1 /*
2 * Generic /dev/nvram driver for architectures providing some
3 * "generic" hooks, that is :
4 *
5 * nvram_read_byte, nvram_write_byte, nvram_sync, nvram_get_size
6 *
7 * Note that an additional hook is supported for PowerMac only
8 * for getting the nvram "partition" informations
9 *
10 */
11
12 #define NVRAM_VERSION "1.1"
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/init.h>
22 #include <linux/mutex.h>
23 #include <asm/uaccess.h>
24 #include <asm/nvram.h>
25 #ifdef CONFIG_PPC_PMAC
26 #include <asm/machdep.h>
27 #endif
28
29 #define NVRAM_SIZE 8192
30
31 static DEFINE_MUTEX(nvram_mutex);
32 static ssize_t nvram_len;
33
nvram_llseek(struct file * file,loff_t offset,int origin)34 static loff_t nvram_llseek(struct file *file, loff_t offset, int origin)
35 {
36 switch (origin) {
37 case 0:
38 break;
39 case 1:
40 offset += file->f_pos;
41 break;
42 case 2:
43 offset += nvram_len;
44 break;
45 default:
46 offset = -1;
47 }
48 if (offset < 0)
49 return -EINVAL;
50
51 file->f_pos = offset;
52
53 return file->f_pos;
54 }
55
read_nvram(struct file * file,char __user * buf,size_t count,loff_t * ppos)56 static ssize_t read_nvram(struct file *file, char __user *buf,
57 size_t count, loff_t *ppos)
58 {
59 unsigned int i;
60 char __user *p = buf;
61
62 if (!access_ok(VERIFY_WRITE, buf, count))
63 return -EFAULT;
64 if (*ppos >= nvram_len)
65 return 0;
66 for (i = *ppos; count > 0 && i < nvram_len; ++i, ++p, --count)
67 if (__put_user(nvram_read_byte(i), p))
68 return -EFAULT;
69 *ppos = i;
70 return p - buf;
71 }
72
write_nvram(struct file * file,const char __user * buf,size_t count,loff_t * ppos)73 static ssize_t write_nvram(struct file *file, const char __user *buf,
74 size_t count, loff_t *ppos)
75 {
76 unsigned int i;
77 const char __user *p = buf;
78 char c;
79
80 if (!access_ok(VERIFY_READ, buf, count))
81 return -EFAULT;
82 if (*ppos >= nvram_len)
83 return 0;
84 for (i = *ppos; count > 0 && i < nvram_len; ++i, ++p, --count) {
85 if (__get_user(c, p))
86 return -EFAULT;
87 nvram_write_byte(c, i);
88 }
89 *ppos = i;
90 return p - buf;
91 }
92
nvram_ioctl(struct file * file,unsigned int cmd,unsigned long arg)93 static int nvram_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
94 {
95 switch(cmd) {
96 #ifdef CONFIG_PPC_PMAC
97 case OBSOLETE_PMAC_NVRAM_GET_OFFSET:
98 printk(KERN_WARNING "nvram: Using obsolete PMAC_NVRAM_GET_OFFSET ioctl\n");
99 case IOC_NVRAM_GET_OFFSET: {
100 int part, offset;
101
102 if (!machine_is(powermac))
103 return -EINVAL;
104 if (copy_from_user(&part, (void __user*)arg, sizeof(part)) != 0)
105 return -EFAULT;
106 if (part < pmac_nvram_OF || part > pmac_nvram_NR)
107 return -EINVAL;
108 offset = pmac_get_partition(part);
109 if (copy_to_user((void __user*)arg, &offset, sizeof(offset)) != 0)
110 return -EFAULT;
111 break;
112 }
113 #endif /* CONFIG_PPC_PMAC */
114 case IOC_NVRAM_SYNC:
115 nvram_sync();
116 break;
117 default:
118 return -EINVAL;
119 }
120
121 return 0;
122 }
123
nvram_unlocked_ioctl(struct file * file,unsigned int cmd,unsigned long arg)124 static long nvram_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
125 {
126 int ret;
127
128 mutex_lock(&nvram_mutex);
129 ret = nvram_ioctl(file, cmd, arg);
130 mutex_unlock(&nvram_mutex);
131
132 return ret;
133 }
134
135 const struct file_operations nvram_fops = {
136 .owner = THIS_MODULE,
137 .llseek = nvram_llseek,
138 .read = read_nvram,
139 .write = write_nvram,
140 .unlocked_ioctl = nvram_unlocked_ioctl,
141 };
142
143 static struct miscdevice nvram_dev = {
144 NVRAM_MINOR,
145 "nvram",
146 &nvram_fops
147 };
148
nvram_init(void)149 int __init nvram_init(void)
150 {
151 int ret = 0;
152
153 printk(KERN_INFO "Generic non-volatile memory driver v%s\n",
154 NVRAM_VERSION);
155 ret = misc_register(&nvram_dev);
156 if (ret != 0)
157 goto out;
158
159 nvram_len = nvram_get_size();
160 if (nvram_len < 0)
161 nvram_len = NVRAM_SIZE;
162
163 out:
164 return ret;
165 }
166
nvram_cleanup(void)167 void __exit nvram_cleanup(void)
168 {
169 misc_deregister( &nvram_dev );
170 }
171
172 module_init(nvram_init);
173 module_exit(nvram_cleanup);
174 MODULE_LICENSE("GPL");
175