kernel/linux.git/drivers/mailbox/pcc.c, branch v6.12.80

mailbox: pcc: Remove spurious IRQF_ONESHOT usage

2026-03-04T12:21:21+00:00

[ Upstream commit 673327028cd61db68a1e0c708be2e302c082adf9 ] The PCC code currently specifies IRQF_ONESHOT if the interrupt could potentially be shared but doesn't actually use request_threaded_irq() and the interrupt handler does not use IRQ_WAKE_THREAD so IRQF_ONESHOT is never relevant. Since commit aef30c8d569c ("genirq: Warn about using IRQF_ONESHOT without a threaded handler") specifying it has resulted in a WARN_ON(), fix this by removing IRQF_ONESHOT. Reported-by: Aishwarya TCV Signed-off-by: Mark Brown Reviewed-by: Sudeep Holla Signed-off-by: Jassi Brar Signed-off-by: Sasha Levin

mailbox: pcc: don't zero error register

2025-12-06T21:24:56+00:00

[ Upstream commit ff0e4d4c97c94af34cc9cad37b5a5cdbe597a3b0 ] The error status mask for a type 3/4 subspace is used for reading the error status, and the bitwise inverse is used for clearing the error with the intent being to preserve any of the non-error bits. However, we were previously applying the mask to extract the status and then applying the inverse to the result which ended up clearing all bits. Instead, store the inverse mask in the preserve mask and then use that on the original value read from the error status so that only the error is cleared. Fixes: c45ded7e1135 ("mailbox: pcc: Add support for PCCT extended PCC subspaces(type 3/4)") Signed-off-by: Jamie Iles Signed-off-by: Punit Agrawal Signed-off-by: Jassi Brar Signed-off-by: Sasha Levin

mailbox: pcc: Refactor error handling in irq handler into separate function

2025-12-06T21:24:56+00:00

[ Upstream commit 3a675f50415b95f2ae10bfd932e2154ba1a08ee7 ] The existing error handling logic in pcc_mbox_irq() is intermixed with the main flow of the function. The command complete check and the complete complete update/acknowledgment are nicely factored into separate functions. Moves error detection and clearing logic into a separate function called: pcc_mbox_error_check_and_clear() by extracting error-handling logic from pcc_mbox_irq(). This ensures error checking and clearing are handled separately and it improves maintainability by keeping the IRQ handler focused on processing events. Acked-by: Huisong Li Tested-by: Huisong Li Tested-by: Adam Young Signed-off-by: Sudeep Holla Signed-off-by: Jassi Brar Stable-dep-of: ff0e4d4c97c9 ("mailbox: pcc: don't zero error register") Signed-off-by: Sasha Levin

mailbox: pcc: Use acpi_os_ioremap() instead of ioremap()

2025-05-29T09:02:04+00:00

[ Upstream commit d181acea5b864e91f38f5771b8961215ce5017ae ] The Platform Communication Channel (PCC) mailbox driver currently uses ioremap() to map channel shared memory regions. However it is preferred to use acpi_os_ioremap(), which is mapping function specific to EFI/ACPI defined memory regions. It ensures that the correct memory attributes are applied when mapping ACPI-provided regions. While at it, also add checks for handling any errors with the mapping. Acked-by: Huisong Li Tested-by: Huisong Li Tested-by: Adam Young Signed-off-by: Sudeep Holla Signed-off-by: Jassi Brar Signed-off-by: Sasha Levin

