linux.git/drivers/base/regmap/regcache-maple.c, branch v6.12.80 Clone of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git regmap: maple: free entry on mas_store_gfp() failure 2026-02-11T12:40:23+00:00 Kaushlendra Kumar kaushlendra.kumar@intel.com 2026-01-05T03:18:20+00:00 811b45e2d795d955bb7fd9c816b40036f4fde350 [ Upstream commit f3f380ce6b3d5c9805c7e0b3d5bc28d9ec41e2e8 ] regcache_maple_write() allocates a new block ('entry') to merge adjacent ranges and then stores it with mas_store_gfp(). When mas_store_gfp() fails, the new 'entry' remains allocated and is never freed, leaking memory. Free 'entry' on the failure path; on success continue freeing the replaced neighbor blocks ('lower', 'upper'). Signed-off-by: Kaushlendra Kumar <kaushlendra.kumar@intel.com> Link: https://patch.msgid.link/20260105031820.260119-1-kaushlendra.kumar@intel.com Signed-off-by: Mark Brown <broonie@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit f3f380ce6b3d5c9805c7e0b3d5bc28d9ec41e2e8 ]

regcache_maple_write() allocates a new block ('entry') to merge
adjacent ranges and then stores it with mas_store_gfp().
When mas_store_gfp() fails, the new 'entry' remains allocated and
is never freed, leaking memory.

Free 'entry' on the failure path; on success continue freeing the
replaced neighbor blocks ('lower', 'upper').

Signed-off-by: Kaushlendra Kumar <kaushlendra.kumar@intel.com>
Link: https://patch.msgid.link/20260105031820.260119-1-kaushlendra.kumar@intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
regmap: maple: Provide lockdep (sub)class for maple tree's internal lock 2024-12-14T19:03:40+00:00 Cristian Ciocaltea cristian.ciocaltea@collabora.com 2024-10-31T16:37:04+00:00 0380da1da737d68b16dd6bd2914e6bb802a11632 [ Upstream commit 1ed9b927e7dd8b8cff13052efe212a8ff72ec51d ] In some cases when using the maple tree register cache, the lockdep validator might complain about invalid deadlocks: [7.131886] Possible interrupt unsafe locking scenario: [7.131890] CPU0 CPU1 [7.131893] ---- ---- [7.131896] lock(&mt->ma_lock); [7.131904] local_irq_disable(); [7.131907] lock(rockchip_drm_vop2:3114:(&vop2_regmap_config)->lock); [7.131916] lock(&mt->ma_lock); [7.131925] <Interrupt> [7.131928] lock(rockchip_drm_vop2:3114:(&vop2_regmap_config)->lock); [7.131936] *** DEADLOCK *** [7.131939] no locks held by swapper/0/0. [7.131944] the shortest dependencies between 2nd lock and 1st lock: [7.131950] -> (&mt->ma_lock){+.+.}-{2:2} { [7.131966] HARDIRQ-ON-W at: [7.131973] lock_acquire+0x200/0x330 [7.131986] _raw_spin_lock+0x50/0x70 [7.131998] regcache_maple_write+0x68/0xe0 [7.132010] regcache_write+0x6c/0x90 [7.132019] _regmap_read+0x19c/0x1d0 [7.132029] _regmap_update_bits+0xc0/0x148 [7.132038] regmap_update_bits_base+0x6c/0xa8 [7.132048] rk8xx_probe+0x22c/0x3d8 [7.132057] rk8xx_spi_probe+0x74/0x88 [7.132065] spi_probe+0xa8/0xe0 [...] [7.132675] } [7.132678] ... key at: [<ffff800082943c20>] __key.0+0x0/0x10 [7.132691] ... acquired at: [7.132695] _raw_spin_lock+0x50/0x70 [7.132704] regcache_maple_write+0x68/0xe0 [7.132714] regcache_write+0x6c/0x90 [7.132724] _regmap_read+0x19c/0x1d0 [7.132732] _regmap_update_bits+0xc0/0x148 [7.132741] regmap_field_update_bits_base+0x74/0xb8 [7.132751] vop2_plane_atomic_update+0x480/0x14d8 [rockchipdrm] [7.132820] drm_atomic_helper_commit_planes+0x1a0/0x320 [drm_kms_helper] [...] [7.135112] -> (rockchip_drm_vop2:3114:(&vop2_regmap_config)->lock){-...}-{2:2} { [7.135130] IN-HARDIRQ-W at: [7.135136] lock_acquire+0x200/0x330 [7.135147] _raw_spin_lock_irqsave+0x6c/0x98 [7.135157] regmap_lock_spinlock+0x20/0x40 [7.135166] regmap_read+0x44/0x90 [7.135175] vop2_isr+0x90/0x290 [rockchipdrm] [7.135225] __handle_irq_event_percpu+0x124/0x2d0 In the example above, the validator seems to get the scope of dependencies wrong, since the regmap instance used in rk8xx-spi driver has nothing to do with the instance from vop2. Improve validation by sharing the regmap's lockdep class with the maple tree's internal lock, while also providing a subclass for the latter. Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com> Link: https://patch.msgid.link/20241031-regmap-maple-lockdep-fix-v2-1-06a3710f3623@collabora.com Signed-off-by: Mark Brown <broonie@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 1ed9b927e7dd8b8cff13052efe212a8ff72ec51d ]

