a1a8e1dc11
When using more than one trigger consumer it can happen that multiple threads perform a read-modify-update cycle on 'use_count' concurrently. This can cause updates to be lost and use_count can get stuck at non-zero value, in which case the IIO core assumes that at least one thread is still running and will wait for it to finish before running any trigger handlers again. This effectively renders the trigger disabled and a reboot is necessary before it can be used again. To fix this make use_count an atomic variable. Also set it to the number of consumers before starting the first consumer, otherwise it might happen that use_count drops to 0 even though not all consumers have been run yet. Signed-off-by: Lars-Peter Clausen <lars@metafoo.de> Tested-by: Denis Ciocca <denis.ciocca@st.com> Signed-off-by: Jonathan Cameron <jic23@kernel.org>
149 lines
4.2 KiB
C
149 lines
4.2 KiB
C
/* 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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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published by
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* the Free Software Foundation.
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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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/**
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* struct iio_trigger_ops - operations structure for an iio_trigger.
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* @owner: used to monitor usage count of the trigger.
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* @set_trigger_state: switch on/off the trigger on demand
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* @try_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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struct module *owner;
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int (*set_trigger_state)(struct iio_trigger *trig, bool state);
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int (*try_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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* @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: 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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**/
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struct iio_trigger {
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const struct iio_trigger_ops *ops;
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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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};
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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->ops->owner);
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put_device(&trig->dev);
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}
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static inline void 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->ops->owner);
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}
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/**
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* iio_device_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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int iio_trigger_register(struct iio_trigger *trig_info);
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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_poll() - called on a trigger occurring
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* @trig: trigger which occurred
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* @time: timestamp when trigger 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, s64 time);
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void iio_trigger_poll_chained(struct iio_trigger *trig, s64 time);
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irqreturn_t iio_trigger_generic_data_rdy_poll(int irq, void *private);
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__printf(1, 2) struct iio_trigger *iio_trigger_alloc(const char *fmt, ...);
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void iio_trigger_free(struct iio_trigger *trig);
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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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