spi: bitbang: Make setup_transfer() callback optional

Some controller drivers have no need of this callback (spi-altera even
causes a NULL pointer dereference because it doesn't register the callback,
falsely assuming that it is already optional).

Fixes: 30af9b558a56 ("spi/bitbang: Drop empty setup() functions")
Signed-off-by: Pelle Nilsson <per.nilsson@xelmo.com>
Reviewed-by: Ezequiel Garcia <ezequiel.garcia@vanguardiasur.com.ar>
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 10 insertions, 7 deletions

diff --git a/drivers/spi/spi-bitbang.c b/drivers/spi/spi-bitbang.c
index 5ef6638d5e8a..840a4984d365 100644
--- a/drivers/spi/spi-bitbang.c
+++ b/drivers/spi/spi-bitbang.c
@@ -180,7 +180,6 @@ int spi_bitbang_setup(struct spi_device *spi)
 {
         struct spi_bitbang_cs   *cs = spi->controller_state;
         struct spi_bitbang      *bitbang;
-        int                     retval;
         unsigned long           flags;
 
         bitbang = spi_master_get_devdata(spi->master);
@@ -197,9 +196,11 @@ int spi_bitbang_setup(struct spi_device *spi)
         if (!cs->txrx_word)
                 return -EINVAL;
 
-        retval = bitbang->setup_transfer(spi, NULL);
-        if (retval < 0)
-                return retval;
+        if (bitbang->setup_transfer) {
+                int retval = bitbang->setup_transfer(spi, NULL);
+                if (retval < 0)
+                        return retval;
+        }
 
         dev_dbg(&spi->dev, "%s, %u nsec/bit\n", __func__, 2 * cs->nsecs);
 
@@ -295,9 +296,11 @@ static int spi_bitbang_transfer_one(struct spi_master *master,
 
                 /* init (-1) or override (1) transfer params */
                 if (do_setup != 0) {
-                        status = bitbang->setup_transfer(spi, t);
-                        if (status < 0)
-                                break;
+                        if (bitbang->setup_transfer) {
+                                status = bitbang->setup_transfer(spi, t);
+                                if (status < 0)
+                                        break;
+                        }
                         if (do_setup == -1)
                                 do_setup = 0;
                 }