In some cases when using the maple tree register cache, the lockdep
validator might complain about invalid deadlocks:

[7.131886]  Possible interrupt unsafe locking scenario:

[7.131890]        CPU0                    CPU1
[7.131893]        ----                    ----
[7.131896]   lock(&mt->ma_lock);
[7.131904]                                local_irq_disable();
[7.131907]                                lock(rockchip_drm_vop2:3114:(&vop2_regmap_config)->lock);
[7.131916]                                lock(&mt->ma_lock);
[7.131925]   <Interrupt>
[7.131928]     lock(rockchip_drm_vop2:3114:(&vop2_regmap_config)->lock);
[7.131936]
                *** DEADLOCK ***

[7.131939] no locks held by swapper/0/0.
[7.131944]
               the shortest dependencies between 2nd lock and 1st lock:
[7.131950]  -> (&mt->ma_lock){+.+.}-{2:2} {
[7.131966]     HARDIRQ-ON-W at:
[7.131973]                       lock_acquire+0x200/0x330
[7.131986]                       _raw_spin_lock+0x50/0x70
[7.131998]                       regcache_maple_write+0x68/0xe0
[7.132010]                       regcache_write+0x6c/0x90
[7.132019]                       _regmap_read+0x19c/0x1d0
[7.132029]                       _regmap_update_bits+0xc0/0x148
[7.132038]                       regmap_update_bits_base+0x6c/0xa8
[7.132048]                       rk8xx_probe+0x22c/0x3d8
[7.132057]                       rk8xx_spi_probe+0x74/0x88
[7.132065]                       spi_probe+0xa8/0xe0

[...]

[7.132675]   }
[7.132678]   ... key      at: [<ffff800082943c20>] __key.0+0x0/0x10
[7.132691]   ... acquired at:
[7.132695]    _raw_spin_lock+0x50/0x70
[7.132704]    regcache_maple_write+0x68/0xe0
[7.132714]    regcache_write+0x6c/0x90
[7.132724]    _regmap_read+0x19c/0x1d0
[7.132732]    _regmap_update_bits+0xc0/0x148
[7.132741]    regmap_field_update_bits_base+0x74/0xb8
[7.132751]    vop2_plane_atomic_update+0x480/0x14d8 [rockchipdrm]
[7.132820]    drm_atomic_helper_commit_planes+0x1a0/0x320 [drm_kms_helper]

[...]

