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![Cristian Birsan](/assets/img/avatar_default.png)
Add support for dumping write only device registers in debugfs. This is useful for audio codecs that have write only registers (like WM8731). The logic that decides if a value can be printed is moved to regmap_printable() function to allow for easier future updates. Signed-off-by: Cristian Birsan <cristian.birsan@microchip.com> Signed-off-by: Mark Brown <broonie@kernel.org>
653 lines
16 KiB
C
653 lines
16 KiB
C
/*
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* Register map access API - debugfs
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*
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* Copyright 2011 Wolfson Microelectronics plc
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*
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* Author: Mark Brown <broonie@opensource.wolfsonmicro.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/slab.h>
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#include <linux/mutex.h>
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#include <linux/debugfs.h>
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#include <linux/uaccess.h>
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#include <linux/device.h>
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#include <linux/list.h>
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#include "internal.h"
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struct regmap_debugfs_node {
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struct regmap *map;
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const char *name;
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struct list_head link;
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};
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static struct dentry *regmap_debugfs_root;
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static LIST_HEAD(regmap_debugfs_early_list);
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static DEFINE_MUTEX(regmap_debugfs_early_lock);
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/* Calculate the length of a fixed format */
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static size_t regmap_calc_reg_len(int max_val)
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{
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return snprintf(NULL, 0, "%x", max_val);
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}
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static ssize_t regmap_name_read_file(struct file *file,
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char __user *user_buf, size_t count,
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loff_t *ppos)
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{
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struct regmap *map = file->private_data;
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int ret;
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char *buf;
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buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
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if (!buf)
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return -ENOMEM;
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ret = snprintf(buf, PAGE_SIZE, "%s\n", map->dev->driver->name);
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if (ret < 0) {
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kfree(buf);
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return ret;
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}
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ret = simple_read_from_buffer(user_buf, count, ppos, buf, ret);
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kfree(buf);
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return ret;
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}
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static const struct file_operations regmap_name_fops = {
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.open = simple_open,
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.read = regmap_name_read_file,
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.llseek = default_llseek,
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};
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static void regmap_debugfs_free_dump_cache(struct regmap *map)
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{
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struct regmap_debugfs_off_cache *c;
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while (!list_empty(&map->debugfs_off_cache)) {
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c = list_first_entry(&map->debugfs_off_cache,
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struct regmap_debugfs_off_cache,
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list);
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list_del(&c->list);
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kfree(c);
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}
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}
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static bool regmap_printable(struct regmap *map, unsigned int reg)
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{
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if (regmap_precious(map, reg))
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return false;
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if (!regmap_readable(map, reg) && !regmap_cached(map, reg))
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return false;
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return true;
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}
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/*
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* Work out where the start offset maps into register numbers, bearing
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* in mind that we suppress hidden registers.
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*/
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static unsigned int regmap_debugfs_get_dump_start(struct regmap *map,
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unsigned int base,
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loff_t from,
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loff_t *pos)
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{
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struct regmap_debugfs_off_cache *c = NULL;
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loff_t p = 0;
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unsigned int i, ret;
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unsigned int fpos_offset;
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unsigned int reg_offset;
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/* Suppress the cache if we're using a subrange */
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if (base)
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return base;
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/*
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* If we don't have a cache build one so we don't have to do a
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* linear scan each time.
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*/
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mutex_lock(&map->cache_lock);
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i = base;
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if (list_empty(&map->debugfs_off_cache)) {
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for (; i <= map->max_register; i += map->reg_stride) {
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/* Skip unprinted registers, closing off cache entry */
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if (!regmap_printable(map, i)) {
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if (c) {
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c->max = p - 1;
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c->max_reg = i - map->reg_stride;
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list_add_tail(&c->list,
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&map->debugfs_off_cache);
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c = NULL;
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}
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continue;
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}
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/* No cache entry? Start a new one */
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if (!c) {
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c = kzalloc(sizeof(*c), GFP_KERNEL);
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if (!c) {
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regmap_debugfs_free_dump_cache(map);
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mutex_unlock(&map->cache_lock);
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return base;
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}
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c->min = p;
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c->base_reg = i;
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}
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p += map->debugfs_tot_len;
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}
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}
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/* Close the last entry off if we didn't scan beyond it */
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if (c) {
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c->max = p - 1;
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c->max_reg = i - map->reg_stride;
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list_add_tail(&c->list,
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&map->debugfs_off_cache);
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}
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/*
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* This should never happen; we return above if we fail to
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* allocate and we should never be in this code if there are
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* no registers at all.
