[PATCH v3 15/24] iommu/mediatek: Add power-domain operation

[Yong Wu <yong.wu@mediatek.com>]

In the previous SoC, the M4U HW is in the EMI power domain which is
always on. the latest M4U is in the display power domain which may be
turned on/off, thus we have to add pm_runtime interface for it.

When the engine work, the engine always enable the power and clocks for
smi-larb/smi-common, then the M4U's power will always be powered on
automatically via the device link with smi-common.

Note: we don't enable the M4U power in iommu_map/unmap for tlb flush.
If its power already is on, of course it is ok. if the power is off,
the main tlb will be reset while M4U power on, thus the tlb flush while
m4u power off is unnecessary, just skip it.

Signed-off-by: Yong Wu <yong.wu@mediatek.com>
---
 drivers/iommu/mtk_iommu.c | 27 ++++++++++++++++++++++-----
 1 file changed, 22 insertions(+), 5 deletions(-)

diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
index 052eb72acf69..1e6e6d3fa7f1 100644
--- a/drivers/iommu/mtk_iommu.c
+++ b/drivers/iommu/mtk_iommu.c
@@ -196,6 +196,10 @@ static void mtk_iommu_tlb_flush_range_sync(unsigned long iova, size_t size,
 	u32 tmp;
 
 	for_each_m4u(data) {
+		/* skip tlb flush when pm is not active. */
+		if (!pm_runtime_active(data->dev))
+			continue;
+
 		spin_lock_irqsave(&data->tlb_lock, flags);
 		writel_relaxed(F_INVLD_EN1 | F_INVLD_EN0,
 			       data->base + data->plat_data->inv_sel_reg);
@@ -380,6 +384,7 @@ static int mtk_iommu_attach_device(struct iommu_domain *domain,
 {
 	struct mtk_iommu_data *data = dev_iommu_priv_get(dev);
 	struct mtk_iommu_domain *dom = to_mtk_domain(domain);
+	struct device *m4udev = data->dev;
 	int ret;
 
 	if (!data)
@@ -387,12 +392,18 @@ static int mtk_iommu_attach_device(struct iommu_domain *domain,
 
 	/* Update the pgtable base address register of the M4U HW */
 	if (!data->m4u_dom) {
+		ret = pm_runtime_get_sync(m4udev);
+		if (ret < 0)
+			return ret;
 		ret = mtk_iommu_hw_init(data);
-		if (ret)
+		if (ret) {
+			pm_runtime_put(m4udev);
 			return ret;
+		}
 		data->m4u_dom = dom;
 		writel(dom->cfg.arm_v7s_cfg.ttbr & MMU_PT_ADDR_MASK,
 		       data->base + REG_MMU_PT_BASE_ADDR);
+		pm_runtime_put(m4udev);
 	}
 
 	mtk_iommu_config(data, dev, true);
@@ -742,10 +753,13 @@ static int mtk_iommu_probe(struct platform_device *pdev)
 	if (dev->pm_domain) {
 		struct device_link *link;
 
+		pm_runtime_enable(dev);
+
 		link = device_link_add(data->smicomm_dev, dev,
 				       DL_FLAG_STATELESS | DL_FLAG_PM_RUNTIME);
 		if (!link) {
 			dev_err(dev, "Unable link %s.\n", dev_name(data->smicomm_dev));
+			pm_runtime_disable(dev);
 			return -EINVAL;
 		}
 	}
@@ -763,8 +777,10 @@ static int mtk_iommu_remove(struct platform_device *pdev)
 		bus_set_iommu(&platform_bus_type, NULL);
 
 	clk_disable_unprepare(data->bclk);
-	if (pdev->dev.pm_domain)
+	if (pdev->dev.pm_domain) {
 		device_link_remove(data->smicomm_dev, &pdev->dev);
+		pm_runtime_disable(&pdev->dev);
+	}
 	devm_free_irq(&pdev->dev, data->irq, data);
 	component_master_del(&pdev->dev, &mtk_iommu_com_ops);
 	return 0;
@@ -796,6 +812,9 @@ static int __maybe_unused mtk_iommu_runtime_resume(struct device *dev)
 	void __iomem *base = data->base;
 	int ret;
 
+	/* Avoid first resume to affect the default value of registers below. */
+	if (!m4u_dom)
+		return 0;
 	ret = clk_prepare_enable(data->bclk);
 	if (ret) {
 		dev_err(data->dev, "Failed to enable clk(%d) in resume\n", ret);
@@ -809,9 +828,7 @@ static int __maybe_unused mtk_iommu_runtime_resume(struct device *dev)
 	writel_relaxed(reg->int_main_control, base + REG_MMU_INT_MAIN_CONTROL);
 	writel_relaxed(reg->ivrp_paddr, base + REG_MMU_IVRP_PADDR);
 	writel_relaxed(reg->vld_pa_rng, base + REG_MMU_VLD_PA_RNG);
-	if (m4u_dom)
-		writel(m4u_dom->cfg.arm_v7s_cfg.ttbr & MMU_PT_ADDR_MASK,
-		       base + REG_MMU_PT_BASE_ADDR);
+	writel(m4u_dom->cfg.arm_v7s_cfg.ttbr & MMU_PT_ADDR_MASK, base + REG_MMU_PT_BASE_ADDR);
 	return 0;
 }
 
-- 
2.18.0