drivers/mux/core.c

10 #define pr_fmt(fmt) "mux-core: " fmt
19 #include <linux/mux/consumer.h>
20 #include <linux/mux/driver.h>
32  * struct mux_state -	Represents a mux controller state specific to a given
34  * @mux:		Pointer to a mux controller.
35  * @state:		State of the mux to be selected.
41 	struct mux_control *mux;
46 	.name = "mux",
50  * struct devm_mux_state_state -	Tracks managed resources for mux-state objects.
51  * @mstate:				Pointer to a mux state.
82 	.name = "mux-chip",
87  * mux_chip_alloc() - Allocate a mux-chip.
88  * @dev: The parent device implementing the mux interface.
89  * @controllers: The number of mux controllers to allocate for this chip.
92  * After allocating the mux-chip with the desired number of mux controllers
93  * but before registering the chip, the mux driver is required to configure
94  * the number of valid mux states in the mux_chip->mux[N].states members and
95  * the desired idle state in the returned mux_chip->mux[N].idle_state members.
96  * The default idle state is MUX_IDLE_AS_IS. The mux driver also needs to
98  * before registering the mux-chip with mux_chip_register.
100  * Return: A pointer to the new mux-chip, or an ERR_PTR with a negative errno.
111 	mux_chip = kzalloc(size_add(struct_size(mux_chip, mux, controllers),
135 		struct mux_control *mux = &mux_chip->mux[i];
137 		mux->chip = mux_chip;
138 		sema_init(&mux->lock, 1);
139 		mux->cached_state = MUX_CACHE_UNKNOWN;
140 		mux->idle_state = MUX_IDLE_AS_IS;
141 		mux->last_change = ktime_get();
150 static int mux_control_set(struct mux_control *mux, int state)
152 	int ret = mux->chip->ops->set(mux, state);
154 	mux->cached_state = ret < 0 ? MUX_CACHE_UNKNOWN : state;
156 		mux->last_change = ktime_get();
162  * mux_chip_register() - Register a mux-chip, thus readying the controllers
164  * @mux_chip: The mux-chip to register.
166  * Do not retry registration of the same mux-chip on failure. You should
178 		struct mux_control *mux = &mux_chip->mux[i];
180 		if (mux->idle_state == mux->cached_state)
183 		ret = mux_control_set(mux, mux->idle_state);
199  * mux_chip_unregister() - Take the mux-chip off-line.
200  * @mux_chip: The mux-chip to unregister.
204  * on a mux-chip that has been registered before.
213  * mux_chip_free() - Free the mux-chip for good.
214  * @mux_chip: The mux-chip to free.
236  * @dev: The parent device implementing the mux interface.
237  * @controllers: The number of mux controllers to allocate for this chip.
242  * Return: A pointer to the new mux-chip, or an ERR_PTR with a negative errno.
276  * @dev: The parent device implementing the mux interface.
277  * @mux_chip: The mux-chip to register.
308  * @mux: The mux-control to query.
312 unsigned int mux_control_states(struct mux_control *mux)
314 	return mux->states;
319  * The mux->lock must be down when calling this function.
321 static int __mux_control_select(struct mux_control *mux, int state)
325 	if (WARN_ON(state < 0 || state >= mux->states))
328 	if (mux->cached_state == state)
331 	ret = mux_control_set(mux, state);
335 	/* The mux update failed, try to revert if appropriate... */
336 	if (mux->idle_state != MUX_IDLE_AS_IS)
337 		mux_control_set(mux, mux->idle_state);
342 static void mux_control_delay(struct mux_control *mux, unsigned int delay_us)
350 	delayend = ktime_add_us(mux->last_change, delay_us);
358  * @mux: The mux-control to request a change of state from.
360  * @delay_us: The time to delay (in microseconds) if the mux state is changed.
