Subject: [PATCHv5 11/35] ARM: OMAP2+: clock: move clock provider infrastructure to clock driver

From: [email-masked] (Tero Kristo)
Date: Thu, 26 Mar 2015 20:49:56 +0200

On 03/26/2015 07:30 PM, Tony Lindgren wrote:
> * Tero Kristo <[email-masked]> [150326 03:55]:
>> On 03/26/2015 09:24 AM, Tero Kristo wrote:
>>> On 03/26/2015 01:17 AM, Tony Lindgren wrote:
>>>> * Tero Kristo <[email-masked]> [150325 08:12]:
>>>>>
>>>>> Splits the clock provider init out of the PRM driver and moves it to
>>>>> clock driver. This is needed so that once the PRCM drivers are
>>>>> separated,
>>>>> they can logically just access the clock driver not needing to go
>>>>> through
>>>>> common PRM code. This would be wrong in the case of control module for
>>>>> example.
>>>> ...
>>>>
>>>>> --- a/arch/arm/mach-omap2/clock.c
>>>>> +++ b/arch/arm/mach-omap2/clock.c
>>>> ...
>>>>> -u32 omap2_clk_readl(struct clk_hw_omap *clk, void __iomem *reg)
>>>>> +u32 omap2_clk_memmap_readl(void __iomem *reg)
>>>>>   {
>>>>> -    u32 val;
>>>>> +    struct clk_omap_reg *r = (struct clk_omap_reg *)&reg;
>>>>>
>>>>> -    if (clk->flags & MEMMAP_ADDRESSING) {
>>>>> -        struct clk_omap_reg *r = (struct clk_omap_reg *)&reg;
>>>>> -        val = readl_relaxed(clk_memmaps[r->index] + r->offset);
>>>>> -    } else {
>>>>> -        val = readl_relaxed(reg);
>>>>> -    }
>>>>> +    return readl_relaxed(clk_memmaps[r->index] + r->offset);
>>>>> +}
>>>>
>>>> The cast from void __iomem *reg to struct clk_omap_reg *r looks still
>>>> nasty.. Why don't you add the IO address into struct clk_omap_reg:
>>>>
>>>> struct clk_omap_reg {
>>>>     u16 offset;
>>>>     u16 index;
>>>>     struct regmap *regmap;
>>>>     void __iomem *addr;
>>>> };
>>>> ...
>>>>
>>>> Then populate it during init and then have the clock code use it
>>>> directly if available? Then it seems you would not need the
>>>> static struct clk_iomap *clk_memmaps[CLK_MAX_MEMMAPS] at all?
>>>
>>> Doing a change like this should probably be planned, but it is a larger
>>> modification. Currently none of the low-level clock APIs support this,
>>> but instead expect a direct iomem pointer against which they can do
>>> arithmetic operations. The major problem is the companion clocks, which
>>> just XOR some bits in the registers to get ICLK / IDLEST register offset
>> >from FCLK.
>>>
>>> So, for now, clock code just uses the void __iomem pointer as a storage
>>> class for struct clk_omap_reg, on which arithmetic operations can be done.
>
> Well how about keep the check if (clk->flags & MEMMAP_ADDRESSING) at
> least? Maybe WARN_ON(!(clk->flags & MEMMAP_ADDRESSING))?
>
> Otherwise this could be a nightmare to debug if anything goes wrong.

Yea, adding a warning is a good idea for now, I'll do this update 
tomorrow morning.

-Tero

>
>> I did this change as a trial, and this is the diff required to get it
>> working:
>>
>>   arch/arm/mach-omap2/clkt_iclk.c |   20 ++++++++---------
>>   arch/arm/mach-omap2/clock.c     |   47
>> +++++++++++++++++----------------------
>>   arch/arm/mach-omap2/clock.h     |    8 +++----
>>   arch/arm/mach-omap2/clock2430.c |    5 +++--
>>   arch/arm/mach-omap2/clock34xx.c |   36 ++++++++++++++----------------
>>   arch/arm/mach-omap2/clock3517.c |   20 ++++++++---------
>>   arch/arm/mach-omap2/cm.h        |    4 +++-
>>   arch/arm/mach-omap2/cm2xxx.c    |    9 +++-----
>>   arch/arm/mach-omap2/cm3xxx.c    |   10 +++------
>>   drivers/clk/ti/clk.c            |   10 +++++----
>>   drivers/clk/ti/divider.c        |   24 ++++++++++++++------
>>   drivers/clk/ti/dpll.c           |   11 ++++-----
>>   drivers/clk/ti/gate.c           |   21 +++++++++++------
>>   drivers/clk/ti/interface.c      |    9 ++++----
>>   drivers/clk/ti/mux.c            |   22 ++++++++++++------
>>   include/linux/clk/ti.h          |    5 +++--
>>   16 files changed, 137 insertions(+), 124 deletions(-)
>>
>> I think we should probably keep this out of this set now and do this while
>> moving the OMAP core clock support code under clock driver... just to keep
>> it more easily manageable.
>
> OK fine with me to do that as a follow-up patch.
>
> Regards,
>
> Tony
>