Cross-Referenced Linux and Device Driver Code

http://www.cs.fsu.edu/~baker/devices/lxr/http/source/linux/drivers/char/nvram.c

Linux kernel & device driver programming

Cross-ReferencedLinux and Device Driver Code

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Version: [ 2.6.11.8 ] [ 2.6.25 ] [ 2.6.25.8 ] [ 2.6.31.13 ] Architecture: [ i386 ]

   /*    * CMOS/NV-RAM driver for Linux    *    * Copyright (C) 1997 Roman Hodek <[e-mail]>    * idea by and with help from Richard Jelinek <[e-mail]>    * Portions copyright (c) 2001,2002 Sun Microsystems ([e-mail])    *    * This driver allows you to access the contents of the non-volatile memory in    * the mc146818rtc.h real-time clock. This chip is built into all PCs and into   * many Atari machines. In the former it's called "CMOS-RAM", in the latter   * "NVRAM" (NV stands for non-volatile).   *   * The data are supplied as a (seekable) character device, /dev/nvram. The   * size of this file is dependent on the controller.  The usual size is 114,   * the number of freely available bytes in the memory (i.e., not used by the   * RTC itself).   *   * Checksums over the NVRAM contents are managed by this driver. In case of a   * bad checksum, reads and writes return -EIO. The checksum can be initialized   * to a sane state either by ioctl(NVRAM_INIT) (clear whole NVRAM) or   * ioctl(NVRAM_SETCKS) (doesn't change contents, just makes checksum valid   * again; use with care!)   *   * This file also provides some functions for other parts of the kernel that   * want to access the NVRAM: nvram_{read,write,check_checksum,set_checksum}.   * Obviously this can be used only if this driver is always configured into   * the kernel and is not a module. Since the functions are used by some Atari   * drivers, this is the case on the Atari.   *   *   *      1.1     Cesar Barros: SMP locking fixes   *              added changelog   *      1.2     Erik Gilling: Cobalt Networks support   *              Tim Hockin: general cleanup, Cobalt support   *      1.3     Wim Van Sebroeck: convert PRINT_PROC to seq_file   */    #define NVRAM_VERSION   "1.3"    #include <linux/module.h>  #include <linux/smp_lock.h>  #include <linux/nvram.h>    #define PC              1  #define ATARI           2    /* select machine configuration */  #if defined(CONFIG_ATARI)  #  define MACH ATARI  #elif defined(__i386__) || defined(__x86_64__) || defined(__arm__)  /* and ?? */  #  define MACH PC  #else  #  error Cannot build nvram driver for this machine configuration.  #endif    #if MACH == PC    /* RTC in a PC */  #define CHECK_DRIVER_INIT()     1    /* On PCs, the checksum is built only over bytes 2..31 */  #define PC_CKS_RANGE_START      2  #define PC_CKS_RANGE_END        31  #define PC_CKS_LOC              32  #define NVRAM_BYTES             (128-NVRAM_FIRST_BYTE)    #define mach_check_checksum     pc_check_checksum  #define mach_set_checksum       pc_set_checksum  #define mach_proc_infos         pc_proc_infos    #endif    #if MACH == ATARI    /* Special parameters for RTC in Atari machines */  #include <asm/atarihw.h>  #include <asm/atariints.h>  #define RTC_PORT(x)             (TT_RTC_BAS + 2*(x))  #define CHECK_DRIVER_INIT()     (MACH_IS_ATARI && ATARIHW_PRESENT(TT_CLK))    #define NVRAM_BYTES             50    /* On Ataris, the checksum is over all bytes except the checksum bytes   * themselves; these are at the very end */  #define ATARI_CKS_RANGE_START   0  #define ATARI_CKS_RANGE_END     47  #define ATARI_CKS_LOC           48    #define mach_check_checksum     atari_check_checksum  #define mach_set_checksum       atari_set_checksum  #define mach_proc_infos         atari_proc_infos    #endif    /* Note that *all* calls to CMOS_READ and CMOS_WRITE must be done with   * rtc_lock held. Due to the index-port/data-port design of the RTC, we   * don't want two different things trying to get to it at once. (e.g. the   * periodic 11 min sync from time.c vs. this driver.)   */  #include <linux/types.h> #include <linux/errno.h> #include <linux/miscdevice.h> #include <linux/slab.h> #include <linux/ioport.h> #include <linux/fcntl.h> #include <linux/mc146818rtc.h> #include <linux/init.h> #include <linux/proc_fs.h> #include <linux/seq_file.h> #include <linux/spinlock.h> #include <linux/io.h> #include <linux/uaccess.h>  #include <asm/system.h>  static DEFINE_SPINLOCK(nvram_state_lock); static int nvram_open_cnt;      /* #times opened */ static int nvram_open_mode;     /* special open modes */ #define NVRAM_WRITE             1 /* opened for writing (exclusive) */ #define NVRAM_EXCL              2 /* opened with O_EXCL */  static int mach_check_checksum(void); static void mach_set_checksum(void);  #ifdef CONFIG_PROC_FS static void mach_proc_infos(unsigned char *contents, struct seq_file *seq,                                                                 void *offset); #endif  /*  * These functions are provided to be called internally or by other parts of  * the kernel. It's up to the caller to ensure correct checksum before reading  * or after writing (needs to be done only once).  *  * It is worth noting that these functions all access bytes of general  * purpose memory in the NVRAM - that is to say, they all add the  * NVRAM_FIRST_BYTE offset.  Pass them offsets into NVRAM as if you did not  * know about the RTC cruft.  */  unsigned char __nvram_read_byte(int i) {         return CMOS_READ(NVRAM_FIRST_BYTE + i); } EXPORT_SYMBOL(__nvram_read_byte);  unsigned char nvram_read_byte(int i) {         unsigned long flags;         unsigned char c;          spin_lock_irqsave(&rtc_lock, flags);         c = __nvram_read_byte(i);         spin_unlock_irqrestore(&rtc_lock, flags);         return c; } EXPORT_SYMBOL(nvram_read_byte);  /* This races nicely with trying to read with checksum checking (nvram_read) */ void __nvram_write_byte(unsigned char c, int i) {         CMOS_WRITE(c, NVRAM_FIRST_BYTE + i); } EXPORT_SYMBOL(__nvram_write_byte);  void nvram_write_byte(unsigned char c, int i) {         unsigned long flags;          spin_lock_irqsave(&rtc_lock, flags);         __nvram_write_byte(c, i);         spin_unlock_irqrestore(&rtc_lock, flags); } EXPORT_SYMBOL(nvram_write_byte);  int __nvram_check_checksum(void) {         return mach_check_checksum(); } EXPORT_SYMBOL(__nvram_check_checksum);  int nvram_check_checksum(void) {         unsigned long flags;         int rv;          spin_lock_irqsave(&rtc_lock, flags);         rv = __nvram_check_checksum();         spin_unlock_irqrestore(&rtc_lock, flags);         return rv; } EXPORT_SYMBOL(nvram_check_checksum);  static void __nvram_set_checksum(void) {         mach_set_checksum(); }  #if 0 void nvram_set_checksum(void) {         unsigned long flags;          spin_lock_irqsave(&rtc_lock, flags);         __nvram_set_checksum();         spin_unlock_irqrestore(&rtc_lock, flags); } #endif  /*  0  */  /*  * The are the file operation function for user access to /dev/nvram  */  static loff_t nvram_llseek(struct file *file, loff_t offset, int origin) {         lock_kernel();         switch (origin) {         case 0:                 /* nothing to do */                 break;         case 1:                 offset += file->f_pos;                 break;         case 2:                 offset += NVRAM_BYTES;                 break;         }         unlock_kernel();         return (offset >= 0) ? (file->f_pos = offset) : -EINVAL; }  static ssize_t nvram_read(struct file *file, char __user *buf,                                                 size_t count, loff_t *ppos) {         unsigned char contents[NVRAM_BYTES];         unsigned i = *ppos;         unsigned char *tmp;          spin_lock_irq(&rtc_lock);          if (!__nvram_check_checksum())                 goto checksum_err;          for (tmp = contents; count-- > 0 && i < NVRAM_BYTES; ++i, ++tmp)                 *tmp = __nvram_read_byte(i);          spin_unlock_irq(&rtc_lock);          if (copy_to_user(buf, contents, tmp - contents))                 return -EFAULT;          *ppos = i;          return tmp - contents;  checksum_err:         spin_unlock_irq(&rtc_lock);         return -EIO; }  static ssize_t nvram_write(struct file *file, const char __user *buf,                                                 size_t count, loff_t *ppos) {         unsigned char contents[NVRAM_BYTES];         unsigned i = *ppos;         unsigned char *tmp;         int len;          len = (NVRAM_BYTES - i) < count ? (NVRAM_BYTES - i) : count;         if (copy_from_user(contents, buf, len))                 return -EFAULT;          spin_lock_irq(&rtc_lock);          if (!