Hi Michal,
On Fri, 18 Jan 2019 at 08:13, Michal Simek <michal.si...@xilinx.com> wrote:
>
> The same functionality was added to Linux for i2c bus registration with this
> commit message:
>
> "
> of: base: add function to get highest id of an alias stem
>
> I2C supports adding adapters using either a dynamic or fixed id. The
> latter is provided by aliases in the DT case. To prevent id collisions
> of those two types, install this function which gives us the highest
> fixed id, so we can then let the dynamically created ones come after
> this highest number.
>
> Signed-off-by: Wolfram Sang <wsa+rene...@sang-engineering.com>
> Acked-by: Rob Herring <r...@kernel.org>
> Signed-off-by: Wolfram Sang <w...@the-dreams.de>
> "
>
> Add it also to U-Boot for DM I2C support.
>
> Signed-off-by: Michal Simek <michal.si...@xilinx.com>
> ---
>
> drivers/core/of_access.c | 18 ++++++++++++++++++
> include/dm/of_access.h | 9 +++++++++
> 2 files changed, 27 insertions(+)
>
> diff --git a/drivers/core/of_access.c b/drivers/core/of_access.c
> index 14c020a687b7..7c2df2354109 100644
> --- a/drivers/core/of_access.c
> +++ b/drivers/core/of_access.c
> @@ -812,6 +812,24 @@ int of_alias_get_id(const struct device_node *np, const
> char *stem)
> return id;
> }
>
> +int of_alias_get_highest_id(const char *stem)
> +{
> + struct alias_prop *app;
> + int id = -ENODEV;
> +
> + mutex_lock(&of_mutex);
> + list_for_each_entry(app, &aliases_lookup, link) {
> + if (strcmp(app->stem, stem) != 0)
> + continue;
> +
> + if (app->id > id)
> + id = app->id;
> + }
> + mutex_unlock(&of_mutex);
> +
> + return id;
> +}
> +
> struct device_node *of_get_stdout(void)
> {
> return of_stdout;
> diff --git a/include/dm/of_access.h b/include/dm/of_access.h
> index 5ed1a0cdb427..5cbfd220bfd4 100644
> --- a/include/dm/of_access.h
> +++ b/include/dm/of_access.h
> @@ -425,6 +425,15 @@ int of_alias_scan(void);
> int of_alias_get_id(const struct device_node *np, const char *stem);
>
> /**
> + * of_alias_get_highest_id - Get highest alias id for the given stem
> + * @stem: Alias stem to be examined
> + *
> + * The function travels the lookup table to get the highest alias id for the
> + * given alias stem. It returns the alias id if found.
@return
> + */
> +int of_alias_get_highest_id(const char *stem);
> +
> +/**
> * of_get_stdout() - Get node to use for stdout
> *
> * @return node referred to by stdout-path alias, or NULL if none
> --
> 1.9.1
>
Can we place have a test that calls this for a few values?
Also see uclass_find_next_free_req_seq() and uclass_resolve_seq()
which is what U-Boot does today. It is first in, first served. This is
supposed to mean that devices without an alias don't get a req_seq
value, meaning that the seq value is set to the next available value.
I suspect it is OK to change the behaviour though. It might affect
some boards which rely on not having aliases but still getting bus
numbers.
Regards,
Simon
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