[PATCH v3 2/5] usb: chipidea: add freescale imx28 special write register method

[gregkh at linuxfoundation.org]

On Mon, Oct 28, 2013 at 11:47:53AM +0100, Marek Vasut wrote:
> Dear Hector Palacios,
> 
> > Dear Peter,
> > 
> > On 10/25/2013 08:02 AM, Peter Chen wrote:
> > > According to Freescale imx28 Errata, "ENGR119653 USB: ARM to USB
> > > register error issue", All USB register write operations must
> > > use the ARM SWP instruction. So, we implement special hw_write
> > > and hw_test_and_clear for imx28.
> > > 
> > > Discussion for it at below:
> > > http://marc.info/?l=linux-usb&m=137996395529294&w=2
> > > 
> > > Signed-off-by: Peter Chen
> > > <peter.chen-KZfg59tc24xl57MIdRCFDg at public.gmane.org> ---
> > > Changes for v2:
> > > - Rebase to latest usb-next tree
> > > 
> > >   drivers/usb/chipidea/ci.h    |   23 +++++++++++++++++++++++
> > >   drivers/usb/chipidea/core.c  |    2 ++
> > >   drivers/usb/chipidea/host.c  |    1 +
> > >   include/linux/usb/chipidea.h |    1 +
> > >   4 files changed, 27 insertions(+), 0 deletions(-)
> > > 
> > > diff --git a/drivers/usb/chipidea/ci.h b/drivers/usb/chipidea/ci.h
> > > index 1c94fc5..4eb61d0 100644
> > > --- a/drivers/usb/chipidea/ci.h
> > > +++ b/drivers/usb/chipidea/ci.h
> > > @@ -173,6 +173,8 @@ struct ci_hdrc {
> > > 
> > >   	struct dentry			*debugfs;
> > >   	bool				id_event;
> > >   	bool				b_sess_valid_event;
> > > 
> > > +	/* imx28 needs swp instruction for writing */
> > > +	bool				imx28_write_fix;
> > > 
> > >   };
> > >   
> > >   static inline struct ci_role_driver *ci_role(struct ci_hdrc *ci)
> > > 
> > > @@ -253,6 +255,13 @@ static inline u32 hw_read(struct ci_hdrc *ci, enum
> > > ci_hw_regs reg, u32 mask)
> > > 
> > >   	return ioread32(ci->hw_bank.regmap[reg]) & mask;
> > >   
> > >   }
> > > 
> > > +#ifdef CONFIG_SOC_IMX28
> > > +static inline void imx28_ci_writel(u32 val32, volatile u32 *addr)
> > > +{
> > > +	__asm__ ("swp %0, %0, [%1]" : : "r"(val32), "r"(addr));
> > > +}
> > > +#endif
> > > +
> > > 
> > >   /**
> > >   
> > >    * hw_write: writes to a hw register
> > >    * @reg:  register index
> > > 
> > > @@ -266,7 +275,14 @@ static inline void hw_write(struct ci_hdrc *ci, enum
> > > ci_hw_regs reg,
> > > 
> > >   		data = (ioread32(ci->hw_bank.regmap[reg]) & ~mask)
> > >   		
> > >   			| (data & mask);
> > > 
> > > +#ifdef CONFIG_SOC_IMX28
> > > +	if (ci->imx28_write_fix)
> > > +		imx28_ci_writel(data, ci->hw_bank.regmap[reg]);
> > > +	else
> > > +		iowrite32(data, ci->hw_bank.regmap[reg]);
> > > +#else
> > > 
> > >   	iowrite32(data, ci->hw_bank.regmap[reg]);
> > > 
> > > +#endif
> > > 
> > >   }
> > >   
> > >   /**
> > > 
> > > @@ -281,7 +297,14 @@ static inline u32 hw_test_and_clear(struct ci_hdrc
> > > *ci, enum ci_hw_regs reg,
> > > 
> > >   {
> > >   
> > >   	u32 val = ioread32(ci->hw_bank.regmap[reg]) & mask;
> > > 
> > > +#ifdef CONFIG_SOC_IMX28
> > > +	if (ci->imx28_write_fix)
> > > +		imx28_ci_writel(val, ci->hw_bank.regmap[reg]);
> > > +	else
> > > +		iowrite32(val, ci->hw_bank.regmap[reg]);
> > > +#else
> > > 
> > >   	iowrite32(val, ci->hw_bank.regmap[reg]);
> > > 
> > > +#endif
> > > 
> > >   	return val;
> > >   
> > >   }
> > 
> > Can't we remove the #ifdefs CONFIG_SOC_IMX28 all around?
> > The check is done on the new flag ci->imx28_write_fix which exists for all
> > platforms, isn't it?.
> 
> The SWP instruction is specific to ARM, so you'd need to stub-out the 
> imx28_ci_writel() with ifdef then.

That's better than the mess of #ifdefs this patch adds, which isn't ok
at all :(