firmware: samsung: acpm: Add devm_acpm_get_by_phandle helper

Introduce devm_acpm_get_by_phandle() to standardize how consumer
drivers acquire a handle to the ACPM IPC interface. Enforce the
use of t

firmware: samsung: acpm: Add devm_acpm_get_by_phandle helper

Introduce devm_acpm_get_by_phandle() to standardize how consumer
drivers acquire a handle to the ACPM IPC interface. Enforce the
use of the "samsung,acpm-ipc" property name across the SoC and
simplify the boilerplate code in client drivers.

The first consumer of this helper is the Exynos ACPM Thermal Management
Unit (TMU) driver. The TMU utilizes a hybrid management approach: direct
register access from the Application Processor (AP) is restricted to the
interrupt pending (INTPEND) registers for event identification.
High-level functional tasks, such as sensor initialization, threshold
programming, and temperature reads, are delegated to the ACPM firmware
via this IPC interface.

Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Reviewed-by: Peter Griffin <peter.griffin@linaro.org>
Link: https://patch.msgid.link/20260515-acpm-tmu-helpers-v2-6-8ca011d5a965@linaro.org
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

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firmware: samsung: acpm: Add TMU protocol support

The Thermal Management Unit (TMU) on the Google GS101 SoC is managed
through a hybrid model shared between the kernel and the Alive Clock
and Power

firmware: samsung: acpm: Add TMU protocol support

The Thermal Management Unit (TMU) on the Google GS101 SoC is managed
through a hybrid model shared between the kernel and the Alive Clock
and Power Manager (ACPM) firmware.

Add the protocol helpers required to communicate with the ACPM for
thermal operations, including initialization, threshold configuration,
temperature reading, and system suspend/resume handshakes.

Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Reviewed-by: Peter Griffin <peter.griffin@linaro.org>
Link: https://patch.msgid.link/20260515-acpm-tmu-helpers-v2-5-8ca011d5a965@linaro.org
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

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firmware: samsung: acpm: Make acpm_ops const and access via pointer

Replace the embedded `struct acpm_ops` inside `struct acpm_handle` with
a pointer to a `const struct acpm_ops`.

Previously, the o

firmware: samsung: acpm: Make acpm_ops const and access via pointer

Replace the embedded `struct acpm_ops` inside `struct acpm_handle` with
a pointer to a `const struct acpm_ops`.

Previously, the operations structure was embedded directly within the
handle and populated dynamically at runtime via `acpm_setup_ops()`.
This resulted in mutable function pointers and unnecessary per-instance
memory overhead.

By defining `exynos_acpm_driver_ops` statically as a `const` structure,
the function pointers are now safely housed in the read-only `.rodata`
section. This improves security by preventing function pointer
overwrites, saves memory, and slightly reduces initialization overhead
in `acpm_probe()`.

Consequently, update all consumer drivers (clk, mfd) to access the
operations via the new pointer indirection (`->ops->`). Finally, fix
the previously empty kernel-doc description for the ops member to
reflect its new pointer nature.

Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Reviewed-by: Peter Griffin <peter.griffin@linaro.org>
Link: https://patch.msgid.link/20260515-acpm-tmu-helpers-v2-4-8ca011d5a965@linaro.org
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

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firmware: samsung: acpm: Drop redundant _ops suffix in acpm_ops members

Rename the `dvfs_ops` and `pmic_ops` members of `struct acpm_ops` to
`dvfs` and `pmic` respectively.

Since these members are

firmware: samsung: acpm: Drop redundant _ops suffix in acpm_ops members

Rename the `dvfs_ops` and `pmic_ops` members of `struct acpm_ops` to
`dvfs` and `pmic` respectively.

Since these members are housed within the `acpm_ops` structure and
utilize the `acpm_*_ops` types, the `_ops` suffix on the variable names
creates unnecessary redundancy (e.g., `handle.ops.dvfs_ops`).

This cleanup removes the stuttering, leading to cleaner consumer code.

Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Reviewed-by: Peter Griffin <peter.griffin@linaro.org>
Acked-by: Lee Jones <lee@kernel.org>
Link: https://lore.kernel.org/linux-samsung-soc/CADrjBPqzKpcd9vuCmNUptCUPyPpPbHcc19-7kN-1c0RpW1e5DQ@mail.gmail.com/T/#mcce154a7e0c6cd1ca6cd5a1e37541ed7a85a84d4 [1]
Link: https://patch.msgid.link/20260515-acpm-tmu-helpers-v2-3-8ca011d5a965@linaro.org
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

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firmware: samsung: acpm: Annotate rx_data->cmd with __counted_by_ptr

Rename the `n_cmd` member of `struct acpm_rx_data` to `cmdcnt` to
maintain consistent nomenclature across the driver (aligning wi

firmware: samsung: acpm: Annotate rx_data->cmd with __counted_by_ptr

Rename the `n_cmd` member of `struct acpm_rx_data` to `cmdcnt` to
maintain consistent nomenclature across the driver (aligning with
`txcnt`, `rxcnt`, and transfer helpers).

With the member renamed, annotate the dynamically allocated `cmd`
pointer with the `__counted_by_ptr(cmdcnt)` macro to improve runtime
bounds checking.

Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Reviewed-by: Peter Griffin <peter.griffin@linaro.org>
Link: https://patch.msgid.link/20260515-acpm-tmu-helpers-v2-2-8ca011d5a965@linaro.org
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

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firmware: samsung: acpm: Consolidate transfer initialization helper

Both the DVFS and PMIC ACPM sub-drivers implement similar local helper
functions (acpm_dvfs_set_xfer and acpm_pmic_set_xfer) to in

firmware: samsung: acpm: Consolidate transfer initialization helper

Both the DVFS and PMIC ACPM sub-drivers implement similar local helper
functions (acpm_dvfs_set_xfer and acpm_pmic_set_xfer) to initialize the
acpm_xfer structure before sending an IPC message.

Move this logic into a single centralized helper, acpm_set_xfer(),
in the core ACPM driver to reduce boilerplate, eliminate code
duplication, and prepare for the upcoming ACPM TMU helper sub-driver
which will also utilize this method.

Note that there is no change in underlying functionality. While the old
acpm_pmic_set_xfer() unconditionally assigned the RX buffer parameters
(xfer->rxd and xfer->rxcnt), the new unified helper introduces a
'response' boolean. All updated PMIC call sites now explicitly pass
'true' for this argument. This ensures the unified helper takes the
'if (response)' branch, performing the exact same assignments and
preserving the original PMIC behavior.

Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Reviewed-by: Peter Griffin <peter.griffin@linaro.org>
Link: https://patch.msgid.link/20260515-acpm-tmu-helpers-v2-1-8ca011d5a965@linaro.org
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

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firmware: samsung: acpm: Fix infinite loop on sequence number exhaustion

Sashiko identified a possible infinite loop [1].

ACPM IPC sequence numbers are tracked via a 64-bit bitmap. Previously,
acpm

firmware: samsung: acpm: Fix infinite loop on sequence number exhaustion

Sashiko identified a possible infinite loop [1].

ACPM IPC sequence numbers are tracked via a 64-bit bitmap. Previously,
acpm_prepare_xfer() used a do...while loop to search for a free
sequence number.

If all 63 available sequence numbers are leaked due to transient
hardware timeouts or mailbox failures, the bitmap becomes full.
The next call to acpm_prepare_xfer() would enter an infinite loop.

Fix this by utilizing the kernel's optimized bitmap search functions
(find_next_zero_bit / find_first_zero_bit). If the pool is completely
exhausted, log the failure and return -EBUSY to allow the kernel to
fail gracefully instead of hanging.

Furthermore, drop the allocation loop entirely. Because
acpm_prepare_xfer() is strictly called under the 'tx_lock' mutex,
sequence number allocations are perfectly serialized. If
find_next_zero_bit() locates a free bit, a single
test_and_set_bit_lock() is mathematically guaranteed to succeed.

To enforce this locking invariant, wrap the allocation in a
WARN_ON_ONCE. If the atomic set fails, it indicates the driver's
mutex serialization is fundamentally broken. The warning generates a
stack trace for debugging, while returning -EIO immediately aborts the
transfer to prevent silent payload corruption.

