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: Martin Sperl <kernel@martin.sperl.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Martin Sperl 2015-12-14 15:20:19 +00:00 committed by Mark Brown
parent d780c3711d
commit 523baf5a06
2 changed files with 177 additions and 0 deletions

View File

@ -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.
*/

View File

@ -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.