mfd: axp20x: Add support for RSB based AXP223 PMIC

The AXP223 is a new PMIC commonly paired with Allwinner A23/A33 SoCs.
It is functionally identical to AXP221; only the regulator default
voltage/status and the external host interface are different.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
diff --git a/drivers/mfd/axp20x-rsb.c b/drivers/mfd/axp20x-rsb.c
new file mode 100644
index 0000000..28c2024
--- /dev/null
+++ b/drivers/mfd/axp20x-rsb.c
@@ -0,0 +1,80 @@
+/*
+ * RSB driver for the X-Powers' Power Management ICs
+ *
+ * AXP20x typically comprises an adaptive USB-Compatible PWM charger, BUCK DC-DC
+ * converters, LDOs, multiple 12-bit ADCs of voltage, current and temperature
+ * as well as configurable GPIOs.
+ *
+ * This driver supports the RSB variants.
+ *
+ * Copyright (C) 2015 Chen-Yu Tsai
+ *
+ * Author: Chen-Yu Tsai <wens@csie.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/acpi.h>
+#include <linux/err.h>
+#include <linux/mfd/axp20x.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+#include <linux/sunxi-rsb.h>
+
+static int axp20x_rsb_probe(struct sunxi_rsb_device *rdev)
+{
+	struct axp20x_dev *axp20x;
+	int ret;
+
+	axp20x = devm_kzalloc(&rdev->dev, sizeof(*axp20x), GFP_KERNEL);
+	if (!axp20x)
+		return -ENOMEM;
+
+	axp20x->dev = &rdev->dev;
+	axp20x->irq = rdev->irq;
+	dev_set_drvdata(&rdev->dev, axp20x);
+
+	ret = axp20x_match_device(axp20x);
+	if (ret)
+		return ret;
+
+	axp20x->regmap = devm_regmap_init_sunxi_rsb(rdev, axp20x->regmap_cfg);
+	if (IS_ERR(axp20x->regmap)) {
+		ret = PTR_ERR(axp20x->regmap);
+		dev_err(&rdev->dev, "regmap init failed: %d\n", ret);
+		return ret;
+	}
+
+	return axp20x_device_probe(axp20x);
+}
+
+static int axp20x_rsb_remove(struct sunxi_rsb_device *rdev)
+{
+	struct axp20x_dev *axp20x = sunxi_rsb_device_get_drvdata(rdev);
+
+	return axp20x_device_remove(axp20x);
+}
+
+static const struct of_device_id axp20x_rsb_of_match[] = {
+	{ .compatible = "x-powers,axp223", .data = (void *)AXP223_ID },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, axp20x_rsb_of_match);
+
+static struct sunxi_rsb_driver axp20x_rsb_driver = {
+	.driver = {
+		.name	= "axp20x-rsb",
+		.of_match_table	= of_match_ptr(axp20x_rsb_of_match),
+	},
+	.probe	= axp20x_rsb_probe,
+	.remove	= axp20x_rsb_remove,
+};
+module_sunxi_rsb_driver(axp20x_rsb_driver);
+
+MODULE_DESCRIPTION("PMIC MFD sunXi RSB driver for AXP20X");
+MODULE_AUTHOR("Chen-Yu Tsai <wens@csie.org>");
+MODULE_LICENSE("GPL v2");