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Explain when the MBOX_PSP return codes are send and which behaviour
is invoked by the PSP when seeing such return codes.

Change-Id: Ibe7ceb5d7cd025f3b3ab0c9167d23f6eb664c165
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/88511
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Alicja Michalska <ahplka19@gmail.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
This commit is contained in:
Patrick Rudolph 2025-07-21 11:01:15 +02:00 • committed by Matt DeVillier
commit 02980f0ea6
2 changed files with 24 additions and 4 deletions
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20
src/soc/amd/common/block/psp/psp_def.h
View file

@ -143,10 +143,22 @@ enum mbox_p2c_status {
MBOX_PSP_SUCCESS = 0x00,
MBOX_PSP_INVALID_PARAMETER = 0x01,
MBOX_PSP_CRC_ERROR = 0x02,
MBOX_PSP_COMMAND_PROCESS_ERROR = 0x04,
MBOX_PSP_UNSUPPORTED = 0x08,
MBOX_PSP_SPI_BUSY_ASYNC = 0x0a,
MBOX_PSP_SPI_BUSY = 0x0b,
/*
* Send to PSP when the requested SPI command in the psp_smi_handler()
* handler failed due to an unknown error. The PSP usually doesn't like
* seeing this return code and will stop operating.
*/
MBOX_PSP_COMMAND_PROCESS_ERROR = 0x04,
MBOX_PSP_UNSUPPORTED = 0x08,
MBOX_PSP_SPI_BUSY_ASYNC = 0x0a,
/*
* Send to PSP when the requested SPI command in the psp_smi_handler()
* handler cannot be executed right away. This can happen when the SPI
* flash is busy or the SPI controller is busy or being used by ring 0.
*
* The PSP will raise an SMI later again.
*/
MBOX_PSP_SPI_BUSY = 0x0b,
};
uintptr_t get_psp_mmio_base(void);

8
src/soc/amd/common/block/psp/psp_smi_flash.c
View file

@ -92,6 +92,14 @@ static enum mbox_p2c_status find_psp_spi_flash_device_region(uint64_t target_nv_
return MBOX_PSP_SUCCESS;
}
/*
* Returns true when the SPI flash is busy, the SPI controller is busy or the SPI
* MMIO register access is blocked by ring0. When the SPI flash is busy all
* operations, including reading, would fail.
* Thus even memory mapped structures like FMAP would not be accessible
* from memory mapped SPI flash (ROM2/ROM3). Caller must return MBOX_PSP_SPI_BUSY
* to PSP when this function returns true.
*/
static bool spi_controller_busy(void)
{
bool busy;