Subject: [PATCH] of: Add missing node iteration stubs for disabled CONFIG_OF

From: [email-masked] (Jonathan Austin)
Date: Wed, 12 Jun 2013 11:10:49 +0100

On 11/06/13 22:51, Grant Likely wrote:
> On Tue, 11 Jun 2013 17:22:55 +0100, Jonathan Austin <[email-masked]> wrote:
>> Hi Rob, Thomasz,
>>
>> (dredging up an oldish thread as I just ran in to this issue)
>>
>> On 01/04/13 22:19, Rob Herring wrote:
>>> On 03/09/2013 02:15 PM, Tomasz Figa wrote:
>>>> This patch moves several for_each macros out of the #ifdef CONFIG_OF
>>>> block and adds inline stubs for functions used by these macros, compiled
>>>> conditionally when CONFIG_OF is not enabled.
>>>>
>>>> This eliminates the need to explicitly check for CONFIG_OF in driver
>>>> code using mentioned functions and macros.
>>>
>>> Do you have some users of this?
>>
>> I do!
>>
>> Or at least I might.
>>
>> I'm not certain as perhaps the fix to what I describe below is to add
>> dependencies on CONFIG_OF - it isn't clear to me either way:
>>
>> With both psci and arch_timers (CONFIG_ARM_PSCI, CONFIG_ARM_ARCH_TIMER)
>> and without CONFIG_OF we get a build failure because we lack the definition
>> of of_find_matching_node():
>>
>> eg:
>> arch/arm/kernel/psci.c:167:2: error: implicit declaration of function ???of_find_matching_node??? [-Werror=implicit-function-declaration]
>>
>> The same happens with arm_arch_timer.c (well, there's a patch required to
>> include linux/of.h first, after which Thomasz's patch is relevant).
>
> That code path is completely broken if CONFIG_OF is not set. psci_init()
> is nothing but calls to CONFIG_OF infrastructure! I think that code

Well, it looks like the intention of that code was to just behave like 
there was no relevant node in the case the CONFIG_OF was disabled:

	np = of_find_matching_node(NULL, psci_of_match);
	if (!np)
		return 0;

If of_find_matching() node behaved like of_match_node() then nothing 
would be 'broken' per se, but we would have a bunch of useless code 
compiled in to our kernel.

> needs to depend on CONFIG_OF, or at least be wrapped with
> "if (IS_ENABLED(CONFIG_OF))" if there are still usable parts when
> CONFIG_OF is disabled. Frankly I don't see that as being a real concern.

Indeed, despite the clarification above, I think it'd be fine to not 
build these without CONFIG_OF.

I'm happy to submit a patches to add dependencies on CONFIG_OF for 
ARM_ARCH_TIMER and ARM_PSCI - I don't think either of those will get any 
complaints because as you say, neither makes very much sense without a 
DT to specify them.

