[PATCH 10/21] iommu/mediatek: Add device link for smi-common and m4u

[Yong Wu]

In the lastest SoC, M4U has its special power domain. thus, If the engine
begin to work, it should help enable the power for M4U firstly.
Currently if the engine work, it always enable the power/clocks for
smi-larbs/smi-common. This patch adds device_link for smi-common and M4U.
then, if smi-common power is enabled, the M4U power also is powered on
automatically.

In this patch, a M4U connects with several smi-larbs and their smi-common
always are the same, thus it adds the device-link once is enough.
And the devicelink only is needed while m4u has power-domain.

Signed-off-by: Yong Wu <yong.wu at mediatek.com>
---
 drivers/iommu/mtk_iommu.c | 26 +++++++++++++++++++++++++-
 drivers/iommu/mtk_iommu.h |  1 +
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
index a6412d454e0b..931fdd19c8f3 100644
--- a/drivers/iommu/mtk_iommu.c
+++ b/drivers/iommu/mtk_iommu.c
@@ -675,8 +675,9 @@ static int mtk_iommu_probe(struct platform_device *pdev)
 		return larb_nr;
 
 	for (i = 0; i < larb_nr; i++) {
-		struct device_node *larbnode;
+		struct device_node *larbnode, *smicomm_node;
 		struct platform_device *plarbdev;
+		struct device_link *link;
 		u32 id;
 
 		larbnode = of_parse_phandle(dev->of_node, "mediatek,larbs", i);
@@ -701,6 +702,28 @@ static int mtk_iommu_probe(struct platform_device *pdev)
 
 		component_match_add_release(dev, &match, release_of,
 					    compare_of, larbnode);
+
+		/*
+		 * Add link for smi-common and m4u once is ok. and the link is
+		 * only needed while m4u has power-domain.
+		 */
+		if (i || !pm_runtime_enabled(dev))
+			continue;
+
+		smicomm_node = of_parse_phandle(larbnode, "mediatek,smi", 0);
+		if (!smicomm_node) {
+			of_node_put(larbnode);
+			return -EINVAL;
+		}
+
+		plarbdev = of_find_device_by_node(smicomm_node);
+		of_node_put(smicomm_node);
+		data->smicomm_dev = &plarbdev->dev;
+
+		link = device_link_add(&plarbdev->dev, dev,
+				       DL_FLAG_STATELESS | DL_FLAG_PM_RUNTIME);
+		if (!link)
+			dev_err(dev, "Unable link %s.\n", plarbdev->name);
 	}
 
 	platform_set_drvdata(pdev, data);
@@ -740,6 +763,7 @@ static int mtk_iommu_remove(struct platform_device *pdev)
 	if (iommu_present(&platform_bus_type))
 		bus_set_iommu(&platform_bus_type, NULL);
 
+	device_link_remove(data->smicomm_dev, &pdev->dev);
 	clk_disable_unprepare(data->bclk);
 	devm_free_irq(&pdev->dev, data->irq, data);
 	component_master_del(&pdev->dev, &mtk_iommu_com_ops);
diff --git a/drivers/iommu/mtk_iommu.h b/drivers/iommu/mtk_iommu.h
index 1a087af50a4e..e965bcb169c0 100644
--- a/drivers/iommu/mtk_iommu.h
+++ b/drivers/iommu/mtk_iommu.h
@@ -66,6 +66,7 @@ struct mtk_iommu_data {
 
 	struct iommu_device		iommu;
 	const struct mtk_iommu_plat_data *plat_data;
+	struct device			*smicomm_dev;
 
 	struct list_head		list;
 	struct mtk_smi_larb_iommu	larb_imu[MTK_LARB_NR_MAX];
-- 
2.18.0