Re: [PATCH v4 1/3] fpga: mgr: Use standard dev_release for class driver

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

On 6/1/21 5:38 PM, Russ Weight wrote:
>
> On 6/1/21 4:24 PM, Tom Rix wrote:
>> On 5/28/21 2:57 PM, Russ Weight wrote:
>>> The FPGA manager class driver data structure is being treated as a
>>> managed resource instead of using standard dev_release call-back
>>> 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() function.
>>>
>>> The devm_fpga_mgr_register() function is retained.
>>>
>>> Signed-off-by: Russ Weight <russell.h.weight@intel.com>
>>> ---
>>> v4:
>>>    - Added the compat_id parameter to fpga_mgr_register() and
>> On a refactor, it is best to do the refactoring as mechanically as possible.
>>
>> While compat_id may be useful, it should be done in a separate patch.
> These would have to be included with the changes merge the create and register
> functions into a single function.
>
>>
>> Unless it is really needed for your next security update patch consider resubmitting later
>>
>>>      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.
>>> ---
>>>   drivers/fpga/altera-cvp.c        |  12 +--
>>>   drivers/fpga/altera-pr-ip-core.c |   9 +-
>>>   drivers/fpga/altera-ps-spi.c     |  10 +-
>>>   drivers/fpga/dfl-fme-mgr.c       |  12 +--
>>>   drivers/fpga/fpga-mgr.c          | 168 +++++++++----------------------
>>>   drivers/fpga/ice40-spi.c         |  10 +-
>>>   drivers/fpga/machxo2-spi.c       |  10 +-
>>>   drivers/fpga/socfpga-a10.c       |  16 ++-
>>>   drivers/fpga/socfpga.c           |  10 +-
>>>   drivers/fpga/stratix10-soc.c     |  15 +--
>>>   drivers/fpga/ts73xx-fpga.c       |  10 +-
>>>   drivers/fpga/xilinx-spi.c        |  12 +--
>>>   drivers/fpga/zynq-fpga.c         |  16 ++-
>>>   drivers/fpga/zynqmp-fpga.c       |  10 +-
>>>   include/linux/fpga/fpga-mgr.h    |  19 ++--
>>>   15 files changed, 120 insertions(+), 219 deletions(-)
>> ./Documentation/driver-api/fpga/fpga-mgr.rst
>>
>> still refers to fpga_mgr_create.
> Thanks for catching that.
>
>>> diff --git a/drivers/fpga/altera-cvp.c b/drivers/fpga/altera-cvp.c
>>> index 4e0edb60bfba..25eaa97ae7aa 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, NULL,
>>> +                &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 5b130c4d9882..bfd4de1e7ac5 100644
>>> --- a/drivers/fpga/altera-pr-ip-core.c
>>> +++ b/drivers/fpga/altera-pr-ip-core.c
>>> @@ -191,11 +191,12 @@ 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;
>>> +    mgr = devm_fpga_mgr_register(dev, dev_name(dev), NULL,
>>> +                     &alt_pr_ops, priv);
>>> +    if (IS_ERR(mgr))
>>> +        return PTR_ERR(mgr);
>>>   -    return devm_fpga_mgr_register(dev, mgr);
>>> +    return 0;
>>>   }
>>>   EXPORT_SYMBOL_GPL(alt_pr_register);
>>>   diff --git a/drivers/fpga/altera-ps-spi.c b/drivers/fpga/altera-ps-spi.c
>>> index 23bfd4d1ad0f..e6fc7208213c 100644
>>> --- a/drivers/fpga/altera-ps-spi.c
>>> +++ b/drivers/fpga/altera-ps-spi.c
>>> @@ -302,12 +302,12 @@ 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;
>>> +    mgr = devm_fpga_mgr_register(&spi->dev, conf->mgr_name, NULL,
>>> +                     &altera_ps_ops, conf);
>>> +    if (IS_ERR(mgr))
>>> +        return PTR_ERR(mgr);
>>>   -    return devm_fpga_mgr_register(&spi->dev, mgr);
>>> +    return 0;
>>>   }
>>>     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..c9b98afa7d50 100644
>>> --- a/drivers/fpga/dfl-fme-mgr.c
>>> +++ b/drivers/fpga/dfl-fme-mgr.c
>>> @@ -308,14 +308,12 @@ static int fme_mgr_probe(struct platform_device *pdev)
>>>         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;
>>> +    mgr = devm_fpga_mgr_register(dev, "DFL FME FPGA Manager", compat_id,
>>> +                     &fme_mgr_ops, priv);
>>> +    if (IS_ERR(mgr))
>>> +        return PTR_ERR(mgr);
>>>   -    return devm_fpga_mgr_register(dev, mgr);
>>> +    return 0;
>>>   }
>>>     static struct platform_driver fme_mgr_driver = {
>>> diff --git a/drivers/fpga/fpga-mgr.c b/drivers/fpga/fpga-mgr.c
>>> index b85bc47c91a9..d6d64ce34417 100644
>>> --- a/drivers/fpga/fpga-mgr.c
>>> +++ b/drivers/fpga/fpga-mgr.c
>>> @@ -550,20 +550,22 @@ void fpga_mgr_unlock(struct fpga_manager *mgr)
>>>   EXPORT_SYMBOL_GPL(fpga_mgr_unlock);
>>>     /**
>>> - * fpga_mgr_create - create and initialize a FPGA manager struct
>>> + * fpga_mgr_register - create and register a FPGA Manager device
>>>    * @dev:    fpga manager device from pdev
>>>    * @name:    fpga manager name
>>> + * @compat_id:    FPGA manager id for compatibility check.
>> for consistency, use lowercase fpga
>>
>> similar issue below.
> OK
>
>>>    * @mops:    pointer to structure of fpga manager ops
>>>    * @priv:    fpga manager private data
>>>    *
>>> - * 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 instead is recommended.
>>>    *
>>> - * Return: pointer to struct fpga_manager or NULL
>>> + * Return: struct fpga_manager pointer on success, ERR_PTR() on error.
>>>    */
>>> -struct fpga_manager *fpga_mgr_create(struct device *dev, const char *name,
>>> -                     const struct fpga_manager_ops *mops,
>>> -                     void *priv)
>>> +struct fpga_manager *
>>> +fpga_mgr_register(struct device *dev, const char *name,
>>> +          struct fpga_compat_id *compat_id,
>>> +          const struct fpga_manager_ops *mops, void *priv)
>>>   {
>>>       struct fpga_manager *mgr;
>>>       int id, ret;
>>> @@ -572,29 +574,31 @@ struct fpga_manager *fpga_mgr_create(struct device *dev, const char *name,
>>>           !mops->write_init || (!mops->write && !mops->write_sg) ||
>>>           (mops->write && mops->write_sg)) {
>>>           dev_err(dev, "Attempt to register without fpga_manager_ops\n");
>>> -        return NULL;
>>> +        return ERR_PTR(-EINVAL);
>>>       }
>>>         if (!name || !strlen(name)) {
>>>           dev_err(dev, "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;
>> ida_* returns a normal error, so needs a wrapping in
>>
>> ret = ERR_PTR(id)
> Thanks - I'll fix that
Actually, if you follow the "goto error_kfree", you will see that ret is
wrapped in ERR_PTR() in the return statement, so id does not need to be
wrapped here.

