SPI: Add helper macro for spi_driver boilerplate

This patch introduces the module_spi_driver macro which is a convenience macro
for SPI driver modules similar to module_platform_driver. It is intended to be
used by drivers which init/exit section does nothing but register/unregister
the SPI driver. By using this macro it is possible to eliminate a few lines of
boilerplate code per SPI driver.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Acked-by: Wolfram Sang <w.sang@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

include/linux/spi/spi.h

diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index bb4f5fb..176fce9 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -200,6 +200,17 @@
 		driver_unregister(&sdrv->driver);
 }
 
+/**
+ * module_spi_driver() - Helper macro for registering a SPI driver
+ * @__spi_driver: spi_driver struct
+ *
+ * Helper macro for SPI drivers which do not do anything special in module
+ * init/exit. This eliminates a lot of boilerplate. Each module may only
+ * use this macro once, and calling it replaces module_init() and module_exit()
+ */
+#define module_spi_driver(__spi_driver) \
+	module_driver(__spi_driver, spi_register_driver, \
+			spi_unregister_driver)
 
 /**
  * struct spi_master - interface to SPI master controller