[PATCH 6.19 219/844] spi: spi-mem: Protect dirmap_create() with spi_mem_access_start/end

[Sasha Levin]

From: Chin-Ting Kuo <chin-ting_kuo@xxxxxxxxxxxxxx>

[ Upstream commit 53f826ff5e0e3ecb279862ca7cce1491b94bb017 ]

spi_mem_dirmap_create() may reconfigure controller-wide settings,
which can interfere with concurrent transfers to other devices
sharing the same SPI controller but using different chip selects.

Wrap the ->dirmap_create() callback with spi_mem_access_start() and
spi_mem_access_end() to serialize access and prevent cross-CS
interference during dirmap creation.

This patch has been verified on a setup where a SPI TPM is connected
to CS0 of a SPI controller, while a SPI NOR flash is connected to CS1
of the same controller. Without this patch, spi_mem_dirmap_create()
for the SPI NOR flash interferes with ongoing SPI TPM data transfers,
resulting in failure to create the TPM device. This was tested on an
ASPEED AST2700 EVB.

Signed-off-by: Chin-Ting Kuo <chin-ting_kuo@xxxxxxxxxxxxxx>
Reviewed-by: Paul Menzel <pmenzel@xxxxxxxxxxxxx>
Link: https://patch.msgid.link/20260120123005.1392071-2-chin-ting_kuo@xxxxxxxxxxxxxx
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/spi/spi-mem.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c
index 6c7921469b90b..965673bac98b9 100644
--- a/drivers/spi/spi-mem.c
+++ b/drivers/spi/spi-mem.c
@@ -719,9 +719,18 @@ spi_mem_dirmap_create(struct spi_mem *mem,
 
 	desc->mem = mem;
 	desc->info = *info;
-	if (ctlr->mem_ops && ctlr->mem_ops->dirmap_create)
+	if (ctlr->mem_ops && ctlr->mem_ops->dirmap_create) {
+		ret = spi_mem_access_start(mem);
+		if (ret) {
+			kfree(desc);
+			return ERR_PTR(ret);
+		}
+
 		ret = ctlr->mem_ops->dirmap_create(desc);
 
+		spi_mem_access_end(mem);
+	}
+
 	if (ret) {
 		desc->nodirmap = true;
 		if (!spi_mem_supports_op(desc->mem, &desc->info.op_tmpl))
-- 
2.51.0