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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: Moritz Fischer <mdf@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Moritz Fischer 2017-04-25 11:30:14 -07:00 committed by Mark Brown
parent c1ae3cfa0e
commit b42a33bd93
1 changed files with 65 additions and 0 deletions
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65
drivers/spi/spi-cadence.c
View File

@ -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;