file.c

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/*
 *  file.c - part of debugfs, a tiny little debug file system
 *
 *  Copyright (C) 2004 Greg Kroah-Hartman <[email protected]>
 *  Copyright (C) 2004 IBM Inc.
 *
 *  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.
 *
 *  debugfs is for people to use instead of /proc or /sys.
 *  See Documentation/DocBook/filesystems for more details.
 *
 */

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/seq_file.h>
#include <linux/pagemap.h>
#include <linux/namei.h>
#include <linux/debugfs.h>
#include <linux/io.h>
#include <linux/slab.h>

static ssize_t default_read_file(struct file *file, char __user *buf,
                 size_t count, loff_t *ppos)
{
    return 0;
}

static ssize_t default_write_file(struct file *file, const char __user *buf,
                   size_t count, loff_t *ppos)
{
    return count;
}

const struct file_operations debugfs_file_operations = {
    .read =     default_read_file,
    .write =    default_write_file,
    .open =     simple_open,
    .llseek =   noop_llseek,
};

static void *debugfs_follow_link(struct dentry *dentry, struct nameidata *nd)
{
    nd_set_link(nd, dentry->d_inode->i_private);
    return NULL;
}

const struct inode_operations debugfs_link_operations = {
    .readlink       = generic_readlink,
    .follow_link    = debugfs_follow_link,
};

static int debugfs_u8_set(void *data, u64 val)
{
    *(u8 *)data = val;
    return 0;
}
static int debugfs_u8_get(void *data, u64 *val)
{
    *val = *(u8 *)data;
    return 0;
}
DEFINE_SIMPLE_ATTRIBUTE(fops_u8, debugfs_u8_get, debugfs_u8_set, "%llu\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_u8_ro, debugfs_u8_get, NULL, "%llu\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_u8_wo, NULL, debugfs_u8_set, "%llu\n");

struct dentry *debugfs_create_u8(const char *name, umode_t mode,
                 struct dentry *parent, u8 *value)
{
    /* if there are no write bits set, make read only */
    if (!(mode & S_IWUGO))
        return debugfs_create_file(name, mode, parent, value, &fops_u8_ro);
    /* if there are no read bits set, make write only */
    if (!(mode & S_IRUGO))
        return debugfs_create_file(name, mode, parent, value, &fops_u8_wo);

    return debugfs_create_file(name, mode, parent, value, &fops_u8);
}
EXPORT_SYMBOL_GPL(debugfs_create_u8);

static int debugfs_u16_set(void *data, u64 val)
{
    *(u16 *)data = val;
    return 0;
}
static int debugfs_u16_get(void *data, u64 *val)
{
    *val = *(u16 *)data;
    return 0;
}
DEFINE_SIMPLE_ATTRIBUTE(fops_u16, debugfs_u16_get, debugfs_u16_set, "%llu\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_u16_ro, debugfs_u16_get, NULL, "%llu\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_u16_wo, NULL, debugfs_u16_set, "%llu\n");

struct dentry *debugfs_create_u16(const char *name, umode_t mode,
                  struct dentry *parent, u16 *value)
{
    /* if there are no write bits set, make read only */
    if (!(mode & S_IWUGO))
        return debugfs_create_file(name, mode, parent, value, &fops_u16_ro);
    /* if there are no read bits set, make write only */
    if (!(mode & S_IRUGO))
        return debugfs_create_file(name, mode, parent, value, &fops_u16_wo);

    return debugfs_create_file(name, mode, parent, value, &fops_u16);
}
EXPORT_SYMBOL_GPL(debugfs_create_u16);

static int debugfs_u32_set(void *data, u64 val)
{
    *(u32 *)data = val;
    return 0;
}
static int debugfs_u32_get(void *data, u64 *val)
{
    *val = *(u32 *)data;
    return 0;
}
DEFINE_SIMPLE_ATTRIBUTE(fops_u32, debugfs_u32_get, debugfs_u32_set, "%llu\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_u32_ro, debugfs_u32_get, NULL, "%llu\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_u32_wo, NULL, debugfs_u32_set, "%llu\n");

