[PATCH v2 2/7] memory: tegra: Implement EMEM regs and ICC ops for Tegra114

[Svyatoslav Ryhel <clamor95@gmail.com>]

Prepare Internal Memory Controller for introduction of External Memory
Controller.

Signed-off-by: Svyatoslav Ryhel <clamor95@gmail.com>
Reviewed-by: Mikko Perttunen <mperttunen@nvidia.com>
---
 drivers/memory/tegra/tegra114.c | 193 ++++++++++++++++++++++++++++++++
 1 file changed, 193 insertions(+)

diff --git a/drivers/memory/tegra/tegra114.c b/drivers/memory/tegra/tegra114.c
index 02dd4e26288a..2cb153091228 100644
--- a/drivers/memory/tegra/tegra114.c
+++ b/drivers/memory/tegra/tegra114.c
@@ -3,6 +3,7 @@
  * Copyright (C) 2014-2026 NVIDIA CORPORATION.  All rights reserved.
  */
 
+#include <linux/device.h>
 #include <linux/of.h>
 #include <linux/mm.h>
 
@@ -1101,6 +1102,195 @@ static const struct tegra_mc_reset tegra114_mc_resets[] = {
 	TEGRA114_MC_RESET(VI,       0x200, 0x204, 17),
 };
 
+static void tegra114_mc_tune_client_latency(struct tegra_mc *mc,
+					    const struct tegra_mc_client *client,
+					    unsigned int bandwidth_mbytes_sec)
+{
+	u32 arb_tolerance_compensation_nsec, arb_tolerance_compensation_div;
+	unsigned int fifo_size = client->fifo_size;
+	u32 arb_nsec, la_ticks, value;
+
+	/* see 20.3.1.1 Client Configuration in Tegra4 TRM v01p */
+	if (bandwidth_mbytes_sec)
+		arb_nsec = fifo_size * NSEC_PER_USEC / bandwidth_mbytes_sec;
+	else
+		arb_nsec = U32_MAX;
+
+	/*
+	 * Latency allowness should be set with consideration for the module's
+	 * latency tolerance and internal buffering capabilities.
+	 *
+	 * Display memory clients use isochronous transfers and have very low
+	 * tolerance to a belated transfers. Hence we need to compensate the
+	 * memory arbitration imperfection for them in order to prevent FIFO
+	 * underflow condition when memory bus is busy.
+	 *
+	 * VI clients also need a stronger compensation.
+	 */
+	switch (client->swgroup) {
+	case TEGRA_SWGROUP_MPCORE:
+	case TEGRA_SWGROUP_PTC:
+		/*
+		 * We always want lower latency for these clients, hence
+		 * don't touch them.
+		 */
+		return;
+
+	case TEGRA_SWGROUP_DC:
+	case TEGRA_SWGROUP_DCB:
+		arb_tolerance_compensation_nsec = 1050;
+		arb_tolerance_compensation_div = 2;
+		break;
+
+	case TEGRA_SWGROUP_VI:
+		arb_tolerance_compensation_nsec = 1050;
+		arb_tolerance_compensation_div = 1;
+		break;
+
+	default:
+		arb_tolerance_compensation_nsec = 150;
+		arb_tolerance_compensation_div = 1;
+		break;
+	}
+
+	if (arb_nsec > arb_tolerance_compensation_nsec)
+		arb_nsec -= arb_tolerance_compensation_nsec;
+	else
+		arb_nsec = 0;
+
+	arb_nsec /= arb_tolerance_compensation_div;
+
+	/*
+	 * Latency allowance is a number of ticks a request from a particular
+	 * client may wait in the EMEM arbiter before it becomes a high-priority
+	 * request.
+	 */
+	la_ticks = arb_nsec / mc->tick;
+	la_ticks = min(la_ticks, client->regs.la.mask);
+
+	value = mc_readl(mc, client->regs.la.reg);
+	value &= ~(client->regs.la.mask << client->regs.la.shift);
+	value |= la_ticks << client->regs.la.shift;
+	mc_writel(mc, value, client->regs.la.reg);
+}
+
+static int tegra114_mc_icc_set(struct icc_node *src, struct icc_node *dst)
+{
+	struct tegra_mc *mc = icc_provider_to_tegra_mc(src->provider);
+	const struct tegra_mc_client *client = &mc->soc->clients[src->id];
+	u64 peak_bandwidth = icc_units_to_bps(src->peak_bw);
+
+	/*
+	 * Skip pre-initialization that is done by icc_node_add(), which sets
+	 * bandwidth to maximum for all clients before drivers are loaded.
