Subject: [PATCH v2 2/2] ARM: imx53: globally disable supervisor protect

From: [email-masked] (Shawn Guo)
Date: Tue, 1 Jul 2014 13:24:39 +0800

On Mon, Jun 30, 2014 at 09:04:21AM +0200, Steffen Trumtrar wrote:
> Hi!
> 
> On Mon, Jun 30, 2014 at 12:12:27PM +0800, Shawn Guo wrote:
> > On Wed, Jun 25, 2014 at 01:01:31PM +0200, Steffen Trumtrar wrote:
> > > Most peripherals on the i.MX53 have an
> > > 	Off-Platform Peripheral Access Control Register (OPACR)
> > > in which the access rights (together with the MPROT registers) can be declared.
> > > However, this does not seem to work for example for SSI1+SDMA, because the
> > > supervisor bit is not set for the SDMA unit.
> > > It does work for SSI2, the QSB for example uses SSI2 for its audio. But SSI2 only
> > > works because it does NOT have an OPACR.
> > > 
> > > The right solution would be to fix the access rights for the SDMA, but the unit
> > > responsible for this is the Central Security Unit (CSU), which of course is NOT
> > > documented. So, until documentation for this is openly available, turn off the
> > > supervisor protection because it cripples the hardware.
> > > 
> > > Signed-off-by: Steffen Trumtrar <[email-masked]>
> > > ---
> > >  arch/arm/mach-imx/mach-imx53.c | 14 ++++++++++++++
> > >  1 file changed, 14 insertions(+)
> > > 
> > > diff --git a/arch/arm/mach-imx/mach-imx53.c b/arch/arm/mach-imx/mach-imx53.c
> > > index 2bad387..380c7ee 100644
> > > --- a/arch/arm/mach-imx/mach-imx53.c
> > > +++ b/arch/arm/mach-imx/mach-imx53.c
> > > @@ -15,6 +15,7 @@
> > >  #include <linux/err.h>
> > >  #include <linux/io.h>
> > >  #include <linux/irq.h>
> > > +#include <linux/of_address.h>
> > >  #include <linux/of_irq.h>
> > >  #include <linux/of_platform.h>
> > >  #include <asm/mach/arch.h>
> > > @@ -24,11 +25,24 @@
> > >  #include "hardware.h"
> > >  #include "mx53.h"
> > >  
> > > +static const struct of_device_id aips_of_matches[] __initconst = {
> > > +	{ .compatible = "fsl,imx53-aipstz" },
> > > +	{ /*sentinel*/ }
> > > +};
> > > +
> > >  static void __init imx53_dt_init(void)
> > >  {
> > > +	void __iomem *aips_base_addr;
> > > +	struct device_node *np;
> > > +
> > >  	mxc_arch_reset_init_dt();
> > >  
> > >  	of_platform_populate(NULL, of_default_bus_match_table, NULL, NULL);
> > > +
> > > +	for_each_matching_node(np, aips_of_matches) {
> > > +		aips_base_addr = of_iomap(np, 0);
> > > +		imx_set_aips(aips_base_addr);
> > > +	}
> > 
> > The same code pattern might be needed for i.MX31 and i.MX35 device tree
> > support later.  Can we have a helper for it, so that i.MX3 DT conversion
> > can benefit from it?
> > 
> 
> What would be the best place to put this? common.h?

How about the same place as imx_set_aips()?

> Maybe we should then also rename the imx_set_aips to imx_disable_supervisor,
> because that is basically what the function does.

I'm fine with either way.

> If I understood our graphics department correctly, the i.MX6 needs this, too,
> for the VPU (?).

Hmm, I do not see this setup for i.MX6 in FSL kernel tree.  Is it being
done at somewhere else?

Shawn