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

Haylen Chu
2025-05-08T04:47:18Z

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@riscstar.com>
> ---
> 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.

...

> +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