memory: tegra: Implement SID override programming

Instead of programming all SID overrides during early boot, perform the
operation on-demand after the SMMU translations have been set up for a
device. This reuses data from device tree to match memory clients for a
device and programs the SID specified in device tree, which corresponds
to the SID used for the SMMU context banks for the device.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: https://lore.kernel.org/r/20210603164632.1000458-2-thierry.reding@gmail.com
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>

drivers/memory/tegra/mc.c

@@ -97,6 +97,15 @@ struct tegra_mc *devm_tegra_memory_controller_get(struct device *dev)
 }
 EXPORT_SYMBOL_GPL(devm_tegra_memory_controller_get);
 
+int tegra_mc_probe_device(struct tegra_mc *mc, struct device *dev)
+{
+	if (mc->soc->ops && mc->soc->ops->probe_device)
+		return mc->soc->ops->probe_device(mc, dev);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(tegra_mc_probe_device);
+
 static int tegra_mc_block_dma_common(struct tegra_mc *mc,
 				     const struct tegra_mc_reset *rst)
 {

drivers/memory/tegra/tegra186.c

@@ -4,6 +4,7 @@
  */
 
 #include <linux/io.h>
+#include <linux/iommu.h>
 #include <linux/module.h>
 #include <linux/mod_devicetable.h>
 #include <linux/of_device.h>
@@ -15,6 +16,10 @@
 #include <dt-bindings/memory/tegra186-mc.h>
 #endif
 
+#define MC_SID_STREAMID_OVERRIDE_MASK GENMASK(7, 0)
+#define MC_SID_STREAMID_SECURITY_WRITE_ACCESS_DISABLED BIT(16)
+#define MC_SID_STREAMID_SECURITY_OVERRIDE BIT(8)
+
 static void tegra186_mc_program_sid(struct tegra_mc *mc)
 {
 	unsigned int i;
@@ -66,10 +71,77 @@ static int tegra186_mc_resume(struct tegra_mc *mc)
 	return 0;
 }
 
+static void tegra186_mc_client_sid_override(struct tegra_mc *mc,
+					    const struct tegra_mc_client *client,
+					    unsigned int sid)
+{
+	u32 value, old;
+
+	value = readl(mc->regs + client->regs.sid.security);
+	if ((value & MC_SID_STREAMID_SECURITY_OVERRIDE) == 0) {
+		/*
+		 * If the secure firmware has locked this down the override
+		 * for this memory client, there's nothing we can do here.
+		 */
+		if (value & MC_SID_STREAMID_SECURITY_WRITE_ACCESS_DISABLED)
+			return;
+
+		/*
+		 * Otherwise, try to set the override itself. Typically the
+		 * secure firmware will never have set this configuration.
+		 * Instead, it will either have disabled write access to
+		 * this field, or it will already have set an explicit
+		 * override itself.
+		 */
+		WARN_ON((value & MC_SID_STREAMID_SECURITY_OVERRIDE) == 0);
+
+		value |= MC_SID_STREAMID_SECURITY_OVERRIDE;
+		writel(value, mc->regs + client->regs.sid.security);
+	}
+
+	value = readl(mc->regs + client->regs.sid.override);
+	old = value & MC_SID_STREAMID_OVERRIDE_MASK;
+
+	if (old != sid) {
+		dev_dbg(mc->dev, "overriding SID %x for %s with %x\n", old,
+			client->name, sid);
+		writel(sid, mc->regs + client->regs.sid.override);
+	}
+}
+
+static int tegra186_mc_probe_device(struct tegra_mc *mc, struct device *dev)
+{
+#if IS_ENABLED(CONFIG_IOMMU_API)
+	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
+	struct of_phandle_args args;
+	unsigned int i, index = 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) {
+			for (i = 0; i < mc->soc->num_clients; i++) {
+				const struct tegra_mc_client *client = &mc->soc->clients[i];
+
+				if (client->id == args.args[0]) {
+					u32 sid = fwspec->ids[0] & MC_SID_STREAMID_OVERRIDE_MASK;
+
+					tegra186_mc_client_sid_override(mc, client, sid);
+				}
+			}
+		}
+
+		index++;
+	}
+#endif
+
+	return 0;
+}
+
 const struct tegra_mc_ops tegra186_mc_ops = {
 	.probe = tegra186_mc_probe,
 	.remove = tegra186_mc_remove,
 	.resume = tegra186_mc_resume,
+	.probe_device = tegra186_mc_probe_device,
 };
 
 #if defined(CONFIG_ARCH_TEGRA_186_SOC)

include/soc/tegra/mc.h

@@ -180,6 +180,7 @@ struct tegra_mc_ops {
 	int (*suspend)(struct tegra_mc *mc);
 	int (*resume)(struct tegra_mc *mc);
 	irqreturn_t (*handle_irq)(int irq, void *data);
+	int (*probe_device)(struct tegra_mc *mc, struct device *dev);
 };
 
 struct tegra_mc_soc {
@@ -244,4 +245,6 @@ devm_tegra_memory_controller_get(struct device *dev)
 }
 #endif
 
+int tegra_mc_probe_device(struct tegra_mc *mc, struct device *dev);
+
 #endif /* __SOC_TEGRA_MC_H__ */