Commit d780c371 authored by Martin Sperl's avatar Martin Sperl Committed by Mark Brown
Browse files

spi: core: added spi_resource management 



SPI resource management framework used while processing a spi_message
via the spi-core.

The basic idea is taken from devres, but as the allocation may happen
fairly frequently, some provisioning (in the form of an unused spi_device
pointer argument to spi_res_alloc) has been made so that at a later stage
we may implement reuse objects allocated earlier avoiding the repeated
allocation by keeping a cache of objects that we can reuse.

This framework can get used for:
* rewriting spi_messages
  * to fullfill alignment requirements of the spi_master HW
  * to fullfill transfer length requirements
    (e.g: transfers need to be less than 64k)
  * consolidate spi_messages with multiple transfers into a single transfer
  when the total transfer length is below a threshold.
* reimplement spi_unmap_buf without explicitly needing to check if it has
  been mapped

Signed-off-by: default avatarMartin Sperl <kernel@martin.sperl.org>
Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent 92e963f5

drivers/spi/spi.c

+91 −0
Original line number Diff line number Diff line
@@ -1024,6 +1024,8 @@ out: 
	if (msg->status && master->handle_err)

		master->handle_err(master, msg);



	spi_res_release(master, msg);



	spi_finalize_current_message(master);



	return ret;
@@ -2013,6 +2015,95 @@ struct spi_master *spi_busnum_to_master(u16 bus_num) 
}

EXPORT_SYMBOL_GPL(spi_busnum_to_master);



/*-------------------------------------------------------------------------*/



/* Core methods for SPI resource management */



/**

 * spi_res_alloc - allocate a spi resource that is life-cycle managed

 *                 during the processing of a spi_message while using

 *                 spi_transfer_one

 * @spi:     the spi device for which we allocate memory

 * @release: the release code to execute for this resource

 * @size:    size to alloc and return

 * @gfp:     GFP allocation flags

 *

 * Return: the pointer to the allocated data

 *

 * This may get enhanced in the future to allocate from a memory pool

 * of the @spi_device or @spi_master to avoid repeated allocations.

 */

void *spi_res_alloc(struct spi_device *spi,

		    spi_res_release_t release,

		    size_t size, gfp_t gfp)

{

	struct spi_res *sres;



	sres = kzalloc(sizeof(*sres) + size, gfp);

	if (!sres)

		return NULL;



	INIT_LIST_HEAD(&sres->entry);

	sres->release = release;



	return sres->data;

}

EXPORT_SYMBOL_GPL(spi_res_alloc);



/**

 * spi_res_free - free an spi resource

 * @res: pointer to the custom data of a resource

 *

 */

void spi_res_free(void *res)

{

	struct spi_res *sres = container_of(res, struct spi_res, data);



	if (!res)

		return;



	WARN_ON(!list_empty(&sres->entry));

	kfree(sres);

}

EXPORT_SYMBOL_GPL(spi_res_free);



/**

 * spi_res_add - add a spi_res to the spi_message

 * @message: the spi message

 * @res:     the spi_resource

 */

void spi_res_add(struct spi_message *message, void *res)

{

	struct spi_res *sres = container_of(res, struct spi_res, data);



	WARN_ON(!list_empty(&sres->entry));

	list_add_tail(&sres->entry, &message->resources);

}

EXPORT_SYMBOL_GPL(spi_res_add);



/**

 * spi_res_release - release all spi resources for this message

 * @master:  the @spi_master

 * @message: the @spi_message

 */

void spi_res_release(struct spi_master *master,

		     struct spi_message *message)

{

	struct spi_res *res;



	while (!list_empty(&message->resources)) {

		res = list_last_entry(&message->resources,

				      struct spi_res, entry);



		if (res->release)

			res->release(master, message, res->data);



		list_del(&res->entry);



		kfree(res);

	}

}

EXPORT_SYMBOL_GPL(spi_res_release);



/*-------------------------------------------------------------------------*/

include/linux/spi/spi.h

+36 −0
Original line number Diff line number Diff line
@@ -582,6 +582,37 @@ extern void spi_unregister_master(struct spi_master *master); 


extern struct spi_master *spi_busnum_to_master(u16 busnum);



/*

 * SPI resource management while processing a SPI message

 */



/**

 * struct spi_res - spi resource management structure

 * @entry:   list entry

 * @release: release code called prior to freeing this resource

 * @data:    extra data allocated for the specific use-case

 *

 * this is based on ideas from devres, but focused on life-cycle

 * management during spi_message processing

 */

typedef void (*spi_res_release_t)(struct spi_master *master,

				  struct spi_message *msg,

				  void *res);

struct spi_res {

	struct list_head        entry;

	spi_res_release_t       release;

	unsigned long long      data[]; /* guarantee ull alignment */

};



extern void *spi_res_alloc(struct spi_device *spi,

			   spi_res_release_t release,

			   size_t size, gfp_t gfp);

extern void spi_res_add(struct spi_message *message, void *res);

extern void spi_res_free(void *res);



extern void spi_res_release(struct spi_master *master,

			    struct spi_message *message);



/*---------------------------------------------------------------------------*/



/*
@@ -720,6 +751,7 @@ struct spi_transfer { 
 * @status: zero for success, else negative errno

 * @queue: for use by whichever driver currently owns the message

 * @state: for use by whichever driver currently owns the message

 * @resources: for resource management when the spi message is processed

 *

 * A @spi_message is used to execute an atomic sequence of data transfers,

 * each represented by a struct spi_transfer.  The sequence is "atomic"
@@ -766,11 +798,15 @@ struct spi_message { 
	 */

	struct list_head	queue;

	void			*state;



	/* list of spi_res reources when the spi message is processed */

	struct list_head        resources;

};



static inline void spi_message_init_no_memset(struct spi_message *m)

{

	INIT_LIST_HEAD(&m->transfers);

	INIT_LIST_HEAD(&m->resources);

}



static inline void spi_message_init(struct spi_message *m)

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