lpddr4.c

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/* SPDX-License-Identifier: GPL-2.0-only */
 
#include <console/console.h>
#include <device/device.h>
#include <device/dram/lpddr4.h>
#include <memory_info.h>
#include <smbios.h>
#include <types.h>
 
enum lpddr4_speed_grade {
        LPDDR4_1333,
        LPDDR4_1600,
        LPDDR4_1866,
        LPDDR4_2133,
        LPDDR4_2400,
        LPDDR4_2666,
        LPDDR4_3200,
        LPDDR4_3733,
        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 and industry norms
 *
 * 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_1333] = {
                .min_clock_mhz = 10,
                .max_clock_mhz = 667,
                .reported_mts = 1333,
        },
        [LPDDR4_1600] = {
                .min_clock_mhz = 668,
                .max_clock_mhz = 800,
                .reported_mts = 1600
        },
        [LPDDR4_1866] = {
                .min_clock_mhz = 801,
                .max_clock_mhz = 934,
                .reported_mts = 1866,
        },
        [LPDDR4_2133] = {
                .min_clock_mhz = 935,
                .max_clock_mhz = 1067,
                .reported_mts = 2133
        },
        [LPDDR4_2400] = {
                .min_clock_mhz = 1068,
                .max_clock_mhz = 1200,
                .reported_mts = 2400
        },
        [LPDDR4_2666] = {
                .min_clock_mhz = 1201,
                .max_clock_mhz = 1333,
                .reported_mts = 2666
        },
        [LPDDR4_3200] = {
                .min_clock_mhz = 1334,
                .max_clock_mhz = 1600,
                .reported_mts = 3200
        },
        [LPDDR4_3733] = {
                .min_clock_mhz = 1601,
                .max_clock_mhz = 1867,
                .reported_mts = 3733
        },
        [LPDDR4_4266] = {
                .min_clock_mhz = 1868,
                .max_clock_mhz = 2134,
                .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, "LPDDR4 speed of %d MHz is out of range\n", speed_mhz);
        return 0;
}