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*/
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WARN_ON(list_empty(&map->debugfs_off_cache));
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ret = base;
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/* Find the relevant block:offset */
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list_for_each_entry(c, &map->debugfs_off_cache, list) {
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if (from >= c->min && from <= c->max) {
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fpos_offset = from - c->min;
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reg_offset = fpos_offset / map->debugfs_tot_len;
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*pos = c->min + (reg_offset * map->debugfs_tot_len);
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mutex_unlock(&map->cache_lock);
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return c->base_reg + (reg_offset * map->reg_stride);
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}
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*pos = c->max;
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ret = c->max_reg;
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}
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mutex_unlock(&map->cache_lock);
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return ret;
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}
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static inline void regmap_calc_tot_len(struct regmap *map,
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void *buf, size_t count)
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{
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/* Calculate the length of a fixed format */
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if (!map->debugfs_tot_len) {
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map->debugfs_reg_len = regmap_calc_reg_len(map->max_register),
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map->debugfs_val_len = 2 * map->format.val_bytes;
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map->debugfs_tot_len = map->debugfs_reg_len +
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map->debugfs_val_len + 3; /* : \n */
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}
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}
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static ssize_t regmap_read_debugfs(struct regmap *map, unsigned int from,
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unsigned int to, char __user *user_buf,
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size_t count, loff_t *ppos)
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{
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size_t buf_pos = 0;
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loff_t p = *ppos;
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ssize_t ret;
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int i;
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char *buf;
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unsigned int val, start_reg;
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if (*ppos < 0 || !count)
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return -EINVAL;
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buf = kmalloc(count, GFP_KERNEL);
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if (!buf)
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return -ENOMEM;
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regmap_calc_tot_len(map, buf, count);
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/* Work out which register we're starting at */
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start_reg = regmap_debugfs_get_dump_start(map, from, *ppos, &p);
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for (i = start_reg; i <= to; i += map->reg_stride) {
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if (!regmap_readable(map, i) && !regmap_cached(map, i))
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continue;
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if (regmap_precious(map, i))
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continue;
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/* If we're in the region the user is trying to read */
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if (p >= *ppos) {
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/* ...but not beyond it */
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if (buf_pos + map->debugfs_tot_len > count)
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break;
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/* Format the register */
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snprintf(buf + buf_pos, count - buf_pos, "%.*x: ",
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map->debugfs_reg_len, i - from);
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buf_pos += map->debugfs_reg_len + 2;
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/* Format the value, write all X if we can't read */
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ret = regmap_read(map, i, &val);
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if (ret == 0)
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snprintf(buf + buf_pos, count - buf_pos,
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"%.*x", map->debugfs_val_len, val);
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else
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memset(buf + buf_pos, 'X',
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map->debugfs_val_len);
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buf_pos += 2 * map->format.val_bytes;
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buf[buf_pos++] = '\n';
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}
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p += map->debugfs_tot_len;
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}
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ret = buf_pos;
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if (copy_to_user(user_buf, buf, buf_pos)) {
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ret = -EFAULT;
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goto out;
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}
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*ppos += buf_pos;
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out:
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kfree(buf);
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return ret;
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}
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static ssize_t regmap_map_read_file(struct file *file, char __user *user_buf,
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size_t count, loff_t *ppos)
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{
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struct regmap *map = file->private_data;
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return regmap_read_debugfs(map, 0, map->max_register, user_buf,
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count, ppos);
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}
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#undef REGMAP_ALLOW_WRITE_DEBUGFS
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#ifdef REGMAP_ALLOW_WRITE_DEBUGFS
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/*
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* This can be dangerous especially when we have clients such as
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* PMICs, therefore don't provide any real compile time configuration option
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* for this feature, people who want to use this will need to modify
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* the source code directly.
