[U-Boot] [PATCH 1/4] dm: core: Add of_alias_get_highest_id()

[Michal Simek]

On 31. 01. 19 11:04, Simon Glass wrote:
> Hi Michal,
> 
> On Fri, 18 Jan 2019 at 08:13, Michal Simek <michal.simek at 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+renesas at sang-engineering.com>
>> Acked-by: Rob Herring <robh at kernel.org>
>> Signed-off-by: Wolfram Sang <wsa at the-dreams.de>
>> "
>>
>> Add it also to U-Boot for DM I2C support.
>>
>> Signed-off-by: Michal Simek <michal.simek at 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.
> 

Let me play with it and see that calling sequence.


> 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.

Do you mean with I2C? Or different buses?

I don't think there is any affected board with DM_I2C and OF_CONTROL
because unlisted aliases are using req_seq -1 now.

Thanks,
Michal