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| author | Marc Zyngier <marc.zyngier@arm.com> | 2017-05-12 13:55:38 +0200 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2017-05-22 22:29:45 +0200 |
| commit | 53286669392b2d888f4b78b0e7894e022e668d11 (patch) | |
| tree | 59027a108e3689f69e17d2945ccfaf979dd7a74f /Documentation/IRQ-domain.txt | |
| parent | genirq/msi: Populate the domain name if provided by the irqchip (diff) | |
| download | linux-53286669392b2d888f4b78b0e7894e022e668d11.tar.xz linux-53286669392b2d888f4b78b0e7894e022e668d11.zip | |
Documentation: Update IRQ-domain.txt to document irq_domain_mapping
irq_domain_mapping is a rather useful tool to understand how IRqs
are mapped in irqdomains, and yet it is not documented anywhere.
Let's address this.
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Link: http://lkml.kernel.org/r/20170512115538.10767-5-marc.zyngier@arm.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'Documentation/IRQ-domain.txt')
| -rw-r--r-- | Documentation/IRQ-domain.txt | 41 |
1 files changed, 39 insertions, 2 deletions
diff --git a/Documentation/IRQ-domain.txt b/Documentation/IRQ-domain.txt index 82001a25a14b..1f246eb25ca5 100644 --- a/Documentation/IRQ-domain.txt +++ b/Documentation/IRQ-domain.txt @@ -231,5 +231,42 @@ needs to: 4) No need to implement irq_domain_ops.map and irq_domain_ops.unmap, they are unused with hierarchy irq_domain. -Hierarchy irq_domain may also be used to support other architectures, -such as ARM, ARM64 etc. +Hierarchy irq_domain is in no way x86 specific, and is heavily used to +support other architectures, such as ARM, ARM64 etc. + +=== Debugging === + +If you switch on CONFIG_IRQ_DOMAIN_DEBUG (which depends on +CONFIG_IRQ_DOMAIN and CONFIG_DEBUG_FS), you will find a new file in +your debugfs mount point, called irq_domain_mapping. This file +contains a live snapshot of all the IRQ domains in the system: + + name mapped linear-max direct-max devtree-node + pl061 8 8 0 /smb/gpio@e0080000 + pl061 8 8 0 /smb/gpio@e1050000 + pMSI 0 0 0 /interrupt-controller@e1101000/v2m@e0080000 + MSI 37 0 0 /interrupt-controller@e1101000/v2m@e0080000 + GICv2m 37 0 0 /interrupt-controller@e1101000/v2m@e0080000 + GICv2 448 448 0 /interrupt-controller@e1101000 + +it also iterates over the interrupts to display their mapping in the +domains, and makes the domain stacking visible: + + +irq hwirq chip name chip data active type domain + 1 0x00019 GICv2 0xffff00000916bfd8 * LINEAR GICv2 + 2 0x0001d GICv2 0xffff00000916bfd8 LINEAR GICv2 + 3 0x0001e GICv2 0xffff00000916bfd8 * LINEAR GICv2 + 4 0x0001b GICv2 0xffff00000916bfd8 * LINEAR GICv2 + 5 0x0001a GICv2 0xffff00000916bfd8 LINEAR GICv2 +[...] + 96 0x81808 MSI 0x (null) RADIX MSI + 96+ 0x00063 GICv2m 0xffff8003ee116980 RADIX GICv2m + 96+ 0x00063 GICv2 0xffff00000916bfd8 LINEAR GICv2 + 97 0x08800 MSI 0x (null) * RADIX MSI + 97+ 0x00064 GICv2m 0xffff8003ee116980 * RADIX GICv2m + 97+ 0x00064 GICv2 0xffff00000916bfd8 * LINEAR GICv2 + +Here, interrupts 1-5 are only using a single domain, while 96 and 97 +are build out of a stack of three domain, each level performing a +particular function. |