Merge branch 'bkl-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git...
[sfrench/cifs-2.6.git] / drivers / char / generic_nvram.c
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/smp_lock.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 ssize_t nvram_len;
32
33 static loff_t nvram_llseek(struct file *file, loff_t offset, int origin)
34 {
35         lock_kernel();
36         switch (origin) {
37         case 1:
38                 offset += file->f_pos;
39                 break;
40         case 2:
41                 offset += nvram_len;
42                 break;
43         }
44         if (offset < 0) {
45                 unlock_kernel();
46                 return -EINVAL;
47         }
48         file->f_pos = offset;
49         unlock_kernel();
50         return file->f_pos;
51 }
52
53 static ssize_t read_nvram(struct file *file, char __user *buf,
54                           size_t count, loff_t *ppos)
55 {
56         unsigned int i;
57         char __user *p = buf;
58
59         if (!access_ok(VERIFY_WRITE, buf, count))
60                 return -EFAULT;
61         if (*ppos >= nvram_len)
62                 return 0;
63         for (i = *ppos; count > 0 && i < nvram_len; ++i, ++p, --count)
64                 if (__put_user(nvram_read_byte(i), p))
65                         return -EFAULT;
66         *ppos = i;
67         return p - buf;
68 }
69
70 static ssize_t write_nvram(struct file *file, const char __user *buf,
71                            size_t count, loff_t *ppos)
72 {
73         unsigned int i;
74         const char __user *p = buf;
75         char c;
76
77         if (!access_ok(VERIFY_READ, buf, count))
78                 return -EFAULT;
79         if (*ppos >= nvram_len)
80                 return 0;
81         for (i = *ppos; count > 0 && i < nvram_len; ++i, ++p, --count) {
82                 if (__get_user(c, p))
83                         return -EFAULT;
84                 nvram_write_byte(c, i);
85         }
86         *ppos = i;
87         return p - buf;
88 }
89
90 static int nvram_ioctl(struct inode *inode, struct file *file,
91         unsigned int cmd, unsigned long arg)
92 {
93         switch(cmd) {
94 #ifdef CONFIG_PPC_PMAC
95         case OBSOLETE_PMAC_NVRAM_GET_OFFSET:
96                 printk(KERN_WARNING "nvram: Using obsolete PMAC_NVRAM_GET_OFFSET ioctl\n");
97         case IOC_NVRAM_GET_OFFSET: {
98                 int part, offset;
99
100                 if (!machine_is(powermac))
101                         return -EINVAL;
102                 if (copy_from_user(&part, (void __user*)arg, sizeof(part)) != 0)
103                         return -EFAULT;
104                 if (part < pmac_nvram_OF || part > pmac_nvram_NR)
105                         return -EINVAL;
106                 offset = pmac_get_partition(part);
107                 if (copy_to_user((void __user*)arg, &offset, sizeof(offset)) != 0)
108                         return -EFAULT;
109                 break;
110         }
111 #endif /* CONFIG_PPC_PMAC */
112         case IOC_NVRAM_SYNC:
113                 nvram_sync();
114                 break;
115         default:
116                 return -EINVAL;
117         }
118
119         return 0;
120 }
121
122 const struct file_operations nvram_fops = {
123         .owner          = THIS_MODULE,
124         .llseek         = nvram_llseek,
125         .read           = read_nvram,
126         .write          = write_nvram,
127         .ioctl          = nvram_ioctl,
128 };
129
130 static struct miscdevice nvram_dev = {
131         NVRAM_MINOR,
132         "nvram",
133         &nvram_fops
134 };
135
136 int __init nvram_init(void)
137 {
138         int ret = 0;
139
140         printk(KERN_INFO "Generic non-volatile memory driver v%s\n",
141                 NVRAM_VERSION);
142         ret = misc_register(&nvram_dev);
143         if (ret != 0)
144                 goto out;
145
146         nvram_len = nvram_get_size();
147         if (nvram_len < 0)
148                 nvram_len = NVRAM_SIZE;
149
150 out:
151         return ret;
152 }
153
154 void __exit nvram_cleanup(void)
155 {
156         misc_deregister( &nvram_dev );
157 }
158
159 module_init(nvram_init);
160 module_exit(nvram_cleanup);
161 MODULE_LICENSE("GPL");