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linux-next/drivers/pinctrl/core.h
Patrice Chotard 42fed7ba44 pinctrl: move subsystem mutex to pinctrl_dev struct
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>
2013-04-26 17:01:35 +02:00

200 lines
6.4 KiB
C

/*
* Core private header for the pin control subsystem
*
* Copyright (C) 2011 ST-Ericsson SA
* Written on behalf of Linaro for ST-Ericsson
*
* Author: Linus Walleij <linus.walleij@linaro.org>
*
* License terms: GNU General Public License (GPL) version 2
*/
#include <linux/kref.h>
#include <linux/mutex.h>
#include <linux/radix-tree.h>
#include <linux/pinctrl/pinconf.h>
#include <linux/pinctrl/machine.h>
struct pinctrl_gpio_range;
/**
* struct pinctrl_dev - pin control class device
* @node: node to include this pin controller in the global pin controller list
* @desc: the pin controller descriptor supplied when initializing this pin
* controller
* @pin_desc_tree: each pin descriptor for this pin controller is stored in
* this radix tree
* @gpio_ranges: a list of GPIO ranges that is handled by this pin controller,
* ranges are added to this list at runtime
* @dev: the device entry for this pin controller
* @owner: module providing the pin controller, used for refcounting
* @driver_data: driver data for drivers registering to the pin controller
* subsystem
* @p: result of pinctrl_get() for this device
* @hog_default: default state for pins hogged by this device
* @hog_sleep: sleep state for pins hogged by this device
* @mutex: mutex taken on each pin controller specific action
* @device_root: debugfs root for this device
*/
struct pinctrl_dev {
struct list_head node;
struct pinctrl_desc *desc;
struct radix_tree_root pin_desc_tree;
struct list_head gpio_ranges;
struct device *dev;
struct module *owner;
void *driver_data;
struct pinctrl *p;
struct pinctrl_state *hog_default;
struct pinctrl_state *hog_sleep;
struct mutex mutex;
#ifdef CONFIG_DEBUG_FS
struct dentry *device_root;
#endif
};
/**
* struct pinctrl - per-device pin control state holder
* @node: global list node
* @dev: the device using this pin control handle
* @states: a list of states for this device
* @state: the current state
* @dt_maps: the mapping table chunks dynamically parsed from device tree for
* this device, if any
* @users: reference count
*/
struct pinctrl {
struct list_head node;
struct device *dev;
struct list_head states;
struct pinctrl_state *state;
struct list_head dt_maps;
struct kref users;
};
/**
* struct pinctrl_state - a pinctrl state for a device
* @node: list node for struct pinctrl's @states field
* @name: the name of this state
* @settings: a list of settings for this state
*/
struct pinctrl_state {
struct list_head node;
const char *name;
struct list_head settings;
};
/**
* struct pinctrl_setting_mux - setting data for MAP_TYPE_MUX_GROUP
* @group: the group selector to program
* @func: the function selector to program
*/
struct pinctrl_setting_mux {
unsigned group;
unsigned func;
};
/**
* struct pinctrl_setting_configs - setting data for MAP_TYPE_CONFIGS_*
* @group_or_pin: the group selector or pin ID to program
* @configs: a pointer to an array of config parameters/values to program into
* hardware. Each individual pin controller defines the format and meaning
* of config parameters.
* @num_configs: the number of entries in array @configs
*/
struct pinctrl_setting_configs {
unsigned group_or_pin;
unsigned long *configs;
unsigned num_configs;
};
/**
* struct pinctrl_setting - an individual mux or config setting
* @node: list node for struct pinctrl_settings's @settings field
* @type: the type of setting
* @pctldev: pin control device handling to be programmed. Not used for
* PIN_MAP_TYPE_DUMMY_STATE.
* @dev_name: the name of the device using this state
* @data: Data specific to the setting type
*/
struct pinctrl_setting {
struct list_head node;
enum pinctrl_map_type type;
struct pinctrl_dev *pctldev;
const char *dev_name;
union {
struct pinctrl_setting_mux mux;
struct pinctrl_setting_configs configs;
} data;
};
/**
* struct pin_desc - pin descriptor for each physical pin in the arch
* @pctldev: corresponding pin control device
* @name: a name for the pin, e.g. the name of the pin/pad/finger on a
* datasheet or such
* @dynamic_name: if the name of this pin was dynamically allocated
* @mux_usecount: If zero, the pin is not claimed, and @owner should be NULL.
* If non-zero, this pin is claimed by @owner. This field is an integer
* rather than a boolean, since pinctrl_get() might process multiple
* mapping table entries that refer to, and hence claim, the same group
* or pin, and each of these will increment the @usecount.
* @mux_owner: The name of device that called pinctrl_get().
* @mux_setting: The most recent selected mux setting for this pin, if any.
* @gpio_owner: If pinctrl_request_gpio() was called for this pin, this is
* the name of the GPIO that "owns" this pin.
*/
struct pin_desc {
struct pinctrl_dev *pctldev;
const char *name;
bool dynamic_name;
/* These fields only added when supporting pinmux drivers */
#ifdef CONFIG_PINMUX
unsigned mux_usecount;
const char *mux_owner;
const struct pinctrl_setting_mux *mux_setting;
const char *gpio_owner;
#endif
};
/**
* struct pinctrl_maps - a list item containing part of the mapping table
* @node: mapping table list node
* @maps: array of mapping table entries
* @num_maps: the number of entries in @maps
*/
struct pinctrl_maps {
struct list_head node;
struct pinctrl_map const *maps;
unsigned num_maps;
};
struct pinctrl_dev *get_pinctrl_dev_from_devname(const char *dev_name);
struct pinctrl_dev *get_pinctrl_dev_from_of_node(struct device_node *np);
int pin_get_from_name(struct pinctrl_dev *pctldev, const char *name);
const char *pin_get_name(struct pinctrl_dev *pctldev, const unsigned pin);
int pinctrl_get_group_selector(struct pinctrl_dev *pctldev,
const char *pin_group);
static inline struct pin_desc *pin_desc_get(struct pinctrl_dev *pctldev,
unsigned int pin)
{
return radix_tree_lookup(&pctldev->pin_desc_tree, pin);
}
int pinctrl_register_map(struct pinctrl_map const *maps, unsigned num_maps,
bool dup, bool locked);
void pinctrl_unregister_map(struct pinctrl_map const *map);
extern int pinctrl_force_sleep(struct pinctrl_dev *pctldev);
extern int pinctrl_force_default(struct pinctrl_dev *pctldev);
extern struct mutex pinctrl_maps_mutex;
extern struct list_head pinctrl_maps;
#define for_each_maps(_maps_node_, _i_, _map_) \
list_for_each_entry(_maps_node_, &pinctrl_maps, node) \
for (_i_ = 0, _map_ = &_maps_node_->maps[_i_]; \
_i_ < _maps_node_->num_maps; \
_i_++, _map_ = &_maps_node_->maps[_i_])