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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: Boris Brezillon <boris.brezillon@bootlin.com> Reviewed-by: Frieder Schrempf <frieder.schrempf@exceet.de> Tested-by: Frieder Schrempf <frieder.schrempf@exceet.de> Signed-off-by: Mark Brown <broonie@kernel.org>
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1 changed files with 26 additions and 7 deletions
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@ -28,6 +28,7 @@
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#include <linux/slab.h>
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#include <linux/mod_devicetable.h>
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#include <linux/spi/spi.h>
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#include <linux/spi/spi-mem.h>
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#include <linux/of_gpio.h>
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#include <linux/pm_runtime.h>
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#include <linux/pm_domain.h>
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@ -2071,12 +2072,19 @@ static int of_spi_register_master(struct spi_controller *ctlr)
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static int spi_controller_check_ops(struct spi_controller *ctlr)
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{
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/*
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* The controller must at least implement one of the ->transfer()
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* hooks.
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* The controller may implement only the high-level SPI-memory like
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* operations if it does not support regular SPI transfers, and this is
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* valid use case.
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* If ->mem_ops is NULL, we request that at least one of the
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* ->transfer_xxx() method be implemented.
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*/
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if (!ctlr->transfer && !ctlr->transfer_one &&
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!ctlr->transfer_one_message)
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if (ctlr->mem_ops) {
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if (!ctlr->mem_ops->exec_op)
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return -EINVAL;
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} else if (!ctlr->transfer && !ctlr->transfer_one &&
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!ctlr->transfer_one_message) {
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return -EINVAL;
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}
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return 0;
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}
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@ -2187,10 +2195,14 @@ int spi_register_controller(struct spi_controller *ctlr)
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spi_controller_is_slave(ctlr) ? "slave" : "master",
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dev_name(&ctlr->dev));
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/* If we're using a queued driver, start the queue */
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if (ctlr->transfer)
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/*
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* If we're using a queued driver, start the queue. Note that we don't
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* need the queueing logic if the driver is only supporting high-level
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* memory operations.
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*/
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if (ctlr->transfer) {
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dev_info(dev, "controller is unqueued, this is deprecated\n");
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else {
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} else if (ctlr->transfer_one || ctlr->transfer_one_message) {
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status = spi_controller_initialize_queue(ctlr);
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if (status) {
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device_del(&ctlr->dev);
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@ -2920,6 +2932,13 @@ static int __spi_async(struct spi_device *spi, struct spi_message *message)
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{
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struct spi_controller *ctlr = spi->controller;
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/*
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* Some controllers do not support doing regular SPI transfers. Return
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* ENOTSUPP when this is the case.
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*/
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if (!ctlr->transfer)
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return -ENOTSUPP;
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message->spi = spi;
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SPI_STATISTICS_INCREMENT_FIELD(&ctlr->statistics, spi_async);
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