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42fed7ba44
This mutex avoids deadlock in case of use of multiple pin controllers. Before this modification, by using a global mutex, deadlock appeared when, for example, a call to pinctrl_pins_show() locked the pinctrl_mutex, called the ops->pin_dbg_show of a particular pin controller. If this pin controller needs I2C access to retrieve configuration information and I2C driver is using pinctrl to drive its pins, a call to pinctrl_select_state() try to lock again pinctrl_mutex which leads to a deadlock. Notice that the mutex grab from the two direction functions was moved into pinctrl_gpio_direction(). For several cases, we can't replace pinctrl_mutex by pctldev->mutex, because at this stage, pctldev is not accessible : - pinctrl_get()/pinctrl_put() - pinctrl_register_maps() So add respectively pinctrl_list_mutex and pinctrl_maps_mutex in order to protect pinctrl_list and pinctrl_maps list instead. Reintroduce pinctrldev_list_mutex in find_pinctrl_by_of_node(), pinctrl_find_and_add_gpio_range() pinctrl_request_gpio(), pinctrl_free_gpio(), pinctrl_gpio_direction(), pinctrl_devices_show(), pinctrl_register() and pinctrl_unregister() to protect pinctrldev_list. Changes v2->v3: - Fix a missing EXPORT_SYMBOL_GPL() for pinctrl_select_state(). Changes v1->v2: - pinctrl_select_state_locked() is removed, all lock mechanism is located inside pinctrl_select_state(). When parsing the state->setting list, take the per-pin-controller driver lock. (Patrice). - Introduce pinctrldev_list_mutex to protect pinctrldev_list in all functions which parse or modify pictrldev_list. (Patrice). - move find_pinctrl_by_of_node() from pinctrl/devicetree.c to pinctrl/core.c in order to protect pinctrldev_list. (Patrice). - Sink mutex:es into some functions and remove some _locked variants down to where the lists are actually accessed to make things simpler. (Linus) - Drop *all* mutexes completely from pinctrl_lookup_state() and pinctrl_select_state() - no relevant mutex was taken and it was unclear what this was protecting against. (Linus) Reported by : Seraphin Bonnaffe <seraphin.bonnaffe@stericsson.com> Signed-off-by: Patrice Chotard <patrice.chotard@st.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
255 lines
6.6 KiB
C
255 lines
6.6 KiB
C
/*
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* Device tree integration for the pin control subsystem
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*
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* Copyright (C) 2012 NVIDIA CORPORATION. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <linux/device.h>
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#include <linux/of.h>
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#include <linux/pinctrl/pinctrl.h>
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#include <linux/slab.h>
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#include "core.h"
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#include "devicetree.h"
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/**
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* struct pinctrl_dt_map - mapping table chunk parsed from device tree
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* @node: list node for struct pinctrl's @dt_maps field
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* @pctldev: the pin controller that allocated this struct, and will free it
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* @maps: the mapping table entries
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*/
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struct pinctrl_dt_map {
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struct list_head node;
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struct pinctrl_dev *pctldev;
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struct pinctrl_map *map;
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unsigned num_maps;
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};
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static void dt_free_map(struct pinctrl_dev *pctldev,
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struct pinctrl_map *map, unsigned num_maps)
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{
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if (pctldev) {
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const struct pinctrl_ops *ops = pctldev->desc->pctlops;
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ops->dt_free_map(pctldev, map, num_maps);
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} else {
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/* There is no pctldev for PIN_MAP_TYPE_DUMMY_STATE */
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kfree(map);
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}
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}
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void pinctrl_dt_free_maps(struct pinctrl *p)
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{
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struct pinctrl_dt_map *dt_map, *n1;
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list_for_each_entry_safe(dt_map, n1, &p->dt_maps, node) {
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pinctrl_unregister_map(dt_map->map);
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list_del(&dt_map->node);
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dt_free_map(dt_map->pctldev, dt_map->map,
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dt_map->num_maps);
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kfree(dt_map);
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}
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of_node_put(p->dev->of_node);
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}
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static int dt_remember_or_free_map(struct pinctrl *p, const char *statename,
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struct pinctrl_dev *pctldev,
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struct pinctrl_map *map, unsigned num_maps)
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{
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int i;
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struct pinctrl_dt_map *dt_map;
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/* Initialize common mapping table entry fields */
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for (i = 0; i < num_maps; i++) {
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map[i].dev_name = dev_name(p->dev);
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map[i].name = statename;
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if (pctldev)
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map[i].ctrl_dev_name = dev_name(pctldev->dev);
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}
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/* Remember the converted mapping table entries */
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dt_map = kzalloc(sizeof(*dt_map), GFP_KERNEL);
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if (!dt_map) {
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dev_err(p->dev, "failed to alloc struct pinctrl_dt_map\n");
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dt_free_map(pctldev, map, num_maps);
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return -ENOMEM;
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}
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dt_map->pctldev = pctldev;
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dt_map->map = map;
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dt_map->num_maps = num_maps;
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list_add_tail(&dt_map->node, &p->dt_maps);
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return pinctrl_register_map(map, num_maps, false, true);
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}
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struct pinctrl_dev *of_pinctrl_get(struct device_node *np)
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{
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struct pinctrl_dev *pctldev;
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pctldev = get_pinctrl_dev_from_of_node(np);
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if (!pctldev)
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return NULL;
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return pctldev;
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}
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static int dt_to_map_one_config(struct pinctrl *p, const char *statename,
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struct device_node *np_config)
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{
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struct device_node *np_pctldev;
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struct pinctrl_dev *pctldev;
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const struct pinctrl_ops *ops;
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int ret;
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struct pinctrl_map *map;
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unsigned num_maps;
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/* Find the pin controller containing np_config */
