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/spinlock.h>
14 #include <linux/types.h>
15
16 #include <asm/machdep.h>
17 #include <asm/nvram.h>
18 #include <asm/prom.h>
19
20 static void __iomem *mmio_nvram_start;
21 static long mmio_nvram_len;
22 static DEFINE_SPINLOCK(mmio_nvram_lock);
23
mmio_nvram_read(char * buf,size_t count,loff_t * index)24 static 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
mmio_nvram_read_val(int addr)43 static 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
mmio_nvram_write(char * buf,size_t count,loff_t * index)60 static 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
mmio_nvram_write_val(int addr,unsigned char val)79 static 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
mmio_nvram_get_size(void)92 static ssize_t mmio_nvram_get_size(void)
93 {
94 return mmio_nvram_len;
95 }
96
mmio_nvram_init(void)97 int __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
142 out:
143 of_node_put(nvram_node);
144 return ret;
145 }
146