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kernel/linux-rt-4.4.41/arch/powerpc/platforms/chrp/nvram.c 2.21 KB
5113f6f70   김현기   kernel add
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  /*
   *  c 2001 PPC 64 Team, IBM Corp
   *
   *      This program is free software; you can redistribute it and/or
   *      modify it under the terms of the GNU General Public License
   *      as published by the Free Software Foundation; either version
   *      2 of the License, or (at your option) any later version.
   *
   * /dev/nvram driver for PPC
   *
   */
  
  #include <linux/kernel.h>
  #include <linux/init.h>
  #include <linux/spinlock.h>
  #include <asm/uaccess.h>
  #include <asm/prom.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(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
  ",
  		       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(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
  ",
  		       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);
  }
  
  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
  ", nvram_size);
  	of_node_put(nvram);
  
  	ppc_md.nvram_read_val = chrp_nvram_read;
  	ppc_md.nvram_write_val = chrp_nvram_write;
  
  	return;
  }