>
>>>           goto error_kfree;
>>> +    }
>>>         mutex_init(&mgr->ref_mutex);
>>>         mgr->name = name;
>>> +    mgr->compat_id = compat_id;
>>>       mgr->mops = mops;
>>>       mgr->priv = priv;
>>>   -    device_initialize(&mgr->dev);
>>>       mgr->dev.class = fpga_mgr_class;
>>>       mgr->dev.groups = mops->groups;
>>>       mgr->dev.parent = dev;
>>> @@ -605,84 +609,6 @@ struct fpga_manager *fpga_mgr_create(struct device *dev, const char *name,
>>>       if (ret)
>>>           goto error_device;
>>>   -    return mgr;
>>> -
>>> -error_device:
>>> -    ida_simple_remove(&fpga_mgr_ida, id);
>>> -error_kfree:
>>> -    kfree(mgr);
>>> -
>>> -    return NULL;
>>> -}
>>> -EXPORT_SYMBOL_GPL(fpga_mgr_create);
>>> -
>>> -/**
>>> - * fpga_mgr_free - free a 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
>>> - * @dev:    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 a 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.
>>> - *
>>> - * Return: pointer to struct fpga_manager or NULL
>>> - */
>>> -struct fpga_manager *devm_fpga_mgr_create(struct device *dev, const char *name,
>>> -                      const struct fpga_manager_ops *mops,
>>> -                      void *priv)
>>> -{
>>> -    struct fpga_mgr_devres *dr;
>>> -
>>> -    dr = devres_alloc(devm_fpga_mgr_release, sizeof(*dr), GFP_KERNEL);
>>> -    if (!dr)
>>> -        return NULL;
>>> -
>>> -    dr->mgr = fpga_mgr_create(dev, name, mops, priv);
>>> -    if (!dr->mgr) {
>>> -        devres_free(dr);
>>> -        return NULL;
>>> -    }
>>> -
>>> -    devres_add(dev, dr);
>>> -
>>> -    return dr->mgr;
>>> -}
>>> -EXPORT_SYMBOL_GPL(devm_fpga_mgr_create);
>>> -
>>> -/**
>>> - * fpga_mgr_register - register a 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
>>> @@ -690,18 +616,20 @@ int fpga_mgr_register(struct fpga_manager *mgr)
>>>        */
>>>       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);
>> can we keep this dev_info() line and move it below device_register() ?
> In Greg's response to my driver, he said he said that a well-behaved driver does
> not need dev_info() calls...
>>> +    ret = device_register(&mgr->dev);
>>> +    if (ret) {
>>> +        put_device(&mgr->dev);
>> pr_err() here ?
> OK - I can add a message
>
>>> +        return ERR_PTR(ret);
>>> +    }
>>>   -    return 0;
>>> +    return mgr;
>>>     error_device:
>>> -    ida_simple_remove(&fpga_mgr_ida, mgr->dev.id);
>>> +    ida_simple_remove(&fpga_mgr_ida, id);
>>> +error_kfree:
>>> +    kfree(mgr);
>>>   -    return ret;
>>> +    return ERR_PTR(ret);
>>>   }
>>>   EXPORT_SYMBOL_GPL(fpga_mgr_register);
>>>   @@ -726,14 +654,6 @@ 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;
>>> @@ -743,44 +663,46 @@ 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
>>> + * @dev:    fpga manager device from pdev
>>> + * @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
>>>    *
>>>    * This is the devres variant of fpga_mgr_register() 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(struct device *dev, const char *name,
>>> +               struct fpga_compat_id *compat_id,
>>> +               const struct fpga_manager_ops *mops, void *priv)
>>>   {
>>>       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(dev, name, compat_id, mops, priv);
>>> +    if (IS_ERR(mgr)) {
>>>           devres_free(dr);
>>> -        return ret;
>>> +        return mgr;
>>>       }
>>>         dr->mgr = mgr;
>>>       devres_add(dev, dr);
>>>   -    return 0;
>>> +    return mgr;
>>>   }
>>>   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..b1c7c0713e11 100644
>>> --- a/drivers/fpga/ice40-spi.c
>>> +++ b/drivers/fpga/ice40-spi.c
>>> @@ -178,12 +178,12 @@ 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;
>>> +    mgr = devm_fpga_mgr_register(dev, "Lattice iCE40 FPGA Manager",
>>> +                     NULL, &ice40_fpga_ops, priv);
>>> +    if (IS_ERR(mgr))
>>> +        return PTR_ERR(mgr);
>>>   -    return devm_fpga_mgr_register(dev, mgr);
>>> +    return 0;
>>>   }
>>>     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 114a64d2b7a4..75cc6efaa1b6 100644
>>> --- a/drivers/fpga/machxo2-spi.c
>>> +++ b/drivers/fpga/machxo2-spi.c
