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Commit 523baf5a authored by Martin Sperl's avatar Martin Sperl Committed by Mark Brown
Browse files

spi: core: add spi_replace_transfers method 



Add the spi_replace_transfers method that can get used
to replace some spi_transfers from a spi_message with other
transfers.

Signed-off-by: default avatarMartin Sperl <kernel@martin.sperl.org>
Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent d780c371

drivers/spi/spi.c

+132 −0
Original line number Diff line number Diff line
@@ -2107,6 +2107,138 @@ EXPORT_SYMBOL_GPL(spi_res_release); 


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



/* Core methods for spi_message alterations */



static void __spi_replace_transfers_release(struct spi_master *master,

					    struct spi_message *msg,

					    void *res)

{

	struct spi_replaced_transfers *rxfer = res;

	size_t i;



	/* call extra callback if requested */

	if (rxfer->release)

		rxfer->release(master, msg, res);



	/* insert replaced transfers back into the message */

	list_splice(&rxfer->replaced_transfers, rxfer->replaced_after);



	/* remove the formerly inserted entries */

	for (i = 0; i < rxfer->inserted; i++)

		list_del(&rxfer->inserted_transfers[i].transfer_list);

}



/**

 * spi_replace_transfers - replace transfers with several transfers

 *                         and register change with spi_message.resources

 * @msg:           the spi_message we work upon

 * @xfer_first:    the first spi_transfer we want to replace

 * @remove:        number of transfers to remove

 * @insert:        the number of transfers we want to insert instead

 * @release:       extra release code necessary in some circumstances

 * @extradatasize: extra data to allocate (with alignment guarantees

 *                 of struct @spi_transfer)

 *

 * Returns: pointer to @spi_replaced_transfers,

 *          PTR_ERR(...) in case of errors.

 */

struct spi_replaced_transfers *spi_replace_transfers(

	struct spi_message *msg,

	struct spi_transfer *xfer_first,

	size_t remove,

	size_t insert,

	spi_replaced_release_t release,

	size_t extradatasize,

	gfp_t gfp)

{

	struct spi_replaced_transfers *rxfer;

	struct spi_transfer *xfer;

	size_t i;



	/* allocate the structure using spi_res */

	rxfer = spi_res_alloc(msg->spi, __spi_replace_transfers_release,

			      insert * sizeof(struct spi_transfer)

			      + sizeof(struct spi_replaced_transfers)

			      + extradatasize,

			      gfp);

	if (!rxfer)

		return ERR_PTR(-ENOMEM);



	/* the release code to invoke before running the generic release */

	rxfer->release = release;



	/* assign extradata */

	if (extradatasize)

		rxfer->extradata =

			&rxfer->inserted_transfers[insert];



	/* init the replaced_transfers list */

	INIT_LIST_HEAD(&rxfer->replaced_transfers);



	/* assign the list_entry after which we should reinsert

	 * the @replaced_transfers - it may be spi_message.messages!

	 */

	rxfer->replaced_after = xfer_first->transfer_list.prev;



	/* remove the requested number of transfers */

	for (i = 0; i < remove; i++) {

		/* if the entry after replaced_after it is msg->transfers

		 * then we have been requested to remove more transfers

		 * than are in the list

		 */

		if (rxfer->replaced_after->next == &msg->transfers) {

			dev_err(&msg->spi->dev,

				"requested to remove more spi_transfers than are available\n");

			/* insert replaced transfers back into the message */

			list_splice(&rxfer->replaced_transfers,

				    rxfer->replaced_after);



			/* free the spi_replace_transfer structure */

			spi_res_free(rxfer);



			/* and return with an error */

			return ERR_PTR(-EINVAL);

		}



		/* remove the entry after replaced_after from list of

		 * transfers and add it to list of replaced_transfers

		 */

		list_move_tail(rxfer->replaced_after->next,

			       &rxfer->replaced_transfers);

	}



	/* create copy of the given xfer with identical settings

	 * based on the first transfer to get removed

	 */

	for (i = 0; i < insert; i++) {

		/* we need to run in reverse order */

		xfer = &rxfer->inserted_transfers[insert - 1 - i];



		/* copy all spi_transfer data */

		memcpy(xfer, xfer_first, sizeof(*xfer));



		/* add to list */

		list_add(&xfer->transfer_list, rxfer->replaced_after);



		/* clear cs_change and delay_usecs for all but the last */

		if (i) {

			xfer->cs_change = false;

			xfer->delay_usecs = 0;

		}

	}



	/* set up inserted */

	rxfer->inserted = insert;



	/* and register it with spi_res/spi_message */

	spi_res_add(msg, rxfer);



	return rxfer;

}

EXPORT_SYMBOL_GPL(spi_replace_transfers);



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



/* Core methods for SPI master protocol drivers.  Some of the

 * other core methods are currently defined as inline functions.

 */

include/linux/spi/spi.h

+45 −0
Original line number Diff line number Diff line
@@ -890,6 +890,51 @@ spi_max_transfer_size(struct spi_device *spi) 


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



/* SPI transfer replacement methods which make use of spi_res */



/**

 * struct spi_replaced_transfers - structure describing the spi_transfer

 *                                 replacements that have occurred

 *                                 so that they can get reverted

 * @release:            some extra release code to get executed prior to

 *                      relasing this structure

 * @extradata:          pointer to some extra data if requested or NULL

 * @replaced_transfers: transfers that have been replaced and which need

 *                      to get restored

 * @replaced_after:     the transfer after which the @replaced_transfers

 *                      are to get re-inserted

 * @inserted:           number of transfers inserted

 * @inserted_transfers: array of spi_transfers of array-size @inserted,

 *                      that have been replacing replaced_transfers

 *

 * note: that @extradata will point to @inserted_transfers[@inserted]

 * if some extra allocation is requested, so alignment will be the same

 * as for spi_transfers

 */

struct spi_replaced_transfers;

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

				       struct spi_message *msg,

				       struct spi_replaced_transfers *res);

struct spi_replaced_transfers {

	spi_replaced_release_t release;

	void *extradata;

	struct list_head replaced_transfers;

	struct list_head *replaced_after;

	size_t inserted;

	struct spi_transfer inserted_transfers[];

};



extern struct spi_replaced_transfers *spi_replace_transfers(

	struct spi_message *msg,

	struct spi_transfer *xfer_first,

	size_t remove,

	size_t insert,

	spi_replaced_release_t release,

	size_t extradatasize,

	gfp_t gfp);



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



/* All these synchronous SPI transfer routines are utilities layered

 * over the core async transfer primitive.  Here, "synchronous" means

 * they will sleep uninterruptibly until the async transfer completes.