sony-laptop: Prepare the platform driver for multiple users.

Both the SNC and SPIC device drivers will create attributes and thus
there's the need to have an internal usage count to avoid
re-registering or de-registering at the wrong time.
Signed-off-by: Mattia Dongili <malattia@linux.it>
Signed-off-by: Len Brown <len.brown@intel.com>

drivers/misc/sony-laptop.c

@@ -54,6 +54,64 @@ module_param(debug, int, 0);
 MODULE_PARM_DESC(debug, "set this to 1 (and RTFM) if you want to help "
 		 "the development of this driver");
 
+/*********** Platform Device ***********/
+
+static atomic_t sony_pf_users = ATOMIC_INIT(0);
+static struct platform_driver sony_pf_driver = {
+	.driver = {
+		   .name = "sony-laptop",
+		   .owner = THIS_MODULE,
+		   }
+};
+static struct platform_device *sony_pf_device;
+
+static int sony_pf_add(void)
+{
+	int ret = 0;
+
+	/* don't run again if already initialized */
+	if (atomic_add_return(1, &sony_pf_users) > 1)
+		return 0;
+
+	ret = platform_driver_register(&sony_pf_driver);
+	if (ret)
+		goto out;
+
+	sony_pf_device = platform_device_alloc("sony-laptop", -1);
+	if (!sony_pf_device) {
+		ret = -ENOMEM;
+		goto out_platform_registered;
+	}
+
+	ret = platform_device_add(sony_pf_device);
+	if (ret)
+		goto out_platform_alloced;
+
+	return 0;
+
+      out_platform_alloced:
+	platform_device_put(sony_pf_device);
+	sony_pf_device = NULL;
+      out_platform_registered:
+	platform_driver_unregister(&sony_pf_driver);
+      out:
+	atomic_dec(&sony_pf_users);
+	return ret;
+}
+
+static void sony_pf_remove(void)
+{
+	/* deregister only after the last user has gone */
+	if (!atomic_dec_and_test(&sony_pf_users))
+		return;
+
+	platform_device_del(sony_pf_device);
+	platform_device_put(sony_pf_device);
+	platform_driver_unregister(&sony_pf_driver);
+}
+
+/*********** SNC (SNY5001) Device ***********/
+
 static ssize_t sony_nc_sysfs_show(struct device *, struct device_attribute *,
 			      char *);
 static ssize_t sony_nc_sysfs_store(struct device *, struct device_attribute *,
@@ -279,104 +337,6 @@ static ssize_t sony_nc_sysfs_store(struct device *dev,
 	return count;
 }
 
-/*
- * Platform device
- */
-static struct platform_driver sncpf_driver = {
-	.driver = {
-		   .name = "sony-laptop",
-		   .owner = THIS_MODULE,
-		   }
-};
-static struct platform_device *sncpf_device;
-
-static int sony_nc_pf_add(void)
-{
-	acpi_handle handle;
-	struct sony_nc_value *item;
-	int ret = 0;
-
-	ret = platform_driver_register(&sncpf_driver);
-	if (ret)
-		goto out;
-
-	sncpf_device = platform_device_alloc("sony-laptop", -1);
-	if (!sncpf_device) {
-		ret = -ENOMEM;
-		goto out_platform_registered;
-	}
-
-	ret = platform_device_add(sncpf_device);
-	if (ret)
-		goto out_platform_alloced;
-
-	for (item = sony_nc_values; item->name; ++item) {
-
-		if (!debug && item->debug)
-			continue;
-
-		/* find the available acpiget as described in the DSDT */
-		for (; item->acpiget && *item->acpiget; ++item->acpiget) {
-			if (ACPI_SUCCESS(acpi_get_handle(sony_nc_acpi_handle,
-							 *item->acpiget,
-							 &handle))) {
-				if (debug)
-					printk(LOG_PFX "Found %s getter: %s\n",
-					       item->name, *item->acpiget);
-				item->devattr.attr.mode |= S_IRUGO;
-				break;
-			}
-		}
-
-		/* find the available acpiset as described in the DSDT */
-		for (; item->acpiset && *item->acpiset; ++item->acpiset) {
-			if (ACPI_SUCCESS(acpi_get_handle(sony_nc_acpi_handle,
-							 *item->acpiset,
-							 &handle))) {
-				if (debug)
-					printk(LOG_PFX "Found %s setter: %s\n",
-					       item->name, *item->acpiset);
-				item->devattr.attr.mode |= S_IWUSR;
-				break;
-			}
-		}
-
-		if (item->devattr.attr.mode != 0) {
-			ret =
-			    device_create_file(&sncpf_device->dev,
-					       &item->devattr);
-			if (ret)
-				goto out_sysfs;
-		}
-	}
-
-	return 0;
-
-      out_sysfs:
-	for (item = sony_nc_values; item->name; ++item) {
-		device_remove_file(&sncpf_device->dev, &item->devattr);
-	}
-	platform_device_del(sncpf_device);
-      out_platform_alloced:
-	platform_device_put(sncpf_device);
-      out_platform_registered:
-	platform_driver_unregister(&sncpf_driver);
-      out:
-	return ret;
-}
-
-static void sony_nc_pf_remove(void)
-{
-	struct sony_nc_value *item;
-
-	for (item = sony_nc_values; item->name; ++item) {
-		device_remove_file(&sncpf_device->dev, &item->devattr);
-	}
-
-	platform_device_del(sncpf_device);
-	platform_device_put(sncpf_device);
-	platform_driver_unregister(&sncpf_driver);
-}
 
