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>

2 files changed, 12 insertions, 35 deletions

diff --git a/drivers/rapidio/devices/tsi721.c b/drivers/rapidio/devices/tsi721.c
index 315a4be8dc1e..9a68914100ad 100644
--- a/drivers/rapidio/devices/tsi721.c
+++ b/drivers/rapidio/devices/tsi721.c
@@ -51,6 +51,8 @@ module_param(mbox_sel, byte, S_IRUGO);
 MODULE_PARM_DESC(mbox_sel,
 		 "RIO Messaging MBOX Selection Mask (default: 0x0f = all)");
 
+static DEFINE_SPINLOCK(tsi721_maint_lock);
+
 static void tsi721_omsg_handler(struct tsi721_device *priv, int ch);
 static void tsi721_imsg_handler(struct tsi721_device *priv, int ch);
 
@@ -124,12 +126,15 @@ static int tsi721_maint_dma(struct tsi721_device *priv, u32 sys_size,
 	void __iomem *regs = priv->regs + TSI721_DMAC_BASE(priv->mdma.ch_id);
 	struct tsi721_dma_desc *bd_ptr;
 	u32 rd_count, swr_ptr, ch_stat;
+	unsigned long flags;
 	int i, err = 0;
 	u32 op = do_wr ? MAINT_WR : MAINT_RD;
 
 	if (offset > (RIO_MAINT_SPACE_SZ - len) || (len != sizeof(u32)))
 		return -EINVAL;
 
+	spin_lock_irqsave(&tsi721_maint_lock, flags);
+
 	bd_ptr = priv->mdma.bd_base;
 
 	rd_count = ioread32(regs + TSI721_DMAC_DRDCNT);
@@ -197,7 +202,9 @@ static int tsi721_maint_dma(struct tsi721_device *priv, u32 sys_size,
 	 */
 	swr_ptr = ioread32(regs + TSI721_DMAC_DSWP);
 	iowrite32(swr_ptr, regs + TSI721_DMAC_DSRP);
+
 err_out:
+	spin_unlock_irqrestore(&tsi721_maint_lock, flags);
 
 	return err;
 }
diff --git a/drivers/rapidio/rio-access.c b/drivers/rapidio/rio-access.c
index a3824baca2e5..3ee9af83b638 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);