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/module.h>
15 #include <linux/init.h>
16 #include <linux/spinlock.h>
17 #include <linux/uaccess.h>
18 #include <asm/prom.h>
19 #include <asm/machdep.h>
20 #include <asm/rtas.h>
21 #include "chrp.h"
22 
23 static unsigned int nvram_size;
24 static unsigned char nvram_buf[4];
25 static DEFINE_SPINLOCK(nvram_lock);
26 
27 static unsigned char chrp_nvram_read(int addr)
28 {
29 	unsigned int done;
30 	unsigned long flags;
31 	unsigned char ret;
32 
33 	if (addr >= nvram_size) {
34 		printk(KERN_DEBUG "%s: read addr %d > nvram_size %u\n",
35 		       current->comm, addr, nvram_size);
36 		return 0xff;
37 	}
38 	spin_lock_irqsave(&nvram_lock, flags);
39 	if ((rtas_call(rtas_token("nvram-fetch"), 3, 2, &done, addr,
40 		       __pa(nvram_buf), 1) != 0) || 1 != done)
41 		ret = 0xff;
42 	else
43 		ret = nvram_buf[0];
44 	spin_unlock_irqrestore(&nvram_lock, flags);
45 
46 	return ret;
47 }
48 
49 static void chrp_nvram_write(int addr, unsigned char val)
50 {
51 	unsigned int done;
52 	unsigned long flags;
53 
54 	if (addr >= nvram_size) {
55 		printk(KERN_DEBUG "%s: write addr %d > nvram_size %u\n",
56 		       current->comm, addr, nvram_size);
57 		return;
58 	}
59 	spin_lock_irqsave(&nvram_lock, flags);
60 	nvram_buf[0] = val;
61 	if ((rtas_call(rtas_token("nvram-store"), 3, 2, &done, addr,
62 		       __pa(nvram_buf), 1) != 0) || 1 != done)
63 		printk(KERN_DEBUG "rtas IO error storing 0x%02x at %d", val, addr);
64 	spin_unlock_irqrestore(&nvram_lock, flags);
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;
89 	ppc_md.nvram_write_val = chrp_nvram_write;
90 
91 	return;
92 }
93 
94 MODULE_LICENSE("GPL v2");
95