Re: [PATCH v9 1/3] fpga: mgr: Use standard dev_release for class driver

[Xu Yilun <yilun.xu@intel.com>]

On Tue, Jul 06, 2021 at 12:04:55PM -0700, Tom Rix wrote:
> Russ,
> 
> My two big concerns are.
> 
> compat_id does not belong in fpga_mgr_info, it belongs in fme_mgr_priv.
> 
> there are two register functions, there should be one.
> 
> 
> On 6/30/21 6:37 PM, Russ Weight wrote:
> > The FPGA manager class driver data structure is being treated as a
> > managed resource instead of using the standard dev_release call-back
> > function to release the class data structure. This change removes
> > the managed resource code for the freeing of the class data structure
> > and combines the create() and register() functions into a single
> > register() or register_simple() function.
> > 
> > The register() function accepts an info data structure to provide
> > flexibility in passing optional parameters. The register_simple()
> > function supports the current parameter list for users that don't
> > require the use of optional parameters.
> > 
> > The devm_fpga_mgr_register() function is retained, and the
> > devm_fpga_mgr_register_simple() function is added.
> > 
> > Signed-off-by: Russ Weight <russell.h.weight@intel.com>
> > Reviewed-by: Xu Yilun <yilun.xu@intel.com>
> > ---
> > v9:
> >    - Cleaned up documentation for the FPGA Manager register functions
> >    - Renamed fpga_mgr_register() to fpga_mgr_register_full()
> >    - Renamed fpga_mgr_register_simple() to fpga_mgr_register()
> >    - Renamed devm_fpga_mgr_register() to devm_fpga_mgr_register_full()
> >    - Renamed devm_fpga_mgr_register_simple() to devm_fpga_mgr_register()
> > v8:
> >    - Added reviewed-by tag.
> >    - Updated Documentation/driver-api/fpga/fpga-mgr.rst documentation.
> > v7:
> >    - Update the commit message to describe the new parameters for the
> >      *fpga_mgr_register() functions and to mention the
> >      *fpga_mgr_register_simple() functions.
> >    - Fix function prototypes in header file to rename dev to parent.
> >    - Make use of the PTR_ERR_OR_ZERO() macro when possible.
> >    - Some cleanup of comments.
> >    - Update function defintions/prototypes to apply const to the new info
> >      parameter.
> > v6:
> >    - Moved FPGA manager optional parameters out of the ops structure and
> >      back into the FPGA manager structure.
> >    - Changed fpga_mgr_register()/devm_fpga_mgr_register() parameters to
> >      accept an info data structure to provide flexibility in passing optional
> >      parameters.
> >    - Added fpga_mgr_register_simple()/devm_fpga_mgr_register_simple()
> >      functions to support current parameters for users that don't require
> >      the use of optional parameters.
> > v5:
> >    - Rebased on top of recently accepted patches.
> >    - Removed compat_id from the fpga_mgr_register() parameter list
> >      and added it to the fpga_manager_ops structure. This also required
> >      dynamically allocating the dfl-fme-ops structure in order to add
> >      the appropriate compat_id.
> > v4:
> >    - Added the compat_id parameter to fpga_mgr_register() and
> >      devm_fpga_mgr_register() to ensure that the compat_id is set before
> >      the device_register() call.
> > v3:
> >    - Cleaned up comment header for fpga_mgr_register()
> >    - Fix error return on ida_simple_get() failure
> > v2:
> >    - Restored devm_fpga_mgr_register() functionality, adapted for the combined
> >      create/register functionality.
> >    - All previous callers of devm_fpga_mgr_register() will continue to call
> >      devm_fpga_mgr_register().
> >    - replaced unnecessary ternary operators in return statements with standard
> >      if conditions.
> > ---
> >   Documentation/driver-api/fpga/fpga-mgr.rst |  34 +++-
> >   drivers/fpga/altera-cvp.c                  |  12 +-
> >   drivers/fpga/altera-pr-ip-core.c           |   7 +-
> >   drivers/fpga/altera-ps-spi.c               |   9 +-
> >   drivers/fpga/dfl-fme-mgr.c                 |  22 +--
> >   drivers/fpga/fpga-mgr.c                    | 215 +++++++++------------
> >   drivers/fpga/ice40-spi.c                   |   9 +-
> >   drivers/fpga/machxo2-spi.c                 |   9 +-
> >   drivers/fpga/socfpga-a10.c                 |  16 +-
> >   drivers/fpga/socfpga.c                     |   9 +-
> >   drivers/fpga/stratix10-soc.c               |  16 +-
> >   drivers/fpga/ts73xx-fpga.c                 |   9 +-
> >   drivers/fpga/xilinx-spi.c                  |  11 +-
> >   drivers/fpga/zynq-fpga.c                   |  16 +-
> >   drivers/fpga/zynqmp-fpga.c                 |   9 +-
> >   include/linux/fpga/fpga-mgr.h              |  62 ++++--
> >   16 files changed, 210 insertions(+), 255 deletions(-)
> > 
> > diff --git a/Documentation/driver-api/fpga/fpga-mgr.rst b/Documentation/driver-api/fpga/fpga-mgr.rst
> > index 4d926b452cb3..826ed8dc9210 100644
> > --- a/Documentation/driver-api/fpga/fpga-mgr.rst
> > +++ b/Documentation/driver-api/fpga/fpga-mgr.rst
> > @@ -24,7 +24,7 @@ How to support a new FPGA device
> >   --------------------------------
> >   To add another FPGA manager, write a driver that implements a set of ops.  The
> > -probe function calls fpga_mgr_register(), such as::
> > +probe function calls fpga_mgr_register() or fpga_mgr_register_full(), such as::
> >   	static const struct fpga_manager_ops socfpga_fpga_ops = {
> >   		.write_init = socfpga_fpga_ops_configure_init,
> > @@ -49,14 +49,14 @@ probe function calls fpga_mgr_register(), such as::
> >   		 * them in priv
> >   		 */
> > -		mgr = devm_fpga_mgr_create(dev, "Altera SOCFPGA FPGA Manager",
> > -					   &socfpga_fpga_ops, priv);
> > -		if (!mgr)
> > -			return -ENOMEM;
> > +		mgr = fpga_mgr_register(dev, "Altera SOCFPGA FPGA Manager",
> > +					&socfpga_fpga_ops, priv);
> > +		if (IS_ERR(mgr))
> > +			return PTR_ERR(mgr);
> >   		platform_set_drvdata(pdev, mgr);
> > -		return fpga_mgr_register(mgr);
> > +		return 0;
> >   	}
> >   	static int socfpga_fpga_remove(struct platform_device *pdev)
> > @@ -68,6 +68,11 @@ probe function calls fpga_mgr_register(), such as::
> >   		return 0;
> >   	}
> > +Alternatively, the probe function could call one of the resource managed
> > +register functions, devm_fpga_mgr_register() or devm_fpga_mgr_register_full().
