Unverified Commit b5932f5c authored by Boris Brezillon's avatar Boris Brezillon Committed by Mark Brown
Browse files

spi: Make support for regular transfers optional when ->mem_ops != NULL 



Some SPI/QuadSPI controllers only expose a high-level SPI memory
interface, thus preventing any regular SPI transfers from being done.

In that case, SPI controller drivers can leave all ->transfer_xxx()
hooks empty and only implement the spi_mem_ops interface.

Adjust the core to allow such situations:
- extend spi_controller_check_ops() to accept situations where all
  ->transfer_xxx() pointers are NULL only if ->mem_ops != NULL
- make sure we do not initialize the SPI message queue if
  ctlr->transfer_one and ctlr->transfer_one_message are missing
- return -ENOTSUPP if someone tries to do a regular SPI transfer on
  a controller that does not support it

Signed-off-by: default avatarBoris Brezillon <boris.brezillon@bootlin.com>
Reviewed-by: default avatarFrieder Schrempf <frieder.schrempf@exceet.de>
Tested-by: default avatarFrieder Schrempf <frieder.schrempf@exceet.de>
Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent c36ff266

drivers/spi/spi.c

+26 −7
Original line number Diff line number Diff line
@@ -28,6 +28,7 @@ 
#include <linux/slab.h>

#include <linux/mod_devicetable.h>

#include <linux/spi/spi.h>

#include <linux/spi/spi-mem.h>

#include <linux/of_gpio.h>

#include <linux/pm_runtime.h>

#include <linux/pm_domain.h>
@@ -2071,12 +2072,19 @@ static int of_spi_register_master(struct spi_controller *ctlr) 
static int spi_controller_check_ops(struct spi_controller *ctlr)

{

	/*

	 * The controller must at least implement one of the ->transfer()

	 * hooks.

	 */

	if (!ctlr->transfer && !ctlr->transfer_one &&

	    !ctlr->transfer_one_message)

	 * The controller may implement only the high-level SPI-memory like

	 * operations if it does not support regular SPI transfers, and this is

	 * valid use case.

	 * If ->mem_ops is NULL, we request that at least one of the

	 * ->transfer_xxx() method be implemented.

	 */

	if (ctlr->mem_ops) {

		if (!ctlr->mem_ops->exec_op)

			return -EINVAL;

	} else if (!ctlr->transfer && !ctlr->transfer_one &&

		   !ctlr->transfer_one_message) {

		return -EINVAL;

	}



	return 0;

}
@@ -2187,10 +2195,14 @@ int spi_register_controller(struct spi_controller *ctlr) 
			spi_controller_is_slave(ctlr) ? "slave" : "master",

			dev_name(&ctlr->dev));



	/* If we're using a queued driver, start the queue */

	if (ctlr->transfer)

	/*

	 * If we're using a queued driver, start the queue. Note that we don't

	 * need the queueing logic if the driver is only supporting high-level

	 * memory operations.

	 */

	if (ctlr->transfer) {

		dev_info(dev, "controller is unqueued, this is deprecated\n");

	else {

	} else if (ctlr->transfer_one || ctlr->transfer_one_message) {

		status = spi_controller_initialize_queue(ctlr);

		if (status) {

			device_del(&ctlr->dev);
@@ -2920,6 +2932,13 @@ static int __spi_async(struct spi_device *spi, struct spi_message *message) 
{

	struct spi_controller *ctlr = spi->controller;



	/*

	 * Some controllers do not support doing regular SPI transfers. Return

	 * ENOTSUPP when this is the case.

	 */

	if (!ctlr->transfer)

		return -ENOTSUPP;



	message->spi = spi;



	SPI_STATISTICS_INCREMENT_FIELD(&ctlr->statistics, spi_async);

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