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