[PATCH v2 10/12] spi: add support for spi_controller::set_cs_timing

[Marco Felsch <m.felsch@pengutronix.de>]

Import the spi_controller set_cs_timing() hook to make it easier to port
Linux spi drivers.

Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
---
Changelog:
v2:
 - add spi_set_cs_timing()

 drivers/spi/spi.c | 20 ++++++++++++++++++++
 include/spi/spi.h | 12 ++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 78569301776f..425c35759045 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -34,6 +34,22 @@ struct boardinfo {
 static LIST_HEAD(board_list);
 static LIST_HEAD(spi_controller_list);
 
+/**
+ * spi_set_cs_timing - configure CS setup, hold, and inactive delays
+ * @spi: the device that requires specific CS timing configuration
+ *
+ * Return: zero on success, else a negative error code.
+ */
+static int spi_set_cs_timing(struct spi_device *spi)
+{
+	int status = 0;
+
+	if (spi->controller->set_cs_timing && !spi->cs_gpiod)
+		status = spi->controller->set_cs_timing(spi);
+
+	return status;
+}
+
 /**
  * spi_new_device - instantiate one new SPI device
  * @master: Controller to which device is connected
@@ -101,6 +117,10 @@ struct spi_device *spi_new_device(struct spi_controller *ctrl,
 		goto fail;
 	}
 
+	status = spi_set_cs_timing(proxy);
+	if (status)
+		goto fail;
+
 	status = register_device(&proxy->dev);
 	if (status)
 		goto fail;
diff --git a/include/spi/spi.h b/include/spi/spi.h
index a8bbf55e0a5a..106cca664068 100644
--- a/include/spi/spi.h
+++ b/include/spi/spi.h
@@ -179,6 +179,9 @@ static inline void spi_set_ctldata(struct spi_device *spi, void *state)
  *	must fail if an unrecognized or unsupported mode is requested.
  *	It's always safe to call this unless transfers are pending on
  *	the device whose settings are being modified.
+ * @set_cs_timing: optional hook for SPI devices to request SPI master
+ * controller for configuring specific CS setup time, hold time and inactive
+ * delay interms of clock counts
  * @transfer: adds a message to the controller's transfer queue.
  * @cleanup: frees controller-specific state
  * @cs_gpiods: Array of GPIO descriptors to use as chip select lines; one per CS
@@ -249,6 +252,15 @@ struct spi_controller {
 	/* setup mode and clock, etc (spi driver may call many times) */
 	int			(*setup)(struct spi_device *spi);
 
+	/*
+	 * set_cs_timing() method is for SPI controllers that supports
+	 * configuring CS timing.
+	 *
+	 * This hook allows SPI client drivers to request SPI controllers
+	 * to configure specific CS timing through spi_set_cs_timing().
+	 */
+	int (*set_cs_timing)(struct spi_device *spi);
+
 	/* bidirectional bulk transfers
 	 *
 	 * + The transfer() method may not sleep; its main role is
-- 
2.39.5