opal-nvram.c

  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
 19static unsigned int nvram_size;
 20
 21static ssize_t opal_nvram_size(void)
 22{
 23	return nvram_size;
 24}
 25
 26static 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 */
 47static 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
 81static 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}
 88machine_arch_initcall(powernv, opal_nvram_init_log_partitions);
 89
 90void __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