On Monday, September 14, 2015 05:44:01 PM Marc Zyngier wrote:
> struct device_node is very much DT specific, and the original authors
> of the irqdomain subsystem recognized that tie, and went as far as
> mentionning that this could be replaced by some "void *token",
> should another firmware infrastructure be using it.
>
> As we move ACPI on arm64 towards this model too, it makes a lot of sense
> to perform that particular move.
>
> We replace "struct device_node *of_node" with "void *domain_token", which
> is a benign enough transformation. A non DT user of irqdomain can now
> identify its domains using this pointer.
>
> Also, in order to prevent the introduction of sideband type information,
> only DT is allowed to store a valid kernel pointer in domain_token
> (a pointer that passes the virt_addr_valid() test will be considered
> as a valid device_node).
>
> non-DT users that wish to store valid pointers in domain_token are
> required to use another structure such as an IDR.
>
> Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
> ---
> include/linux/irqdomain.h | 68 +++++++++++++++++++-----------------
> kernel/irq/irqdomain.c | 89 ++++++++++++++++++++++++++++++++++-------------
> 2 files changed, 101 insertions(+), 56 deletions(-)
>
> diff --git a/include/linux/irqdomain.h b/include/linux/irqdomain.h
> index f644fdb..ac7041b 100644
> --- a/include/linux/irqdomain.h
> +++ b/include/linux/irqdomain.h
> @@ -17,16 +17,14 @@
> * model). It's the domain callbacks that are responsible for setting the
> * irq_chip on a given irq_desc after it's been mapped.
> *
> - * The host code and data structures are agnostic to whether or not
> - * we use an open firmware device-tree. We do have references to struct
> - * device_node in two places: in irq_find_host() to find the host matching
> - * a given interrupt controller node, and of course as an argument to its
> - * counterpart domain->ops->match() callback. However, those are treated as
> - * generic pointers by the core and the fact that it's actually a device-node
> - * pointer is purely a convention between callers and implementation. This
> - * code could thus be used on other architectures by replacing those two
> - * by some sort of arch-specific void * "token" used to identify interrupt
> - * controllers.
> + * The host code and data structures are agnostic to whether or not we
> + * use an open firmware device-tree. Domains can be assigned a
> + * "void *domain_token" identifier, which is assumed to represent a
> + * "struct device_node" if the pointer is a valid virtual address.
> + *
> + * Otherwise, the value is assumed to be an opaque identifier. Should
> + * a pointer to a non "struct device_node" be required, another data
> + * structure should be used to indirect it (an IDR for example).
> */
>
> #ifndef _LINUX_IRQDOMAIN_H
> @@ -108,8 +106,8 @@ struct irq_domain_chip_generic;
> * @flags: host per irq_domain flags
> *
> * Optional elements
> - * @of_node: Pointer to device tree nodes associated with the irq_domain. Used
> - * when decoding device tree interrupt specifiers.
> + * @domain_token: optional firmware-specific identifier for
> + * the interrupt controller
> * @gc: Pointer to a list of generic chips. There is a helper function for
> * setting up one or more generic chips for interrupt controllers
> * drivers using the generic chip library which uses this pointer.
> @@ -130,7 +128,7 @@ struct irq_domain {
> unsigned int flags;
>
> /* Optional data */
> - struct device_node *of_node;
> + void *domain_token;
I'm wondering if that may be something which isn't (void *), but a specific
pointer type, so the compiler warns us when something suspicious is assigned
to it?
[Somewhat along the lines struct fwnode_handle is used elsewehere.]
> enum irq_domain_bus_token bus_token;
> struct irq_domain_chip_generic *gc;
> #ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
> @@ -161,70 +159,73 @@ enum {
Thanks,
Rafael
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