arch/powerpc/platforms/chrp/nvram.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  c 2001 PPC 64 Team, IBM Corp
   4  *
   5  * /dev/nvram driver for PPC
   6  */
   7
   8 #include <linux/kernel.h>
   9 #include <linux/module.h>
  10 #include <linux/init.h>
  11 #include <linux/spinlock.h>
  12 #include <linux/uaccess.h>
  13 #include <asm/prom.h>
  14 #include <asm/machdep.h>
  15 #include <asm/rtas.h>
  16 #include "chrp.h"
  17
  18 static unsigned int nvram_size;
  19 static unsigned char nvram_buf[4];
  20 static DEFINE_SPINLOCK(nvram_lock);
  21
  22 static unsigned char chrp_nvram_read_val(int addr)
  23 {
  24         unsigned int done;
  25         unsigned long flags;
  26         unsigned char ret;
  27
  28         if (addr >= nvram_size) {
  29                 printk(KERN_DEBUG "%s: read addr %d > nvram_size %u\n",
  30                        current->comm, addr, nvram_size);
  31                 return 0xff;
  32         }
  33         spin_lock_irqsave(&nvram_lock, flags);
  34         if ((rtas_call(rtas_token("nvram-fetch"), 3, 2, &done, addr,
  35                        __pa(nvram_buf), 1) != 0) || 1 != done)
  36                 ret = 0xff;
  37         else
  38                 ret = nvram_buf[0];
  39         spin_unlock_irqrestore(&nvram_lock, flags);
  40
  41         return ret;
  42 }
  43
  44 static void chrp_nvram_write_val(int addr, unsigned char val)
  45 {
  46         unsigned int done;
  47         unsigned long flags;
  48
  49         if (addr >= nvram_size) {
  50                 printk(KERN_DEBUG "%s: write addr %d > nvram_size %u\n",
  51                        current->comm, addr, nvram_size);
  52                 return;
  53         }
  54         spin_lock_irqsave(&nvram_lock, flags);
  55         nvram_buf[0] = val;
  56         if ((rtas_call(rtas_token("nvram-store"), 3, 2, &done, addr,
  57                        __pa(nvram_buf), 1) != 0) || 1 != done)
  58                 printk(KERN_DEBUG "rtas IO error storing 0x%02x at %d", val, addr);
  59         spin_unlock_irqrestore(&nvram_lock, flags);
  60 }
  61
  62 static ssize_t chrp_nvram_size(void)
  63 {
  64         return nvram_size;
  65 }
  66
  67 void __init chrp_nvram_init(void)
  68 {
  69         struct device_node *nvram;
  70         const __be32 *nbytes_p;
  71         unsigned int proplen;
  72
  73         nvram = of_find_node_by_type(NULL, "nvram");
  74         if (nvram == NULL)
  75                 return;
  76
  77         nbytes_p = of_get_property(nvram, "#bytes", &proplen);
  78         if (nbytes_p == NULL || proplen != sizeof(unsigned int)) {
  79                 of_node_put(nvram);
  80                 return;
  81         }
  82
  83         nvram_size = be32_to_cpup(nbytes_p);
  84
  85         printk(KERN_INFO "CHRP nvram contains %u bytes\n", nvram_size);
  86         of_node_put(nvram);
  87
  88         ppc_md.nvram_read_val  = chrp_nvram_read_val;
  89         ppc_md.nvram_write_val = chrp_nvram_write_val;
  90         ppc_md.nvram_size      = chrp_nvram_size;
  91
  92         return;
  93 }
  94
  95 MODULE_LICENSE("GPL v2");