/*
   *  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.
   *
   *  Copyright (C) 2004 Liu Peng Infineon IFAP DC COM CPE

   *  Copyright (C) 2010 John Crispin <john@phrozen.org>

   */

  #include <linux/err.h>

  #include <linux/module.h>
  #include <linux/types.h>
  #include <linux/kernel.h>
  #include <linux/io.h>
  #include <linux/slab.h>

  #include <linux/mtd/mtd.h>
  #include <linux/mtd/map.h>
  #include <linux/mtd/partitions.h>
  #include <linux/mtd/cfi.h>
  #include <linux/platform_device.h>
  #include <linux/mtd/physmap.h>

  #include <linux/of.h>

  
  #include <lantiq_soc.h>

  
  /*
   * The NOR flash is connected to the same external bus unit (EBU) as PCI.
   * To make PCI work we need to enable the endianness swapping for the address
   * written to the EBU. This endianness swapping works for PCI correctly but
   * fails for attached NOR devices. To workaround this we need to use a complex
   * map. The workaround involves swapping all addresses whilst probing the chip.
   * Once probing is complete we stop swapping the addresses but swizzle the
   * unlock addresses to ensure that access to the NOR device works correctly.
   */
  
  enum {
  	LTQ_NOR_PROBING,
  	LTQ_NOR_NORMAL
  };
  
  struct ltq_mtd {
  	struct resource *res;
  	struct mtd_info *mtd;
  	struct map_info *map;
  };

  static const char ltq_map_name[] = "ltq_nor";

  
  static map_word
  ltq_read16(struct map_info *map, unsigned long adr)
  {
  	unsigned long flags;
  	map_word temp;
  
  	if (map->map_priv_1 == LTQ_NOR_PROBING)
  		adr ^= 2;
  	spin_lock_irqsave(&ebu_lock, flags);
  	temp.x[0] = *(u16 *)(map->virt + adr);
  	spin_unlock_irqrestore(&ebu_lock, flags);
  	return temp;
  }
  
  static void
  ltq_write16(struct map_info *map, map_word d, unsigned long adr)
  {
  	unsigned long flags;
  
  	if (map->map_priv_1 == LTQ_NOR_PROBING)
  		adr ^= 2;
  	spin_lock_irqsave(&ebu_lock, flags);
  	*(u16 *)(map->virt + adr) = d.x[0];
  	spin_unlock_irqrestore(&ebu_lock, flags);
  }
  
  /*
   * The following 2 functions copy data between iomem and a cached memory
   * section. As memcpy() makes use of pre-fetching we cannot use it here.
   * The normal alternative of using memcpy_{to,from}io also makes use of
   * memcpy() on MIPS so it is not applicable either. We are therefore stuck
   * with having to use our own loop.
   */
  static void
  ltq_copy_from(struct map_info *map, void *to,
  	unsigned long from, ssize_t len)
  {
  	unsigned char *f = (unsigned char *)map->virt + from;
  	unsigned char *t = (unsigned char *)to;
  	unsigned long flags;
  
  	spin_lock_irqsave(&ebu_lock, flags);
  	while (len--)
  		*t++ = *f++;
  	spin_unlock_irqrestore(&ebu_lock, flags);
  }
  
  static void
  ltq_copy_to(struct map_info *map, unsigned long to,
  	const void *from, ssize_t len)
  {
  	unsigned char *f = (unsigned char *)from;
  	unsigned char *t = (unsigned char *)map->virt + to;
  	unsigned long flags;
  
  	spin_lock_irqsave(&ebu_lock, flags);
  	while (len--)
  		*t++ = *f++;
  	spin_unlock_irqrestore(&ebu_lock, flags);
  }

  static int

  ltq_mtd_probe(struct platform_device *pdev)
  {

  	struct ltq_mtd *ltq_mtd;

  	struct cfi_private *cfi;
  	int err;

  	if (of_machine_is_compatible("lantiq,falcon") &&
  			(ltq_boot_select() != BS_FLASH)) {
  		dev_err(&pdev->dev, "invalid bootstrap options
  ");
  		return -ENODEV;
  	}

  	ltq_mtd = devm_kzalloc(&pdev->dev, sizeof(struct ltq_mtd), GFP_KERNEL);
  	if (!ltq_mtd)
  		return -ENOMEM;

  	platform_set_drvdata(pdev, ltq_mtd);
  
  	ltq_mtd->res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	if (!ltq_mtd->res) {

  		dev_err(&pdev->dev, "failed to get memory resource
  ");

  		return -ENOENT;

  	}

  	ltq_mtd->map = devm_kzalloc(&pdev->dev, sizeof(struct map_info),
  				    GFP_KERNEL);
  	if (!ltq_mtd->map)
  		return -ENOMEM;

  	ltq_mtd->map->phys = ltq_mtd->res->start;
  	ltq_mtd->map->size = resource_size(ltq_mtd->res);

  	ltq_mtd->map->virt = devm_ioremap_resource(&pdev->dev, ltq_mtd->res);

  	if (IS_ERR(ltq_mtd->map->virt))
  		return PTR_ERR(ltq_mtd->map->virt);

  
  	ltq_mtd->map->name = ltq_map_name;
  	ltq_mtd->map->bankwidth = 2;
  	ltq_mtd->map->read = ltq_read16;
  	ltq_mtd->map->write = ltq_write16;
  	ltq_mtd->map->copy_from = ltq_copy_from;
  	ltq_mtd->map->copy_to = ltq_copy_to;
  
  	ltq_mtd->map->map_priv_1 = LTQ_NOR_PROBING;
  	ltq_mtd->mtd = do_map_probe("cfi_probe", ltq_mtd->map);
  	ltq_mtd->map->map_priv_1 = LTQ_NOR_NORMAL;
  
  	if (!ltq_mtd->mtd) {
  		dev_err(&pdev->dev, "probing failed
  ");

  		return -ENXIO;

  	}

  	ltq_mtd->mtd->dev.parent = &pdev->dev;

  	mtd_set_of_node(ltq_mtd->mtd, pdev->dev.of_node);

  
  	cfi = ltq_mtd->map->fldrv_priv;
  	cfi->addr_unlock1 ^= 1;
  	cfi->addr_unlock2 ^= 1;

  	err = mtd_device_register(ltq_mtd->mtd, NULL, 0);

  	if (err) {
  		dev_err(&pdev->dev, "failed to add partitions
  ");
  		goto err_destroy;
  	}
  
  	return 0;
  
  err_destroy:
  	map_destroy(ltq_mtd->mtd);

  	return err;
  }

  static int

  ltq_mtd_remove(struct platform_device *pdev)
  {
  	struct ltq_mtd *ltq_mtd = platform_get_drvdata(pdev);

  	if (ltq_mtd && ltq_mtd->mtd) {
  		mtd_device_unregister(ltq_mtd->mtd);
  		map_destroy(ltq_mtd->mtd);

  	}
  	return 0;
  }

  static const struct of_device_id ltq_mtd_match[] = {
  	{ .compatible = "lantiq,nor" },
  	{},
  };
  MODULE_DEVICE_TABLE(of, ltq_mtd_match);

  static struct platform_driver ltq_mtd_driver = {

  	.probe = ltq_mtd_probe,

  	.remove = ltq_mtd_remove,

  	.driver = {

  		.name = "ltq-nor",

  		.of_match_table = ltq_mtd_match,

  	},
  };

  module_platform_driver(ltq_mtd_driver);

  
  MODULE_LICENSE("GPL");

  MODULE_AUTHOR("John Crispin <john@phrozen.org>");

  MODULE_DESCRIPTION("Lantiq SoC NOR");