Add locking to the core iicbus(4) drivers:

- Add an sx lock to the iic(4) driver to serialize open(), close(), read(),
  and write and to protect sc_addr and sc_count in the softc.
- Use cdev->si_drv1 instead of using the minor number of the cdev to
  lookup the softc via newbus in iic(4).
- Store the device_t in the softc to avoid a similar detour via minor
  numbers in iic(4).
- Only add at most one instance of iic(4) and iicsmb(4) to each iicbus(4)
  instance, and do it in the child driver.
- Add a mutex to the iicbus(4) softc to synchronize the request/release bus
  stuff.
- Use __BUS_ACCESSOR() for IICBUS_ACCESSOR() instead of rolling our own.
- Add a mutex to the iicsmb(4) softc to protect softc state updated in the
  interrupt handler.
- Remove Giant from all the smbus methods in iicsmb(4) now that all the
  iicbus(4) backend is locked.

1 files changed, 9 insertions, 6 deletions

diff --git a/sys/dev/iicbus/iicbus.h b/sys/dev/iicbus/iicbus.h
index 55f3b93..0698d5c 100644
--- a/sys/dev/iicbus/iicbus.h
+++ b/sys/dev/iicbus/iicbus.h
@@ -29,6 +29,9 @@
 #ifndef __IICBUS_H
 #define __IICBUS_H
 
+#include <sys/_lock.h>
+#include <sys/_mutex.h>
+
 #define IICBUS_IVAR(d) (struct iicbus_ivar *) device_get_ivars(d)
 #define IICBUS_SOFTC(d) (struct iicbus_softc *) device_get_softc(d)
 
@@ -38,6 +41,7 @@ struct iicbus_softc
 	device_t owner;		/* iicbus owner device structure */
 	u_char started;		/* address of the 'started' slave
 				 * 0 if no start condition succeeded */
+	struct mtx lock;
 };
 
 struct iicbus_ivar
@@ -50,15 +54,14 @@ enum {
 };
 
 #define IICBUS_ACCESSOR(A, B, T)					\
-__inline static int							\
-iicbus_get_ ## A(device_t dev, T *t)					\
-{									\
-	return BUS_READ_IVAR(device_get_parent(dev), dev,		\
-	    IICBUS_IVAR_ ## B, (uintptr_t *) t);			\
-}
+	__BUS_ACCESSOR(iicbus, A, IICBUS, B, T)
 	
 IICBUS_ACCESSOR(addr,		ADDR,		uint32_t)
 
+#define	IICBUS_LOCK(sc)			mtx_lock(&(sc)->lock)
+#define	IICBUS_UNLOCK(sc)      		mtx_unlock(&(sc)->lock)
+#define	IICBUS_ASSERT_LOCKED(sc)       	mtx_assert(&(sc)->lock, MA_OWNED)
+
 extern int iicbus_generic_intr(device_t dev, int event, char *buf);
 
 extern driver_t iicbus_driver;