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hw/ssi/pnv_spi: Put a limit to RDR match failures

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There is a possibility that SPI controller can get into loop due to indefinite
RDR match failures. Hence put a limit to failures and stop the sequencer.

Signed-off-by: Chalapathi V <chalapathi.v@linux.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Message-ID: <20250303141328.23991-5-chalapathi.v@linux.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
This commit is contained in:
Chalapathi V 2025-03-03 08:13:28 -06:00 • committed by Nicholas Piggin
parent 7192d7b7fe
commit a613b9d321
2 changed files with 11 additions and 0 deletions
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10
hw/ssi/pnv_spi.c
View file

@ -20,6 +20,7 @@
#define PNV_SPI_OPCODE_LO_NIBBLE(x) (x & 0x0F)
#define PNV_SPI_MASKED_OPCODE(x) (x & 0xF0)
#define PNV_SPI_FIFO_SIZE 16
#define RDR_MATCH_FAILURE_LIMIT 16
/*
* Macro from include/hw/ppc/fdt.h
@ -872,18 +873,27 @@ static void operation_sequencer(PnvSpi *s)
rdr_matched = does_rdr_match(s);
if (rdr_matched) {
trace_pnv_spi_RDR_match("success");
s->fail_count = 0;
/* A match occurred, increment the sequencer index. */
seq_index++;
s->status = SETFIELD(SPI_STS_SEQ_FSM, s->status,
SEQ_STATE_INDEX_INCREMENT);
} else {
trace_pnv_spi_RDR_match("failed");
s->fail_count++;
/*
* Branch the sequencer to the index coded into the op
* code.
*/
seq_index = PNV_SPI_OPCODE_LO_NIBBLE(opcode);
}
if (s->fail_count >= RDR_MATCH_FAILURE_LIMIT) {
qemu_log_mask(LOG_GUEST_ERROR, "pnv_spi: RDR match failure"
" limit crossed %d times hence requesting "
"sequencer to stop.\n",
RDR_MATCH_FAILURE_LIMIT);
stop = true;
}
/*
* Regardless of where the branch ended up we want the
* sequencer to continue shifting so we have to clear

1
include/hw/ssi/pnv_spi.h
View file

@ -40,6 +40,7 @@ typedef struct PnvSpi {
MemoryRegion xscom_spic_regs;
Fifo8 tx_fifo;
Fifo8 rx_fifo;
uint8_t fail_count; /* RDR Match failure counter */
/* SPI object number */
uint32_t spic_num;
uint32_t chip_id;