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 | |
20 | static void __iomem *mmio_nvram_start; |
21 | static long mmio_nvram_len; |
22 | static DEFINE_SPINLOCK(mmio_nvram_lock); |
23 | |
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(lock: &mmio_nvram_lock, flags); |
38 | |
39 | *index += count; |
40 | return count; |
41 | } |
42 | |
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(lock: &mmio_nvram_lock, flags); |
56 | |
57 | return val; |
58 | } |
59 | |
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(lock: &mmio_nvram_lock, flags); |
74 | |
75 | *index += count; |
76 | return count; |
77 | } |
78 | |
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(lock: &mmio_nvram_lock, flags); |
89 | } |
90 | } |
91 | |
92 | static ssize_t mmio_nvram_get_size(void) |
93 | { |
94 | return mmio_nvram_len; |
95 | } |
96 | |
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, type: "nvram" ); |
105 | if (!nvram_node) |
106 | nvram_node = of_find_compatible_node(NULL, NULL, compat: "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(dev: nvram_node, index: 0, r: &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(res: &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(offset: nvram_addr, size: 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(node: nvram_node); |
144 | return ret; |
145 | } |
146 | |