text: /*
   * Register map access API - debugfs
   *
   * Copyright 2011 Wolfson Microelectronics plc
   *
   * Author: Mark Brown <broonie@opensource.wolfsonmicro.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.
   */
  
  #include <linux/slab.h>
  #include <linux/mutex.h>
  #include <linux/debugfs.h>
  #include <linux/uaccess.h>
  #include <linux/device.h>
  
  #include "internal.h"
  
  static struct dentry *regmap_debugfs_root;
  
  /* Calculate the length of a fixed format  */
  static size_t regmap_calc_reg_len(int max_val, char *buf, size_t buf_size)
  {
  	snprintf(buf, buf_size, "%x", max_val);
  	return strlen(buf);
  }
  
  static ssize_t regmap_name_read_file(struct file *file,
  				     char __user *user_buf, size_t count,
  				     loff_t *ppos)
  {
  	struct regmap *map = file->private_data;
  	int ret;
  	char *buf;
  
  	buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
  	if (!buf)
  		return -ENOMEM;
  
  	ret = snprintf(buf, PAGE_SIZE, "%s\n", map->dev->driver->name);
  	if (ret < 0) {
  		kfree(buf);
  		return ret;
  	}
  
  	ret = simple_read_from_buffer(user_buf, count, ppos, buf, ret);
  	kfree(buf);
  	return ret;
  }
  
  static const struct file_operations regmap_name_fops = {
  	.open = simple_open,
  	.read = regmap_name_read_file,
  	.llseek = default_llseek,
  };
  
  static void regmap_debugfs_free_dump_cache(struct regmap *map)
  {
  	struct regmap_debugfs_off_cache *c;
  
  	while (!list_empty(&map->debugfs_off_cache)) {
  		c = list_first_entry(&map->debugfs_off_cache,
  				     struct regmap_debugfs_off_cache,
  				     list);
  		list_del(&c->list);
  		kfree(c);
  	}
  }
  
  /*
   * Work out where the start offset maps into register numbers, bearing
   * in mind that we suppress hidden registers.
   */
  static unsigned int regmap_debugfs_get_dump_start(struct regmap *map,
  						  unsigned int base,
  						  loff_t from,
  						  loff_t *pos)
  {
  	struct regmap_debugfs_off_cache *c = NULL;
  	loff_t p = 0;
  	unsigned int i, ret;
  	unsigned int fpos_offset;
  	unsigned int reg_offset;
  
  	/*
  	 * If we don't have a cache build one so we don't have to do a
  	 * linear scan each time.
  	 */
  	mutex_lock(&map->cache_lock);
  	i = base;
  	if (list_empty(&map->debugfs_off_cache)) {
  		for (; i <= map->max_register; i += map->reg_stride) {
  			/* Skip unprinted registers, closing off cache entry */
  			if (!regmap_readable(map, i) ||
  			    regmap_precious(map, i)) {
  				if (c) {
  					c->max = p - 1;
  					c->max_reg = i - map->reg_stride;
  					list_add_tail(&c->list,
  						      &map->debugfs_off_cache);
  					c = NULL;
  				}
  
  				continue;
  			}
  
  			/* No cache entry?  Start a new one */
  			if (!c) {
  				c = kzalloc(sizeof(*c), GFP_KERNEL);
  				if (!c) {
  					regmap_debugfs_free_dump_cache(map);
  					mutex_unlock(&map->cache_lock);
  					return base;
  				}
  				c->min = p;
  				c->base_reg = i;
  			}
  
  			p += map->debugfs_tot_len;
  		}
  	}
  
  	/* Close the last entry off if we didn't scan beyond it */
  	if (c) {
  		c->max = p - 1;
  		c->max_reg = i - map->reg_stride;
  		list_add_tail(&c->list,
  			      &map->debugfs_off_cache);
  	}
  
  	/*
  	 * This should never happen; we return above if we fail to
  	 * allocate and we should never be in this code if there are
  	 * no registers at all.
  	 */
  	WARN_ON(list_empty(&map->debugfs_off_cache));
  	ret = base;
  
  	/* Find the relevant block:offset */
  	list_for_each_entry(c, &map->debugfs_off_cache, list) {
  		if (from >= c->min && from <= c->max) {
  			fpos_offset = from - c->min;
  			reg_offset = fpos_offset / map->debugfs_tot_len;
  			*pos = c->min + (reg_offset * map->debugfs_tot_len);
  			mutex_unlock(&map->cache_lock);
  			return c->base_reg + (reg_offset * map->reg_stride);
  		}
  
