iommu/mediatek: Add a new tlb_lock for tlb_flush

The commit 4d689b61 ("iommu/io-pgtable-arm-v7s: Convert to IOMMU API
TLB sync") help move the tlb_sync of unmap from v7s into the iommu
framework. It helps add a new function "mtk_iommu_iotlb_sync", But it
lacked the lock, then it will cause the variable "tlb_flush_active"
may be changed unexpectedly, we could see this warning log randomly:

mtk-iommu 10205000.iommu: Partial TLB flush timed out, falling back to
full flush

The HW requires tlb_flush/tlb_sync in pairs strictly, this patch adds
a new tlb_lock for tlb operations to fix this issue.

Fixes: 4d689b61 ("iommu/io-pgtable-arm-v7s: Convert to IOMMU API TLB sync")
Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/mtk_iommu.c

@@ -219,22 +219,37 @@ static void mtk_iommu_tlb_sync(void *cookie)
 static void mtk_iommu_tlb_flush_walk(unsigned long iova, size_t size,
 				     size_t granule, void *cookie)
 {
+	struct mtk_iommu_data *data = cookie;
+	unsigned long flags;
+
+	spin_lock_irqsave(&data->tlb_lock, flags);
 	mtk_iommu_tlb_add_flush_nosync(iova, size, granule, false, cookie);
 	mtk_iommu_tlb_sync(cookie);
+	spin_unlock_irqrestore(&data->tlb_lock, flags);
 }
 
 static void mtk_iommu_tlb_flush_leaf(unsigned long iova, size_t size,
 				     size_t granule, void *cookie)
 {
+	struct mtk_iommu_data *data = cookie;
+	unsigned long flags;
+
+	spin_lock_irqsave(&data->tlb_lock, flags);
 	mtk_iommu_tlb_add_flush_nosync(iova, size, granule, true, cookie);
 	mtk_iommu_tlb_sync(cookie);
+	spin_unlock_irqrestore(&data->tlb_lock, flags);
 }
 
 static void mtk_iommu_tlb_flush_page_nosync(struct iommu_iotlb_gather *gather,
 					    unsigned long iova, size_t granule,
 					    void *cookie)
 {
+	struct mtk_iommu_data *data = cookie;
+	unsigned long flags;
+
+	spin_lock_irqsave(&data->tlb_lock, flags);
 	mtk_iommu_tlb_add_flush_nosync(iova, granule, granule, true, cookie);
+	spin_unlock_irqrestore(&data->tlb_lock, flags);
 }
 
 static const struct iommu_flush_ops mtk_iommu_flush_ops = {
@@ -453,7 +468,12 @@ static void mtk_iommu_flush_iotlb_all(struct iommu_domain *domain)
 static void mtk_iommu_iotlb_sync(struct iommu_domain *domain,
 				 struct iommu_iotlb_gather *gather)
 {
-	mtk_iommu_tlb_sync(mtk_iommu_get_m4u_data());
+	struct mtk_iommu_data *data = mtk_iommu_get_m4u_data();
+	unsigned long flags;
+
+	spin_lock_irqsave(&data->tlb_lock, flags);
+	mtk_iommu_tlb_sync(data);
+	spin_unlock_irqrestore(&data->tlb_lock, flags);
 }
 
 static phys_addr_t mtk_iommu_iova_to_phys(struct iommu_domain *domain,
@@ -733,6 +753,7 @@ static int mtk_iommu_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
+	spin_lock_init(&data->tlb_lock);
 	list_add_tail(&data->list, &m4ulist);
 
 	if (!iommu_present(&platform_bus_type))

drivers/iommu/mtk_iommu.h

@@ -58,6 +58,7 @@ struct mtk_iommu_data {
 	struct iommu_group		*m4u_group;
 	bool                            enable_4GB;
 	bool				tlb_flush_active;
+	spinlock_t			tlb_lock; /* lock for tlb range flush */
 
 	struct iommu_device		iommu;
 	const struct mtk_iommu_plat_data *plat_data;