// SPDX-License-Identifier: GPL-2.0
//
// Register map access API - debugfs
//
// Copyright 2011 Wolfson Microelectronics plc
//
// Author: Mark Brown <broonie@opensource.wolfsonmicro.com>

#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/debugfs.h>
#include <linux/uaccess.h>
#include <linux/device.h>
#include <linux/list.h>

#include "internal.h"

struct regmap_debugfs_node {
        struct regmap *map;
        const char *name;
        struct list_head link;
};

static unsigned int dummy_index;
static struct dentry *regmap_debugfs_root;
static LIST_HEAD(regmap_debugfs_early_list);
static DEFINE_MUTEX(regmap_debugfs_early_lock);

/* Calculate the length of a fixed format  */
static size_t regmap_calc_reg_len(int max_val)
{
        return snprintf(NULL, 0, "%x", max_val);
}

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;
        const char *name = "nodev";
        int ret;
        char *buf;

        buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
        if (!buf)
                return -ENOMEM;

        if (map->dev && map->dev->driver)
                name = map->dev->driver->name;

        ret = snprintf(buf, PAGE_SIZE, "%s\n", 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);
        }
}

static bool regmap_printable(struct regmap *map, unsigned int reg)
{
        if (regmap_precious(map, reg))
                return false;

        if (!regmap_readable(map, reg) && !regmap_cached(map, reg))
                return false;

        return true;
}

/*
 * 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;

        /* Suppress the cache if we're using a subrange */
        if (base)
                return base;

        /*
         * 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_printable(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),
                map->debugfs_val_len = 2 * map->format.val_bytes;
                map->debugfs_tot_len = map->debugfs_reg_len +
                        map->debugfs_val_len + 3;      /* : \n */
        }
}

static int regmap_next_readable_reg(struct regmap *map, int reg)
{
        struct regmap_debugfs_off_cache *c;
        int ret = -EINVAL;

        if (regmap_printable(map, reg + map->reg_stride)) {
                ret = reg + map->reg_stride;
        } else {
                mutex_lock(&map->cache_lock);
                list_for_each_entry(c, &map->debugfs_off_cache, list) {
                        if (reg > c->max_reg)
                                continue;
                        if (reg < c->base_reg) {
                                ret = c->base_reg;
                                break;
                        }
                }
                mutex_unlock(&map->cache_lock);
        }
        return ret;
}

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 >= 0 && i <= to;
             i = regmap_next_readable_reg(map, i)) {

                /* 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);
}

#undef REGMAP_ALLOW_WRITE_DEBUGFS
#ifdef 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 (kstrtoul(start, 16, &value))
                return -EINVAL;

        /* Userspace has been fiddling around behind the kernel's back */
        add_taint(TAINT_USER, LOCKDEP_STILL_OK);

        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;
        unsigned entry_len;

        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) {
                entry_len = snprintf(entry, PAGE_SIZE, "%x-%x\n",
                                     c->base_reg, c->max_reg);
                if (p >= *ppos) {
                        if (buf_pos + entry_len > count)
                                break;
                        memcpy(buf + buf_pos, entry, entry_len);
                        buf_pos += entry_len;
                }
                p += entry_len;
        }
        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 int regmap_access_show(struct seq_file *s, void *ignored)
{
        struct regmap *map = s->private;
        int i, reg_len;

        reg_len = regmap_calc_reg_len(map->max_register);

        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;

                /* Format the register */
                seq_printf(s, "%.*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');
        }

        return 0;
}

DEFINE_SHOW_ATTRIBUTE(regmap_access);

static ssize_t regmap_cache_only_write_file(struct file *file,
                                            const char __user *user_buf,
                                            size_t count, loff_t *ppos)
{
        struct regmap *map = container_of(file->private_data,
                                          struct regmap, cache_only);
        ssize_t result;
        bool was_enabled, require_sync = false;
        int err;

        map->lock(map->lock_arg);

        was_enabled = map->cache_only;

        result = debugfs_write_file_bool(file, user_buf, count, ppos);
        if (result < 0) {
                map->unlock(map->lock_arg);
                return result;
        }

        if (map->cache_only && !was_enabled) {
                dev_warn(map->dev, "debugfs cache_only=Y forced\n");
                add_taint(TAINT_USER, LOCKDEP_STILL_OK);
        } else if (!map->cache_only && was_enabled) {
                dev_warn(map->dev, "debugfs cache_only=N forced: syncing cache\n");
                require_sync = true;
        }

        map->unlock(map->lock_arg);

        if (require_sync) {
                err = regcache_sync(map);
                if (err)
                        dev_err(map->dev, "Failed to sync cache %d\n", err);
        }

        return result;
}

static const struct file_operations regmap_cache_only_fops = {
        .open = simple_open,
        .read = debugfs_read_file_bool,
        .write = regmap_cache_only_write_file,
};

