Re: [PATCH v6 3/6] clk: spacemit: set up reset auxiliary devices

[Alex Elder]

On 5/7/25 11:46 PM, Haylen Chu wrote:
> On Tue, May 06, 2025 at 04:06:34PM -0500, Alex Elder wrote:
> > Add a new reset_name field to the spacemit_ccu_data structure.  If it is
> > non-null, the CCU implements a reset controller, and the name will be
> > used as the name for the auxiliary device that implements it.
> >
> > Define a new type to hold an auxiliary device as well as the regmap
> > pointer that will be needed by CCU reset controllers.  Set up code to
> > initialize and add an auxiliary device for any CCU that implements reset
> > functionality.
> >
> > Make it optional for a CCU to implement a clock controller.  This
> > doesn't apply to any of the existing CCUs but will for some new ones
> > that will be added soon.
> >
> > Signed-off-by: Alex Elder <elder@xxxxxxxxxxxx>
> > ---
> >   drivers/clk/spacemit/ccu-k1.c | 85 +++++++++++++++++++++++++++++++----
> >   include/soc/spacemit/ccu_k1.h | 12 +++++
> >   2 files changed, 89 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/clk/spacemit/ccu-k1.c b/drivers/clk/spacemit/ccu-k1.c
> > index 9545cfe60b92b..6b1845e899e5f 100644
> > --- a/drivers/clk/spacemit/ccu-k1.c
> > +++ b/drivers/clk/spacemit/ccu-k1.c
>
> ...
>
> > +static void spacemit_cadev_release(struct device *dev)
> > +{
> > +	struct auxiliary_device *adev = to_auxiliary_dev(dev);
> > +
> > +	kfree(to_spacemit_ccu_adev(adev));
> > +}
>
> spacemit_ccu_adev structures are allocated with devm_kzalloc() in
> spacemit_ccu_reset_register(), which means its lifetime is bound to the
> driver and it'll be automatically released after driver removal; won't
> there be a possibility of double-free? I think the release callback
> could be simply dropped.

You are correct.  And unfortunately I didn't include the fix
for this in the patches I just posted, because somehow this
message was not included with the group in my mail program.

I'm going to send v8 after I fix this and verify it again.

					-Alex


> ...
>
> > +static int spacemit_ccu_reset_register(struct device *dev,
> > +				       struct regmap *regmap,
> > +				       const char *reset_name)
> > +{
> > +	struct spacemit_ccu_adev *cadev;
> > +	struct auxiliary_device *adev;
> > +	static u32 next_id;
> > +	int ret;
> > +
> > +	/* Nothing to do if the CCU does not implement a reset controller */
> > +	if (!reset_name)
> > +		return 0;
> > +
> > +	cadev = devm_kzalloc(dev, sizeof(*cadev), GFP_KERNEL);
>
> Here spacemit_ccu_adev is allocated.
>
> > +	if (!cadev)
> > +		return -ENOMEM;
> > +	cadev->regmap = regmap;
> > +
> > +	adev = &cadev->adev;
> > +	adev->name = reset_name;
> > +	adev->dev.parent = dev;
> > +	adev->dev.release = spacemit_cadev_release;
> > +	adev->dev.of_node = dev->of_node;
> > +	adev->id = next_id++;
> > +
> > +	ret = auxiliary_device_init(adev);
> > +	if (ret)
> > +		return ret;
> > +
> > +	ret = auxiliary_device_add(adev);
> > +	if (ret) {
> > +		auxiliary_device_uninit(adev);
> > +		return ret;
> > +	}
> > +
> > +	return devm_add_action_or_reset(dev, spacemit_adev_unregister, adev);
> > +}
> > +
>
> Best regards,
> Haylen Chu