[PATCH linux dev-5.10 2/2] soc: aspeed: Re-enable XDMA on AST2600

[Joel Stanley]

Recent builds of the vendor u-boot tree disable features of the
BMC that may allow unwanted access if not correctly configured. This
includes the PCIe DMA (XDMA) functionality.

The bit to "un-disable" it is in the SCU. It does not appear to matter
when it is cleared, as long as it is cleared before attempting a
transfer.

Signed-off-by: Joel Stanley <joel at jms.id.au>
---
 drivers/soc/aspeed/aspeed-xdma.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/soc/aspeed/aspeed-xdma.c b/drivers/soc/aspeed/aspeed-xdma.c
index e6b4744bda64..48cfe30c90ad 100644
--- a/drivers/soc/aspeed/aspeed-xdma.c
+++ b/drivers/soc/aspeed/aspeed-xdma.c
@@ -34,6 +34,9 @@
 #define SCU_AST2600_MISC_CTRL			0x0c0
 #define  SCU_AST2600_MISC_CTRL_XDMA_BMC		 BIT(8)
 
+#define SCU_AST2600_DEBUG_CTRL			0x0c8
+#define  DEBUG_CTRL_XDMA_DISABLE	 	 BIT(2)
+
 #define SCU_AST2500_PCIE_CONF			0x180
 #define SCU_AST2600_PCIE_CONF			0xc20
 #define  SCU_PCIE_CONF_VGA_EN			 BIT(0)
@@ -831,10 +834,15 @@ static int aspeed_xdma_init_scu(struct aspeed_xdma *ctx, struct device *dev)
 		regmap_update_bits(scu, ctx->chip->scu_pcie_conf, bmc | vga,
 				   selection);
 
-		if (ctx->chip->scu_misc_ctrl)
+		if (ctx->chip->scu_misc_ctrl) {
 			regmap_update_bits(scu, ctx->chip->scu_misc_ctrl,
 					   SCU_AST2600_MISC_CTRL_XDMA_BMC,
 					   SCU_AST2600_MISC_CTRL_XDMA_BMC);
+
+			/* Allow XDMA to be used on AST2600 */
+			regmap_update_bits(scu, SCU_AST2600_DEBUG_CTRL,
+					   DEBUG_CTRL_XDMA_DISABLE, 0);
+		}
 	} else {
 		dev_warn(dev, "Unable to configure PCIe: %ld; continuing.\n",
 			 PTR_ERR(scu));
-- 
2.32.0