xref: /openbmc/linux/arch/arc/kernel/devtree.c (revision 9be08a27)
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 		 of_flat_dt_is_compatible(dt_root, "snps,hsdk"))
34 		arc_base_baud = 33333333;	/* Fixed 33MHz clk (AXS10x & HSDK) */
35 	else if (of_flat_dt_is_compatible(dt_root, "ezchip,arc-nps"))
36 		arc_base_baud = 800000000;      /* Fixed 800MHz clk (NPS) */
37 	else
38 		arc_base_baud = 50000000;	/* Fixed default 50MHz */
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 
69 	if (!early_init_dt_scan(dt))
70 		return NULL;
71 
72 	mdesc = of_flat_dt_match_machine(NULL, arch_get_next_mach);
73 	if (!mdesc)
74 		machine_halt();
75 
76 	dt_root = of_get_flat_dt_root();
77 	arc_set_early_base_baud(dt_root);
78 
79 	return mdesc;
80 }
81