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Commit b42a33bd authored by Moritz Fischer's avatar Moritz Fischer Committed by Mark Brown
Browse files

spi: cadence: Allow for GPIO pins to be used as chipselects 



This adds support for using GPIOs for chipselects as described by the
default dt-bindings.

Signed-off-by: default avatarMoritz Fischer <mdf@kernel.org>
Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent c1ae3cfa

drivers/spi/spi-cadence.c

+65 −0
Original line number Diff line number Diff line
@@ -13,6 +13,7 @@ 


#include <linux/clk.h>

#include <linux/delay.h>

#include <linux/gpio.h>

#include <linux/interrupt.h>

#include <linux/io.h>

#include <linux/module.h>
@@ -127,6 +128,10 @@ struct cdns_spi { 
	u32 is_decoded_cs;

};



struct cdns_spi_device_data {

	bool gpio_requested;

};



/* Macros for the SPI controller read/write */

static inline u32 cdns_spi_read(struct cdns_spi *xspi, u32 offset)

{
@@ -456,6 +461,64 @@ static int cdns_unprepare_transfer_hardware(struct spi_master *master) 
	return 0;

}



static int cdns_spi_setup(struct spi_device *spi)

{



	int ret = -EINVAL;

	struct cdns_spi_device_data *cdns_spi_data = spi_get_ctldata(spi);



	/* this is a pin managed by the controller, leave it alone */

	if (spi->cs_gpio == -ENOENT)

		return 0;



	/* this seems to be the first time we're here */

	if (!cdns_spi_data) {

		cdns_spi_data = kzalloc(sizeof(*cdns_spi_data), GFP_KERNEL);

		if (!cdns_spi_data)

			return -ENOMEM;

		cdns_spi_data->gpio_requested = false;

		spi_set_ctldata(spi, cdns_spi_data);

	}



	/* if we haven't done so, grab the gpio */

	if (!cdns_spi_data->gpio_requested && gpio_is_valid(spi->cs_gpio)) {

		ret = gpio_request_one(spi->cs_gpio,

				       (spi->mode & SPI_CS_HIGH) ?

				       GPIOF_OUT_INIT_LOW : GPIOF_OUT_INIT_HIGH,

				       dev_name(&spi->dev));

		if (ret)

			dev_err(&spi->dev, "can't request chipselect gpio %d\n",

				spi->cs_gpio);

		else

			cdns_spi_data->gpio_requested = true;

	} else {

		if (gpio_is_valid(spi->cs_gpio)) {

			int mode = ((spi->mode & SPI_CS_HIGH) ?

				    GPIOF_OUT_INIT_LOW : GPIOF_OUT_INIT_HIGH);



			ret = gpio_direction_output(spi->cs_gpio, mode);

			if (ret)

				dev_err(&spi->dev, "chipselect gpio %d setup failed (%d)\n",

					spi->cs_gpio, ret);

		}

	}



	return ret;

}



static void cdns_spi_cleanup(struct spi_device *spi)

{

	struct cdns_spi_device_data *cdns_spi_data = spi_get_ctldata(spi);



	if (cdns_spi_data) {

		if (cdns_spi_data->gpio_requested)

			gpio_free(spi->cs_gpio);

		kfree(cdns_spi_data);

		spi_set_ctldata(spi, NULL);

	}



}



/**

 * cdns_spi_probe - Probe method for the SPI driver

 * @pdev:	Pointer to the platform_device structure
@@ -555,6 +618,8 @@ static int cdns_spi_probe(struct platform_device *pdev) 
	master->transfer_one = cdns_transfer_one;

	master->unprepare_transfer_hardware = cdns_unprepare_transfer_hardware;

	master->set_cs = cdns_spi_chipselect;

	master->setup = cdns_spi_setup;

	master->cleanup = cdns_spi_cleanup;

	master->auto_runtime_pm = true;

	master->mode_bits = SPI_CPOL | SPI_CPHA;