  		*pos = c->max;
  		ret = c->max_reg;
  	}
  	mutex_unlock(&map->cache_lock);
  
  	return ret;
  }
  
  static inline void regmap_calc_tot_len(struct regmap *map,
  				       void *buf, size_t count)
  {
  	/* Calculate the length of a fixed format  */
  	if (!map->debugfs_tot_len) {
  		map->debugfs_reg_len = regmap_calc_reg_len(map->max_register,
  							   buf, count);
  		map->debugfs_val_len = 2 * map->format.val_bytes;
  		map->debugfs_tot_len = map->debugfs_reg_len +
  			map->debugfs_val_len + 3;      /* : \n */
  	}
  }
  
  static ssize_t regmap_read_debugfs(struct regmap *map, unsigned int from,
  				   unsigned int to, char __user *user_buf,
  				   size_t count, loff_t *ppos)
  {
  	size_t buf_pos = 0;
  	loff_t p = *ppos;
  	ssize_t ret;
  	int i;
  	char *buf;
  	unsigned int val, start_reg;
  
  	if (*ppos < 0 || !count)
  		return -EINVAL;
  
  	buf = kmalloc(count, GFP_KERNEL);
  	if (!buf)
  		return -ENOMEM;
  
  	regmap_calc_tot_len(map, buf, count);
  
  	/* Work out which register we're starting at */
  	start_reg = regmap_debugfs_get_dump_start(map, from, *ppos, &p);
  
  	for (i = start_reg; i <= to; i += map->reg_stride) {
  		if (!regmap_readable(map, i))
  			continue;
  
  		if (regmap_precious(map, i))
  			continue;
  
  		/* If we're in the region the user is trying to read */
  		if (p >= *ppos) {
  			/* ...but not beyond it */
  			if (buf_pos + map->debugfs_tot_len > count)
  				break;
  
  			/* Format the register */
  			snprintf(buf + buf_pos, count - buf_pos, "%.*x: ",
  				 map->debugfs_reg_len, i - from);
  			buf_pos += map->debugfs_reg_len + 2;
  
  			/* Format the value, write all X if we can't read */
  			ret = regmap_read(map, i, &val);
  			if (ret == 0)
  				snprintf(buf + buf_pos, count - buf_pos,
  					 "%.*x", map->debugfs_val_len, val);
  			else
  				memset(buf + buf_pos, 'X',
  				       map->debugfs_val_len);
  			buf_pos += 2 * map->format.val_bytes;
  
  			buf[buf_pos++] = '\n';
  		}
  		p += map->debugfs_tot_len;
  	}
  
  	ret = buf_pos;
  
  	if (copy_to_user(user_buf, buf, buf_pos)) {
  		ret = -EFAULT;
  		goto out;
  	}
  
  	*ppos += buf_pos;
  
  out:
  	kfree(buf);
  	return ret;
  }
  
  static ssize_t regmap_map_read_file(struct file *file, char __user *user_buf,
  				    size_t count, loff_t *ppos)
  {
  	struct regmap *map = file->private_data;
  
  	return regmap_read_debugfs(map, 0, map->max_register, user_buf,
  				   count, ppos);
  }
  
  #if IS_ENABLED(CONFIG_REGMAP_ALLOW_WRITE_DEBUGFS)
  /*
   * This can be dangerous especially when we have clients such as
   * PMICs, therefore don't provide any real compile time configuration option
   * for this feature, people who want to use this will need to modify
   * the source code directly.
   */
  static ssize_t regmap_map_write_file(struct file *file,
  				     const char __user *user_buf,
  				     size_t count, loff_t *ppos)
  {
  	char buf[32];
  	size_t buf_size;
  	char *start = buf;
  	unsigned long reg, value;
  	struct regmap *map = file->private_data;
  	int ret;
  
  	buf_size = min(count, (sizeof(buf)-1));
  	if (copy_from_user(buf, user_buf, buf_size))
  		return -EFAULT;
  	buf[buf_size] = 0;
  
  	while (*start == ' ')
  		start++;
  	reg = simple_strtoul(start, &start, 16);
  	while (*start == ' ')
  		start++;
  	if (strict_strtoul(start, 16, &value))
  		return -EINVAL;
  
