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SubjectRe: [RFC] [PATCH] mfd: Fetch cell pointer from platform_device->mfd_cell
This looks fine to me; just some minor points below.

On
Fri, 8 Apr 2011 02:40:09 +0200 Samuel Ortiz <sameo@linux.intel.com>
wrote:

>
> In order for MFD drivers to fetch their cell pointer but also their
> platform data one, an mfd cell pointer is t aed to the
> platform_device structure.
> That allows all MFD sub devices drivers to be MFD agnostic, unless
> they really need to access their MFD cell data. Most of them don't,
> especially the ones for IPs used by both MFD and non MFD SoCs.
>
> Cc: Greg KH <gregkh@suse.de>
> Cc: Grant Likely <grant.likely@secretlab.ca>
> Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
> ---
> drivers/base/platform.c | 1 +
> drivers/mfd/mfd-core.c | 16 ++++++++++++++--
> include/linux/mfd/core.h | 8 ++++++--
> include/linux/platform_device.h | 5 +++++
> 4 files changed, 26 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/base/platform.c b/drivers/base/platform.c
> index f051cff..6c3a2bd 100644
> --- a/drivers/base/platform.c
> +++ b/drivers/base/platform.c
> @@ -149,6 +149,7 @@ static void platform_device_release(struct device
> *dev)
> of_device_node_put(&pa->pdev.dev);
> kfree(pa->pdev.dev.platform_data);
> + kfree(pa->pdev.mfd_cell);

Hm, given that most platform devices won't be mfd devices (and thus
mfd_cell will be NULL), is it better to rely on kfree's
unlikely(ZERO_OR_NULL_PTR(...)), or have this be "if
(pa->pdev.mfd_cell) kfree(pa->pdev.mfd_cell);"?

> kfree(pa->pdev.resource);
> kfree(pa);
> }
> diff --git a/drivers/mfd/mfd-core.c b/drivers/mfd/mfd-core.c
> index d01574d..f4c8c84 100644
> --- a/drivers/mfd/mfd-core.c
> +++ b/drivers/mfd/mfd-core.c
> @@ -55,6 +55,19 @@ int mfd_cell_disable(struct platform_device *pdev)
> }
> EXPORT_SYMBOL(mfd_cell_disable);
>
> +static int mfd_platform_add_cell(struct platform_device *pdev,
> + const struct mfd_cell *cell)
> +{
> + if (!cell)
> + return 0;
> +
> + pdev->mfd_cell = kmemdup(cell, sizeof(*cell), GFP_KERNEL);
> + if (!pdev->mfd_cell)
> + return -ENOMEM;
> +
> + return 0;
> +}
> +
> static int mfd_add_device(struct device *parent, int id,
> const struct mfd_cell *cell,
> struct resource *mem_base,
> @@ -75,7 +88,7 @@ static int mfd_add_device(struct device *parent,
> int id,
> pdev->dev.parent = parent;
>
> - ret = platform_device_add_data(pdev, cell, sizeof(*cell));
> + ret = mfd_platform_add_cell(pdev, cell);
> if (ret)
> goto fail_res;
>
> @@ -123,7 +136,6 @@ static int mfd_add_device(struct device *parent,
> int id,
> return 0;
>
> -/* platform_device_del(pdev); */
> fail_res:
> kfree(res);
> fail_device:
> diff --git a/include/linux/mfd/core.h b/include/linux/mfd/core.h
> index ad1b19a..ee4731b 100644
> --- a/include/linux/mfd/core.h
> +++ b/include/linux/mfd/core.h
> @@ -86,16 +86,20 @@ extern int mfd_clone_cell(const char *cell, const
> char **clones, */
> static inline const struct mfd_cell *mfd_get_cell(struct
> platform_device *pdev) {
> - return pdev->dev.platform_data;
> + return pdev->mfd_cell;
> }
>
> /*
> * Given a platform device that's been created by mfd_add_devices(),
> fetch
> * the .mfd_data entry from the mfd_cell that created it.
> + * Otherwise just return the platform_data pointer.

I'd also suggest describing why we fall back to
platform_data; to the casual reader, it would be confusing. Perhaps
something to the effect of, "This maintains compatibility with
platform drivers whose devices aren't created by the mfd layer, and
expect platform_data to contain what would've otherwise been in
mfd_data."

> */
> static inline void *mfd_get_data(struct platform_device *pdev)
> {
> - return mfd_get_cell(pdev)->mfd_data;
> + if (pdev->mfd_cell)
> + return mfd_get_cell(pdev)->mfd_data;
> + else
> + return pdev->dev.platform_data;

Not much point checking pdev->mfd_cell and then using an abstraction.
I'd just do "const struct mfd_cell *cell = mfd_get_cell(pdev); if
(cell) return cell->mfd_data;" or "if (pdev->mfd_cell) return
pdev->mfd_cell->mfd_data;"

> }
>
> extern int mfd_add_devices(struct device *parent, int id,
> diff --git a/include/linux/platform_device.h
> b/include/linux/platform_device.h index d96db98..744942c 100644
> --- a/include/linux/platform_device.h
> +++ b/include/linux/platform_device.h
> @@ -14,6 +14,8 @@
> #include <linux/device.h>
> #include <linux/mod_devicetable.h>
>
> +struct mfd_cell;
> +
> struct platform_device {
> const char * name;
> int id;
> @@ -23,6 +25,9 @@ struct platform_device {
>
> const struct platform_device_id *id_entry;
>
> + /* MFD cell pointer */
> + struct mfd_cell *mfd_cell;
> +
> /* arch specific additions */
> struct pdev_archdata archdata;
> };



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