driver-core: platform: Provide helpers for multi-driver modules

Some modules register several sub-drivers. Provide a helper that makes
it easy to register and unregister a list of sub-drivers, as well as
unwind properly on error.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 61 insertions, 0 deletions

diff --git a/drivers/base/platform.c b/drivers/base/platform.c
index 07cec9ba5e70..1dd6d3bf1098 100644
--- a/drivers/base/platform.c
+++ b/drivers/base/platform.c
@@ -710,6 +710,67 @@ err_out:
 }
 EXPORT_SYMBOL_GPL(__platform_create_bundle);
 
+/**
+ * __platform_register_drivers - register an array of platform drivers
+ * @drivers: an array of drivers to register
+ * @count: the number of drivers to register
+ * @owner: module owning the drivers
+ *
+ * Registers platform drivers specified by an array. On failure to register a
+ * driver, all previously registered drivers will be unregistered. Callers of
+ * this API should use platform_unregister_drivers() to unregister drivers in
+ * the reverse order.
+ *
+ * Returns: 0 on success or a negative error code on failure.
+ */
+int __platform_register_drivers(struct platform_driver * const *drivers,
+                                unsigned int count, struct module *owner)
+{
+        unsigned int i;
+        int err;
+
+        for (i = 0; i < count; i++) {
+                pr_debug("registering platform driver %ps\n", drivers[i]);
+
+                err = __platform_driver_register(drivers[i], owner);
+                if (err < 0) {
+                        pr_err("failed to register platform driver %ps: %d\n",
+                               drivers[i], err);
+                        goto error;
+                }
+        }
+
+        return 0;
+
+error:
+        while (i--) {
+                pr_debug("unregistering platform driver %ps\n", drivers[i]);
+                platform_driver_unregister(drivers[i]);
+        }
+
+        return err;
+}
+EXPORT_SYMBOL_GPL(__platform_register_drivers);
+
+/**
+ * platform_unregister_drivers - unregister an array of platform drivers
+ * @drivers: an array of drivers to unregister
+ * @count: the number of drivers to unregister
+ *
+ * Unegisters platform drivers specified by an array. This is typically used
+ * to complement an earlier call to platform_register_drivers(). Drivers are
+ * unregistered in the reverse order in which they were registered.
+ */
+void platform_unregister_drivers(struct platform_driver * const *drivers,
+                                 unsigned int count)
+{
+        while (count--) {
+                pr_debug("unregistering platform driver %ps\n", drivers[count]);
+                platform_driver_unregister(drivers[count]);
+        }
+}
+EXPORT_SYMBOL_GPL(platform_unregister_drivers);
+
 /* modalias support enables more hands-off userspace setup:
  * (a) environment variable lets new-style hotplug events work once system is
  *     fully running:  "modprobe $MODALIAS"