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Unverified Commit f1ca9992 authored by Sowjanya Komatineni's avatar Sowjanya Komatineni Committed by Mark Brown
Browse files

spi: add a method for configuring CS timing 



This patch creates set_cs_timing SPI master optional method for
SPI masters to implement configuring CS timing if applicable.

This patch also creates spi_cs_timing accessory for SPI clients to
use for requesting SPI master controllers to configure device requested
CS setup time, hold time and inactive delay.

Signed-off-by: default avatarSowjanya Komatineni <skomatineni@nvidia.com>
Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent 24496da6

drivers/spi/spi.c

+15 −0
Original line number Diff line number Diff line
@@ -2995,6 +2995,21 @@ int spi_setup(struct spi_device *spi) 
}

EXPORT_SYMBOL_GPL(spi_setup);



/**

 * spi_set_cs_timing - configure CS setup, hold, and inactive delays

 * @spi: the device that requires specific CS timing configuration

 * @setup: CS setup time in terms of clock count

 * @hold: CS hold time in terms of clock count

 * @inactive_dly: CS inactive delay between transfers in terms of clock count

 */

void spi_set_cs_timing(struct spi_device *spi, u8 setup, u8 hold,

		       u8 inactive_dly)

{

	if (spi->controller->set_cs_timing)

		spi->controller->set_cs_timing(spi, setup, hold, inactive_dly);

}

EXPORT_SYMBOL_GPL(spi_set_cs_timing);



static int __spi_validate(struct spi_device *spi, struct spi_message *message)

{

	struct spi_controller *ctlr = spi->controller;

include/linux/spi/spi.h

+15 −0
Original line number Diff line number Diff line
@@ -330,6 +330,9 @@ static inline void spi_unregister_driver(struct spi_driver *sdrv) 
 *	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

 * @can_dma: determine whether this controller supports DMA
@@ -363,6 +366,7 @@ static inline void spi_unregister_driver(struct spi_driver *sdrv) 
 * @unprepare_transfer_hardware: there are currently no more messages on the

 *	queue so the subsystem notifies the driver that it may relax the

 *	hardware by issuing this call

 *

 * @set_cs: set the logic level of the chip select line.  May be called

 *          from interrupt context.

 * @prepare_message: set up the controller to transfer a single message,
@@ -488,6 +492,17 @@ struct spi_controller { 
	 */

	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() after

	 * spi_setup().

	 */

	void (*set_cs_timing)(struct spi_device *spi, u8 setup_clk_cycles,

			      u8 hold_clk_cycles, u8 inactive_clk_cycles);



	/* bidirectional bulk transfers

	 *

	 * + The transfer() method may not sleep; its main role is