xref: /openbmc/linux/arch/powerpc/sysdev/mmio_nvram.c (revision e6f6390a)
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 
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