The GICv5 architecture implements Interrupt Translation Service
(ITS) components in order to translate events coming from peripherals
into interrupt events delivered to the connected IRSes.
Events (ie MSI memory writes to ITS translate frame), are translated
by the ITS using tables kept in memory.
ITS translation tables for peripherals is kept in memory storage
(device table [DT] and Interrupt Translation Table [ITT]) that
is allocated by the driver on boot.
Both tables can be 1- or 2-level; the structure is chosen by the
driver after probing the ITS HW parameters and checking the
allowed table splits and supported {device/event}_IDbits.
DT table entries are allocated on demand (ie when a device is
probed); the DT table is sized using the number of supported
deviceID bits in that that's a system design decision (ie the
number of deviceID bits implemented should reflect the number
of devices expected in a system) therefore it makes sense to
allocate a DT table that can cater for the maximum number of
devices.
DT and ITT tables are allocated using the kmalloc interface;
the allocation size may be smaller than a page or larger,
and must provide contiguous memory pages.
LPIs INTIDs backing the device events are allocated one-by-one
and only upon Linux IRQ allocation; this to avoid preallocating
a large number of LPIs to cover the HW device MSI vector
size whereas few MSI entries are actually enabled by a device.
ITS cacheability/shareability attributes are programmed
according to the provided firmware ITS description.
The GICv5 partially reuses the GICv3 ITS MSI parent infrastructure
and adds functions required to retrieve the ITS translate frame
addresses out of msi-map and msi-parent properties to implement
the GICv5 ITS MSI parent callbacks.
Co-developed-by: Sascha Bischoff <sascha.bischoff@arm.com>
Signed-off-by: Sascha Bischoff <sascha.bischoff@arm.com>
Co-developed-by: Timothy Hayes <timothy.hayes@arm.com>
Signed-off-by: Timothy Hayes <timothy.hayes@arm.com>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20250703-gicv5-host-v7-28-12e71f1b3528@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
An IRS supports Logical Peripheral Interrupts (LPIs) and implement
Linux IPIs on top of it.
LPIs are used for interrupt signals that are translated by a
GICv5 ITS (Interrupt Translation Service) but also for software
generated IRQs - namely interrupts that are not driven by a HW
signal, ie IPIs.
LPIs rely on memory storage for interrupt routing and state.
LPIs state and routing information is kept in the Interrupt
State Table (IST).
IRSes provide support for 1- or 2-level IST tables configured
to support a maximum number of interrupts that depend on the
OS configuration and the HW capabilities.
On systems that provide 2-level IST support, always allow
the maximum number of LPIs; On systems with only 1-level
support, limit the number of LPIs to 2^12 to prevent
wasting memory (presumably a system that supports a 1-level
only IST is not expecting a large number of interrupts).
On a 2-level IST system, L2 entries are allocated on
demand.
The IST table memory is allocated using the kmalloc() interface;
the allocation required may be smaller than a page and must be
made up of contiguous physical pages if larger than a page.
On systems where the IRS is not cache-coherent with the CPUs,
cache mainteinance operations are executed to clean and
invalidate the allocated memory to the point of coherency
making it visible to the IRS components.
On GICv5 systems, IPIs are implemented using LPIs.
Add an LPI IRQ domain and implement an IPI-specific IRQ domain created
as a child/subdomain of the LPI domain to allocate the required number
of LPIs needed to implement the IPIs.
IPIs are backed by LPIs, add LPIs allocation/de-allocation
functions.
The LPI INTID namespace is managed using an IDA to alloc/free LPI INTIDs.
Associate an IPI irqchip with IPI IRQ descriptors to provide
core code with the irqchip.ipi_send_single() method required
to raise an IPI.
Co-developed-by: Sascha Bischoff <sascha.bischoff@arm.com>
Signed-off-by: Sascha Bischoff <sascha.bischoff@arm.com>
Co-developed-by: Timothy Hayes <timothy.hayes@arm.com>
Signed-off-by: Timothy Hayes <timothy.hayes@arm.com>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Cc: Will Deacon <will@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20250703-gicv5-host-v7-22-12e71f1b3528@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
The GICv5 Interrupt Routing Service (IRS) component implements
interrupt management and routing in the GICv5 architecture.
A GICv5 system comprises one or more IRSes, that together
handle the interrupt routing and state for the system.
An IRS supports Shared Peripheral Interrupts (SPIs), that are
interrupt sources directly connected to the IRS; they do not
rely on memory for storage. The number of supported SPIs is
fixed for a given implementation and can be probed through IRS
IDR registers.
SPI interrupt state and routing are managed through GICv5
instructions.
Each core (PE in GICv5 terms) in a GICv5 system is identified with
an Interrupt AFFinity ID (IAFFID).
An IRS manages a set of cores that are connected to it.
Firmware provides a topology description that the driver uses
to detect to which IRS a CPU (ie an IAFFID) is associated with.
Use probeable information and firmware description to initialize
the IRSes and implement GICv5 IRS SPIs support through an
SPI-specific IRQ domain.
The GICv5 IRS driver:
- Probes IRSes in the system to detect SPI ranges
- Associates an IRS with a set of cores connected to it
- Adds an IRQchip structure for SPI handling
SPIs priority is set to a value corresponding to the lowest
permissible priority in the system (taking into account the
implemented priority bits of the IRS and CPU interface).
Since all IRQs are set to the same priority value, the value
itself does not matter as long as it is a valid one.
Co-developed-by: Sascha Bischoff <sascha.bischoff@arm.com>
Signed-off-by: Sascha Bischoff <sascha.bischoff@arm.com>
Co-developed-by: Timothy Hayes <timothy.hayes@arm.com>
Signed-off-by: Timothy Hayes <timothy.hayes@arm.com>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Cc: Will Deacon <will@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Marc Zyngier <maz@kernel.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20250703-gicv5-host-v7-21-12e71f1b3528@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
