[PATCH 10/12] wifi: mt76: mt7996: add locking for accessing mapped registers

[Shayne Chen]

A race condition was observed when accessing mapped registers, so add
locking to protect against concurrent access.

Signed-off-by: Shayne Chen <shayne.chen at mediatek.com>
---
 .../net/wireless/mediatek/mt76/mt7996/mmio.c  | 64 ++++++++++++-------
 .../wireless/mediatek/mt76/mt7996/mt7996.h    |  3 +-
 2 files changed, 43 insertions(+), 24 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/mt7996/mmio.c b/drivers/net/wireless/mediatek/mt76/mt7996/mmio.c
index c50d89a445e9..ff6a335e1fa7 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7996/mmio.c
+++ b/drivers/net/wireless/mediatek/mt76/mt7996/mmio.c
@@ -140,7 +140,6 @@ static u32 mt7996_reg_map_l1(struct mt7996_dev *dev, u32 addr)
 	u32 offset = FIELD_GET(MT_HIF_REMAP_L1_OFFSET, addr);
 	u32 base = FIELD_GET(MT_HIF_REMAP_L1_BASE, addr);
 
-	dev->reg_l1_backup = dev->bus_ops->rr(&dev->mt76, MT_HIF_REMAP_L1);
 	dev->bus_ops->rmw(&dev->mt76, MT_HIF_REMAP_L1,
 			  MT_HIF_REMAP_L1_MASK,
 			  FIELD_PREP(MT_HIF_REMAP_L1_MASK, base));
@@ -155,7 +154,6 @@ static u32 mt7996_reg_map_l2(struct mt7996_dev *dev, u32 addr)
 	u32 offset = FIELD_GET(MT_HIF_REMAP_L2_OFFSET, addr);
 	u32 base = FIELD_GET(MT_HIF_REMAP_L2_BASE, addr);
 
-	dev->reg_l2_backup = dev->bus_ops->rr(&dev->mt76, MT_HIF_REMAP_L2);
 	dev->bus_ops->rmw(&dev->mt76, MT_HIF_REMAP_L2,
 			  MT_HIF_REMAP_L2_MASK,
 			  FIELD_PREP(MT_HIF_REMAP_L2_MASK, base));
@@ -165,26 +163,10 @@ static u32 mt7996_reg_map_l2(struct mt7996_dev *dev, u32 addr)
 	return MT_HIF_REMAP_BASE_L2 + offset;
 }
 
-static void mt7996_reg_remap_restore(struct mt7996_dev *dev)
-{
-	/* remap to ori status */
-	if (unlikely(dev->reg_l1_backup)) {
-		dev->bus_ops->wr(&dev->mt76, MT_HIF_REMAP_L1, dev->reg_l1_backup);
-		dev->reg_l1_backup = 0;
-	}
-
-	if (dev->reg_l2_backup) {
-		dev->bus_ops->wr(&dev->mt76, MT_HIF_REMAP_L2, dev->reg_l2_backup);
-		dev->reg_l2_backup = 0;
-	}
-}
-
 static u32 __mt7996_reg_addr(struct mt7996_dev *dev, u32 addr)
 {
 	int i;
 
-	mt7996_reg_remap_restore(dev);
-
 	if (addr < 0x100000)
 		return addr;
 
@@ -201,6 +183,11 @@ static u32 __mt7996_reg_addr(struct mt7996_dev *dev, u32 addr)
 		return dev->reg.map[i].mapped + ofs;
 	}
 
+	return 0;
+}
+
+static u32 __mt7996_reg_remap_addr(struct mt7996_dev *dev, u32 addr)
+{
 	if ((addr >= MT_INFRA_BASE && addr < MT_WFSYS0_PHY_START) ||
 	    (addr >= MT_WFSYS0_PHY_START && addr < MT_WFSYS1_PHY_START) ||
 	    (addr >= MT_WFSYS1_PHY_START && addr <= MT_WFSYS1_PHY_END))
@@ -225,28 +212,60 @@ void mt7996_memcpy_fromio(struct mt7996_dev *dev, void *buf, u32 offset,
 {
 	u32 addr = __mt7996_reg_addr(dev, offset);
 