static ssize_t regmap_cache_bypass_write_file(struct file *file,
                                              const char __user *user_buf,
                                              size_t count, loff_t *ppos)
{
        struct regmap *map = container_of(file->private_data,
                                          struct regmap, cache_bypass);
        ssize_t result;
        bool was_enabled;

        map->lock(map->lock_arg);

        was_enabled = map->cache_bypass;

        result = debugfs_write_file_bool(file, user_buf, count, ppos);
        if (result < 0)
                goto out;

        if (map->cache_bypass && !was_enabled) {
                dev_warn(map->dev, "debugfs cache_bypass=Y forced\n");
                add_taint(TAINT_USER, LOCKDEP_STILL_OK);
        } else if (!map->cache_bypass && was_enabled) {
                dev_warn(map->dev, "debugfs cache_bypass=N forced\n");
        }

out:
        map->unlock(map->lock_arg);

        return result;
}

static const struct file_operations regmap_cache_bypass_fops = {
        .open = simple_open,
        .read = debugfs_read_file_bool,
        .write = regmap_cache_bypass_write_file,
};

void regmap_debugfs_init(struct regmap *map, const char *name)
{
        struct rb_node *next;
        struct regmap_range_node *range_node;
        const char *devname = "dummy";

        /*
         * Userspace can initiate reads from the hardware over debugfs.
         * Normally internal regmap structures and buffers are protected with
         * a mutex or a spinlock, but if the regmap owner decided to disable
         * all locking mechanisms, this is no longer the case. For safety:
         * don't create the debugfs entries if locking is disabled.
         */
        if (map->debugfs_disable) {
                dev_dbg(map->dev, "regmap locking disabled - not creating debugfs entries\n");
                return;
        }

        /* If we don't have the debugfs root yet, postpone init */
        if (!regmap_debugfs_root) {
                struct regmap_debugfs_node *node;
                node = kzalloc(sizeof(*node), GFP_KERNEL);
                if (!node)
                        return;
                node->map = map;
                node->name = name;
                mutex_lock(&regmap_debugfs_early_lock);
                list_add(&node->link, &regmap_debugfs_early_list);
                mutex_unlock(&regmap_debugfs_early_lock);
                return;
        }

        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;
        }

        if (!strcmp(name, "dummy")) {
                kfree(map->debugfs_name);

                map->debugfs_name = kasprintf(GFP_KERNEL, "dummy%d",
                                                dummy_index);
                name = map->debugfs_name;
                dummy_index++;
        }

        map->debugfs = debugfs_create_dir(name, regmap_debugfs_root);
        if (!map->debugfs) {
                dev_warn(map->dev,
                         "Failed to create %s debugfs directory\n", name);

                kfree(map->debugfs_name);
                map->debugfs_name = NULL;
                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 || regmap_readable(map, 0)) {
                umode_t registers_mode;

#if defined(REGMAP_ALLOW_WRITE_DEBUGFS)
                registers_mode = 0600;
#else
                registers_mode = 0400;
#endif

                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_file("cache_only", 0600, map->debugfs,
                                    &map->cache_only, &regmap_cache_only_fops);
                debugfs_create_bool("cache_dirty", 0400, map->debugfs,
                                    &map->cache_dirty);
                debugfs_create_file("cache_bypass", 0600, map->debugfs,
                                    &map->cache_bypass,
                                    &regmap_cache_bypass_fops);
        }

        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);
        }

        if (map->cache_ops && map->cache_ops->debugfs_init)
                map->cache_ops->debugfs_init(map);
}

void regmap_debugfs_exit(struct regmap *map)
{
        if (map->debugfs) {
                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);
        } else {
                struct regmap_debugfs_node *node, *tmp;

                mutex_lock(&regmap_debugfs_early_lock);
                list_for_each_entry_safe(node, tmp, &regmap_debugfs_early_list,
                                         link) {
                        if (node->map == map) {
                                list_del(&node->link);
                                kfree(node);
                        }
                }
                mutex_unlock(&regmap_debugfs_early_lock);
        }
}

void regmap_debugfs_initcall(void)
{
        struct regmap_debugfs_node *node, *tmp;

        regmap_debugfs_root = debugfs_create_dir("regmap", NULL);
        if (!regmap_debugfs_root) {
                pr_warn("regmap: Failed to create debugfs root\n");
                return;
        }

        mutex_lock(&regmap_debugfs_early_lock);
        list_for_each_entry_safe(node, tmp, &regmap_debugfs_early_list, link) {
                regmap_debugfs_init(node->map, node->name);
                list_del(&node->link);
                kfree(node);
        }
        mutex_unlock(&regmap_debugfs_early_lock);
}