Commit 1046f71d authored by Thomas Gleixner's avatar Thomas Gleixner
Browse files

genirq/msi: Provide a set of advanced MSI accessors and iterators 



In preparation for dynamic handling of MSI-X interrupts provide a new set
of MSI descriptor accessor functions and iterators. They are benefitial per
se as they allow to cleanup quite some code in various MSI domain
implementations.

Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Tested-by: default avatarMichael Kelley <mikelley@microsoft.com>
Tested-by: default avatarNishanth Menon <nm@ti.com>
Reviewed-by: default avatarJason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20211206210747.818635078@linutronix.de
parent 0f62d941

include/linux/msi.h

+33 −0
Original line number Diff line number Diff line
@@ -140,6 +140,18 @@ struct msi_desc { 
	struct pci_msi_desc		pci;

};



/*

 * Filter values for the MSI descriptor iterators and accessor functions.

 */

enum msi_desc_filter {

	/* All descriptors */

	MSI_DESC_ALL,

	/* Descriptors which have no interrupt associated */

	MSI_DESC_NOTASSOCIATED,

	/* Descriptors which have an interrupt associated */

	MSI_DESC_ASSOCIATED,

};



/**

 * msi_device_data - MSI per device data

 * @properties:		MSI properties which are interesting to drivers
@@ -147,6 +159,7 @@ struct msi_desc { 
 * @platform_data:	Platform-MSI specific data

 * @list:		List of MSI descriptors associated to the device

 * @mutex:		Mutex protecting the MSI list

 * @__next:		Cached pointer to the next entry for iterators

 */

struct msi_device_data {

	unsigned long			properties;
@@ -154,6 +167,7 @@ struct msi_device_data { 
	struct platform_msi_priv_data	*platform_data;

	struct list_head		list;

	struct mutex			mutex;

	struct msi_desc			*__next;

};



int msi_setup_device_data(struct device *dev);
@@ -162,6 +176,25 @@ unsigned int msi_get_virq(struct device *dev, unsigned int index); 
void msi_lock_descs(struct device *dev);

void msi_unlock_descs(struct device *dev);



struct msi_desc *msi_first_desc(struct device *dev, enum msi_desc_filter filter);

struct msi_desc *msi_next_desc(struct device *dev, enum msi_desc_filter filter);



/**

 * msi_for_each_desc - Iterate the MSI descriptors

 *

 * @desc:	struct msi_desc pointer used as iterator

 * @dev:	struct device pointer - device to iterate

 * @filter:	Filter for descriptor selection

 *

 * Notes:

 *  - The loop must be protected with a msi_lock_descs()/msi_unlock_descs()

 *    pair.

 *  - It is safe to remove a retrieved MSI descriptor in the loop.

 */

#define msi_for_each_desc(desc, dev, filter)			\

	for ((desc) = msi_first_desc((dev), (filter)); (desc);	\

	     (desc) = msi_next_desc((dev), (filter)))



/* Helpers to hide struct msi_desc implementation details */

#define msi_desc_to_dev(desc)		((desc)->dev)

#define dev_to_msi_list(dev)		(&(dev)->msi.data->list)

kernel/irq/msi.c

+96 −0
Original line number Diff line number Diff line
@@ -125,10 +125,106 @@ EXPORT_SYMBOL_GPL(msi_lock_descs); 
 */

void msi_unlock_descs(struct device *dev)

{

	/* Clear the next pointer which was cached by the iterator */

	dev->msi.data->__next = NULL;

	mutex_unlock(&dev->msi.data->mutex);

}

EXPORT_SYMBOL_GPL(msi_unlock_descs);



static bool msi_desc_match(struct msi_desc *desc, enum msi_desc_filter filter)

{

	switch (filter) {

	case MSI_DESC_ALL:

		return true;

	case MSI_DESC_NOTASSOCIATED:

		return !desc->irq;

	case MSI_DESC_ASSOCIATED:

		return !!desc->irq;

	}

	WARN_ON_ONCE(1);

	return false;

}



static struct msi_desc *msi_find_first_desc(struct device *dev, enum msi_desc_filter filter)

{

	struct msi_desc *desc;



	list_for_each_entry(desc, dev_to_msi_list(dev), list) {

		if (msi_desc_match(desc, filter))

			return desc;

	}

	return NULL;

}



/**

 * msi_first_desc - Get the first MSI descriptor of a device

 * @dev:	Device to operate on

 * @filter:	Descriptor state filter

 *

 * Must be called with the MSI descriptor mutex held, i.e. msi_lock_descs()

 * must be invoked before the call.

 *

 * Return: Pointer to the first MSI descriptor matching the search

 *	   criteria, NULL if none found.

 */

struct msi_desc *msi_first_desc(struct device *dev, enum msi_desc_filter filter)

{

	struct msi_desc *desc;



	if (WARN_ON_ONCE(!dev->msi.data))

		return NULL;



	lockdep_assert_held(&dev->msi.data->mutex);



	desc = msi_find_first_desc(dev, filter);

	dev->msi.data->__next = desc ? list_next_entry(desc, list) : NULL;

	return desc;

}

EXPORT_SYMBOL_GPL(msi_first_desc);



static struct msi_desc *__msi_next_desc(struct device *dev, enum msi_desc_filter filter,

					struct msi_desc *from)

{

	struct msi_desc *desc = from;



	list_for_each_entry_from(desc, dev_to_msi_list(dev), list) {

		if (msi_desc_match(desc, filter))

			return desc;

	}

	return NULL;

}



/**

 * msi_next_desc - Get the next MSI descriptor of a device

 * @dev:	Device to operate on

 *

 * The first invocation of msi_next_desc() has to be preceeded by a

 * successful incovation of __msi_first_desc(). Consecutive invocations are

 * only valid if the previous one was successful. All these operations have

 * to be done within the same MSI mutex held region.

 *

 * Return: Pointer to the next MSI descriptor matching the search

 *	   criteria, NULL if none found.

 */

struct msi_desc *msi_next_desc(struct device *dev, enum msi_desc_filter filter)

{

	struct msi_device_data *data = dev->msi.data;

	struct msi_desc *desc;



	if (WARN_ON_ONCE(!data))

		return NULL;



	lockdep_assert_held(&data->mutex);



	if (!data->__next)

		return NULL;



	desc = __msi_next_desc(dev, filter, data->__next);

	dev->msi.data->__next = desc ? list_next_entry(desc, list) : NULL;

	return desc;

}

EXPORT_SYMBOL_GPL(msi_next_desc);



/**

 * msi_get_virq - Return Linux interrupt number of a MSI interrupt

 * @dev:	Device to operate on