// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * PowerNV nvram code.
 *
 * Copyright 2011 IBM Corp.
 */

#define DEBUG

#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/of.h>

#include <asm/opal.h>
#include <asm/nvram.h>
#include <asm/machdep.h>

static unsigned int nvram_size;

static ssize_t opal_nvram_size(void)
{
        return nvram_size;
}

static ssize_t opal_nvram_read(char *buf, size_t count, loff_t *index)
{
        s64 rc;
        int off;

        if (*index >= nvram_size)
                return 0;
        off = *index;
        if ((off + count) > nvram_size)
                count = nvram_size - off;
        rc = opal_read_nvram(__pa(buf), count, off);
        if (rc != OPAL_SUCCESS)
                return -EIO;
        *index += count;
        return count;
}

/*
 * This can be called in the panic path with interrupts off, so use
 * mdelay in that case.
 */
static ssize_t opal_nvram_write(char *buf, size_t count, loff_t *index)
{
        s64 rc = OPAL_BUSY;
        int off;

        if (*index >= nvram_size)
                return 0;
        off = *index;
        if ((off + count) > nvram_size)
                count = nvram_size - off;

        while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) {
                rc = opal_write_nvram(__pa(buf), count, off);
                if (rc == OPAL_BUSY_EVENT) {
                        if (in_interrupt() || irqs_disabled())
                                mdelay(OPAL_BUSY_DELAY_MS);
                        else
                                msleep(OPAL_BUSY_DELAY_MS);
                        opal_poll_events(NULL);
                } else if (rc == OPAL_BUSY) {
                        if (in_interrupt() || irqs_disabled())
                                mdelay(OPAL_BUSY_DELAY_MS);
                        else
                                msleep(OPAL_BUSY_DELAY_MS);
                }
        }

        if (rc)
                return -EIO;

        *index += count;
        return count;
}

static int __init opal_nvram_init_log_partitions(void)
{
        /* Scan nvram for partitions */
        nvram_scan_partitions();
        nvram_init_oops_partition(0);
        return 0;
}
machine_arch_initcall(powernv, opal_nvram_init_log_partitions);

void __init opal_nvram_init(void)
{
        struct device_node *np;
        const __be32 *nbytes_p;

        np = of_find_compatible_node(NULL, NULL, "ibm,opal-nvram");
        if (np == NULL)
                return;

        nbytes_p = of_get_property(np, "#bytes", NULL);
        if (!nbytes_p) {
                of_node_put(np);
                return;
        }
        nvram_size = be32_to_cpup(nbytes_p);

        pr_info("OPAL nvram setup, %u bytes\n", nvram_size);
        of_node_put(np);

        ppc_md.nvram_read = opal_nvram_read;
        ppc_md.nvram_write = opal_nvram_write;
        ppc_md.nvram_size = opal_nvram_size;
}