Change in coreboot[master]: soc/amd/common/block/lpc/spi_dma: Add ability to verify SPI DMA hardware

[Raul Rangel (Code Review)]

Attention is currently required from: Jason Glenesk, Marshall Dawson, Felix Held.
Raul Rangel has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/56322 )

Change subject: soc/amd/common/block/lpc/spi_dma: Add ability to verify SPI DMA hardware
......................................................................

soc/amd/common/block/lpc/spi_dma: Add ability to verify SPI DMA hardware

The SPI DMA controller was not completely functional prior to RN/CZN.
This code can be used to sanity check the DMA hardware.

BUG=b:179699789
TEST=Boot guybrush with VERIFY=1 and make sure no DMA errors occur.

Signed-off-by: Raul E Rangel 
Change-Id: I2dd54cab86ad31b135a93d4667df346c60357337
---
M src/soc/amd/common/block/lpc/spi_dma.c
1 file changed, 24 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/22/56322/1

diff --git a/src/soc/amd/common/block/lpc/spi_dma.c b/src/soc/amd/common/block/lpc/spi_dma.c
index 00cd593..cd3958b 100644
--- a/src/soc/amd/common/block/lpc/spi_dma.c
+++ b/src/soc/amd/common/block/lpc/spi_dma.c
@@ -13,9 +13,16 @@
 #include <soc/pci_devs.h>
 #include <spi_flash.h>
 #include <string.h>
+#include <lib.h>
 #include <thread.h>
 #include <types.h>

+/*
+ * Set to 1 to verify the buffer contents after the DMA transaction.
+ * This is helpful in building confidence in the SPI DMA controller.
+ */
+#define VERIFY_BUFFER 0
+
 /* The ROM is memory mapped just below 4GiB. Form a pointer for the base. */
 #define rom_base ((void *)(uintptr_t)(0x100000000ULL - CONFIG_ROM_SIZE))

@@ -119,6 +126,9 @@
    ctrl |= LPC_ROM_DMA_CTRL_ERROR; /* Clear error */
    ctrl |= LPC_ROM_DMA_CTRL_START;

+	if (VERIFY_BUFFER)
+		memset(transaction->destination, 0xFC, transaction->transfer_size);
+
    pci_write_config32(SOC_LPC_DEV, LPC_ROM_DMA_EC_HOST_CONTROL, ctrl);
 }

@@ -135,6 +145,20 @@
    if (spi_dma_has_error())
    	return false;

+	if (VERIFY_BUFFER) {
+		uint8_t *mmap =
+			spi_dma_mmap(rd, transaction->source, transaction->transfer_size);
+		if (memcmp(mmap, transaction->destination, transaction->transfer_size)) {
+			printk(BIOS_ERR, "We had a DMA error!!!\n");
+			hexdump(mmap, transaction->transfer_size);
+			printk(BIOS_ERR, "---------------------\n");
+			hexdump(transaction->destination, transaction->transfer_size);
+			die("---------------------\n");
+		} else {
+			printk(BIOS_DEBUG, "Verification successful\n");
+		}
+	}
+
    transaction->destination += transaction->transfer_size;
    transaction->source += transaction->transfer_size;
    transaction->remaining -= transaction->transfer_size;