/*
   *  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 PPC64
   *
   * This perhaps should live in drivers/char
   */
  
  
  #include <linux/types.h>
  #include <linux/errno.h>
  #include <linux/init.h>
  #include <linux/spinlock.h>
  #include <linux/slab.h>
  #include <linux/kmsg_dump.h>
  #include <linux/pstore.h>
  #include <linux/ctype.h>
  #include <asm/uaccess.h>
  #include <asm/nvram.h>
  #include <asm/rtas.h>
  #include <asm/prom.h>
  #include <asm/machdep.h>
  
  /* Max bytes to read/write in one go */
  #define NVRW_CNT 0x20
  
  static unsigned int nvram_size;
  static int nvram_fetch, nvram_store;
  static char nvram_buf[NVRW_CNT];	/* assume this is in the first 4GB */
  static DEFINE_SPINLOCK(nvram_lock);
  
  /* See clobbering_unread_rtas_event() */
  #define NVRAM_RTAS_READ_TIMEOUT 5		/* seconds */
  static time64_t last_unread_rtas_event;		/* timestamp */
  
  #ifdef CONFIG_PSTORE
  time64_t last_rtas_event;
  #endif
  
  static ssize_t pSeries_nvram_read(char *buf, size_t count, loff_t *index)
  {
  	unsigned int i;
  	unsigned long len;
  	int done;
  	unsigned long flags;
  	char *p = buf;
  
  
  	if (nvram_size == 0 || nvram_fetch == RTAS_UNKNOWN_SERVICE)
  		return -ENODEV;
  
  	if (*index >= nvram_size)
  		return 0;
  
  	i = *index;
  	if (i + count > nvram_size)
  		count = nvram_size - i;
  
  	spin_lock_irqsave(&nvram_lock, flags);
  
  	for (; count != 0; count -= len) {
  		len = count;
  		if (len > NVRW_CNT)
  			len = NVRW_CNT;
  		
  		if ((rtas_call(nvram_fetch, 3, 2, &done, i, __pa(nvram_buf),
  			       len) != 0) || len != done) {
  			spin_unlock_irqrestore(&nvram_lock, flags);
  			return -EIO;
  		}
  		
  		memcpy(p, nvram_buf, len);
  
  		p += len;
  		i += len;
  	}
  
  	spin_unlock_irqrestore(&nvram_lock, flags);
  	
  	*index = i;
  	return p - buf;
  }
  
  static ssize_t pSeries_nvram_write(char *buf, size_t count, loff_t *index)
  {
  	unsigned int i;
  	unsigned long len;
  	int done;
  	unsigned long flags;
  	const char *p = buf;
  
  	if (nvram_size == 0 || nvram_store == RTAS_UNKNOWN_SERVICE)
  		return -ENODEV;
  
  	if (*index >= nvram_size)
  		return 0;
  
  	i = *index;
  	if (i + count > nvram_size)
  		count = nvram_size - i;
  
  	spin_lock_irqsave(&nvram_lock, flags);
  
  	for (; count != 0; count -= len) {
  		len = count;
  		if (len > NVRW_CNT)
  			len = NVRW_CNT;
  
  		memcpy(nvram_buf, p, len);
  
  		if ((rtas_call(nvram_store, 3, 2, &done, i, __pa(nvram_buf),
  			       len) != 0) || len != done) {
  			spin_unlock_irqrestore(&nvram_lock, flags);
  			return -EIO;
  		}
  		
  		p += len;
  		i += len;
  	}
  	spin_unlock_irqrestore(&nvram_lock, flags);
  	
  	*index = i;
  	return p - buf;
  }
  
  static ssize_t pSeries_nvram_get_size(void)
  {
  	return nvram_size ? nvram_size : -ENODEV;
  }
  
  /* nvram_write_error_log
   *
   * We need to buffer the error logs into nvram to ensure that we have
   * the failure information to decode.
   */
  int nvram_write_error_log(char * buff, int length,
                            unsigned int err_type, unsigned int error_log_cnt)
  {
  	int rc = nvram_write_os_partition(&rtas_log_partition, buff, length,
  						err_type, error_log_cnt);
  	if (!rc) {
  		last_unread_rtas_event = ktime_get_real_seconds();
  #ifdef CONFIG_PSTORE
  		last_rtas_event = ktime_get_real_seconds();
  #endif
  	}
  
  	return rc;
  }
  
  /* nvram_read_error_log
   *
   * Reads nvram for error log for at most 'length'
   */
  int nvram_read_error_log(char *buff, int length,
  			unsigned int *err_type, unsigned int *error_log_cnt)
  {
  	return nvram_read_partition(&rtas_log_partition, buff, length,
  						err_type, error_log_cnt);
  }
  
  /* This doesn't actually zero anything, but it sets the event_logged
   * word to tell that this event is safely in syslog.
   */
  int nvram_clear_error_log(void)
  {
  	loff_t tmp_index;
  	int clear_word = ERR_FLAG_ALREADY_LOGGED;
  	int rc;
  
  	if (rtas_log_partition.index == -1)
  		return -1;
  
  	tmp_index = rtas_log_partition.index;
  	
  	rc = ppc_md.nvram_write((char *)&clear_word, sizeof(int), &tmp_index);
  	if (rc <= 0) {
  		printk(KERN_ERR "nvram_clear_error_log: Failed nvram_write (%d)
  ", rc);
  		return rc;
  	}
  	last_unread_rtas_event = 0;
  
  	return 0;
  }
  
  /*
   * Are we using the ibm,rtas-log for oops/panic reports?  And if so,
   * would logging this oops/panic overwrite an RTAS event that rtas_errd
   * hasn't had a chance to read and process?  Return 1 if so, else 0.
   *
   * We assume that if rtas_errd hasn't read the RTAS event in
   * NVRAM_RTAS_READ_TIMEOUT seconds, it's probably not going to.
   */
  int clobbering_unread_rtas_event(void)
  {
  	return (oops_log_partition.index == rtas_log_partition.index
  		&& last_unread_rtas_event
  		&& ktime_get_real_seconds() - last_unread_rtas_event <=
  						NVRAM_RTAS_READ_TIMEOUT);
  }
  
  static int __init pseries_nvram_init_log_partitions(void)
  {
  	int rc;
  
  	/* Scan nvram for partitions */
  	nvram_scan_partitions();
  
  	rc = nvram_init_os_partition(&rtas_log_partition);
  	nvram_init_oops_partition(rc == 0);
  	return 0;
  }
  machine_arch_initcall(pseries, pseries_nvram_init_log_partitions);
  
  int __init pSeries_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 -ENODEV;
  
  	nbytes_p = of_get_property(nvram, "#bytes", &proplen);
  	if (nbytes_p == NULL || proplen != sizeof(unsigned int)) {
  		of_node_put(nvram);
  		return -EIO;
  	}
  
  	nvram_size = be32_to_cpup(nbytes_p);
  
  	nvram_fetch = rtas_token("nvram-fetch");
  	nvram_store = rtas_token("nvram-store");
  	printk(KERN_INFO "PPC64 nvram contains %d bytes
  ", nvram_size);
  	of_node_put(nvram);
  
  	ppc_md.nvram_read	= pSeries_nvram_read;
  	ppc_md.nvram_write	= pSeries_nvram_write;
  	ppc_md.nvram_size	= pSeries_nvram_get_size;
  
  	return 0;
  }