1 /*
2  *  c 2001 PPC 64 Team, IBM Corp
3  *
4  *      This program is free software; you can redistribute it and/or
5  *      modify it under the terms of the GNU General Public License
6  *      as published by the Free Software Foundation; either version
7  *      2 of the License, or (at your option) any later version.
8  *
9  * /dev/nvram driver for PPC64
10  *
11  * This perhaps should live in drivers/char
12  */
13 
14 
15 #include <linux/types.h>
16 #include <linux/errno.h>
17 #include <linux/init.h>
18 #include <linux/slab.h>
19 #include <linux/spinlock.h>
20 #include <asm/uaccess.h>
21 #include <asm/nvram.h>
22 #include <asm/rtas.h>
23 #include <asm/prom.h>
24 #include <asm/machdep.h>
25 
26 static unsigned int nvram_size;
27 static int nvram_fetch, nvram_store;
28 static char nvram_buf[NVRW_CNT];	/* assume this is in the first 4GB */
29 static DEFINE_SPINLOCK(nvram_lock);
30 
31 
32 static ssize_t pSeries_nvram_read(char *buf, size_t count, loff_t *index)
33 {
34 	unsigned int i;
35 	unsigned long len;
36 	int done;
37 	unsigned long flags;
38 	char *p = buf;
39 
40 
41 	if (nvram_size == 0 || nvram_fetch == RTAS_UNKNOWN_SERVICE)
42 		return -ENODEV;
43 
44 	if (*index >= nvram_size)
45 		return 0;
46 
47 	i = *index;
48 	if (i + count > nvram_size)
49 		count = nvram_size - i;
50 
51 	spin_lock_irqsave(&nvram_lock, flags);
52 
53 	for (; count != 0; count -= len) {
54 		len = count;
55 		if (len > NVRW_CNT)
56 			len = NVRW_CNT;
57 
58 		if ((rtas_call(nvram_fetch, 3, 2, &done, i, __pa(nvram_buf),
59 			       len) != 0) || len != done) {
60 			spin_unlock_irqrestore(&nvram_lock, flags);
61 			return -EIO;
62 		}
63 
64 		memcpy(p, nvram_buf, len);
65 
66 		p += len;
67 		i += len;
68 	}
69 
70 	spin_unlock_irqrestore(&nvram_lock, flags);
71 
72 	*index = i;
73 	return p - buf;
74 }
75 
76 static ssize_t pSeries_nvram_write(char *buf, size_t count, loff_t *index)
77 {
78 	unsigned int i;
79 	unsigned long len;
80 	int done;
81 	unsigned long flags;
82 	const char *p = buf;
83 
84 	if (nvram_size == 0 || nvram_store == RTAS_UNKNOWN_SERVICE)
85 		return -ENODEV;
86 
87 	if (*index >= nvram_size)
88 		return 0;
89 
90 	i = *index;
91 	if (i + count > nvram_size)
92 		count = nvram_size - i;
93 
94 	spin_lock_irqsave(&nvram_lock, flags);
95 
96 	for (; count != 0; count -= len) {
97 		len = count;
98 		if (len > NVRW_CNT)
99 			len = NVRW_CNT;
100 
101 		memcpy(nvram_buf, p, len);
102 
103 		if ((rtas_call(nvram_store, 3, 2, &done, i, __pa(nvram_buf),
104 			       len) != 0) || len != done) {
105 			spin_unlock_irqrestore(&nvram_lock, flags);
106 			return -EIO;
107 		}
108 
109 		p += len;
110 		i += len;
111 	}
112 	spin_unlock_irqrestore(&nvram_lock, flags);
113 
114 	*index = i;
115 	return p - buf;
116 }
117 
118 static ssize_t pSeries_nvram_get_size(void)
119 {
120 	return nvram_size ? nvram_size : -ENODEV;
121 }
122 
123 int __init pSeries_nvram_init(void)
124 {
125 	struct device_node *nvram;
126 	const unsigned int *nbytes_p;
127 	unsigned int proplen;
128 
129 	nvram = of_find_node_by_type(NULL, "nvram");
130 	if (nvram == NULL)
131 		return -ENODEV;
132 
133 	nbytes_p = of_get_property(nvram, "#bytes", &proplen);
134 	if (nbytes_p == NULL || proplen != sizeof(unsigned int))
135 		return -EIO;
136 
137 	nvram_size = *nbytes_p;
138 
139 	nvram_fetch = rtas_token("nvram-fetch");
140 	nvram_store = rtas_token("nvram-store");
141 	printk(KERN_INFO "PPC64 nvram contains %d bytes\n", nvram_size);
142 	of_node_put(nvram);
143 
144 	ppc_md.nvram_read	= pSeries_nvram_read;
145 	ppc_md.nvram_write	= pSeries_nvram_write;
146 	ppc_md.nvram_size	= pSeries_nvram_get_size;
147 
148 	return 0;
149 }
150