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![Jonathan Cameron](/assets/img/avatar_default.png)
IIO triggers are software IRQ chips that split an incoming IRQ into separate IRQs routed to all devices using the trigger. When all consumers are done then a trigger callback reenable() is called. There are a few circumstances under which this can happen in atomic context. 1) A single user of the trigger that calls the iio_trigger_done() function from interrupt context. 2) A race between disconnecting the last device from a trigger and the trigger itself sucessfully being disabled. To avoid a resulting scheduling whilst atomic, close this second corner by using schedule_work() to ensure the reenable is not done in atomic context. Note that drivers must be careful to manage the interaction of set_state() and reenable() callbacks to ensure appropriate reference counting if they are relying on the same hardware controls. Deliberately taking this the slow path rather than via a fixes tree because the error has hard to hit and I would like it to soak for a while before hitting a release kernel. Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Cc: Pengutronix Kernel Team <kernel@pengutronix.de> Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com> Tested-by: Oleksij Rempel <o.rempel@pengutronix.de> Cc: <Stable@vger.kernel.org> Link: https://lore.kernel.org/r/20211017172209.112387-1-jic23@kernel.org
183 lines
5.3 KiB
C
183 lines
5.3 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/* The industrial I/O core, trigger handling functions
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*
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* Copyright (c) 2008 Jonathan Cameron
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*/
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#include <linux/irq.h>
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#include <linux/module.h>
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#include <linux/atomic.h>
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#ifndef _IIO_TRIGGER_H_
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#define _IIO_TRIGGER_H_
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#ifdef CONFIG_IIO_TRIGGER
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struct iio_subirq {
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bool enabled;
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};
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struct iio_dev;
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struct iio_trigger;
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/**
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* struct iio_trigger_ops - operations structure for an iio_trigger.
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* @set_trigger_state: switch on/off the trigger on demand
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* @reenable: function to reenable the trigger when the
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* use count is zero (may be NULL)
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* @validate_device: function to validate the device when the
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* current trigger gets changed.
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*
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* This is typically static const within a driver and shared by
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* instances of a given device.
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**/
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struct iio_trigger_ops {
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int (*set_trigger_state)(struct iio_trigger *trig, bool state);
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void (*reenable)(struct iio_trigger *trig);
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int (*validate_device)(struct iio_trigger *trig,
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struct iio_dev *indio_dev);
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};
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/**
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* struct iio_trigger - industrial I/O trigger device
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* @ops: [DRIVER] operations structure
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* @owner: [INTERN] owner of this driver module
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* @id: [INTERN] unique id number
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* @name: [DRIVER] unique name
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* @dev: [DRIVER] associated device (if relevant)
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* @list: [INTERN] used in maintenance of global trigger list
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* @alloc_list: [DRIVER] used for driver specific trigger list
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* @use_count: [INTERN] use count for the trigger.
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* @subirq_chip: [INTERN] associate 'virtual' irq chip.
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* @subirq_base: [INTERN] base number for irqs provided by trigger.
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* @subirqs: [INTERN] information about the 'child' irqs.
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* @pool: [INTERN] bitmap of irqs currently in use.
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* @pool_lock: [INTERN] protection of the irq pool.
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* @attached_own_device:[INTERN] if we are using our own device as trigger,
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* i.e. if we registered a poll function to the same
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* device as the one providing the trigger.
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* @reenable_work: [INTERN] work item used to ensure reenable can sleep.
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**/
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struct iio_trigger {
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const struct iio_trigger_ops *ops;
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struct module *owner;
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int id;
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const char *name;
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struct device dev;
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struct list_head list;
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struct list_head alloc_list;
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atomic_t use_count;
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struct irq_chip subirq_chip;
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int subirq_base;
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struct iio_subirq subirqs[CONFIG_IIO_CONSUMERS_PER_TRIGGER];
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unsigned long pool[BITS_TO_LONGS(CONFIG_IIO_CONSUMERS_PER_TRIGGER)];
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struct mutex pool_lock;
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bool attached_own_device;
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struct work_struct reenable_work;
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};
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static inline struct iio_trigger *to_iio_trigger(struct device *d)
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{
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return container_of(d, struct iio_trigger, dev);
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}
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static inline void iio_trigger_put(struct iio_trigger *trig)
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{
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module_put(trig->owner);
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put_device(&trig->dev);
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}
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static inline struct iio_trigger *iio_trigger_get(struct iio_trigger *trig)
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{
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get_device(&trig->dev);
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__module_get(trig->owner);
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return trig;
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}
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/**
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* iio_trigger_set_drvdata() - Set trigger driver data
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* @trig: IIO trigger structure
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* @data: Driver specific data
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*
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* Allows to attach an arbitrary pointer to an IIO trigger, which can later be
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* retrieved by iio_trigger_get_drvdata().
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*/
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static inline void iio_trigger_set_drvdata(struct iio_trigger *trig, void *data)
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{
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dev_set_drvdata(&trig->dev, data);
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}
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/**
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* iio_trigger_get_drvdata() - Get trigger driver data
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* @trig: IIO trigger structure
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*
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* Returns the data previously set with iio_trigger_set_drvdata()
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*/
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static inline void *iio_trigger_get_drvdata(struct iio_trigger *trig)
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{
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return dev_get_drvdata(&trig->dev);
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}
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/**
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* iio_trigger_register() - register a trigger with the IIO core
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* @trig_info: trigger to be registered
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**/
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#define iio_trigger_register(trig_info) \
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__iio_trigger_register((trig_info), THIS_MODULE)
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int __iio_trigger_register(struct iio_trigger *trig_info,
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struct module *this_mod);
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#define devm_iio_trigger_register(dev, trig_info) \
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__devm_iio_trigger_register((dev), (trig_info), THIS_MODULE)
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int __devm_iio_trigger_register(struct device *dev,
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struct iio_trigger *trig_info,
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struct module *this_mod);
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/**
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* iio_trigger_unregister() - unregister a trigger from the core
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* @trig_info: trigger to be unregistered
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**/
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void iio_trigger_unregister(struct iio_trigger *trig_info);
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/**
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* iio_trigger_set_immutable() - set an immutable trigger on destination
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*
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* @indio_dev: IIO device structure containing the device
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* @trig: trigger to assign to device
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*
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**/
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int iio_trigger_set_immutable(struct iio_dev *indio_dev, struct iio_trigger *trig);
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/**
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* iio_trigger_poll() - called on a trigger occurring
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* @trig: trigger which occurred
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*
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* Typically called in relevant hardware interrupt handler.
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**/
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void iio_trigger_poll(struct iio_trigger *trig);
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void iio_trigger_poll_chained(struct iio_trigger *trig);
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irqreturn_t iio_trigger_generic_data_rdy_poll(int irq, void *private);
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__printf(2, 3)
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struct iio_trigger *iio_trigger_alloc(struct device *parent, const char *fmt, ...);
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void iio_trigger_free(struct iio_trigger *trig);
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/**
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* iio_trigger_using_own() - tells us if we use our own HW trigger ourselves
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* @indio_dev: device to check
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*/
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bool iio_trigger_using_own(struct iio_dev *indio_dev);
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int iio_trigger_validate_own_device(struct iio_trigger *trig,
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struct iio_dev *indio_dev);
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#else
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struct iio_trigger;
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struct iio_trigger_ops;
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#endif
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#endif /* _IIO_TRIGGER_H_ */
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