linux-stable.git/arch/mips/kernel/mips-cm.c, branch linux-rolling-stable

MIPS: CPS: Improve mips_cps_first_online_in_cluster()

2025-07-16T16:34:49+00:00

The initial implementation of this function goes through all the CPUs
in a cluster to determine if the current CPU is the only one
running. This process occurs every time the function is called.

However, during boot, we already perform this task, so let's take
advantage of this opportunity to create and fill a CPU bitmask that
can be easily and efficiently used later.

This patch modifies the function to allow providing the first
available online CPU when one already exists, which is necessary for
delay CPU calibration optimization.

Reviewed-by: Jiaxun Yang 
Signed-off-by: Gregory CLEMENT 
Signed-off-by: Thomas Bogendoerfer

MIPS: disable MMID when not supported by the hardware

2025-07-16T16:34:36+00:00

It is possible that MMID is supported at the CPU level, but its
integration in a SoC prevents its usage. For instance, if the
System-level Interconnect (also known as Network on Chip) does not
support global invalidation, then the MMID feature is not usable. The
current implementation of MMID relies on the GINV* instructions.

This patch allows the disabling of MMID based on a device tree
property, as this issue cannot be detected at runtime.

MMID is set up very early during the boot process, even before device
tree data can be accessed. Therefore, when we determine whether MMID
needs to be disabled, some MMID setup has already been performed for
the boot CPU. Consequently, we must revert the MMID setup on the first
CPU before disabling the feature for the subsequent CPUs that will be
initialized later.

Signed-off-by: Gregory CLEMENT 
Signed-off-by: Thomas Bogendoerfer

MIPS: cm: Detect CM quirks from device tree

2025-02-21T13:49:21+00:00

Some information that should be retrieved at runtime for the Coherence
Manager can be either absent or wrong. This patch allows checking if
some of this information is available from the device tree and updates
the internal variable accordingly.

For now, only the compatible string associated with the broken HCI is
being retrieved.

Signed-off-by: Gregory CLEMENT 
Signed-off-by: Thomas Bogendoerfer

MIPS: CPS: Boot CPUs in secondary clusters

2025-02-21T09:19:37+00:00

Probe for & boot CPUs (cores & VPs) in secondary clusters (ie. not the
cluster that began booting Linux) when they are present in systems with
CM 3.5 or higher.

Signed-off-by: Paul Burton 
Signed-off-by: Chao-ying Fu 
Signed-off-by: Dragan Mladjenovic 
Signed-off-by: Aleksandar Rikalo 
Tested-by: Serge Semin 
Tested-by: Gregory CLEMENT 
Signed-off-by: Thomas Bogendoerfer

MIPS: CPS: Add a couple of multi-cluster utility functions

2024-07-09T08:48:17+00:00

This patch introduces a couple of utility functions which help later
patches with introducing support for multi-cluster systems.

 - mips_cps_multicluster_cpus() allows its caller to determine whether
   the system includes CPUs spread across multiple clusters. This is
   useful because in some cases behaviour can be more optimal taking
   this knowledge into account. The means by which we check this is
   dependent upon the way we probe CPUs & assign their numbers, so
   keeping this knowledge confined here in arch/mips/ seems appropriate.

 - mips_cps_first_online_in_cluster() allows its caller to determine
   whether it is running upon the first CPU online within its cluster.
   This information is useful in cases where some cluster-wide
   configuration may need to occur, but should not be repeated if
   another CPU in the cluster is already online. Similarly to the above
   this is determined based upon knowledge of CPU numbering so it makes
   sense to keep that knowledge in arch/mips/. The function is defined
   in mips-cm.c rather than in asm/mips-cps.h in order to allow us to
   use asm/cpu-info.h & linux/smp.h without encountering an include
   nightmare.