Thanks,
Jonny

>
> That said, Arnd has posted a patch that moves at least some of the function
> prototypes out from under the #ifdef block so that GCC can do syntax
> checking on disabled code. That overlaps a bit with this patch.
>
> Regardless, I'm not going to apply it without a legitimate (as opposed
> to theoretical) user.
>
> g.
>
>> So, I guess the question is whether we should expect PSCI and ARM_ARCH_TIMER
>> to depend on CONFIG_OF, or whether we'd like them to fail gracefully in the
>> case that we *don't* have CONFIG_OF. I think the current situation is broken
>> either way...
>>
>> Thoughts?
>>
>> Jonny
>>
>>>
>>> Rob
>>>
>>>>
>>>> Signed-off-by: Tomasz Figa <[email-masked]>
>>>> ---
>>>>    include/linux/of.h | 92 +++++++++++++++++++++++++++++++++++++-----------------
>>>>    1 file changed, 63 insertions(+), 29 deletions(-)
>>>>
>>>> diff --git a/include/linux/of.h b/include/linux/of.h
>>>> index a0f1292..7a736b8 100644
>>>> --- a/include/linux/of.h
>>>> +++ b/include/linux/of.h
>>>> @@ -86,6 +86,31 @@ static inline struct device_node *of_node_get(struct device_node *node)
>>>>    static inline void of_node_put(struct device_node *node) { }
>>>>    #endif /* !CONFIG_OF_DYNAMIC */
>>>>
>>>> +#define for_each_node_by_name(dn, name) \
>>>> +     for (dn = of_find_node_by_name(NULL, name); dn; \
>>>> +          dn = of_find_node_by_name(dn, name))
>>>> +#define for_each_node_by_type(dn, type) \
>>>> +     for (dn = of_find_node_by_type(NULL, type); dn; \
>>>> +          dn = of_find_node_by_type(dn, type))
>>>> +#define for_each_compatible_node(dn, type, compatible) \
>>>> +     for (dn = of_find_compatible_node(NULL, type, compatible); dn; \
>>>> +          dn = of_find_compatible_node(dn, type, compatible))
>>>> +#define for_each_matching_node(dn, matches) \
>>>> +     for (dn = of_find_matching_node(NULL, matches); dn; \
>>>> +          dn = of_find_matching_node(dn, matches))
>>>> +#define for_each_matching_node_and_match(dn, matches, match) \
>>>> +     for (dn = of_find_matching_node_and_match(NULL, matches, match); \
>>>> +          dn; dn = of_find_matching_node_and_match(dn, matches, match))
>>>> +#define for_each_child_of_node(parent, child) \
>>>> +     for (child = of_get_next_child(parent, NULL); child != NULL; \
>>>> +          child = of_get_next_child(parent, child))
>>>> +#define for_each_available_child_of_node(parent, child) \
>>>> +     for (child = of_get_next_available_child(parent, NULL); child != NULL; \
>>>> +          child = of_get_next_available_child(parent, child))
>>>> +#define for_each_node_with_property(dn, prop_name) \
>>>> +     for (dn = of_find_node_with_property(NULL, prop_name); dn; \
>>>> +          dn = of_find_node_with_property(dn, prop_name))
>>>> +
>>>>    #ifdef CONFIG_OF
>>>>
>>>>    /* Pointer for first entry in chain of all nodes. */
>>>> @@ -167,19 +192,10 @@ static inline const char *of_node_full_name(const struct device_node *np)
>>>>
>>>>    extern struct device_node *of_find_node_by_name(struct device_node *from,
>>>>         const char *name);
>>>> -#define for_each_node_by_name(dn, name) \
>>>> -     for (dn = of_find_node_by_name(NULL, name); dn; \
>>>> -          dn = of_find_node_by_name(dn, name))
>>>>    extern struct device_node *of_find_node_by_type(struct device_node *from,
>>>>         const char *type);
>>>> -#define for_each_node_by_type(dn, type) \
>>>> -     for (dn = of_find_node_by_type(NULL, type); dn; \
>>>> -          dn = of_find_node_by_type(dn, type))
>>>>    extern struct device_node *of_find_compatible_node(struct device_node *from,
>>>>         const char *type, const char *compat);
>>>> -#define for_each_compatible_node(dn, type, compatible) \
>>>> -     for (dn = of_find_compatible_node(NULL, type, compatible); dn; \
>>>> -          dn = of_find_compatible_node(dn, type, compatible))
>>>>    extern struct device_node *of_find_matching_node_and_match(
>>>>         struct device_node *from,
>>>>         const struct of_device_id *matches,
>>>> @@ -190,12 +206,6 @@ static inline struct device_node *of_find_matching_node(
>>>>    {
>>>>         return of_find_matching_node_and_match(from, matches, NULL);
>>>>    }
>>>> -#define for_each_matching_node(dn, matches) \
>>>> -     for (dn = of_find_matching_node(NULL, matches); dn; \