[7.135112] -> (rockchip_drm_vop2:3114:(&vop2_regmap_config)->lock){-...}-{2:2} {
[7.135130]    IN-HARDIRQ-W at:
[7.135136]                     lock_acquire+0x200/0x330
[7.135147]                     _raw_spin_lock_irqsave+0x6c/0x98
[7.135157]                     regmap_lock_spinlock+0x20/0x40
[7.135166]                     regmap_read+0x44/0x90
[7.135175]                     vop2_isr+0x90/0x290 [rockchipdrm]
[7.135225]                     __handle_irq_event_percpu+0x124/0x2d0

In the example above, the validator seems to get the scope of
dependencies wrong, since the regmap instance used in rk8xx-spi driver
has nothing to do with the instance from vop2.

Improve validation by sharing the regmap's lockdep class with the maple
tree's internal lock, while also providing a subclass for the latter.

Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
Link: https://patch.msgid.link/20241031-regmap-maple-lockdep-fix-v2-1-06a3710f3623@collabora.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
regcache: use map->alloc_flags also for allocating cache 2024-08-28T12:52:29+00:00 Marek Szyprowski m.szyprowski@samsung.com 2024-08-28T12:28:34+00:00 ae0acef3822ed8908e83cd24f337891e6be64eba Commit fd4ebc07b4df ("regmap: Hold the regmap lock when allocating and freeing the cache") introduced a locking around the allocating and freeing a regmap cache, so adjust the memory allocation flags to the ones given in the regmap configuration instead of the hardcoded GFP_KERNEL. This fixes the "BUG: sleeping function called from invalid context" introduced by the mentioned commit. Fixes: fd4ebc07b4df ("regmap: Hold the regmap lock when allocating and freeing the cache") Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com> Link: https://patch.msgid.link/20240828122834.3778031-1-m.szyprowski@samsung.com Signed-off-by: Mark Brown <broonie@kernel.org> 
Commit fd4ebc07b4df ("regmap: Hold the regmap lock when allocating and
freeing the cache") introduced a locking around the allocating and
freeing a regmap cache, so adjust the memory allocation flags to the ones
given in the regmap configuration instead of the hardcoded GFP_KERNEL.

This fixes the "BUG: sleeping function called from invalid context"
introduced by the mentioned commit.

Fixes: fd4ebc07b4df ("regmap: Hold the regmap lock when allocating and freeing the cache")
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://patch.msgid.link/20240828122834.3778031-1-m.szyprowski@samsung.com
Signed-off-by: Mark Brown <broonie@kernel.org>
regmap: maple: work around gcc-14.1 false-positive warning 2024-07-22T12:04:04+00:00 Arnd Bergmann arnd@arndb.de 2024-07-19T10:40:24+00:00 542440fd7b30983cae23e32bd22f69a076ec7ef4 With gcc-14.1, there is a false-postive -Wuninitialized warning in regcache_maple_drop: drivers/base/regmap/regcache-maple.c: In function 'regcache_maple_drop': drivers/base/regmap/regcache-maple.c:113:23: error: 'lower_index' is used uninitialized [-Werror=uninitialized] 113 | unsigned long lower_index, lower_last; | ^~~~~~~~~~~ drivers/base/regmap/regcache-maple.c:113:36: error: 'lower_last' is used uninitialized [-Werror=uninitialized] 113 | unsigned long lower_index, lower_last; | ^~~~~~~~~~ I've created a reduced test case to see if this needs to be reported as a gcc, but it appears that the gcc-14.x branch already has a change that turns this into a more sensible -Wmaybe-uninitialized warning, so I ended up not reporting it so far. The reduced test case also produces a warning for gcc-13 and gcc-12 but I don't see that with the version in the kernel. Link: https://godbolt.org/z/oKbohKqd3 Link: https://lore.kernel.org/all/CAMuHMdWj=FLmkazPbYKPevDrcym2_HDb_U7Mb9YE9ovrP0jJfA@mail.gmail.com/ Signed-off-by: Arnd Bergmann <arnd@arndb.de> Link: https://patch.msgid.link/20240719104030.1382465-1-arnd@kernel.org Signed-off-by: Mark Brown <broonie@kernel.org> 
With gcc-14.1, there is a false-postive -Wuninitialized warning in
regcache_maple_drop:

drivers/base/regmap/regcache-maple.c: In function 'regcache_maple_drop':
drivers/base/regmap/regcache-maple.c:113:23: error: 'lower_index' is used uninitialized [-Werror=uninitialized]
  113 |         unsigned long lower_index, lower_last;
      |                       ^~~~~~~~~~~
drivers/base/regmap/regcache-maple.c:113:36: error: 'lower_last' is used uninitialized [-Werror=uninitialized]
  113 |         unsigned long lower_index, lower_last;
      |                                    ^~~~~~~~~~

I've created a reduced test case to see if this needs to be reported
as a gcc, but it appears that the gcc-14.x branch already has a change
that turns this into a more sensible -Wmaybe-uninitialized warning, so
I ended up not reporting it so far.

The reduced test case also produces a warning for gcc-13 and gcc-12
but I don't see that with the version in the kernel.

Link: https://godbolt.org/z/oKbohKqd3
Link: https://lore.kernel.org/all/CAMuHMdWj=FLmkazPbYKPevDrcym2_HDb_U7Mb9YE9ovrP0jJfA@mail.gmail.com/
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://patch.msgid.link/20240719104030.1382465-1-arnd@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>
regmap: maple: Switch to use kmemdup_array() 2024-06-07T13:28:23+00:00 Andy Shevchenko andriy.shevchenko@linux.intel.com 2024-06-06T16:46:25+00:00 bce843065804f770ac469d32a3d455b9a997b55f Let the kememdup_array() take care about multiplication and possible overflows. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/20240606164717.3031107-5-andriy.shevchenko@linux.intel.com Signed-off-by: Mark Brown <broonie@kernel.org> 
Let the kememdup_array() take care about multiplication and possible
overflows.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240606164717.3031107-5-andriy.shevchenko@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>
regmap: kunit: Add some test cases and a few small 2024-04-09T22:27:14+00:00 Mark Brown broonie@kernel.org 2024-04-09T22:27:14+00:00 8a8317f92770ab70ff39b15de74bdb3a07fdb6cb Merge series from Richard Fitzgerald <rf@opensource.cirrus.com>: This series adds some more test cases, mainly for testing: commit eaa03486d932 ("regmap: maple: Fix uninitialized symbol 'ret' warnings") commit 00bb549d7d63 ("regmap: maple: Fix cache corruption in regcache_maple_drop()") And the pending patch ("regmap: Add regmap_read_bypassed()") There are also a few small improvements to the KUnit implementation. 
Merge series from Richard Fitzgerald <rf@opensource.cirrus.com>:

This series adds some more test cases, mainly for testing:

commit eaa03486d932 ("regmap: maple: Fix uninitialized symbol 'ret' warnings")
commit 00bb549d7d63 ("regmap: maple: Fix cache corruption in regcache_maple_drop()")

And the pending patch ("regmap: Add regmap_read_bypassed()")

There are also a few small improvements to the KUnit implementation.
regmap: maple: Fix uninitialized symbol 'ret' warnings 2024-03-29T16:32:26+00:00 Richard Fitzgerald rf@opensource.cirrus.com 2024-03-29T14:46:30+00:00 eaa03486d932572dfd1c5f64f9dfebe572ad88c0 Fix warnings reported by smatch by initializing local 'ret' variable to 0. drivers/base/regmap/regcache-maple.c:186 regcache_maple_drop() error: uninitialized symbol 'ret'. drivers/base/regmap/regcache-maple.c:290 regcache_maple_sync() error: uninitialized symbol 'ret'. Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com> Fixes: f033c26de5a5 ("regmap: Add maple tree based register cache") Link: https://lore.kernel.org/r/20240329144630.1965159-1-rf@opensource.cirrus.com Signed-off-by: Mark Brown <broonie@kernel.org> 
Fix warnings reported by smatch by initializing local 'ret' variable
to 0.

drivers/base/regmap/regcache-maple.c:186 regcache_maple_drop()
error: uninitialized symbol 'ret'.
drivers/base/regmap/regcache-maple.c:290 regcache_maple_sync()
error: uninitialized symbol 'ret'.