362  * On successfully selecting the mux-control state, it will be locked until
363  * there is a call to mux_control_deselect(). If the mux-control is already
369  * complete and the mux-control is free for others to use, but do not call
372  * Return: 0 when the mux-control state has the requested state or a negative
375 int mux_control_select_delay(struct mux_control *mux, unsigned int state,
380 	ret = down_killable(&mux->lock);
384 	ret = __mux_control_select(mux, state);
386 		mux_control_delay(mux, delay_us);
389 		up(&mux->lock);
397  * @mstate: The mux-state to select.
398  * @delay_us: The time to delay (in microseconds) if the mux state is changed.
400  * On successfully selecting the mux-state, its mux-control will be locked
401  * until there is a call to mux_state_deselect(). If the mux-control is already
407  * complete and the mux-control is free for others to use, but do not call
410  * Return: 0 when the mux-state has been selected or a negative
415 	return mux_control_select_delay(mstate->mux, mstate->state, delay_us);
421  * @mux: The mux-control to request a change of state from.
423  * @delay_us: The time to delay (in microseconds) if the mux state is changed.
425  * On successfully selecting the mux-control state, it will be locked until
429  * complete and the mux-control is free for others to use, but do not call
432  * Return: 0 when the mux-control state has the requested state or a negative
433  * errno on error. Specifically -EBUSY if the mux-control is contended.
435 int mux_control_try_select_delay(struct mux_control *mux, unsigned int state,
440 	if (down_trylock(&mux->lock))
443 	ret = __mux_control_select(mux, state);
445 		mux_control_delay(mux, delay_us);
448 		up(&mux->lock);
456  * @mstate: The mux-state to select.
457  * @delay_us: The time to delay (in microseconds) if the mux state is changed.
459  * On successfully selecting the mux-state, its mux-control will be locked
463  * complete and the mux-control is free for others to use, but do not call
466  * Return: 0 when the mux-state has been selected or a negative errno on
467  * error. Specifically -EBUSY if the mux-control is contended.
471 	return mux_control_try_select_delay(mstate->mux, mstate->state, delay_us);
477  * @mux: The mux-control to deselect.
484  * occur if the mux has an idle state. Note that even if an error occurs, the
485  * mux-control is unlocked and is thus free for the next access.
487 int mux_control_deselect(struct mux_control *mux)
491 	if (mux->idle_state != MUX_IDLE_AS_IS &&
492 	    mux->idle_state != mux->cached_state)
493 		ret = mux_control_set(mux, mux->idle_state);
495 	up(&mux->lock);
503  * @mstate: The mux-state to deselect.
510  * occur if the mux has an idle state. Note that even if an error occurs, the
511  * mux-control is unlocked and is thus free for the next access.
515 	return mux_control_deselect(mstate->mux);
530  * mux_get() - Get the mux-control for a device.
531  * @dev: The device that needs a mux-control.
532  * @mux_name: The name identifying the mux-control.
535  * @optional: Whether to return NULL and silence errors when mux doesn't exist.
537  * Return: Pointer to the mux-control on success, an ERR_PTR with a negative
538  * errno on error, or NULL if optional is true and mux doesn't exist.
552 			index = of_property_match_string(np, "mux-state-names",
555 			index = of_property_match_string(np, "mux-control-names",
560 			dev_err(dev, "mux controller '%s' not found\n",
568 						 "mux-states", "#mux-state-cells",
572 						 "mux-controls", "#mux-control-cells",
578 		dev_err(dev, "%pOF: failed to get mux-%s %s(%i)\n",
593 			dev_err(dev, "%pOF: wrong #mux-state-cells for %pOF\n",
609 			dev_err(dev, "%pOF: wrong #mux-control-cells for %pOF\n",
620 		dev_err(dev, "%pOF: bad mux controller %u specified in %pOF\n",
626 	return &mux_chip->mux[controller];
630  * mux_control_get() - Get the mux-control for a device.
631  * @dev: The device that needs a mux-control.
632  * @mux_name: The name identifying the mux-control.
634  * Return: A pointer to the mux-control, or an ERR_PTR with a negative errno.
638 	struct mux_control *mux = mux_get(dev, mux_name, NULL, false);
640 	if (!mux)
643 	return mux;
648  * mux_control_get_optional() - Get the optional mux-control for a device.