struct dentry *debugfs_create_u32(const char *name, umode_t mode,
                 struct dentry *parent, u32 *value)
{
    /* if there are no write bits set, make read only */
    if (!(mode & S_IWUGO))
        return debugfs_create_file(name, mode, parent, value, &fops_u32_ro);
    /* if there are no read bits set, make write only */
    if (!(mode & S_IRUGO))
        return debugfs_create_file(name, mode, parent, value, &fops_u32_wo);

    return debugfs_create_file(name, mode, parent, value, &fops_u32);
}
EXPORT_SYMBOL_GPL(debugfs_create_u32);

static int debugfs_u64_set(void *data, u64 val)
{
    *(u64 *)data = val;
    return 0;
}

static int debugfs_u64_get(void *data, u64 *val)
{
    *val = *(u64 *)data;
    return 0;
}
DEFINE_SIMPLE_ATTRIBUTE(fops_u64, debugfs_u64_get, debugfs_u64_set, "%llu\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_u64_ro, debugfs_u64_get, NULL, "%llu\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_u64_wo, NULL, debugfs_u64_set, "%llu\n");

struct dentry *debugfs_create_u64(const char *name, umode_t mode,
                 struct dentry *parent, u64 *value)
{
    /* if there are no write bits set, make read only */
    if (!(mode & S_IWUGO))
        return debugfs_create_file(name, mode, parent, value, &fops_u64_ro);
    /* if there are no read bits set, make write only */
    if (!(mode & S_IRUGO))
        return debugfs_create_file(name, mode, parent, value, &fops_u64_wo);

    return debugfs_create_file(name, mode, parent, value, &fops_u64);
}
EXPORT_SYMBOL_GPL(debugfs_create_u64);

DEFINE_SIMPLE_ATTRIBUTE(fops_x8, debugfs_u8_get, debugfs_u8_set, "0x%02llx\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_x8_ro, debugfs_u8_get, NULL, "0x%02llx\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_x8_wo, NULL, debugfs_u8_set, "0x%02llx\n");

DEFINE_SIMPLE_ATTRIBUTE(fops_x16, debugfs_u16_get, debugfs_u16_set, "0x%04llx\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_x16_ro, debugfs_u16_get, NULL, "0x%04llx\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_x16_wo, NULL, debugfs_u16_set, "0x%04llx\n");

DEFINE_SIMPLE_ATTRIBUTE(fops_x32, debugfs_u32_get, debugfs_u32_set, "0x%08llx\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_x32_ro, debugfs_u32_get, NULL, "0x%08llx\n");
DEFINE_SIMPLE_ATTRIBUTE(fops_x32_wo, NULL, debugfs_u32_set, "0x%08llx\n");

DEFINE_SIMPLE_ATTRIBUTE(fops_x64, debugfs_u64_get, debugfs_u64_set, "0x%016llx\n");

/*
 * debugfs_create_x{8,16,32,64} - create a debugfs file that is used to read and write an unsigned {8,16,32,64}-bit value
 *
 * These functions are exactly the same as the above functions (but use a hex
 * output for the decimal challenged). For details look at the above unsigned
 * decimal functions.
 */

struct dentry *debugfs_create_x8(const char *name, umode_t mode,
                 struct dentry *parent, u8 *value)
{
    /* if there are no write bits set, make read only */
    if (!(mode & S_IWUGO))
        return debugfs_create_file(name, mode, parent, value, &fops_x8_ro);
    /* if there are no read bits set, make write only */
    if (!(mode & S_IRUGO))
        return debugfs_create_file(name, mode, parent, value, &fops_x8_wo);

    return debugfs_create_file(name, mode, parent, value, &fops_x8);
}
EXPORT_SYMBOL_GPL(debugfs_create_x8);

