iommu/mediatek: Fix two IOMMU share pagetable issue

Prepare for mt8188 to fix a two IOMMU HWs share pagetable issue.

We have two MM IOMMU HWs in mt8188, one is VPP-IOMMU, the other is
VDO-IOMMU. The 2 MM IOMMU HWs share pagetable don't work in this case:
 a) VPP-IOMMU probe firstly.
 b) VDO-IOMMU probe.
 c) The master for VDO-IOMMU probe (means frstdata is vpp-iommu).
 d) The master in another domain probe. No matter it is vdo or vpp.
Then it still create a new pagetable in step d). The problem is
"frstdata->bank[0]->m4u_dom" was not initialized. Then when d) enter, it
still create a new one.

In this patch, we create a new variable "share_dom" for this share
pgtable case, it should be helpful for readable. and put all the share
pgtable logic in the mtk_iommu_domain_finalise.

In mt8195, the master of VPP-IOMMU probes before than VDO-IOMMU
from its dtsi node sequence, we don't see this issue in it. Prepare for
mt8188.

Fixes: 645b87c190 ("iommu/mediatek: Fix 2 HW sharing pgtable issue")
Signed-off-by: Chengci.Xu <chengci.xu@mediatek.com>
Signed-off-by: Yong Wu <yong.wu@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Alexandre Mergnat <amergnat@baylibre.com>
Link: https://lore.kernel.org/r/20230602090227.7264-3-yong.wu@mediatek.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

drivers/iommu/mtk_iommu.c

@@ -258,6 +258,8 @@ struct mtk_iommu_data {
 	struct device			*smicomm_dev;
 
 	struct mtk_iommu_bank_data	*bank;
+	struct mtk_iommu_domain		*share_dom; /* For 2 HWs share pgtable */
+
 	struct regmap			*pericfg;
 	struct mutex			mutex; /* Protect m4u_group/m4u_dom above */
 
@@ -620,15 +622,14 @@ static int mtk_iommu_domain_finalise(struct mtk_iommu_domain *dom,
 				     struct mtk_iommu_data *data,
 				     unsigned int region_id)
 {
+	struct mtk_iommu_domain	*share_dom = data->share_dom;
 	const struct mtk_iommu_iova_region *region;
-	struct mtk_iommu_domain	*m4u_dom;
 
-	/* Always use bank0 in sharing pgtable case */
-	m4u_dom = data->bank[0].m4u_dom;
-	if (m4u_dom) {
-		dom->iop = m4u_dom->iop;
-		dom->cfg = m4u_dom->cfg;
-		dom->domain.pgsize_bitmap = m4u_dom->cfg.pgsize_bitmap;
+	/* Always use share domain in sharing pgtable case */
+	if (MTK_IOMMU_HAS_FLAG(data->plat_data, SHARE_PGTABLE) && share_dom) {
+		dom->iop = share_dom->iop;
+		dom->cfg = share_dom->cfg;
+		dom->domain.pgsize_bitmap = share_dom->cfg.pgsize_bitmap;
 		goto update_iova_region;
 	}
 
@@ -658,6 +659,9 @@ static int mtk_iommu_domain_finalise(struct mtk_iommu_domain *dom,
 	/* Update our support page sizes bitmap */
 	dom->domain.pgsize_bitmap = dom->cfg.pgsize_bitmap;
 
+	if (MTK_IOMMU_HAS_FLAG(data->plat_data, SHARE_PGTABLE))
+		data->share_dom = dom;
+
 update_iova_region:
 	/* Update the iova region for this domain */
 	region = data->plat_data->iova_region + region_id;
@@ -708,7 +712,9 @@ static int mtk_iommu_attach_device(struct iommu_domain *domain,
 		/* Data is in the frstdata in sharing pgtable case. */
 		frstdata = mtk_iommu_get_frst_data(hw_list);
 
+		mutex_lock(&frstdata->mutex);
 		ret = mtk_iommu_domain_finalise(dom, frstdata, region_id);
+		mutex_unlock(&frstdata->mutex);
 		if (ret) {
 			mutex_unlock(&dom->mutex);
 			return ret;