Subject: [PATCHv9 06/43] CLK: ti: add init support for clock IP blocks

From: [email-masked] (Nishanth Menon)
Date: Fri, 1 Nov 2013 14:13:55 -0500

On 11/01/2013 04:12 AM, Tero Kristo wrote:
> On 10/31/2013 05:42 PM, Nishanth Menon wrote:
>> On 10/25/2013 10:57 AM, Tero Kristo wrote:
>>> ti_dt_clk_init_provider() can now be used to initialize the contents of
>>> a single clock IP block. This parses all the clocks under the IP block
>>> and calls the corresponding init function for them.
>>>
>>> Signed-off-by: Tero Kristo <[email-masked]>
>>> ---
>>>   drivers/clk/ti/clk.c   |   59 ++++++++++++++++++++++++++++++++++++++++++++++++
>>>   include/linux/clk/ti.h |    1 +
>>>   2 files changed, 60 insertions(+)
>>>
>>> diff --git a/drivers/clk/ti/clk.c b/drivers/clk/ti/clk.c
>>> index ad58b01..7f030d7 100644
>>> --- a/drivers/clk/ti/clk.c
>>> +++ b/drivers/clk/ti/clk.c
>>> @@ -19,6 +19,9 @@
>>>   #include <linux/clkdev.h>
>>>   #include <linux/clk/ti.h>
>>>   #include <linux/of.h>
>>> +#include <linux/list.h>
>>> +
>>> +extern struct of_device_id __clk_of_table[];
>>>
>>>   /**
>>>    * ti_dt_clocks_register - register DT duplicate clocks during boot
>>> @@ -50,3 +53,59 @@ void __init ti_dt_clocks_register(struct ti_dt_clk oclks[])
>>>   		}
>>>   	}
>>>   }
>>> +
>>> +typedef int (*ti_of_clk_init_cb_t)(struct device_node *, struct regmap *);
>>> +
>>> +struct clk_init_item {
>>> +	struct regmap *regmap;
>>> +	struct device_node *np;
>>> +	ti_of_clk_init_cb_t init_cb;
>>> +	struct list_head node;
>>> +};
>>> +
>>> +static LIST_HEAD(retry_list);
>>> +
>>> +void __init ti_dt_clk_init_provider(struct device_node *parent,
>>> +				    struct regmap *regmap)
>>> +{
>>> +	const struct of_device_id *match;
>>> +	struct device_node *np;
>>> +	ti_of_clk_init_cb_t clk_init_cb;
>>> +	struct clk_init_item *retry;
>>> +	struct clk_init_item *tmp;
>>> +	int ret;
>>> +
>>> +	for_each_child_of_node(parent, np) {
>>> +		match = of_match_node(__clk_of_table, np);
>>> +		if (!match)
>>> +			continue;
>>> +		clk_init_cb = match->data;
>>
>> I must admit I am confused here.
> 
> Yea this patch is something I am not quite comfortable myself yet and 
> would like improvement ideas....
> 
>> a) of_clk_init (in the generic clk.c) uses of_clk_init_cb_t as match
>> data. The prototype of the generic of_clk_init_cb_t is typedef void
>> (*of_clk_init_cb_t)(struct device_node *);
>> b) both of_clk_init and ti_dt_clk_init_provider looks up clock nodes
>> from __clk_of_table
> 
> __clk_of_table contains the function pointers for the clock init 
> functions, not clock nodes.

yes, apologies, should have stated the prototypes of functions in a
single __clk_of_table should not be two different argument list. The
reason is as follows: CLK_OF_DECLARE fills up that list. there can be
generic drivers such as [1] which might be registered, OR in the case
of MULTI_ARCH - multiple other SoC drivers would have registered
there. There is a bunch of stuff we could mess up here.

If we do not have a choice, if we would like to maintain a different
prototype based init list, we should probably do it in a different
structure - example __clk_of_table_regmap or something similar..

> 
>>
>> I assume we need ti_dt_clk_init_provider to be always called with
>> clock list, as a result of_clk_init(NULL); will never be invoked. This
>> is counter productive as you have have generic non SoC clock providers
>> as well who would have been invoked with of_clk_init(NULL);
> 
> Can't call of_clk_init(NULL) anymore, as Paul wants to map the clock 
> nodes under respective IP blocks. Two reasons here:
> 
> a) This requires me to pass some info from the IP block (CM1/CM2/PRM) to 
> the clock init functions, basically the pointer to the memory map region 
> (regmap.)
> b) of_clk_init(NULL) will initialize all the clock nodes in the system, 
> irrespective of the hierarchy considerations.
> 
> Only thing that can be done, is to make the API introduced in this patch 
> a generic API and call it something like of_clk_init_children().

you still can do that:

of_prcm_init->ti_dt_clk_init_provider-> instead of matching nodes from
__clk_of_table, you can make it __clk_of_regmap_table -> the
CLK_OF_DECLARE will not be good enough here ofcourse, but this will
probably belong to a generic regmap enabled clock support framework -
i dont see much that is TI specific in drivers/clk/ti/clk.c and it
makes sense to be part of generic clock framework handling as generic
clock framework will receive regmap support based on previous patches.
that allows for other platforms to use regmap based clk drivers as well.

[1] http://marc.info/?l=linux-omap&m=138331451210184&w=2
-- 
Regards,
Nishanth Menon