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From: Sumit Gupta <sumitg@nvidia.com>
To: <krzysztof.kozlowski@linaro.org>, <robh@kernel.org>,
	<conor+dt@kernel.org>, <maz@kernel.org>, <mark.rutland@arm.com>,
	<treding@nvidia.com>, <jonathanh@nvidia.com>
CC: <devicetree@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<linux-tegra@vger.kernel.org>, <amhetre@nvidia.com>, <bbasu@nvidia.com>,
	<sumitg@nvidia.com>
Subject: [Patch v2 2/2] memory: tegra: make sid and broadcast regions optional
Date: Tue, 2 Apr 2024 18:56:26 +0530
Message-ID: <20240402132626.24693-3-sumitg@nvidia.com>
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MC SID and Broadbast channel register access is restricted for Guest VM.
In Tegra MC driver, consider both the regions as optional and skip
access to restricted registers from Guest if a region is not present
in Guest DT.

Signed-off-by: Sumit Gupta <sumitg@nvidia.com>
---
 drivers/memory/tegra/mc.c       |  9 ++++++++-
 drivers/memory/tegra/mc.h       | 18 +++++++++---------
 drivers/memory/tegra/tegra186.c | 22 ++++++++++++----------
 3 files changed, 29 insertions(+), 20 deletions(-)

diff --git a/drivers/memory/tegra/mc.c b/drivers/memory/tegra/mc.c
index 224b488794e5..d819dab1b223 100644
--- a/drivers/memory/tegra/mc.c
+++ b/drivers/memory/tegra/mc.c
@@ -899,6 +899,7 @@ static void tegra_mc_num_channel_enabled(struct tegra_mc *mc)
 
 static int tegra_mc_probe(struct platform_device *pdev)
 {
+	struct resource *res;
 	struct tegra_mc *mc;
 	u64 mask;
 	int err;
@@ -923,7 +924,13 @@ static int tegra_mc_probe(struct platform_device *pdev)
 	/* length of MC tick in nanoseconds */
 	mc->tick = 30;
 
-	mc->regs = devm_platform_ioremap_resource(pdev, 0);
+	if (mc->soc->num_channels) {
+		res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "sid");
+		if (res)
+			mc->regs = devm_ioremap_resource(&pdev->dev, res);
+	} else {
+		mc->regs = devm_platform_ioremap_resource(pdev, 0);
+	}
 	if (IS_ERR(mc->regs))
 		return PTR_ERR(mc->regs);
 
diff --git a/drivers/memory/tegra/mc.h b/drivers/memory/tegra/mc.h
index c3f6655bec60..5cdb9451f364 100644
--- a/drivers/memory/tegra/mc.h
+++ b/drivers/memory/tegra/mc.h
@@ -112,11 +112,11 @@ icc_provider_to_tegra_mc(struct icc_provider *provider)
 static inline u32 mc_ch_readl(const struct tegra_mc *mc, int ch,
 			      unsigned long offset)
 {
-	if (!mc->bcast_ch_regs)
-		return 0;
-
-	if (ch == MC_BROADCAST_CHANNEL)
+	if (ch == MC_BROADCAST_CHANNEL) {
+		if (!mc->bcast_ch_regs)
+			return 0;
 		return readl_relaxed(mc->bcast_ch_regs + offset);
+	}
 
 	return readl_relaxed(mc->ch_regs[ch] + offset);
 }
@@ -124,13 +124,13 @@ static inline u32 mc_ch_readl(const struct tegra_mc *mc, int ch,
 static inline void mc_ch_writel(const struct tegra_mc *mc, int ch,
 				u32 value, unsigned long offset)
 {
-	if (!mc->bcast_ch_regs)
-		return;
-
-	if (ch == MC_BROADCAST_CHANNEL)
+	if (ch == MC_BROADCAST_CHANNEL) {
+		if (!mc->bcast_ch_regs)
+			return;
 		writel_relaxed(value, mc->bcast_ch_regs + offset);
-	else
+	} else {
 		writel_relaxed(value, mc->ch_regs[ch] + offset);
+	}
 }
 
 static inline u32 mc_readl(const struct tegra_mc *mc, unsigned long offset)
diff --git a/drivers/memory/tegra/tegra186.c b/drivers/memory/tegra/tegra186.c
index 1b3183951bfe..7b5e9bd13ffd 100644
--- a/drivers/memory/tegra/tegra186.c
+++ b/drivers/memory/tegra/tegra186.c
@@ -26,20 +26,16 @@
 static int tegra186_mc_probe(struct tegra_mc *mc)
 {
 	struct platform_device *pdev = to_platform_device(mc->dev);
+	struct resource *res;
 	unsigned int i;
 	char name[8];
 	int err;
 
-	mc->bcast_ch_regs = devm_platform_ioremap_resource_byname(pdev, "broadcast");
-	if (IS_ERR(mc->bcast_ch_regs)) {
-		if (PTR_ERR(mc->bcast_ch_regs) == -EINVAL) {
-			dev_warn(&pdev->dev,
-				 "Broadcast channel is missing, please update your device-tree\n");
-			mc->bcast_ch_regs = NULL;
-			goto populate;
-		}
-
-		return PTR_ERR(mc->bcast_ch_regs);
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "broadcast");
+	if (res) {
+		mc->bcast_ch_regs = devm_ioremap_resource(&pdev->dev, res);
+		if (IS_ERR(mc->bcast_ch_regs))
+			return PTR_ERR(mc->bcast_ch_regs);
 	}
 
 	mc->ch_regs = devm_kcalloc(mc->dev, mc->soc->num_channels, sizeof(*mc->ch_regs),
@@ -121,6 +117,9 @@ static int tegra186_mc_probe_device(struct tegra_mc *mc, struct device *dev)
 	if (!tegra_dev_iommu_get_stream_id(dev, &sid))
 		return 0;
 
+	if (!mc->regs)
+		return 0;
+
 	while (!of_parse_phandle_with_args(dev->of_node, "interconnects", "#interconnect-cells",
 					   index, &args)) {
 		if (args.np == mc->dev->of_node && args.args_count != 0) {
@@ -146,6 +145,9 @@ static int tegra186_mc_resume(struct tegra_mc *mc)
 #if IS_ENABLED(CONFIG_IOMMU_API)
 	unsigned int i;
 
+	if (!mc->regs)
+		return 0;
+
 	for (i = 0; i < mc->soc->num_clients; i++) {
 		const struct tegra_mc_client *client = &mc->soc->clients[i];
 
-- 
2.17.1