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>

1 files changed, 65 insertions, 0 deletions

diff --git a/drivers/spi/spi-cadence.c b/drivers/spi/spi-cadence.c
index 1c57ce64abba..f0b5c7b91f37 100644
--- a/drivers/spi/spi-cadence.c
+++ b/drivers/spi/spi-cadence.c
@@ -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;