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