mailbox: pcc: Always clear the platform ack interrupt first

2025-05-02T05:59:16+00:00

[ Upstream commit cf1338c0e02880cd235a4590eeb15e2039c873bc ] The PCC mailbox interrupt handler (pcc_mbox_irq()) currently checks for command completion flags and any error status before clearing the interrupt. The below sequence highlights an issue in the handling of PCC mailbox interrupts, specifically when dealing with doorbell notifications and acknowledgment between the OSPM and the platform where type3 and type4 channels are sharing the interrupt. ------------------------------------------------------------------------- | T | Platform Firmware | OSPM/Linux PCC driver | |---|---------------------------------|---------------------------------| | 1 | | Build message in shmem | | 2 | | Ring Type3 chan doorbell | | 3 | Receives the doorbell interrupt | | | 4 | Process the message from OSPM | | | 5 | Build response for the message | | | 6 | Ring Platform ACK interrupt on | | | | Type3 chan to OSPM | Received the interrupt | | 7 | Build Notification in Type4 Chan| | | 8 | | Start processing interrupt in | | | | pcc_mbox_irq() handler | | 9 | | Enter PCC handler for Type4 chan| |10 | | Check command complete cleared | |11 | | Read the notification | |12 | | Clear Platform ACK interrupt | | | No effect from the previous step yet as the Platform ACK | | | interrupt has not yet been triggered for this channel | |13 | Ring Platform ACK interrupt on | | | | Type4 chan to OSPM | | |14 | | Enter PCC handler for Type3 chan| |15 | | Command complete is set. | |16 | | Read the response. | |17 | | Clear Platform ACK interrupt | |18 | | Leave PCC handler for Type3 | |19 | | Leave pcc_mbox_irq() handler | |20 | | Re-enter pcc_mbox_irq() handler | |21 | | Enter PCC handler for Type4 chan| |22 | | Leave PCC handler for Type4 chan| |23 | | Enter PCC handler for Type3 chan| |24 | | Leave PCC handler for Type3 chan| |25 | | Leave pcc_mbox_irq() handler | ------------------------------------------------------------------------- The key issue occurs when OSPM tries to acknowledge platform ack interrupt for a notification which is ready to be read and processed but the interrupt itself is not yet triggered by the platform. This ineffective acknowledgment leads to an issue later in time where the interrupt remains pending as we exit the interrupt handler without clearing the platform ack interrupt as there is no pending response or notification. The interrupt acknowledgment order is incorrect. To resolve this issue, the platform acknowledgment interrupt should always be cleared before processing the interrupt for any notifications or response. Reported-by: Robbie King Reviewed-by: Huisong Li Tested-by: Huisong Li Tested-by: Adam Young Tested-by: Robbie King Signed-off-by: Sudeep Holla Signed-off-by: Jassi Brar Signed-off-by: Sasha Levin

mailbox: pcc: Fix the possible race in updation of chan_in_use flag

2025-05-02T05:59:16+00:00

[ Upstream commit 9779d45c749340ab461d595c1a4a664cb28f3007 ] The function mbox_chan_received_data() calls the Rx callback of the mailbox client driver. The callback might set chan_in_use flag from pcc_send_data(). This flag's status determines whether the PCC channel is in use. However, there is a potential race condition where chan_in_use is updated incorrectly due to concurrency between the interrupt handler (pcc_mbox_irq()) and the command sender(pcc_send_data()). The 'chan_in_use' flag of a channel is set to true after sending a command. And the flag of the new command may be cleared erroneous by the interrupt handler afer mbox_chan_received_data() returns, As a result, the interrupt being level triggered can't be cleared in pcc_mbox_irq() and it will be disabled after the number of handled times exceeds the specified value. The error log is as follows: | kunpeng_hccs HISI04B2:00: PCC command executed timeout! | kunpeng_hccs HISI04B2:00: get port link status info failed, ret = -110 | irq 13: nobody cared (try booting with the "irqpoll" option) | Call trace: | dump_backtrace+0x0/0x210 | show_stack+0x1c/0x2c | dump_stack+0xec/0x130 | __report_bad_irq+0x50/0x190 | note_interrupt+0x1e4/0x260 | handle_irq_event+0x144/0x17c | handle_fasteoi_irq+0xd0/0x240 | __handle_domain_irq+0x80/0xf0 | gic_handle_irq+0x74/0x2d0 | el1_irq+0xbc/0x140 | mnt_clone_write+0x0/0x70 | file_update_time+0xcc/0x160 | fault_dirty_shared_page+0xe8/0x150 | do_shared_fault+0x80/0x1d0 | do_fault+0x118/0x1a4 | handle_pte_fault+0x154/0x230 | __handle_mm_fault+0x1ac/0x390 | handle_mm_fault+0xf0/0x250 | do_page_fault+0x184/0x454 | do_translation_fault+0xac/0xd4 | do_mem_abort+0x44/0xb4 | el0_da+0x40/0x74 | el0_sync_handler+0x60/0xb4 | el0_sync+0x168/0x180 | handlers: | pcc_mbox_irq | Disabling IRQ #13 To solve this issue, pcc_mbox_irq() must clear 'chan_in_use' flag before the call to mbox_chan_received_data(). Tested-by: Adam Young Tested-by: Robbie King Signed-off-by: Huisong Li (sudeep.holla: Minor updates to the subject, commit message and comment) Signed-off-by: Sudeep Holla Signed-off-by: Jassi Brar Signed-off-by: Sasha Levin

