/*
   * RAM Oops/Panic logger
   *
   * Copyright (C) 2010 Marco Stornelli <marco.stornelli@gmail.com>
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License
   * version 2 as published by the Free Software Foundation.
   *
   * This program is distributed in the hope that it will be useful, but
   * WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
   * 02110-1301 USA
   *
   */

  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

  #include <linux/kernel.h>

  #include <linux/err.h>

  #include <linux/module.h>
  #include <linux/kmsg_dump.h>
  #include <linux/time.h>

  #include <linux/err.h>

  #include <linux/io.h>
  #include <linux/ioport.h>

  #include <linux/platform_device.h>

  #include <linux/slab.h>

  #include <linux/ramoops.h>

  
  #define RAMOOPS_KERNMSG_HDR "===="

  #define MIN_MEM_SIZE 4096UL

  static ulong record_size = MIN_MEM_SIZE;
  module_param(record_size, ulong, 0400);
  MODULE_PARM_DESC(record_size,
  		"size of each dump done on oops/panic");

  
  static ulong mem_address;
  module_param(mem_address, ulong, 0400);
  MODULE_PARM_DESC(mem_address,
  		"start of reserved RAM used to store oops/panic logs");
  
  static ulong mem_size;
  module_param(mem_size, ulong, 0400);
  MODULE_PARM_DESC(mem_size,
  		"size of reserved RAM used to store oops/panic logs");
  
  static int dump_oops = 1;
  module_param(dump_oops, int, 0600);
  MODULE_PARM_DESC(dump_oops,
  		"set to 1 to dump oopses, 0 to only dump panics (default 1)");
  
  static struct ramoops_context {
  	struct kmsg_dumper dump;
  	void *virt_addr;
  	phys_addr_t phys_addr;
  	unsigned long size;

  	unsigned long record_size;

  	int dump_oops;

  	int count;
  	int max_count;
  } oops_cxt;

  static struct platform_device *dummy;
  static struct ramoops_platform_data *dummy_data;

  static void ramoops_do_dump(struct kmsg_dumper *dumper,
  		enum kmsg_dump_reason reason, const char *s1, unsigned long l1,
  		const char *s2, unsigned long l2)
  {
  	struct ramoops_context *cxt = container_of(dumper,
  			struct ramoops_context, dump);
  	unsigned long s1_start, s2_start;
  	unsigned long l1_cpy, l2_cpy;

  	int res, hdr_size;
  	char *buf, *buf_orig;

  	struct timeval timestamp;

  	if (reason != KMSG_DUMP_OOPS &&

  	    reason != KMSG_DUMP_PANIC)

  		return;

  	/* Only dump oopses if dump_oops is set */

  	if (reason == KMSG_DUMP_OOPS && !cxt->dump_oops)

  		return;

  	buf = cxt->virt_addr + (cxt->count * cxt->record_size);

  	buf_orig = buf;

  	memset(buf, '\0', cxt->record_size);

  	res = sprintf(buf, "%s", RAMOOPS_KERNMSG_HDR);
  	buf += res;
  	do_gettimeofday(&timestamp);
  	res = sprintf(buf, "%lu.%lu
  ", (long)timestamp.tv_sec, (long)timestamp.tv_usec);
  	buf += res;

  	hdr_size = buf - buf_orig;

  	l2_cpy = min(l2, cxt->record_size - hdr_size);
  	l1_cpy = min(l1, cxt->record_size - hdr_size - l2_cpy);

  
  	s2_start = l2 - l2_cpy;
  	s1_start = l1 - l1_cpy;
  
  	memcpy(buf, s1 + s1_start, l1_cpy);
  	memcpy(buf + l1_cpy, s2 + s2_start, l2_cpy);
  
  	cxt->count = (cxt->count + 1) % cxt->max_count;
  }

  static int __init ramoops_probe(struct platform_device *pdev)

  {

  	struct ramoops_platform_data *pdata = pdev->dev.platform_data;

  	struct ramoops_context *cxt = &oops_cxt;
  	int err = -EINVAL;

  	if (!pdata->mem_size || !pdata->record_size) {
  		pr_err("The memory size and the record size must be "
  			"non-zero
  ");

  		goto fail3;
  	}

  	pdata->mem_size = rounddown_pow_of_two(pdata->mem_size);
  	pdata->record_size = rounddown_pow_of_two(pdata->record_size);

