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
 31static DEFINE_MUTEX(nvram_mutex);
 32static ssize_t nvram_len;
 33
 34static 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
 56static 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
 73static 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
 93static 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
124static 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
135const 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
143static struct miscdevice nvram_dev = {
144	NVRAM_MINOR,
145	"nvram",
146	&nvram_fops
147};
148
149int __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
163out:
164	return ret;
165}
166
167void __exit nvram_cleanup(void)
168{
169        misc_deregister( &nvram_dev );
170}
171
172module_init(nvram_init);
173module_exit(nvram_cleanup);
174MODULE_LICENSE("GPL");