> > +When these functions are used, the parameter syntax is the same, but the call
> > +to fpga_mgr_unregister() should be removed. In the above example, the
> > +socfpga_fpga_remove() function would not be required.
> >   The ops will implement whatever device specific register writes are needed to
> >   do the programming sequence for this particular FPGA.  These ops return 0 for
> > @@ -104,8 +109,13 @@ API for implementing a new FPGA Manager driver
> >   * ``fpga_mgr_states`` -  Values for :c:expr:`fpga_manager->state`.
> >   * struct fpga_manager -  the FPGA manager struct
> >   * struct fpga_manager_ops -  Low level FPGA manager driver ops
> > -* devm_fpga_mgr_create() -  Allocate and init a manager struct
> > -* fpga_mgr_register() -  Register an FPGA manager
> > +* fpga_mgr_register_full() -  Create and register an FPGA manager using the
> > +  fpga_mgr_info structure to provide the full flexibility of options
> > +* fpga_mgr_register() -  Create and register an FPGA manager using standard
> > +  arguments
> > +* devm_fpga_mgr_register_full() -  Resource managed version of
> > +  fpga_mgr_register_full()
> > +* devm_fpga_mgr_register() -  Resource managed version of fpga_mgr_register()
> >   * fpga_mgr_unregister() -  Unregister an FPGA manager
> >   .. kernel-doc:: include/linux/fpga/fpga-mgr.h
> > @@ -118,10 +128,16 @@ API for implementing a new FPGA Manager driver
> >      :functions: fpga_manager_ops
> >   .. kernel-doc:: drivers/fpga/fpga-mgr.c
> > -   :functions: devm_fpga_mgr_create
> > +   :functions: fpga_mgr_register_full
> >   .. kernel-doc:: drivers/fpga/fpga-mgr.c
> >      :functions: fpga_mgr_register
> > +.. kernel-doc:: drivers/fpga/fpga-mgr.c
> > +   :functions: devm_fpga_mgr_register_full
> > +
> > +.. kernel-doc:: drivers/fpga/fpga-mgr.c
> > +   :functions: devm_fpga_mgr_register
> > +
> >   .. kernel-doc:: drivers/fpga/fpga-mgr.c
> >      :functions: fpga_mgr_unregister
> > diff --git a/drivers/fpga/altera-cvp.c b/drivers/fpga/altera-cvp.c
> > index ccf4546eff29..4ffb9da537d8 100644
> > --- a/drivers/fpga/altera-cvp.c
> > +++ b/drivers/fpga/altera-cvp.c
> > @@ -652,19 +652,15 @@ static int altera_cvp_probe(struct pci_dev *pdev,
> >   	snprintf(conf->mgr_name, sizeof(conf->mgr_name), "%s @%s",
> >   		 ALTERA_CVP_MGR_NAME, pci_name(pdev));
> > -	mgr = devm_fpga_mgr_create(&pdev->dev, conf->mgr_name,
> > -				   &altera_cvp_ops, conf);
> > -	if (!mgr) {
> > -		ret = -ENOMEM;
> > +	mgr = fpga_mgr_register(&pdev->dev, conf->mgr_name,
> > +				&altera_cvp_ops, conf);
> > +	if (IS_ERR(mgr)) {
> > +		ret = PTR_ERR(mgr);
> >   		goto err_unmap;
> >   	}
> >   	pci_set_drvdata(pdev, mgr);
> > -	ret = fpga_mgr_register(mgr);
> > -	if (ret)
> > -		goto err_unmap;
> > -
> >   	return 0;
> >   err_unmap:
> > diff --git a/drivers/fpga/altera-pr-ip-core.c b/drivers/fpga/altera-pr-ip-core.c
> > index dfdf21ed34c4..be0667968d33 100644
> > --- a/drivers/fpga/altera-pr-ip-core.c
> > +++ b/drivers/fpga/altera-pr-ip-core.c
> > @@ -191,11 +191,8 @@ int alt_pr_register(struct device *dev, void __iomem *reg_base)
> >   		(val & ALT_PR_CSR_STATUS_MSK) >> ALT_PR_CSR_STATUS_SFT,
> >   		(int)(val & ALT_PR_CSR_PR_START));
> > -	mgr = devm_fpga_mgr_create(dev, dev_name(dev), &alt_pr_ops, priv);
> > -	if (!mgr)
> > -		return -ENOMEM;
> > -
> > -	return devm_fpga_mgr_register(dev, mgr);
> > +	mgr = devm_fpga_mgr_register(dev, dev_name(dev), &alt_pr_ops, priv);
> > +	return PTR_ERR_OR_ZERO(mgr);