649  * @dev: The device that needs a mux-control.
650  * @mux_name: The name identifying the mux-control.
652  * Return: Pointer to the mux-control on success, an ERR_PTR with a negative
653  * errno on error, or NULL if mux doesn't exist.
662  * mux_control_put() - Put away the mux-control for good.
663  * @mux: The mux-control to put away.
667 void mux_control_put(struct mux_control *mux)
669 	put_device(&mux->chip->dev);
675 	struct mux_control *mux = *(struct mux_control **)res;
677 	mux_control_put(mux);
681  * devm_mux_control_get() - Get the mux-control for a device, with resource
683  * @dev: The device that needs a mux-control.
684  * @mux_name: The name identifying the mux-control.
686  * Return: Pointer to the mux-control, or an ERR_PTR with a negative errno.
691 	struct mux_control **ptr, *mux;
697 	mux = mux_control_get(dev, mux_name);
698 	if (IS_ERR(mux)) {
700 		return mux;
703 	*ptr = mux;
706 	return mux;
711  * mux_state_get() - Get the mux-state for a device.
712  * @dev: The device that needs a mux-state.
713  * @mux_name: The name identifying the mux-state.
714  * @optional: Whether to return NULL and silence errors when mux doesn't exist.
716  * Return: Pointer to the mux-state on success, an ERR_PTR with a negative
717  * errno on error, or NULL if optional is true and mux doesn't exist.
727 	mstate->mux = mux_get(dev, mux_name, &mstate->state, optional);
728 	if (IS_ERR(mstate->mux)) {
729 		int err = PTR_ERR(mstate->mux);
733 	} else if (!mstate->mux) {
742  * mux_state_put() - Put away the mux-state for good.
743  * @mstate: The mux-state to put away.
749 	mux_control_put(mstate->mux);
764  * __devm_mux_state_get() - Get the optional mux-state for a device,
766  * @dev: The device that needs a mux-state.
767  * @mux_name: The name identifying the mux-state.
768  * @optional: Whether to return NULL and silence errors when mux doesn't exist.
769  * @init: Optional function pointer for mux-state object initialisation.
770  * @exit: Optional function pointer for mux-state object cleanup on release.
772  * Return: Pointer to the mux-state on success, an ERR_PTR with a negative
773  * errno on error, or NULL if optional is true and mux doesn't exist.
818  * devm_mux_state_get() - Get the mux-state for a device, with resource
820  * @dev: The device that needs a mux-control.
821  * @mux_name: The name identifying the mux-control.
823  * Return: Pointer to the mux-state, or an ERR_PTR with a negative errno.
825  * The mux-state will automatically be freed on release.
834  * devm_mux_state_get_optional() - Get the optional mux-state for a device,
836  * @dev: The device that needs a mux-state.
837  * @mux_name: The name identifying the mux-state.
839  * Return: Pointer to the mux-state on success, an ERR_PTR with a negative
840  * errno on error, or NULL if mux doesn't exist.
842  * The mux-state will automatically be freed on release.
851  * devm_mux_state_get_selected() - Get the mux-state for a device, with
853  * @dev: The device that needs a mux-state.
854  * @mux_name: The name identifying the mux-state.
856  * Return: Pointer to the mux-state, or an ERR_PTR with a negative errno.
858  * The returned mux-state (if valid) is already selected.
860  * The mux-state will automatically be deselected and freed on release.
869  * devm_mux_state_get_optional_selected() - Get the optional mux-state for
871  * @dev: The device that needs a mux-state.
872  * @mux_name: The name identifying the mux-state.
874  * Return: Pointer to the mux-state on success, an ERR_PTR with a negative
875  * errno on error, or NULL if mux doesn't exist.
877  * The returned mux-state (if valid) is already selected.
879  * The mux-state will automatically be deselected and freed on release.
890  * the non-modular case - that the subsystem is initialized when mux consumers
891  * and mux controllers start to use it.