arch/arc/kernel/devtree.c

   1 /*
   2  * Copyright (C) 2012 Synopsys, Inc. (www.synopsys.com)
   3  *
   4  * Based on reduced version of METAG
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10
  11
  12 #include <linux/init.h>
  13 #include <linux/reboot.h>
  14 #include <linux/memblock.h>
  15 #include <linux/of.h>
  16 #include <linux/of_fdt.h>
  17 #include <asm/mach_desc.h>
  18
  19 #ifdef CONFIG_SERIAL_EARLYCON
  20
  21 static unsigned int __initdata arc_base_baud;
  22
  23 unsigned int __init arc_early_base_baud(void)
  24 {
  25         return arc_base_baud/16;
  26 }
  27
  28 static void __init arc_set_early_base_baud(unsigned long dt_root)
  29 {
  30         if (of_flat_dt_is_compatible(dt_root, "abilis,arc-tb10x"))
  31                 arc_base_baud = 166666666;      /* Fixed 166.6MHz clk (TB10x) */
  32         else if (of_flat_dt_is_compatible(dt_root, "snps,arc-sdp"))
  33                 arc_base_baud = 33333333;       /* Fixed 33MHz clk (AXS10x) */
  34         else if (of_flat_dt_is_compatible(dt_root, "ezchip,arc-nps"))
  35                 arc_base_baud = 800000000;      /* Fixed 800MHz clk (NPS) */
  36         else
  37                 arc_base_baud = 50000000;       /* Fixed default 50MHz */
  38 }
  39 #else
  40 #define arc_set_early_base_baud(dt_root)
  41 #endif
  42
  43 static const void * __init arch_get_next_mach(const char *const **match)
  44 {
  45         static const struct machine_desc *mdesc = __arch_info_begin;
  46         const struct machine_desc *m = mdesc;
  47
  48         if (m >= __arch_info_end)
  49                 return NULL;
  50
  51         mdesc++;
  52         *match = m->dt_compat;
  53         return m;
  54 }
  55
  56 /**
  57  * setup_machine_fdt - Machine setup when an dtb was passed to the kernel
  58  * @dt:         virtual address pointer to dt blob
  59  *
  60  * If a dtb was passed to the kernel, then use it to choose the correct
  61  * machine_desc and to setup the system.
  62  */
  63 const struct machine_desc * __init setup_machine_fdt(void *dt)
  64 {
  65         const struct machine_desc *mdesc;
  66         unsigned long dt_root;
  67
  68         if (!early_init_dt_scan(dt))
  69                 return NULL;
  70
  71         mdesc = of_flat_dt_match_machine(NULL, arch_get_next_mach);
  72         if (!mdesc)
  73                 machine_halt();
  74
  75         dt_root = of_get_flat_dt_root();
  76         arc_set_early_base_baud(dt_root);
  77
  78         return mdesc;
  79 }