D readq(base + DFH);
> @@ -376,4 +450,13 @@ fpga_cdev_find_port(struct fpga_cdev *cdev, void *da=
ta,
> =20
>  	return pdev;
>  }
> +
> +static inline struct fpga_cdev *
> +fpga_pdata_to_fpga_cdev(struct feature_platform_data *pdata)
> +{
> +	struct device *dev =3D pdata->dev->dev.parent;
> +	struct fpga_region *region =3D to_fpga_region(dev);
> +
> +	return container_of(region, struct fpga_cdev, region);
> +}
>  #endif /* __FPGA_DFL_H */
> --=20
> 2.7.4
>=20

Thanks,
Moritz

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