device/dram: Add function to convert freq to MT/s for (LP)DDR5

As the frequency field in the SMBIOS type 17 table is deprecated,
we need to provide the maximum and configured speed in MT/s. Add
a method to convert from frequency to MT/s using a lookup table.

BUG=b:239000826
TEST=Build and verify with other patches in train

Change-Id: I0402b33a667f7d72918365a6a79b13c5b1719c0d
Signed-off-by: Matt DeVillier <matt.devillier@amd.corp-partner.google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/66953
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Raul Rangel <rrangel@chromium.org>
Reviewed-by: Fred Reitberger <reitbergerfred@gmail.com>
Reviewed-by: Marshall Dawson <marshalldawson3rd@gmail.com>

src/device/dram/Makefile.inc

@@ -1,3 +1,3 @@
-romstage-y += lpddr4.c ddr4.c ddr3.c ddr2.c ddr_common.c
+romstage-y += ddr5.c lpddr4.c ddr4.c ddr3.c ddr2.c ddr_common.c
 
-ramstage-y += lpddr4.c ddr4.c ddr3.c ddr2.c ddr_common.c spd.c
+ramstage-y += ddr5.c lpddr4.c ddr4.c ddr3.c ddr2.c ddr_common.c spd.c

src/device/dram/ddr5.c

@@ -0,0 +1,128 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <console/console.h>
+#include <device/device.h>
+#include <device/dram/ddr5.h>
+#include <memory_info.h>
+#include <smbios.h>
+#include <types.h>
+
+enum ddr5_speed_grade {
+	DDR5_1333,
+	DDR5_1600,
+	DDR5_1866,
+	DDR5_2133,
+	DDR5_2400,
+	DDR5_2667,
+	DDR5_2933,
+	DDR5_3200,
+	DDR5_3733,
+	DDR5_4267,
+	DDR5_4800,
+	DDR5_5500,
+	DDR5_6000,
+	DDR5_6400,
+};
+
+struct ddr5_speed_attr {
+	uint32_t min_clock_mhz; // inclusive
+	uint32_t max_clock_mhz; // inclusive
+	uint32_t reported_mts;
+};
+
+/**
+ * (LP)DDR5 speed attributes derived from JEDEC JESD79-5B, JESD209-5B and industry norms
+ *
+ * min_clock_mhz = previous max speed + 1
+ * max_clock_mhz = 50% of speed grade, +/- 1
+ * reported_mts  = Standard reported DDR5 speed in MT/s
+ *                 May be slightly less than the actual max MT/s
+ */
+static const struct ddr5_speed_attr ddr5_speeds[] = {
+	[DDR5_1333] = {
+		.min_clock_mhz = 10,
+		.max_clock_mhz = 667,
+		.reported_mts = 1333,
+	},
+	[DDR5_1600] = {
+		.min_clock_mhz = 668,
+		.max_clock_mhz = 800,
+		.reported_mts = 1600,
+	},
+	[DDR5_1866] = {
+		.min_clock_mhz = 801,
+		.max_clock_mhz = 933,
+		.reported_mts = 1866,
+	},
+	[DDR5_2133] = {
+		.min_clock_mhz = 934,
+		.max_clock_mhz = 1067,
+		.reported_mts = 2133,
+	},
+	[DDR5_2400] = {
+		.min_clock_mhz = 1068,
+		.max_clock_mhz = 1200,
+		.reported_mts = 2400,
+	},
+	[DDR5_2667] = {
+		.min_clock_mhz = 1201,
+		.max_clock_mhz = 1333,
+		.reported_mts = 2667,
+	},
+	[DDR5_2933] = {
+		.min_clock_mhz = 1334,
+		.max_clock_mhz = 1467,
+		.reported_mts = 2933,
+	},
+	[DDR5_3200] = {
+		.min_clock_mhz = 1468,
+		.max_clock_mhz = 1600,
+		.reported_mts = 3200,
+	},
+	[DDR5_3733] = {
+		.min_clock_mhz = 1601,
+		.max_clock_mhz = 1866,
+		.reported_mts = 3733
+	},
+	[DDR5_4267] = {
+		.min_clock_mhz = 1867,
+		.max_clock_mhz = 2133,
+		.reported_mts = 4267
+	},
+	[DDR5_4800] = {
+		.min_clock_mhz = 2134,
+		.max_clock_mhz = 2400,
+		.reported_mts = 4800
+	},
+	[DDR5_5500] = {
+		.min_clock_mhz = 2401,
+		.max_clock_mhz = 2750,
+		.reported_mts = 5500
+	},
+	[DDR5_6000] = {
+		.min_clock_mhz = 2751,
+		.max_clock_mhz = 3000,
+		.reported_mts = 6000
+	},
+	[DDR5_6400] = {
+		.min_clock_mhz = 3001,
+		.max_clock_mhz = 3200,
+		.reported_mts = 6400
+	},
+};
+
+/**
+ * Converts DDR5 clock speed in MHz to the standard reported speed in MT/s
+ */
+uint16_t ddr5_speed_mhz_to_reported_mts(uint16_t speed_mhz)
+{
+	for (enum ddr5_speed_grade speed = 0; speed < ARRAY_SIZE(ddr5_speeds); speed++) {
+		const struct ddr5_speed_attr *speed_attr = &ddr5_speeds[speed];
+		if (speed_mhz >= speed_attr->min_clock_mhz &&
+		    speed_mhz <= speed_attr->max_clock_mhz) {
+			return speed_attr->reported_mts;
+		}
+	}
+	printk(BIOS_ERR, "DDR5 speed of %d MHz is out of range\n", speed_mhz);
+	return 0;
+}

src/include/device/dram/ddr5.h

@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#ifndef DEVICE_DRAM_DDR5_H
+#define DEVICE_DRAM_DDR5_H
+
+/**
+ * @file ddr5.h
+ *
+ * \brief Utilities for decoding (LP)DDR5 info
+ */
+
+#include <device/dram/common.h>
+#include <types.h>
+
+/**
+ * Converts DDR5 clock speed in MHz to the standard reported speed in MT/s
+ */
+uint16_t ddr5_speed_mhz_to_reported_mts(uint16_t speed_mhz);
+
+#endif /* DEVICE_DRAM_DDR5_H */