kernel/linux.git/include/acpi/pcc.h, branch v6.19.11

Revert "mailbox/pcc: support mailbox management of the shared buffer"

2026-02-26T23:01:19+00:00

[ Upstream commit f82c3e62b6b8c31d8c56415bf38658f306fda4cb ] This reverts commit 5378bdf6a611a32500fccf13d14156f219bb0c85. Commit 5378bdf6a611 ("mailbox/pcc: support mailbox management of the shared buffer") attempted to introduce generic helpers for managing the PCC shared memory, but it largely duplicates functionality already provided by the mailbox core and leaves gaps: 1. TX preparation: The mailbox framework already supports this via ->tx_prepare callback for mailbox clients. The patch adds pcc_write_to_buffer() and expects clients to toggle pchan->chan.manage_writes, but no drivers set manage_writes, so pcc_write_to_buffer() has no users. 2. RX handling: Data reception is already delivered through mbox_chan_received_data() and client ->rx_callback. The patch adds an optional pchan->chan.rx_alloc, which again has no users and duplicates the existing path. 3. Completion handling: While adding last_tx_done is directionally useful, the implementation only covers Type 3/4 and fails to handle the absence of a command_complete register, so it is incomplete for other types. Given the duplication and incomplete coverage, revert this change. Any new requirements should be addressed in focused follow-ups rather than bundling multiple behavioral changes together. Fixes: 5378bdf6a611 ("mailbox/pcc: support mailbox management of the shared buffer") Signed-off-by: Sudeep Holla Signed-off-by: Jassi Brar Signed-off-by: Sasha Levin

mailbox/pcc: support mailbox management of the shared buffer

2025-08-08T04:49:56+00:00

Define a new, optional, callback that allows the driver to specify how the return data buffer is allocated. If that callback is set, mailbox/pcc.c is now responsible for reading from and writing to the PCC shared buffer. This also allows for proper checks of the Commnand complete flag between the PCC sender and receiver. For Type 4 channels, initialize the command complete flag prior to accepting messages. Since the mailbox does not know what memory allocation scheme to use for response messages, the client now has an optional callback that allows it to allocate the buffer for a response message. When an outbound message is written to the buffer, the mailbox checks for the flag indicating the client wants an tx complete notification via IRQ. Upon receipt of the interrupt It will pair it with the outgoing message. The expected use is to free the kernel memory buffer for the previous outgoing message. Signed-off-by: Adam Young Signed-off-by: Jassi Brar

mailbox: pcc: Always map the shared memory communication address

2025-03-27T01:58:26+00:00

Currently the shared memory communication address was mapped by the mailbox client drivers leading to all sorts of inconsistencies. It also has resulted in the inconsistent attributes used while mapping the shared memory regions. In order to remove/eliminate any issues, let us ensures the shared memory address is always mapped and unmapped when the PCC channels are requested and release. We need to map them as the ACPI PCCT associates these shared memory with each channel subspace and may need use the status or the flags in the headers of those shared memory communication address regions to manage the transport/channel. Note, until all the drivers using PCC start using this mapped shmem, there might be double mapping of the shared memory address. This shouldn't have any impact on existing mbox client drivers. Since there are no users of pcc_chan_ioremap() and also it is mapped by default, we can stop exporting it and merge the functionality into pcc_mbox_request_channel(). Acked-by: Huisong Li Tested-by: Huisong Li Tested-by: Adam Young Signed-off-by: Sudeep Holla Signed-off-by: Jassi Brar

mailbox: pcc: Drop unnecessary endianness conversion of pcc_hdr.flags

2025-03-27T01:58:25+00:00

The Sparse static checker flags a type mismatch warning related to endianness conversion: | warning: incorrect type in argument 1 (different base types) | expected restricted __le32 const [usertype] *p | got unsigned int * This is because an explicit endianness conversion (le32_to_cpu()) was applied unnecessarily to a pcc_hdr.flags field that is already in little-endian format. The PCC driver is only enabled on little-endian kernels due to its dependency on ACPI and EFI, making the explicit conversion unnecessary. The redundant conversion occurs in pcc_chan_check_and_ack() for the pcc_hdr.flags field. Drop this unnecessary endianness conversion of pcc_hdr.flags. Also drop the redundant PCC_ACK_FLAG_MASK definition and use the more appropriate and already defined PCC_CMD_COMPLETION_NOTIFY. Acked-by: Huisong Li Tested-by: Adam Young Signed-off-by: Sudeep Holla Signed-off-by: Jassi Brar

