[PATCH v3 1/3] ARM: shmobile: sh73a0: wait for completion when kicking the clock

[Simon Horman]

On Fri, Mar 01, 2013 at 11:52:25AM +0900, Simon Horman wrote:
> On Thu, Feb 28, 2013 at 01:21:58PM +0100, Guennadi Liakhovetski wrote:
> > To reconfigure clocks, controlled by FRQCRA and FRQCRB, a kick bit has to
> > be set and to make sure the setting has taken effect, it has to be read
> > back repeatedly until it is cleared by the hardware. This patch adds the
> > waiting part, that was missing until now.
> > 
> > Signed-off-by: Guennadi Liakhovetski <g.liakhovetski at gmx.de>
> 
> This patch seems to be ready to be applied.
> 
> Magnus, could I get a review from you?

Magnus, ping.

> > ---
> > 
> > As noted in patch 0/3, this patch affects existing systems, but AFAICS 
> > only theoretically - so far nobody is changing clock rates of any of the 
> > FRQCRA and FRQCRB clocks. Still, please, handle with care.
> > 
> >  arch/arm/mach-shmobile/clock-sh73a0.c |   23 +++++++++++++++++------
> >  1 files changed, 17 insertions(+), 6 deletions(-)
> > 
> > diff --git a/arch/arm/mach-shmobile/clock-sh73a0.c b/arch/arm/mach-shmobile/clock-sh73a0.c
> > index 71843dd..34b5c5a 100644
> > --- a/arch/arm/mach-shmobile/clock-sh73a0.c
> > +++ b/arch/arm/mach-shmobile/clock-sh73a0.c
> > @@ -21,6 +21,7 @@
> >  #include <linux/io.h>
> >  #include <linux/sh_clk.h>
> >  #include <linux/clkdev.h>
> > +#include <asm/processor.h>
> >  #include <mach/common.h>
> >  
> >  #define FRQCRA		IOMEM(0xe6150000)
> > @@ -234,14 +235,24 @@ static struct clk *main_clks[] = {
> >  	&sh73a0_extalr_clk,
> >  };
> >  
> > -static void div4_kick(struct clk *clk)
> > +static int frqcr_kick(void)
> >  {
> > -	unsigned long value;
> > +	int i;
> > +
> > +	/* set KICK bit in FRQCRB to update hardware setting, check success */
> > +	__raw_writel(__raw_readl(FRQCRB) | (1 << 31), FRQCRB);
> > +	for (i = 1000; i; i--)
> > +		if (__raw_readl(FRQCRB) & (1 << 31))
> > +			cpu_relax();
> > +		else
> > +			return i;
> > +
> > +	return -ETIMEDOUT;
> > +}
> >  
> > -	/* set KICK bit in FRQCRB to update hardware setting */
> > -	value = __raw_readl(FRQCRB);
> > -	value |= (1 << 31);
> > -	__raw_writel(value, FRQCRB);
> > +static void div4_kick(struct clk *clk)
> > +{
> > +	frqcr_kick();
> >  }
> >  
> >  static int divisors[] = { 2, 3, 4, 6, 8, 12, 16, 18,
> > -- 
> > 1.7.2.5
> > 
> > --
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