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 
setup_olpc_ofw_pgd(void)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 
__olpc_ofw(const char * name,int nr_args,const void ** args,int nr_res,void ** res)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 
olpc_ofw_present(void)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 
olpc_ofw_detect(void)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 
olpc_ofw_is_installed(void)118 bool __init olpc_ofw_is_installed(void)
119 {
120 	return olpc_ofw_cif != NULL;
121 }
122