>>>> -          dn = of_find_matching_node(dn, matches))
>>>> -#define for_each_matching_node_and_match(dn, matches, match) \
>>>> -     for (dn = of_find_matching_node_and_match(NULL, matches, match); \
>>>> -          dn; dn = of_find_matching_node_and_match(dn, matches, match))
>>>>    extern struct device_node *of_find_node_by_path(const char *path);
>>>>    extern struct device_node *of_find_node_by_phandle(phandle handle);
>>>>    extern struct device_node *of_get_parent(const struct device_node *node);
>>>> @@ -207,14 +217,6 @@ extern struct device_node *of_get_next_available_child(
>>>>
>>>>    extern struct device_node *of_get_child_by_name(const struct device_node *node,
>>>>                                         const char *name);
>>>> -#define for_each_child_of_node(parent, child) \
>>>> -     for (child = of_get_next_child(parent, NULL); child != NULL; \
>>>> -          child = of_get_next_child(parent, child))
>>>> -
>>>> -#define for_each_available_child_of_node(parent, child) \
>>>> -     for (child = of_get_next_available_child(parent, NULL); child != NULL; \
>>>> -          child = of_get_next_available_child(parent, child))
>>>> -
>>>>    static inline int of_get_child_count(const struct device_node *np)
>>>>    {
>>>>         struct device_node *child;
>>>> @@ -228,10 +230,6 @@ static inline int of_get_child_count(const struct device_node *np)
>>>>
>>>>    extern struct device_node *of_find_node_with_property(
>>>>         struct device_node *from, const char *prop_name);
>>>> -#define for_each_node_with_property(dn, prop_name) \
>>>> -     for (dn = of_find_node_with_property(NULL, prop_name); dn; \
>>>> -          dn = of_find_node_with_property(dn, prop_name))
>>>> -
>>>>    extern struct property *of_find_property(const struct device_node *np,
>>>>                                          const char *name,
>>>>                                          int *lenp);
>>>> @@ -353,13 +351,28 @@ static inline struct device_node *of_find_node_by_name(struct device_node *from,
>>>>         return NULL;
>>>>    }
>>>>
>>>> +static inline struct device_node *of_find_node_by_type(struct device_node *from,
>>>> +     const char *type)
>>>> +{
>>>> +     return NULL;
>>>> +}
>>>> +
>>>>    static inline bool of_have_populated_dt(void)
>>>>    {
>>>>         return false;
>>>>    }
>>>>
>>>> -#define for_each_child_of_node(parent, child) \
>>>> -     while (0)
>>>> +static inline struct device_node *of_get_next_child(const struct device_node *node,
>>>> +                                          struct device_node *prev)
>>>> +{
>>>> +     return NULL;
>>>> +}
>>>> +
>>>> +static inline struct device_node *of_get_next_available_child(
>>>> +     const struct device_node *node, struct device_node *prev)
>>>> +{
>>>> +     return NULL;
>>>> +}
>>>>
>>>>    static inline struct device_node *of_get_child_by_name(
>>>>                                         const struct device_node *node,
>>>> @@ -373,6 +386,12 @@ static inline int of_get_child_count(const struct device_node *np)
>>>>         return 0;
>>>>    }
>>>>
>>>> +static inline struct device_node *of_find_node_with_property(
>>>> +     struct device_node *from, const char *prop_name)
>>>> +{
>>>> +     return NULL;
>>>> +}
>>>> +
>>>>    static inline int of_device_is_compatible(const struct device_node *device,
>>>>                                           const char *name)
>>>>    {
>>>> @@ -394,6 +413,21 @@ static inline struct device_node *of_find_compatible_node(
>>>>         return NULL;
>>>>    }
>>>>
>>>> +static inline struct device_node *of_find_matching_node_and_match(
>>>> +     struct device_node *from,
>>>> +     const struct of_device_id *matches,
>>>> +     const struct of_device_id **match)
>>>> +{
>>>> +     return NULL;
>>>> +}
>>>> +
>>>> +static inline struct device_node *of_find_matching_node(
>>>> +     struct device_node *from,
>>>> +     const struct of_device_id *matches)
>>>> +{
>>>> +     return NULL;
>>>> +}
>>>> +
>>>>    static inline int of_property_read_u8_array(const struct device_node *np,
>>>>                         const char *propname, u8 *out_values, size_t sz)
>>>>    {
>>>>
>>>
>>>
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>>>
>>
>>
>>
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>