Signed-off-by: Paul Burton 
Signed-off-by: Chao-ying Fu 
Signed-off-by: Dragan Mladjenovic 
Signed-off-by: Aleksandar Rikalo 
Signed-off-by: Thomas Bogendoerfer

mips: cm: Convert __mips_cm_phys_base() to weak function

2024-03-11T13:02:15+00:00

Based on the design pattern utilized in the CM GCR base address getter
implementation, the platform-specific code is capable to re-define the
getter and re-use the weakly defined initial version. But since the
pattern hasn't been used for over 10 years and another similar case (CM
L2-sync only base address getter) has just been fixed, let's unify the
interface and convert it to a more traditional single weakly defined
method: mips_cm_phys_base() (see the link below for the discussion around
this).

Link: https://lore.kernel.org/linux-mips/20240215171740.14550-3-fancer.lancer@gmail.com
Signed-off-by: Serge Semin 
Signed-off-by: Thomas Bogendoerfer

mips: cm: Convert __mips_cm_l2sync_phys_base() to weak function

2024-03-11T13:02:11+00:00

The __mips_cm_l2sync_phys_base() and mips_cm_l2sync_phys_base() couple was
introduced in commit 9f98f3dd0c51 ("MIPS: Add generic CM probe & access
code") where the former method was a weak implementation of the later
function. Such design pattern permitted to re-define the original method
and to use the weak implementation in the new function. A similar approach
was introduced in the framework of another arch-specific programmable
interface: mips_cm_phys_base() and __mips_cm_phys_base(). The only
difference is that the underscored method of the later couple was declared
in the "asm/mips-cm.h" header file, but it wasn't done for the CM L2-sync
methods in the subject. Due to the missing global function declaration
the "missing prototype" warning was spotted in the framework of the commit
9a2036724cd6 ("mips: mark local function static if possible") and fixed
just be re-qualifying the weak method as static. Doing that broke what was
originally implied by having the weak implementation globally defined.

Let's fix the broken CM2 L2-sync arch-interface by dropping the static
qualifier and, seeing the implemented pattern hasn't been used for over 10
years but will be required soon (see the link for the discussion around
it), converting it to a single weakly defined method:
mips_cm_l2sync_phys_base().

Fixes: 9a2036724cd6 ("mips: mark local function static if possible")
Link: https://lore.kernel.org/linux-mips/20240215171740.14550-3-fancer.lancer@gmail.com
Signed-off-by: Serge Semin 
Signed-off-by: Thomas Bogendoerfer

mips: mark local function static if possible

2023-12-11T01:21:39+00:00

These two functions are global but have no extern prototypes or other
callers, so it's best to mark them as static, avoiding these warnings:

arch/mips/kernel/mips-cm.c:204:13: error: no previous prototype for '__mips_cm_l2sync_phys_base' [-Werror=missing-prototypes]
arch/mips/mm/c-r4k.c:1827:12: error: no previous prototype for 'r4k_cache_init_pm' [-Werror=missing-prototypes]

Link: https://lkml.kernel.org/r/20231204115710.2247097-7-arnd@kernel.org
Signed-off-by: Arnd Bergmann 
Cc: Stephen Rothwell 
Cc: Thomas Bogendoerfer 
Signed-off-by: Andrew Morton

MIPS: mips-cm: Check availability of config registers

2023-04-05T07:45:08+00:00

Prevent reading unsupported config register during probing process.

Signed-off-by: Jiaxun Yang 
Signed-off-by: Thomas Bogendoerfer

mips: cm: Convert to bitfield API to fix out-of-bounds access

2021-11-02T09:53:52+00:00

mips_cm_error_report() extracts the cause and other cause from the error
register using shifts.  This works fine for the former, as it is stored
in the top bits, and the shift will thus remove all non-related bits.
However, the latter is stored in the bottom bits, hence thus needs masking
to get rid of non-related bits.  Without such masking, using it as an
index into the cm2_causes[] array will lead to an out-of-bounds access,
probably causing a crash.

Fix this by using FIELD_GET() instead.  Bite the bullet and convert all
MIPS CM handling to the bitfield API, to improve readability and safety.

Fixes: 3885c2b463f6a236 ("MIPS: CM: Add support for reporting CM cache errors")
Signed-off-by: Geert Uytterhoeven 
Reviewed-by: Jiaxun Yang 
Signed-off-by: Thomas Bogendoerfer