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, 15 insertions, 2 deletions

diff --git a/arch/powerpc/sysdev/fsl_rio.c b/arch/powerpc/sysdev/fsl_rio.c
index 9234be1e66f5..5011ffea4e4b 100644
--- a/arch/powerpc/sysdev/fsl_rio.c
+++ b/arch/powerpc/sysdev/fsl_rio.c
@@ -71,6 +71,8 @@
 #define RIWAR_WRTYP_ALLOC	0x00006000
 #define RIWAR_SIZE_MASK		0x0000003F
 
+static DEFINE_SPINLOCK(fsl_rio_config_lock);
+
 #define __fsl_read_rio_config(x, addr, err, op)		\
 	__asm__ __volatile__(				\
 		"1:	"op" %1,0(%2)\n"		\
@@ -184,6 +186,7 @@ fsl_rio_config_read(struct rio_mport *mport, int index, u16 destid,
 			u8 hopcount, u32 offset, int len, u32 *val)
 {
 	struct rio_priv *priv = mport->priv;
+	unsigned long flags;
 	u8 *data;
 	u32 rval, err = 0;
 
@@ -197,6 +200,8 @@ fsl_rio_config_read(struct rio_mport *mport, int index, u16 destid,
 	if (offset > (0x1000000 - len) || !IS_ALIGNED(offset, len))
 		return -EINVAL;
 
+	spin_lock_irqsave(&fsl_rio_config_lock, flags);
+
 	out_be32(&priv->maint_atmu_regs->rowtar,
 		 (destid << 22) | (hopcount << 12) | (offset >> 12));
 	out_be32(&priv->maint_atmu_regs->rowtear, (destid >> 10));
@@ -213,6 +218,7 @@ fsl_rio_config_read(struct rio_mport *mport, int index, u16 destid,
 		__fsl_read_rio_config(rval, data, err, "lwz");
 		break;
 	default:
+		spin_unlock_irqrestore(&fsl_rio_config_lock, flags);
 		return -EINVAL;
 	}
 
@@ -221,6 +227,7 @@ fsl_rio_config_read(struct rio_mport *mport, int index, u16 destid,
 			 err, destid, hopcount, offset);
 	}
 
+	spin_unlock_irqrestore(&fsl_rio_config_lock, flags);
 	*val = rval;
 
 	return err;
@@ -244,7 +251,10 @@ fsl_rio_config_write(struct rio_mport *mport, int index, u16 destid,
 			u8 hopcount, u32 offset, int len, u32 val)
 {
 	struct rio_priv *priv = mport->priv;
+	unsigned long flags;
 	u8 *data;
+	int ret = 0;
+
 	pr_debug
 		("fsl_rio_config_write:"
 		" index %d destid %d hopcount %d offset %8.8x len %d val %8.8x\n",
@@ -255,6 +265,8 @@ fsl_rio_config_write(struct rio_mport *mport, int index, u16 destid,
 	if (offset > (0x1000000 - len) || !IS_ALIGNED(offset, len))
 		return -EINVAL;
 
+	spin_lock_irqsave(&fsl_rio_config_lock, flags);
+
 	out_be32(&priv->maint_atmu_regs->rowtar,
 		 (destid << 22) | (hopcount << 12) | (offset >> 12));
 	out_be32(&priv->maint_atmu_regs->rowtear, (destid >> 10));
@@ -271,10 +283,11 @@ fsl_rio_config_write(struct rio_mport *mport, int index, u16 destid,
 		out_be32((u32 *) data, val);
 		break;
 	default:
-		return -EINVAL;
+		ret = -EINVAL;
 	}
+	spin_unlock_irqrestore(&fsl_rio_config_lock, flags);
 
-	return 0;
+	return ret;
 }
 
 static void fsl_rio_inbound_mem_init(struct rio_priv *priv)