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

[Russ Weight <russell.h.weight@intel.com>]

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?

>
> 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 */
>