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