linux-kernel - Re: [PATCH v4 05/15] drivers: platform: add fwnode base platform devices retrieval

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Date:   Mon, 5 Sep 2016 21:19:43 +0800
From:   Hanjun Guo <hanjun.guo@...aro.org>
To:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        iommu@...ts.linux-foundation.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Will Deacon <will.deacon@....com>,
        Marc Zyngier <marc.zyngier@....com>,
        Robin Murphy <robin.murphy@....com>,
        Joerg Roedel <joro@...tes.org>,
        Tomasz Nowicki <tn@...ihalf.com>, Jon Masters <jcm@...hat.com>,
        Sinan Kaya <okaya@...eaurora.org>,
        Nate Watterson <nwatters@...eaurora.org>,
        Dennis Chen <dennis.chen@....com>, linux-acpi@...r.kernel.org,
        linux-pci@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v4 05/15] drivers: platform: add fwnode base platform
 devices retrieval

On 2016/8/15 23:23, Lorenzo Pieralisi wrote:
> The platform device kernel API does not provide functions to
> retrieve a platform device through the corresponding struct
> device fwnode pointer.
>
> Implement the fwnode platform_device look-up in drivers core
> code by using the bus_find_device() API and a corresponding
> matching function. The OF equivalent (eg of_find_device_by_node())
> will reuse the newly introduced function when OF code will
> take care of setting up the device->fwnode value that is
> currently left dangling for platform devices instantiated out
> of device tree nodes.
>
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>
> ---
>  drivers/base/platform.c         | 23 +++++++++++++++++++++++
>  include/linux/platform_device.h |  3 +++
>  2 files changed, 26 insertions(+)
>
> diff --git a/drivers/base/platform.c b/drivers/base/platform.c
> index 6482d47..3ef150d 100644
> --- a/drivers/base/platform.c
> +++ b/drivers/base/platform.c
> @@ -760,6 +760,29 @@ err_out:
>  }
>  EXPORT_SYMBOL_GPL(__platform_create_bundle);
>
> +static int fwnode_dev_match(struct device *dev, void *data)
> +{
> +	return dev->fwnode == data;
> +}
> +
> +/**
> + * platform_find_device_by_fwnode() - Find the platform_device associated
> + *				      with a fwnode
> + * @fwnode: Pointer to firmware node
> + *
> + * Returns platform_device pointer, or NULL if not found
> + */
> +struct platform_device *
> +platform_find_device_by_fwnode(struct fwnode_handle *fwnode)
> +{
> +	struct device *dev;
> +
> +	dev = bus_find_device(&platform_bus_type, NULL, fwnode,
> +			      fwnode_dev_match);
> +	return dev ? to_platform_device(dev) : NULL;
> +}
> +EXPORT_SYMBOL(platform_find_device_by_fwnode);

As SMMU is registered as platform devices, I think we need such
API to retrieve the platform device with fwnode handle, actually
Kefeng introduced a similar patch [1], but your patch is more
generic, so this patch make sense to me,

Reviewed-by: Hanjun Guo <hanjun.guo@...aro.org>

Thanks
Hanjun

[1]: https://patchwork.kernel.org/patch/7743661/