1 // SPDX-License-Identifier: GPL-2.0-only
2 #include <linux/kernel.h>
3 #include <linux/export.h>
4 #include <linux/spinlock_types.h>
5 #include <linux/init.h>
6 #include <linux/pgtable.h>
7 #include <asm/page.h>
8 #include <asm/setup.h>
9 #include <asm/io.h>
10 #include <asm/cpufeature.h>
11 #include <asm/special_insns.h>
12 #include <asm/olpc_ofw.h>
13
14 /* address of OFW callback interface; will be NULL if OFW isn't found */
15 static int (*olpc_ofw_cif)(int *);
16
17 /* page dir entry containing OFW's pgdir table; filled in by head_32.S */
18 u32 olpc_ofw_pgd __initdata;
19
20 static DEFINE_SPINLOCK(ofw_lock);
21
22 #define MAXARGS 10
23
24 void __init setup_olpc_ofw_pgd(void)
25 {
26 pgd_t *base, *ofw_pde;
27
28 if (!olpc_ofw_cif)
29 return;
30
31 /* fetch OFW's PDE */
32 base = early_ioremap(olpc_ofw_pgd, sizeof(olpc_ofw_pgd) * PTRS_PER_PGD);
33 if (!base) {
34 printk(KERN_ERR "failed to remap OFW's pgd - disabling OFW!\n");
35 olpc_ofw_cif = NULL;
36 return;
37 }
38 ofw_pde = &base[OLPC_OFW_PDE_NR];
39
40 /* install OFW's PDE permanently into the kernel's pgtable */
41 set_pgd(&swapper_pg_dir[OLPC_OFW_PDE_NR], *ofw_pde);
42 /* implicit optimization barrier here due to uninline function return */
43
44 early_iounmap(base, sizeof(olpc_ofw_pgd) * PTRS_PER_PGD);
45 }
46
47 int __olpc_ofw(const char *name, int nr_args, const void **args, int nr_res,
48 void **res)
49 {
50 int ofw_args[MAXARGS + 3];
51 unsigned long flags;
52 int ret, i, *p;
53
54 BUG_ON(nr_args + nr_res > MAXARGS);
55
56 if (!olpc_ofw_cif)
57 return -EIO;
58
59 ofw_args[0] = (int)name;
60 ofw_args[1] = nr_args;
61 ofw_args[2] = nr_res;
62
63 p = &ofw_args[3];
64 for (i = 0; i < nr_args; i++, p++)
65 *p = (int)args[i];
66
67 /* call into ofw */
68 spin_lock_irqsave(&ofw_lock, flags);
69 ret = olpc_ofw_cif(ofw_args);
70 spin_unlock_irqrestore(&ofw_lock, flags);
71
72 if (!ret) {
73 for (i = 0; i < nr_res; i++, p++)
74 *((int *)res[i]) = *p;
75 }
76
77 return ret;
78 }
79 EXPORT_SYMBOL_GPL(__olpc_ofw);
80
81 bool olpc_ofw_present(void)
82 {
83 return olpc_ofw_cif != NULL;
84 }
85 EXPORT_SYMBOL_GPL(olpc_ofw_present);
86
87 /* OFW cif _should_ be above this address */
88 #define OFW_MIN 0xff000000
89
90 /* OFW starts on a 1MB boundary */
91 #define OFW_BOUND (1<<20)
92
93 void __init olpc_ofw_detect(void)
94 {
95 struct olpc_ofw_header *hdr = &boot_params.olpc_ofw_header;
96 unsigned long start;
97
98 /* ensure OFW booted us by checking for "OFW " string */
99 if (hdr->ofw_magic != OLPC_OFW_SIG)
100 return;
101
102 olpc_ofw_cif = (int (*)(int *))hdr->cif_handler;
103
104 if ((unsigned long)olpc_ofw_cif < OFW_MIN) {
105 printk(KERN_ERR "OFW detected, but cif has invalid address 0x%lx - disabling.\n",
106 (unsigned long)olpc_ofw_cif);
107 olpc_ofw_cif = NULL;
108 return;
109 }
110
111 /* determine where OFW starts in memory */
112 start = round_down((unsigned long)olpc_ofw_cif, OFW_BOUND);
113 printk(KERN_INFO "OFW detected in memory, cif @ 0x%lx (reserving top %ldMB)\n",
114 (unsigned long)olpc_ofw_cif, (-start) >> 20);
115 reserve_top_address(-start);
116 }
117
118 bool __init olpc_ofw_is_installed(void)
119 {
120 return olpc_ofw_cif != NULL;
121 }
122
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