rapidio: remove global irq spinlocks from the subsystem

Locking of config and doorbell operations should be done only if the
underlying hardware requires it.

This patch removes the global spinlocks from the rapidio subsystem and
moves them to the mport drivers (fsl_rio and tsi721), only to the
necessary places.  For example, local config space read and write
operations (lcread/lcwrite) are atomic in all existing drivers, so there
should be no need for locking, while the cread/cwrite operations which
generate maintenance transactions need to be synchronized with a lock.

Later, each driver could chose to use a per-port lock instead of a
global one, or even more granular locking.

Link: http://lkml.kernel.org/r/20170824113023.GD50104@nokia.com
Signed-off-by: Ioan Nicu <ioan.nicu.ext@nokia.com>
Signed-off-by: Frank Kunz <frank.kunz@nokia.com>
Acked-by: Alexandre Bounine <alexandre.bounine@idt.com>
Cc: Matt Porter <mporter@kernel.crashing.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 5 insertions, 35 deletions

diff --git a/drivers/rapidio/rio-access.c b/drivers/rapidio/rio-access.c
index a3824ba..3ee9af8 100644
--- a/drivers/rapidio/rio-access.c
+++ b/drivers/rapidio/rio-access.c
@@ -14,16 +14,8 @@
 #include <linux/module.h>
 
 /*
- * These interrupt-safe spinlocks protect all accesses to RIO
- * configuration space and doorbell access.
- */
-static DEFINE_SPINLOCK(rio_config_lock);
-static DEFINE_SPINLOCK(rio_doorbell_lock);
-
-/*
  *  Wrappers for all RIO configuration access functions.  They just check
- *  alignment, do locking and call the low-level functions pointed to
- *  by rio_mport->ops.
+ *  alignment and call the low-level functions pointed to by rio_mport->ops.
  */
 
 #define RIO_8_BAD 0
@@ -44,13 +36,10 @@ int __rio_local_read_config_##size \
 	(struct rio_mport *mport, u32 offset, type *value)		\
 {									\
 	int res;							\
-	unsigned long flags;						\
 	u32 data = 0;							\
 	if (RIO_##size##_BAD) return RIO_BAD_SIZE;			\
-	spin_lock_irqsave(&rio_config_lock, flags);			\
 	res = mport->ops->lcread(mport, mport->id, offset, len, &data);	\
 	*value = (type)data;						\
-	spin_unlock_irqrestore(&rio_config_lock, flags);		\
 	return res;							\
 }
 
@@ -67,13 +56,8 @@ int __rio_local_read_config_##size \
 int __rio_local_write_config_##size \
 	(struct rio_mport *mport, u32 offset, type value)		\
 {									\
-	int res;							\
-	unsigned long flags;						\
 	if (RIO_##size##_BAD) return RIO_BAD_SIZE;			\
-	spin_lock_irqsave(&rio_config_lock, flags);			\
-	res = mport->ops->lcwrite(mport, mport->id, offset, len, value);\
-	spin_unlock_irqrestore(&rio_config_lock, flags);		\
-	return res;							\
+	return mport->ops->lcwrite(mport, mport->id, offset, len, value);\
 }
 
 RIO_LOP_READ(8, u8, 1)
@@ -104,13 +88,10 @@ int rio_mport_read_config_##size \
 	(struct rio_mport *mport, u16 destid, u8 hopcount, u32 offset, type *value)	\
 {									\
 	int res;							\
-	unsigned long flags;						\
 	u32 data = 0;							\
 	if (RIO_##size##_BAD) return RIO_BAD_SIZE;			\
-	spin_lock_irqsave(&rio_config_lock, flags);			\
 	res = mport->ops->cread(mport, mport->id, destid, hopcount, offset, len, &data); \
 	*value = (type)data;						\
-	spin_unlock_irqrestore(&rio_config_lock, flags);		\
 	return res;							\
 }
 
@@ -127,13 +108,9 @@ int rio_mport_read_config_##size \
 int rio_mport_write_config_##size \
 	(struct rio_mport *mport, u16 destid, u8 hopcount, u32 offset, type value)	\
 {									\
-	int res;							\
-	unsigned long flags;						\
 	if (RIO_##size##_BAD) return RIO_BAD_SIZE;			\
-	spin_lock_irqsave(&rio_config_lock, flags);			\
-	res = mport->ops->cwrite(mport, mport->id, destid, hopcount, offset, len, value); \
-	spin_unlock_irqrestore(&rio_config_lock, flags);		\
-	return res;							\
+	return mport->ops->cwrite(mport, mport->id, destid, hopcount,	\
+			offset, len, value);				\
 }
 
 RIO_OP_READ(8, u8, 1)
@@ -162,14 +139,7 @@ EXPORT_SYMBOL_GPL(rio_mport_write_config_32);
  */
 int rio_mport_send_doorbell(struct rio_mport *mport, u16 destid, u16 data)
 {
-	int res;
-	unsigned long flags;
-
-	spin_lock_irqsave(&rio_doorbell_lock, flags);
-	res = mport->ops->dsend(mport, mport->id, destid, data);
-	spin_unlock_irqrestore(&rio_doorbell_lock, flags);
-
-	return res;
+	return mport->ops->dsend(mport, mport->id, destid, data);
 }
 
 EXPORT_SYMBOL_GPL(rio_mport_send_doorbell);