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 */
15static int (*olpc_ofw_cif)(int *);
16
17/* page dir entry containing OFW's pgdir table; filled in by head_32.S */
18u32 olpc_ofw_pgd __initdata;
19
20static DEFINE_SPINLOCK(ofw_lock);
21
22#define MAXARGS 10
23
24void __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
47int __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}
79EXPORT_SYMBOL_GPL(__olpc_ofw);
80
81bool olpc_ofw_present(void)
82{
83	return olpc_ofw_cif != NULL;
84}
85EXPORT_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
93void __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
118bool __init olpc_ofw_is_installed(void)
119{
120	return olpc_ofw_cif != NULL;
121}
122