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*/
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static ssize_t regmap_map_write_file(struct file *file,
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const char __user *user_buf,
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size_t count, loff_t *ppos)
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{
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char buf[32];
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size_t buf_size;
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char *start = buf;
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unsigned long reg, value;
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struct regmap *map = file->private_data;
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int ret;
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buf_size = min(count, (sizeof(buf)-1));
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if (copy_from_user(buf, user_buf, buf_size))
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return -EFAULT;
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buf[buf_size] = 0;
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while (*start == ' ')
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start++;
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reg = simple_strtoul(start, &start, 16);
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while (*start == ' ')
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start++;
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if (kstrtoul(start, 16, &value))
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return -EINVAL;
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/* Userspace has been fiddling around behind the kernel's back */
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add_taint(TAINT_USER, LOCKDEP_STILL_OK);
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ret = regmap_write(map, reg, value);
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if (ret < 0)
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return ret;
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return buf_size;
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}
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#else
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#define regmap_map_write_file NULL
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#endif
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static const struct file_operations regmap_map_fops = {
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.open = simple_open,
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.read = regmap_map_read_file,
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.write = regmap_map_write_file,
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.llseek = default_llseek,
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};
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static ssize_t regmap_range_read_file(struct file *file, char __user *user_buf,
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size_t count, loff_t *ppos)
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{
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struct regmap_range_node *range = file->private_data;
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struct regmap *map = range->map;
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return regmap_read_debugfs(map, range->range_min, range->range_max,
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user_buf, count, ppos);
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}
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static const struct file_operations regmap_range_fops = {
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.open = simple_open,
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.read = regmap_range_read_file,
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.llseek = default_llseek,
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};
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static ssize_t regmap_reg_ranges_read_file(struct file *file,
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char __user *user_buf, size_t count,
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loff_t *ppos)
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{
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struct regmap *map = file->private_data;
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struct regmap_debugfs_off_cache *c;
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loff_t p = 0;
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size_t buf_pos = 0;
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char *buf;
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char *entry;
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int ret;
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unsigned entry_len;
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if (*ppos < 0 || !count)
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return -EINVAL;
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buf = kmalloc(count, GFP_KERNEL);
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if (!buf)
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return -ENOMEM;
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entry = kmalloc(PAGE_SIZE, GFP_KERNEL);
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if (!entry) {
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kfree(buf);
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return -ENOMEM;
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}
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/* While we are at it, build the register dump cache
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* now so the read() operation on the `registers' file
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* can benefit from using the cache. We do not care
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* about the file position information that is contained
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* in the cache, just about the actual register blocks */
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regmap_calc_tot_len(map, buf, count);
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regmap_debugfs_get_dump_start(map, 0, *ppos, &p);
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/* Reset file pointer as the fixed-format of the `registers'
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* file is not compatible with the `range' file */
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p = 0;
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mutex_lock(&map->cache_lock);
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list_for_each_entry(c, &map->debugfs_off_cache, list) {
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entry_len = snprintf(entry, PAGE_SIZE, "%x-%x\n",
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c->base_reg, c->max_reg);
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if (p >= *ppos) {
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if (buf_pos + entry_len > count)
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break;
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memcpy(buf + buf_pos, entry, entry_len);
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buf_pos += entry_len;
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}
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p += entry_len;
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}
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mutex_unlock(&map->cache_lock);
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kfree(entry);
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ret = buf_pos;
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if (copy_to_user(user_buf, buf, buf_pos)) {
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ret = -EFAULT;
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goto out_buf;
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}
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*ppos += buf_pos;
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out_buf:
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kfree(buf);
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return ret;
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}
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static const struct file_operations regmap_reg_ranges_fops = {
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.open = simple_open,
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.read = regmap_reg_ranges_read_file,
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.llseek = default_llseek,
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};
