memory: tegra: Add EMC scaling support code for Tegra210

This is the initial patch for Tegra210 EMC frequency scaling. It has the
code to program various aspects of the EMC that are standardized, but it
does not yet include the specific programming sequence needed for clock
scaling.

The driver is designed to support LPDDR4 SDRAM. Devices that use LPDDR4
need to perform training of the RAM before it can be used. Firmware will
perform this training during early boot and pass a table of supported
frequencies to the kernel via device tree.

For the frequencies above 800 MHz, periodic retraining is needed to
compensate for changes in timing. This periodic training will have to be
performed until the frequency drops back to or below 800 MHz.

This driver provides helpers used during this runtime retraining that
will be used by the sequence specific code in a follow-up patch.

Based on work by Peter De Schrijver <pdeschrijver@nvidia.com>.
Signed-off-by: Joseph Lo <josephl@nvidia.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>

drivers/memory/tegra/Kconfig

@@ -36,3 +36,17 @@ config TEGRA124_EMC
 	  Tegra124 chips. The EMC controls the external DRAM on the board.
 	  This driver is required to change memory timings / clock rate for
 	  external memory.
+
+config TEGRA210_EMC_TABLE
+	bool
+	depends on ARCH_TEGRA_210_SOC
+
+config TEGRA210_EMC
+	tristate "NVIDIA Tegra210 External Memory Controller driver"
+	depends on TEGRA_MC && ARCH_TEGRA_210_SOC
+	select TEGRA210_EMC_TABLE
+	help
+	  This driver is for the External Memory Controller (EMC) found on
+	  Tegra210 chips. The EMC controls the external DRAM on the board.
+	  This driver is required to change memory timings / clock rate for
+	  external memory.

drivers/memory/tegra/Makefile

@@ -13,5 +13,9 @@ obj-$(CONFIG_TEGRA_MC) += tegra-mc.o
 obj-$(CONFIG_TEGRA20_EMC)  += tegra20-emc.o
 obj-$(CONFIG_TEGRA30_EMC)  += tegra30-emc.o
 obj-$(CONFIG_TEGRA124_EMC) += tegra124-emc.o
+obj-$(CONFIG_TEGRA210_EMC_TABLE) += tegra210-emc-table.o
+obj-$(CONFIG_TEGRA210_EMC) += tegra210-emc.o
 obj-$(CONFIG_ARCH_TEGRA_186_SOC) += tegra186.o tegra186-emc.o
 obj-$(CONFIG_ARCH_TEGRA_194_SOC) += tegra186.o tegra186-emc.o
+
+tegra210-emc-y := tegra210-emc-core.o

drivers/memory/tegra/mc.h

@@ -34,6 +34,7 @@
 #define MC_EMEM_ARB_TIMING_W2W				0xbc
 #define MC_EMEM_ARB_TIMING_R2W				0xc0
 #define MC_EMEM_ARB_TIMING_W2R				0xc4
+#define MC_EMEM_ARB_MISC2				0xc8
 #define MC_EMEM_ARB_DA_TURNS				0xd0
 #define MC_EMEM_ARB_DA_COVERS				0xd4
 #define MC_EMEM_ARB_MISC0				0xd8

drivers/memory/tegra/tegra210-emc-table.c

+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2020, NVIDIA CORPORATION.  All rights reserved.
+ */
+
+#include <linux/of_reserved_mem.h>
+
+#include "tegra210-emc.h"
+
+#define TEGRA_EMC_MAX_FREQS		16
+
+static int tegra210_emc_table_device_init(struct reserved_mem *rmem,
+					  struct device *dev)
+{
+	struct tegra210_emc *emc = dev_get_drvdata(dev);
+	unsigned int i;
+
+	emc->timings = memremap(rmem->base, rmem->size, MEMREMAP_WB);
+	if (!emc->timings) {
+		dev_err(dev, "failed to map EMC table\n");
+		return -ENOMEM;
+	}
+
+	emc->num_timings = 0;
+
+	for (i = 0; i < TEGRA_EMC_MAX_FREQS; i++) {
+		if (emc->timings[i].revision == 0)
+			break;
+
+		emc->num_timings++;
+	}
+
+	return 0;
+}
+
+static void tegra210_emc_table_device_release(struct reserved_mem *rmem,
+					      struct device *dev)
+{
+	struct tegra210_emc *emc = dev_get_drvdata(dev);
+
+	memunmap(emc->timings);
+}
+
+static const struct reserved_mem_ops tegra210_emc_table_ops = {
+	.device_init = tegra210_emc_table_device_init,
+	.device_release = tegra210_emc_table_device_release,
+};
+
+static int tegra210_emc_table_init(struct reserved_mem *rmem)
+{
+	pr_debug("Tegra210 EMC table at %pa, size %lu bytes\n", &rmem->base,
+		 (unsigned long)rmem->size);
+
+	rmem->ops = &tegra210_emc_table_ops;
+
+	return 0;
+}
+RESERVEDMEM_OF_DECLARE(tegra210_emc_table, "nvidia,tegra210-emc-table",
+		       tegra210_emc_table_init);