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Fixes: f033c26de5a5 ("regmap: Add maple tree based register cache")
Link: https://lore.kernel.org/r/20240329144630.1965159-1-rf@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>
regmap: maple: Fix cache corruption in regcache_maple_drop() 2024-03-27T15:00:28+00:00 Richard Fitzgerald rf@opensource.cirrus.com 2024-03-27T11:44:06+00:00 00bb549d7d63a21532e76e4a334d7807a54d9f31 When keeping the upper end of a cache block entry, the entry[] array must be indexed by the offset from the base register of the block, i.e. max - mas.index. The code was indexing entry[] by only the register address, leading to an out-of-bounds access that copied some part of the kernel memory over the cache contents. This bug was not detected by the regmap KUnit test because it only tests with a block of registers starting at 0, so mas.index == 0. Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com> Fixes: f033c26de5a5 ("regmap: Add maple tree based register cache") Link: https://msgid.link/r/20240327114406.976986-1-rf@opensource.cirrus.com Signed-off-by: Mark Brown <broonie@kernel.org> 
When keeping the upper end of a cache block entry, the entry[] array
must be indexed by the offset from the base register of the block,
i.e. max - mas.index.

The code was indexing entry[] by only the register address, leading
to an out-of-bounds access that copied some part of the kernel
memory over the cache contents.

This bug was not detected by the regmap KUnit test because it only
tests with a block of registers starting at 0, so mas.index == 0.

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Fixes: f033c26de5a5 ("regmap: Add maple tree based register cache")
Link: https://msgid.link/r/20240327114406.976986-1-rf@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>
regmap: maple: Remove second semicolon 2024-03-25T00:47:58+00:00 Colin Ian King colin.i.king@gmail.com 2024-03-15T08:44:17+00:00 aad6b35290f52639d3601063d33d9621c0948a04 There is a statement with two semicolons. Remove the second one, it is redundant. Signed-off-by: Colin Ian King <colin.i.king@gmail.com> Link: https://msgid.link/r/20240315084417.2427797-1-colin.i.king@gmail.com Signed-off-by: Mark Brown <broonie@kernel.org> 
There is a statement with two semicolons. Remove the second one, it
is redundant.