__nvram_check_checksum())                 goto checksum_err;          for (tmp = contents; count-- > 0 && i < NVRAM_BYTES; ++i, ++tmp)                 __nvram_write_byte(*tmp, i);          __nvram_set_checksum();          spin_unlock_irq(&rtc_lock);          *ppos = i;          return tmp - contents;  checksum_err:         spin_unlock_irq(&rtc_lock);         return -EIO; }  static int nvram_ioctl(struct inode *inode, struct file *file,                                         unsigned int cmd, unsigned long arg) {         int i;          switch (cmd) {          case NVRAM_INIT:                 /* initialize NVRAM contents and checksum */                 if (!capable(CAP_SYS_ADMIN))                         return -EACCES;                  spin_lock_irq(&rtc_lock);                  for (i = 0; i < NVRAM_BYTES; ++i)                         __nvram_write_byte(0, i);                 __nvram_set_checksum();                  spin_unlock_irq(&rtc_lock);                 return 0;          case NVRAM_SETCKS:                 /* just set checksum, contents unchanged (maybe useful after                  * checksum garbaged somehow...) */                 if (!capable(CAP_SYS_ADMIN))                         return -EACCES;                  spin_lock_irq(&rtc_lock);                 __nvram_set_checksum();                 spin_unlock_irq(&rtc_lock);                 return 0;          default:                 return -ENOTTY;         } }  static int nvram_open(struct inode *inode, struct file *file) {         lock_kernel();         spin_lock(&nvram_state_lock);          if ((nvram_open_cnt && (file->f_flags & O_EXCL)) ||             (nvram_open_mode & NVRAM_EXCL) ||             ((file->f_mode & FMODE_WRITE) && (nvram_open_mode & NVRAM_WRITE))) {                 spin_unlock(&nvram_state_lock);                 unlock_kernel();                 return -EBUSY;         }          if (file->f_flags & O_EXCL)                 nvram_open_mode |= NVRAM_EXCL;         if (file->f_mode & FMODE_WRITE)                 nvram_open_mode |= NVRAM_WRITE;         nvram_open_cnt++;          spin_unlock(&nvram_state_lock);         unlock_kernel();          return 0; }  static int nvram_release(struct inode *inode, struct file *file) {         spin_lock(&nvram_state_lock);          nvram_open_cnt--;          /* if only one instance is open, clear the EXCL bit */         if (nvram_open_mode & NVRAM_EXCL)                 nvram_open_mode &= ~NVRAM_EXCL;         if (file->f_mode & FMODE_WRITE)                 nvram_open_mode &= ~NVRAM_WRITE;          spin_unlock(&nvram_state_lock);          return 0; }  #ifndef CONFIG_PROC_FS static int nvram_add_proc_fs(void) {         return 0; }  #else  static int nvram_proc_read(struct seq_file *seq, void *offset) {         unsigned char contents[NVRAM_BYTES];         int i = 0;          spin_lock_irq(&rtc_lock);         for (i = 0; i < NVRAM_BYTES; ++i)                 contents[i] = __nvram_read_byte(i);         spin_unlock_irq(&rtc_lock);          mach_proc_infos(contents, seq, offset);          return 0; }  static int nvram_proc_open(struct inode *inode, struct file *file) {         return single_open(file, nvram_proc_read, NULL); }  static const struct file_operations nvram_proc_fops = {         .owner          = THIS_MODULE,         .open           = nvram_proc_open,         .read           = seq_read,         .llseek         = seq_lseek,         .release        = single_release, };  static int nvram_add_proc_fs(void) {         if (!proc_create("driver/nvram", 0, NULL, &nvram_proc_fops))                 return -ENOMEM;         return 0; }  #endif /* CONFIG_PROC_FS */  static const struct file_operations nvram_fops = {         .owner          = THIS_MODULE,         .llseek         = nvram_llseek,         .read           = nvram_read,         .write          = nvram_write,         .ioctl          = nvram_ioctl,         .open           = nvram_open,         .release        = nvram_release, };  static struct miscdevice nvram_dev = {         NVRAM_MINOR,         "nvram",         &nvram_fops };  static int __init nvram_init(void) {         int ret;          /* First test whether the driver should init at