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>

diff --git a/drivers/spi/spi-bitbang.c b/drivers/spi/spi-bitbang.c
index 5ef6638..840a498 100644 (file)
--- 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;
                }