arc/kernel/devtree.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * Copyright (C) 2012 Synopsys, Inc. (www.synopsys.com)
0004  *
0005  * Based on reduced version of METAG
0006  */
0007
0008
0009 #include <linux/init.h>
0010 #include <linux/reboot.h>
0011 #include <linux/memblock.h>
0012 #include <linux/of.h>
0013 #include <linux/of_fdt.h>
0014 #include <asm/mach_desc.h>
0015
0016 #ifdef CONFIG_SERIAL_EARLYCON
0017
0018 static unsigned int __initdata arc_base_baud;
0019
0020 unsigned int __init arc_early_base_baud(void)
0021 {
0022     return arc_base_baud/16;
0023 }
0024
0025 static void __init arc_set_early_base_baud(unsigned long dt_root)
0026 {
0027     if (of_flat_dt_is_compatible(dt_root, "abilis,arc-tb10x"))
0028         arc_base_baud = 166666666;  /* Fixed 166.6MHz clk (TB10x) */
0029     else if (of_flat_dt_is_compatible(dt_root, "snps,arc-sdp") ||
0030          of_flat_dt_is_compatible(dt_root, "snps,hsdk"))
0031         arc_base_baud = 33333333;   /* Fixed 33MHz clk (AXS10x & HSDK) */
0032     else
0033         arc_base_baud = 50000000;   /* Fixed default 50MHz */
0034 }
0035 #else
0036 #define arc_set_early_base_baud(dt_root)
0037 #endif
0038
0039 static const void * __init arch_get_next_mach(const char *const **match)
0040 {
0041     static const struct machine_desc *mdesc = __arch_info_begin;
0042     const struct machine_desc *m = mdesc;
0043
0044     if (m >= __arch_info_end)
0045         return NULL;
0046
0047     mdesc++;
0048     *match = m->dt_compat;
0049     return m;
0050 }
0051
0052 /**
0053  * setup_machine_fdt - Machine setup when an dtb was passed to the kernel
0054  * @dt:     virtual address pointer to dt blob
0055  *
0056  * If a dtb was passed to the kernel, then use it to choose the correct
0057  * machine_desc and to setup the system.
0058  */
0059 const struct machine_desc * __init setup_machine_fdt(void *dt)
0060 {
0061     const struct machine_desc *mdesc;
0062     unsigned long dt_root;
0063
0064     if (!early_init_dt_scan(dt))
0065         return NULL;
0066
0067     mdesc = of_flat_dt_match_machine(NULL, arch_get_next_mach);
0068     if (!mdesc)
0069         machine_halt();
0070
0071     dt_root = of_get_flat_dt_root();
0072     arc_set_early_base_baud(dt_root);
0073
0074     return mdesc;
0075 }