> >   }
> >   EXPORT_SYMBOL_GPL(alt_pr_register);
> > diff --git a/drivers/fpga/altera-ps-spi.c b/drivers/fpga/altera-ps-spi.c
> > index 23bfd4d1ad0f..5e1e009dba89 100644
> > --- a/drivers/fpga/altera-ps-spi.c
> > +++ b/drivers/fpga/altera-ps-spi.c
> > @@ -302,12 +302,9 @@ static int altera_ps_probe(struct spi_device *spi)
> >   	snprintf(conf->mgr_name, sizeof(conf->mgr_name), "%s %s",
> >   		 dev_driver_string(&spi->dev), dev_name(&spi->dev));
> > -	mgr = devm_fpga_mgr_create(&spi->dev, conf->mgr_name,
> > -				   &altera_ps_ops, conf);
> > -	if (!mgr)
> > -		return -ENOMEM;
> > -
> > -	return devm_fpga_mgr_register(&spi->dev, mgr);
> > +	mgr = devm_fpga_mgr_register(&spi->dev, conf->mgr_name,
> > +				     &altera_ps_ops, conf);
> > +	return PTR_ERR_OR_ZERO(mgr);
> >   }
> >   static const struct spi_device_id altera_ps_spi_ids[] = {
> > diff --git a/drivers/fpga/dfl-fme-mgr.c b/drivers/fpga/dfl-fme-mgr.c
> > index d5861d13b306..620e7874ab53 100644
> > --- a/drivers/fpga/dfl-fme-mgr.c
> > +++ b/drivers/fpga/dfl-fme-mgr.c
> > @@ -282,7 +282,7 @@ static void fme_mgr_get_compat_id(void __iomem *fme_pr,
> >   static int fme_mgr_probe(struct platform_device *pdev)
> >   {
> >   	struct dfl_fme_mgr_pdata *pdata = dev_get_platdata(&pdev->dev);
> > -	struct fpga_compat_id *compat_id;
> > +	struct fpga_manager_info info = { 0 };
> >   	struct device *dev = &pdev->dev;
> >   	struct fme_mgr_priv *priv;
> >   	struct fpga_manager *mgr;
> > @@ -302,20 +302,16 @@ static int fme_mgr_probe(struct platform_device *pdev)
> >   			return PTR_ERR(priv->ioaddr);
> >   	}
> > -	compat_id = devm_kzalloc(dev, sizeof(*compat_id), GFP_KERNEL);
> > -	if (!compat_id)
> > +	info.name = "DFL FME FPGA Manager";
> > +	info.mops = &fme_mgr_ops;
> > +	info.priv = priv;
> > +	info.compat_id = devm_kzalloc(dev, sizeof(*info.compat_id), GFP_KERNEL);
> > +	if (!info.compat_id)
> >   		return -ENOMEM;
> could we limp along instead of failing ?
> > -	fme_mgr_get_compat_id(priv->ioaddr, compat_id);
> > -
> > -	mgr = devm_fpga_mgr_create(dev, "DFL FME FPGA Manager",
> > -				   &fme_mgr_ops, priv);
> > -	if (!mgr)
> > -		return -ENOMEM;
> > -
> > -	mgr->compat_id = compat_id;
> > -
> > -	return devm_fpga_mgr_register(dev, mgr);
> > +	fme_mgr_get_compat_id(priv->ioaddr, info.compat_id);
> > +	mgr = devm_fpga_mgr_register_full(dev, &info);
> > +	return PTR_ERR_OR_ZERO(mgr);
> >   }
> >   static struct platform_driver fme_mgr_driver = {
> > diff --git a/drivers/fpga/fpga-mgr.c b/drivers/fpga/fpga-mgr.c
> > index ecb4c3c795fa..5a913aa649fd 100644
> > --- a/drivers/fpga/fpga-mgr.c
> > +++ b/drivers/fpga/fpga-mgr.c
> > @@ -550,21 +550,19 @@ void fpga_mgr_unlock(struct fpga_manager *mgr)
> >   EXPORT_SYMBOL_GPL(fpga_mgr_unlock);
> >   /**
> > - * fpga_mgr_create - create and initialize an FPGA manager struct
> > + * fpga_mgr_register_full - create and register an FPGA Manager device
> >    * @parent:	fpga manager device from pdev
> > - * @name:	fpga manager name
> > - * @mops:	pointer to structure of fpga manager ops
> > - * @priv:	fpga manager private data
> > + * @info:	parameters for fpga manager
> >    *
> > - * The caller of this function is responsible for freeing the struct with
> > - * fpga_mgr_free().  Using devm_fpga_mgr_create() instead is recommended.
> > + * The caller of this function is responsible for calling fpga_mgr_unregister().
> > + * Using devm_fpga_mgr_register_full() instead is recommended.