struct dentry *debugfs_create_x16(const char *name, umode_t mode,
                 struct dentry *parent, u16 *value)
{
    /* if there are no write bits set, make read only */
    if (!(mode & S_IWUGO))
        return debugfs_create_file(name, mode, parent, value, &fops_x16_ro);
    /* if there are no read bits set, make write only */
    if (!(mode & S_IRUGO))
        return debugfs_create_file(name, mode, parent, value, &fops_x16_wo);

    return debugfs_create_file(name, mode, parent, value, &fops_x16);
}
EXPORT_SYMBOL_GPL(debugfs_create_x16);

struct dentry *debugfs_create_x32(const char *name, umode_t mode,
                 struct dentry *parent, u32 *value)
{
    /* if there are no write bits set, make read only */
    if (!(mode & S_IWUGO))
        return debugfs_create_file(name, mode, parent, value, &fops_x32_ro);
    /* if there are no read bits set, make write only */
    if (!(mode & S_IRUGO))
        return debugfs_create_file(name, mode, parent, value, &fops_x32_wo);

    return debugfs_create_file(name, mode, parent, value, &fops_x32);
}
EXPORT_SYMBOL_GPL(debugfs_create_x32);

struct dentry *debugfs_create_x64(const char *name, umode_t mode,
                 struct dentry *parent, u64 *value)
{
    return debugfs_create_file(name, mode, parent, value, &fops_x64);
}
EXPORT_SYMBOL_GPL(debugfs_create_x64);


static int debugfs_size_t_set(void *data, u64 val)
{
    *(size_t *)data = val;
    return 0;
}
static int debugfs_size_t_get(void *data, u64 *val)
{
    *val = *(size_t *)data;
    return 0;
}
DEFINE_SIMPLE_ATTRIBUTE(fops_size_t, debugfs_size_t_get, debugfs_size_t_set,
            "%llu\n");  /* %llu and %zu are more or less the same */

struct dentry *debugfs_create_size_t(const char *name, umode_t mode,
                     struct dentry *parent, size_t *value)
{
    return debugfs_create_file(name, mode, parent, value, &fops_size_t);
}
EXPORT_SYMBOL_GPL(debugfs_create_size_t);


static ssize_t read_file_bool(struct file *file, char __user *user_buf,
                  size_t count, loff_t *ppos)
{
    char buf[3];
    u32 *val = file->private_data;
    
    if (*val)
        buf[0] = 'Y';
    else
        buf[0] = 'N';
    buf[1] = '\n';
    buf[2] = 0x00;
    return simple_read_from_buffer(user_buf, count, ppos, buf, 2);
}

static ssize_t write_file_bool(struct file *file, const char __user *user_buf,
                   size_t count, loff_t *ppos)
{
    char buf[32];
    size_t buf_size;
    bool bv;
    u32 *val = file->private_data;

    buf_size = min(count, (sizeof(buf)-1));
    if (copy_from_user(buf, user_buf, buf_size))
        return -EFAULT;

    if (strtobool(buf, &bv) == 0)
        *val = bv;

    return count;
}

static const struct file_operations fops_bool = {
    .read =     read_file_bool,
    .write =    write_file_bool,
    .open =     simple_open,
    .llseek =   default_llseek,
};

struct dentry *debugfs_create_bool(const char *name, umode_t mode,
                   struct dentry *parent, u32 *value)
{
    return debugfs_create_file(name, mode, parent, value, &fops_bool);
}
EXPORT_SYMBOL_GPL(debugfs_create_bool);

static ssize_t read_file_blob(struct file *file, char __user *user_buf,
                  size_t count, loff_t *ppos)
{
    struct debugfs_blob_wrapper *blob = file->private_data;
    return simple_read_from_buffer(user_buf, count, ppos, blob->data,
            blob->size);
}

static const struct file_operations fops_blob = {
    .read =     read_file_blob,
    .open =     simple_open,
    .llseek =   default_llseek,
};

struct dentry *debugfs_create_blob(const char *name, umode_t mode,
                   struct dentry *parent,
                   struct debugfs_blob_wrapper *blob)
{
    return debugfs_create_file(name, mode, parent, blob, &fops_blob);
}
EXPORT_SYMBOL_GPL(debugfs_create_blob);

