diff options
| author | Boris Brezillon <boris.brezillon@bootlin.com> | 2018-04-26 18:18:15 +0200 |
|---|---|---|
| committer | Mark Brown <broonie@kernel.org> | 2018-05-11 11:33:15 +0900 |
| commit | b5932f5c68e5fbe74fb7a27b4d0faf919e1e1642 (patch) | |
| tree | ca5457a85c7597e715a21c9446c4aee24c0a4174 /drivers/spi | |
| parent | c36ff266dc82f4ae797a6f3513c6ffa344f7f1c7 (diff) | |
| download | linux-b5932f5c68e5fbe74fb7a27b4d0faf919e1e1642.tar.gz | |
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>
Diffstat (limited to 'drivers/spi')
| -rw-r--r-- | drivers/spi/spi.c | 33 |
1 files changed, 26 insertions, 7 deletions
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 9ab65fb2738e..c85b0cf7b4a9 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -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. + * 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->transfer && !ctlr->transfer_one && - !ctlr->transfer_one_message) + 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); |