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 02:02:20PM -0700, Russ Weight wrote:
> 
> 
> On 7/6/21 12:04 PM, Tom Rix wrote:
> > Russ,
> >
> > My two big concerns are.
> >
> > compat_id does not belong in fpga_mgr_info, it belongs in fme_mgr_priv.
> 
> fpga_mgr_info is a temporary structure on the stack that contains the
> parameters only long enough to pass them in and have them added to the
> fpga_manager structure. Do you have a concern about it being on the
> fpga_manager structure.
> 
> >
> > there are two register functions, there should be one.
> 
> I get what you are saying. I don't really like the idea of forcing the
> complexity of the temporary structure on all callers, since only a
> couple require it, but we can do that if that is the concensus.
> 
> What do others think?

The _register_full() function takes care of everything, but it do adds
the complexity for all callers. A simpler version makes their life
easier.

2 register functions is OK to me, as there are some examples in other
subsystems, some of them even have 3 or more register functions.

Thanks,
Yilun

> 
> >
> > 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 ?
> 
> The compat_id is used to verify compatibility between the static region and
> the partial reconfiguration. If there is insufficient memory for the small
> data structure, I think it is best to fail here. This is also consistent
> current implementation.
>  
> >>   -    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
> 
> I think this is just capturing the state of the underlying device an
> reflecting it in the fpga-manager state? Maybe someone else can comment
> on this. It seems outside the scope of these patches.
> 
> >
> >> +
> >> +    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.
> 
> I would like to see if other's agree.
> 
> >
> > 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 */
> >