[PATCH] SPI: busnum == 0 needs to work
We need to be able to have a "SPI bus 0" matching chip numbering; but
that number was wrongly used to flag dynamic allocation of a bus number.
This patch resolves that issue; now negative numbers trigger dynamic alloc.
It also updates the how-to-write-a-controller-driver overview to mention
this stuff.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index 77add90..e928c0d 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -172,13 +172,13 @@
struct spi_master {
struct class_device cdev;
- /* other than zero (== assign one dynamically), bus_num is fully
+ /* other than negative (== assign one dynamically), bus_num is fully
* board-specific. usually that simplifies to being SOC-specific.
- * example: one SOC has three SPI controllers, numbered 1..3,
+ * example: one SOC has three SPI controllers, numbered 0..2,
* and one board's schematics might show it using SPI-2. software
* would normally use bus_num=2 for that controller.
*/
- u16 bus_num;
+ s16 bus_num;
/* chipselects will be integral to many controllers; some others
* might use board-specific GPIOs.