soc/amd/common/block/lpc/spi_dma: Use mutex to protect DMA registers
Once we enable COOP_MULTITASKING, we need to guarantee that we don't
have multiple threads trying to access the DMA hardware.
BUG=b:179699789
TEST=Boot guybrush with APOB patches.
Signed-off-by: Raul E Rangel <rrangel@chromium.org>
Change-Id: Ibb8e31c95d6722521425772f4210af45626c8e09
Reviewed-on: https://review.coreboot.org/c/coreboot/+/56231
Reviewed-by: Karthik Ramasubramanian <kramasub@google.com>
Reviewed-by: Furquan Shaikh <furquan@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/soc/amd/common/block/lpc/spi_dma.c b/src/soc/amd/common/block/lpc/spi_dma.c
index b00b8ac..fdc4f32 100644
--- a/src/soc/amd/common/block/lpc/spi_dma.c
+++ b/src/soc/amd/common/block/lpc/spi_dma.c
@@ -13,6 +13,7 @@
#include <soc/pci_devs.h>
#include <spi_flash.h>
#include <string.h>
+#include <thread.h>
#include <types.h>
/* The ROM is memory mapped just below 4GiB. Form a pointer for the base. */
@@ -164,6 +165,8 @@
return false;
}
+static struct thread_mutex spi_dma_hw_mutex;
+
static ssize_t spi_dma_readat_dma(const struct region_device *rd, void *destination,
size_t source, size_t size)
{
@@ -177,12 +180,16 @@
printk(BIOS_SPEW, "%s: start: dest: %p, source: %#zx, size: %zu\n", __func__,
destination, source, size);
+ thread_mutex_lock(&spi_dma_hw_mutex);
+
start_spi_dma_transaction(&transaction);
do {
udelay(2);
} while (continue_spi_dma_transaction(rd, &transaction));
+ thread_mutex_unlock(&spi_dma_hw_mutex);
+
printk(BIOS_SPEW, "%s: end: dest: %p, source: %#zx, remaining: %zu\n",
__func__, destination, source, transaction.remaining);