> >    *
> > - * Return: pointer to struct fpga_manager or NULL
> > + * Return: pointer to struct fpga_manager pointer or ERR_PTR()
> >    */
> > -struct fpga_manager *fpga_mgr_create(struct device *parent, const char *name,
> > -				     const struct fpga_manager_ops *mops,
> > -				     void *priv)
> > +struct fpga_manager *
> > +fpga_mgr_register_full(struct device *parent, const struct fpga_manager_info *info)
> >   {
> > +	const struct fpga_manager_ops *mops = info->mops;
> >   	struct fpga_manager *mgr;
> >   	int id, ret;
> > @@ -572,29 +570,31 @@ struct fpga_manager *fpga_mgr_create(struct device *parent, const char *name,
> >   	    !mops->write_init || (!mops->write && !mops->write_sg) ||
> >   	    (mops->write && mops->write_sg)) {
> >   		dev_err(parent, "Attempt to register without fpga_manager_ops\n");
> > -		return NULL;
> > +		return ERR_PTR(-EINVAL);
> >   	}
> > -	if (!name || !strlen(name)) {
> > +	if (!info->name || !strlen(info->name)) {
> >   		dev_err(parent, "Attempt to register with no name!\n");
> > -		return NULL;
> > +		return ERR_PTR(-EINVAL);
> >   	}
> >   	mgr = kzalloc(sizeof(*mgr), GFP_KERNEL);
> >   	if (!mgr)
> > -		return NULL;
> > +		return ERR_PTR(-ENOMEM);
> >   	id = ida_simple_get(&fpga_mgr_ida, 0, 0, GFP_KERNEL);
> > -	if (id < 0)
> > +	if (id < 0) {
> > +		ret = id;
> >   		goto error_kfree;
> > +	}
> >   	mutex_init(&mgr->ref_mutex);
> > -	mgr->name = name;
> > -	mgr->mops = mops;
> > -	mgr->priv = priv;
> > +	mgr->name = info->name;
> > +	mgr->mops = info->mops;
> > +	mgr->priv = info->priv;
> > +	mgr->compat_id = info->compat_id;
> > -	device_initialize(&mgr->dev);
> >   	mgr->dev.class = fpga_mgr_class;
> >   	mgr->dev.groups = mops->groups;
> >   	mgr->dev.parent = parent;
> > @@ -605,6 +605,19 @@ struct fpga_manager *fpga_mgr_create(struct device *parent, const char *name,
> >   	if (ret)
> >   		goto error_device;
> > +	/*
> > +	 * Initialize framework state by requesting low level driver read state
> > +	 * from device.  FPGA may be in reset mode or may have been programmed
> > +	 * by bootloader or EEPROM.
> > +	 */
> > +	mgr->state = mgr->mops->state(mgr);
> 
> This is existing code, but it seems wrong.
> 
> A side effect of state() should not be to initialize.
> 
> An init() should be added to mops

Does a check for mops->state() solves this issue? like:

	if (mgr->mops->state)
		mgr->state = mgr->mpos->state(mgr);

This could be in a separate patch.

Thanks,
Yilun

> 
> > +
> > +	ret = device_register(&mgr->dev);
> > +	if (ret) {
> > +		put_device(&mgr->dev);
> > +		return ERR_PTR(ret);
> > +	}
> > +
> >   	return mgr;
> >   error_device:
> > @@ -612,96 +625,36 @@ struct fpga_manager *fpga_mgr_create(struct device *parent, const char *name,
> >   error_kfree:
> >   	kfree(mgr);
> > -	return NULL;
> > +	return ERR_PTR(ret);
> >   }
> > -EXPORT_SYMBOL_GPL(fpga_mgr_create);
> > +EXPORT_SYMBOL_GPL(fpga_mgr_register_full);
> >   /**
> > - * fpga_mgr_free - free an FPGA manager created with fpga_mgr_create()
> > - * @mgr:	fpga manager struct
> > - */
> > -void fpga_mgr_free(struct fpga_manager *mgr)
> > -{
> > -	ida_simple_remove(&fpga_mgr_ida, mgr->dev.id);
> > -	kfree(mgr);
> > -}
> > -EXPORT_SYMBOL_GPL(fpga_mgr_free);
> > -
> > -static void devm_fpga_mgr_release(struct device *dev, void *res)
> > -{
> > -	struct fpga_mgr_devres *dr = res;
> > -
> > -	fpga_mgr_free(dr->mgr);
> > -}
> > -
> > -/**
> > - * devm_fpga_mgr_create - create and initialize a managed FPGA manager struct
> > + * fpga_mgr_register - create and register an FPGA Manager device
> >    * @parent:	fpga manager device from pdev
> >    * @name:	fpga manager name
> >    * @mops:	pointer to structure of fpga manager ops
> >    * @priv:	fpga manager private data
> >    *
> > - * This function is intended for use in an FPGA manager driver's probe function.
> > - * After the manager driver creates the manager struct with
> > - * devm_fpga_mgr_create(), it should register it with fpga_mgr_register().  The
> > - * manager driver's remove function should call fpga_mgr_unregister().  The
> > - * manager struct allocated with this function will be freed automatically on
> > - * driver detach.  This includes the case of a probe function returning error
> > - * before calling fpga_mgr_register(), the struct will still get cleaned up.
> > + * The caller of this function is responsible for calling fpga_mgr_unregister().
> > + * Using devm_fpga_mgr_register() instead is recommended. This simple
> > + * version of the register function should be sufficient for most users. The
> > + * fpga_mgr_register_full() function is available for users that need to pass
> > + * additional, optional parameters.
