UPSTREAM: irqdomain: Allow domain lookup with DOMAIN_BUS_WIRED token

Let's take the (outlandish) example of an interrupt controller
capable of handling both wired interrupts and PCI MSIs.

With the current code, the PCI MSI domain is going to be tagged
with DOMAIN_BUS_PCI_MSI, and the wired domain with DOMAIN_BUS_ANY.

Things get hairy when we start looking up the domain for a wired
interrupt (typically when creating it based on some firmware
information - DT or ACPI).

In irq_create_fwspec_mapping(), we perform the lookup using
DOMAIN_BUS_ANY, which is actually used as a wildcard. This gives
us one chance out of two to end up with the wrong domain, and
we try to configure a wired interrupt with the MSI domain.
Everything grinds to a halt pretty quickly.

What we really need to do is to start looking for a domain that
would uniquely identify a wired interrupt domain, and only use
DOMAIN_BUS_ANY as a fallback.

In order to solve this, let's introduce a new DOMAIN_BUS_WIRED
token, which is going to be used exactly as described above.
Of course, this depends on the irqchip to setup the domain
bus_token, and nobody had to implement this so far.

Only so far.

Change-Id: Ia71c7475354eb38ab9b15423560aa3d28ae16381
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Frank Rowand <frowand.list@gmail.com>
Cc: Grant Likely <grant.likely@linaro.org>
Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Jiang Liu <jiang.liu@linux.intel.com>
Link: http://lkml.kernel.org/r/1453816347-32720-2-git-send-email-marc.zyngier@arm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Caesar Wang <wxt@rock-chips.com>
(cherry picked from commit 530cbe100ef7587aa5b5ac3a4b670cda4d50e598)

diff --git a/include/linux/irqdomain.h b/include/linux/irqdomain.h
index 4950a71ef77d450e4a01e3d177b235a4fba70c0d..8b60c95f4417d36e4f495ea92d3a9a2fa38e5165 100644 (file)
--- a/include/linux/irqdomain.h
+++ b/include/linux/irqdomain.h
@@ -70,6 +70,7 @@ struct irq_fwspec {
  */
 enum irq_domain_bus_token {
        DOMAIN_BUS_ANY          = 0,
+       DOMAIN_BUS_WIRED,
        DOMAIN_BUS_PCI_MSI,
        DOMAIN_BUS_PLATFORM_MSI,
        DOMAIN_BUS_NEXUS,

diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index 7f34d98ebfc45742e7c21d53dd0727fe6652aedf..6ca9bda5777c466c49853b42256733601fd4e3c5 100644 (file)
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -573,10 +573,15 @@ unsigned int irq_create_fwspec_mapping(struct irq_fwspec *fwspec)
        unsigned int type = IRQ_TYPE_NONE;
        int virq;
 
-       if (fwspec->fwnode)
-               domain = irq_find_matching_fwnode(fwspec->fwnode, DOMAIN_BUS_ANY);
-       else
+       if (fwspec->fwnode) {
+               domain = irq_find_matching_fwnode(fwspec->fwnode,
+                                                 DOMAIN_BUS_WIRED);
+               if (!domain)
+                       domain = irq_find_matching_fwnode(fwspec->fwnode,
+                                                         DOMAIN_BUS_ANY);
+       } else {
                domain = irq_default_domain;
+       }
 
        if (!domain) {
                pr_warn("no irq domain found for %s !\n",