From 155a21974ab720f8b9f1bc832d65b203f2f14ac7 Mon Sep 17 00:00:00 2001 From: Patrick Rudolph Date: Fri, 22 Sep 2023 09:01:00 +0200 Subject: sb/intel/common/spi: Fix I/O alignment MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 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 Reviewed-on: https://review.coreboot.org/c/coreboot/+/78090 Tested-by: build bot (Jenkins) Reviewed-by: Kyösti Mälkki --- src/southbridge/intel/common/spi.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-) (limited to 'src') diff --git a/src/southbridge/intel/common/spi.c b/src/southbridge/intel/common/spi.c index c984c6d435..93185d4884 100644 --- a/src/southbridge/intel/common/spi.c +++ b/src/southbridge/intel/common/spi.c @@ -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); -- cgit v1.2.3