> >    *
> > - * Return: pointer to struct fpga_manager or NULL
> > + * Return: pointer to struct fpga_manager pointer or ERR_PTR()
> >    */
> > -struct fpga_manager *devm_fpga_mgr_create(struct device *parent, const char *name,
> > -					  const struct fpga_manager_ops *mops,
> > -					  void *priv)
> > +struct fpga_manager *
> > +fpga_mgr_register(struct device *parent, const char *name,
> > +		  const struct fpga_manager_ops *mops, void *priv)
> >   {
> > -	struct fpga_mgr_devres *dr;
> > +	struct fpga_manager_info info = { 0 };
> > -	dr = devres_alloc(devm_fpga_mgr_release, sizeof(*dr), GFP_KERNEL);
> > -	if (!dr)
> > -		return NULL;
> > +	info.name = name;
> > +	info.mops = mops;
> > +	info.priv = priv;
> > -	dr->mgr = fpga_mgr_create(parent, name, mops, priv);
> > -	if (!dr->mgr) {
> > -		devres_free(dr);
> > -		return NULL;
> > -	}
> > -
> > -	devres_add(parent, dr);
> > -
> > -	return dr->mgr;
> > -}
> > -EXPORT_SYMBOL_GPL(devm_fpga_mgr_create);
> > -
> > -/**
> > - * fpga_mgr_register - register an FPGA manager
> > - * @mgr: fpga manager struct
> > - *
> > - * Return: 0 on success, negative error code otherwise.
> > - */
> > -int fpga_mgr_register(struct fpga_manager *mgr)
> > -{
> > -	int ret;
> > -
> > -	/*
> > -	 * Initialize framework state by requesting low level driver read state
> > -	 * from device.  FPGA may be in reset mode or may have been programmed
> > -	 * by bootloader or EEPROM.
> > -	 */
> > -	mgr->state = mgr->mops->state(mgr);
> > -
> > -	ret = device_add(&mgr->dev);
> > -	if (ret)
> > -		goto error_device;
> > -
> > -	dev_info(&mgr->dev, "%s registered\n", mgr->name);
> > -
> > -	return 0;
> > -
> > -error_device:
> > -	ida_simple_remove(&fpga_mgr_ida, mgr->dev.id);
> > -
> > -	return ret;
> > +	return fpga_mgr_register_full(parent, &info);
> >   }
> >   EXPORT_SYMBOL_GPL(fpga_mgr_register);
> > @@ -726,14 +679,6 @@ void fpga_mgr_unregister(struct fpga_manager *mgr)
> >   }
> >   EXPORT_SYMBOL_GPL(fpga_mgr_unregister);
> > -static int fpga_mgr_devres_match(struct device *dev, void *res,
> > -				 void *match_data)
> > -{
> > -	struct fpga_mgr_devres *dr = res;
> > -
> > -	return match_data == dr->mgr;
> > -}
> > -
> >   static void devm_fpga_mgr_unregister(struct device *dev, void *res)
> >   {
> >   	struct fpga_mgr_devres *dr = res;
> > @@ -742,45 +687,67 @@ static void devm_fpga_mgr_unregister(struct device *dev, void *res)
> >   }
> >   /**
> > - * devm_fpga_mgr_register - resource managed variant of fpga_mgr_register()
> > - * @dev: managing device for this FPGA manager
> > - * @mgr: fpga manager struct
> > + * devm_fpga_mgr_register_full - resource managed variant of fpga_mgr_register()
> > + * @parent:	fpga manager device from pdev
> > + * @info:	parameters for fpga manager
> >    *
> > - * This is the devres variant of fpga_mgr_register() for which the unregister
> > + * This is the devres variant of fpga_mgr_register_full() for which the unregister
> >    * function will be called automatically when the managing device is detached.
> >    */
> > -int devm_fpga_mgr_register(struct device *dev, struct fpga_manager *mgr)
> > +struct fpga_manager *
> > +devm_fpga_mgr_register_full(struct device *parent, const struct fpga_manager_info *info)
> >   {
> >   	struct fpga_mgr_devres *dr;
> > -	int ret;
> > -
> > -	/*
> > -	 * Make sure that the struct fpga_manager * that is passed in is
> > -	 * managed itself.
> > -	 */
> > -	if (WARN_ON(!devres_find(dev, devm_fpga_mgr_release,
> > -				 fpga_mgr_devres_match, mgr)))
> > -		return -EINVAL;
> > +	struct fpga_manager *mgr;
> >   	dr = devres_alloc(devm_fpga_mgr_unregister, sizeof(*dr), GFP_KERNEL);
> >   	if (!dr)
> > -		return -ENOMEM;
> > +		return ERR_PTR(-ENOMEM);
> > -	ret = fpga_mgr_register(mgr);
> > -	if (ret) {
> > +	mgr = fpga_mgr_register_full(parent, info);
> > +	if (IS_ERR(mgr)) {
> >   		devres_free(dr);
> > -		return ret;
> > +		return mgr;
> >   	}
> >   	dr->mgr = mgr;
> > -	devres_add(dev, dr);
> > +	devres_add(parent, dr);
> > -	return 0;
> > +	return mgr;
> > +}
> > +EXPORT_SYMBOL_GPL(devm_fpga_mgr_register_full);
> > +
> > +/**
> > + * devm_fpga_mgr_register - resource managed variant of fpga_mgr_register()
> > + * @parent:	fpga manager device from pdev
> > + * @name:	fpga manager name
> > + * @mops:	pointer to structure of fpga manager ops
> > + * @priv:	fpga manager private data
> > + *
> > + * This is the devres variant of fpga_mgr_register() for which the
> > + * unregister function will be called automatically when the managing
> > + * device is detached.