  	/* Userspace has been fiddling around behind the kernel's back */
  	add_taint(TAINT_USER, LOCKDEP_NOW_UNRELIABLE);
  
  	ret = regmap_write(map, reg, value);
  	if (ret < 0)
  		return ret;
  	return buf_size;
  }
  #else
  #define regmap_map_write_file NULL
  #endif
  
  static const struct file_operations regmap_map_fops = {
  	.open = simple_open,
  	.read = regmap_map_read_file,
  	.write = regmap_map_write_file,
  	.llseek = default_llseek,
  };
  
  static ssize_t regmap_range_read_file(struct file *file, char __user *user_buf,
  				      size_t count, loff_t *ppos)
  {
  	struct regmap_range_node *range = file->private_data;
  	struct regmap *map = range->map;
  
  	return regmap_read_debugfs(map, range->range_min, range->range_max,
  				   user_buf, count, ppos);
  }
  
  static const struct file_operations regmap_range_fops = {
  	.open = simple_open,
  	.read = regmap_range_read_file,
  	.llseek = default_llseek,
  };
  
  static ssize_t regmap_reg_ranges_read_file(struct file *file,
  					   char __user *user_buf, size_t count,
  					   loff_t *ppos)
  {
  	struct regmap *map = file->private_data;
  	struct regmap_debugfs_off_cache *c;
  	loff_t p = 0;
  	size_t buf_pos = 0;
  	char *buf;
  	char *entry;
  	int ret;
  
  	if (*ppos < 0 || !count)
  		return -EINVAL;
  
  	buf = kmalloc(count, GFP_KERNEL);
  	if (!buf)
  		return -ENOMEM;
  
  	entry = kmalloc(PAGE_SIZE, GFP_KERNEL);
  	if (!entry) {
  		kfree(buf);
  		return -ENOMEM;
  	}
  
  	/* While we are at it, build the register dump cache
  	 * now so the read() operation on the `registers' file
  	 * can benefit from using the cache.  We do not care
  	 * about the file position information that is contained
  	 * in the cache, just about the actual register blocks */
  	regmap_calc_tot_len(map, buf, count);
  	regmap_debugfs_get_dump_start(map, 0, *ppos, &p);
  
  	/* Reset file pointer as the fixed-format of the `registers'
  	 * file is not compatible with the `range' file */
  	p = 0;
  	mutex_lock(&map->cache_lock);
  	list_for_each_entry(c, &map->debugfs_off_cache, list) {
  		snprintf(entry, PAGE_SIZE, "%x-%x",
  			 c->base_reg, c->max_reg);
  		if (p >= *ppos) {
  			if (buf_pos + 1 + strlen(entry) > count)
  				break;
  			snprintf(buf + buf_pos, count - buf_pos,
  				 "%s", entry);
  			buf_pos += strlen(entry);
  			buf[buf_pos] = '\n';
  			buf_pos++;
  		}
  		p += strlen(entry) + 1;
  	}
  	mutex_unlock(&map->cache_lock);
  
  	kfree(entry);
  	ret = buf_pos;
  
  	if (copy_to_user(user_buf, buf, buf_pos)) {
  		ret = -EFAULT;
  		goto out_buf;
  	}
  
  	*ppos += buf_pos;
  out_buf:
  	kfree(buf);
  	return ret;
  }
  
  static const struct file_operations regmap_reg_ranges_fops = {
  	.open = simple_open,
  	.read = regmap_reg_ranges_read_file,
  	.llseek = default_llseek,
  };
  
  static ssize_t regmap_access_read_file(struct file *file,
  				       char __user *user_buf, size_t count,
  				       loff_t *ppos)
  {
  	int reg_len, tot_len;
  	size_t buf_pos = 0;
  	loff_t p = 0;
  	ssize_t ret;
  	int i;
  	struct regmap *map = file->private_data;
  	char *buf;
  
  	if (*ppos < 0 || !count)
  		return -EINVAL;
  
  	buf = kmalloc(count, GFP_KERNEL);
  	if (!buf)
  		return -ENOMEM;
  
