mfd: simple-mfd-i2c: Add support for registering devices via MFD cells

More devices are cropping up requiring only Regmap initialisation and
child registration functionality.  We currently only support that if
all required devices are represented by their own Device Tree nodes
complete with compatible strings.

However, not everyone is happy with adding empty nodes that provide no
additional device information into the Device Tree.

Rather than have a plethora of mostly empty, function-less drivers in
MFD, we'll support those simple cases in here instead via MFD cells.

Cc: Mark Brown <broonie@kernel.org>
Tested-by: Michael Walle <michael@walle.cc>
Reviewed-by: Alistair Francis <alistair@alistair23.me>
Tested-by: Alistair Francis <alistair@alistair23.me>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

1 files changed, 32 insertions, 0 deletions

diff --git a/drivers/mfd/simple-mfd-i2c.h b/drivers/mfd/simple-mfd-i2c.h
new file mode 100644
index 000000000000..7cb2bdd347d9
--- /dev/null
+++ b/drivers/mfd/simple-mfd-i2c.h
@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Simple MFD - I2C
+ *
+ * Author: Lee Jones <lee.jones@linaro.org>
+ *
+ * This driver creates a single register map with the intention for it to be
+ * shared by all sub-devices.  Children can use their parent's device structure
+ * (dev.parent) in order to reference it.
+ *
+ * This driver creates a single register map with the intention for it to be
+ * shared by all sub-devices.  Children can use their parent's device structure
+ * (dev.parent) in order to reference it.
+ *
+ * Once the register map has been successfully initialised, any sub-devices
+ * represented by child nodes in Device Tree or via the MFD cells in the
+ * associated C file will be subsequently registered.
+ */
+
+#ifndef __MFD_SIMPLE_MFD_I2C_H
+#define __MFD_SIMPLE_MFD_I2C_H
+
+#include <linux/mfd/core.h>
+#include <linux/regmap.h>
+
+struct simple_mfd_data {
+	const struct regmap_config *regmap_config;
+	const struct mfd_cell *mfd_cell;
+	size_t mfd_cell_size;
+};
+
+#endif /* __MFD_SIMPLE_MFD_I2C_H */