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>

arch/arm/mach-omap1/flash.c

@@ -15,20 +15,12 @@
 
 void omap1_set_vpp(struct platform_device *pdev, int enable)
 {
-	static int count;
 	u32 l;
 
-	if (enable) {
-		if (count++ == 0) {
-			l = omap_readl(EMIFS_CONFIG);
-			l |= OMAP_EMIFS_CONFIG_WP;
-			omap_writel(l, EMIFS_CONFIG);
-		}
-	} else {
-		if (count && (--count == 0)) {
-			l = omap_readl(EMIFS_CONFIG);
-			l &= ~OMAP_EMIFS_CONFIG_WP;
-			omap_writel(l, EMIFS_CONFIG);
-		}
-	}
+	l = omap_readl(EMIFS_CONFIG);
+	if (enable)
+		l |= OMAP_EMIFS_CONFIG_WP;
+	else
+		l &= ~OMAP_EMIFS_CONFIG_WP;
+	omap_writel(l, EMIFS_CONFIG);
 }

arch/arm/mach-s3c2410/nor-simtec.c

@@ -35,9 +35,7 @@
 static void simtec_nor_vpp(struct platform_device *pdev, int vpp)
 {
 	unsigned int val;
-	unsigned long flags;
 
-	local_irq_save(flags);
 	val = __raw_readb(BAST_VA_CTRL3);
 
 	printk(KERN_DEBUG "%s(%d)\n", __func__, vpp);
@@ -48,7 +46,6 @@ static void simtec_nor_vpp(struct platform_device *pdev, int vpp)
 		val &= ~BAST_CPLD_CTRL3_ROMWEN;
 
 	__raw_writeb(val, BAST_VA_CTRL3);
-	local_irq_restore(flags);
 }
 
 static struct physmap_flash_data simtec_nor_pdata = {

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,