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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* c 2001 PPC 64 Team, IBM Corp
*
* /dev/nvram driver for PPC
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/uaccess.h>
#include <linux/of.h>
#include <asm/machdep.h>
#include <asm/rtas.h>
#include "chrp.h"
static unsigned int nvram_size;
static unsigned char nvram_buf[4];
static DEFINE_SPINLOCK(nvram_lock);
static unsigned char chrp_nvram_read_val(int addr)
{
unsigned int done;
unsigned long flags;
unsigned char ret;
if (addr >= nvram_size) {
printk(KERN_DEBUG "%s: read addr %d > nvram_size %u\n",
current->comm, addr, nvram_size);
return 0xff;
}
spin_lock_irqsave(&nvram_lock, flags);
if ((rtas_call(rtas_token("nvram-fetch"), 3, 2, &done, addr,
__pa(nvram_buf), 1) != 0) || 1 != done)
ret = 0xff;
else
ret = nvram_buf[0];
spin_unlock_irqrestore(&nvram_lock, flags);
return ret;
}
static void chrp_nvram_write_val(int addr, unsigned char val)
{
unsigned int done;
unsigned long flags;
if (addr >= nvram_size) {
printk(KERN_DEBUG "%s: write addr %d > nvram_size %u\n",
current->comm, addr, nvram_size);
return;
}
spin_lock_irqsave(&nvram_lock, flags);
nvram_buf[0] = val;
if ((rtas_call(rtas_token("nvram-store"), 3, 2, &done, addr,
__pa(nvram_buf), 1) != 0) || 1 != done)
printk(KERN_DEBUG "rtas IO error storing 0x%02x at %d", val, addr);
spin_unlock_irqrestore(&nvram_lock, flags);
}
static ssize_t chrp_nvram_size(void)
{
return nvram_size;
}
void __init chrp_nvram_init(void)
{
struct device_node *nvram;
const __be32 *nbytes_p;
unsigned int proplen;
nvram = of_find_node_by_type(NULL, "nvram");
if (nvram == NULL)
return;
nbytes_p = of_get_property(nvram, "#bytes", &proplen);
if (nbytes_p == NULL || proplen != sizeof(unsigned int)) {
of_node_put(nvram);
return;
}
nvram_size = be32_to_cpup(nbytes_p);
printk(KERN_INFO "CHRP nvram contains %u bytes\n", nvram_size);
of_node_put(nvram);
ppc_md.nvram_read_val = chrp_nvram_read_val;
ppc_md.nvram_write_val = chrp_nvram_write_val;
ppc_md.nvram_size = chrp_nvram_size;
return;
}
MODULE_LICENSE("GPL v2");
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