linux/drivers/pinctrl/devicetree.c
Doug Anderson c5272a2856 pinctrl: Don't just pretend to protect pinctrl_maps, do it for real
Way back, when the world was a simpler place and there was no war, no
evil, and no kernel bugs, there was just a single pinctrl lock.  That
was how the world was when (57291ce pinctrl: core device tree mapping
table parsing support) was written.  In that case, there were
instances where the pinctrl mutex was already held when
pinctrl_register_map() was called, hence a "locked" parameter was
passed to the function to indicate that the mutex was already locked
(so we shouldn't lock it again).

A few years ago in (42fed7b pinctrl: move subsystem mutex to
pinctrl_dev struct), we switched to a separate pinctrl_maps_mutex.
...but (oops) we forgot to re-think about the whole "locked" parameter
for pinctrl_register_map().  Basically the "locked" parameter appears
to still refer to whether the bigger pinctrl_dev mutex is locked, but
we're using it to skip locks of our (now separate) pinctrl_maps_mutex.

That's kind of a bad thing(TM).  Probably nobody noticed because most
of the calls to pinctrl_register_map happen at boot time and we've got
synchronous device probing.  ...and even cases where we're
asynchronous don't end up actually hitting the race too often.  ...but
after banging my head against the wall for a bug that reproduced 1 out
of 1000 reboots and lots of looking through kgdb, I finally noticed
this.

Anyway, we can now safely remove the "locked" parameter and go back to
a war-free, evil-free, and kernel-bug-free world.

Fixes: 42fed7ba44 ("pinctrl: move subsystem mutex to pinctrl_dev struct")
Signed-off-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2015-05-06 16:24:28 +02:00