  	/* Check for the minimum memory size */
  	if (pdata->mem_size < MIN_MEM_SIZE &&
  			pdata->record_size < MIN_MEM_SIZE) {
  		pr_err("memory size too small, minium is %lu
  ", MIN_MEM_SIZE);

  		goto fail3;
  	}

  	if (pdata->mem_size < pdata->record_size) {
  		pr_err("The memory size must be larger than the "
  			"records size
  ");
  		goto fail3;
  	}
  
  	cxt->max_count = pdata->mem_size / pdata->record_size;

  	cxt->count = 0;

  	cxt->size = pdata->mem_size;
  	cxt->phys_addr = pdata->mem_address;

  	cxt->record_size = pdata->record_size;

  	cxt->dump_oops = pdata->dump_oops;

  
  	if (!request_mem_region(cxt->phys_addr, cxt->size, "ramoops")) {

  		pr_err("request mem region failed
  ");

  		err = -EINVAL;
  		goto fail3;
  	}
  
  	cxt->virt_addr = ioremap(cxt->phys_addr,  cxt->size);
  	if (!cxt->virt_addr) {

  		pr_err("ioremap failed
  ");

  		goto fail2;
  	}
  
  	cxt->dump.dump = ramoops_do_dump;
  	err = kmsg_dump_register(&cxt->dump);
  	if (err) {

  		pr_err("registering kmsg dumper failed
  ");

  		goto fail1;
  	}

  	/*
  	 * Update the module parameter variables as well so they are visible
  	 * through /sys/module/ramoops/parameters/
  	 */
  	mem_size = pdata->mem_size;
  	mem_address = pdata->mem_address;
  	record_size = pdata->record_size;
  	dump_oops = pdata->dump_oops;

  	return 0;
  
  fail1:
  	iounmap(cxt->virt_addr);
  fail2:
  	release_mem_region(cxt->phys_addr, cxt->size);
  fail3:
  	return err;
  }

  static int __exit ramoops_remove(struct platform_device *pdev)

  {
  	struct ramoops_context *cxt = &oops_cxt;
  
  	if (kmsg_dump_unregister(&cxt->dump) < 0)

  		pr_warn("could not unregister kmsg_dumper
  ");

  
  	iounmap(cxt->virt_addr);
  	release_mem_region(cxt->phys_addr, cxt->size);

  	return 0;

  }

  static struct platform_driver ramoops_driver = {
  	.remove		= __exit_p(ramoops_remove),
  	.driver		= {
  		.name	= "ramoops",
  		.owner	= THIS_MODULE,
  	},
  };
  
  static int __init ramoops_init(void)
  {

  	int ret;
  	ret = platform_driver_probe(&ramoops_driver, ramoops_probe);
  	if (ret == -ENODEV) {
  		/*
  		 * If we didn't find a platform device, we use module parameters
  		 * building platform data on the fly.
  		 */

  		pr_info("platform device not found, using module parameters
  ");

  		dummy_data = kzalloc(sizeof(struct ramoops_platform_data),
  				     GFP_KERNEL);
  		if (!dummy_data)
  			return -ENOMEM;
  		dummy_data->mem_size = mem_size;
  		dummy_data->mem_address = mem_address;

  		dummy_data->record_size = record_size;

  		dummy_data->dump_oops = dump_oops;

  		dummy = platform_create_bundle(&ramoops_driver, ramoops_probe,
  			NULL, 0, dummy_data,
  			sizeof(struct ramoops_platform_data));
  
  		if (IS_ERR(dummy))
  			ret = PTR_ERR(dummy);
  		else
  			ret = 0;
  	}
  
  	return ret;

  }
  
  static void __exit ramoops_exit(void)
  {
  	platform_driver_unregister(&ramoops_driver);

  	kfree(dummy_data);

  }

  
  module_init(ramoops_init);
  module_exit(ramoops_exit);
  
  MODULE_LICENSE("GPL");
  MODULE_AUTHOR("Marco Stornelli <marco.stornelli@gmail.com>");
  MODULE_DESCRIPTION("RAM Oops/Panic logger/driver");