1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * PowerNV nvram code.
4  *
5  * Copyright 2011 IBM Corp.
6  */
7 
8 #define DEBUG
9 
10 #include <linux/delay.h>
11 #include <linux/kernel.h>
12 #include <linux/init.h>
13 #include <linux/of.h>
14 
15 #include <asm/opal.h>
16 #include <asm/nvram.h>
17 #include <asm/machdep.h>
18 
19 static unsigned int nvram_size;
20 
21 static ssize_t opal_nvram_size(void)
22 {
23 	return nvram_size;
24 }
25 
26 static ssize_t opal_nvram_read(char *buf, size_t count, loff_t *index)
27 {
28 	s64 rc;
29 	int off;
30 
31 	if (*index >= nvram_size)
32 		return 0;
33 	off = *index;
34 	if ((off + count) > nvram_size)
35 		count = nvram_size - off;
36 	rc = opal_read_nvram(__pa(buf), count, off);
37 	if (rc != OPAL_SUCCESS)
38 		return -EIO;
39 	*index += count;
40 	return count;
41 }
42 
43 /*
44  * This can be called in the panic path with interrupts off, so use
45  * mdelay in that case.
46  */
47 static ssize_t opal_nvram_write(char *buf, size_t count, loff_t *index)
48 {
49 	s64 rc = OPAL_BUSY;
50 	int off;
51 
52 	if (*index >= nvram_size)
53 		return 0;
54 	off = *index;
55 	if ((off + count) > nvram_size)
56 		count = nvram_size - off;
57 
58 	while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) {
59 		rc = opal_write_nvram(__pa(buf), count, off);
60 		if (rc == OPAL_BUSY_EVENT) {
61 			if (in_interrupt() || irqs_disabled())
62 				mdelay(OPAL_BUSY_DELAY_MS);
63 			else
64 				msleep(OPAL_BUSY_DELAY_MS);
65 			opal_poll_events(NULL);
66 		} else if (rc == OPAL_BUSY) {
67 			if (in_interrupt() || irqs_disabled())
68 				mdelay(OPAL_BUSY_DELAY_MS);
69 			else
70 				msleep(OPAL_BUSY_DELAY_MS);
71 		}
72 	}
73 
74 	if (rc)
75 		return -EIO;
76 
77 	*index += count;
78 	return count;
79 }
80 
81 static int __init opal_nvram_init_log_partitions(void)
82 {
83 	/* Scan nvram for partitions */
84 	nvram_scan_partitions();
85 	nvram_init_oops_partition(0);
86 	return 0;
87 }
88 machine_arch_initcall(powernv, opal_nvram_init_log_partitions);
89 
90 void __init opal_nvram_init(void)
91 {
92 	struct device_node *np;
93 	const __be32 *nbytes_p;
94 
95 	np = of_find_compatible_node(NULL, NULL, "ibm,opal-nvram");
96 	if (np == NULL)
97 		return;
98 
99 	nbytes_p = of_get_property(np, "#bytes", NULL);
100 	if (!nbytes_p) {
101 		of_node_put(np);
102 		return;
103 	}
104 	nvram_size = be32_to_cpup(nbytes_p);
105 
106 	pr_info("OPAL nvram setup, %u bytes\n", nvram_size);
107 	of_node_put(np);
108 
109 	ppc_md.nvram_read = opal_nvram_read;
110 	ppc_md.nvram_write = opal_nvram_write;
111 	ppc_md.nvram_size = opal_nvram_size;
112 }
113 
114