LXR linux/arch/mips/mti-malta/malta-dtshim.c

   1/*
   2 * Copyright (C) 2015 Imagination Technologies
   3 * Author: Paul Burton <paul.burton@imgtec.com>
   4 *
   5 * This program is free software; you can redistribute it and/or modify it
   6 * under the terms of the GNU General Public License as published by the
   7 * Free Software Foundation; either version 2 of the License, or (at your
   8 * option) any later version.
   9 */
  10
  11#include <linux/bug.h>
  12#include <linux/kernel.h>
  13#include <linux/libfdt.h>
  14#include <linux/of_fdt.h>
  15#include <linux/sizes.h>
  16#include <asm/bootinfo.h>
  17#include <asm/fw/fw.h>
  18#include <asm/page.h>
  19
  20static unsigned char fdt_buf[16 << 10] __initdata;
  21
  22/* determined physical memory size, not overridden by command line args  */
  23extern unsigned long physical_memsize;
  24
  25#define MAX_MEM_ARRAY_ENTRIES 1
  26
  27static unsigned __init gen_fdt_mem_array(__be32 *mem_array, unsigned long size)
  28{
  29        unsigned long size_preio;
  30        unsigned entries;
  31
  32        entries = 1;
  33        mem_array[0] = cpu_to_be32(PHYS_OFFSET);
  34        if (config_enabled(CONFIG_EVA)) {
  35                /*
  36                 * The current Malta EVA configuration is "special" in that it
  37                 * always makes use of addresses in the upper half of the 32 bit
  38                 * physical address map, which gives it a contiguous region of
  39                 * DDR but limits it to 2GB.
  40                 */
  41                mem_array[1] = cpu_to_be32(size);
  42        } else {
  43                size_preio = min_t(unsigned long, size, SZ_256M);
  44                mem_array[1] = cpu_to_be32(size_preio);
  45        }
  46
  47        BUG_ON(entries > MAX_MEM_ARRAY_ENTRIES);
  48        return entries;
  49}
  50
  51static void __init append_memory(void *fdt, int root_off)
  52{
  53        __be32 mem_array[2 * MAX_MEM_ARRAY_ENTRIES];
  54        unsigned long memsize;
  55        unsigned mem_entries;
  56        int i, err, mem_off;
  57        char *var, param_name[10], *var_names[] = {
  58                "ememsize", "memsize",
  59        };
  60
  61        /* if a memory node already exists, leave it alone */
  62        mem_off = fdt_path_offset(fdt, "/memory");
  63        if (mem_off >= 0)
  64                return;
  65
  66        /* find memory size from the bootloader environment */
  67        for (i = 0; i < ARRAY_SIZE(var_names); i++) {
  68                var = fw_getenv(var_names[i]);
  69                if (!var)
  70                        continue;
  71
  72                err = kstrtoul(var, 0, &physical_memsize);
  73                if (!err)
  74                        break;
  75
  76                pr_warn("Failed to read the '%s' env variable '%s'\n",
  77                        var_names[i], var);
  78        }
  79
  80        if (!physical_memsize) {
  81                pr_warn("The bootloader didn't provide memsize: defaulting to 32MB\n");
  82                physical_memsize = 32 << 20;
  83        }
  84
  85        if (config_enabled(CONFIG_CPU_BIG_ENDIAN)) {
  86                /*
  87                 * SOC-it swaps, or perhaps doesn't swap, when DMA'ing
  88                 * the last word of physical memory.
  89                 */
  90                physical_memsize -= PAGE_SIZE;
  91        }
  92
  93        /* default to using all available RAM */
  94        memsize = physical_memsize;
  95
  96        /* allow the user to override the usable memory */
  97        for (i = 0; i < ARRAY_SIZE(var_names); i++) {
  98                snprintf(param_name, sizeof(param_name), "%s=", var_names[i]);
  99                var = strstr(arcs_cmdline, param_name);
 100                if (!var)
 101                        continue;
 102
 103                memsize = memparse(var + strlen(param_name), NULL);
 104        }
 105
 106        /* if the user says there's more RAM than we thought, believe them */
 107        physical_memsize = max_t(unsigned long, physical_memsize, memsize);
 108
 109        /* append memory to the DT */
 110        mem_off = fdt_add_subnode(fdt, root_off, "memory");
 111        if (mem_off < 0)
 112                panic("Unable to add memory node to DT: %d", mem_off);
 113
 114        err = fdt_setprop_string(fdt, mem_off, "device_type", "memory");
 115        if (err)
 116                panic("Unable to set memory node device_type: %d", err);
 117
 118        mem_entries = gen_fdt_mem_array(mem_array, physical_memsize);
 119        err = fdt_setprop(fdt, mem_off, "reg", mem_array,
 120                          mem_entries * 2 * sizeof(mem_array[0]));
 121        if (err)
 122                panic("Unable to set memory regs property: %d", err);
 123
 124        mem_entries = gen_fdt_mem_array(mem_array, memsize);
 125        err = fdt_setprop(fdt, mem_off, "linux,usable-memory", mem_array,
 126                          mem_entries * 2 * sizeof(mem_array[0]));
 127        if (err)
 128                panic("Unable to set linux,usable-memory property: %d", err);
 129}
 130
 131void __init *malta_dt_shim(void *fdt)
 132{
 133        int root_off, len, err;
 134        const char *compat;
 135
 136        if (fdt_check_header(fdt))
 137                panic("Corrupt DT");
 138
 139        err = fdt_open_into(fdt, fdt_buf, sizeof(fdt_buf));
 140        if (err)
 141                panic("Unable to open FDT: %d", err);
 142
 143        root_off = fdt_path_offset(fdt_buf, "/");
 144        if (root_off < 0)
 145                panic("No / node in DT");
 146
 147        compat = fdt_getprop(fdt_buf, root_off, "compatible", &len);
 148        if (!compat)
 149                panic("No root compatible property in DT: %d", len);
 150
 151        /* if this isn't Malta, leave the DT alone */
 152        if (strncmp(compat, "mti,malta", len))
 153                return fdt;
 154
 155        append_memory(fdt_buf, root_off);
 156
 157        err = fdt_pack(fdt_buf);
 158        if (err)
 159                panic("Unable to pack FDT: %d\n", err);
 160
 161        return fdt_buf;
 162}
 163