>>> @@ -366,12 +366,12 @@ 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;
>>> +    mgr = devm_fpga_mgr_register(dev, "Lattice MachXO2 SPI FPGA Manager",
>>> +                     NULL, &machxo2_ops, spi);
>>> +    if (IS_ERR(mgr))
>>> +        return PTR_ERR(mgr);
>>>   -    return devm_fpga_mgr_register(dev, mgr);
>>> +    return 0;
>>>   }
>>>     static const struct of_device_id of_match[] = {
>>> diff --git a/drivers/fpga/socfpga-a10.c b/drivers/fpga/socfpga-a10.c
>>> index 573d88bdf730..80b8891fb302 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",
>>> +                NULL, &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..06edfab8a496 100644
>>> --- a/drivers/fpga/socfpga.c
>>> +++ b/drivers/fpga/socfpga.c
>>> @@ -571,12 +571,12 @@ 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;
>>> +    mgr = devm_fpga_mgr_register(dev, "Altera SOCFPGA FPGA Manager",
>>> +                     NULL, &socfpga_fpga_ops, priv);
>>> +    if (IS_ERR(mgr))
>>> +        return PTR_ERR(mgr);
>>>   -    return devm_fpga_mgr_register(dev, mgr);
>>> +    return 0;
>>>   }
>>>     #ifdef CONFIG_OF
>>> diff --git a/drivers/fpga/stratix10-soc.c b/drivers/fpga/stratix10-soc.c
>>> index 657a70c5fc99..434094c3ac69 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",
>>> +                NULL, &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;
>>>       }
>>>   diff --git a/drivers/fpga/ts73xx-fpga.c b/drivers/fpga/ts73xx-fpga.c
>>> index 101f016c6ed8..5efbec2b9f9f 100644
>>> --- a/drivers/fpga/ts73xx-fpga.c
>>> +++ b/drivers/fpga/ts73xx-fpga.c
>>> @@ -122,12 +122,12 @@ 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;
>>> +    mgr = devm_fpga_mgr_register(kdev, "TS-73xx FPGA Manager",
>> This is missing compat_id param.
> Thanks - I thought I'll do another pass and make sure I catch them all.
>
>> Similar for others.
>>
>>> +                     &ts73xx_fpga_ops, priv);
>>> +    if (IS_ERR(mgr))
>>> +        return PTR_ERR(mgr);
>>>   -    return devm_fpga_mgr_register(kdev, mgr);
>>> +    return 0;
>>>   }
>>>     static struct platform_driver ts73xx_fpga_driver = {
>>> diff --git a/drivers/fpga/xilinx-spi.c b/drivers/fpga/xilinx-spi.c
>>> index fee4d0abf6bf..6f1894929687 100644
>>> --- a/drivers/fpga/xilinx-spi.c
>>> +++ b/drivers/fpga/xilinx-spi.c
>>> @@ -247,13 +247,13 @@ 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;
>>> +    mgr = devm_fpga_mgr_register(&spi->dev,
>>> +                     "Xilinx Slave Serial FPGA Manager",
>>> +                     NULL, &xilinx_spi_ops, conf);
>>> +    if (IS_ERR(mgr))
>>> +        return PTR_ERR(mgr);
>>>   -    return devm_fpga_mgr_register(&spi->dev, mgr);
>>> +    return 0;
>>>   }
>>>     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 07fa8d9ec675..74bbb9710f4e 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",
>> This is missing compat_id param as well.
>>> +                &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..1a6d520985be 100644
>>> --- a/drivers/fpga/zynqmp-fpga.c
>>> +++ b/drivers/fpga/zynqmp-fpga.c
>>> @@ -102,12 +102,12 @@ 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;
>>> +    mgr = devm_fpga_mgr_register(dev, "Xilinx ZynqMP FPGA Manager",
>>> +                     &zynqmp_fpga_ops, priv);
>>> +    if (IS_ERR(mgr))
>>> +        return PTR_ERR(mgr);
>>>   -    return devm_fpga_mgr_register(dev, mgr);
>>> +    return 0;
>>>   }
>>>     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 2bc3030a69e5..3e1859cc0640 100644
>>> --- a/include/linux/fpga/fpga-mgr.h
>>> +++ b/include/linux/fpga/fpga-mgr.h
>>> @@ -191,17 +191,16 @@ 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);
>> My biggest concern is that removing this will break all oot fpga drivers.
>>
>> The other patches have similar api changes
>>
>> Having a stable api is very important.
> That is a good point. While Greg did call out the separation of the
> device_initialize() and device_add() calls, his biggest concern was with
> the empty dev_release() functions. Maybe it would be best to first submit
> a patch that only addresses the dev_release() functions? Maybe it would be
> OK to leave the create and register functions as separate functions in order
> to maintain a stable API...