-	memcpy_fromio(buf, dev->mt76.mmio.regs + addr, len);
+	if (addr) {
+		memcpy_fromio(buf, dev->mt76.mmio.regs + addr, len);
+		return;
+	}
+
+	spin_lock_bh(&dev->reg_lock);
+	memcpy_fromio(buf, dev->mt76.mmio.regs +
+			   __mt7996_reg_remap_addr(dev, offset), len);
+	spin_unlock_bh(&dev->reg_lock);
 }
 
 static u32 mt7996_rr(struct mt76_dev *mdev, u32 offset)
 {
 	struct mt7996_dev *dev = container_of(mdev, struct mt7996_dev, mt76);
+	u32 addr = __mt7996_reg_addr(dev, offset), val;
+
+	if (addr)
+		return dev->bus_ops->rr(mdev, addr);
 
-	return dev->bus_ops->rr(mdev, __mt7996_reg_addr(dev, offset));
+	spin_lock_bh(&dev->reg_lock);
+	val = dev->bus_ops->rr(mdev, __mt7996_reg_remap_addr(dev, offset));
+	spin_unlock_bh(&dev->reg_lock);
+
+	return val;
 }
 
 static void mt7996_wr(struct mt76_dev *mdev, u32 offset, u32 val)
 {
 	struct mt7996_dev *dev = container_of(mdev, struct mt7996_dev, mt76);
+	u32 addr = __mt7996_reg_addr(dev, offset);
 
-	dev->bus_ops->wr(mdev, __mt7996_reg_addr(dev, offset), val);
+	if (addr) {
+		dev->bus_ops->wr(mdev, addr, val);
+		return;
+	}
+
+	spin_lock_bh(&dev->reg_lock);
+	dev->bus_ops->wr(mdev, __mt7996_reg_remap_addr(dev, offset), val);
+	spin_unlock_bh(&dev->reg_lock);
 }
 
 static u32 mt7996_rmw(struct mt76_dev *mdev, u32 offset, u32 mask, u32 val)
 {
 	struct mt7996_dev *dev = container_of(mdev, struct mt7996_dev, mt76);
+	u32 addr = __mt7996_reg_addr(dev, offset);
+
+	if (addr)
+		return dev->bus_ops->rmw(mdev, addr, mask, val);
+
+	spin_lock_bh(&dev->reg_lock);
+	val = dev->bus_ops->rmw(mdev, __mt7996_reg_remap_addr(dev, offset), mask, val);
+	spin_unlock_bh(&dev->reg_lock);
 
-	return dev->bus_ops->rmw(mdev, __mt7996_reg_addr(dev, offset), mask, val);
+	return val;
 }
 
 #ifdef CONFIG_NET_MEDIATEK_SOC_WED
@@ -421,6 +440,7 @@ static int mt7996_mmio_init(struct mt76_dev *mdev,
 
 	dev = container_of(mdev, struct mt7996_dev, mt76);
 	mt76_mmio_init(&dev->mt76, mem_base);
+	spin_lock_init(&dev->reg_lock);
 
 	switch (device_id) {
 	case 0x7990:
diff --git a/drivers/net/wireless/mediatek/mt76/mt7996/mt7996.h b/drivers/net/wireless/mediatek/mt76/mt7996/mt7996.h
index 8154ad37827f..36d1f247d55a 100644
--- a/drivers/net/wireless/mediatek/mt76/mt7996/mt7996.h
+++ b/drivers/net/wireless/mediatek/mt76/mt7996/mt7996.h
@@ -325,8 +325,7 @@ struct mt7996_dev {
 		u8 n_agrt;
 	} twt;
 
-	u32 reg_l1_backup;
-	u32 reg_l2_backup;
+	spinlock_t reg_lock;
 
 	u8 wtbl_size_group;
 };
-- 
2.39.2