Unverified Commit 9bbbf33a authored by Mark Brown's avatar Mark Brown
Browse files

spi: gpio: Enable a single always-selected device 

Merge series from Andy Shevchenko <andriy.shevchenko@linux.intel.com>:

Enable a single always-selected device hardware setup for SPI GPIO driver,
so some custom SPI bitbang code may be replaced with the generic implementation
in the future (e.g. Up Board FPGA driver).
parents 215705db 25fac20e

drivers/spi/spi-gpio.c

+7 −38
Original line number Diff line number Diff line
@@ -39,36 +39,8 @@ struct spi_gpio { 


/*----------------------------------------------------------------------*/



/*

 * Because the overhead of going through four GPIO procedure calls

 * per transferred bit can make performance a problem, this code

 * is set up so that you can use it in either of two ways:

 *

 *   - The slow generic way:  set up platform_data to hold the GPIO

 *     numbers used for MISO/MOSI/SCK, and issue procedure calls for

 *     each of them.  This driver can handle several such busses.

 *

 *   - The quicker inlined way:  only helps with platform GPIO code

 *     that inlines operations for constant GPIOs.  This can give

 *     you tight (fast!) inner loops, but each such bus needs a

 *     new driver.  You'll define a new C file, with Makefile and

 *     Kconfig support; the C code can be a total of six lines:

 *

 *		#define DRIVER_NAME	"myboard_spi2"

 *		#define	SPI_MISO_GPIO	119

 *		#define	SPI_MOSI_GPIO	120

 *		#define	SPI_SCK_GPIO	121

 *		#define	SPI_N_CHIPSEL	4

 *		#include "spi-gpio.c"

 */



#ifndef DRIVER_NAME

#define DRIVER_NAME	"spi_gpio"



#define GENERIC_BITBANG	/* vs tight inlines */



#endif



/*----------------------------------------------------------------------*/



static inline struct spi_gpio *__pure
@@ -341,16 +313,14 @@ static int spi_gpio_probe_pdata(struct platform_device *pdev, 
	struct spi_gpio *spi_gpio = spi_controller_get_devdata(host);

	int i;



#ifdef GENERIC_BITBANG

	if (!pdata || !pdata->num_chipselect)

	if (!pdata)

		return -ENODEV;

#endif

	/*

	 * The host needs to think there is a chipselect even if not

	 * connected

	 */

	host->num_chipselect = pdata->num_chipselect ?: 1;



	/* It's just one always-selected device, fine to continue */

	if (!pdata->num_chipselect)

		return 0;



	host->num_chipselect = pdata->num_chipselect;

	spi_gpio->cs_gpios = devm_kcalloc(dev, host->num_chipselect,

					  sizeof(*spi_gpio->cs_gpios),

					  GFP_KERNEL);
@@ -445,8 +415,6 @@ static int spi_gpio_probe(struct platform_device *pdev) 
	return devm_spi_register_controller(&pdev->dev, host);

}



MODULE_ALIAS("platform:" DRIVER_NAME);



static const struct of_device_id spi_gpio_dt_ids[] = {

	{ .compatible = "spi-gpio" },

	{}
@@ -465,3 +433,4 @@ module_platform_driver(spi_gpio_driver); 
MODULE_DESCRIPTION("SPI host driver using generic bitbanged GPIO ");

MODULE_AUTHOR("David Brownell");

MODULE_LICENSE("GPL");

MODULE_ALIAS("platform:" DRIVER_NAME);