[patch 19/51] rapidio: remove global irq spinlocks from the subsystem

[patch 19/51] rapidio: remove global irq spinlocks from the subsystem

[akpm]

From: Ioan Nicu <ioan.nicu.ext@nokia.com>
Subject: 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>
---

 arch/powerpc/sysdev/fsl_rio.c    |   17 ++++++++++--
 arch/powerpc/sysdev/fsl_rmu.c    |    8 +++++
 drivers/rapidio/devices/tsi721.c |    7 +++++
 drivers/rapidio/rio-access.c     |   40 +++--------------------------
 4 files changed, 35 insertions(+), 37 deletions(-)

diff -puN arch/powerpc/sysdev/fsl_rio.c~rapidio-remove-global-irq-spinlocks-from-the-subsystem arch/powerpc/sysdev/fsl_rio.c
--- a/arch/powerpc/sysdev/fsl_rio.c~rapidio-remove-global-irq-spinlocks-from-the-subsystem
+++ a/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 *mp
 			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 *mp
 	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 *mp
 		__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 *mp
 			 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 *m
 			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 *m
 	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 *m
 		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)
diff -puN arch/powerpc/sysdev/fsl_rmu.c~rapidio-remove-global-irq-spinlocks-from-the-subsystem arch/powerpc/sysdev/fsl_rmu.c
--- a/arch/powerpc/sysdev/fsl_rmu.c~rapidio-remove-global-irq-spinlocks-from-the-subsystem
+++ a/arch/powerpc/sysdev/fsl_rmu.c
@@ -104,6 +104,8 @@
 
 #define DOORBELL_MESSAGE_SIZE	0x08
 
+static DEFINE_SPINLOCK(fsl_rio_doorbell_lock);
+
 struct rio_msg_regs {
 	u32 omr;
 	u32 osr;
@@ -626,9 +628,13 @@ err_out:
 int fsl_rio_doorbell_send(struct rio_mport *mport,
 				int index, u16 destid, u16 data)
 {
+	unsigned long flags;
+
 	pr_debug("fsl_doorbell_send: index %d destid %4.4x data %4.4x\n",
 		 index, destid, data);
 
+	spin_lock_irqsave(&fsl_rio_doorbell_lock, flags);
+
 	/* In the serial version silicons, such as MPC8548, MPC8641,
 	 * below operations is must be.
 	 */
@@ -638,6 +644,8 @@ int fsl_rio_doorbell_send(struct rio_mpo
 	out_be32(&dbell->dbell_regs->oddatr, (index << 20) | data);
 	out_be32(&dbell->dbell_regs->odmr, 0x00000001);
 
+	spin_unlock_irqrestore(&fsl_rio_doorbell_lock, flags);
+
 	return 0;
 }
 
diff -puN drivers/rapidio/devices/tsi721.c~rapidio-remove-global-irq-spinlocks-from-the-subsystem drivers/rapidio/devices/tsi721.c
--- a/drivers/rapidio/devices/tsi721.c~rapidio-remove-global-irq-spinlocks-from-the-subsystem
+++ a/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 tsi72
 	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 tsi72
 	 */
 	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 -puN drivers/rapidio/rio-access.c~rapidio-remove-global-irq-spinlocks-from-the-subsystem drivers/rapidio/rio-access.c
--- a/drivers/rapidio/rio-access.c~rapidio-remove-global-irq-spinlocks-from-the-subsystem
+++ a/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
  */
 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);