/drivers/char/generic_nvram.c
C | 170 lines | 134 code | 26 blank | 10 comment | 22 complexity | bf20935473dc96c8639a0c1a351c3ea3 MD5 | raw file
Possible License(s): GPL-2.0, LGPL-2.0, AGPL-1.0
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");