arch/powerpc/platforms/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
  15 #include <linux/types.h>
  16 #include <linux/errno.h>
  17 #include <linux/init.h>
  18 #include <linux/spinlock.h>
  19 #include <asm/uaccess.h>
  20 #include <asm/nvram.h>
  21 #include <asm/rtas.h>
  22 #include <asm/prom.h>
  23 #include <asm/machdep.h>
  24
  25 static unsigned int nvram_size;
  26 static int nvram_fetch, nvram_store;
  27 static char nvram_buf[NVRW_CNT];        /* assume this is in the first 4GB */
  28 static DEFINE_SPINLOCK(nvram_lock);
  29
  30
  31 static ssize_t pSeries_nvram_read(char *buf, size_t count, loff_t *index)
  32 {
  33         unsigned int i;
  34         unsigned long len;
  35         int done;
  36         unsigned long flags;
  37         char *p = buf;
  38
  39
  40         if (nvram_size == 0 || nvram_fetch == RTAS_UNKNOWN_SERVICE)
  41                 return -ENODEV;
  42
  43         if (*index >= nvram_size)
  44                 return 0;
  45
  46         i = *index;
  47         if (i + count > nvram_size)
  48                 count = nvram_size - i;
  49
  50         spin_lock_irqsave(&nvram_lock, flags);
  51
  52         for (; count != 0; count -= len) {
  53                 len = count;
  54                 if (len > NVRW_CNT)
  55                         len = NVRW_CNT;
  56
  57                 if ((rtas_call(nvram_fetch, 3, 2, &done, i, __pa(nvram_buf),
  58                                len) != 0) || len != done) {
  59                         spin_unlock_irqrestore(&nvram_lock, flags);
  60                         return -EIO;
  61                 }
  62
  63                 memcpy(p, nvram_buf, len);
  64
  65                 p += len;
  66                 i += len;
  67         }
  68
  69         spin_unlock_irqrestore(&nvram_lock, flags);
  70
  71         *index = i;
  72         return p - buf;
  73 }
  74
  75 static ssize_t pSeries_nvram_write(char *buf, size_t count, loff_t *index)
  76 {
  77         unsigned int i;
  78         unsigned long len;
  79         int done;
  80         unsigned long flags;
  81         const char *p = buf;
  82
  83         if (nvram_size == 0 || nvram_store == RTAS_UNKNOWN_SERVICE)
  84                 return -ENODEV;
  85
  86         if (*index >= nvram_size)
  87                 return 0;
  88
  89         i = *index;
  90         if (i + count > nvram_size)
  91                 count = nvram_size - i;
  92
  93         spin_lock_irqsave(&nvram_lock, flags);
  94
  95         for (; count != 0; count -= len) {
  96                 len = count;
  97                 if (len > NVRW_CNT)
  98                         len = NVRW_CNT;
  99
 100                 memcpy(nvram_buf, p, len);
 101
 102                 if ((rtas_call(nvram_store, 3, 2, &done, i, __pa(nvram_buf),
 103                                len) != 0) || len != done) {
 104                         spin_unlock_irqrestore(&nvram_lock, flags);
 105                         return -EIO;
 106                 }
 107
 108                 p += len;
 109                 i += len;
 110         }
 111         spin_unlock_irqrestore(&nvram_lock, flags);
 112
 113         *index = i;
 114         return p - buf;
 115 }
 116
 117 static ssize_t pSeries_nvram_get_size(void)
 118 {
 119         return nvram_size ? nvram_size : -ENODEV;
 120 }
 121
 122 int __init pSeries_nvram_init(void)
 123 {
 124         struct device_node *nvram;
 125         const unsigned int *nbytes_p;
 126         unsigned int proplen;
 127
 128         nvram = of_find_node_by_type(NULL, "nvram");
 129         if (nvram == NULL)
 130                 return -ENODEV;
 131
 132         nbytes_p = of_get_property(nvram, "#bytes", &proplen);
 133         if (nbytes_p == NULL || proplen != sizeof(unsigned int)) {
 134                 of_node_put(nvram);
 135                 return -EIO;
 136         }
 137
 138         nvram_size = *nbytes_p;
 139
 140         nvram_fetch = rtas_token("nvram-fetch");
 141         nvram_store = rtas_token("nvram-store");
 142         printk(KERN_INFO "PPC64 nvram contains %d bytes\n", nvram_size);
 143         of_node_put(nvram);
 144
 145         ppc_md.nvram_read       = pSeries_nvram_read;
 146         ppc_md.nvram_write      = pSeries_nvram_write;
 147         ppc_md.nvram_size       = pSeries_nvram_get_size;
 148
 149         return 0;
 150 }