// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (C) 2016 Imagination Technologies
 * Author: Paul Burton <paul.burton@mips.com>
 */

#define pr_fmt(fmt) "yamon-dt: " fmt

#include <linux/bug.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/libfdt.h>
#include <linux/printk.h>

#include <asm/fw/fw.h>
#include <asm/yamon-dt.h>

#define MAX_MEM_ARRAY_ENTRIES   2

__init int yamon_dt_append_cmdline(void *fdt)
{
        int err, chosen_off;

        /* find or add chosen node */
        chosen_off = fdt_path_offset(fdt, "/chosen");
        if (chosen_off == -FDT_ERR_NOTFOUND)
                chosen_off = fdt_add_subnode(fdt, 0, "chosen");
        if (chosen_off < 0) {
                pr_err("Unable to find or add DT chosen node: %d\n",
                       chosen_off);
                return chosen_off;
        }

        err = fdt_setprop_string(fdt, chosen_off, "bootargs", fw_getcmdline());
        if (err) {
                pr_err("Unable to set bootargs property: %d\n", err);
                return err;
        }

        return 0;
}

static unsigned int __init gen_fdt_mem_array(
                                        const struct yamon_mem_region *regions,
                                        __be32 *mem_array,
                                        unsigned int max_entries,
                                        unsigned long memsize)
{
        const struct yamon_mem_region *mr;
        unsigned long size;
        unsigned int entries = 0;

        for (mr = regions; mr->size && memsize; ++mr) {
                if (entries >= max_entries) {
                        pr_warn("Number of regions exceeds max %u\n",
                                max_entries);
                        break;
                }

                /* How much of the remaining RAM fits in the next region? */
                size = min_t(unsigned long, memsize, mr->size);
                memsize -= size;

                /* Emit a memory region */
                *(mem_array++) = cpu_to_be32(mr->start);
                *(mem_array++) = cpu_to_be32(size);
                ++entries;

                /* Discard the next mr->discard bytes */
                memsize -= min_t(unsigned long, memsize, mr->discard);
        }
        return entries;
}

__init int yamon_dt_append_memory(void *fdt,
                                  const struct yamon_mem_region *regions)
{
        unsigned long phys_memsize = 0, memsize;
        __be32 mem_array[2 * MAX_MEM_ARRAY_ENTRIES];
        unsigned int mem_entries;
        int i, err, mem_off;
        char *var, param_name[10], *var_names[] = {
                "ememsize", "memsize",
        };

        /* find memory size from the bootloader environment */
        for (i = 0; i < ARRAY_SIZE(var_names); i++) {
                var = fw_getenv(var_names[i]);
                if (!var)
                        continue;

                err = kstrtoul(var, 0, &phys_memsize);
                if (!err)
                        break;

                pr_warn("Failed to read the '%s' env variable '%s'\n",
                        var_names[i], var);
        }

        if (!phys_memsize) {
                pr_warn("The bootloader didn't provide memsize: defaulting to 32MB\n");
                phys_memsize = 32 << 20;
        }

        /* default to using all available RAM */
        memsize = phys_memsize;

        /* allow the user to override the usable memory */
        for (i = 0; i < ARRAY_SIZE(var_names); i++) {
                snprintf(param_name, sizeof(param_name), "%s=", var_names[i]);
                var = strstr(arcs_cmdline, param_name);
                if (!var)
                        continue;

                memsize = memparse(var + strlen(param_name), NULL);
        }

        /* if the user says there's more RAM than we thought, believe them */
        phys_memsize = max_t(unsigned long, phys_memsize, memsize);

        /* find or add a memory node */
        mem_off = fdt_path_offset(fdt, "/memory");
        if (mem_off == -FDT_ERR_NOTFOUND)
                mem_off = fdt_add_subnode(fdt, 0, "memory");
        if (mem_off < 0) {
                pr_err("Unable to find or add memory DT node: %d\n", mem_off);
                return mem_off;
        }

        err = fdt_setprop_string(fdt, mem_off, "device_type", "memory");
        if (err) {
                pr_err("Unable to set memory node device_type: %d\n", err);
                return err;
        }

        mem_entries = gen_fdt_mem_array(regions, mem_array,
                                        MAX_MEM_ARRAY_ENTRIES, phys_memsize);
        err = fdt_setprop(fdt, mem_off, "reg",
                          mem_array, mem_entries * 2 * sizeof(mem_array[0]));
        if (err) {
                pr_err("Unable to set memory regs property: %d\n", err);
                return err;
        }

        mem_entries = gen_fdt_mem_array(regions, mem_array,
                                        MAX_MEM_ARRAY_ENTRIES, memsize);
        err = fdt_setprop(fdt, mem_off, "linux,usable-memory",
                          mem_array, mem_entries * 2 * sizeof(mem_array[0]));
        if (err) {
                pr_err("Unable to set linux,usable-memory property: %d\n", err);
                return err;
        }

        return 0;
}

__init int yamon_dt_serial_config(void *fdt)
{
        const char *yamontty, *mode_var;
        char mode_var_name[9], path[20], parity;
        unsigned int uart, baud, stop_bits;
        bool hw_flow;
        int chosen_off, err;

        yamontty = fw_getenv("yamontty");
        if (!yamontty || !strcmp(yamontty, "tty0")) {
                uart = 0;
        } else if (!strcmp(yamontty, "tty1")) {
                uart = 1;
        } else {
                pr_warn("yamontty environment variable '%s' invalid\n",
                        yamontty);
                uart = 0;
        }

        baud = stop_bits = 0;
        parity = 0;
        hw_flow = false;

        snprintf(mode_var_name, sizeof(mode_var_name), "modetty%u", uart);
        mode_var = fw_getenv(mode_var_name);
        if (mode_var) {
                while (mode_var[0] >= '0' && mode_var[0] <= '9') {
                        baud *= 10;
                        baud += mode_var[0] - '0';
                        mode_var++;
                }
                if (mode_var[0] == ',')
                        mode_var++;
                if (mode_var[0])
                        parity = mode_var[0];
                if (mode_var[0] == ',')
                        mode_var++;
                if (mode_var[0])
                        stop_bits = mode_var[0] - '0';
                if (mode_var[0] == ',')
                        mode_var++;
                if (!strcmp(mode_var, "hw"))
                        hw_flow = true;
        }

        if (!baud)
                baud = 38400;

        if (parity != 'e' && parity != 'n' && parity != 'o')
                parity = 'n';

        if (stop_bits != 7 && stop_bits != 8)
                stop_bits = 8;

        WARN_ON(snprintf(path, sizeof(path), "serial%u:%u%c%u%s",
                         uart, baud, parity, stop_bits,
                         hw_flow ? "r" : "") >= sizeof(path));

        /* find or add chosen node */
        chosen_off = fdt_path_offset(fdt, "/chosen");
        if (chosen_off == -FDT_ERR_NOTFOUND)
                chosen_off = fdt_add_subnode(fdt, 0, "chosen");
        if (chosen_off < 0) {
                pr_err("Unable to find or add DT chosen node: %d\n",
                       chosen_off);
                return chosen_off;
        }

        err = fdt_setprop_string(fdt, chosen_off, "stdout-path", path);
        if (err) {
                pr_err("Unable to set stdout-path property: %d\n", err);
                return err;
        }

        return 0;
}