  	/* Calculate the length of a fixed format  */
  	reg_len = regmap_calc_reg_len(map->max_register, buf, count);
  	tot_len = reg_len + 10; /* ': R W V P\n' */
  
  	for (i = 0; i <= map->max_register; i += map->reg_stride) {
  		/* Ignore registers which are neither readable nor writable */
  		if (!regmap_readable(map, i) && !regmap_writeable(map, i))
  			continue;
  
  		/* If we're in the region the user is trying to read */
  		if (p >= *ppos) {
  			/* ...but not beyond it */
  			if (buf_pos >= count - 1 - tot_len)
  				break;
  
  			/* Format the register */
  			snprintf(buf + buf_pos, count - buf_pos,
  				 "%.*x: %c %c %c %c\n",
  				 reg_len, i,
  				 regmap_readable(map, i) ? 'y' : 'n',
  				 regmap_writeable(map, i) ? 'y' : 'n',
  				 regmap_volatile(map, i) ? 'y' : 'n',
  				 regmap_precious(map, i) ? 'y' : 'n');
  
  			buf_pos += tot_len;
  		}
  		p += tot_len;
  	}
  
  	ret = buf_pos;
  
  	if (copy_to_user(user_buf, buf, buf_pos)) {
  		ret = -EFAULT;
  		goto out;
  	}
  
  	*ppos += buf_pos;
  
  out:
  	kfree(buf);
  	return ret;
  }
  
  static const struct file_operations regmap_access_fops = {
  	.open = simple_open,
  	.read = regmap_access_read_file,
  	.llseek = default_llseek,
  };
  
  void regmap_debugfs_init(struct regmap *map, const char *name)
  {
  	struct rb_node *next;
  	struct regmap_range_node *range_node;
  	const char *devname = "dummy";
  
  	INIT_LIST_HEAD(&map->debugfs_off_cache);
  	mutex_init(&map->cache_lock);
  
  	if (map->dev)
  		devname = dev_name(map->dev);
  
  	if (name) {
  		map->debugfs_name = kasprintf(GFP_KERNEL, "%s-%s",
  					      devname, name);
  		name = map->debugfs_name;
  	} else {
  		name = devname;
  	}
  
  	map->debugfs = debugfs_create_dir(name, regmap_debugfs_root);
  	if (!map->debugfs) {
  		dev_warn(map->dev, "Failed to create debugfs directory\n");
  		return;
  	}
  
  	debugfs_create_file("name", 0400, map->debugfs,
  			    map, &regmap_name_fops);
  
  	debugfs_create_file("range", 0400, map->debugfs,
  			    map, &regmap_reg_ranges_fops);
  
  	if (map->max_register) {
  		umode_t registers_mode;
  
  		if (IS_ENABLED(CONFIG_REGMAP_ALLOW_WRITE_DEBUGFS))
  			registers_mode = 0600;
  		else
  			registers_mode = 0400;
  
  		debugfs_create_file("registers", registers_mode, map->debugfs,
  				    map, &regmap_map_fops);
  		debugfs_create_file("access", 0400, map->debugfs,
  				    map, &regmap_access_fops);
  	}
  
  	if (map->cache_type) {
  		debugfs_create_bool("cache_only", 0400, map->debugfs,
  				    &map->cache_only);
  		debugfs_create_bool("cache_dirty", 0400, map->debugfs,
  				    &map->cache_dirty);
  		debugfs_create_bool("cache_bypass", 0400, map->debugfs,
  				    &map->cache_bypass);
  	}
  
  	next = rb_first(&map->range_tree);
  	while (next) {
  		range_node = rb_entry(next, struct regmap_range_node, node);
  
  		if (range_node->name)
  			debugfs_create_file(range_node->name, 0400,
  					    map->debugfs, range_node,
  					    &regmap_range_fops);
  
  		next = rb_next(&range_node->node);
  	}
  }
  
  void regmap_debugfs_exit(struct regmap *map)
  {
  	debugfs_remove_recursive(map->debugfs);
  	mutex_lock(&map->cache_lock);
  	regmap_debugfs_free_dump_cache(map);
  	mutex_unlock(&map->cache_lock);
  	kfree(map->debugfs_name);
  }
  
  void regmap_debugfs_initcall(void)
  {
  	regmap_debugfs_root = debugfs_create_dir("regmap", NULL);
  	if (!regmap_debugfs_root) {
  		pr_warn("regmap: Failed to create debugfs root\n");
  		return;
  	}
  }
  