On 05/23/2014 07:33 PM, Mike Turquette wrote:
> Quoting Alex Elder (2014-05-20 05:52:38)
>> Add a flag that tracks whether a clock has already been initialized.
>> This will be used by the next patch to avoid initializing a clock
>> more than once when it's listed as a prerequisite.
>>
>> Signed-off-by: Alex Elder <elder@xxxxxxxxxx>
>> ---
>> drivers/clk/bcm/clk-kona.c | 17 +++++++++++++++--
>> drivers/clk/bcm/clk-kona.h | 7 +++++++
>> 2 files changed, 22 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/clk/bcm/clk-kona.c b/drivers/clk/bcm/clk-kona.c
>> index d603c4e..d8a7f38 100644
>> --- a/drivers/clk/bcm/clk-kona.c
>> +++ b/drivers/clk/bcm/clk-kona.c
>> @@ -27,6 +27,9 @@
>> #define CCU_ACCESS_PASSWORD 0xA5A500
>> #define CLK_GATE_DELAY_LOOP 2000
>>
>> +#define clk_is_initialized(_clk) FLAG_TEST((_clk), KONA, INITIALIZED)
>> +#define clk_set_initialized(_clk) FLAG_SET((_clk), KONA, INITIALIZED)
>> +
>> /* Bitfield operations */
>>
>> /* Produces a mask of set bits covering a range of a 32-bit value */
>> @@ -1194,13 +1197,23 @@ static bool __peri_clk_init(struct kona_clk *bcm_clk)
>>
>> static bool __kona_clk_init(struct kona_clk *bcm_clk)
>> {
>> + bool ret;
>> +
>> + if (clk_is_initialized(bcm_clk))
>> + return true;
>> +
>> switch (bcm_clk->type) {
>> case bcm_clk_peri:
>> - return __peri_clk_init(bcm_clk);
>> + ret = __peri_clk_init(bcm_clk);
>
> Hi Alex,
>
> Going through this code, it's a bit hard to keep up ;-)
Here's how the structures are organized:
- A Kona clock is either a peripheral or a bus clock,
but a lot of things are handled generically at the
Kona level of abstraction.
- A peripheral clock has a selector (mux), up to two
dividers, and a gate. All of these are optional.
- A bus clock has a gate, which is optional. (There
are a few other things but I'm just ignoring them
for now.)
- Each of these sort of sub-components (gate, divider,
etc.) are handled on their own. In other words, there
are gate routines that operate on a gate regardless
of whether it's on bus or peripheral clock.
- These sub-components are grouped like this because
there are some weird gating requirements. (I've
said before I wanted to try to split things off where
possible to use the common framework code more, but
that opportunity hasn't arisen yet.)
> Does the call to __peri_clk_init enable the prereq clocks? If so, is
> their clk->prepare_count and clk->enable_count properly incremented?
My use of the term "enable" is imprecise.
The purpose of these *_init() routines is to set the hardware
to a known initial state. Right now, *defining* what that
state should be has not been sent out for review, but that's
the reason it's set up this way. The model is basically, when
you want to make a change, you record what the new value should
be and the *_commit() it. Special values, used at initialization
time, indicate we don't have a desired value but we don't know
what the hardware is currently is set to either. When those
special values (like BAD_SCALED_DIV_VALUE) are seen, the current
value is read from the hardware rather than written.
Anyway, to (hopefully) answer your question...
All of the prerequisite activity occurs in __kona_clk_init(),
which is called for every Kona clock. The first thing that
does is call __kona_prereq_init(), in order to set up and
initialize (using __kona_clk_init()) the prerequisite clock
if there is one.
*After* the prerequisite clock is set up, the rest of the
original clock initialization occurs, by calling (e.g.)
__peri_clk_init().
Sorry to be so verbose but I think it helps to understand
the design underlying this stuff.
I'm going to be submitting a new version of this series
today. It will pull out the clk_lookup field and
some comments that you spotted that are just dead code.
-Alex
> Thanks,
> Mike
>
>> + break;
>> default:
>> + ret = false;
>> BUG();
>> }
>> - return -EINVAL;
>> + if (ret)
>> + clk_set_initialized(bcm_clk);
>> +
>> + return ret;
>> }
>>
>> /* Set a CCU and all its clocks into their desired initial state */
>> diff --git a/drivers/clk/bcm/clk-kona.h b/drivers/clk/bcm/clk-kona.h
>> index 2537b30..10e238d 100644
>> --- a/drivers/clk/bcm/clk-kona.h
>> +++ b/drivers/clk/bcm/clk-kona.h
>> @@ -406,6 +406,7 @@ struct kona_clk {
>> struct clk_init_data init_data; /* includes name of this clock */
>> struct ccu_data *ccu; /* ccu this clock is associated with */
>> enum bcm_clk_type type;
>> + u32 flags; /* BCM_CLK_KONA_FLAGS_* below */
>> union {
>> void *data;
>> struct peri_clk_data *peri;
>> @@ -414,6 +415,12 @@ struct kona_clk {
>> #define to_kona_clk(_hw) \
>> container_of(_hw, struct kona_clk, hw)
>>
>> +/*
>> + * Kona clock flags:
>> + * INITIALIZED clock has been initialized already
>> + */
>> +#define BCM_CLK_KONA_FLAGS_INITIALIZED ((u32)1 << 0) /* Clock initialized */
>> +
>> /* Initialization macro for an entry in a CCU's kona_clks[] array. */
>> #define KONA_CLK(_ccu_name, _clk_name, _type) \
>> { \
>> --
>> 1.9.1
>>
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