[PATCH v4 1/6] mfd: implement mfd_add_devices

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

This makes it easier to port Linux drivers like PMICs, where a device
tree probed MFD node exists and the driver matching against it then
registers a number of MFD cell devices, which don't have their own
DT compatibles.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
v3 -> v4:
  - no change
v2 -> v3:
  - no change
v1 -> v2:
  - no change
v0 (before folding into series) -> v1:
  - call device_add_data before platform_device_register, which
    may immediately probe (Sascha)
---
 drivers/base/resource.c  |  2 +-
 drivers/mfd/Makefile     |  2 ++
 drivers/mfd/core.c       | 25 +++++++++++++++++++++++++
 include/driver.h         |  2 +-
 include/linux/mfd/core.h | 23 +++++++++++++++++++++++
 5 files changed, 52 insertions(+), 2 deletions(-)
 create mode 100644 drivers/mfd/core.c
 create mode 100644 include/linux/mfd/core.h

diff --git a/drivers/base/resource.c b/drivers/base/resource.c
index d0d39620772e..0134456ffac2 100644
--- a/drivers/base/resource.c
+++ b/drivers/base/resource.c
@@ -20,7 +20,7 @@ struct device_d *device_alloc(const char *devname, int id)
 	return dev;
 }
 
-int device_add_data(struct device_d *dev, void *data, size_t size)
+int device_add_data(struct device_d *dev, const void *data, size_t size)
 {
 	free(dev->platform_data);
 
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index 50f54cfcf21c..2b988bdc9a3d 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -1,4 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0-only
+obj-y				+= core.o
+
 obj-$(CONFIG_MFD_ACT8846)	+= act8846.o
 obj-$(CONFIG_MFD_DA9053)	+= da9053.o
 obj-$(CONFIG_MFD_DA9063)	+= da9063.o
diff --git a/drivers/mfd/core.c b/drivers/mfd/core.c
new file mode 100644
index 000000000000..495427ae9c87
--- /dev/null
+++ b/drivers/mfd/core.c
@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <linux/mfd/core.h>
+#include <driver.h>
+
+int mfd_add_devices(struct device_d *parent, const struct mfd_cell *cells, int n_devs)
+{
+	struct device_d *dev;
+	int ret, i;
+
+	for (i = 0; i < n_devs; i++) {
+		dev = device_alloc(cells[i].name, DEVICE_ID_DYNAMIC);
+		dev->parent = parent;
+
+		ret = device_add_data(dev, &cells[i], sizeof(cells[i]));
+		if (ret)
+			return ret;
+
+		ret = platform_device_register(dev);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
diff --git a/include/driver.h b/include/driver.h
index a89ce7af9ddd..67ffbba6be80 100644
--- a/include/driver.h
+++ b/include/driver.h
@@ -243,7 +243,7 @@ int device_add_resources(struct device_d *dev, const struct resource *res, int n
 int device_add_resource(struct device_d *dev, const char *resname,
 		resource_size_t start, resource_size_t size, unsigned int flags);
 
-int device_add_data(struct device_d *dev, void *data, size_t size);
+int device_add_data(struct device_d *dev, const void *data, size_t size);
 
 /*
  * register a generic device
diff --git a/include/linux/mfd/core.h b/include/linux/mfd/core.h
new file mode 100644
index 000000000000..2b3b51c69e5f
--- /dev/null
+++ b/include/linux/mfd/core.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2006 Ian Molton
+ * Copyright (c) 2007 Dmitry Baryshkov
+ */
+
+#ifndef MFD_CORE_H
+#define MFD_CORE_H
+
+struct device_d;
+
+/*
+ * This struct describes the MFD part ("cell").
+ * After registration the copy of this structure will become the platform data
+ * of the resulting device_d
+ */
+struct mfd_cell {
+	const char		*name;
+};
+
+int mfd_add_devices(struct device_d *parent, const struct mfd_cell *cells, int n_devs);
+
+#endif
-- 
2.30.2