> > + */
> > +struct fpga_manager *
> > +devm_fpga_mgr_register(struct device *parent, const char *name,
> > +		       const struct fpga_manager_ops *mops, void *priv)
> > +{
> > +	struct fpga_manager_info info = { 0 };
> > +
> > +	info.name = name;
> > +	info.mops = mops;
> > +	info.priv = priv;
> > +
> > +	return devm_fpga_mgr_register_full(parent, &info);
> >   }
> >   EXPORT_SYMBOL_GPL(devm_fpga_mgr_register);
> >   static void fpga_mgr_dev_release(struct device *dev)
> >   {
> > +	struct fpga_manager *mgr = to_fpga_manager(dev);
> > +
> > +	ida_simple_remove(&fpga_mgr_ida, mgr->dev.id);
> > +	kfree(mgr);
> >   }
> >   static int __init fpga_mgr_class_init(void)
> > diff --git a/drivers/fpga/ice40-spi.c b/drivers/fpga/ice40-spi.c
> > index 69dec5af23c3..b7591912248f 100644
> > --- a/drivers/fpga/ice40-spi.c
> > +++ b/drivers/fpga/ice40-spi.c
> > @@ -178,12 +178,9 @@ static int ice40_fpga_probe(struct spi_device *spi)
> >   		return ret;
> >   	}
> > -	mgr = devm_fpga_mgr_create(dev, "Lattice iCE40 FPGA Manager",
> > -				   &ice40_fpga_ops, priv);
> > -	if (!mgr)
> > -		return -ENOMEM;
> > -
> > -	return devm_fpga_mgr_register(dev, mgr);
> > +	mgr = devm_fpga_mgr_register(dev, "Lattice iCE40 FPGA Manager",
> > +				     &ice40_fpga_ops, priv);
> > +	return PTR_ERR_OR_ZERO(mgr);
> >   }
> >   static const struct of_device_id ice40_fpga_of_match[] = {
> > diff --git a/drivers/fpga/machxo2-spi.c b/drivers/fpga/machxo2-spi.c
> > index 1afb41aa20d7..8469dfb5dd21 100644
> > --- a/drivers/fpga/machxo2-spi.c
> > +++ b/drivers/fpga/machxo2-spi.c
> > @@ -366,12 +366,9 @@ static int machxo2_spi_probe(struct spi_device *spi)
> >   		return -EINVAL;
> >   	}
> > -	mgr = devm_fpga_mgr_create(dev, "Lattice MachXO2 SPI FPGA Manager",
> > -				   &machxo2_ops, spi);
> > -	if (!mgr)
> > -		return -ENOMEM;
> > -
> > -	return devm_fpga_mgr_register(dev, mgr);
> > +	mgr = devm_fpga_mgr_register(dev, "Lattice MachXO2 SPI FPGA Manager",
> > +				     &machxo2_ops, spi);
> > +	return PTR_ERR_OR_ZERO(mgr);
> >   }
> >   #ifdef CONFIG_OF
> > diff --git a/drivers/fpga/socfpga-a10.c b/drivers/fpga/socfpga-a10.c
> > index 573d88bdf730..ac8e89b8a5cc 100644
> > --- a/drivers/fpga/socfpga-a10.c
> > +++ b/drivers/fpga/socfpga-a10.c
> > @@ -508,19 +508,15 @@ static int socfpga_a10_fpga_probe(struct platform_device *pdev)
> >   		return -EBUSY;
> >   	}
> > -	mgr = devm_fpga_mgr_create(dev, "SoCFPGA Arria10 FPGA Manager",
> > -				   &socfpga_a10_fpga_mgr_ops, priv);
> > -	if (!mgr)
> > -		return -ENOMEM;
> > -
> > -	platform_set_drvdata(pdev, mgr);
> > -
> > -	ret = fpga_mgr_register(mgr);
> > -	if (ret) {
> > +	mgr = fpga_mgr_register(dev, "SoCFPGA Arria10 FPGA Manager",
> > +				&socfpga_a10_fpga_mgr_ops, priv);
> > +	if (IS_ERR(mgr)) {
> >   		clk_disable_unprepare(priv->clk);
> > -		return ret;
> > +		return PTR_ERR(mgr);
> >   	}
> > +	platform_set_drvdata(pdev, mgr);
> > +
> >   	return 0;
> >   }
> > diff --git a/drivers/fpga/socfpga.c b/drivers/fpga/socfpga.c
> > index 1f467173fc1f..7e0741f99696 100644
> > --- a/drivers/fpga/socfpga.c
> > +++ b/drivers/fpga/socfpga.c
> > @@ -571,12 +571,9 @@ static int socfpga_fpga_probe(struct platform_device *pdev)
> >   	if (ret)
> >   		return ret;
> > -	mgr = devm_fpga_mgr_create(dev, "Altera SOCFPGA FPGA Manager",
> > -				   &socfpga_fpga_ops, priv);
> > -	if (!mgr)
> > -		return -ENOMEM;
> > -
> > -	return devm_fpga_mgr_register(dev, mgr);
> > +	mgr = devm_fpga_mgr_register(dev, "Altera SOCFPGA FPGA Manager",
> > +				     &socfpga_fpga_ops, priv);
> > +	return PTR_ERR_OR_ZERO(mgr);
> >   }
> >   #ifdef CONFIG_OF
> > diff --git a/drivers/fpga/stratix10-soc.c b/drivers/fpga/stratix10-soc.c
> > index a2cea500f7cc..9155e888a133 100644
> > --- a/drivers/fpga/stratix10-soc.c
> > +++ b/drivers/fpga/stratix10-soc.c
> > @@ -425,18 +425,11 @@ static int s10_probe(struct platform_device *pdev)
