1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * memory mapped NVRAM
4 *
5 * (C) Copyright IBM Corp. 2005
6 *
7 * Authors : Utz Bacher <utz.bacher@de.ibm.com>
8 */
9
10#include <linux/fs.h>
11#include <linux/init.h>
12#include <linux/kernel.h>
13#include <linux/of_address.h>
14#include <linux/spinlock.h>
15#include <linux/types.h>
16
17#include <asm/machdep.h>
18#include <asm/nvram.h>
19
20static void __iomem *mmio_nvram_start;
21static long mmio_nvram_len;
22static DEFINE_SPINLOCK(mmio_nvram_lock);
23
24static ssize_t mmio_nvram_read(char *buf, size_t count, loff_t *index)
25{
26	unsigned long flags;
27
28	if (*index >= mmio_nvram_len)
29		return 0;
30	if (*index + count > mmio_nvram_len)
31		count = mmio_nvram_len - *index;
32
33	spin_lock_irqsave(&mmio_nvram_lock, flags);
34
35	memcpy_fromio(buf, mmio_nvram_start + *index, count);
36
37	spin_unlock_irqrestore(&mmio_nvram_lock, flags);
38
39	*index += count;
40	return count;
41}
42
43static unsigned char mmio_nvram_read_val(int addr)
44{
45	unsigned long flags;
46	unsigned char val;
47
48	if (addr >= mmio_nvram_len)
49		return 0xff;
50
51	spin_lock_irqsave(&mmio_nvram_lock, flags);
52
53	val = ioread8(mmio_nvram_start + addr);
54
55	spin_unlock_irqrestore(&mmio_nvram_lock, flags);
56
57	return val;
58}
59
60static ssize_t mmio_nvram_write(char *buf, size_t count, loff_t *index)
61{
62	unsigned long flags;
63
64	if (*index >= mmio_nvram_len)
65		return 0;
66	if (*index + count > mmio_nvram_len)
67		count = mmio_nvram_len - *index;
68
69	spin_lock_irqsave(&mmio_nvram_lock, flags);
70
71	memcpy_toio(mmio_nvram_start + *index, buf, count);
72
73	spin_unlock_irqrestore(&mmio_nvram_lock, flags);
74
75	*index += count;
76	return count;
77}
78
79static void mmio_nvram_write_val(int addr, unsigned char val)
80{
81	unsigned long flags;
82
83	if (addr < mmio_nvram_len) {
84		spin_lock_irqsave(&mmio_nvram_lock, flags);
85
86		iowrite8(val, mmio_nvram_start + addr);
87
88		spin_unlock_irqrestore(&mmio_nvram_lock, flags);
89	}
90}
91
92static ssize_t mmio_nvram_get_size(void)
93{
94	return mmio_nvram_len;
95}
96
97int __init mmio_nvram_init(void)
98{
99	struct device_node *nvram_node;
100	unsigned long nvram_addr;
101	struct resource r;
102	int ret;
103
104	nvram_node = of_find_node_by_type(NULL, "nvram");
105	if (!nvram_node)
106		nvram_node = of_find_compatible_node(NULL, NULL, "nvram");
107	if (!nvram_node) {
108		printk(KERN_WARNING "nvram: no node found in device-tree\n");
109		return -ENODEV;
110	}
111
112	ret = of_address_to_resource(nvram_node, 0, &r);
113	if (ret) {
114		printk(KERN_WARNING "nvram: failed to get address (err %d)\n",
115		       ret);
116		goto out;
117	}
118	nvram_addr = r.start;
119	mmio_nvram_len = resource_size(&r);
120	if ( (!mmio_nvram_len) || (!nvram_addr) ) {
121		printk(KERN_WARNING "nvram: address or length is 0\n");
122		ret = -EIO;
123		goto out;
124	}
125
126	mmio_nvram_start = ioremap(nvram_addr, mmio_nvram_len);
127	if (!mmio_nvram_start) {
128		printk(KERN_WARNING "nvram: failed to ioremap\n");
129		ret = -ENOMEM;
130		goto out;
131	}
132
133	printk(KERN_INFO "mmio NVRAM, %luk at 0x%lx mapped to %p\n",
134	       mmio_nvram_len >> 10, nvram_addr, mmio_nvram_start);
135
136	ppc_md.nvram_read_val	= mmio_nvram_read_val;
137	ppc_md.nvram_write_val	= mmio_nvram_write_val;
138	ppc_md.nvram_read	= mmio_nvram_read;
139	ppc_md.nvram_write	= mmio_nvram_write;
140	ppc_md.nvram_size	= mmio_nvram_get_size;
141
142out:
143	of_node_put(nvram_node);
144	return ret;
145}
146