[PATCH v2 03/17] drivers: reset: Handle gracefully NULL pointers

[Simon Glass]

Hi Kishon,

On Mon, 5 Apr 2021 at 11:28, Kishon Vijay Abraham I <kishon at ti.com> wrote:
>
> From: Jean-Jacques Hiblot <jjhiblot at ti.com>
>
> The reset framework provides devm_reset_control_get_optional()
> which can return NULL (not an error case). So all the other reset_ops
> should handle NULL gracefully. Prepare the way for a managed reset
> API by handling NULL pointers without crashing nor failing.
>
> Signed-off-by: Jean-Jacques Hiblot <jjhiblot at ti.com>
> Signed-off-by: Vignesh Raghavendra <vigneshr at ti.com>
> Signed-off-by: Kishon Vijay Abraham I <kishon at ti.com>
> ---
>  drivers/reset/reset-uclass.c | 30 +++++++++++++++++-------------
>  1 file changed, 17 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/reset/reset-uclass.c b/drivers/reset/reset-uclass.c
> index 071c389ca0..98304bc0ee 100644
> --- a/drivers/reset/reset-uclass.c
> +++ b/drivers/reset/reset-uclass.c
> @@ -13,9 +13,12 @@
>  #include <dm/devres.h>
>  #include <dm/lists.h>
>
> -static inline struct reset_ops *reset_dev_ops(struct udevice *dev)
> +struct reset_ops nop_reset_ops = {
> +};
> +
> +static inline struct reset_ops *reset_dev_ops(struct reset_ctl *r)
>  {
> -       return (struct reset_ops *)dev->driver->ops;
> +       return r ? (struct reset_ops *)r->dev->driver->ops : &nop_reset_ops;

This behaviour still seems odd to me. Why do you have a reset driver
with no ops? That is not allowed.

>  }
>
>  static int reset_of_xlate_default(struct reset_ctl *reset_ctl,
> @@ -54,9 +57,10 @@ static int reset_get_by_index_tail(int ret, ofnode node,
>                 debug("%s %d\n", ofnode_get_name(args->node), args->args[0]);
>                 return ret;
>         }
> -       ops = reset_dev_ops(dev_reset);
>
>         reset_ctl->dev = dev_reset;
> +       ops = reset_dev_ops(reset_ctl);
> +
>         if (ops->of_xlate)
>                 ret = ops->of_xlate(reset_ctl, args);
>         else
> @@ -162,29 +166,29 @@ int reset_get_by_name(struct udevice *dev, const char *name,
>
>  int reset_request(struct reset_ctl *reset_ctl)
>  {
> -       struct reset_ops *ops = reset_dev_ops(reset_ctl->dev);
> +       struct reset_ops *ops = reset_dev_ops(reset_ctl);
>
>         debug("%s(reset_ctl=%p)\n", __func__, reset_ctl);
>
> -       return ops->request(reset_ctl);
> +       return ops->request ? ops->request(reset_ctl) : 0;

Can you check this first and return -ENOSYS ? E.g.

if (!ops->request)
   return -ENOSYS;

return ops->request(reset_ctl);

Same below

>  }
>
>  int reset_free(struct reset_ctl *reset_ctl)
>  {
> -       struct reset_ops *ops = reset_dev_ops(reset_ctl->dev);
> +       struct reset_ops *ops = reset_dev_ops(reset_ctl);
>
>         debug("%s(reset_ctl=%p)\n", __func__, reset_ctl);
>
> -       return ops->rfree(reset_ctl);
> +       return ops->rfree ? ops->rfree(reset_ctl) : 0;
>  }
>
>  int reset_assert(struct reset_ctl *reset_ctl)
>  {
> -       struct reset_ops *ops = reset_dev_ops(reset_ctl->dev);
> +       struct reset_ops *ops = reset_dev_ops(reset_ctl);
>
>         debug("%s(reset_ctl=%p)\n", __func__, reset_ctl);
>
> -       return ops->rst_assert(reset_ctl);
> +       return ops->rst_assert ? ops->rst_assert(reset_ctl) : 0;
>  }
>
>  int reset_assert_bulk(struct reset_ctl_bulk *bulk)
> @@ -202,11 +206,11 @@ int reset_assert_bulk(struct reset_ctl_bulk *bulk)
>
>  int reset_deassert(struct reset_ctl *reset_ctl)
>  {
> -       struct reset_ops *ops = reset_dev_ops(reset_ctl->dev);
> +       struct reset_ops *ops = reset_dev_ops(reset_ctl);
>
>         debug("%s(reset_ctl=%p)\n", __func__, reset_ctl);
>
> -       return ops->rst_deassert(reset_ctl);
> +       return ops->rst_deassert ? ops->rst_deassert(reset_ctl) : 0;
>  }
>
>  int reset_deassert_bulk(struct reset_ctl_bulk *bulk)
> @@ -224,11 +228,11 @@ int reset_deassert_bulk(struct reset_ctl_bulk *bulk)
>
>  int reset_status(struct reset_ctl *reset_ctl)
>  {
> -       struct reset_ops *ops = reset_dev_ops(reset_ctl->dev);
> +       struct reset_ops *ops = reset_dev_ops(reset_ctl);
>
>         debug("%s(reset_ctl=%p)\n", __func__, reset_ctl);
>
> -       return ops->rst_status(reset_ctl);
> +       return ops->rst_status ? ops->rst_status(reset_ctl) : 0;
>  }
>
>  int reset_release_all(struct reset_ctl *reset_ctl, int count)
> --
> 2.17.1
>

Regards,
Simon