> >   	init_completion(&priv->status_return_completion);
> > -	mgr = fpga_mgr_create(dev, "Stratix10 SOC FPGA Manager",
> > -			      &s10_ops, priv);
> > -	if (!mgr) {
> > -		dev_err(dev, "unable to create FPGA manager\n");
> > -		ret = -ENOMEM;
> > -		goto probe_err;
> > -	}
> > -
> > -	ret = fpga_mgr_register(mgr);
> > -	if (ret) {
> > +	mgr = fpga_mgr_register(dev, "Stratix10 SOC FPGA Manager",
> > +				&s10_ops, priv);
> > +	if (IS_ERR(mgr)) {
> >   		dev_err(dev, "unable to register FPGA manager\n");
> > -		fpga_mgr_free(mgr);
> > +		ret = PTR_ERR(mgr);
> >   		goto probe_err;
> >   	}
> > @@ -454,7 +447,6 @@ static int s10_remove(struct platform_device *pdev)
> >   	struct s10_priv *priv = mgr->priv;
> >   	fpga_mgr_unregister(mgr);
> > -	fpga_mgr_free(mgr);
> >   	stratix10_svc_free_channel(priv->chan);
> >   	return 0;
> > diff --git a/drivers/fpga/ts73xx-fpga.c b/drivers/fpga/ts73xx-fpga.c
> > index 101f016c6ed8..fd52de20ddb2 100644
> > --- a/drivers/fpga/ts73xx-fpga.c
> > +++ b/drivers/fpga/ts73xx-fpga.c
> > @@ -122,12 +122,9 @@ static int ts73xx_fpga_probe(struct platform_device *pdev)
> >   	if (IS_ERR(priv->io_base))
> >   		return PTR_ERR(priv->io_base);
> > -	mgr = devm_fpga_mgr_create(kdev, "TS-73xx FPGA Manager",
> > -				   &ts73xx_fpga_ops, priv);
> > -	if (!mgr)
> > -		return -ENOMEM;
> > -
> > -	return devm_fpga_mgr_register(kdev, mgr);
> > +	mgr = devm_fpga_mgr_register(kdev, "TS-73xx FPGA Manager",
> > +				     &ts73xx_fpga_ops, priv);
> > +	return PTR_ERR_OR_ZERO(mgr);
> >   }
> >   static struct platform_driver ts73xx_fpga_driver = {
> > diff --git a/drivers/fpga/xilinx-spi.c b/drivers/fpga/xilinx-spi.c
> > index fee4d0abf6bf..db23626f9ab2 100644
> > --- a/drivers/fpga/xilinx-spi.c
> > +++ b/drivers/fpga/xilinx-spi.c
> > @@ -247,13 +247,10 @@ static int xilinx_spi_probe(struct spi_device *spi)
> >   		return dev_err_probe(&spi->dev, PTR_ERR(conf->done),
> >   				     "Failed to get DONE gpio\n");
> > -	mgr = devm_fpga_mgr_create(&spi->dev,
> > -				   "Xilinx Slave Serial FPGA Manager",
> > -				   &xilinx_spi_ops, conf);
> > -	if (!mgr)
> > -		return -ENOMEM;
> > -
> > -	return devm_fpga_mgr_register(&spi->dev, mgr);
> > +	mgr = devm_fpga_mgr_register(&spi->dev,
> > +				     "Xilinx Slave Serial FPGA Manager",
> > +				     &xilinx_spi_ops, conf);
> > +	return PTR_ERR_OR_ZERO(mgr);
> >   }
> >   static const struct of_device_id xlnx_spi_of_match[] = {
> > diff --git a/drivers/fpga/zynq-fpga.c b/drivers/fpga/zynq-fpga.c
> > index 9b75bd4f93d8..426aa34c6a0d 100644
> > --- a/drivers/fpga/zynq-fpga.c
> > +++ b/drivers/fpga/zynq-fpga.c
> > @@ -609,20 +609,16 @@ static int zynq_fpga_probe(struct platform_device *pdev)
> >   	clk_disable(priv->clk);
> > -	mgr = devm_fpga_mgr_create(dev, "Xilinx Zynq FPGA Manager",
> > -				   &zynq_fpga_ops, priv);
> > -	if (!mgr)
> > -		return -ENOMEM;
> > -
> > -	platform_set_drvdata(pdev, mgr);
> > -
> > -	err = fpga_mgr_register(mgr);
> > -	if (err) {
> > +	mgr = fpga_mgr_register(dev, "Xilinx Zynq FPGA Manager",
> > +				&zynq_fpga_ops, priv);
> > +	if (IS_ERR(mgr)) {
> >   		dev_err(dev, "unable to register FPGA manager\n");
> >   		clk_unprepare(priv->clk);
> > -		return err;
> > +		return PTR_ERR(mgr);
> >   	}
> > +	platform_set_drvdata(pdev, mgr);
> > +
> >   	return 0;
> >   }
> > diff --git a/drivers/fpga/zynqmp-fpga.c b/drivers/fpga/zynqmp-fpga.c
> > index 125743c9797f..975bdc4d0a65 100644
> > --- a/drivers/fpga/zynqmp-fpga.c
> > +++ b/drivers/fpga/zynqmp-fpga.c
> > @@ -102,12 +102,9 @@ static int zynqmp_fpga_probe(struct platform_device *pdev)
> >   	priv->dev = dev;
> > -	mgr = devm_fpga_mgr_create(dev, "Xilinx ZynqMP FPGA Manager",
> > -				   &zynqmp_fpga_ops, priv);
> > -	if (!mgr)
> > -		return -ENOMEM;
> > -
> > -	return devm_fpga_mgr_register(dev, mgr);
> > +	mgr = devm_fpga_mgr_register(dev, "Xilinx ZynqMP FPGA Manager",