struct array_data {
    void *array;
    u32 elements;
};

static size_t u32_format_array(char *buf, size_t bufsize,
                   u32 *array, int array_size)
{
    size_t ret = 0;

    while (--array_size >= 0) {
        size_t len;
        char term = array_size ? ' ' : '\n';

        len = snprintf(buf, bufsize, "%u%c", *array++, term);
        ret += len;

        buf += len;
        bufsize -= len;
    }
    return ret;
}

static int u32_array_open(struct inode *inode, struct file *file)
{
    struct array_data *data = inode->i_private;
    int size, elements = data->elements;
    char *buf;

    /*
     * Max size:
     *  - 10 digits + ' '/'\n' = 11 bytes per number
     *  - terminating NUL character
     */
    size = elements*11;
    buf = kmalloc(size+1, GFP_KERNEL);
    if (!buf)
        return -ENOMEM;
    buf[size] = 0;

    file->private_data = buf;
    u32_format_array(buf, size, data->array, data->elements);

    return nonseekable_open(inode, file);
}

static ssize_t u32_array_read(struct file *file, char __user *buf, size_t len,
                  loff_t *ppos)
{
    size_t size = strlen(file->private_data);

    return simple_read_from_buffer(buf, len, ppos,
                    file->private_data, size);
}

static int u32_array_release(struct inode *inode, struct file *file)
{
    kfree(file->private_data);

    return 0;
}

static const struct file_operations u32_array_fops = {
    .owner   = THIS_MODULE,
    .open    = u32_array_open,
    .release = u32_array_release,
    .read    = u32_array_read,
    .llseek  = no_llseek,
};

struct dentry *debugfs_create_u32_array(const char *name, umode_t mode,
                        struct dentry *parent,
                        u32 *array, u32 elements)
{
    struct array_data *data = kmalloc(sizeof(*data), GFP_KERNEL);

    if (data == NULL)
        return NULL;

    data->array = array;
    data->elements = elements;

    return debugfs_create_file(name, mode, parent, data, &u32_array_fops);
}
EXPORT_SYMBOL_GPL(debugfs_create_u32_array);

#ifdef CONFIG_HAS_IOMEM

/*
 * The regset32 stuff is used to print 32-bit registers using the
 * seq_file utilities. We offer printing a register set in an already-opened
 * sequential file or create a debugfs file that only prints a regset32.
 */

int debugfs_print_regs32(struct seq_file *s, const struct debugfs_reg32 *regs,
               int nregs, void __iomem *base, char *prefix)
{
    int i, ret = 0;

    for (i = 0; i < nregs; i++, regs++) {
        if (prefix)
            ret += seq_printf(s, "%s", prefix);
        ret += seq_printf(s, "%s = 0x%08x\n", regs->name,
                  readl(base + regs->offset));
    }
    return ret;
}
EXPORT_SYMBOL_GPL(debugfs_print_regs32);

static int debugfs_show_regset32(struct seq_file *s, void *data)
{
    struct debugfs_regset32 *regset = s->private;

    debugfs_print_regs32(s, regset->regs, regset->nregs, regset->base, "");
    return 0;
}

static int debugfs_open_regset32(struct inode *inode, struct file *file)
{
    return single_open(file, debugfs_show_regset32, inode->i_private);
}

static const struct file_operations fops_regset32 = {
    .open =     debugfs_open_regset32,
    .read =     seq_read,
    .llseek =   seq_lseek,
    .release =  single_release,
};

struct dentry *debugfs_create_regset32(const char *name, umode_t mode,
                       struct dentry *parent,
                       struct debugfs_regset32 *regset)
{
    return debugfs_create_file(name, mode, parent, regset, &fops_regset32);
}
EXPORT_SYMBOL_GPL(debugfs_create_regset32);

#endif /* CONFIG_HAS_IOMEM */