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
  20 static unsigned char fdt_buf[16 << 10] __initdata;
  21
  22 /* determined physical memory size, not overridden by command line args  */
  23 extern unsigned long physical_memsize;
  24
  25 #define MAX_MEM_ARRAY_ENTRIES 1
  26
  27 static 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
  51 static 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
 131 void __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 }