spi: Make spi_alloc_device and spi_add_device public again

This functions were previously made private since they
were not used. However, these functions will be needed
again.

Partial revert of commit da21fde0
("spi: Make several public functions private to spi.c")
Signed-off-by: Stefan Binding <sbinding@opensource.cirrus.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20220121172431.6876-2-sbinding@opensource.cirrus.comSigned-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi.c

@@ -532,7 +532,7 @@ static DEFINE_MUTEX(board_lock);
  *
  * Return: a pointer to the new device, or NULL.
  */
-static struct spi_device *spi_alloc_device(struct spi_controller *ctlr)
+struct spi_device *spi_alloc_device(struct spi_controller *ctlr)
 {
 	struct spi_device	*spi;
 
@@ -557,6 +557,7 @@ static struct spi_device *spi_alloc_device(struct spi_controller *ctlr)
 	device_initialize(&spi->dev);
 	return spi;
 }
+EXPORT_SYMBOL_GPL(spi_alloc_device);
 
 static void spi_dev_set_name(struct spi_device *spi)
 {
@@ -652,7 +653,7 @@ static int __spi_add_device(struct spi_device *spi)
  *
  * Return: 0 on success; negative errno on failure
  */
-static int spi_add_device(struct spi_device *spi)
+int spi_add_device(struct spi_device *spi)
 {
 	struct spi_controller *ctlr = spi->controller;
 	struct device *dev = ctlr->dev.parent;
@@ -673,6 +674,7 @@ static int spi_add_device(struct spi_device *spi)
 	mutex_unlock(&ctlr->add_lock);
 	return status;
 }
+EXPORT_SYMBOL_GPL(spi_add_device);
 
 static int spi_add_device_locked(struct spi_device *spi)
 {

include/linux/spi/spi.h

@@ -1452,7 +1452,19 @@ spi_register_board_info(struct spi_board_info const *info, unsigned n)
  * use spi_new_device() to describe each device.  You can also call
  * spi_unregister_device() to start making that device vanish, but
  * normally that would be handled by spi_unregister_controller().
+ *
+ * You can also use spi_alloc_device() and spi_add_device() to use a two
+ * stage registration sequence for each spi_device. This gives the caller
+ * some more control over the spi_device structure before it is registered,
+ * but requires that caller to initialize fields that would otherwise
+ * be defined using the board info.
  */
+extern struct spi_device *
+spi_alloc_device(struct spi_controller *ctlr);
+
+extern int
+spi_add_device(struct spi_device *spi);
+
 extern struct spi_device *
 spi_new_device(struct spi_controller *, struct spi_board_info *);