mtd: maps: physmap: 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 physmap_set_vpp() calls to be nested by adding a reference
counter.

omap1_set_vpp() already used a reference counter. Since it is called from
physmap_set_vpp(), omap1_set_vpp() can now be simplified.

simtec_nor_vpp() already disabled hard interrupts. Since it is called from
physmap_set_vpp(), simtec_nor_vpp() can now be simplified.

Signed-off-by: Paul Parsons <lost.distance@yahoo.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 20 insertions, 2 deletions

diff --git a/drivers/mtd/maps/physmap.c b/drivers/mtd/maps/physmap.c
index abc562653b31..7e9233c503ab 100644
--- a/drivers/mtd/maps/physmap.c
+++ b/drivers/mtd/maps/physmap.c
@@ -27,6 +27,8 @@ struct physmap_flash_info {
         struct mtd_info         *mtd[MAX_RESOURCES];
         struct mtd_info         *cmtd;
         struct map_info         map[MAX_RESOURCES];
+        spinlock_t              vpp_lock;
+        int                     vpp_refcnt;
 };
 
 static int physmap_flash_remove(struct platform_device *dev)
@@ -63,12 +65,26 @@ static void physmap_set_vpp(struct map_info *map, int state)
 {
         struct platform_device *pdev;
         struct physmap_flash_data *physmap_data;
+        struct physmap_flash_info *info;
+        unsigned long flags;
 
         pdev = (struct platform_device *)map->map_priv_1;
         physmap_data = pdev->dev.platform_data;
 
-        if (physmap_data->set_vpp)
-                physmap_data->set_vpp(pdev, state);
+        if (!physmap_data->set_vpp)
+                return;
+
+        info = platform_get_drvdata(pdev);
+
+        spin_lock_irqsave(&info->vpp_lock, flags);
+        if (state) {
+                if (++info->vpp_refcnt == 1)    /* first nested 'on' */
+                        physmap_data->set_vpp(pdev, 1);
+        } else {
+                if (--info->vpp_refcnt == 0)    /* last nested 'off' */
+                        physmap_data->set_vpp(pdev, 0);
+        }
+        spin_unlock_irqrestore(&info->vpp_lock, flags);
 }
 
 static const char *rom_probe_types[] = {
@@ -172,6 +188,8 @@ static int physmap_flash_probe(struct platform_device *dev)
         if (err)
                 goto err_out;
 
+        spin_lock_init(&info->vpp_lock);
+
         part_types = physmap_data->part_probe_types ? : part_probe_types;
 
         mtd_device_parse_register(info->cmtd, part_types, 0,