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sb/intel/common/spi: Fix I/O alignment 

On ICH9 the SPI control register is not naturally aligned
and a word write might be split into smaller naturally aligned
I/O transactions.

As the first byte starts a new SPI transfer, replace the existing
word write with two byte writes and write the second byte first.

This is required for platforms that do not support unaligned
word I/O instructions and would start a SPI transfer while the
second byte hasn't reached the control register yet.

TEST: Virtual SPI controller on qemu 8.0 doesn't start a transfer
      early.

Change-Id: Id05b1a080911b71b94ef781c6e26d98165f02f67
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/78090
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
This commit is contained in:
Patrick Rudolph 2023-09-22 09:01:00 +02:00 committed by Felix Held
parent 44a48ce7a4
commit 155a21974a
1 changed files with 16 additions and 6 deletions
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22
src/southbridge/intel/common/spi.c
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@ -93,7 +93,7 @@ struct ich_spi_controller {
uint8_t *data;
unsigned int databytes;
uint8_t *status;
uint16_t *control;
uint8_t *control; /* Unaligned on ICH9 */
uint32_t *bbar;
uint32_t *fpr;
uint8_t fpr_max;
@ -300,7 +300,7 @@ void spi_init(void)
cntlr.data = (uint8_t *)ich7_spi->spid;
cntlr.databytes = sizeof(ich7_spi->spid);
cntlr.status = (uint8_t *)&ich7_spi->spis;
cntlr.control = &ich7_spi->spic;
cntlr.control = (uint8_t *)&ich7_spi->spic;
cntlr.bbar = &ich7_spi->bbar;
cntlr.preop = &ich7_spi->preop;
cntlr.fpr = &ich7_spi->pbr[0];
@ -317,7 +317,7 @@ void spi_init(void)
cntlr.data = (uint8_t *)ich9_spi->fdata;
cntlr.databytes = sizeof(ich9_spi->fdata);
cntlr.status = &ich9_spi->ssfs;
cntlr.control = (uint16_t *)ich9_spi->ssfc;
cntlr.control = ich9_spi->ssfc;
cntlr.bbar = &ich9_spi->bbar;
cntlr.preop = &ich9_spi->preop;
cntlr.fpr = &ich9_spi->pr[0];
@ -579,8 +579,13 @@ static int spi_ctrlr_xfer(const struct spi_slave *slave, const void *dout,
* bitesout size was 1, decremented to zero while executing
* spi_setup_opcode() above. Tell the chip to send the
* command.
*
* On ICH9 the control register is not natually aligned.
* Write the high byte first to prevent triggering a transfer
* when writing two bytes on the bus using outw instruction.
*/
writew_(control, cntlr.control);
writeb_(control >> 8, &cntlr.control[1]);
writeb_(control, &cntlr.control[0]);
/* wait for the result */
status = ich_status_poll(SPIS_CDS | SPIS_FCERR, 1);
@ -636,8 +641,13 @@ static int spi_ctrlr_xfer(const struct spi_slave *slave, const void *dout,
control |= SPIC_DS;
control |= (data_length - 1) << 8;
/* write it */
writew_(control, cntlr.control);
/*
* On ICH9 the control register is not natually aligned.
* Write the high byte first to prevent triggering a transfer
* when writing two bytes on the bus using outw instruction.
*/
writeb_(control >> 8, &cntlr.control[1]);
writeb_(control, &cntlr.control[0]);
/* Wait for Cycle Done Status or Flash Cycle Error. */
status = ich_status_poll(SPIS_CDS | SPIS_FCERR, 1);