257 lines
6.6 KiB
C

/*
* Device tree integration for the pin control subsystem
*
* Copyright (C) 2012 NVIDIA CORPORATION. All rights reserved.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <linux/device.h>
#include <linux/of.h>
#include <linux/pinctrl/pinctrl.h>
#include <linux/slab.h>
#include "core.h"
#include "devicetree.h"
/**
* struct pinctrl_dt_map - mapping table chunk parsed from device tree
* @node: list node for struct pinctrl's @dt_maps field
* @pctldev: the pin controller that allocated this struct, and will free it
* @maps: the mapping table entries
*/
struct pinctrl_dt_map {
struct list_head node;
struct pinctrl_dev *pctldev;
struct pinctrl_map *map;
unsigned num_maps;
};
static void dt_free_map(struct pinctrl_dev *pctldev,
struct pinctrl_map *map, unsigned num_maps)
{
if (pctldev) {
const struct pinctrl_ops *ops = pctldev->desc->pctlops;
ops->dt_free_map(pctldev, map, num_maps);
} else {
/* There is no pctldev for PIN_MAP_TYPE_DUMMY_STATE */
kfree(map);
}
}
void pinctrl_dt_free_maps(struct pinctrl *p)
{
struct pinctrl_dt_map *dt_map, *n1;
list_for_each_entry_safe(dt_map, n1, &p->dt_maps, node) {
pinctrl_unregister_map(dt_map->map);
list_del(&dt_map->node);
dt_free_map(dt_map->pctldev, dt_map->map,
dt_map->num_maps);
kfree(dt_map);
}
of_node_put(p->dev->of_node);
}
static int dt_remember_or_free_map(struct pinctrl *p, const char *statename,
struct pinctrl_dev *pctldev,
struct pinctrl_map *map, unsigned num_maps)
{
int i;
struct pinctrl_dt_map *dt_map;
/* Initialize common mapping table entry fields */
for (i = 0; i < num_maps; i++) {
map[i].dev_name = dev_name(p->dev);
map[i].name = statename;
if (pctldev)
map[i].ctrl_dev_name = dev_name(pctldev->dev);
}
/* Remember the converted mapping table entries */
dt_map = kzalloc(sizeof(*dt_map), GFP_KERNEL);
if (!dt_map) {
dev_err(p->dev, "failed to alloc struct pinctrl_dt_map\n");
dt_free_map(pctldev, map, num_maps);
return -ENOMEM;
}
dt_map->pctldev = pctldev;
dt_map->map = map;
dt_map->num_maps = num_maps;
list_add_tail(&dt_map->node, &p->dt_maps);
return pinctrl_register_map(map, num_maps, false);
}
struct pinctrl_dev *of_pinctrl_get(struct device_node *np)
{
struct pinctrl_dev *pctldev;
pctldev = get_pinctrl_dev_from_of_node(np);
if (!pctldev)
return NULL;
return pctldev;
}
static int dt_to_map_one_config(struct pinctrl *p, const char *statename,
struct device_node *np_config)
{
struct device_node *np_pctldev;
struct pinctrl_dev *pctldev;
const struct pinctrl_ops *ops;
int ret;
struct pinctrl_map *map;
unsigned num_maps;
/* Find the pin controller containing np_config */
np_pctldev = of_node_get(np_config);
for (;;) {
np_pctldev = of_get_next_parent(np_pctldev);
if (!np_pctldev || of_node_is_root(np_pctldev)) {
dev_info(p->dev, "could not find pctldev for node %s, deferring probe\n",
np_config->full_name);
of_node_put(np_pctldev);
/* OK let's just assume this will appear later then */
return -EPROBE_DEFER;
}
pctldev = get_pinctrl_dev_from_of_node(np_pctldev);
if (pctldev)
break;
/* Do not defer probing of hogs (circular loop) */
if (np_pctldev == p->dev->of_node) {
of_node_put(np_pctldev);
return -ENODEV;
}
}
of_node_put(np_pctldev);
/*
* Call pinctrl driver to parse device tree node, and
* generate mapping table entries
*/
ops = pctldev->desc->pctlops;
if (!ops->dt_node_to_map) {
dev_err(p->dev, "pctldev %s doesn't support DT\n",
dev_name(pctldev->dev));
return -ENODEV;
}
ret = ops->dt_node_to_map(pctldev, np_config, &map, &num_maps);
if (ret < 0)
return ret;
/* Stash the mapping table chunk away for later use */
return dt_remember_or_free_map(p, statename, pctldev, map, num_maps);
}
static int dt_remember_dummy_state(struct pinctrl *p, const char *statename)
{
struct pinctrl_map *map;
map = kzalloc(sizeof(*map), GFP_KERNEL);
if (!map) {
dev_err(p->dev, "failed to alloc struct pinctrl_map\n");
return -ENOMEM;
}
/* There is no pctldev for PIN_MAP_TYPE_DUMMY_STATE */
map->type = PIN_MAP_TYPE_DUMMY_STATE;
return dt_remember_or_free_map(p, statename, NULL, map, 1);
}
int pinctrl_dt_to_map(struct pinctrl *p)
{
struct device_node *np = p->dev->of_node;
int state, ret;
char *propname;
struct property *prop;
const char *statename;
const __be32 *list;
int size, config;
phandle phandle;
struct device_node *np_config;
/* CONFIG_OF enabled, p->dev not instantiated from DT */
if (!np) {
if (of_have_populated_dt())
dev_dbg(p->dev,
"no of_node; not parsing pinctrl DT\n");
return 0;
}
/* We may store pointers to property names within the node */
of_node_get(np);
/* For each defined state ID */
for (state = 0; ; state++) {
/* Retrieve the pinctrl-* property */
propname = kasprintf(GFP_KERNEL, "pinctrl-%d", state);
prop = of_find_property(np, propname, &size);
kfree(propname);
if (!prop)
break;
list = prop->value;
size /= sizeof(*list);
/* Determine whether pinctrl-names property names the state */
ret = of_property_read_string_index(np, "pinctrl-names",
state, &statename);
/*
* If not, statename is just the integer state ID. But rather
* than dynamically allocate it and have to free it later,
* just point part way into the property name for the string.
*/
if (ret < 0) {
/* strlen("pinctrl-") == 8 */
statename = prop->name + 8;
}
/* For every referenced pin configuration node in it */
for (config = 0; config < size; config++) {
phandle = be32_to_cpup(list++);
/* Look up the pin configuration node */
np_config = of_find_node_by_phandle(phandle);
if (!np_config) {
dev_err(p->dev,
"prop %s index %i invalid phandle\n",
prop->name, config);
ret = -EINVAL;
goto err;
}
/* Parse the node */
ret = dt_to_map_one_config(p, statename, np_config);
of_node_put(np_config);
if (ret < 0)
goto err;
}
/* No entries in DT? Generate a dummy state table entry */
if (!size) {
ret = dt_remember_dummy_state(p, statename);
if (ret < 0)
goto err;
}
}
return 0;
err:
pinctrl_dt_free_maps(p);
return ret;
}