regulator: bd71837: copy the bd71837 pmic driver from NXP imx u-boot

https://source.codeaurora.org/external/imx/uboot-imx

cherry picked, styled and merged commits:
- MLK-18387 pmic: Add pmic driver for BD71837: e9a3bec2e95a
- MLK-18590 pmic: bd71837: Change to use new fdt API: acdc5c297a96

Signed-off-by: Ye Li <ye.li@nxp.com>
Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/power/pmic/bd71837.c b/drivers/power/pmic/bd71837.c
new file mode 100644
index 0000000..24d9f7f
--- /dev/null
+++ b/drivers/power/pmic/bd71837.c
@@ -0,0 +1,89 @@
+// SPDX-License-Identifier:      GPL-2.0+
+/*
+ * Copyright 2018 NXP
+ */
+
+#include <common.h>
+#include <errno.h>
+#include <dm.h>
+#include <i2c.h>
+#include <power/pmic.h>
+#include <power/regulator.h>
+#include <power/bd71837.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+static const struct pmic_child_info pmic_children_info[] = {
+	/* buck */
+	{ .prefix = "b", .driver = BD71837_REGULATOR_DRIVER},
+	/* ldo */
+	{ .prefix = "l", .driver = BD71837_REGULATOR_DRIVER},
+	{ },
+};
+
+static int bd71837_reg_count(struct udevice *dev)
+{
+	return BD71837_REG_NUM;
+}
+
+static int bd71837_write(struct udevice *dev, uint reg, const uint8_t *buff,
+			 int len)
+{
+	if (dm_i2c_write(dev, reg, buff, len)) {
+		pr_err("write error to device: %p register: %#x!", dev, reg);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int bd71837_read(struct udevice *dev, uint reg, uint8_t *buff, int len)
+{
+	if (dm_i2c_read(dev, reg, buff, len)) {
+		pr_err("read error from device: %p register: %#x!", dev, reg);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int bd71837_bind(struct udevice *dev)
+{
+	int children;
+	ofnode regulators_node;
+
+	regulators_node = dev_read_subnode(dev, "regulators");
+	if (!ofnode_valid(regulators_node)) {
+		debug("%s: %s regulators subnode not found!", __func__,
+		      dev->name);
+		return -ENXIO;
+	}
+
+	debug("%s: '%s' - found regulators subnode\n", __func__, dev->name);
+
+	children = pmic_bind_children(dev, regulators_node, pmic_children_info);
+	if (!children)
+		debug("%s: %s - no child found\n", __func__, dev->name);
+
+	/* Always return success for this device */
+	return 0;
+}
+
+static struct dm_pmic_ops bd71837_ops = {
+	.reg_count = bd71837_reg_count,
+	.read = bd71837_read,
+	.write = bd71837_write,
+};
+
+static const struct udevice_id bd71837_ids[] = {
+	{ .compatible = "rohm,bd71837", .data = 0x4b, },
+	{ }
+};
+
+U_BOOT_DRIVER(pmic_bd71837) = {
+	.name = "bd71837 pmic",
+	.id = UCLASS_PMIC,
+	.of_match = bd71837_ids,
+	.bind = bd71837_bind,
+	.ops = &bd71837_ops,
+};