> > +				     &zynqmp_fpga_ops, priv);
> > +	return PTR_ERR_OR_ZERO(mgr);
> >   }
> >   static const struct of_device_id zynqmp_fpga_of_match[] = {
> > diff --git a/include/linux/fpga/fpga-mgr.h b/include/linux/fpga/fpga-mgr.h
> > index 474c1f506307..ac3ddaf2903c 100644
> > --- a/include/linux/fpga/fpga-mgr.h
> > +++ b/include/linux/fpga/fpga-mgr.h
> > @@ -105,6 +105,36 @@ struct fpga_image_info {
> >   #endif
> >   };
> > +/**
> > + * struct fpga_compat_id - id for compatibility check
> > + *
> > + * @id_h: high 64bit of the compat_id
> > + * @id_l: low 64bit of the compat_id
> > + */
> > +struct fpga_compat_id {
> > +	u64 id_h;
> > +	u64 id_l;
> > +};
> > +
> 
> There are two register functions are to handle this dfl only structure.
> 
> This really needs to be moved fme_mgr_priv.
> 
> > +/**
> > + * struct fpga_manager_info - collection of parameters for an FPGA Manager
> > + * @name: fpga manager name
> > + * @compat_id: FPGA manager id for compatibility check.
> > + * @mops: pointer to structure of fpga manager ops
> > + * @priv: fpga manager private data
> > + *
> > + * fpga_manager_info contains parameters for the register function. These
> > + * are separated into an info structure because they some are optional
> > + * others could be added to in the future. The info structure facilitates
> > + * maintaining a stable API.
> > + */
> > +struct fpga_manager_info {
> > +	const char *name;
> > +	struct fpga_compat_id *compat_id;
> > +	const struct fpga_manager_ops *mops;
> > +	void *priv;
> > +};
> > +
> >   /**
> >    * struct fpga_manager_ops - ops for low level fpga manager drivers
> >    * @initial_header_size: Maximum number of bytes that should be passed into write_init
> > @@ -143,17 +173,6 @@ struct fpga_manager_ops {
> >   #define FPGA_MGR_STATUS_IP_PROTOCOL_ERR		BIT(3)
> >   #define FPGA_MGR_STATUS_FIFO_OVERFLOW_ERR	BIT(4)
> > -/**
> > - * struct fpga_compat_id - id for compatibility check
> > - *
> > - * @id_h: high 64bit of the compat_id
> > - * @id_l: low 64bit of the compat_id
> > - */
> > -struct fpga_compat_id {
> > -	u64 id_h;
> > -	u64 id_l;
> > -};
> > -
> >   /**
> >    * struct fpga_manager - fpga manager structure
> >    * @name: name of low level fpga manager
> > @@ -191,17 +210,18 @@ struct fpga_manager *fpga_mgr_get(struct device *dev);
> >   void fpga_mgr_put(struct fpga_manager *mgr);
> > -struct fpga_manager *fpga_mgr_create(struct device *dev, const char *name,
> > -				     const struct fpga_manager_ops *mops,
> > -				     void *priv);
> > -void fpga_mgr_free(struct fpga_manager *mgr);
> 
> removing these should cause any oot driver to fail to load.
> 
> so an oops is unlikely.
> 
> I'm ok with with api change.
> 
> > -int fpga_mgr_register(struct fpga_manager *mgr);
> > -void fpga_mgr_unregister(struct fpga_manager *mgr);
> > +struct fpga_manager *
> > +fpga_mgr_register_full(struct device *parent, const struct fpga_manager_info *info);
> > -int devm_fpga_mgr_register(struct device *dev, struct fpga_manager *mgr);
> > +struct fpga_manager *
> > +fpga_mgr_register(struct device *parent, const char *name,
> > +		  const struct fpga_manager_ops *mops, void *priv);
> 
> having 2 ways to do the same thing is not great.
> 
> this should be reduced down to 1.
> 
> My preference is for the *info one as it's api will be durable.
> 
> Tom
> 
> > +void fpga_mgr_unregister(struct fpga_manager *mgr);
> > -struct fpga_manager *devm_fpga_mgr_create(struct device *dev, const char *name,
> > -					  const struct fpga_manager_ops *mops,
> > -					  void *priv);
> > +struct fpga_manager *
> > +devm_fpga_mgr_register_full(struct device *parent, const struct fpga_manager_info *info);
> > +struct fpga_manager *
> > +devm_fpga_mgr_register(struct device *parent, const char *name,
> > +		       const struct fpga_manager_ops *mops, void *priv);
> >   #endif /*_LINUX_FPGA_MGR_H */