1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0-or-later
2*4882a593Smuzhiyun /*
3*4882a593Smuzhiyun * c 2001 PPC 64 Team, IBM Corp
4*4882a593Smuzhiyun *
5*4882a593Smuzhiyun * /dev/nvram driver for PPC
6*4882a593Smuzhiyun */
7*4882a593Smuzhiyun
8*4882a593Smuzhiyun #include <linux/kernel.h>
9*4882a593Smuzhiyun #include <linux/module.h>
10*4882a593Smuzhiyun #include <linux/init.h>
11*4882a593Smuzhiyun #include <linux/spinlock.h>
12*4882a593Smuzhiyun #include <linux/uaccess.h>
13*4882a593Smuzhiyun #include <asm/prom.h>
14*4882a593Smuzhiyun #include <asm/machdep.h>
15*4882a593Smuzhiyun #include <asm/rtas.h>
16*4882a593Smuzhiyun #include "chrp.h"
17*4882a593Smuzhiyun
18*4882a593Smuzhiyun static unsigned int nvram_size;
19*4882a593Smuzhiyun static unsigned char nvram_buf[4];
20*4882a593Smuzhiyun static DEFINE_SPINLOCK(nvram_lock);
21*4882a593Smuzhiyun
chrp_nvram_read_val(int addr)22*4882a593Smuzhiyun static unsigned char chrp_nvram_read_val(int addr)
23*4882a593Smuzhiyun {
24*4882a593Smuzhiyun unsigned int done;
25*4882a593Smuzhiyun unsigned long flags;
26*4882a593Smuzhiyun unsigned char ret;
27*4882a593Smuzhiyun
28*4882a593Smuzhiyun if (addr >= nvram_size) {
29*4882a593Smuzhiyun printk(KERN_DEBUG "%s: read addr %d > nvram_size %u\n",
30*4882a593Smuzhiyun current->comm, addr, nvram_size);
31*4882a593Smuzhiyun return 0xff;
32*4882a593Smuzhiyun }
33*4882a593Smuzhiyun spin_lock_irqsave(&nvram_lock, flags);
34*4882a593Smuzhiyun if ((rtas_call(rtas_token("nvram-fetch"), 3, 2, &done, addr,
35*4882a593Smuzhiyun __pa(nvram_buf), 1) != 0) || 1 != done)
36*4882a593Smuzhiyun ret = 0xff;
37*4882a593Smuzhiyun else
38*4882a593Smuzhiyun ret = nvram_buf[0];
39*4882a593Smuzhiyun spin_unlock_irqrestore(&nvram_lock, flags);
40*4882a593Smuzhiyun
41*4882a593Smuzhiyun return ret;
42*4882a593Smuzhiyun }
43*4882a593Smuzhiyun
chrp_nvram_write_val(int addr,unsigned char val)44*4882a593Smuzhiyun static void chrp_nvram_write_val(int addr, unsigned char val)
45*4882a593Smuzhiyun {
46*4882a593Smuzhiyun unsigned int done;
47*4882a593Smuzhiyun unsigned long flags;
48*4882a593Smuzhiyun
49*4882a593Smuzhiyun if (addr >= nvram_size) {
50*4882a593Smuzhiyun printk(KERN_DEBUG "%s: write addr %d > nvram_size %u\n",
51*4882a593Smuzhiyun current->comm, addr, nvram_size);
52*4882a593Smuzhiyun return;
53*4882a593Smuzhiyun }
54*4882a593Smuzhiyun spin_lock_irqsave(&nvram_lock, flags);
55*4882a593Smuzhiyun nvram_buf[0] = val;
56*4882a593Smuzhiyun if ((rtas_call(rtas_token("nvram-store"), 3, 2, &done, addr,
57*4882a593Smuzhiyun __pa(nvram_buf), 1) != 0) || 1 != done)
58*4882a593Smuzhiyun printk(KERN_DEBUG "rtas IO error storing 0x%02x at %d", val, addr);
59*4882a593Smuzhiyun spin_unlock_irqrestore(&nvram_lock, flags);
60*4882a593Smuzhiyun }
61*4882a593Smuzhiyun
chrp_nvram_size(void)62*4882a593Smuzhiyun static ssize_t chrp_nvram_size(void)
63*4882a593Smuzhiyun {
64*4882a593Smuzhiyun return nvram_size;
65*4882a593Smuzhiyun }
66*4882a593Smuzhiyun
chrp_nvram_init(void)67*4882a593Smuzhiyun void __init chrp_nvram_init(void)
68*4882a593Smuzhiyun {
69*4882a593Smuzhiyun struct device_node *nvram;
70*4882a593Smuzhiyun const __be32 *nbytes_p;
71*4882a593Smuzhiyun unsigned int proplen;
72*4882a593Smuzhiyun
73*4882a593Smuzhiyun nvram = of_find_node_by_type(NULL, "nvram");
74*4882a593Smuzhiyun if (nvram == NULL)
75*4882a593Smuzhiyun return;
76*4882a593Smuzhiyun
77*4882a593Smuzhiyun nbytes_p = of_get_property(nvram, "#bytes", &proplen);
78*4882a593Smuzhiyun if (nbytes_p == NULL || proplen != sizeof(unsigned int)) {
79*4882a593Smuzhiyun of_node_put(nvram);
80*4882a593Smuzhiyun return;
81*4882a593Smuzhiyun }
82*4882a593Smuzhiyun
83*4882a593Smuzhiyun nvram_size = be32_to_cpup(nbytes_p);
84*4882a593Smuzhiyun
85*4882a593Smuzhiyun printk(KERN_INFO "CHRP nvram contains %u bytes\n", nvram_size);
86*4882a593Smuzhiyun of_node_put(nvram);
87*4882a593Smuzhiyun
88*4882a593Smuzhiyun ppc_md.nvram_read_val = chrp_nvram_read_val;
89*4882a593Smuzhiyun ppc_md.nvram_write_val = chrp_nvram_write_val;
90*4882a593Smuzhiyun ppc_md.nvram_size = chrp_nvram_size;
91*4882a593Smuzhiyun
92*4882a593Smuzhiyun return;
93*4882a593Smuzhiyun }
94*4882a593Smuzhiyun
95*4882a593Smuzhiyun MODULE_LICENSE("GPL v2");
96