Cc: stable@vger.kernel.org
Fixes: a88927b534ba ("firmware: add Exynos ACPM protocol driver")
Closes: https://sashiko.dev/#/patchset/20260420-acpm-tmu-v3-0-3dc8e93f0b26%40linaro.org [1]
Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Link: https://patch.msgid.link/20260505-acpm-fixes-sashiko-reports-v5-7-43b5ee7f1674@linaro.org
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

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firmware: samsung: acpm: Fix missing LKMM barriers in sequence allocator

Sashiko identified memory ordering races in [1].

The ACPM driver uses a globally shared 'bitmap_seqnum' to track
available s

firmware: samsung: acpm: Fix missing LKMM barriers in sequence allocator

Sashiko identified memory ordering races in [1].

The ACPM driver uses a globally shared 'bitmap_seqnum' to track
available sequence numbers. Even though threads now strictly free their
own sequence numbers, the allocation and freeing of these bits across
concurrent threads are effectively lockless operations and require
explicit LKMM memory barriers.

Previously, the driver used plain bitwise operators (test_bit, set_bit,
clear_bit), which lack ordering guarantees. This creates two race
conditions on weakly ordered architectures like ARM64:

1. Polling Release Violation: The polling thread copies its payload and
calls clear_bit(). Without a release barrier, the CPU can reorder
the memory operations, making the cleared bit globally visible
before the payload reads have fully completed.
2. TX Acquire Violation: The TX thread loops on test_bit(), calls
set_bit(), and then wipes the payload buffer via memset(). Without
an acquire barrier, the CPU can speculatively execute the memset()
before the bit is safely and formally claimed.

If these reorderings overlap, a new TX thread can claim the sequence
number and overwrite the buffer while the original polling thread is
still actively reading from it.

Fix this by upgrading the bitwise operators. Wrap the TX allocation in
test_and_set_bit_lock() to establish formal LKMM Acquire semantics, and
pair it with clear_bit_unlock() in the polling path to enforce Release
semantics.

Cc: stable@vger.kernel.org
Fixes: a88927b534ba ("firmware: add Exynos ACPM protocol driver")
Closes: https://sashiko.dev/#/patchset/20260423-acpm-fixes-sashiko-reports-v1-0-2217b790925e%40linaro.org [1]
Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Link: https://patch.msgid.link/20260505-acpm-fixes-sashiko-reports-v5-6-43b5ee7f1674@linaro.org
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

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firmware: samsung: acpm: Fix false timeouts and Use-After-Free in polling

Sashiko identified severe races in the polling state machine [1].

In the ACPM driver's polling mode, threads waited for res

firmware: samsung: acpm: Fix false timeouts and Use-After-Free in polling

Sashiko identified severe races in the polling state machine [1].

In the ACPM driver's polling mode, threads waited for responses by
monitoring the globally shared 'bitmap_seqnum'. This caused false
timeouts because if a thread processed its response and freed the
sequence number, a concurrent TX thread could immediately reallocate
it before the polling thread woke up.

Additionally, the driver suffered from a cross-thread Use-After-Free
(UAF) preemption race. Previously, acpm_get_rx() cleared the sequence
number of whichever RX message it drained from the hardware queue. This
meant Thread A could globally free Thread B's sequence slot while
Thread B was asleep. A new Thread C could then steal the slot,
overwrite the buffer, and leave Thread B to wake up to corrupted state
or a timeout.

Fix this by rewriting the polling state machine:
1. Decouple polling from the global allocator by introducing a per-slot
'completed' flag, synchronized via smp_store_release() and
smp_load_acquire().
2. Strip acpm_get_saved_rx() out of acpm_get_rx() to make it a pure
queue-draining function. Introduce a 'native_match' boolean argument
which evaluates to true only if the thread natively processed its
own sequence number during the call. This explicitly informs the
polling loop whether it must retrieve its payload from the
cross-thread cache.
3. Centralize the cache fallback and sequence number free (clear_bit)
inside the polling loop. Crucially, the free operation now strictly
targets the thread's own TX sequence number (xfer->txd[0]), rather
than the drained RX sequence number. This enforces strict ownership:
a thread only ever frees its own allocated sequence slot, and only
at the exact moment it completes its poll, eliminating the UAF
window.

