[RFC PATCH v2] drivers: bus: add ARM CCI support

[Lorenzo Pieralisi]

On Fri, May 03, 2013 at 04:17:07PM +0100, Javi Merino wrote:
> Hi Lorenzo,
> 
> On Wed, May 01, 2013 at 05:18:28PM +0100, Lorenzo Pieralisi wrote:
> > On ARM multi-cluster systems coherency between cores running on
> > different clusters is managed by the cache-coherent interconnect (CCI).
> > It allows broadcasting of TLB invalidates and memory barriers and it
> > guarantees cache coherency at system level through snooping of slave
> > interfaces connected to it.
> > 
> > This patch enables the basic infrastructure required in Linux to handle and
> > programme the CCI component.
> > 
> > Non-local variables used by the CCI management functions called by power
> > down function calls after disabling the cache must be flushed out to main
> > memory in advance, otherwise incoherency of those values may occur if they
> > are sitting in the cache of some other CPU when power down functions
> > execute. Driver code ensures that relevant data structures are flushed
> > from inner and outer caches after the driver probe is completed.
> > 
> > CCI slave port resources are linked to set of CPUs through bus masters
> > phandle properties that link the interface resources to masters node in
> > the device tree.
> > 
> > Documentation describing the CCI DT bindings is provided with the patch.
> > 
> > Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>
> > ---
> 
> [...]
> 
> > diff --git a/include/linux/arm-cci.h b/include/linux/arm-cci.h
> > new file mode 100644
> > index 0000000..0e70942
> > --- /dev/null
> > +++ b/include/linux/arm-cci.h
> > @@ -0,0 +1,59 @@
> > +/*
> > + * CCI cache coherent interconnect support
> > + *
> > + * Copyright (C) 2013 ARM Ltd.
> > + *
> > + * This program is free software; you can redistribute it and/or modify
> > + * it under the terms of the GNU General Public License as published by
> > + * the Free Software Foundation; either version 2 of the License, or
> > + * (at your option) any later version.
> > + *
> > + * This program is distributed in the hope that it will be useful,
> > + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> > + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> > + * GNU General Public License for more details.
> > + *
> > + * You should have received a copy of the GNU General Public License
> > + * along with this program; if not, write to the Free Software
> > + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
> > + */
> > +
> > +#ifndef __LINUX_ARM_CCI_H
> > +#define __LINUX_ARM_CCI_H
> > +
> > +#include <linux/errno.h>
> > +#include <linux/types.h>
> > +
> > +struct device_node;
> > +
> > +#ifdef CONFIG_ARM_CCI
> > +extern int cci_ace_get_port(struct device_node *dn);
> > +extern int cci_disable_port_by_cpu(u64 mpidr);
> > +extern int __cci_control_port_by_device(struct device_node *dn, bool enable);
> > +extern int __cci_control_port_by_index(u32 port, bool enable);
> > +#else
> > +static inline int cci_ace_get_port(struct device_node *dn, bool cpu)
> 
> Builds with !CONFIG_ARM_CCI fail because this definition of
> cci_ace_get_port() takes two arguments whereas the one for
> CONFIG_ARM_CCI takes only one.

Yes, sorry, I missed that while refactoring the interface.

Thanks,
Lorenzo