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/clk.h>
  18 #include <asm/mach_desc.h>
  19
  20 #ifdef CONFIG_SERIAL_EARLYCON
  21
  22 static unsigned int __initdata arc_base_baud;
  23
  24 unsigned int __init arc_early_base_baud(void)
  25 {
  26         return arc_base_baud/16;
  27 }
  28
  29 static void __init arc_set_early_base_baud(unsigned long dt_root)
  30 {
  31         unsigned int core_clk = arc_get_core_freq();
  32
  33         if (of_flat_dt_is_compatible(dt_root, "abilis,arc-tb10x"))
  34                 arc_base_baud = core_clk/3;
  35         else if (of_flat_dt_is_compatible(dt_root, "snps,arc-sdp"))
  36                 arc_base_baud = 33333333;       /* Fixed 33MHz clk (AXS10x) */
  37         else
  38                 arc_base_baud = core_clk;
  39 }
  40 #else
  41 #define arc_set_early_base_baud(dt_root)
  42 #endif
  43
  44 static const void * __init arch_get_next_mach(const char *const **match)
  45 {
  46         static const struct machine_desc *mdesc = __arch_info_begin;
  47         const struct machine_desc *m = mdesc;
  48
  49         if (m >= __arch_info_end)
  50                 return NULL;
  51
  52         mdesc++;
  53         *match = m->dt_compat;
  54         return m;
  55 }
  56
  57 /**
  58  * setup_machine_fdt - Machine setup when an dtb was passed to the kernel
  59  * @dt:         virtual address pointer to dt blob
  60  *
  61  * If a dtb was passed to the kernel, then use it to choose the correct
  62  * machine_desc and to setup the system.
  63  */
  64 const struct machine_desc * __init setup_machine_fdt(void *dt)
  65 {
  66         const struct machine_desc *mdesc;
  67         unsigned long dt_root;
  68         const void *clk;
  69         int len;
  70
  71         if (!early_init_dt_scan(dt))
  72                 return NULL;
  73
  74         mdesc = of_flat_dt_match_machine(NULL, arch_get_next_mach);
  75         if (!mdesc)
  76                 machine_halt();
  77
  78         dt_root = of_get_flat_dt_root();
  79         clk = of_get_flat_dt_prop(dt_root, "clock-frequency", &len);
  80         if (clk)
  81                 arc_set_core_freq(of_read_ulong(clk, len/4));
  82
  83         arc_set_early_base_baud(dt_root);
  84
  85         return mdesc;
  86 }