linux-kernel - Re: [PATCH 1/2] of: base: Introduce of_alias_check

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Date:   Tue, 18 Sep 2018 13:57:16 +0200
From:   Michal Simek <michal.simek@...inx.com>
To:     Rob Herring <robh+dt@...nel.org>,
        Michal Simek <michal.simek@...inx.com>
CC:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Michal Simek <monstr@...str.eu>, <devicetree@...r.kernel.org>,
        Frank Rowand <frowand.list@...il.com>
Subject: Re: [PATCH 1/2] of: base: Introduce of_alias_check_id() to check
 alias IDs

On 13.9.2018 20:53, Rob Herring wrote:
> On Mon, Sep 3, 2018 at 8:14 AM Michal Simek <michal.simek@...inx.com> wrote:
>>
>> The function travers the lookup table to check if the request alias
>> id is compatible with the device driver match structure.
>> This function will be used by serial drivers to check if requested alias
>> is allocated or free to use.
>>
>> Signed-off-by: Michal Simek <michal.simek@...inx.com>
>> ---
>>
>> Based on discussion with Rob
>> https://lkml.org/lkml/2018/4/27/397
>> nbits is passed to the function not to limit only to 32/64bit fields.
>>
>> ---
>>  drivers/of/base.c  | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
>>  include/linux/of.h |  3 +++
>>  2 files changed, 51 insertions(+)
>>
>> diff --git a/drivers/of/base.c b/drivers/of/base.c
>> index 466e3c8582f0..236a85d69957 100644
>> --- a/drivers/of/base.c
>> +++ b/drivers/of/base.c
>> @@ -16,6 +16,7 @@
>>
>>  #define pr_fmt(fmt)    "OF: " fmt
>>
>> +#include <linux/bitmap.h>
>>  #include <linux/console.h>
>>  #include <linux/ctype.h>
>>  #include <linux/cpu.h>
>> @@ -1893,6 +1894,53 @@ int of_alias_get_id(struct device_node *np, const char *stem)
>>  EXPORT_SYMBOL_GPL(of_alias_get_id);
>>
>>  /**
>> + * of_alias_get_alias_list - Get alias list for the given device driver
>> + * @matches:   Array of OF device match structures to search in
>> + * @stem:      Alias stem of the given device_node
>> + * @bitmap:    Bitmap field pointer
>> + * @nbits:     Maximum number of alias ID which can be recorded it bitmap
>> + *
>> + * The function travels the lookup table to record alias ids for the given
>> + * device match structures and alias stem.
>> + */
>> +void of_alias_get_alias_list(const struct of_device_id *matches,
>> +                            const char *stem, unsigned long *bitmap,
>> +                            unsigned int nbits)
>> +{
>> +       struct alias_prop *app;
>> +
>> +       /* Zero bitmap field to make sure that all the time it is clean */
>> +       bitmap_zero(bitmap, nbits);
>> +
>> +       mutex_lock(&of_mutex);
>> +       pr_debug("%s: Looking for stem: %s\n", __func__, stem);
>> +       list_for_each_entry(app, &aliases_lookup, link) {
>> +               pr_debug("%s: stem: %s, id: %d\n",
>> +                        __func__, app->stem, app->id);
>> +
>> +               if (strcmp(app->stem, stem) != 0) {
>> +                       pr_debug("%s: stem comparison doesn't passed %s\n",
>> +                                __func__, app->stem);
>> +                       continue;
>> +               }
>> +
>> +               if (app->id >= nbits) {
>> +                       pr_debug("%s: ID %d greater then bitmap field %d\n",
>> +                               __func__, app->id, nbits);
>> +                       continue;
>> +               }
>> +
>> +               if (of_match_node(matches, app->np)) {
>> +                       pr_debug("%s: Allocated ID %d\n", __func__, app->id);
>> +                       set_bit(app->id, bitmap);
>> +               }
>> +               /* Alias exist but it not compatible with matches */
>> +       }
>> +       mutex_unlock(&of_mutex);
>> +}
>> +EXPORT_SYMBOL_GPL(of_alias_get_alias_list);
>> +
>> +/**
>>   * of_alias_get_highest_id - Get highest alias id for the given stem
>>   * @stem:      Alias stem to be examined
>>   *
>> diff --git a/include/linux/of.h b/include/linux/of.h
>> index 4d25e4f952d9..e474710e3930 100644
>> --- a/include/linux/of.h
>> +++ b/include/linux/of.h
>> @@ -387,6 +387,9 @@ extern int of_phandle_iterator_args(struct of_phandle_iterator *it,
>>  extern void of_alias_scan(void * (*dt_alloc)(u64 size, u64 align));
>>  extern int of_alias_get_id(struct device_node *np, const char *stem);
>>  extern int of_alias_get_highest_id(const char *stem);
>> +extern void of_alias_get_alias_list(const struct of_device_id *matches,
>> +                                   const char *stem, unsigned long *bitmap,
>> +                                   unsigned int nbits);
> 
> You should go ahead and add an empty function too as the other 2 alias
> functions have one.

ok. I have added that function. Also I realized that this function
should return return value to let users know if this function is not
returning proper values. I have updated this in v2.

> 
> With that, I'm assuming this is going with your serial patches:

yes that will be the best because serial driver is only one user.

> 
> Reviewed-by: Rob Herring <robh@...nel.org>

Added to v2. If you don't agree with also adding return value please let
me know.

Thanks,
Michal