mailbox: pcc: Check before sending MCTP PCC response ACK

2024-12-14T19:04:03+00:00

[ Upstream commit 7f9e19f207be0c534d517d65e01417ba968cdd34 ] 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 Signed-off-by: Sasha Levin

mailbox: pcc: Support shared interrupt for multiple subspaces

2023-09-11T09:31:17+00:00

If the platform acknowledge interrupt is level triggered, then it can be shared by multiple subspaces provided each one has a unique platform interrupt ack preserve and ack set masks. If it can be shared, then we can request the irq with IRQF_SHARED and IRQF_ONESHOT flags. The first one indicating it can be shared and the latter one to keep the interrupt disabled until the hardirq handler finished. Further, since there is no way to detect if the interrupt is for a given channel as the interrupt ack preserve and ack set masks are for clearing the interrupt and not for reading the status(in case Irq Ack register may be write-only on some platforms), we need a way to identify if the given channel is in use and expecting the interrupt. PCC type0, type1 and type5 do not support shared level triggered interrupt. The methods of determining whether a given channel for remaining types should respond to an interrupt are as follows: - type2: Whether the interrupt belongs to a given channel is only determined by the status field in Generic Communications Channel Shared Memory Region, which is done in rx_callback of PCC client. - type3: This channel checks chan_in_use flag first and then checks the command complete bit(value '1' indicates that the command has been completed). - type4: Platform ensure that the default value of the command complete bit corresponding to the type4 channel is '1'. This command complete bit is '0' when receive a platform notification. The new field, 'chan_in_use' is used by the type only support the communication from OSPM to Platform (like type3) and should be completely ignored by other types so as to avoid too many type unnecessary checks in IRQ handler. Signed-off-by: Huisong Li Reviewed-by: Hanjun Guo Link: https://lore.kernel.org/r/20230801063827.25336-3-lihuisong@huawei.com Signed-off-by: Sudeep Holla

mailbox: pcc: Add support for platform notification handling

2023-09-11T09:31:17+00:00

Currently, PCC driver doesn't support the processing of platform notification for type 4 PCC subspaces. According to ACPI specification, if platform sends a notification to OSPM, it must clear the command complete bit and trigger platform interrupt. OSPM needs to check whether the command complete bit is cleared, clear platform interrupt, process command, and then set the command complete and ring doorbell to the Platform. Let us stash the value of the pcc type and use the same while processing the interrupt of the channel. We also need to set the command complete bit and ring doorbell in the interrupt handler for the type 4 channel to complete the communication flow after processing the notification from the Platform. Signed-off-by: Huisong Li Reviewed-by: Hanjun Guo Link: https://lore.kernel.org/r/20230801063827.25336-2-lihuisong@huawei.com Signed-off-by: Sudeep Holla

mailbox: pcc: Use mbox_bind_client

2023-04-18T16:48:56+00:00

Use generic mbox_bind_client() to bind omap mailbox channel to a client. mbox_bind_client is identical to the replaced lines, except that it: - Does the operation under con_mutex which prevents possible races in removal path - Sets TXDONE_BY_ACK if pcc uses TXDONE_BY_POLL and the client knows when tx is done. TXDONE_BY_ACK is already set if there's no interrupt, so this is not applicable. - Calls chan->mbox->ops->startup. This is usecase for requesting irq: move the devm_request_irq into the startup callback and unregister it in the shutdown path. Tested-by: Sudeep Holla Signed-off-by: Elliot Berman Signed-off-by: Jassi Brar