memory: tegra-mc: Add interconnect framework

Add common SoC-agnostic ICC framework which turns Tegra Memory Controller
into a memory interconnection provider. This allows us to use interconnect
API for tuning of memory configurations.

Signed-off-by: Dmitry Osipenko <[e-mail]>
Tested-by: Peter Geis <[e-mail]>
Tested-by: Nicolas Chauvet <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Krzysztof Kozlowski <[e-mail]>

drivers/memory/tegra/Kconfig

···
 	bool "NVIDIA Tegra Memory Controller support"
 	default y
 	depends on ARCH_TEGRA
+	select INTERCONNECT
 	help
 	  This driver supports the Memory Controller (MC) hardware found on
 	  NVIDIA Tegra SoCs.

drivers/memory/tegra/mc.c

···
 	return IRQ_HANDLED;
 }
 
+/*
+ * Memory Controller (MC) has few Memory Clients that are issuing memory
+ * bandwidth allocation requests to the MC interconnect provider. The MC
+ * provider aggregates the requests and then sends the aggregated request
+ * up to the External Memory Controller (EMC) interconnect provider which
+ * re-configures hardware interface to External Memory (EMEM) in accordance
+ * to the required bandwidth. Each MC interconnect node represents an
+ * individual Memory Client.
+ *
+ * Memory interconnect topology:
+ *
+ *               +----+
+ * +--------+    |    |
+ * | TEXSRD +--->+    |
+ * +--------+    |    |
+ *               |    |    +-----+    +------+
+ *    ...        | MC +--->+ EMC +--->+ EMEM |
+ *               |    |    +-----+    +------+
+ * +--------+    |    |
+ * | DISP.. +--->+    |
+ * +--------+    |    |
+ *               +----+
+ */
+static int tegra_mc_interconnect_setup(struct tegra_mc *mc)
+{
+	struct icc_node *node;
+	unsigned int i;
+	int err;
+
+	/* older device-trees don't have interconnect properties */
+	if (!device_property_present(mc->dev, "#interconnect-cells") ||
+	    !mc->soc->icc_ops)
+		return 0;
+
+	mc->provider.dev = mc->dev;
+	mc->provider.data = &mc->provider;
+	mc->provider.set = mc->soc->icc_ops->set;
+	mc->provider.aggregate = mc->soc->icc_ops->aggregate;
+	mc->provider.xlate_extended = mc->soc->icc_ops->xlate_extended;
+
+	err = icc_provider_add(&mc->provider);
+	if (err)
+		return err;
+
+	/* create Memory Controller node */
+	node = icc_node_create(TEGRA_ICC_MC);
+	if (IS_ERR(node)) {
+		err = PTR_ERR(node);
+		goto del_provider;
+	}
+
+	node->name = "Memory Controller";
+	icc_node_add(node, &mc->provider);
+
+	/* link Memory Controller to External Memory Controller */
+	err = icc_link_create(node, TEGRA_ICC_EMC);
+	if (err)
+		goto remove_nodes;
+
+	for (i = 0; i < mc->soc->num_clients; i++) {
+		/* create MC client node */
+		node = icc_node_create(mc->soc->clients[i].id);
+		if (IS_ERR(node)) {
+			err = PTR_ERR(node);
+			goto remove_nodes;
+		}
+
+		node->name = mc->soc->clients[i].name;
+		icc_node_add(node, &mc->provider);
+
+		/* link Memory Client to Memory Controller */
+		err = icc_link_create(node, TEGRA_ICC_MC);
+		if (err)
+			goto remove_nodes;
+	}
+
+	/*
+	 * MC driver is registered too early, so early that generic driver
+	 * syncing doesn't work for the MC. But it doesn't really matter
+	 * since syncing works for the EMC drivers, hence we can sync the
+	 * MC driver by ourselves and then EMC will complete syncing of
+	 * the whole ICC state.
+	 */
+	icc_sync_state(mc->dev);
+
+	return 0;
+
+remove_nodes:
+	icc_nodes_remove(&mc->provider);
+del_provider:
+	icc_provider_del(&mc->provider);
+
+	return err;
+}
+
 static int tegra_mc_probe(struct platform_device *pdev)
 {
 	struct resource *res;
···
 	err = tegra_mc_reset_setup(mc);
 	if (err < 0)
 		dev_err(&pdev->dev, "failed to register reset controller: %d\n",
+			err);
+
+	err = tegra_mc_interconnect_setup(mc);
+	if (err < 0)
+		dev_err(&pdev->dev, "failed to initialize interconnect: %d\n",
 			err);
 
 	if (IS_ENABLED(CONFIG_TEGRA_IOMMU_SMMU) && mc->soc->smmu) {

drivers/memory/tegra/mc.h

···
 
 #define MC_TIMING_UPDATE				BIT(0)
 
+static inline u32 tegra_mc_scale_percents(u64 val, unsigned int percents)
+{
+	val = val * percents;
+	do_div(val, 100);
+
+	return min_t(u64, val, U32_MAX);
+}
+
+static inline struct tegra_mc *
+icc_provider_to_tegra_mc(struct icc_provider *provider)
+{
+	return container_of(provider, struct tegra_mc, provider);
+}
+
 static inline u32 mc_readl(struct tegra_mc *mc, unsigned long offset)
 {
 	return readl_relaxed(mc->regs + offset);
···
 #ifdef CONFIG_ARCH_TEGRA_210_SOC
 extern const struct tegra_mc_soc tegra210_mc_soc;
 #endif
+
+/*
+ * These IDs are for internal use of Tegra ICC drivers. The ID numbers are
+ * chosen such that they don't conflict with the device-tree ICC node IDs.
+ */
+#define TEGRA_ICC_MC		1000
+#define TEGRA_ICC_EMC		1001
+#define TEGRA_ICC_EMEM		1002
 
 #endif /* MEMORY_TEGRA_MC_H */

include/soc/tegra/mc.h

···
 #ifndef __SOC_TEGRA_MC_H__
 #define __SOC_TEGRA_MC_H__
 
+#include <linux/bits.h>
 #include <linux/err.h>
+#include <linux/interconnect-provider.h>
 #include <linux/reset-controller.h>
 #include <linux/types.h>
 
···
 			    const struct tegra_mc_reset *rst);
 };
 
+#define TEGRA_MC_ICC_TAG_DEFAULT				0
+#define TEGRA_MC_ICC_TAG_ISO					BIT(0)
+
+struct tegra_mc_icc_ops {
+	int (*set)(struct icc_node *src, struct icc_node *dst);
+	int (*aggregate)(struct icc_node *node, u32 tag, u32 avg_bw,
+			 u32 peak_bw, u32 *agg_avg, u32 *agg_peak);
+	struct icc_node_data *(*xlate_extended)(struct of_phandle_args *spec,
+						void *data);
+};
+
 struct tegra_mc_soc {
 	const struct tegra_mc_client *clients;
 	unsigned int num_clients;
···
 	const struct tegra_mc_reset_ops *reset_ops;
 	const struct tegra_mc_reset *resets;
 	unsigned int num_resets;
+
+	const struct tegra_mc_icc_ops *icc_ops;
 };
 
 struct tegra_mc {
···
 	unsigned int num_timings;
 
 	struct reset_controller_dev reset;
+
+	struct icc_provider provider;
 
 	spinlock_t lock;
 };