dm: pmic: add max77686 pmic driver

This is the implementation of driver model PMIC driver.
The max77686 PMIC driver implements read/write operations and driver
bind method - to bind its childs.

This driver will try to bind the regulator devices by using it's child
info array with regulator prefixes and driver names. This should succeed
when compatible regulator driver is compiled. If no regulator driver found,
then the pmic can still provide read/write operations, and can be used with
PMIC function calls.

Signed-off-by: Przemyslaw Marczak <p.marczak@samsung.com>
Acked-by: Simon Glass <sjg@chromium.org>

doc/device-tree-bindings/pmic/max77686.txt

+MAXIM, MAX77686 pmic
+
+This device uses two drivers:
+- drivers/power/pmic/max77686.c (for parent device)
+- drivers/power/regulator/max77686.c (for child regulators)
+
+This file describes the binding info for the PMIC driver.
+
+To bind the regulators, please read the additional binding info:
+- doc/device-tree-bindings/regulator/max77686.txt
+
+Required properties:
+- compatible: "maxim,max77686"
+- reg = 0x9
+
+With those two properties, the pmic device can be used for read/write only.
+To bind each regulator, the optional regulators subnode should exists.
+
+Optional subnode:
+- voltage-regulators: subnode list of each device's regulator
+  (see max77686.txt - regulator binding info)
+
+Example:
+
+max77686@09 {
+	compatible = "maxim,max77686";
+	reg = <0x09>;
+
+	voltage-regulators {
+		ldo1 {
+			...
+		};
+		...
+	};
+};

drivers/power/pmic/Kconfig

@@ -9,3 +9,10 @@ config DM_PMIC
 	for read/write. For detailed description, please refer to the files:
 	- 'drivers/power/pmic/pmic-uclass.c'
 	- 'include/power/pmic.h'
+
+config DM_PMIC_MAX77686
+	bool "Enable Driver Model for PMIC MAX77686"
+	depends on DM_PMIC
+	---help---
+	This config enables implementation of driver-model pmic uclass features
+	for PMIC MAX77686. The driver implements read/write operations.
\ No newline at end of file

drivers/power/pmic/Makefile

@@ -11,6 +11,7 @@ obj-$(CONFIG_POWER_MAX8998) += pmic_max8998.o
 obj-$(CONFIG_POWER_MAX8997) += pmic_max8997.o
 obj-$(CONFIG_POWER_MUIC_MAX8997) += muic_max8997.o
 obj-$(CONFIG_POWER_MAX77686) += pmic_max77686.o
+obj-$(CONFIG_DM_PMIC_MAX77686) += max77686.o
 obj-$(CONFIG_POWER_PFUZE100) += pmic_pfuze100.o
 obj-$(CONFIG_POWER_TPS65090_I2C) += pmic_tps65090.o
 obj-$(CONFIG_POWER_TPS65090_EC) += pmic_tps65090_ec.o

drivers/power/pmic/max77686.c

+/*
+ *  Copyright (C) 2014-2015 Samsung Electronics
+ *  Przemyslaw Marczak  <p.marczak@samsung.com>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <fdtdec.h>
+#include <errno.h>
+#include <dm.h>
+#include <i2c.h>
+#include <power/pmic.h>
+#include <power/regulator.h>
+#include <power/max77686_pmic.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+static const struct pmic_child_info pmic_childs_info[] = {
+	{ .prefix = "ldo", .driver = MAX77686_LDO_DRIVER },
+	{ .prefix = "buck", .driver = MAX77686_BUCK_DRIVER },
+	{ },
+};
+
+static int max77686_write(struct udevice *dev, uint reg, const uint8_t *buff,
+			  int len)
+{
+	if (dm_i2c_write(dev, reg, buff, len)) {
+		error("write error to device: %p register: %#x!", dev, reg);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int max77686_read(struct udevice *dev, uint reg, uint8_t *buff, int len)
+{
+	if (dm_i2c_read(dev, reg, buff, len)) {
+		error("read error from device: %p register: %#x!", dev, reg);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int max77686_bind(struct udevice *dev)
+{
+	int regulators_node;
+	const void *blob = gd->fdt_blob;
+	int childs;
+
+	regulators_node = fdt_subnode_offset(blob, dev->of_offset,
+					     "voltage-regulators");
+	if (regulators_node <= 0) {
+		debug("%s: %s regulators subnode not found!", __func__,
+							     dev->name);
+		return -ENXIO;
+	}
+
+	debug("%s: '%s' - found regulators subnode\n", __func__, dev->name);
+
+	childs = pmic_bind_childs(dev, regulators_node, pmic_childs_info);
+	if (!childs)
+		debug("%s: %s - no child found\n", __func__, dev->name);
+
+	/* Always return success for this device */
+	return 0;
+}
+
+static struct dm_pmic_ops max77686_ops = {
+	.reg_count = MAX77686_NUM_OF_REGS,
+	.read = max77686_read,
+	.write = max77686_write,
+};
+
+static const struct udevice_id max77686_ids[] = {
+	{ .compatible = "maxim,max77686" },
+	{ }
+};
+
+U_BOOT_DRIVER(pmic_max77686) = {
+	.name = "max77686 pmic",
+	.id = UCLASS_PMIC,
+	.of_match = max77686_ids,
+	.bind = max77686_bind,
+	.ops = &max77686_ops,
+};

drivers/power/pmic/pmic_max77686.c

@@ -295,7 +295,7 @@ int pmic_init(unsigned char bus)
 
 	p->name = name;
 	p->interface = PMIC_I2C;
-	p->number_of_regs = PMIC_NUM_OF_REGS;
+	p->number_of_regs = MAX77686_NUM_OF_REGS;
 	p->hw.i2c.tx_num = 1;
 
 	puts("Board PMIC init\n");

include/power/max77686_pmic.h

@@ -122,11 +122,17 @@ enum {
 	MAX77686_REG_PMIC_BBAT		= 0x7e,
 	MAX77686_REG_PMIC_32KHZ,
 
-	PMIC_NUM_OF_REGS,
+	MAX77686_NUM_OF_REGS,
 };
 
 /* I2C device address for pmic max77686 */
-#define MAX77686_I2C_ADDR (0x12 >> 1)
+#define MAX77686_I2C_ADDR	(0x12 >> 1)
+#define MAX77686_LDO_NUM	26
+#define MAX77686_BUCK_NUM	9
+
+/* Drivers name */
+#define MAX77686_LDO_DRIVER	"max77686_ldo"
+#define MAX77686_BUCK_DRIVER	"max77686_buck"
 
 enum {
 	REG_DISABLE = 0,