[PATCH V2 1/4] cpufreq: add arm soc generic cpufreq driver

[Arnd Bergmann]

On Saturday 17 December 2011 16:00:03 Richard Zhao wrote:
> On Fri, Dec 16, 2011 at 08:32:35AM -0600, Rob Herring wrote:
> > On 12/16/2011 04:30 AM, Richard Zhao wrote:
> > > It support single core and multi-core ARM SoCs. But it assume
> > > all cores share the same frequency and voltage.
> > > 
> > > Signed-off-by: Richard Zhao <richard.zhao at linaro.org>
> > > ---
> > >  drivers/cpufreq/Kconfig.arm   |    8 ++
> > >  drivers/cpufreq/Makefile      |    1 +
> > >  drivers/cpufreq/arm-cpufreq.c |  269 +++++++++++++++++++++++++++++++++++++++++
> > >  3 files changed, 278 insertions(+), 0 deletions(-)
> > >  create mode 100644 drivers/cpufreq/arm-cpufreq.c
> > > 
> > 
> > What makes this specific to ARM and not a generic DT + clk api +
> > regulator api driver?
>
> smp loops_per_jiffy update needs arm header <asm/cpu.h>.

I would suggest to instead change the definition of adjust_jiffies in the
core so it can be overridden by the architecture, like this

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 987a165..174584d 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -189,6 +189,7 @@ EXPORT_SYMBOL_GPL(cpufreq_cpu_put);
  * systems as each CPU might be scaled differently. So, use the arch
  * per-CPU loops_per_jiffy value wherever possible.
  */
+#ifndef adjust_jiffies
 #ifndef CONFIG_SMP
 static unsigned long l_p_j_ref;
 static unsigned int  l_p_j_ref_freq;
@@ -218,7 +219,8 @@ static inline void adjust_jiffies(unsigned long val, struct cpufreq_freqs *ci)
 {
        return;
 }
-#endif
+#endif /* CONFIG_SMP */
+#endif /* adjust_jiffies */
 
 
 /**


Then ARM (and any others that want the driver) can provide their own
implementation and set 

#define adjust_jiffies(val, ci) adjust_jiffies((val), (ci))

to let the core use that instead of the generic UP version.


While we're there, we should probably try to fix drivers that use loops_per_jiffy,
because that is not what they think it is on SMP.

	Arnd