arch/ppc64/kernel/pSeries_nvram.c

   1 /*
   2  *  c 2001 PPC 64 Team, IBM Corp
   3  *
   4  *      This program is free software; you can redistribute it and/or
   5  *      modify it under the terms of the GNU General Public License
   6  *      as published by the Free Software Foundation; either version
   7  *      2 of the License, or (at your option) any later version.
   8  *
   9  * /dev/nvram driver for PPC64
  10  *
  11  * This perhaps should live in drivers/char
  12  */
  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/nvram.h>
  22 #include <linux/init.h>
  23 #include <linux/slab.h>
  24 #include <linux/spinlock.h>
  25 #include <asm/uaccess.h>
  26 #include <asm/nvram.h>
  27 #include <asm/rtas.h>
  28 #include <asm/prom.h>
  29 #include <asm/machdep.h>
  30
  31 static unsigned int nvram_size;
  32 static int nvram_fetch, nvram_store;
  33 static char nvram_buf[NVRW_CNT];        /* assume this is in the first 4GB */
  34 static spinlock_t nvram_lock = SPIN_LOCK_UNLOCKED;
  35
  36
  37 static ssize_t pSeries_nvram_read(char *buf, size_t count, loff_t *index)
  38 {
  39         unsigned int i;
  40         unsigned long len, done;
  41         unsigned long flags;
  42         char *p = buf;
  43
  44
  45         if (nvram_size == 0 || nvram_fetch == RTAS_UNKNOWN_SERVICE)
  46                 return -ENODEV;
  47
  48         if (*index >= nvram_size)
  49                 return 0;
  50
  51         i = *index;
  52         if (i + count > nvram_size)
  53                 count = nvram_size - i;
  54
  55         spin_lock_irqsave(&nvram_lock, flags);
  56
  57         for (; count != 0; count -= len) {
  58                 len = count;
  59                 if (len > NVRW_CNT)
  60                         len = NVRW_CNT;
  61
  62                 if ((rtas_call(nvram_fetch, 3, 2, &done, i, __pa(nvram_buf),
  63                                len) != 0) || len != done) {
  64                         spin_unlock_irqrestore(&nvram_lock, flags);
  65                         return -EIO;
  66                 }
  67
  68                 memcpy(p, nvram_buf, len);
  69
  70                 p += len;
  71                 i += len;
  72         }
  73
  74         spin_unlock_irqrestore(&nvram_lock, flags);
  75
  76         *index = i;
  77         return p - buf;
  78 }
  79
  80 static ssize_t pSeries_nvram_write(char *buf, size_t count, loff_t *index)
  81 {
  82         unsigned int i;
  83         unsigned long len, done;
  84         unsigned long flags;
  85         const char *p = buf;
  86
  87         if (nvram_size == 0 || nvram_store == RTAS_UNKNOWN_SERVICE)
  88                 return -ENODEV;
  89
  90         if (*index >= nvram_size)
  91                 return 0;
  92
  93         i = *index;
  94         if (i + count > nvram_size)
  95                 count = nvram_size - i;
  96
  97         spin_lock_irqsave(&nvram_lock, flags);
  98
  99         for (; count != 0; count -= len) {
 100                 len = count;
 101                 if (len > NVRW_CNT)
 102                         len = NVRW_CNT;
 103
 104                 memcpy(nvram_buf, p, len);
 105
 106                 if ((rtas_call(nvram_store, 3, 2, &done, i, __pa(nvram_buf),
 107                                len) != 0) || len != done) {
 108                         spin_unlock_irqrestore(&nvram_lock, flags);
 109                         return -EIO;
 110                 }
 111
 112                 p += len;
 113                 i += len;
 114         }
 115         spin_unlock_irqrestore(&nvram_lock, flags);
 116
 117         *index = i;
 118         return p - buf;
 119 }
 120
 121 static ssize_t pSeries_nvram_get_size(void)
 122 {
 123         return nvram_size ? nvram_size : -ENODEV;
 124 }
 125
 126 int __init pSeries_nvram_init(void)
 127 {
 128         struct device_node *nvram;
 129         unsigned int *nbytes_p, proplen;
 130
 131         nvram = of_find_node_by_type(NULL, "nvram");
 132         if (nvram == NULL)
 133                 return -ENODEV;
 134
 135         nbytes_p = (unsigned int *)get_property(nvram, "#bytes", &proplen);
 136         if (nbytes_p == NULL || proplen != sizeof(unsigned int))
 137                 return -EIO;
 138
 139         nvram_size = *nbytes_p;
 140
 141         nvram_fetch = rtas_token("nvram-fetch");
 142         nvram_store = rtas_token("nvram-store");
 143         printk(KERN_INFO "PPC64 nvram contains %d bytes\n", nvram_size);
 144         of_node_put(nvram);
 145
 146         ppc_md.nvram_read       = pSeries_nvram_read;
 147         ppc_md.nvram_write      = pSeries_nvram_write;
 148         ppc_md.nvram_size       = pSeries_nvram_get_size;
 149
 150         return 0;
 151 }