all */         if (!CHECK_DRIVER_INIT())                 return -ENODEV;          ret = misc_register(&nvram_dev);         if (ret) {                 printk(KERN_ERR "nvram: can't misc_register on minor=%d\n",                     NVRAM_MINOR);                 goto out;         }         ret = nvram_add_proc_fs();         if (ret) {                 printk(KERN_ERR "nvram: can't create /proc/driver/nvram\n");                 goto outmisc;         }         ret = 0;         printk(KERN_INFO "Non-volatile memory driver v" NVRAM_VERSION "\n"); out:         return ret; outmisc:         misc_deregister(&nvram_dev);         goto out; }  static void __exit nvram_cleanup_module(void) {         remove_proc_entry("driver/nvram", NULL);         misc_deregister(&nvram_dev); }  module_init(nvram_init); module_exit(nvram_cleanup_module);  /*  * Machine specific functions  */  #if MACH == PC  static int pc_check_checksum(void) {         int i;         unsigned short sum = 0;         unsigned short expect;          for (i = PC_CKS_RANGE_START; i <= PC_CKS_RANGE_END; ++i)                 sum += __nvram_read_byte(i);         expect = __nvram_read_byte(PC_CKS_LOC)<<8 |             __nvram_read_byte(PC_CKS_LOC+1);         return (sum & 0xffff) == expect; }  static void pc_set_checksum(void) {         int i;         unsigned short sum = 0;          for (i = PC_CKS_RANGE_START; i <= PC_CKS_RANGE_END; ++i)                 sum += __nvram_read_byte(i);         __nvram_write_byte(sum >> 8, PC_CKS_LOC);         __nvram_write_byte(sum & 0xff, PC_CKS_LOC + 1); }  #ifdef CONFIG_PROC_FS  static char *floppy_types[] = {         "none", "5.25'' 360k", "5.25'' 1.2M", "3.5'' 720k", "3.5'' 1.44M",         "3.5'' 2.88M", "3.5'' 2.88M" };  static char *gfx_types[] = {         "EGA, VGA, ... (with BIOS)",         "CGA (40 cols)",         "CGA (80 cols)",         "monochrome", };  static void pc_proc_infos(unsigned char *nvram, struct seq_file *seq,                                                                 void *offset) {         int checksum;         int type;          spin_lock_irq(&rtc_lock);         checksum = __nvram_check_checksum();         spin_unlock_irq(&rtc_lock);          seq_printf(seq, "Checksum status: %svalid\n", checksum ? "" : "not ");          seq_printf(seq, "# floppies     : %d\n",             (nvram[6] & 1) ? (nvram[6] >> 6) + 1 : 0);         seq_printf(seq, "Floppy 0 type  : ");         type = nvram[2] >> 4;         if (type < ARRAY_SIZE(floppy_types))                 seq_printf(seq, "%s\n", floppy_types[type]);         else                 seq_printf(seq, "%d (unknown)\n", type);         seq_printf(seq, "Floppy 1 type  : ");         type = nvram[2] & 0x0f;         if (type < ARRAY_SIZE(floppy_types))                 seq_printf(seq, "%s\n", floppy_types[type]);         else                 seq_printf(seq, "%d (unknown)\n", type);          seq_printf(seq, "HD 0 type      : ");         type = nvram[4] >> 4;         if (type)                 seq_printf(seq, "%02x\n", type == 0x0f ? nvram[11] : type);         else                 seq_printf(seq, "none\n");          seq_printf(seq, "HD 1 type      : ");         type = nvram[4] & 0x0f;         if (type)                 seq_printf(seq, "%02x\n", type == 0x0f ? nvram[12] : type);         else                 seq_printf(seq, "none\n");          seq_printf(seq, "HD type 48 data: %d/%d/%d C/H/S, precomp %d, lz %d\n",             nvram[18] | (nvram[19] << 8),             nvram[20], nvram[25],             nvram[21] | (nvram[22] << 8), nvram[23] | (nvram[24] << 8));         seq_printf(seq, "HD type 49 data: %d/%d/%d C/H/S, precomp %d, lz %d\n",             nvram[39] | (nvram[40] << 8),             nvram[41], nvram[46],             nvram[42] | (nvram[43] << 8), nvram[44] | (nvram[45] << 8));          seq_printf(seq, "DOS base memory: %d kB\n", nvram[7] | (nvram[8] << 8));         seq_printf(seq, "Extended memory: %d kB (configured), %d kB (tested)\n",             nvram[9] | (nvram[10] << 8), nvram[34] | (nvram[35] << 8));          seq_printf(seq, "Gfx adapter    : %s\n",             gfx_types[(nvram[6] >> 4) & 3]);          seq_printf(seq, "FPU            : %sinstalled\n",             (nvram[6] & 2) ? "" : "not ");          return; } #endif  #endif /* MACH == PC */  #if MACH == ATARI  static int atari_check_checksum(void) {         int i;         unsigned char sum = 0;          for (i = ATARI_CKS_RANGE_START; i <= ATARI_CKS_RANGE_END; ++i)                 sum += __nvram_read_byte(i);         return (__nvram_read_byte(ATARI_CKS_LOC) == (~sum & 0xff)) &&             (__nvram_read_byte(ATARI_CKS_LOC + 1) == (sum & 0xff)); }  static void atari_set_checksum(void) {         int i;         unsigned char sum = 0;          for (i = ATARI_CKS_RANGE_START; i <= ATARI_CKS_RANGE_END; ++i)                 sum += __nvram_read_byte(i);         __nvram_write_byte(~sum, ATARI_CKS_LOC);         __nvram_write_byte(sum, ATARI_CKS_LOC + 1); }  #ifdef CONFIG_PROC_FS  static struct {         unsigned char val;         char *name; } boot_prefs[] = {         { 0x80, "TOS" },         { 0x40, "ASV" },         { 0x20, "NetBSD (?)" },         { 0x10, "Linux" },         { 0x00, "unspecified" } };  static char *languages[] = {         "English (US)",         "German",         "French",         "English (UK)",         "Spanish",         "Italian",         "6 (undefined)",         "Swiss (French)",         "Swiss (German)" };  static char *dateformat[] = {         "MM%cDD%cYY",         "DD%cMM%cYY",         "YY%cMM%cDD",         "YY%cDD%cMM",         "4 (undefined)",         "5 (undefined)",         "6 (undefined)",         "7 (undefined)" };  static char *colors[] = {         "2", "4", "16", "256", "65536", "??", "??", "??" };  static void atari_proc_infos(unsigned char *nvram, struct seq_file *seq,                                                                 void *offset) {         int checksum = nvram_check_checksum();         int i;         unsigned vmode;          seq_printf(seq, "Checksum status  : %svalid\n", checksum ? "" : "not ");          seq_printf(seq, "Boot preference  : ");         for (i = ARRAY_SIZE(boot_prefs) - 1; i >= 0; --i) {                 if (nvram[1] == boot_prefs[i].val) {                         seq_printf(seq, "%s\n", boot_prefs[i].name);                         break;                 }         }         if (i < 0)                 seq_printf(seq, "0x%02x (undefined)\n", nvram[1]);          seq_printf(seq, "SCSI arbitration : %s\n",             (nvram[16] & 0x80) ? "on" : "off");         seq_printf(seq, "SCSI host ID     : ");         if (nvram[16] & 0x80)                 seq_printf(seq, "%d\n", nvram[16] & 7);         else                 seq_printf(seq, "n/a\n");          /* the following entries are defined only for the Falcon */         if ((atari_mch_cookie >> 16) != ATARI_MCH_FALCON)                 return;          seq_printf(seq, "OS language      : ");         if (nvram[6] < ARRAY_SIZE(languages))                 seq_printf(seq, "%s\n", languages[nvram[6]]);         else                 seq_printf(seq, "%u (undefined)\n", nvram[6]);         seq_printf(seq, "Keyboard language: ");         if (nvram[7] < ARRAY_SIZE(languages))                 seq_printf(seq, "%s\n", languages[nvram[7]]);         else                 seq_printf(seq, "%u (undefined)\n", nvram[7]);         seq_printf(seq, "Date format      : ");         seq_printf(seq, dateformat[nvram[8] & 7],             nvram[9] ? nvram[9] : '/', nvram[9] ? nvram[9] : '/');         seq_printf(seq, ", %dh clock\n", nvram[8] & 16 ? 24 : 12);         seq_printf(seq, "Boot delay       : ");         if (nvram[10] == 0)                 seq_printf(seq, "default");         else                 seq_printf(seq, "%ds%s\n", nvram[10],                     nvram[10] < 8 ? ", no memory test" : "");          vmode = (nvram[14] << 8) || nvram[15];         seq_printf(seq,             "Video mode       : %s colors, %d columns, %s %s monitor\n",             colors[vmode & 7],             vmode & 8 ? 80 : 40,             vmode & 16 ? "VGA" : "TV", vmode & 32 ? "PAL" : "NTSC");         seq_printf(seq, "                   %soverscan, compat. mode %s%s\n",             vmode & 64 ? "" : "no ",             vmode & 128 ? "on" : "off",             vmode & 256 ?             (vmode & 16 ? ", line doubling" : ", half screen") : "");          return; } #endif  #endif /* MACH == ATARI */  MODULE_LICENSE("GPL"); MODULE_ALIAS_MISCDEV(NVRAM_MINOR); 

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