mtd: maps: pcmciamtd: Add reference counter to set_vpp()

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Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=7c8d206f219fe52966d970f791246a542718e5ba
Commit:     7c8d206f219fe52966d970f791246a542718e5ba
Parent:     5fbabf3f45a15c2b39170980cee01368138f4d79
Author:     Paul Parsons <lost.distance at yahoo.com>
AuthorDate: Wed Mar 7 14:13:41 2012 +0000
Committer:  David Woodhouse <David.Woodhouse at intel.com>
CommitDate: Tue Mar 27 00:52:56 2012 +0100

    mtd: maps: pcmciamtd: Add reference counter to set_vpp()
    
    This patch is part of a set which fixes unnecessary flash erase and write errors
    resulting from the MTD CFI driver turning off vpp while an erase is in progress.
    This patch allows pcmciamtd_set_vpp() calls to be nested by adding a reference
    counter.
    
    Signed-off-by: Paul Parsons <lost.distance at yahoo.com>
    Signed-off-by: Artem Bityutskiy <artem.bityutskiy at linux.intel.com>
    Signed-off-by: David Woodhouse <David.Woodhouse at intel.com>
---
 drivers/mtd/maps/pcmciamtd.c |   13 ++++++++++++-
 1 files changed, 12 insertions(+), 1 deletions(-)

diff --git a/drivers/mtd/maps/pcmciamtd.c b/drivers/mtd/maps/pcmciamtd.c
index e8e9fec..7d5cf36 100644
--- a/drivers/mtd/maps/pcmciamtd.c
+++ b/drivers/mtd/maps/pcmciamtd.c
@@ -295,13 +295,24 @@ static void pcmcia_copy_to(struct map_info *map, unsigned long to, const void *f
 }
 
 
+static DEFINE_SPINLOCK(pcmcia_vpp_lock);
+static int pcmcia_vpp_refcnt;
 static void pcmciamtd_set_vpp(struct map_info *map, int on)
 {
 	struct pcmciamtd_dev *dev = (struct pcmciamtd_dev *)map->map_priv_1;
 	struct pcmcia_device *link = dev->p_dev;
+	unsigned long flags;
 
 	pr_debug("dev = %p on = %d vpp = %d\n\n", dev, on, dev->vpp);
-	pcmcia_fixup_vpp(link, on ? dev->vpp : 0);
+	spin_lock_irqsave(&pcmcia_vpp_lock, flags);
+	if (on) {
+		if (++pcmcia_vpp_refcnt == 1)   /* first nested 'on' */
+			pcmcia_fixup_vpp(link, dev->vpp);
+	} else {
+		if (--pcmcia_vpp_refcnt == 0)   /* last nested 'off' */
+			pcmcia_fixup_vpp(link, 0);
+	}
+	spin_unlock_irqrestore(&pcmcia_vpp_lock, flags);
 }