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;
  41         int done;
  42         unsigned long flags;
  43         char *p = buf;
  44
  45
  46         if (nvram_size == 0 || nvram_fetch == RTAS_UNKNOWN_SERVICE)
  47                 return -ENODEV;
  48
  49         if (*index >= nvram_size)
  50                 return 0;
  51
  52         i = *index;
  53         if (i + count > nvram_size)
  54                 count = nvram_size - i;
  55
  56         spin_lock_irqsave(&nvram_lock, flags);
  57
  58         for (; count != 0; count -= len) {
  59                 len = count;
  60                 if (len > NVRW_CNT)
  61                         len = NVRW_CNT;
  62
  63                 if ((rtas_call(nvram_fetch, 3, 2, &done, i, __pa(nvram_buf),
  64                                len) != 0) || len != done) {
  65                         spin_unlock_irqrestore(&nvram_lock, flags);
  66                         return -EIO;
  67                 }
  68
  69                 memcpy(p, nvram_buf, len);
  70
  71                 p += len;
  72                 i += len;
  73         }
  74
  75         spin_unlock_irqrestore(&nvram_lock, flags);
  76
  77         *index = i;
  78         return p - buf;
  79 }
  80
  81 static ssize_t pSeries_nvram_write(char *buf, size_t count, loff_t *index)
  82 {
  83         unsigned int i;
  84         unsigned long len;
  85         int done;
  86         unsigned long flags;
  87         const char *p = buf;
  88
  89         if (nvram_size == 0 || nvram_store == RTAS_UNKNOWN_SERVICE)
  90                 return -ENODEV;
  91
  92         if (*index >= nvram_size)
  93                 return 0;
  94
  95         i = *index;
  96         if (i + count > nvram_size)
  97                 count = nvram_size - i;
  98
  99         spin_lock_irqsave(&nvram_lock, flags);
 100
 101         for (; count != 0; count -= len) {
 102                 len = count;
 103                 if (len > NVRW_CNT)
 104                         len = NVRW_CNT;
 105
 106                 memcpy(nvram_buf, p, len);
 107
 108                 if ((rtas_call(nvram_store, 3, 2, &done, i, __pa(nvram_buf),
 109                                len) != 0) || len != done) {
 110                         spin_unlock_irqrestore(&nvram_lock, flags);
 111                         return -EIO;
 112                 }
 113
 114                 p += len;
 115                 i += len;
 116         }
 117         spin_unlock_irqrestore(&nvram_lock, flags);
 118
 119         *index = i;
 120         return p - buf;
 121 }
 122
 123 static ssize_t pSeries_nvram_get_size(void)
 124 {
 125         return nvram_size ? nvram_size : -ENODEV;
 126 }
 127
 128 int __init pSeries_nvram_init(void)
 129 {
 130         struct device_node *nvram;
 131         unsigned int *nbytes_p, proplen;
 132
 133         nvram = of_find_node_by_type(NULL, "nvram");
 134         if (nvram == NULL)
 135                 return -ENODEV;
 136
 137         nbytes_p = (unsigned int *)get_property(nvram, "#bytes", &proplen);
 138         if (nbytes_p == NULL || proplen != sizeof(unsigned int))
 139                 return -EIO;
 140
 141         nvram_size = *nbytes_p;
 142
 143         nvram_fetch = rtas_token("nvram-fetch");
 144         nvram_store = rtas_token("nvram-store");
 145         printk(KERN_INFO "PPC64 nvram contains %d bytes\n", nvram_size);
 146         of_node_put(nvram);
 147
 148         ppc_md.nvram_read       = pSeries_nvram_read;
 149         ppc_md.nvram_write      = pSeries_nvram_write;
 150         ppc_md.nvram_size       = pSeries_nvram_get_size;
 151
 152         return 0;
 153 }