Add auxiliary bus support

Add support for the Auxiliary Bus, auxiliary_device and auxiliary_driver.
It enables drivers to create an auxiliary_device and bind an
auxiliary_driver to it.

The bus supports probe/remove shutdown and suspend/resume callbacks.
Each auxiliary_device has a unique string based id; driver binds to
an auxiliary_device based on this id through the bus.

Co-developed-by: Kiran Patil <kiran.patil@intel.com>
Co-developed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Co-developed-by: Fred Oh <fred.oh@linux.intel.com>
Co-developed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Kiran Patil <kiran.patil@intel.com>
Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Signed-off-by: Fred Oh <fred.oh@linux.intel.com>
Signed-off-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Dave Ertman <david.m.ertman@intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Shiraz Saleem <shiraz.saleem@intel.com>
Reviewed-by: Parav Pandit <parav@mellanox.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Reviewed-by: Martin Habets <mhabets@solarflare.com>
Link: https://lore.kernel.org/r/20201113161859.1775473-2-david.m.ertman@intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Link: https://lore.kernel.org/r/160695681289.505290.8978295443574440604.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 78 insertions, 0 deletions

diff --git a/include/linux/auxiliary_bus.h b/include/linux/auxiliary_bus.h
new file mode 100644
index 000000000000..282fbf7bf9af
--- /dev/null
+++ b/include/linux/auxiliary_bus.h
@@ -0,0 +1,78 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2019-2020 Intel Corporation
+ *
+ * Please see Documentation/driver-api/auxiliary_bus.rst for more information.
+ */
+
+#ifndef _AUXILIARY_BUS_H_
+#define _AUXILIARY_BUS_H_
+
+#include <linux/device.h>
+#include <linux/mod_devicetable.h>
+#include <linux/slab.h>
+
+struct auxiliary_device {
+	struct device dev;
+	const char *name;
+	u32 id;
+};
+
+struct auxiliary_driver {
+	int (*probe)(struct auxiliary_device *auxdev, const struct auxiliary_device_id *id);
+	int (*remove)(struct auxiliary_device *auxdev);
+	void (*shutdown)(struct auxiliary_device *auxdev);
+	int (*suspend)(struct auxiliary_device *auxdev, pm_message_t state);
+	int (*resume)(struct auxiliary_device *auxdev);
+	const char *name;
+	struct device_driver driver;
+	const struct auxiliary_device_id *id_table;
+};
+
+static inline struct auxiliary_device *to_auxiliary_dev(struct device *dev)
+{
+	return container_of(dev, struct auxiliary_device, dev);
+}
+
+static inline struct auxiliary_driver *to_auxiliary_drv(struct device_driver *drv)
+{
+	return container_of(drv, struct auxiliary_driver, driver);
+}
+
+int auxiliary_device_init(struct auxiliary_device *auxdev);
+int __auxiliary_device_add(struct auxiliary_device *auxdev, const char *modname);
+#define auxiliary_device_add(auxdev) __auxiliary_device_add(auxdev, KBUILD_MODNAME)
+
+static inline void auxiliary_device_uninit(struct auxiliary_device *auxdev)
+{
+	put_device(&auxdev->dev);
+}
+
+static inline void auxiliary_device_delete(struct auxiliary_device *auxdev)
+{
+	device_del(&auxdev->dev);
+}
+
+int __auxiliary_driver_register(struct auxiliary_driver *auxdrv, struct module *owner,
+				const char *modname);
+#define auxiliary_driver_register(auxdrv) \
+	__auxiliary_driver_register(auxdrv, THIS_MODULE, KBUILD_MODNAME)
+
+void auxiliary_driver_unregister(struct auxiliary_driver *auxdrv);
+
+/**
+ * module_auxiliary_driver() - Helper macro for registering an auxiliary driver
+ * @__auxiliary_driver: auxiliary driver struct
+ *
+ * Helper macro for auxiliary drivers which do not do anything special in
+ * module init/exit. This eliminates a lot of boilerplate. Each module may only
+ * use this macro once, and calling it replaces module_init() and module_exit()
+ */
+#define module_auxiliary_driver(__auxiliary_driver) \
+	module_driver(__auxiliary_driver, auxiliary_driver_register, auxiliary_driver_unregister)
+
+struct auxiliary_device *
+auxiliary_find_device(struct device *start, const void *data,
+		      int (*match)(struct device *dev, const void *data));
+
+#endif /* _AUXILIARY_BUS_H_ */