drivers/memory/tegra/tegra210-mc.h

+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (c) 2015-2020, NVIDIA CORPORATION.  All rights reserved.
+ */
+
+#ifndef TEGRA210_MC_H
+#define TEGRA210_MC_H
+
+#include "mc.h"
+
+/* register definitions */
+#define MC_LATENCY_ALLOWANCE_AVPC_0				0x2e4
+#define MC_LATENCY_ALLOWANCE_HC_0				0x310
+#define MC_LATENCY_ALLOWANCE_HC_1				0x314
+#define MC_LATENCY_ALLOWANCE_MPCORE_0				0x320
+#define MC_LATENCY_ALLOWANCE_NVENC_0				0x328
+#define MC_LATENCY_ALLOWANCE_PPCS_0				0x344
+#define MC_LATENCY_ALLOWANCE_PPCS_1				0x348
+#define MC_LATENCY_ALLOWANCE_ISP2_0				0x370
+#define MC_LATENCY_ALLOWANCE_ISP2_1				0x374
+#define MC_LATENCY_ALLOWANCE_XUSB_0				0x37c
+#define MC_LATENCY_ALLOWANCE_XUSB_1				0x380
+#define MC_LATENCY_ALLOWANCE_TSEC_0				0x390
+#define MC_LATENCY_ALLOWANCE_VIC_0				0x394
+#define MC_LATENCY_ALLOWANCE_VI2_0				0x398
+#define MC_LATENCY_ALLOWANCE_GPU_0				0x3ac
+#define MC_LATENCY_ALLOWANCE_SDMMCA_0				0x3b8
+#define MC_LATENCY_ALLOWANCE_SDMMCAA_0				0x3bc
+#define MC_LATENCY_ALLOWANCE_SDMMC_0				0x3c0
+#define MC_LATENCY_ALLOWANCE_SDMMCAB_0				0x3c4
+#define MC_LATENCY_ALLOWANCE_GPU2_0				0x3e8
+#define MC_LATENCY_ALLOWANCE_NVDEC_0				0x3d8
+#define MC_MLL_MPCORER_PTSA_RATE				0x44c
+#define MC_FTOP_PTSA_RATE					0x50c
+#define MC_EMEM_ARB_TIMING_RFCPB				0x6c0
+#define MC_EMEM_ARB_TIMING_CCDMW				0x6c4
+#define MC_EMEM_ARB_REFPB_HP_CTRL				0x6f0
+#define MC_EMEM_ARB_REFPB_BANK_CTRL				0x6f4
+#define MC_PTSA_GRANT_DECREMENT					0x960
+#define MC_EMEM_ARB_DHYST_CTRL					0xbcc
+#define MC_EMEM_ARB_DHYST_TIMEOUT_UTIL_0			0xbd0
+#define MC_EMEM_ARB_DHYST_TIMEOUT_UTIL_1			0xbd4
+#define MC_EMEM_ARB_DHYST_TIMEOUT_UTIL_2			0xbd8
+#define MC_EMEM_ARB_DHYST_TIMEOUT_UTIL_3			0xbdc
+#define MC_EMEM_ARB_DHYST_TIMEOUT_UTIL_4			0xbe0
+#define MC_EMEM_ARB_DHYST_TIMEOUT_UTIL_5			0xbe4
+#define MC_EMEM_ARB_DHYST_TIMEOUT_UTIL_6			0xbe8
+#define MC_EMEM_ARB_DHYST_TIMEOUT_UTIL_7			0xbec
+
+#endif