 /*
  * Backlight device
@@ -455,6 +415,7 @@ static int sony_nc_add(struct acpi_device *device)
 	acpi_status status;
 	int result = 0;
 	acpi_handle handle;
+	struct sony_nc_value *item;
 
 	sony_nc_acpi_device = device;
 
@@ -497,13 +458,59 @@ static int sony_nc_add(struct acpi_device *device)
 
 	}
 
-	if (sony_nc_pf_add())
+	if (sony_pf_add())
 		goto outbacklight;
 
+	/* create sony_pf sysfs attributes related to the SNC device */
+	for (item = sony_nc_values; item->name; ++item) {
+
+		if (!debug && item->debug)
+			continue;
+
+		/* find the available acpiget as described in the DSDT */
+		for (; item->acpiget && *item->acpiget; ++item->acpiget) {
+			if (ACPI_SUCCESS(acpi_get_handle(sony_nc_acpi_handle,
+							 *item->acpiget,
+							 &handle))) {
+				if (debug)
+					printk(LOG_PFX "Found %s getter: %s\n",
+					       item->name, *item->acpiget);
+				item->devattr.attr.mode |= S_IRUGO;
+				break;
+			}
+		}
+
+		/* find the available acpiset as described in the DSDT */
+		for (; item->acpiset && *item->acpiset; ++item->acpiset) {
+			if (ACPI_SUCCESS(acpi_get_handle(sony_nc_acpi_handle,
+							 *item->acpiset,
+							 &handle))) {
+				if (debug)
+					printk(LOG_PFX "Found %s setter: %s\n",
+					       item->name, *item->acpiset);
+				item->devattr.attr.mode |= S_IWUSR;
+				break;
+			}
+		}
+
+		if (item->devattr.attr.mode != 0) {
+			result =
+			    device_create_file(&sony_pf_device->dev,
+					       &item->devattr);
+			if (result)
+				goto out_sysfs;
+		}
+	}
+
 	printk(KERN_INFO SONY_NC_DRIVER_NAME " successfully installed\n");
 
 	return 0;
 
+      out_sysfs:
+	for (item = sony_nc_values; item->name; ++item) {
+		device_remove_file(&sony_pf_device->dev, &item->devattr);
+	}
+	sony_pf_remove();
       outbacklight:
 	if (sony_backlight_device)
 		backlight_device_unregister(sony_backlight_device);
@@ -520,6 +527,7 @@ static int sony_nc_add(struct acpi_device *device)
 static int sony_nc_remove(struct acpi_device *device, int type)
 {
 	acpi_status status;
+	struct sony_nc_value *item;
 
 	if (sony_backlight_device)
 		backlight_device_unregister(sony_backlight_device);
@@ -532,7 +540,11 @@ static int sony_nc_remove(struct acpi_device *device, int type)
 	if (ACPI_FAILURE(status))
 		printk(LOG_PFX "unable to remove notify handler\n");
 
-	sony_nc_pf_remove();
+	for (item = sony_nc_values; item->name; ++item) {
+		device_remove_file(&sony_pf_device->dev, &item->devattr);
+	}
+
+	sony_pf_remove();
 
 	printk(KERN_INFO SONY_NC_DRIVER_NAME " successfully removed\n");