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

Alex Elder
2025-05-08T20:04:49Z

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@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.

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