1 /*
2  * Copyright (C) 2015 Imagination Technologies
3  * Author: Paul Burton <paul.burton@imgtec.com>
4  *
5  * This program is free software; you can redistribute it and/or modify it
6  * under the terms of the GNU General Public License as published by the
7  * Free Software Foundation; either version 2 of the License, or (at your
8  * option) any later version.
9  */
10 
11 #include <linux/bug.h>
12 #include <linux/kernel.h>
13 #include <linux/libfdt.h>
14 #include <linux/of_fdt.h>
15 #include <linux/sizes.h>
16 #include <asm/bootinfo.h>
17 #include <asm/fw/fw.h>
18 #include <asm/page.h>
19 
20 static unsigned char fdt_buf[16 << 10] __initdata;
21 
22 /* determined physical memory size, not overridden by command line args	 */
23 extern unsigned long physical_memsize;
24 
25 #define MAX_MEM_ARRAY_ENTRIES 1
26 
27 static unsigned __init gen_fdt_mem_array(__be32 *mem_array, unsigned long size)
28 {
29 	unsigned long size_preio;
30 	unsigned entries;
31 
32 	entries = 1;
33 	mem_array[0] = cpu_to_be32(PHYS_OFFSET);
34 	if (config_enabled(CONFIG_EVA)) {
35 		/*
36 		 * The current Malta EVA configuration is "special" in that it
37 		 * always makes use of addresses in the upper half of the 32 bit
38 		 * physical address map, which gives it a contiguous region of
39 		 * DDR but limits it to 2GB.
40 		 */
41 		mem_array[1] = cpu_to_be32(size);
42 	} else {
43 		size_preio = min_t(unsigned long, size, SZ_256M);
44 		mem_array[1] = cpu_to_be32(size_preio);
45 	}
46 
47 	BUG_ON(entries > MAX_MEM_ARRAY_ENTRIES);
48 	return entries;
49 }
50 
51 static void __init append_memory(void *fdt, int root_off)
52 {
53 	__be32 mem_array[2 * MAX_MEM_ARRAY_ENTRIES];
54 	unsigned long memsize;
55 	unsigned mem_entries;
56 	int i, err, mem_off;
57 	char *var, param_name[10], *var_names[] = {
58 		"ememsize", "memsize",
59 	};
60 
61 	/* if a memory node already exists, leave it alone */
62 	mem_off = fdt_path_offset(fdt, "/memory");
63 	if (mem_off >= 0)
64 		return;
65 
66 	/* find memory size from the bootloader environment */
67 	for (i = 0; i < ARRAY_SIZE(var_names); i++) {
68 		var = fw_getenv(var_names[i]);
69 		if (!var)
70 			continue;
71 
72 		err = kstrtoul(var, 0, &physical_memsize);
73 		if (!err)
74 			break;
75 
76 		pr_warn("Failed to read the '%s' env variable '%s'\n",
77 			var_names[i], var);
78 	}
79 
80 	if (!physical_memsize) {
81 		pr_warn("The bootloader didn't provide memsize: defaulting to 32MB\n");
82 		physical_memsize = 32 << 20;
83 	}
84 
85 	if (config_enabled(CONFIG_CPU_BIG_ENDIAN)) {
86 		/*
87 		 * SOC-it swaps, or perhaps doesn't swap, when DMA'ing
88 		 * the last word of physical memory.
89 		 */
90 		physical_memsize -= PAGE_SIZE;
91 	}
92 
93 	/* default to using all available RAM */
94 	memsize = physical_memsize;
95 
96 	/* allow the user to override the usable memory */
97 	for (i = 0; i < ARRAY_SIZE(var_names); i++) {
98 		snprintf(param_name, sizeof(param_name), "%s=", var_names[i]);
99 		var = strstr(arcs_cmdline, param_name);
100 		if (!var)
101 			continue;
102 
103 		memsize = memparse(var + strlen(param_name), NULL);
104 	}
105 
106 	/* if the user says there's more RAM than we thought, believe them */
107 	physical_memsize = max_t(unsigned long, physical_memsize, memsize);
108 
109 	/* append memory to the DT */
110 	mem_off = fdt_add_subnode(fdt, root_off, "memory");
111 	if (mem_off < 0)
112 		panic("Unable to add memory node to DT: %d", mem_off);
113 
114 	err = fdt_setprop_string(fdt, mem_off, "device_type", "memory");
115 	if (err)
116 		panic("Unable to set memory node device_type: %d", err);
117 
118 	mem_entries = gen_fdt_mem_array(mem_array, physical_memsize);
119 	err = fdt_setprop(fdt, mem_off, "reg", mem_array,
120 			  mem_entries * 2 * sizeof(mem_array[0]));
121 	if (err)
122 		panic("Unable to set memory regs property: %d", err);
123 
124 	mem_entries = gen_fdt_mem_array(mem_array, memsize);
125 	err = fdt_setprop(fdt, mem_off, "linux,usable-memory", mem_array,
126 			  mem_entries * 2 * sizeof(mem_array[0]));
127 	if (err)
128 		panic("Unable to set linux,usable-memory property: %d", err);
129 }
130 
131 void __init *malta_dt_shim(void *fdt)
132 {
133 	int root_off, len, err;
134 	const char *compat;
135 
136 	if (fdt_check_header(fdt))
137 		panic("Corrupt DT");
138 
139 	err = fdt_open_into(fdt, fdt_buf, sizeof(fdt_buf));
140 	if (err)
141 		panic("Unable to open FDT: %d", err);
142 
143 	root_off = fdt_path_offset(fdt_buf, "/");
144 	if (root_off < 0)
145 		panic("No / node in DT");
146 
147 	compat = fdt_getprop(fdt_buf, root_off, "compatible", &len);
148 	if (!compat)
149 		panic("No root compatible property in DT: %d", len);
150 
151 	/* if this isn't Malta, leave the DT alone */
152 	if (strncmp(compat, "mti,malta", len))
153 		return fdt;
154 
155 	append_memory(fdt_buf, root_off);
156 
157 	err = fdt_pack(fdt_buf);
158 	if (err)
159 		panic("Unable to pack FDT: %d\n", err);
160 
161 	return fdt_buf;
162 }
163