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