We end up with:

ERROR: "HYPERVISOR_event_channel_op" [drivers/xen/xen-gntdev.ko] undefined!
ERROR: "privcmd_call" [drivers/xen/xen-privcmd.ko] undefined!
ERROR: "HYPERVISOR_grant_table_op" [drivers/net/xen-netback/xen-netback.ko] undefined!

and this patch exports said function (which is implemented in hypercall.S).
Acked-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: NIan Campbell <ian.campbell@citrix.com>
Signed-off-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Only until we get the balloon driver to work.
Signed-off-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Compile events.c on ARM.
Parse, map and enable the IRQ to get event notifications from the device
tree (node "/xen").
Signed-off-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Initialize the grant table mapping at the address specified at index 0
in the DT under the /xen node.
After the grant table is initialized, call xenbus_probe (if not dom0).

Changes in v2:

- introduce GRANT_TABLE_PHYSADDR;
- remove unneeded initialization of boot_max_nr_grant_frames.
Signed-off-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>

Use Xen features to figure out if we are privileged.

XENFEAT_dom0 was introduced by 23735 in xen-unstable.hg.
Signed-off-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>

Check for a node in the device tree compatible with "xen,xen", if it is
present set xen_domain_type to XEN_HVM_DOMAIN and continue
initialization.

Map the real shared info page using XENMEM_add_to_physmap with
XENMAPSPACE_shared_info.

Changes in v4:

- simpler parsing of Xen version in the compatible DT node.

Changes in v3:

- use the "xen,xen" notation rather than "arm,xen";
- add an additional check on the presence of the Xen version.

Changes in v2:

- replace pr_info with pr_debug.
Signed-off-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>

- Basic hypervisor.h and interface.h definitions.
- Skeleton enlighten.c, set xen_start_info to an empty struct.
- Make xen_initial_domain dependent on the SIF_PRIVILIGED_BIT.

The new code only compiles when CONFIG_XEN is set, that is going to be
added to arch/arm/Kconfig in patch #11 "xen/arm: introduce CONFIG_XEN on
ARM".

Changes in v3:

- improve comments.
Signed-off-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: NKonrad Rzeszutek Wilk <konrad.wilk@oracle.com>