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static int regmap_access_show(struct seq_file *s, void *ignored)
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{
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struct regmap *map = s->private;
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int i, reg_len;
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reg_len = regmap_calc_reg_len(map->max_register);
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for (i = 0; i <= map->max_register; i += map->reg_stride) {
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/* Ignore registers which are neither readable nor writable */
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if (!regmap_readable(map, i) && !regmap_writeable(map, i))
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continue;
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/* Format the register */
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seq_printf(s, "%.*x: %c %c %c %c\n", reg_len, i,
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regmap_readable(map, i) ? 'y' : 'n',
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regmap_writeable(map, i) ? 'y' : 'n',
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regmap_volatile(map, i) ? 'y' : 'n',
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regmap_precious(map, i) ? 'y' : 'n');
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}
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return 0;
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}
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static int access_open(struct inode *inode, struct file *file)
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{
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return single_open(file, regmap_access_show, inode->i_private);
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}
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static const struct file_operations regmap_access_fops = {
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.open = access_open,
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.read = seq_read,
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.llseek = seq_lseek,
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.release = single_release,
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};
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static ssize_t regmap_cache_only_write_file(struct file *file,
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const char __user *user_buf,
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size_t count, loff_t *ppos)
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{
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struct regmap *map = container_of(file->private_data,
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struct regmap, cache_only);
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ssize_t result;
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bool was_enabled, require_sync = false;
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int err;
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map->lock(map->lock_arg);
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was_enabled = map->cache_only;
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result = debugfs_write_file_bool(file, user_buf, count, ppos);
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if (result < 0) {
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map->unlock(map->lock_arg);
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return result;
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}
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if (map->cache_only && !was_enabled) {
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dev_warn(map->dev, "debugfs cache_only=Y forced\n");
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add_taint(TAINT_USER, LOCKDEP_STILL_OK);
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} else if (!map->cache_only && was_enabled) {
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dev_warn(map->dev, "debugfs cache_only=N forced: syncing cache\n");
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require_sync = true;
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}
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map->unlock(map->lock_arg);
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if (require_sync) {
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err = regcache_sync(map);
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if (err)
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dev_err(map->dev, "Failed to sync cache %d\n", err);
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}
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return result;
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}
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static const struct file_operations regmap_cache_only_fops = {
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.open = simple_open,
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.read = debugfs_read_file_bool,
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.write = regmap_cache_only_write_file,
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};
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static ssize_t regmap_cache_bypass_write_file(struct file *file,
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const char __user *user_buf,
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size_t count, loff_t *ppos)
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{
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struct regmap *map = container_of(file->private_data,
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struct regmap, cache_bypass);
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ssize_t result;
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bool was_enabled;
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map->lock(map->lock_arg);
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was_enabled = map->cache_bypass;
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result = debugfs_write_file_bool(file, user_buf, count, ppos);
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if (result < 0)
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goto out;
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if (map->cache_bypass && !was_enabled) {
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dev_warn(map->dev, "debugfs cache_bypass=Y forced\n");
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add_taint(TAINT_USER, LOCKDEP_STILL_OK);
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} else if (!map->cache_bypass && was_enabled) {
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dev_warn(map->dev, "debugfs cache_bypass=N forced\n");
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}
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out:
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map->unlock(map->lock_arg);
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return result;
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}
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static const struct file_operations regmap_cache_bypass_fops = {
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.open = simple_open,
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.read = debugfs_read_file_bool,
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|
.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";
|
|
|
|
/* 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(®map_debugfs_early_lock);
|
|
list_add(&node->link, ®map_debugfs_early_list);
|
|
mutex_unlock(®map_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;
|
|
}
|
|
|
|
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, ®map_name_fops);
|
|
|
|
debugfs_create_file("range", 0400, map->debugfs,
|
|
map, ®map_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, ®map_map_fops);
|
|
debugfs_create_file("access", 0400, map->debugfs,
|
|
map, ®map_access_fops);
|
|
}
|
|
|
|
if (map->cache_type) {
|
|
debugfs_create_file("cache_only", 0600, map->debugfs,
|
|
&map->cache_only, ®map_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,
|
|
®map_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,
|
|
®map_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(®map_debugfs_early_lock);
|
|
list_for_each_entry_safe(node, tmp, ®map_debugfs_early_list,
|
|
link) {
|
|
if (node->map == map) {
|
|
list_del(&node->link);
|
|
kfree(node);
|
|
}
|
|
}
|
|
mutex_unlock(®map_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(®map_debugfs_early_lock);
|
|
list_for_each_entry_safe(node, tmp, ®map_debugfs_early_list, link) {
|
|
regmap_debugfs_init(node->map, node->name);
|
|
list_del(&node->link);
|
|
kfree(node);
|
|
}
|
|
mutex_unlock(®map_debugfs_early_lock);
|
|
}
|