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Link: https://msgid.link/r/20240315084417.2427797-1-colin.i.king@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>
regmap: maple: Use alloc_flags for memory allocations 2023-07-20T19:37:39+00:00 Guenter Roeck linux@roeck-us.net 2023-07-20T17:20:21+00:00 b0393e1fe40e962574613a5cdc4a470d6c1de023 REGCACHE_MAPLE needs to allocate memory for regmap operations. This results in lockdep splats if used with fast_io since fast_io uses spinlocks for locking. BUG: sleeping function called from invalid context at include/linux/sched/mm.h:306 in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 167, name: kunit_try_catch preempt_count: 1, expected: 0 1 lock held by kunit_try_catch/167: #0: 838e9c10 (regmap_kunit:86:(config)->lock){....}-{2:2}, at: regmap_lock_spinlock+0x14/0x1c irq event stamp: 146 hardirqs last enabled at (145): [<8078bfa8>] crng_make_state+0x1a0/0x294 hardirqs last disabled at (146): [<80c5f62c>] _raw_spin_lock_irqsave+0x7c/0x80 softirqs last enabled at (0): [<80110cc4>] copy_process+0x810/0x216c softirqs last disabled at (0): [<00000000>] 0x0 CPU: 0 PID: 167 Comm: kunit_try_catch Tainted: G N 6.5.0-rc1-00028-gc4be22597a36-dirty #6 Hardware name: Generic DT based system unwind_backtrace from show_stack+0x18/0x1c show_stack from dump_stack_lvl+0x38/0x5c dump_stack_lvl from __might_resched+0x188/0x2d0 __might_resched from __kmem_cache_alloc_node+0x1f4/0x258 __kmem_cache_alloc_node from __kmalloc+0x48/0x170 __kmalloc from regcache_maple_write+0x194/0x248 regcache_maple_write from _regmap_write+0x88/0x140 _regmap_write from regmap_write+0x44/0x68 regmap_write from basic_read_write+0x8c/0x27c basic_read_write from kunit_generic_run_threadfn_adapter+0x1c/0x28 kunit_generic_run_threadfn_adapter from kthread+0xf8/0x120 kthread from ret_from_fork+0x14/0x3c Exception stack(0x881a5fb0 to 0x881a5ff8) 5fa0: 00000000 00000000 00000000 00000000 5fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 5fe0: 00000000 00000000 00000000 00000000 00000013 00000000 Use map->alloc_flags instead of GFP_KERNEL for memory allocations to fix the problem. Fixes: f033c26de5a5 ("regmap: Add maple tree based register cache") Cc: Dan Carpenter <dan.carpenter@linaro.org> Signed-off-by: Guenter Roeck <linux@roeck-us.net> Link: https://lore.kernel.org/r/20230720172021.2617326-1-linux@roeck-us.net Signed-off-by: Mark Brown <broonie@kernel.org> 
REGCACHE_MAPLE needs to allocate memory for regmap operations.
This results in lockdep splats if used with fast_io since fast_io uses
spinlocks for locking.

BUG: sleeping function called from invalid context at include/linux/sched/mm.h:306
in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 167, name: kunit_try_catch
preempt_count: 1, expected: 0
1 lock held by kunit_try_catch/167:
 #0: 838e9c10 (regmap_kunit:86:(config)->lock){....}-{2:2}, at: regmap_lock_spinlock+0x14/0x1c
irq event stamp: 146
hardirqs last  enabled at (145): [<8078bfa8>] crng_make_state+0x1a0/0x294
hardirqs last disabled at (146): [<80c5f62c>] _raw_spin_lock_irqsave+0x7c/0x80
softirqs last  enabled at (0): [<80110cc4>] copy_process+0x810/0x216c
softirqs last disabled at (0): [<00000000>] 0x0
CPU: 0 PID: 167 Comm: kunit_try_catch Tainted: G                 N 6.5.0-rc1-00028-gc4be22597a36-dirty #6
Hardware name: Generic DT based system
 unwind_backtrace from show_stack+0x18/0x1c
 show_stack from dump_stack_lvl+0x38/0x5c
 dump_stack_lvl from __might_resched+0x188/0x2d0
 __might_resched from __kmem_cache_alloc_node+0x1f4/0x258
 __kmem_cache_alloc_node from __kmalloc+0x48/0x170
 __kmalloc from regcache_maple_write+0x194/0x248
 regcache_maple_write from _regmap_write+0x88/0x140
 _regmap_write from regmap_write+0x44/0x68
 regmap_write from basic_read_write+0x8c/0x27c
 basic_read_write from kunit_generic_run_threadfn_adapter+0x1c/0x28
 kunit_generic_run_threadfn_adapter from kthread+0xf8/0x120
 kthread from ret_from_fork+0x14/0x3c
Exception stack(0x881a5fb0 to 0x881a5ff8)
5fa0:                                     00000000 00000000 00000000 00000000
5fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
5fe0: 00000000 00000000 00000000 00000000 00000013 00000000

Use map->alloc_flags instead of GFP_KERNEL for memory allocations to fix
the problem.

Fixes: f033c26de5a5 ("regmap: Add maple tree based register cache")
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20230720172021.2617326-1-linux@roeck-us.net
Signed-off-by: Mark Brown <broonie@kernel.org>