power: add FAN53555 family support

This adds a driver for the FAN53555 family of regulators and wraps it
in a PMIC implementation.

While these devices support a 'normal' and 'suspend' mode (controlled
via an external pin) to switch between two programmable voltages, this
incarnation of the driver assumes that the device is always operating
in 'normal' mode.

Only setting/reading the programmed voltage is supported at this time
and the following device functionality remains unsupported:
  - switching the selected voltage (via a GPIO)
  - disabling the voltage output via software-control
This matches the functionality of the Linux driver.

Tested on a RK3399-Q7 (with 'option 5' devices): setting voltages from
the U-Boot shell and verifying output voltages on the board.

Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Tested-by: Klaus Goger <klaus.goger@theobroma-systems.com>

3 files changed, 97 insertions, 0 deletions

diff --git a/drivers/power/pmic/Kconfig b/drivers/power/pmic/Kconfig
index cba48e12da..8cf60ebcf3 100644
--- a/drivers/power/pmic/Kconfig
+++ b/drivers/power/pmic/Kconfig
@@ -48,6 +48,20 @@ config PMIC_AS3722
 	  interface and is designs to cover most of the power managementment
 	  required for a tablets or laptop.
 
+config DM_PMIC_FAN53555
+	bool "Enable support for OnSemi FAN53555"
+	depends on DM_PMIC && DM_REGULATOR && DM_I2C
+	select DM_REGULATOR_FAN53555
+	help
+	  This config enables implementation of driver-model PMIC
+	  uclass features for the FAN53555 regulator. The FAN53555 is
+	  a (family of) single-output regulators that supports
+	  transitioning between two different output voltages based on
+	  an voltage selection pin.
+
+	  The driver implements read/write operations for use with the FAN53555
+	  regulator driver and binds the regulator driver to its node.
+
 config DM_PMIC_PFUZE100
 	bool "Enable Driver Model for PMIC PFUZE100"
 	depends on DM_PMIC
diff --git a/drivers/power/pmic/Makefile b/drivers/power/pmic/Makefile
index 29ca442933..637352ab2b 100644
--- a/drivers/power/pmic/Makefile
+++ b/drivers/power/pmic/Makefile
@@ -4,6 +4,7 @@
 # Lukasz Majewski <l.majewski@samsung.com>
 
 obj-$(CONFIG_DM_PMIC) += pmic-uclass.o
+obj-$(CONFIG_DM_PMIC_FAN53555) += fan53555.o
 obj-$(CONFIG_DM_PMIC_MAX77686) += max77686.o
 obj-$(CONFIG_DM_PMIC_MAX8998) += max8998.o
 obj-$(CONFIG_DM_PMIC_MC34708) += mc34708.o
diff --git a/drivers/power/pmic/fan53555.c b/drivers/power/pmic/fan53555.c
new file mode 100644
index 0000000000..1ca59c5f0c
--- /dev/null
+++ b/drivers/power/pmic/fan53555.c
@@ -0,0 +1,82 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * (C) 2018 Theobroma Systems Design und Consulting GmbH
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <dm/device-internal.h>
+#include <dm/lists.h>
+#include <i2c.h>
+#include <power/pmic.h>
+#include <power/regulator.h>
+
+static int pmic_fan53555_reg_count(struct udevice *dev)
+{
+	return 1;
+};
+
+static int pmic_fan53555_read(struct udevice *dev, uint reg,
+			      u8 *buff, int len)
+{
+	if (dm_i2c_read(dev, reg, buff, len)) {
+		pr_err("%s: read error for register: %#x!", dev->name, reg);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int pmic_fan53555_write(struct udevice *dev, uint reg,
+			       const u8 *buff, int len)
+{
+	if (dm_i2c_write(dev, reg, buff, len)) {
+		pr_err("%s: write error for register: %#x!", dev->name, reg);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int pmic_fan53555_bind(struct udevice *dev)
+{
+	/*
+	 * The FAN53555 has only a single regulator and therefore doesn't
+	 * have a subnode.  So we have to rebind a child device (the one
+	 * regulator) here.
+	 */
+
+	const char *regulator_driver_name = "fan53555_regulator";
+	struct udevice *child;
+	struct driver *drv;
+
+	debug("%s\n", __func__);
+
+	drv = lists_driver_lookup_name(regulator_driver_name);
+	if (!drv) {
+		dev_err(dev, "no driver '%s'\n", regulator_driver_name);
+		return -ENOENT;
+	}
+
+	return device_bind_with_driver_data(dev, drv, "SW", 0,
+					    dev_ofnode(dev), &child);
+};
+
+static struct dm_pmic_ops pmic_fan53555_ops = {
+	.reg_count = pmic_fan53555_reg_count,
+	.read = pmic_fan53555_read,
+	.write = pmic_fan53555_write,
+};
+
+static const struct udevice_id pmic_fan53555_match[] = {
+	{ .compatible = "fcs,fan53555" },
+	{ },
+};
+
+U_BOOT_DRIVER(pmic_fan53555) = {
+	.name = "pmic_fan53555",
+	.id = UCLASS_PMIC,
+	.of_match = pmic_fan53555_match,
+	.bind = pmic_fan53555_bind,
+	.ops = &pmic_fan53555_ops,
+};