1 files changed, 70 insertions, 0 deletions
diff --git a/src/device/dram/lpddr4.c b/src/device/dram/lpddr4.c
new file mode 100644
index 0000000000..5b829f7812
--- /dev/null
+++ b/src/device/dram/lpddr4.c
@@ -0,0 +1,70 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <console/console.h>
+#include <cbmem.h>
+#include <device/device.h>
+#include <device/dram/lpddr4.h>
+#include <string.h>
+#include <memory_info.h>
+#include <smbios.h>
+#include <types.h>
+
+enum lpddr4_speed_grade {
+	LPDDR4_1600,
+	LPDDR4_2400,
+	LPDDR4_3200,
+	LPDDR4_4266
+};
+
+struct lpddr4_speed_attr {
+	uint32_t min_clock_mhz; // inclusive
+	uint32_t max_clock_mhz; // inclusive
+	uint32_t reported_mts;
+};
+
+/**
+ * LPDDR4 speed attributes derived from JEDEC 209-4C table 210
+ *
+ * min_clock_mhz = Previous max_clock_mhz + 1
+ * max_clock_mhz = 1000/min_tCk_avg(ns)
+ * reported_mts  = Standard reported DDR4 speed in MT/s
+ *                 May be slightly less than the actual max MT/s
+ */
+static const struct lpddr4_speed_attr lpddr4_speeds[] = {
+	[LPDDR4_1600] = {
+		.min_clock_mhz = 10,
+		.max_clock_mhz = 800,
+		.reported_mts = 1600
+	},
+	[LPDDR4_2400] = {
+		.min_clock_mhz = 801,
+		.max_clock_mhz = 1200,
+		.reported_mts = 2400
+	},
+	[LPDDR4_3200] = {
+		.min_clock_mhz = 1201,
+		.max_clock_mhz = 1600,
+		.reported_mts = 3200
+	},
+	[LPDDR4_4266] = {
+		.min_clock_mhz = 1601,
+		.max_clock_mhz = 2137,
+		.reported_mts = 4266
+	},
+};
+
+/**
+ * Converts LPDDR4 clock speed in MHz to the standard reported speed in MT/s
+ */
+uint16_t lpddr4_speed_mhz_to_reported_mts(uint16_t speed_mhz)
+{
+	for (enum lpddr4_speed_grade speed = 0; speed < ARRAY_SIZE(lpddr4_speeds); speed++) {
+		const struct lpddr4_speed_attr *speed_attr = &lpddr4_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, "ERROR: LPDDR4 speed of %d MHz is out of range", speed_mhz);
+	return 0;
+}