On further investigation, I don't think we have much choice in changing
the API. We are almost coming full circle here. In 2018, there was only
an fpga_mgr_register() function. It was returning an errno value or zero.
It was also setting the drvdata of the parent driver with a pointer to
the resulting fpga_manager structure.

It looks like the reason the interface was split into two (create and
register) was so that the fpga_manager pointer could be returned (by the
create function) without writing the drvdata of the parent driver:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7085e2a94f7df5f419e3cfb2fe809ce6564e9629

When the interfaces were split, fpga_mgr_free() was also created to free
the memory if the register function was not called. The fpga_mgr_free()
function was also called by the fpga_mgr_dev_release() function. A later
patch was submitted to simplify the memory management for the class driver:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=084181fe8cc7472695b907f0018f4cd00934cb12

It is this second commit that empties the fpga_mgr_dev_release() function
and instead uses devm_fpga_mgr_create() to manage the memory for the class
driver.

The fix I am proposing essentially takes us back to the 2018 implementation,
but returns the fpga_manager pointer or ERR_PTR() instead of returning zero or
an errno.

The definition of the API is integral to the memory management issue. I cannot
think of an acceptable solution for the upstream that doesn't involve
changing the API. It could result in some ifdef's in an out-of-tree driver,
but I don't think we can avoid it in this case.

> - Russ
>
>> My recommendation is to keep the public api and hide the change with an exported but not public function.
>>
>> Tom
>>
>>> -void fpga_mgr_free(struct fpga_manager *mgr);
>>> -int fpga_mgr_register(struct fpga_manager *mgr);
>>> +struct fpga_manager *fpga_mgr_register(struct device *dev, const char *name,
>>> +                       struct fpga_compat_id *compat_id,
>>> +                       const struct fpga_manager_ops *mops,
>>> +                       void *priv);
>>>   void fpga_mgr_unregister(struct fpga_manager *mgr);
>>>   -int devm_fpga_mgr_register(struct device *dev, 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(struct device *dev, const char *name,
>>> +               struct fpga_compat_id *compat_id,
>>> +               const struct fpga_manager_ops *mops,
>>> +               void *priv);
>>>     #endif /*_LINUX_FPGA_MGR_H */