[PATCH 5.15.y 3/3] dmaengine: dw-edma: Add spinlock to protect DONE_INT_MASK and ABORT_INT_MASK

[Sasha Levin <sashal@kernel.org>]

From: Frank Li <Frank.Li@nxp.com>

[ Upstream commit 8ffba0171c6bbce5f093c6dba5a02c0805b31203 ]

The DONE_INT_MASK and ABORT_INT_MASK registers are shared by all DMA
channels, and modifying them requires a read-modify-write sequence.
Because this operation is not atomic, concurrent calls to
dw_edma_v0_core_start() can introduce race conditions if two channels
update these registers simultaneously.

Add a spinlock to serialize access to these registers and prevent race
conditions.

Fixes: 7e4b8a4fbe2c ("dmaengine: Add Synopsys eDMA IP version 0 support")
Cc: stable@vger.kernel.org
Signed-off-by: Frank Li <Frank.Li@nxp.com>
[den: update dw_edma.lock comment]
Link: https://lore.kernel.org/dmaengine/20260109-edma_ll-v2-1-5c0b27b2c664@nxp.com/
Signed-off-by: Koichiro Den <den@valinux.co.jp>
Link: https://patch.msgid.link/20260521142153.2957432-5-den@valinux.co.jp
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/dma/dw-edma/dw-edma-core.h    | 2 +-
 drivers/dma/dw-edma/dw-edma-v0-core.c | 6 ++++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/dw-edma/dw-edma-core.h b/drivers/dma/dw-edma/dw-edma-core.h
index 85df2d511907b1..3965153a774819 100644
--- a/drivers/dma/dw-edma/dw-edma-core.h
+++ b/drivers/dma/dw-edma/dw-edma-core.h
@@ -109,7 +109,7 @@ struct dw_edma {
 
 	struct dw_edma_chan		*chan;
 
-	raw_spinlock_t			lock;		/* Only for legacy */
+	raw_spinlock_t			lock;		/* Protect v0 shared registers */
 
 	struct dw_edma_chip             *chip;
 #ifdef CONFIG_DEBUG_FS
diff --git a/drivers/dma/dw-edma/dw-edma-v0-core.c b/drivers/dma/dw-edma/dw-edma-v0-core.c
index a45564dbcf6896..86967d390dfb46 100644
--- a/drivers/dma/dw-edma/dw-edma-v0-core.c
+++ b/drivers/dma/dw-edma/dw-edma-v0-core.c
@@ -358,6 +358,7 @@ void dw_edma_v0_core_start(struct dw_edma_chunk *chunk, bool first)
 {
 	struct dw_edma_chan *chan = chunk->chan;
 	struct dw_edma *dw = chan->dw;
+	unsigned long flags;
 	u32 tmp;
 
 	dw_edma_v0_core_write_chunk(chunk);
@@ -402,6 +403,8 @@ void dw_edma_v0_core_start(struct dw_edma_chunk *chunk, bool first)
 			}
 		}
 		/* Interrupt unmask - done, abort */
+		raw_spin_lock_irqsave(&dw->lock, flags);
+
 		tmp = GET_RW_32(dw, chan->dir, int_mask);
 		tmp &= ~FIELD_PREP(EDMA_V0_DONE_INT_MASK, BIT(chan->id));
 		tmp &= ~FIELD_PREP(EDMA_V0_ABORT_INT_MASK, BIT(chan->id));
@@ -410,6 +413,9 @@ void dw_edma_v0_core_start(struct dw_edma_chunk *chunk, bool first)
 		tmp = GET_RW_32(dw, chan->dir, linked_list_err_en);
 		tmp |= FIELD_PREP(EDMA_V0_LINKED_LIST_ERR_MASK, BIT(chan->id));
 		SET_RW_32(dw, chan->dir, linked_list_err_en, tmp);
+
+		raw_spin_unlock_irqrestore(&dw->lock, flags);
+
 		/* Channel control */
 		SET_CH_32(dw, chan->dir, chan->id, ch_control1,
 			  (DW_EDMA_V0_CCS | DW_EDMA_V0_LLE));
-- 
2.53.0