+	 *
+	 * This doesn't make sense for us because we don't have drivers for all
+	 * clients and it's okay to keep configuration left from bootloader
+	 * during boot, at least for today.
+	 */
+	if (src == dst)
+		return 0;
+
+	/* convert bytes/sec to megabytes/sec */
+	do_div(peak_bandwidth, 1000000);
+
+	tegra114_mc_tune_client_latency(mc, client, peak_bandwidth);
+
+	return 0;
+}
+
+static int tegra114_mc_icc_aggreate(struct icc_node *node, u32 tag, u32 avg_bw,
+				    u32 peak_bw, u32 *agg_avg, u32 *agg_peak)
+{
+	/*
+	 * ISO clients need to reserve extra bandwidth up-front because
+	 * there could be high bandwidth pressure during initial filling
+	 * of the client's FIFO buffers.  Secondly, we need to take into
+	 * account impurities of the memory subsystem.
+	 */
+	if (tag & TEGRA_MC_ICC_TAG_ISO)
+		peak_bw = tegra_mc_scale_percents(peak_bw, 400);
+
+	*agg_avg += avg_bw;
+	*agg_peak = max(*agg_peak, peak_bw);
+
+	return 0;
+}
+
+static struct icc_node_data *
+tegra114_mc_of_icc_xlate_extended(const struct of_phandle_args *spec, void *data)
+{
+	struct tegra_mc *mc = icc_provider_to_tegra_mc(data);
+	const struct tegra_mc_client *client;
+	unsigned int i, idx = spec->args[0];
+	struct icc_node_data *ndata;
+	struct icc_node *node;
+
+	list_for_each_entry(node, &mc->provider.nodes, node_list) {
+		if (node->id != idx)
+			continue;
+
+		ndata = kzalloc_obj(*ndata);
+		if (!ndata)
+			return ERR_PTR(-ENOMEM);
+
+		client = &mc->soc->clients[idx];
+		ndata->node = node;
+
+		switch (client->swgroup) {
+		case TEGRA_SWGROUP_DC:
+		case TEGRA_SWGROUP_DCB:
+		case TEGRA_SWGROUP_PTC:
+		case TEGRA_SWGROUP_VI:
+			/* these clients are isochronous by default */
+			ndata->tag = TEGRA_MC_ICC_TAG_ISO;
+			break;
+
+		default:
+			ndata->tag = TEGRA_MC_ICC_TAG_DEFAULT;
+			break;
+		}
+
+		return ndata;
+	}
+
+	for (i = 0; i < mc->soc->num_clients; i++) {
+		if (mc->soc->clients[i].id == idx)
+			return ERR_PTR(-EPROBE_DEFER);
+	}
+
+	dev_err(mc->dev, "invalid ICC client ID %u\n", idx);
+
+	return ERR_PTR(-EINVAL);
+}
+
+static const struct tegra_mc_icc_ops tegra114_mc_icc_ops = {
+	.xlate_extended = tegra114_mc_of_icc_xlate_extended,
+	.aggregate = tegra114_mc_icc_aggreate,
+	.set = tegra114_mc_icc_set,
+};
+
+static const unsigned long tegra114_mc_emem_regs[] = {
+	MC_EMEM_ARB_CFG,
+	MC_EMEM_ARB_OUTSTANDING_REQ,
+	MC_EMEM_ARB_TIMING_RCD,
+	MC_EMEM_ARB_TIMING_RP,
+	MC_EMEM_ARB_TIMING_RC,
+	MC_EMEM_ARB_TIMING_RAS,
+	MC_EMEM_ARB_TIMING_FAW,
+	MC_EMEM_ARB_TIMING_RRD,
+	MC_EMEM_ARB_TIMING_RAP2PRE,
+	MC_EMEM_ARB_TIMING_WAP2PRE,
+	MC_EMEM_ARB_TIMING_R2R,
+	MC_EMEM_ARB_TIMING_W2W,
+	MC_EMEM_ARB_TIMING_R2W,
+	MC_EMEM_ARB_TIMING_W2R,
+	MC_EMEM_ARB_DA_TURNS,
+	MC_EMEM_ARB_DA_COVERS,
+	MC_EMEM_ARB_MISC0,
+	MC_EMEM_ARB_RING1_THROTTLE,
+};
+
 static const struct tegra_mc_intmask tegra114_mc_intmasks[] = {
 	{
 		.reg = MC_INTMASK,
@@ -1116,11 +1306,14 @@ const struct tegra_mc_soc tegra114_mc_soc = {
 	.atom_size = 32,
 	.client_id_mask = 0x7f,
 	.smmu = &tegra114_smmu_soc,
+	.emem_regs = tegra114_mc_emem_regs,
+	.num_emem_regs = ARRAY_SIZE(tegra114_mc_emem_regs),
 	.intmasks = tegra114_mc_intmasks,
 	.num_intmasks = ARRAY_SIZE(tegra114_mc_intmasks),
 	.reset_ops = &tegra_mc_reset_ops_common,
 	.resets = tegra114_mc_resets,
 	.num_resets = ARRAY_SIZE(tegra114_mc_resets),
+	.icc_ops = &tegra114_mc_icc_ops,
 	.ops = &tegra30_mc_ops,
 	.regs = &tegra20_mc_regs,
 	.handle_irq = tegra30_mc_irq_handlers,
-- 
2.51.0