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
 32static DEFINE_MUTEX(nvram_mutex);
 33static ssize_t nvram_len;
 34
 35static 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
 41static 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
 58static 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
 78static 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
109static 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
120const 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
128static struct miscdevice nvram_dev = {
129	NVRAM_MINOR,
130	"nvram",
131	&nvram_fops
132};
133
134int __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
148out:
149	return ret;
150}
151
152void __exit nvram_cleanup(void)
153{
154        misc_deregister( &nvram_dev );
155}
156
157module_init(nvram_init);
158module_exit(nvram_cleanup);
159MODULE_LICENSE("GPL");