arch/arc/kernel/devtree.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2012 Synopsys, Inc. (www.synopsys.com)
   4  *
   5  * Based on reduced version of METAG
   6  */
   7
   8
   9 #include <linux/init.h>
  10 #include <linux/reboot.h>
  11 #include <linux/memblock.h>
  12 #include <linux/of.h>
  13 #include <linux/of_fdt.h>
  14 #include <asm/mach_desc.h>
  15 #include <asm/serial.h>
  16
  17 #ifdef CONFIG_SERIAL_EARLYCON
  18
  19 static unsigned int __initdata arc_base_baud;
  20
  21 unsigned int __init arc_early_base_baud(void)
  22 {
  23         return arc_base_baud/16;
  24 }
  25
  26 static void __init arc_set_early_base_baud(unsigned long dt_root)
  27 {
  28         if (of_flat_dt_is_compatible(dt_root, "abilis,arc-tb10x"))
  29                 arc_base_baud = 166666666;      /* Fixed 166.6MHz clk (TB10x) */
  30         else if (of_flat_dt_is_compatible(dt_root, "snps,arc-sdp") ||
  31                  of_flat_dt_is_compatible(dt_root, "snps,hsdk"))
  32                 arc_base_baud = 33333333;       /* Fixed 33MHz clk (AXS10x & HSDK) */
  33         else
  34                 arc_base_baud = 50000000;       /* Fixed default 50MHz */
  35 }
  36 #else
  37 #define arc_set_early_base_baud(dt_root)
  38 #endif
  39
  40 static const void * __init arch_get_next_mach(const char *const **match)
  41 {
  42         static const struct machine_desc *mdesc = __arch_info_begin;
  43         const struct machine_desc *m = mdesc;
  44
  45         if (m >= __arch_info_end)
  46                 return NULL;
  47
  48         mdesc++;
  49         *match = m->dt_compat;
  50         return m;
  51 }
  52
  53 /**
  54  * setup_machine_fdt - Machine setup when an dtb was passed to the kernel
  55  * @dt:         virtual address pointer to dt blob
  56  *
  57  * If a dtb was passed to the kernel, then use it to choose the correct
  58  * machine_desc and to setup the system.
  59  */
  60 const struct machine_desc * __init setup_machine_fdt(void *dt)
  61 {
  62         const struct machine_desc *mdesc;
  63         unsigned long dt_root;
  64
  65         if (!early_init_dt_scan(dt, __pa(dt)))
  66                 return NULL;
  67
  68         mdesc = of_flat_dt_match_machine(NULL, arch_get_next_mach);
  69         if (!mdesc)
  70                 machine_halt();
  71
  72         dt_root = of_get_flat_dt_root();
  73         arc_set_early_base_baud(dt_root);
  74
  75         return mdesc;
  76 }