Furthermore, explicitly guard the 'native_match' assignment with an
if (rx_seqnum == tx_seqnum) check, even for zero-length (no payload)
responses. While an unguarded assignment wouldn't crash (because the
cache fallback acpm_get_saved_rx() safely returns early on zero-length
transfers) doing so would "lie" to the state machine. If a thread
drained the queue and found another thread's zero-length message,
setting native_match = true would falsely convince the polling loop
that it natively handled its own response. Maintaining a rigorous state
machine requires that native_match is only set when a thread explicitly
processes its own sequence number.

Cc: stable@vger.kernel.org
Fixes: a88927b534ba ("firmware: add Exynos ACPM protocol driver")
Closes: https://sashiko.dev/#/patchset/20260429-acpm-fixes-sashiko-reports-v3-0-47cf74ab09ad%40linaro.org [1]
Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Link: https://patch.msgid.link/20260505-acpm-fixes-sashiko-reports-v5-5-43b5ee7f1674@linaro.org
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

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firmware: samsung: acpm: Fix mailbox channel leak on probe error

Sashiko identified the leak at [1].

The ACPM driver allocates hardware mailbox channels using
`mbox_request_channel()` during `acpm_

firmware: samsung: acpm: Fix mailbox channel leak on probe error

Sashiko identified the leak at [1].

The ACPM driver allocates hardware mailbox channels using
`mbox_request_channel()` during `acpm_channels_init()`. However, the
driver lacked a `.remove` callback and did not free these channels on
subsequent error paths inside `acpm_probe()`.

Additionally, if `acpm_achan_alloc_cmds()` failed during the channel
initialization loop, the function returned immediately, bypassing the
manual cleanup and permanently leaking any channels successfully
requested in previous loop iterations.

Fix this by modifying `acpm_free_mbox_chans()` to match the `devres`
action signature and registering it via `devm_add_action_or_reset()`.

Cc: stable@vger.kernel.org
Fixes: a88927b534ba ("firmware: add Exynos ACPM protocol driver")
Closes: https://sashiko.dev/#/patchset/20260420-acpm-tmu-v3-0-3dc8e93f0b26%40linaro.org [1]
Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Link: https://patch.msgid.link/20260505-acpm-fixes-sashiko-reports-v5-2-43b5ee7f1674@linaro.org
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

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firmware: samsung: acpm: Fix cross-thread RX length corruption

Sashiko identified a cross-thread RX length corruption bug when
reviewing the thermal addition to ACPM [1].

When multiple threads conc

firmware: samsung: acpm: Fix cross-thread RX length corruption

Sashiko identified a cross-thread RX length corruption bug when
reviewing the thermal addition to ACPM [1].

When multiple threads concurrently send IPC requests, the ACPM polling
mechanism can encounter responses belonging to other threads. To drain
the queue, the driver saves these concurrent responses into an internal
cache (`rx_data->cmd`) to be retrieved later by the owning thread.

Previously, the driver incorrectly used `xfer->rxcnt` (the expected
receive length of the *current* polling thread) when copying data for
*other* threads into this cache. If the threads expected responses of
different lengths, this resulted in buffer underflows (leading to reads
of uninitialized memory) or potential buffer overflows.

Fix this by replacing the boolean `response` flag in
`struct acpm_rx_data` with `rxcnt`, caching the exact expected receive
length for each specific transaction during transfer preparation. Use
this cached length when saving concurrent responses.

Consequently, ensure that `xfer->rxcnt` is explicitly zeroed in driver
helpers (e.g., `acpm_dvfs_set_xfer`) for fire-and-forget messages to
prevent uninitialized stack garbage from being interpreted as a massive
expected receive length.

Cc: stable@vger.kernel.org
Fixes: a88927b534ba ("firmware: add Exynos ACPM protocol driver")
Closes: https://sashiko.dev/#/patchset/20260420-acpm-tmu-v3-0-3dc8e93f0b26%40linaro.org [1]
Reported-by: Titouan Ameline de Cadeville <titouan.ameline@gmail.com>
Closes: https://lore.kernel.org/r/20260426210255.73674-1-titouan.ameline@gmail.com/
Signed-off-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Link: https://patch.msgid.link/20260505-acpm-fixes-sashiko-reports-v5-1-43b5ee7f1674@linaro.org
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>

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