linux-kernel - [PATCH] iommu: dart: Add suspend/resume support

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Message-Id: <20221205100907.10230-1-marcan@marcan.st>
Date:   Mon,  5 Dec 2022 19:09:07 +0900
From:   Hector Martin <marcan@...can.st>
To:     Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>
Cc:     Sven Peter <sven@...npeter.dev>,
        Alyssa Rosenzweig <alyssa@...enzweig.io>,
        asahi@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, Hector Martin <marcan@...can.st>
Subject: [PATCH] iommu: dart: Add suspend/resume support

We need to save/restore the TCR/TTBR registers, since they are lost
on power gate.

Signed-off-by: Hector Martin <marcan@...can.st>
---
 drivers/iommu/apple-dart.c | 50 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)

diff --git a/drivers/iommu/apple-dart.c b/drivers/iommu/apple-dart.c
index 4f4a323be0d0..ed524765ad87 100644
--- a/drivers/iommu/apple-dart.c
+++ b/drivers/iommu/apple-dart.c
@@ -121,6 +121,9 @@ struct apple_dart {
 
 	struct iommu_group *sid2group[DART_MAX_STREAMS];
 	struct iommu_device iommu;
+
+	u32 save_tcr[DART_MAX_STREAMS];
+	u32 save_ttbr[DART_MAX_STREAMS][DART_MAX_TTBR];
 };
 
 /*
@@ -932,6 +935,50 @@ static const struct apple_dart_hw apple_dart_hw_t6000 = {
 	.fmt = APPLE_DART2,
 };
 
+#ifdef CONFIG_PM_SLEEP
+static int apple_dart_suspend(struct device *dev)
+{
+	struct apple_dart *dart = dev_get_drvdata(dev);
+	unsigned int sid, idx;
+
+	for (sid = 0; sid < DART_MAX_STREAMS; sid++) {
+		dart->save_tcr[sid] = readl_relaxed(dart->regs + DART_TCR(sid));
+		for (idx = 0; idx < DART_MAX_TTBR; idx++)
+			dart->save_ttbr[sid][idx] =
+				readl_relaxed(dart->regs + DART_TTBR(sid, idx));
+	}
+
+	return 0;
+}
+
+static int apple_dart_resume(struct device *dev)
+{
+	struct apple_dart *dart = dev_get_drvdata(dev);
+	unsigned int sid, idx;
+	int ret;
+
+	ret = apple_dart_hw_reset(dart);
+	if (ret) {
+		dev_err(dev, "Failed to reset DART on resume\n");
+		return ret;
+	}
+
+	for (sid = 0; sid < DART_MAX_STREAMS; sid++) {
+		for (idx = 0; idx < DART_MAX_TTBR; idx++)
+			writel_relaxed(dart->save_ttbr[sid][idx],
+				       dart->regs + DART_TTBR(sid, idx));
+		writel_relaxed(dart->save_tcr[sid], dart->regs + DART_TCR(sid));
+	}
+
+	return 0;
+}
+
+static const struct dev_pm_ops apple_dart_pm_ops = {
+	.suspend	= apple_dart_suspend,
+	.resume		= apple_dart_resume,
+};
+#endif
+
 static const struct of_device_id apple_dart_of_match[] = {
 	{ .compatible = "apple,t8103-dart", .data = &apple_dart_hw_t8103 },
 	{ .compatible = "apple,t6000-dart", .data = &apple_dart_hw_t6000 },
@@ -944,6 +991,9 @@ static struct platform_driver apple_dart_driver = {
 		.name			= "apple-dart",
 		.of_match_table		= apple_dart_of_match,
 		.suppress_bind_attrs    = true,
+#ifdef CONFIG_PM_SLEEP
+		.pm			= &apple_dart_pm_ops,
+#endif
 	},
 	.probe	= apple_dart_probe,
 	.remove	= apple_dart_remove,
-- 
2.35.1