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#include <linux/module.h>
15
16#include <linux/types.h>
17#include <linux/errno.h>
18#include <linux/fs.h>
19#include <linux/miscdevice.h>
20#include <linux/fcntl.h>
21#include <linux/nvram.h>
22#include <linux/init.h>
23#include <asm/uaccess.h>
24#include <asm/nvram.h>
25#include <asm/rtas.h>
26#include <asm/prom.h>
27
28static unsigned int rtas_nvram_size;
29static unsigned int nvram_fetch, nvram_store;
30static char nvram_buf[4];	/* assume this is in the first 4GB */
31
32static loff_t nvram_llseek(struct file *file, loff_t offset, int origin)
33{
34	switch (origin) {
35	case 1:
36		offset += file->f_pos;
37		break;
38	case 2:
39		offset += rtas_nvram_size;
40		break;
41	}
42	if (offset < 0)
43		return -EINVAL;
44	file->f_pos = offset;
45	return file->f_pos;
46}
47
48
49static ssize_t read_nvram(struct file *file, char *buf,
50			  size_t count, loff_t *ppos)
51{
52	unsigned int i;
53	unsigned long len;
54	char *p = buf;
55
56	if (verify_area(VERIFY_WRITE, buf, count))
57		return -EFAULT;
58	if (*ppos >= rtas_nvram_size)
59		return 0;
60	for (i = *ppos; count > 0 && i < rtas_nvram_size; ++i, ++p, --count) {
61		if ((rtas_call(nvram_fetch, 3, 2, &len, i, __pa(nvram_buf), 1) != 0) ||
62		    len != 1)
63			return -EIO;
64		if (__put_user(nvram_buf[0], p))
65			return -EFAULT;
66	}
67	*ppos = i;
68	return p - buf;
69}
70
71static ssize_t write_nvram(struct file *file, const char *buf,
72			   size_t count, loff_t *ppos)
73{
74	unsigned int i;
75	unsigned long len;
76	const char *p = buf;
77	char c;
78
79	if (verify_area(VERIFY_READ, buf, count))
80		return -EFAULT;
81	if (*ppos >= rtas_nvram_size)
82		return 0;
83	for (i = *ppos; count > 0 && i < rtas_nvram_size; ++i, ++p, --count) {
84		if (__get_user(c, p))
85			return -EFAULT;
86		nvram_buf[0] = c;
87		if ((rtas_call(nvram_store, 3, 2, &len, i, __pa(nvram_buf), 1) != 0) ||
88		    len != 1)
89			return -EIO;
90	}
91	*ppos = i;
92	return p - buf;
93}
94
95static int nvram_ioctl(struct inode *inode, struct file *file,
96	unsigned int cmd, unsigned long arg)
97{
98	return -EINVAL;
99}
100
101struct file_operations nvram_fops = {
102	owner:		THIS_MODULE,
103	llseek:		nvram_llseek,
104	read:		read_nvram,
105	write:		write_nvram,
106	ioctl:		nvram_ioctl,
107};
108
109static struct miscdevice nvram_dev = {
110	NVRAM_MINOR,
111	"nvram",
112	&nvram_fops
113};
114
115int __init nvram_init(void)
116{
117	struct device_node *nvram;
118	unsigned int *nbytes_p, proplen;
119	if ((nvram = find_type_devices("nvram")) != NULL) {
120		nbytes_p = (unsigned int *)get_property(nvram, "#bytes", &proplen);
121		if (nbytes_p && proplen == sizeof(unsigned int)) {
122			rtas_nvram_size = *nbytes_p;
123		}
124	}
125	nvram_fetch = rtas_token("nvram-fetch");
126	nvram_store = rtas_token("nvram-store");
127	printk(KERN_INFO "PPC64 nvram contains %d bytes\n", rtas_nvram_size);
128
129	misc_register(&nvram_dev);
130	return 0;
131}
132
133void __exit nvram_cleanup(void)
134{
135        misc_deregister( &nvram_dev );
136}
137
138module_init(nvram_init);
139module_exit(nvram_cleanup);
140MODULE_LICENSE("GPL");
141