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np_pctldev = of_node_get(np_config);
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for (;;) {
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np_pctldev = of_get_next_parent(np_pctldev);
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if (!np_pctldev || of_node_is_root(np_pctldev)) {
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dev_info(p->dev, "could not find pctldev for node %s, deferring probe\n",
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np_config->full_name);
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of_node_put(np_pctldev);
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/* OK let's just assume this will appear later then */
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return -EPROBE_DEFER;
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}
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pctldev = get_pinctrl_dev_from_of_node(np_pctldev);
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if (pctldev)
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break;
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/* Do not defer probing of hogs (circular loop) */
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if (np_pctldev == p->dev->of_node) {
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of_node_put(np_pctldev);
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return -ENODEV;
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}
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}
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of_node_put(np_pctldev);
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/*
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* Call pinctrl driver to parse device tree node, and
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* generate mapping table entries
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*/
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ops = pctldev->desc->pctlops;
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if (!ops->dt_node_to_map) {
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dev_err(p->dev, "pctldev %s doesn't support DT\n",
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dev_name(pctldev->dev));
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return -ENODEV;
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}
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ret = ops->dt_node_to_map(pctldev, np_config, &map, &num_maps);
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if (ret < 0)
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return ret;
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/* Stash the mapping table chunk away for later use */
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return dt_remember_or_free_map(p, statename, pctldev, map, num_maps);
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}
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static int dt_remember_dummy_state(struct pinctrl *p, const char *statename)
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{
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struct pinctrl_map *map;
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map = kzalloc(sizeof(*map), GFP_KERNEL);
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if (!map) {
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dev_err(p->dev, "failed to alloc struct pinctrl_map\n");
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return -ENOMEM;
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}
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/* There is no pctldev for PIN_MAP_TYPE_DUMMY_STATE */
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map->type = PIN_MAP_TYPE_DUMMY_STATE;
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return dt_remember_or_free_map(p, statename, NULL, map, 1);
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}
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int pinctrl_dt_to_map(struct pinctrl *p)
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{
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struct device_node *np = p->dev->of_node;
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int state, ret;
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char *propname;
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struct property *prop;
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const char *statename;
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const __be32 *list;
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int size, config;
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phandle phandle;
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struct device_node *np_config;
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/* CONFIG_OF enabled, p->dev not instantiated from DT */
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if (!np) {
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dev_dbg(p->dev, "no of_node; not parsing pinctrl DT\n");
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return 0;
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}
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/* We may store pointers to property names within the node */
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of_node_get(np);
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/* For each defined state ID */
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for (state = 0; ; state++) {
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/* Retrieve the pinctrl-* property */
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propname = kasprintf(GFP_KERNEL, "pinctrl-%d", state);
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prop = of_find_property(np, propname, &size);
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kfree(propname);
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if (!prop)
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break;
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list = prop->value;
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size /= sizeof(*list);
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/* Determine whether pinctrl-names property names the state */
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ret = of_property_read_string_index(np, "pinctrl-names",
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state, &statename);
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/*
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* If not, statename is just the integer state ID. But rather
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* than dynamically allocate it and have to free it later,
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* just point part way into the property name for the string.
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*/
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if (ret < 0) {
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/* strlen("pinctrl-") == 8 */
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statename = prop->name + 8;
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}
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/* For every referenced pin configuration node in it */
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for (config = 0; config < size; config++) {
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phandle = be32_to_cpup(list++);
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/* Look up the pin configuration node */
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np_config = of_find_node_by_phandle(phandle);
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if (!np_config) {
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dev_err(p->dev,
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"prop %s index %i invalid phandle\n",
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prop->name, config);
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ret = -EINVAL;
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goto err;
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}
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/* Parse the node */
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ret = dt_to_map_one_config(p, statename, np_config);
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of_node_put(np_config);
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if (ret < 0)
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goto err;
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}
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/* No entries in DT? Generate a dummy state table entry */
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if (!size) {
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ret = dt_remember_dummy_state(p, statename);
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if (ret < 0)
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goto err;
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}
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}
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return 0;
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err:
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pinctrl_dt_free_maps(p);
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return ret;
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}
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