mailbox: pcc: Check before sending MCTP PCC response ACK

2024-11-24T19:20:40+00:00

Type 4 PCC channels have an option to send back a response to the platform when they are done processing the request. The flag to indicate whether or not to respond is inside the message body, and thus is not available to the pcc mailbox. If the flag is not set, still set command completion bit after processing message. In order to read the flag, this patch maps the shared buffer to virtual memory. To avoid duplication of mapping the shared buffer is then made available to be used by the driver that uses the mailbox. Signed-off-by: Adam Young Cc: Sudeep Holla Signed-off-by: Jassi Brar

ACPI: PCC: Add PCC shared memory region command and status bitfields

2023-09-28T14:48:48+00:00

Define the common macros to use when referring to various bitfields in the PCC generic communications channel command and status fields. Currently different drivers that need to use these bitfields have defined these locally. This common macro is intended to consolidate and replace those. Cc: "Rafael J. Wysocki" Link: https://lore.kernel.org/r/20230927-pcc_defines-v2-1-0b8ffeaef2e5@arm.com Signed-off-by: Sudeep Holla

mailbox: pcc: Use PCC mailbox channel pointer instead of standard

2021-10-30T03:46:38+00:00

Now that we have all the shared memory region information populated in the pcc_mbox_chan, let us propagate the pointer to the same as the return value to pcc_mbox_request channel. This eliminates the need for the individual users of PCC mailbox to parse the PCCT subspace entries and fetch the shmem information. This also eliminates the need for PCC mailbox controller to set con_priv to PCCT subspace entries. This is required as con_priv is private to the controller driver to attach private data associated with the channel and not meant to be used by the mailbox client/users. Let us convert all the users of pcc_mbox_{request,free}_channel to use new interface. Cc: Jean Delvare Signed-off-by: Sudeep Holla Acked-by: Wolfram Sang Acked-by: Guenter Roeck Signed-off-by: Jassi Brar

mailbox: pcc: Add pcc_mbox_chan structure to hold shared memory region info

2021-10-30T03:46:38+00:00

Currently PCC mailbox controller sets con_priv in each channel to hold the pointer to pcct subspace entry it corresponds to. The mailbox user will then fetch this pointer from the channel descriptor they get when they request for the channel. Using that pointer they then parse the pcct entry again to fetch all the information about shared memory region. In order to remove individual users of PCC mailbox parsing the PCCT subspace entries to fetch same information, let us consolidate the same in pcc mailbox controller by parsing all the shared memory region information into a structure that can also hold the mbox_chan pointer it represent. This can then be used as main PCC mailbox channel pointer that we can return as part of pcc_mbox_request_channel instead of standard mailbox channel pointer. Reviewed-by: Cristian Marussi Signed-off-by: Sudeep Holla Signed-off-by: Jassi Brar

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 441

2019-06-05T15:37:17+00:00

Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license as published by the free software foundation version 2 of the license extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 315 file(s). Signed-off-by: Thomas Gleixner Reviewed-by: Allison Randal Reviewed-by: Armijn Hemel Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190531190115.503150771@linutronix.de Signed-off-by: Greg Kroah-Hartman

mailbox: PCC: Move the MAX_PCC_SUBSPACES definition to header file

2017-11-08T23:39:53+00:00

Move the MAX_PCC_SUBSPACES definition to acpi/pcc.h file in preparation to add subspace ID support for cppc_acpi driver. Signed-off-by: George Cherian Reviewed-by: Prashanth Prakash Signed-off-by: Rafael J. Wysocki